title: Chronic stress reduces the number of GABAergic interneurons in the adult rat hippocampus, dorsal-ventral and region-specific differences.
abstract: Major depressive disorder is a common and complex mental disorder with unknown etiology. GABAergic dysfunction is likely to contribute to the pathophysiology since disrupted GABAergic systems are well documented in depressed patients. Here we studied structural changes in the hippocampal GABAergic network using the chronic mild stress (CMS) model, as one of the best validated animal models for depression. Rats were subjected to 9 weeks of daily stress and behaviorally characterized using the sucrose consumption test into anhedonic and resilient animals based on their response to stress. Different subtypes of GABAergic interneurons were visualized by immunohistochemistry using antibodies for parvalbumin (PV), calretinin (CR), calbindin (CB), cholecystokinin (CCK), somatostatin (SOM), and neuropeptide Y (NPY). We used an unbiased quantification method to systematically count labeled cells in different subareas of the dorsal and ventral hippocampus. Chronic stress reduced the number of specific interneurons in distinct hippocampal subregions significantly. PV+ and CR+ neurons were reduced in all dorsal subareas, whereas in the ventral part only the CA1 was affected. Stress had the most pronounced effect on the NPY+ and SOM+ cells and reduced their number in almost all dorsal and ventral subareas. Stress had no effect on the CCK+ and CB+ interneurons. In most cases the effect of stress was irrespective to the behavioral phenotype. However, in a few specific areas the number of SOM+, NPY+, and CR+ neurons were significantly reduced in anhedonic animals compared to the resilient group. Overall, these data clearly demonstrate that chronic stress affects the structural integrity of specific GABAergic neuronal subpopulations and this should also affect the functioning of these hippocampal GABAergic networks.
authors.affiliation: Institute of Laboratory Medicine, Faculty of Medicine, University of Pécs, 7624, Pécs, Hungary; Structural Neurobiology Research Group, Szentágothai János Research Center, University of Pécs, 7624, Pécs, Hungary; Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, 8240, Risskov, Denmark.
authors.forename: Boldizsár
authors.initials: B
authors.lastname: Czéh
authors.forename: Zsófia K Kalangyáné
authors.initials: ZK
authors.lastname: Varga
authors.forename: Kim
authors.initials: K
authors.lastname: Henningsen
authors.forename: Gábor L
authors.initials: GL
authors.lastname: Kovács
authors.forename: Attila
authors.initials: A
authors.lastname: Miseta
authors.forename: Ove
authors.initials: O
authors.lastname: Wiborg
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D064092:Calbindin 1 / Q000378:metabolism; D002452:Cell Count; D002766:Cholecystokinin / Q000378:metabolism; D004195:Disease Models, Animal; D005518:Food Preferences; D059330:GABAergic Neurons / Q000378:metabolism / Q000473:pathology*; D006624:Hippocampus / Q000473:pathology*; D007395:Interneurons / Q000378:metabolism / Q000473:pathology*; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013315:Stress, Psychological / Q000473:pathology*; D013395:Sucrose / Q000008:administration & dosage; D013549:Sweetening Agents / Q000008:administration & dosage
chemical_list: D064092:Calbindin 1; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D013549:Sweetening Agents; C410885:cholecystokinin 8; D013395:Sucrose; D002766:Cholecystokinin
keywords: CMS; calretinin; dorsoventral; neuropeptide Y; parvalbumin; somatostatin