In studies that compare several diagnostic or treatment groups, subjects may not only be measured on a certain set of feature variables, but also matched on a number of demographic characteristics and measured on additional covariates. Linear discriminant analysis is sometimes used to identify which feature variables best discriminate among groups, while accounting for the dependencies among the feature variables.In this paper, Drs. Asafu-Adjei and Sampson (from Pitt's Department of Statistics) and TNP investigators, Drs. Sweet and Lewis, present a new approach to linear discriminant analysis for multivariate normal data that accounts for the subject matching used in a particular study design, as well as covariates not used in the matching. The motivation for this research came from analyses of human post-mortem brain tissue studies conducted in the Conte Center for the Neuroscience of Mental Disorders (CCNMD).
Applications were given for post-mortem tissue data with the aim of comparing neurobiological characteristics of subjects with schizophrenia to those of normal controls. In addition, the performance of the approach was investigated using a simulation study. In a typical study, schizophrenia subjects and normal controls are paired on age at death, gender, and post-mortem interval (PMI). Auxiliary data such as brain tissue storage time and brain pH are also collected for each subject. Pairs are processed at the same time in a balanced fashion to avoid possible confounding of biomarker measurements by varying reagent strengths, time, and processing personnel.
The proposed methodology produced more accurate classification results compared with both the traditional approaches, where the improvement in the approach became more pronounced as increasing numbers of pairs and increasing differences between the effects for groups were considered.
Asafu-Adjei JK, Sampson AR, Sweet RA, Lewis DA. Adjusting for Matching and Covariates in Linear Discriminant Analysis. Biostatistics, in press.
Markers of GABA neurotransmission are altered in multiple regions of the neocortex in individuals with schizophrenia. Lower levels of glutamic acid decarboxylase 67 (GAD67) mRNA and protein, which is responsible for most cortical GABA synthesis, are accompanied by lower levels of GABA membrane transporter 1 (GAT1) mRNA. These alterations are thought to be most prominent in the parvalbumin (PV)-containing subclass of interneurons, which also contain lower levels of PV mRNA. Since GAT1 and PV each reduce the availability of GABA at postsynaptic receptors, lower levels of GAT1 and PV mRNAs have been hypothesized to represent compensatory responses to an upstream reduction in cortical GABA synthesis in schizophrenia. However, such cause-and-effect hypotheses cannot be directly tested in a human illness. Consequently, we used two mouse models with reduced GAD67 expression specifically in PV neurons (PVGAD67+/-) or in all interneurons (GABAGAD67+/-) and quantified GAD67, GAT1 and PV mRNA levels using methods identical to those employed in studies of schizophrenia. Cortical levels of PV or GAT1 mRNAs were not altered in PVGAD67+/- mice during postnatal development or in adulthood (Figure). Furthermore, cellular analyses confirmed the predicted reduction in GAD67 mRNA, but failed to show a deficit in PV mRNA in these animals. Levels of PV and GAT1 mRNAs were also unaltered in GABAGAD67+/- mice. Thus, mouse lines with cortical reductions in GAD67 mRNA that match or exceed those present in schizophrenia, and that differ in the developmental timing and cell type-specificity of the GAD67 deficit, failed to provide proof-of-concept evidence that lower PV and GAT1 expression in schizophrenia are a consequence of lower GAD67 expression. Together, these findings suggest that the correlated decrements in cortical GAD67, PV and GAT1 mRNAs in schizophrenia may be a common consequence of some other upstream factor. Curley AA, Eggan SM, Lazarus MS, Huang ZJ, Volk DW, Lewis DA: Role of glutamic acid decarboxylase 67 in regulating parvalbumin and GABA membrane transporter 1 expression: Implications for schizophrenia. Neurobiology of Disease, in press.
The cognitive deficits of schizophrenia appear to be associated with altered cortical GABA neurotransmission in the subsets of inhibitory neurons that express either parvalbumin (PV) or somatostatin (SST). Identification of molecular mechanisms that operate selectively in these neurons is essential for developing targeted therapeutic strategies that do not influence other cell types. Consequently, we sought to identify, in the human cortex, gene products that are expressed selectively by PV and/or SST neurons, and that might contribute to their distinctive functional properties. Based on previously reported expression patterns in the cortex of mice and humans, we selected four genes: KCNS3, LHX6, KCNAB1, and PPP1R2, encoding K+ channel Kv9.3 modulatory α-subunit, LIM homeobox protein 6, K+ channel Kvβ1 subunit, and protein phosphatase 1 regulatory subunit 2, respectively, and examined their colocalization with PV or SST mRNAs in the human prefrontal cortex using dual-label in situ hybridization with 35Sand digoxigenin-labeled antisense riboprobes. KCNS3 mRNA was detected in almost all PV neurons, but not in SST neurons, and PV mRNA was detected in >90% of KCNS3 mRNA-expressing neurons (see figure). LHX6 mRNA was detected in almost all PV and >90% of SST neurons, while among all LHX6 mRNA-expressing neurons 50% expressed PV mRNA and >44% expressed SST mRNA. KCNAB1 and PPP1R2 mRNAs were detected in much larger populations of cortical neurons than PV or SST neurons. These findings indicate that KCNS3 is a selective marker of PV neurons, whereas LHX6 is expressed by both PV and SST neurons. KCNS3 and LHX6 might be useful for characterizing cell-type specific molecular alterations of cortical GABA neurotransmission and for the development of novel treatments targeting PV and/or SST neurons in schizophrenia.
Georgiev D, González-Burgos G, Kikuchi M, Minabe Y, Lewis D and Hashimoto T: Selective Expression of KCNS3 Potassium Channel a-Subunit in Parvalbumin-Containing GABA Neurons in the Human Prefrontal Cortex. PLoS ONE 7:e43904, 2012.
Schizophrenia is associated with perceptual and physiological auditory processing impairments which may result from primary auditory cortex excitatory and inhibitory circuit pathology. High-frequency oscillations are important for auditory function, and are often reported to be disrupted in schizophrenia. These oscillations may in part depend on up-regulation of GABA synthesis by glutamate decarboxylase 65 (GAD65) in response to high interneuron firing rates. It is not known whether levels of GAD65 protein, or GAD65-expressing boutons, are altered in schizophrenia. Two cohorts of subjects with schizophrenia and matched controls, comprising 27 pairs of subjects, were studied and relative fluorescence intensity, density, volume, and number of GAD65 immunoreactive boutons in primary auditory cortex were measured using quantitative confocal microscopy and stereologic sampling methods. Bouton fluorescence intensities were used to compare the relative expression of GAD65 protein within boutons between diagnostic groups. Additionally, we assessed the correlation between previously-measured dendritic spine densities and GAD65-immunoreactive bouton fluorescence intensities. GAD65-immunoreactive bouton fluorescence intensity was reduced by 40% in subjects with schizophrenia (see figure), was correlated with previously-measured reduced spine density, and the reduction was greater in subjects who were not living independently at time of death. In contrast, GAD65- immunoreactive bouton density and number were not altered in deep layer 3 of primary auditory cortex of subjects with schizophrenia. Decreased expression of GAD65 protein within inhibitory boutons could contribute to auditory impairments in schizophrenia. The correlated reductions in dendritic spines and GAD65 protein suggest a relationship between inhibitory and excitatory synapse pathology in primary auditory cortex.
Moyer CE, Delevich KM, Fish KN, Asafu-Adje JK, Sampson AR, Dorph-Petersen KA, Lewis DA, Sweet, RA: Reduced glutamate decarboxylase 65 protein within primary auditory cortex inhibitory boutons in schizophrenia. Biol Psychiatry¸ in press.
29th Annual Schizophrenia Conference
Friday, November 30, 2012
Sheraton Station Square Hotel
Pittsburgh, PA
Course Director:
K.N. Roy Chengappa, MD
The Pittsburgh Schizophrenia Conference is an annual meeting at which the advances in schizophrenia research are reviewed by leading experts in the field. This year's meeting will cover a range of topics, including wellness and the role of antioxidants and Omega-3 Fatty Acids in the biology and treatment of schizophrenia. Presentations by the faculty awarded the 2012 Pittsburgh Schizophrenia Conference Awards and the Gerard Hogarty Research Excellence Prize will also take place during the meeting. There will also be a panel addressing issues related to physical wellness and quality of life in persons with serious mental illnesses.
Who Should Attend
The conference is designed to disseminate the latest research findings to a wide audience: psychiatrists and other mental health clinicians, including nurses, social workers, psychologists, service coordinators, researchers, patients and their relatives, mental health policy administrators and others who intend to keep current regarding etiologic and treatment research in schizophrenia.
