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Updated: Jul 14, 2026
The Unpredictable Chronic Mild Stress Protocol for Inducing Anhedonia in Mice
Published on: October 24, 2018
Intestinal γδ T17-IL-17A signaling disrupts hippocampal mitophagy in stress-induced depression and is restored by
Mengqi Han1,2, Bing Xie1,2, Yuan Yu1,2
1Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
Abstract:
Chronic stress precipitates depression, yet how gut-immune-brain interactions translate stress into mood pathology remains unclear. We tested the hypothesis that stress-primed small intestinal γδ T cells drive hippocampal mitochondrial dysfunction and depression-like behavior via interleukin-17A (IL-1A). In mice exposed to chronic restraint stress (CRS), we combined behavioral assays (open-field, sucrose-preference, tail-suspension, forced-swim), 16S rRNA profiling, fecal microbiota transplantation, Kaede photoconversion, conditional CD8α deletion in γδ T cells, hippocampal IL-17A overexpression, rapamycin treatment, and administration of the antidepressant arketamine. CRS increased gut and brain permeability, induced gut-microbiota dysbiosis, and promoted migration of small intestinal CD8α⁺ γδ T17 cells to the meninges and brain; γδ T cells were the predominant IL-17A source in the brain. Kaede tracing confirmed an intestinal origin, and CRS-associated microbiota alone transferred γδ T cell trafficking and depression-like behavior to recipients. In the hippocampus, CRS elevated IL-17A and impaired PINK1/Parkin-mediated mitophagy (decreased PINK1, Parkin, Beclin-1, and LC3B-II/I; increased p62), reduced ATP, and produced mitochondrial and synaptic ultrastructural deficits. IL-17A overexpression further worsened mitophagy and behavior, whereas rapamycin restored both. Conditional deletion of CD8α in γδ T cells reduced brain γδ T17 infiltration, lowered hippocampal IL-17A, rescued mitophagy and synapses, and improved behavior. Arketamine normalized dysbiosis and barrier markers, curtailed γδ T cell trafficking, decreased hippocampal IL-17A, restored mitophagy, and alleviated depression-like behavior in both sexes. These findings delineate a stress-responsive microbiota-γδ T cell-IL-17A pathway that compromises hippocampal mitophagy and identify arketamine as a candidate modulator of this axis, nominating mitophagy and γδ T cell trafficking as translational targets.
