|Altered Parvalbumin Basket Cell Inputs in the Dorsolateral Prefrontal Cortex of Schizophrenia Subjects
Cortical circuitry dysfunction in schizophrenia has been studied at many different levels of resolution, but not at the most basic unit of network organization—synaptic inputs. Multi-label electron or confocal light microscopy is required to examine specific types of synaptic inputs, and application of these methods to quantitatively study disease-related changes in human postmortem tissue has not been feasible for technical reasons. We recently developed a multi-label confocal light microscopic approach that makes possible the systematic identification and quantification of synaptic inputs, and of the relative levels of proteins localized to these inputs, in human postmortem tissue. We applied this approach to quantify parvalbumin basket cell (PVBC) inputs in area 9 of the dorsolateral prefrontal cortex from schizophrenia and matched comparison subjects. Tissue sections were triple-labeled for the 65 kD isoform of glutamic acid decarboxylase (GAD65), PV and the GABAA receptor α1 subunit (figure). PVBC axonal boutons were defined as PV/GAD65 dual-labeled puncta, and PVBC inputs were defined as a PVBC bouton that overlapped a GABAA receptor α1 subunit punctum. The density of PVBC inputs was unchanged in subjects with schizophrenia, but levels of PV protein were lower in PVBC boutons. In concert with prior reports, these findings indicate that PVBC dysfunction in schizophrenia reflects molecular and not structural alterations in these cells and their axon terminals.
|Four channel imaging experimental design. Sections containing human dorsolateral prefrontal cortex (DLPFC) area 9 were imaged for (a) GABAA α1 subunit (488 channel), (b) glutamic acid decarboxylase 65 (GAD65; 647 channel), (c) parvalbumin (PV; 568 channel) and (d) lipofuscin autofluorescence, which is visible in all channels (405 channel). (e) Mask of the lipofuscin signal. (f) Merged image of remaining immunolabel used for analysis after lipofuscin subtraction. (g–i) 3X zoom of the boxed region showing fluorescent signal in the 488, 647 and 568 channels, respectively. (g'–i') 3X zoom of the boxed region showing fluorescent signal in the 488, 647 and 568 channels, respectively, after lipofuscin autofluorescence subtraction. Filled arrowhead indicates a triple-immunolabeled parvalbumin basket cell (PVBC) input included in final analysis. Filled arrow indicates a false-positive PVBC input (g–i merge) eliminated after lipofuscin autofluorescence subtraction (g'–i' merge). Scale bar: 5 µm. PC, pyramidal cell.|
|Glausier JR, Fish KN and Lewis DA: Altered Parvalbumin Basket Cell Inputs in the Dorsolateral Prefrontal Cortex of Schizophrenia Subjects. Molecular Psychiatry 19: 30–36, 2014.|