Objectives
At the conclusion of the program, participants should be able to:
- Describe the potential for adjunctive use of Omega-3 Fatty Acids or antioxidants in the treatment of persons with schizophrenia.
- Access wellness resources and apply wellness strategies designed to improve physical health and quality of life in people living with a diagnosis of schizophrenia or related disorders.
- Identify when it may be beneficial to employ both pharmacologic and behavioral treatments to improve cognition in persons living with a diagnosis of schizophrenia or related disorders.
UPMC Health System Western Psychiatric Institute & Clinic;
Services and Research for Recovery in Serious Mental Illness;
Mental Health Conference Planning;
University of Pittsburgh School of Medicine;
Center for Continuing Education in the Health Sciences
Please click here for more information or contact Nancy Mundy at mundynl@upmc.edu
The ten week summer program for the CCNMD Undergraduate Research Fellowship ended on Friday, July 27 2012. During the summer, the fellows spent many hours in their mentors' labs collecting and analyzing data for a research project. In addition to their research experience, the students participated in several training activities, including weekly seminars, journal club discussions, clinical shadowing opportunities, and teaching sessions on research strategies, ethics and career development. At the end of the summer, each fellow presented their study and responded to questions from an audience of faculty, post-doctoral fellows, graduate students, and peers. Audience members agreed that the overall quality of the presentations was extremely high.Congratulations to all the fellows!
More information on the Fellowship program can be found here.
In schizophrenia, alterations within the prefrontal cortical GABA system appear to be most prominent in neurons that contain parvalbumin or somatostatin but not calretinin. The transcription factors Lhx6 and Sox6 play critical roles in the specification, migration, and maturation of parvalbumin and somatostatin, but not calretinin, neurons and continue to be strongly expressed in this cell type¬specific manner in the prefrontal cortex of adult humans. Therefore, we investigated whether Lhx6 and/or Sox6 mRNA levels are deficient in schizophrenia, which may contribute to cell type¬specific disturbances in cortical parvalbumin and somatostatin neurons. We used quantitative PCR and in situ hybridization with film and grain counting analyses to quantify mRNA levels in prefrontal cortex area 9 of 42 schizophrenia and 42 healthy comparison subjects and in antipsychotic¬exposed monkeys. In schizophrenia subjects, we found lower mRNA levels for Lhx6, parvalbumin, somatostatin, and GAD67 (the principal enzyme in GABA synthesis), but not Sox6 or calretinin. Cluster analysis revealed that a subset of schizophrenia subjects consistently showed the most severe deficits in the affected transcripts. This subset of schizophrenia subjects had lower average mRNA levels for Lhx6, GAD67, parvalbumin, and somatostatin, but not calretinin or Sox6, relative to all other schizophrenia subjects and to healthy comparison subjects (see figure). Grain counting analyses revealed that some neurons that normally express Lhx6 were not detectable in schizophrenia. Finally, lower Lhx6 mRNA levels were not attributable to psychotropic medications or illness chronicity. These data suggest that in a subset of schizophrenia subjects, Lhx6 deficits may contribute to a failure of some cortical parvalbumin and somatostatin neurons to successfully migrate or develop a detectable GABAergic phenotype.
Volk DW, Matsubara T, Li S, Sengupta EJ, Georgiev D, Minabe Y, Sampson A, Hashimoto T, Lewis DA: Deficits in transcriptional regulators of cortical parvalbumin neurons in schizophrenia. Am J Psychiatry, in press.
Schizophrenia is a neurodevelopmental disorder whose clinical features include impairments in perception, cognition and motivation. These impairments reflect alterations in neuronal circuitry within and across multiple brain regions that are due, at least in part, to deficits in dendritic spines, the site of most excitatory synaptic connections. Dendritic spine alterations have been identified in multiple brain regions in schizophrenia, but are best characterized in layer 3 of the neocortex, where pyramidal cell spine density is lower. These spine deficits appear to arise during development, and thus are likely the result of disturbances in the molecular mechanisms that underlie spine formation, pruning, and/or maintenance. Whether the spine deficits reflect a cell-autonomous process or are secondary to alterations in cortical afferents (see figure) remains to be determined. Distinguishing between the alternatives may provide insight into novel therapeutic targets for preventing or repairing the alterations in neural circuitry that mediate the debilitating symptoms of schizophrenia.
Glausier JR and Lewis DA: Dendritic spine pathology in schizophrenia. Neuroscience, in press.
Deficits in cognitive control, a core disturbance of schizophrenia, appear to emerge from impaired prefrontal gamma oscillations. Cortical gamma oscillations require strong inhibitory inputs to pyramidal neurons from the parvalbumin basket cell (PVBC) class of GABAergic neurons. Recent findings indicate that schizophrenia is associated with multiple pre- and post-synaptic abnormalities in PVBCs, each of which weakens their inhibitory control of pyramidal cells. These findings suggest a new model of cortical dysfunction in schizophrenia in which PVBC inhibition is decreased to compensate for an upstream deficit in pyramidal cell excitation. The figure illustrates connectivity between pyramidal (P) neurons and PVBC and chandelier (PVChC) cells in DLPFC layer 3. Reciprocal connections formed by the local axon collaterals of pyramidal neurons provide recurrent excitation, whereas the excitatory inputs from pyramidal neurons to PV basket cells furnish feedback inhibition. These connections are critical for generating gamma band oscillations, and the strengths of these connections are adjusted to maintain normal E/I balance in the healthy brain (top). In schizophrenia, lower spine density in layer 3 pyramidal neurons is hypothesized to result in lower network excitation, evoking a compensatory reduction in feedback inhibition of pyramidal neurons from PVBCs (less presynaptic GAD67; fewer postsynaptic GABAA a1 receptors) and increased depolarization of pyramidal neurons by PVChs (less presynaptic GABA membrane transporter 1; more postsynaptic GABAA a2 receptors). This compensation is thought to re-balance cortical excitation and inhibition, but at a level of each that is insufficient to generate the gamma oscillation power required for high levels of cognitive control.
Lewis DA, Curley AA, Glausier JR, Volk DW: Cortical parvalbumin interneurons and cognitive dysfunction in schizophrenia. Trends Neurosci 35:57-67, 2012.
Jill Glausier, Ph.D., Receives SOBP Travel Award
The Society of Biological Psychiatry (SOBP) annually selects a group of talented young scientists in the field of biological psychiatry to receive Young Investigator Domestic Travel Awards. Dr. Jill Glausier, a post-doctoral scholar in the lab of Dr. David Lewis, was one of the six recipients of the domestic travel award this year. The highly competitive merit-based award is given to promising young investigators within North America who would benefit from attending the annual SOBP Meeting, and covers the costs of travel to conference.
CONGRATULATIONS TO JILL!
May 18, 2012
Sheraton Station Square Hotel
Pittsburgh, PA
For more information, please click here and look for the STEP symposium link.
| New Recipients: Kokomma Ekong Mahjub Hammond Madeline Leo Sowmya Sanapala Ashley Smith |
Continuing Fellows: Franklyn Boothe Tyler Hein Joseph Kern Michael Kitchens Valerie Michael |
Cameron Olezene Wasiq Sheikh Ben Siegel Ryan Stolakis Thomas Wozny |
More information on the Fellowship program can be found here.
In this in-depth group interview hosted by Emmy award-winning interviewer and broadcast journalist, Charlie Rose, some of the major advances in understanding schizophrenia are discussed. The episode was broadcast on Friday, March 30th, 2012 at 11:00pm (EST), and is part of Rose's second series on the brain, Brain Series II. In this series, Rose and his co-host, Dr. Eric Kandel of Columbia University (Nobel Laureate and Howard Hughes Medical Investigator), interview prominent researchers to examine different subjects relating to the brain.Mr. Danny Hurley, who was diagnosed with schizophrenia in 1998, was first to be interviewed in this episode. Mr. Hurley was formerly a Bioengineering graduate student at the University of Pittsburgh and member of the Center for the Neural Basis of Cognition. He shared his story and insights into his illness, lending impetus to a conversation on the major schizophrenia research findings made by the scientists present, including Dr. David A. Lewis, Professor and Chair of the Department of Psychiatry at the University of Pittsburgh. The group also included Dr. Steven M. Paul of Weill Cornell Medical College, Dr. Cornelia Bargmann of Rockefeller University, and Dr. Judith L. Rapoport who is a Senior Investigator with the NIH.
Click here to watch the full episode online.
