title: Pathological Basis for Deficient Excitatory Drive to Cortical Parvalbumin Interneurons in Schizophrenia.
abstract: OBJECTIVE
  Deficient excitatory drive to parvalbumin-containing cortical interneurons is proposed as a key neural substrate for altered gamma oscillations and cognitive dysfunction in schizophrenia. However, a pathological entity producing such a deficit has not been identified. The authors tested the hypothesis that cortical parvalbumin interneurons receive fewer excitatory synaptic inputs in individuals with schizophrenia.
  
  
  METHODS
  Fluorescent immunohistochemistry, confocal microscopy, and post-image processing techniques were used to quantify the number of putative excitatory synapses (i.e., the overlap of vesicular glutamate transporter 1-positive [VGlut1+] puncta and postsynaptic density protein 95-positive [PSD95+] puncta) per surface area of parvalbumin-positive (PV+) or calretinin-positive (CR+) neurons in the dorsolateral prefrontal cortex from schizophrenia subjects and matched unaffected comparison subjects.
  
  
  RESULTS
  Mean density of VGlut1+/PSD95+ puncta on PV+ neurons was 18% lower in schizophrenia, a significant difference. This deficit was not influenced by methodological confounds or schizophrenia-associated comorbid factors, not present in monkeys chronically exposed to antipsychotic medications, and not present in CR+ neurons. Mean density of VGlut1+/PSD95+ puncta on PV+ neurons predicted the activity-dependent expression levels of parvalbumin and glutamic acid decarboxylase 67 (GAD67) in schizophrenia subjects but not comparison subjects.
  
  
  CONCLUSIONS
  To the authors' knowledge, this is the first demonstration that excitatory synapse density is lower selectively on parvalbumin interneurons in schizophrenia and predicts the activity-dependent down-regulation of parvalbumin and GAD67. Because the activity of parvalbumin interneurons is required for generation of cortical gamma oscillations and working memory function, these findings reveal a novel pathological substrate for cortical dysfunction and cognitive deficits in schizophrenia.
authors.affiliation: From the Translational Neuroscience Program, Department of Psychiatry, and the Medical Scientist Training Program, University of Pittsburgh School of Medicine, Pittsburgh.
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Chung
authors.affiliation: From the Translational Neuroscience Program, Department of Psychiatry, and the Medical Scientist Training Program, University of Pittsburgh School of Medicine, Pittsburgh.
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Fish
authors.affiliation: From the Translational Neuroscience Program, Department of Psychiatry, and the Medical Scientist Training Program, University of Pittsburgh School of Medicine, Pittsburgh.
authors.forename: David A
authors.initials: DA
authors.lastname: Lewis
mesh_terms: D000328:Adult; D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology; D064032:Calbindin 2 / Q000378:metabolism; D016022:Case-Control Studies; D000076122:Disks Large Homolog 4 Protein; D005260:Female; D005968:Glutamate Decarboxylase / Q000096:biosynthesis; D006801:Humans; D007395:Interneurons / Q000187:drug effects / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008252:Macaca fascicularis; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D010320:Parvalbumins / Q000187:drug effects / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000378:metabolism* / Q000473:pathology*; D012559:Schizophrenia / Q000378:metabolism* / Q000473:pathology*; D050598:Vesicular Glutamate Transport Protein 1 / Q000378:metabolism
chemical_list: D014150:Antipsychotic Agents; C576764:CALB2 protein, human; D064032:Calbindin 2; C501444:DLG4 protein, human; D000076122:Disks Large Homolog 4 Protein; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D010320:Parvalbumins; C493464:SLC17A7 protein, human; D050598:Vesicular Glutamate Transport Protein 1; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1