Astrocytic plasticity at the dorsal dentate gyrus on an animal model of recurrent depression

are now known to play crucial roles in the central nervous system, supporting and closely interacting with neurons and therefore able to modulate brain function. Both human postmortem studies in brain samples from patients diagnosed with Major Depressive Disorder and from animal models of depression reported numerical and morphological astrocytic changes specifically in the hippocampus. In particular, these studies revealed significant reductions in glial cell density denoted by a decreased number of S100B-positive cells and a decrease in GFAP expression in several brain regions including the hippocampus. To reveal plastic astrocytic changes in the context of recurrent depression, we longitudinally assessed dynamic astrocytic alterations (gene expression, cell densities and morphologic variations) in the hippocampal dentate gyrus under repeated exposure to unpredictable chronic mild stress (uCMS) and upon treatment with two antidepressants, fluoxetine and imipramine. Both antidepressants decreased astrocytic complexity immediately after stress exposure. Moreover, we show that astrocytic alterations, particularly an increased number of S100B-positive cells, are observed after recurrent stress exposure. Interestingly, these alterations were prevented at the long-term by either fluoxetine or imipramine treatment. This article is part of a Special Issue entitled: Lifestyle and Brain Metaplasticity. (c) 2019 IBRO. Published by Elsevier Ltd. All rights reserved.

Automated summary

Astrocytes play crucial roles in the central nervous system, interacting closely with neurons to modulate brain function. Studies have shown numerical and morphological changes in astrocytes in the hippocampus of both Major Depressive Disorder patients and animal models of depression. Antidepressants such as fluoxetine and imipramine can modulate astrocytic alterations, preventing long-term effects of recurrent stress exposure.