Levels of cannabinoid 1 receptor (CB1R) mRNA and protein, which are expressed most heavily in the cholecystokinin class of γ-aminobutyric acid (GABA) neurons, are lower in the dorsolateral prefrontal cortex (DLPFC) in schizophrenia, and the magnitude of these differences is strongly correlated with that for glutamic acid decarboxylase (GAD67) mRNA, a synthesizing enzyme for GABA. However, whether this correlation reflects a cause-effect relationship is unknown. Using quantitative in situ hybridization, we measured CB1R, GAD67, and diacylglycerol lipase alpha (DAGLα; the synthesizing enzyme for the endocannabinoid 2-arachidonoylglycerol) mRNA levels in the medial prefrontal cortex of genetically-engineered GAD67 heterozygous (GAD67+/-), CB1R heterozygous (CB1R+/-), CB1R knockout (CB1R-/-), and matched wild-type mice. In GAD67+/- mice, GAD67 and CB1R mRNA levels were significantly reduced by 37% and 16%, respectively, relative to wild-type mice (see Figure) and were significantly correlated across animals (r=0.61; p=0.01). In contrast, GAD67 mRNA levels were unaltered in CB1R+/- and CB1R-/- mice. Expression of DAGLα mRNA, which is not altered in schizophrenia, was also not altered in any of the genetically-engineered mice. The findings that reduced GAD67 mRNA expression can induce lower CB1R mRNA expression support the hypothesis that lower cortical levels of CB1Rs in schizophrenia may partially compensate for deficient GAD67-mediated GABA synthesis by reducing endogenous cannabinoid suppression of GABA release.
Eggan SM, Lazarus MS, Stoyak SR, Volk DW, Glausier JR, Huang J, Lewis DA: Cortical GAD67 deficiency results in lower cannabinoid 1 receptor mRNA expression: Implications for schizophrenia. Biol Psychiatry 71:114-119, 2012.
Reductions in dendritic arbor length and complexity are among the most consistently replicated changes in neuronal structure in post mortem studies of cerebral cortical samples from subjects with schizophrenia; however, the underlying molecular mechanisms have not been identified. This study is the first to identify an alteration in a regulatory protein which is known to promote both dendritic length and arborization in developing neurons, Kalirin-9. We found Kalirin-9 expression to be paradoxically increased in schizophrenia (Figure). We followed up this observation by overexpressing Kalirin-9 in mature primary neuronal cultures, causing reduced dendritic length and complexity. Kalirin-9 overexpression represents a potential mechanism for dendritic changes seen in schizophrenia.
Deo AJ, Cahill ME, Li S, Goldszer I, Henteleff R, VanLeeuwen JE, Rafalovich I, Gao R, Stachowski EK, Sampson AR, Lewis DA, Penzes P, Sweet RA: Increased expression of kalirin-9 in the auditory cortex of schizophrenia subjects: Its role in dendritic pathology. Neurobiol Dis, in press.
Depolarization-induced suppression of inhibition (DSI) is a prevailing form of endocannabinoid signalling. However, several discrepancies have arisen regarding the roles played by the two major brain endocannabinoids, 2-arachidonoylglycerol (2-AG) and anandamide, in mediating DSI. Here we studied endocannabinoid signalling in the prefrontal cortex (PFC), where several components of the endocannabinoid system have been identified, but endocannabinoid signalling remains largely unexplored. In voltage clamp recordings from mouse PFC pyramidal neurons, depolarizing steps significantly suppressed IPSCs induced by application of the cholinergic agonist carbachol. DSI in PFC neurons was abolished by extra- or intracellular application of tetrahydrolipstatin (THL), an inhibitor of the 2-AG synthesis enzyme diacylglycerol lipase (DAGL). Moreover, DSI was enhanced by inhibiting 2-AG degradation, but was unaffected by inhibiting anandamide degradation. THL, however, may affect other enzymes of lipid metabolism and does not selectively target the α (DAGLα) or β (DAGLβ) isoforms of DAGL. Therefore, we studied DSI in the PFC of DAGLα −/− and DAGLβ −/− mice generated via insertional mutagenesis by gene-trapping with retroviral vectors. Gene trapping strongly reduced DAGLα or DAGLβ mRNA levels in a locus-specific manner. In DAGLα −/− mice cortical levels of 2-AG were significantly decreased and DSI was completely abolished, whereas DAGLβ deficiency did not alter cortical 2-AG levels or DSI (Figure). Importantly, cortical levels of anandamide were not significantly affected inDAGLα −/− orDAGLβ−/−mice. The chronic decrease of 2-AGlevels in DAGLα −/− mice did not globally alter inhibitory transmission or the response of cannabinoid-sensitive synapses to cannabinoid receptor stimulation, although it altered some intrinsic membrane properties. Finally, we found that repetitive action potential firing of PFC pyramidal neurons suppressed synaptic inhibition in a DAGLα-dependent manner. These results show that DSI is a prominent form of endocannabinoid signalling in PFC circuits. Moreover, the close agreement between our pharmacological and genetic studies indicates that 2-AG synthesized by postsynaptic DAGLα mediates DSI in PFC neurons.
Yoshino H, Miyamae T, Hansen G, Zambrowicz B, Flynn M, Pedicord D, Blat Y, Westphal RS, Zaczek R, Lewis DA, Gonzalez-Burgos G: Postsynaptic diacylglycerol lipase alpha mediates retrograde endocannabinoid suppression of inhibition in mouse prefrontal cortex. J Physiol, ePub August 1, 2011.
Certain cognitive deficits in schizophrenia have been linked to dysfunction of prefrontal cortical (PFC) g-aminobutyric acid (GABA) neurons and appear neurodevelopmental in nature. Since opioids suppress GABA neuron activity, we conducted the first study to determine 1) whether the μ opioid receptor (MOR), δ opioid receptor (DOR), and opioid ligand proenkephalin are altered in the PFC of a large cohort of schizophrenia subjects and 2) the postnatal developmental trajectory in monkey PFC of opioid markers that are altered in schizophrenia. We used quantitative polymerase chain reaction to measure mRNA levels from 42 schizophrenia and 42 matched healthy comparison subjects; 18 monkeys chronically exposed to haloperidol, olanzapine, or placebo; and 49 monkeys aged 1 week to 11.5 years. We found higher levels for MOR mRNA (127%) in schizophrenia but no differences in DOR or roenkephalin mRNAs. Elevated MOR mRNA levels in schizophrenia did not appear to be explained by substance abuse, psychotropic medications, or illness chronicity. Finally, MOR mRNA levels declined through early postnatal development, stabilized shortly before adolescence and increased across adulthood in monkey PFC. Because MOR activation suppresses GABA release from axon terminals and hyperpolarizes the cell body (reducing responsiveness to excitatory input), higher MOR mRNA levels in schizophrenia may contribute to suppressed PFC GABA neurotransmission (Figure). These abnormalities may reflect alterations in the postnatal developmental trajectory of MOR signaling.
Volk, DW, Radchenkova PV, Walker EM, Sengupta EJ, Lewis DA: Cortical opioid markers in schizophrenia and across postnatal development. Cereb Cortex, ePub August 1, 2011.
For 16 undergraduate students, the CCNMD Undergraduate Final Presentations, held on July 28-29, marked the end of the CCNMD Undergraduate Research Fellowship's ten week summer program.
During the summer, each Fellow conducted a research project, participated in the clinical exposure program, and attended weekly teaching sessions on research strategies, ethics and career development. As a culmination of their work, each Fellow presented their study and responded to questions from an audience of faculty, post-doctoral fellows, graduate students, and peers. Audience members agreed that the overall quality of the presentations was extremely high. Most of the Fellows will be continuing their research into the next academic year.
Congratulations to all the Fellows!
More information on the Fellowship program can be found here.
Levels of mRNA for the α1 subunit of the GABAA receptor, which is present in 60% of cortical GABAA receptors, have been reported to be lower in layer 3 of the prefrontal cortex in subjects with schizophrenia. This subunit is expressed in both pyramidal cells and interneurons, and thus lower α1 subunit levels in each cell population would have opposite effects on net cortical excitation. We used dual-label in situ hybridization to quantify GABAA α1 subunit mRNA expression in calcium/calmodulin-dependent kinase II α (CaMKIIα)-containing pyramidal cells (circles in panel A) and glutamic acid decarboxylase 65 kDa (GAD65)-containing interneurons (circles in panel B) in layer 3 of the PFC from matched schizophrenia and healthy comparison subjects. In subjects with schizophrenia, mean GABA A α1 subunit mRNA expression was significantly 40% lower in pyramidal cells (panel C), but was not altered in interneurons (panel D). Lower α1 subunit mRNA expression in pyramidal cells was not attributable to potential confounding factors, and thus appeared to reflect the disease process of schizophrenia. These results suggest that pyramidal cell inhibition is reduced in schizophrenia, whereas inhibition of GABA neurons is maintained. The cell type specificity of these findings may reflect a compensatory response to enhance layer 3 pyramidal cell activity in the face of diminished excitatory drive associated with the lower dendritic spine density on these neurons.
Glausier JR and Lewis DA: Selective Pyramidal Cell Reduction of GABAA Receptor a1 Subunit Expression in Schizophrenia. Neuropsychopharmacology, in press.
Cognitive deficits in schizophrenia are associated with altered activity of the dorsolateral prefrontal cortex (DLPFC) which has been attributed to lower expression of the 67 kDa isoform of glutamic acid decarboxylase (GAD67), the major GABA-synthesizing enzyme. However, little is known about the relationship of prefrontal GAD67 mRNA levels and illness severity, translation of the transcript into protein, or protein levels in axon terminals, the key site of GABA production and function. Quantitative PCR was used to measure GAD67 mRNA levels in the DLPFC from 42 subjects with schizophrenia and 42 matched comparison subjects. Western blotting was used to quantify tissue levels of GAD67 protein in a subset of subjects where potential confounds of protein measures were controlled. Multi-label, confocal immunofluorescence was used to quantify GAD67 protein levels in the axon terminals of parvalbumin-containing GABA neurons, known to have low levels of GAD67 mRNA in schizophrenia. GAD67 mRNA levels were significantly 15% lower in schizophrenia subjects, but transcript levels were not associated with predictors or measures of disease severity or chronicity. In schizophrenia subjects, GAD67 protein levels were significantly 10% lower in total gray matter and 49% lower in parvalbumin axon terminals. These findings indicate that lower GAD67 mRNA expression is common in schizophrenia, is not a consequence of having the illness, and leads to less translation of the protein, especially in the axon terminals of parvalbumin-containing neurons. As summarized in the figure, lower synthesis of GABA (red dots) in parvalbumin neurons is thought to lead to impaired inhibition of DLPFC pyramidal neurons reduced gamma band power, and impaired cognition in schizophrenia.
Curley AA, Arion D, Volk DW, Asafu-Adjei JK, Sampson AR, Fish KN, Lewis DA: Cortical deficits of glutamic acid decarboxylase 67 expression in schizophrenia: Clinical, protein, and cell type-specific features. Am J Psychiatry, in press.
Dr. David Volk was recently selected to receive a Young Investigator Travel Award to attend the 2011 International Congress on Schizophrenia Research. At the Congress, Dr. Volk presented his research on Cortical Mu Opioid Receptor mRNA Expression in Schizophrenia and Across Development. CONGRATULATIONS TO DAVID!
| Franklyn Boothe Megan Gray Tyler Hein Joseph Kern Michael Kitchens |
Yongbin Kwon Audrey Latimore Emily Maier Valerie Michael Cameron Olezene |
Brent Oliveros Wasiq Sheikh Ben Siegel Ryan Stolakis Thomas Wozny |
Congratulations to these students who were selected through a competitive application process. This summer they will work closely with faculty investigators on a guided independent research project. More information on the Fellowship program can be found here.
The contribution of differences in GABA synthesis and reuptake in axon boutons to cell type-specific functions is unknown. GABA is synthesized within boutons by GAD65 and GAD67, while GAT1 is responsible for GABA reuptake. Using an imaging methodology capable of determining the colocalization frequency of different immunocytochemical labels in the same bouton, and the quantification of the fluorescence intensity of each label in these same structures, we assessed the bouton levels of GAD65, GAD67, and GAT1 in parvalbumin expressing chandelier (PVch) and basket (PVb) neurons, and cannabinoid receptor 1 expressing basket (CB1rb) neurons in the monkey prefrontal cortex. We show that PVch boutons almost exclusively contained GAD67, relative to GAD65, whereas CB1rb boutons contained mostly GAD65. In contrast, both GAD65 and GAD67 were easily detected in PVb boutons (Figure). Furthermore, in comparison to PVch boutons, CB1rb boutons expressed low to undetectable levels of GAT1. Our findings provide a new basis for the distinctive functional roles of these perisomatic-innervating interneurons in cortical circuits. In addition, they strongly suggest that altered levels of GAD67 or GAD65, as seen in some psychiatric diseases, would have cell type-specific consequences on the modulation of GABA neurotransmission.Fish KN, Sweet RA, Lewis DA: Differential distribution of proteins regulating GABA synthesis and reuptake in axon terminals of subpopulations of cortical interneurons. Cereb Cortex, in press.
In the dorsolateral prefrontal cortex (DLPFC), these alterations include lower transcript expression of glutamic acid decarboxylase (GAD67) and somatostatin (SST), a neuropeptide expressed in the Martinotti subpopulation of GABA neurons whose axons innervate the distal apical dendrites of pyramidal neurons. However, whether the alterations in SST-containing interneurons are associated with changes in post-synaptic receptors for SST has not been examined. Thus, we used in situ hybridization to quantify the mRNA expression levels of SST receptors subtype 1 (SSTR1) and subtype 2 (SSTR2) in DLPFC area 9 from 23 matched pairs of subjects with schizophrenia and normal comparison subjects. We also assessed the effects of potential confounding variables within the human subjects and in brain specimens from macaque monkeys with long term exposure to antipsychotic drugs. SSTR1 mRNA levels did not differ between subject groups. In contrast, mean cortical SSTR2 mRNA levels were significantly 19% lower in the subjects with schizophrenia (Figure). Laminar and cellular level analyses revealed that lower SSTR2 mRNA levels were localized to pyramidal cells in the cortical layers 5-6. Levels of SSTR2 mRNA were lower in monkeys exposed chronically to low dose haloperidol, but no differences were observed in monkeys exposed to higher doses of haloperidol or to olanzapine or between subjects with schizophrenia on or off antipsychotic medications at the time of death. These findings suggest that lower SST mRNA expression in schizophrenia is accompanied by reduced levels of SSTR2 mRNA selectively in pyramidal neurons in layers 5-6. Together, these findings suggest converging pre- and post-synaptic mechanisms to reduce inhibitory inputs to pyramidal neurons in the infragranular layers of the DLPFC.Beneyto M, Morris HM, Rovensky KC, Lewis DA: Lamina- and cell-specific alterations in cortical somatostatin receptor 2 expression in schizophrenia. Neuropharmacology, in press.
- Complete Application Form
- An Official Transcript from High School institution (for freshman applicants)
- An Official Transcript from College or University (complete up to, and including the Fall term)
- Brief Personal Statement
- Two Letters of Recommendation
The culmination of over 20 years of intense neuroscience studies at the TNP has expanded the range and depth of the team’s reach, and opened new, breath-taking windows into the mysteries of the brain. Tom Insel, the director of the National Institute for Mental Health, remarks that the research featured in this article "provides something this field really needed: a framework for linking observations at the molecular, cellular and systems levels. We haven't had a story that crossed those levels of explanation before."
The advances in brain research accomplished by the TNP require the expertise and cooperation of every one of its members. Their hard work has been critical to the innovative efforts for improving the lives of those who suffer from schizophrenia as well as their families.
The full article can be found at www.Nature.com.
The ACNP annually selects a group of illustrious young scientists in the field of neuropsychopharmacology to be a part of its Travel Award program. As an awardee, David will have the opportunity to attend the ACNP’s Annual Meeting in December 2010. The meeting encompasses an exceptional scientific program in clinical and basic research; discussions of the latest developments in psychopharmacology; and interactions with researchers and scientists of international distinction. This year the ACNP had a record number of highly qualified applicants and the Education & Training Review Committee experienced great difficulty in determining the final group. This is a clear testament to Dr. Volk’s standing as a young scientist who has a great deal to contribute to the field. CONGRATULATIONS TO DAVID!
Dr. Raymond Cho provides new research findings in the management of patients with schizophrenia, including brain oscillations and cognition. This video appears in Physician Resources on the UPMC website, helping viewers to: recognize the importance of cognitive impairments as a core feature of schizophrenia and a critical determinant of functional outcome in the illness; recognize the potential role of brain oscillations and their role in the pathophysiology of schizophrenia; describe potential pharmacotherapeutic mechanisms for restoring neural oscillatory function in schizophrenia.
Click here to see the video: Brain Oscillations and Cognition in Schizophrenia
27th Annual Schizophrenia Conference
Friday, December 10, 2010
Sheraton Station Square Hotel
Pittsburgh, PA
Course Director:
K.N. Roy Chengappa, MD
The Pittsburgh Schizophrenia Conference is an annual meeting at which the advances in schizophrenia research are reviewed by leading international experts in the field. This year’s meeting will cover a range of topics, including electrical activity and oscillations in the brain and brain imaging research. Furthermore, ways to get back decades of life lost in persons with schizophrenia using approaches to reduce medical co-morbidity such as reducing body weight will also be reviewed. A patient and family perspective regarding patient centered medicine as it applies to people with severe mental illness will be discussed in a panel format.
Who Should Attend
The conference is designed to disseminate the latest research findings to a wide audience: psychiatrists and other mental health clinicians, including nurses, social workers, psychologists, service coordinators, researchers, patients and their relatives, mental health policy administrators and others who wish to keep abreast of etiologic and treatment research in schizophrenia.
Objectives
At the conclusion of the program, participants should be able to:
- Describe electrical oscillations of the brain and cognitive disturbance in schizophrenia.
- Review brain neuro-receptor imaging research especially as it relates to the dopamine system, and how the neurochemical GABA system may be involved in the clinical symptoms of schizophrenia.
- Consider behavioral strategies aimed at modifying the diet and life-styles of persons with schizophrenia to reduce the incidence of premature heart disease and diabetes.
- Review from a patient and family perspective what it means to have physical illnesses along with mental illness and how best to manage these co-occurring conditions.
- Consider pragmatic psychosocial treatments and how these may be applied in clinical practice.
UPMC Health System Western Psychiatric Institute & Clinic;
Services and Research for Recovery in Serious Mental Illness;
Mental Health Conference Planning;
University of Pittsburgh School of Medicine;
Center for Continuing Education in the Health Sciences
Schizophrenia may involve hypofunction of NMDA receptor-mediated signaling, and dysfunction in parvalbumin-positive fast-spiking (FS) GABA neurons that may cause abnormal gamma oscillations. It was recently hypothesized that prefrontal cortex (PFC) FS neuron activity is highly dependent on NMDA receptor activation and that, consequently, FS neuron dysfunction in schizophrenia is secondary to NMDA receptor hypofunction. However, NMDA receptors are abundant in synapses onto PFC pyramidal neurons, thus a key question is whether FS neuron or pyramidal cell activation is more dependent on NMDA receptors. We examined the AMPA receptor and NMDA receptor contribution to synaptic activation of FS neurons and pyramidal cells in the PFC of adult mice. In FS neurons, EPSCs had fast decay and weak NMDA receptor contribution whereas in pyramidal cells EPSCs were significantly prolonged by NMDA receptor-mediated currents. Moreover, the AMPA receptor/NMDA receptor EPSC ratio was higher in FS cells (Figure). NMDA receptor antagonists decreased EPSPs and EPSP-spike coupling more strongly in pyramidal cells than in FS neurons, showing that FS neuron activation is less NMDA receptor-dependent than pyramidal cell excitation. The rapid EPSP-spike coupling produced by fast-decaying EPSCs in FS cells may be important for network mechanisms of gamma oscillations based on feedback inhibition. To test this possibility, we used simulations in a computational network of reciprocally-connected FS neurons and pyramidal cells and found that brief AMPA receptor-mediated FS neuron activation is crucial to synchronize, via feedback inhibition, pyramidal cells in the gamma frequency band. Our results raise interesting questions about the mechanisms that might link NMDA receptor hypofunction to alterations of FS neurons in schizophrenia.Rotaru DC, Yoshino H, Lewis DA, Ermentrout GB, Gonzalez-Burgos G: Glutamate receptor subtypes mediating synaptic activation of prefrontal cortex neurons: relevance for schizophrenia. J Neurosci, in press.
Dysfunction of the dorsolateral prefrontal cortex (DLPFC) in schizophrenia is associated with lamina-specific alterations in particular subpopulations of interneurons. In pyramidal cells, postsynaptic GABAA receptors containing different subunits are inserted preferentially in distinct subcellular locations targeted by inputs from specific interneuron subpopulations. We used in situ hybridization to quantify the laminar expression of α1, α2, α3, and α5 subunit, and of β1-3 subunit, mRNAs in the DLFPC of schizophrenia and matched normal comparison subjects. In subjects with schizophrenia, mean GABAA α1 mRNA expression was 17% lower in layers 3-4, α2 expression was 14% higher in layer 2, α5 expression was 15% lower in layer 4, and α3 expression did not differ relative to comparison subjects. The mRNA expression of β2, which preferentially assembles with α1 subunits, was also 20% lower in layers 3-4, whereas β1 and β3 mRNA levels were not altered in schizophrenia. These expression differences were not attributable to medication effects or other potential confounds. These findings suggest that GABA neurotransmission in the DLPFC is altered at the postsynaptic level in a receptor subunit- and layer-specific manner in subjects with schizophrenia (see figure), and support the hypothesis that GABA neurotransmission in this illness is predominantly impaired in certain cortical microcircuits.
Beneyto M, Abbott A, Hashimoto T, Lewis DA: Lamina-specific alterations in cortical GABAA receptor subunit expression in schizophrenia. Cereb Cortex, ePub September 15, 2010.
Exposure to cannabis impairs cognitive functions reliant on the circuitry of the dorsolateral prefrontal cortex (DLPFC) and increases the risk of schizophrenia. The actions of cannabis are mediated via the brain cannabinoid 1 receptor (CB1R), which in rodents is heavily localized to the axon terminals of cortical GABA basket neurons that contain cholecystokinin (CCK). Differences in the laminar distribution of CB1R-immunoreactive (IR) axons have been reported between rodent and monkey neocortex, suggesting that the cell type(s) containing CB1Rs, and the synaptic targets of CB1R-IR axon terminals, may differ across species; however, neither the relationship of CB1Rs to CCK-containing interneurons, nor the postsynaptic targets of CB1R and CCK axon terminals, have been examined in primate DLPFC. Consequently, we compared the distribution patterns of CB1R- and CCK-IR structures, determined the proportions of CB1R and CCK neurons that were dual-labeled, and identified the synaptic types and postsynaptic targets of CB1R- and CCK-IR axon terminals in macaque monkey DLPFC. By light microscopy, CB1R- and CCK-IR axons exhibited a similar laminar distribution, with their greatest densities in layer 4. Dual-label fluorescence experiments demonstrated that 91% of CB1R-IR neurons were immunopositive for CCK, whereas only 51% of CCK-IR neurons were immunopositive for CB1R. By electron microscopy, all synapses formed by CB1R-IR axon terminals were symmetric, whereas CCK-IR axon terminals formed both symmetric (88%) and asymmetric (12%) synapses. The primary postsynaptic target of both CB1R- and CCK-IR axon terminals forming symmetric synapses was dendritic shafts (81-88%), with the remainder targeting cell bodies or dendritic spines. As shown in the figure, CB1R-IR axon terminals (CB1Rt) formed symmetric synapses (arrows) onto small (A) and large (D) unlabeled dendritic shafts (ud), onto (B) a CB1R-IR dendritic shaft (CB1Rd), and onto (C) an unlabeled dendritic spine (us). In addition, as shown in panel E CB1R-IR axons formed “basket-like” appositions (white arrows) around an unlabeled cell body (ad = apical dendrite, n = nucleus). Thus, despite species differences in laminar distribution, CB1Rs are principally localized to CCK basket neuron axons in both rodent neocortex and monkey DLPFC. These axons target the perisomatic region of pyramidal neurons, providing a potential anatomical substrate for the impaired function of the DLPFC associated with cannabis use and schizophrenia. Eggan SM, Melchitzky DS, Sesack SR, Fish KN, Lewis DA: Relationship of cannabinoid CB1 receptor and cholecystokinin immunoreactivity in monkey dorsolateral prefrontal cortex. Neuroscience 169: 1651-1661, 2010.
Disturbances in markers of cortical GABA neurotransmission are a common finding in schizophrenia. The nature of GABA neurotransmission (hyperpolarizing or depolarizing) depends on the local intracellular chloride concentration. In the central nervous system, the intracellular chloride level is determined by the activity of two cation-chloride transporters, NKCC1 and KCC2. The activities of these transporters are in turn regulated by a network of serine-threonine kinases that includes OXSR1, STK39 and the WNK kinases WNK1, 3 and 4. We used real-time qPCR to compare the levels of NKCC1, KCC2, OXSR1, STK39, WNK1, WNK3 and WNK4 transcripts in prefrontal cortex area 9 from 42 subjects with schizophrenia and 42 matched normal comparison subjects, and from 18 macaque monkeys chronically exposed to haloperidol, olanzapine, or sham. OXSR1 and WNK3 transcripts were substantially over-expressed in schizophrenia relative to comparison subjects. In contrast, NKCC1, KCC2, STK39, WNK1 and WNK4 transcript levels did not differ between subject groups. OXSR1 and WNK3 transcript expression levels were not changed in antipsychotic-exposed monkeys and were not affected by potential confounding factors in the subjects with schizophrenia. As illustrated in panel A, in normal adult neurons, intracellular chloride concentration is low due to low levels of NKCC1 and high levels of KCC2. The binding of GABA to GABA-A receptors triggers chloride entry (chloride flow is represented by green arrows) and hyperpolarization. In schizophrenia (panel B) increased OXSR1 and WNK3-1 kinase levels lead to increased phosphorylation (blue P) and consequently increased NKCC1 activity and decreased KCC2 activity, producing a greater intracellular chloride concentration. Thus, when GABA-A receptors are activated chloride influx is reduced (or perhaps reversed) and the nature of GABA neurotransmission is altered.
Arion D and Lewis DA: Altered expression of regulators of the cortical choloride transporters NKCC1 and KCC2 in schizophrenia. Arch Gen Psychiatry, in press.
Certain cognitive deficits in individuals with schizophrenia have been linked to disturbed GABA and glutamate neurotransmission in the prefrontal cortex (PFC). Thus, it is important to understand how the mechanisms that regulate GABA and glutamate neurotransmission are altered in schizophrenia. For example, group I metabotropic glutamate receptors (mGluR1α and mGluR5) modulate both GABA and glutamate systems. In addition, regulator of G protein signaling 4 (RGS4) reduces intracellular signaling through several different G protein-coupled receptors, including group I mGluR. Finally, the endocannabinoid system plays an important role in regulating GABA and glutamate neurotransmission; the status of endocannabinoid ligands, such as 2-arachidonoylglycerol (2-AG), can be inferred, in part, through measures of diacylglycerol lipase and monoglyceride lipase, which synthesize and degrade 2-AG, respectively. We used quantitative PCR to measure mRNA levels for group I mGluR, RGS4, and markers of the endocannabinoid system in PFC area 9 from 42 schizophrenia subjects and matched normal comparison subjects. Schizophrenia subjects had higher mRNA levels for mGluR1α and lower mRNA levels for RGS4, and these differences did not appear to be attributable to antipsychotic medications or other potential confounds. In contrast, no differences between subject groups were found in mRNA levels for endocannabinoid synthesizing and metabolizing enzymes. Together, higher mGluR1α and lower RGS4 mRNA levels may represent a disturbed “molecular hub” in schizophrenia that may disrupt the function of PFC cortical networks. For example, as shown in the figure, under normal conditions, activation of mGluR1α results in long-term potentiation of NMDA and AMPA receptors and activation of DAGL which leads to synthesis of 2-AG and suppression of GABA release from nearby inhibitory axon terminals that contain the CB1 receptor. In addition, RGS4 reduces signaling through several different G protein-coupled receptors, including group I mGluR, opioid, serotonin, and dopamine receptors. In schizophrenia, higher mGluR1α and lower RGS4 mRNA levels suggest the presence of enhanced signaling through mGluR1α. Higher mGluR1α signaling may have diverse effects on multiple components of neural transmission in schizophrenia (red font), including greater long-term potentiation of NMDA and AMPA receptors, enhanced 2-AG synthesis, and greater suppression of GABA release from inhibitory axon terminals that contain the CB1 receptor. In addition, lower RGS4 levels may result in less inhibition of several classes of G protein-coupled receptors (yellow font).
Volk DW, Eggan SM, Lewis DA: Alterations in Metabotropic Glutamate Receptor 1α and Regulator of G Protein Signaling 4 in the Prefrontal Cortex in Schizophrenia. Am J Psychiatry, in press.
Schizophrenia may involve hypofunction of NMDA receptor-mediated signaling, and dysfunction in parvalbumin-positive fast-spiking (FS) GABA neurons that may cause abnormal gamma oscillations. It was recently hypothesized that prefrontal cortex (PFC) FS neuron activity is highly dependent on NMDA receptor activation and that, consequently, FS neuron dysfunction in schizophrenia is secondary to NMDA receptor hypofunction. However, NMDA receptors are abundant in synapses onto PFC pyramidal neurons, thus a key question is whether FS neuron or pyramidal cell activation is more dependent on NMDA receptors. We examined the AMPA receptor and NMDA receptor contribution to synaptic activation of FS neurons and pyramidal cells in the PFC of adult mice. In FS neurons, EPSCs had fast decay and weak NMDA receptor contribution whereas in pyramidal cells EPSCs were significantly prolonged by NMDA receptor-mediated currents. Moreover, the AMPA receptor/NMDA receptor EPSC ratio was higher in FS cells (Figure). NMDA receptor antagonists decreased EPSPs and EPSP-spike coupling more strongly in pyramidal cells than in FS neurons, showing that FS neuron activation is less NMDA receptor-dependent than pyramidal cell excitation. The rapid EPSP-spike coupling produced by fast-decaying EPSCs in FS cells may be important for network mechanisms of gamma oscillations based on feedback inhibition. To test this possibility, we used simulations in a computational network of reciprocally-connected FS neurons and pyramidal cells and found that brief AMPA receptor-mediated FS neuron activation is crucial to synchronize, via feedback inhibition, pyramidal cells in the gamma frequency band. Our results raise interesting questions about the mechanisms that might link NMDA receptor hypofunction to alterations of FS neurons in schizophrenia.Rotaru DC, Yoshino H, Lewis DA, Ermentrout GB, Gonzalez-Burgos G: Glutamate receptor subtypes mediating synaptic activation of prefrontal cortex neurons: relevance for schizophrenia. J Neurosci, in press.
Dr. Stephen Eggan, Senior Research Principal; Dr. Jill Glausier, Post-Doctoral Scholar; and Gil Hoftman, MD/PhD Student Researcher, were all named as finalists for the Society of Biological Psychiatry (SOBP) Top Poster Award. Being named a finalist in this category meant that each of their abstracts ranked among the top 30 submissions out of the over 650 abstracts the SOBP reviewed for this years’ Annual Conference. The 30 finalists’ posters will be judged by a selection committee at the 65th Annual SOBP Conference, to be held in New Orleans, LA, May 20-22, 2010. The Top Poster Award will be presented to the top posters in basic research and clinical/translational research at the. The award winners will be announced on the SOBP website and in the newsletter. Congratulations to Stephen, Jill, and Gil for having submitted posters that ranked among the top 30 for this years’s SOBP annual meeting!
| Elizabeth Anger Jennifer Ciuchta Christian Frable Jan Kalkus Sagar Kamprath |
KC McTish Nikita Malcom Laetitia Ngamassi Melanie Peterson Erin Walker |
The CCNMD Undergraduate Research Fellowship provides highly talented undergraduate students with early-career, hands-on engagement in cutting edge neuroscience research. Over the course of the summer, fellows work under the mentorship of one of the Center’s accomplished clinical or basic neuroscientists to develop a longitudinal, independent research project. The overall aim of the CCNMD Undergraduate Fellowship is to prepare talented students for doctoral training leading to a career in mental health research. More information on the Fellowship program can be found at http://www.ccnmd.pitt.edu/Pages/Training/ugradover.html.
Dr. David Lewis will present as a featured speaker at the Cold Springs Harbor Workshop on Schizophrenia and Related Disorders, June 9 – 15, 2010.
“This workshop will provide students with the most current understanding of the molecular, cellular and neural systems underlying the disturbances in brain function in these devastating illnesses. During the 7-day workshop, students will learn about the clinical aspects of schizophrenia, schizoaffective disorder and bipolar disorder as well as explore in detail the genetic and neurobiological underpinnings of these complex psychiatric disorders. The Workshop will include sessions focused on: The Clinical Syndrome, Basic Neurobiology, Cognitive Neuroscience, Neuroimaging, Genetics and Genomics, Endophenotypes, and Gene Expression and Gene Modulation. A diverse faculty will bring the most up-to-date results and theories to the students, making this Workshop a valuable resource for young researchers starting out in this fast-moving and expansive field.”
More Information is available at http://meetings.cshl.edu/courses/c-schiz10.shtml.
Converging lines of evidence indicate that schizophrenia is characterized by impairments of synaptic machinery within cerebral cortical circuits. Efforts to localize these alterations in brain tissue from subjects with schizophrenia have frequently been limited to the quantification of structures that are non-selectively identified (e.g. dendritic spines labeled in Golgi preparations, axon boutons labeled with synaptophysin), or to quantification of proteins using methods unable to resolve relevant cellular compartments. Multiple label fluorescence confocal microscopy represents a means to circumvent many of these limitations, by concurrently extracting information regarding the number, morphology, and relative protein content of synaptic structures. An important adaptation required for studies of human disease is coupling this approach to stereologic methods for systematic random sampling of relevant brain regions. In this review article we consider the application of multiple label fluorescence confocal microscopy to the mapping of synaptic alterations in subjects with schizophrenia and describe the application of a novel, readily automated, iterative intensity/morphological segmentation algorithm for the extraction of information regarding synaptic structure number, size, and relative protein level from tissue sections obtained using unbiased stereological principles of sampling. In this context, we illustrate the examination of pre- and post-synaptic structures within excitatory and inhibitory circuits of the cerebral cortex. For example, the figure above shows human primary auditory cortex tissue labeled for synaptophysin (Synph, green), vesicular glutamate transporter 2 (VGlut2; blue), and vesicular glutamate transporter (VGlut1; red). In panels A-D, arrows demonstrate colocalization between synaptophysin and either VGlut1 or VGlut2. Panel E shows VGlut2 and synaptophysin fluorescence intensities extracted from mask objects of the VGlut1-immunoreactive boutons in the micrographs shown in panels A-D, demonstrating that quantitative data reflecting the degree of colocalization are readily extracted. Bar = 5 µm.Sweet RA, Fish KN and Lewis DA: Mapping synaptic pathology within cerebral cortical circuits in subjects with schizophrenia. Front. Hum. Neurosci 4: 44, 2010.
May 14, 2010
Sheraton Station Square Hotel
Pittsburgh, PA
For more information: http://www.wpic.pitt.edu/OERP/conferences
Spine density on the basilar dendrites of pyramidal neurons is lower in layer 3, but not in layers 5-6, in the dorsolateral prefrontal cortex (DLPFC) of subjects with schizophrenia. The expression of CDC42, which promotes spine formation, is also lower in thse subjects; however, the deficit in CDC42 mRNA is present across layers 3-6, suggesting that other lamina-specific molecular alterations are critical for the appearance of the spine deficits in the illness. The CDC42 effector protein 3 (CDC42EP3) is preferentially expressed in human DLPFC layers 2 and 3, and appears to assemble septin filaments in spine necks. We found that the expression of CDC42EP3 mRNA was significantly increased by 19.7%, and SEPT7 mRNA was significantly decreased by 6.9% in subjects with schizophrenia. These findings suggest the following model (panel) for spine dysfunction in schizophrenia. (A) CDC42EP3 binds to septins via its BD3 domain, inducing the assembly of septin filaments. The inactive form of CDC42 cannot bind to the CRIB domain of CDC42EP3. (B) The activated form of CDC42 binds to CDC42EP3 via its CRIB domain and inhibits CDC42EP3, disrupting the septin filament assembly. (C top) In the normal state, CDC42EP3 consolidates the septin 5/7/11 complex in spine necks, providing a barrier for molecular diffusion with the parent dendrite. (C middle) Transient activation of CDC42 by glutamate stimulation inhibits the CDC42EP3-mediated assembly of the septin barrier (C bottom) enabling postsynaptic molecules to enter the spine for synaptic potentiation. (D top) In schizophrenia, decreased mRNA expression of SEPT7 contributes to an impaired septin barrier function at the spine neck, limiting the retention of postsynaptic molecules, such as cytoskeletal proteins and/or second messengers, which are critical for spine structure and function in the spine head. (D middle) Furthermore, lower levels of CDC42 and increased levels of CDC42EP3 lead to a reduced capacity for glutamatergic stimuli to produce opening of the septin barrier, impairing synaptic plasticity and contributing to spine loss (D bottom).Ide M and Lewis DA: Altered cortical CDC42 signaling pathways in schizophrenia: Implications for dendritic spine deficits. Biol Psychiatry 68: 25-32, 2010.
Aging leads to a variety of morphological and functional changes in the brain, and is associated with cognitive decline and increased risk for neuropsychiatric and neurological disorders. In transcriptome studies of neuropsychiatric disorders in the human postmortem brain conducted by TNP faculty member Dr. Etienne Sibille, the largest source of biological variability has been subject age. Thus, the Sibille Laboratory undertook the project of fully characterizing the nature and extent of the gene expression correlates of aging. In line with the NIH requirement to make large-scale transcriptome data available to the broader scientific community, the Sibille Laboratory has recently made publicly available a newly developed interactive database for age effect on gene expression in the human brain. To search the database, users should enter at least one gene name, code, or keyword into the search tool. The database immediately provides large-scale gene expression data from two different cohorts across four areas of the human brain: prefrontal cortex BA9, prefrontal cortex BA47, anterior cingulate cortex, and amygdala. The user then selects any molecular probe listed to find the gene expression data in that brain region. The tool is designed to be used freely and publicly by any researcher interested in gene function in the human brain in the context of aging or neuropsychiatric disorders. To make citing the data easy, all corresponding original data citations are listed at the bottom of each gene report page.26th Annual Schizophrenia Conference
November 13, 2009
Sheraton Station Square Hotel, Pittsburgh, PA
Course Director:
K.N. Roy Chengappa, MD
The Pittsburgh Schizophrenia Conference is an annual meeting at which the advances in schizophrenia research are reviewed by leading international experts in the field. This year’s meeting will cover a range of topics, including electrical activity and oscillations in the brain and brain imaging research. Furthermore, ways to get back decades of life lost in persons with schizophrenia using approaches to reduce medical co-morbidity such as reducing body weight will also be reviewed. A patient and family perspective regarding patient centered medicine as it applies to people with severe mental illness will be discussed in a panel format. Presentations by the faculty awarded the 2009 Pittsburgh Schizophrenia Conference Award, and the Gerard Hogarty Research Excellence Prize will also take place during the meeting.
Who Should Attend
The conference is designed to disseminate the latest research findings to a wide audience: psychiatrists and other mental health clinicians, including nurses, social workers, psychologists, service coordinators, researchers, patients and their relatives, mental health policy administrators and others who wish to keep abreast of etiologic and treatment research in schizophrenia.
Objectives
At the conclusion of the program, participants should be able to:
- Describe electrical oscillations of the brain and cognitive disturbance in schizophrenia.
- Review brain neuro-receptor imaging research especially as it relates to the dopamine system, and how the neurochemical GABA system may be involved in the clinical symptoms of schizophrenia.
- Consider behavioral strategies aimed at modifying the diet and life-styles of persons with schizophrenia to reduce the incidence of premature heart disease and diabetes.
- Review from a patient and family perspective what it means to have physical illnesses along with mental illness and how best to manage these co-occurring conditions.
- Consider pragmatic psychosocial treatments and how these may be applied in clinical practice.
Presented by:
UPMC Health System Western Psychiatric Institute & Clinic;
Services and Research for Recovery in Serious Mental Illness;
Mental Health Conference Planning;
University of Pittsburgh School of Medicine;
Center for Continuing Education in the Health Sciences
Schizophrenia is a severe disorder that disrupts the function of multiple brain systems, resulting in impaired social and occupational functioning. The etiology and pathogenesis of schizophrenia appear to involve the interplay of a potentially large number of genetic liabilities and adverse environmental events that disrupt brain developmental pathways. In this Review, we discuss strategies for determining how particular common and core clinical features of the illness are associated with pathophysiology in certain circuits of the cerebral cortex. For example, impaired working memory and processing of auditory information in individuals with schizophrenia are attributable, at least in part, to specific pathological alterations in the dorsolateral prefrontal cortex and primary auditory cortex, respectively. These involve, but are not restricted to, disturbances in glutamate, GABA, and dopamine neurotransmission. For example, as illustrated in the figure, auditory cortical processing is initiated by projections from the medial geniculate nucleus of the thalamus. These projections are arranged tonotopically, (i.e., along a frequency gradient that is broadly tuned). The subsequent activation of a reciprocally connected isofrequency network of pyramidal cells (light blue) within layer 3 selectively amplifies a narrower preferred frequency, refining the thalamic tuning curve. Densities of dendritic spines and axonal boutons are reduced in deep layer 3 of subjects with schizophrenia, potentially limiting activation and current flow in the pyramidal cell network. Pyramidal cells are co-tuned (i.e., receive concurrent stimulation from thalamic or cortical projection neurons), with local inhibitory neurons (green), leading to a stereotyped excitatory-inhibitory sequence of post-synaptic potentials, which increases the temporal precision of depolarization and enhances phasic activity of the pyramidal neuron network. The identification of molecular alterations in these circuits is providing critical insights for the rational development of new therapeutic interventions.Lewis DA and Sweet RA: Schizophrenia from a neural circuitry perspective: advancing towards rational pharmacological therapies. J Clin Investigation, in press.
Many human brain diseases are associated with disturbances in the structure and function of cortical synapses. Answering fundamental questions about the synaptic machinery in these disease states requires the ability to image and quantify small synaptic structures in tissue sections and to evaluate protein levels at these major sites of function. We developed a new automated segmentation imaging method specifically to answer such fundamental questions. The method takes advantage of advances in spinning disk confocal microscopy, and combines information from multiple iterations of a fluorescence intensity/morphological segmentation protocol to construct three-dimensional object masks of immunoreactive (IR) puncta. This new methodology is unique in that high- and low-fluorescing IR puncta are equally masked, allowing for quantification of the number of fluorescently-labeled puncta in tissue sections (panel). In addition, the shape of the final object masks highly represents their corresponding original data. Thus, the object masks can be used to extract information about the IR puncta (e.g., average fluorescence intensity of proteins of interest). Importantly, the segmentation method presented can be easily adapted for use with most existing microscopy analysis packages.Fish KN, Sweet RA, Deo AJ, Lewis DA: An automated segmentation methodology for quantifying immunoreactive puncta number and fluorescence intensity in tissue sections. Brain Res, 1240: 62-72, 2008.
Accumulating evidence indicates that synchronization of cortical neuronal activity at gamma-band frequencies is important for various types of perceptual and cognitive processes. Experimental models as well as preclinical studies suggest that GABA-A receptor-mediated transmission is required for the induction of network oscillations. However, to date, there is no evidence linking GABA transmission with gamma-band oscillations in humans. Using a novel positron emission tomography (PET) brain-imaging paradigm, we measured the in vivo binding of the benzodiazepine (BDZ) site specific radiotracer [11C]flumazenil at baseline and in the context of elevated GABA levels induced via blockade of the GABA membrane transporter (GAT1) with tiagabine. Preclinical work suggests that increased GABA levels enhance the affinity of GABA-A receptors for BDZ ligands via a conformational change (termed the ‘GABA-shift’). Theoretically, such an increase in affinity of GABA-A receptors should be detected as an increase in the binding of a GABA-A BDZ-receptor site-specific PET radioligand. In fact, we observed significant increases post-GAT1 blockade in [11C]flumazenil binding over baseline values across all cortical brain regions. This is illustrated in Panel A, showing MRI (top) and coregistered parametric BPND (unitless) maps measured under baseline (middle) and 30 minutes post-tiagabine (bottom) following [11C]flumazenil injection in a healthy female volunteer. Moreover, the ability to increase GABA levels, measured as the change in [11C]flumazenil binding potential, strongly predicted the ability to entrain cortical networks, measured via EEG gamma synchrony in these same subjects (Panel B). These data provide preliminary evidence of the ability to measure acute fluctuations in extracellular GABA levels with PET and provide the first in vivo documentation of the relationship between GABA neurotransmission and gamma-band power in humans.Frankle WG, Cho RY, Narendran R, Mason NS, Vora S, Litschge M, Price JC, Lewis DA, Mathis CA: Tiagabine increases [11C]flumazenil binding in cortical brain regions in healthy control subjects. Neuropsychopharmacology, ePub July 9, 2008.
The Cameos of Caring Program, which includes 55 area healthcare facilities and schools of nursing, recognizes nursing professionals who demonstrate excellence in nursing care, serve as advocates for patients and families, and embody the essence of the nursing profession. This year Kevin Eklund, BSN, was among those recognized for this prestigious award. Kevin serves as project coordinator of the Services for the Treatment of Early Psychoses (STEP) research program at Western Psychiatric Institute and Clinic, and he plays a central role in subject recruitment and diagnostic evaluation for the Clinical Services and Diagnostics Core of the CCNMD. Kevin was selected for the Cameos of Caring award for his consistent excellence and compassion in both clinical care and research. Head nurse in the Diagnostic Evaluation Center, Jennifer Lynn Schneeman says, “Patients and families testify that Kevin’s skills have provided them hope at the commencement and continuum of the recovery process. He is an image and inspiration for staff, patients, and families.” Dr. David Lewis, Director of the CCNMD, has noted that Kevin is “particularly skilled at helping individuals with schizophrenia understand whether a given research project will be a good experience for them, and in supporting them through the process with extraordinary energy and genuine compassion.” CONGRATULATIONS, KEVIN!
25th Annual Schizophrenia Conference
November 21, 2008
Sheraton Station Square Hotel, Pittsburgh, PA
The Pittsburgh Schizophrenia Conference is an annual meeting at which the latest advances in schizophrenia research are reviewed by leading international experts in the field. This year's meeting will cover a diverse range of topics including brain abnormalities and the roles of genes in pathophysiology of schizophrenia. Scientific evidence for the role of cannabis in causing, precipitating, or worsening psychosis will be reviewed. Improving social and vocational function and non-psychiatric medical problems will also be addressed. The family and consumer perspective will also be presented. The presentation of the 2008 Schizophrenia Conference Award and the Gerard E. Hogarty Excellence in Schizophrenia Research Memorial Award will also occur during the meeting.
Who Should Attend
The conference is designed to disseminate the latest research findings to a wide audience: clinicians, researchers, patients and their relatives, and others who wish to keep abreast of etiologic and treatment research in schizophrenia.
Objectives
At the conclusion of the program, participants should be able to:
- Understand the pattern for brain abnormalities commonly associated with schizophrenia.
- Have better understanding of the current knowledge and future directions in research in the genetics of mental illness.
- Understand evidence-based approaches to improving employment outcomes in persons with schizophrenia.
- Understand the increased risk for non-psychiatric medical problems for persons with schizophrenia and proposals for improved integration of mental health and primary care services.
- Understand the ways in which drugs of abuse, like cannabis can induce or precipitate psychotic symptoms and illnesses.
Presented by:
UPMC Health System Western Psychiatric Institute & Clinic;
Schizophrenia Treatment & Research Center;
Mental Health Conference Planning;
University of Pittsburgh School of Medicine;
Center for Continuing Education in the Health Sciences
Individuals with schizophrenia exhibit disturbances in a number of cognitive, affective, sensory and motor functions that depend on the circuitry of different cortical areas. The cognitive deficits associated with dysfunction of the dorsolateral prefrontal cortex (DLPFC) result, at least in part, from abnormalities in GABA neurotransmission as reflected in a specific pattern of altered expression of GABA-related genes. Consequently, in this study we sought to determine whether this pattern of altered gene expression is restricted to the DLPFC or could also contribute to the dysfunction of other cortical areas in the illness. Real-time quantitative polymerase chain reaction was used to assess the levels of eight GABA-related transcripts in four cortical areas (DLPFC, anterior cingulate, primary motor and primary visual cortices) from 12 subjects with schizophrenia and matched normal comparison subjects. Expression levels of seven transcripts were lower in the subjects with schizophrenia with the magnitude of the reductions for each transcript indistinguishable across the four areas (Figure). The largest reductions were detected for the mRNAs encoding somatostatin (SST) and parvalbumin (PV), followed by moderate decreases in mRNA expression for the 67 kD isoform of glutamate decarboxylase (GAD67), the GABA membrane transporter 1 (GAT1), and the α1 and δ subunits of GABAA receptors. In contrast, the expression of calretinin (CR) mRNA did not differ between the subject groups in any of the four areas. Because the areas examined represent the major functional domains (e.g., association, limbic, motor and sensory) of the cerebral cortex, our findings suggest that a conserved set of molecular alterations affecting GABA neurotransmission contributes to the pathophysiology of different clinical features of schizophrenia.Takanori Hashimoto, H Holly Bazmi, Karoly Mirnics, Qiang Wu, Allan R Sampson, and David A Lewis: Conserved Regional Patterns of GABA-Related Transcript Expression in the Neocortex of Subjects with Schizophrenia. Am J Psychiatry, 165:479-489, 2008.
Translational Neuroscience Program Seminar Series
Date: Mondays
Time: 12:00-1:00 PM
Location: 16th Floor Conference Room (1695 BST) Biomedical Science Tower
Every Monday from 12:00 – 1:00, the Translational Neuroscience Program and the Department of Psychiatry at the University of Pittsburgh sponsor a lunch-hour seminar dedicated to topics in neuroscience and mental health, with a special emphasis on schizophrenia-relevant research. Scientists from inside and outside the University of Pittsburgh present their work to an audience of faculty, staff, residents and students from various departments.
The TNP Seminar Series represents an excellent forum for the communication of novel research ideas and initiatives. The weekly seminars cultivate an atmosphere of cooperation towards translating basic science and research into a better understanding of brain disorders and clinical practice.
For more information about scheduled lectures, please contact
Lisa Murhpree
412-624-3934
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