Psilocybin restores behavioral and neuroplastic deficits induced by chronic stress in rats.
Agnieszka Bysiek, Izabela Szpręgiel, Adam Wojtas, Marzena Maćkowiak, Agnieszka Wawrzczak-Bargieła, Monika Leśkiewicz, Ewa Trojan, Katarzyna Kamińska, Weronika Kumorek, Wiktor Bilecki, Krystyna Gołembiowska
Progress in neuro-psychopharmacology & biological psychiatry June 20, 2026 DOI: 10.1016/j.pnpbp.2026.111710 via PubMed
Summary
AI-generated from the abstractTwo doses of psilocybin (0.6 mg/kg, given subcutaneously seven days apart) reversed anhedonia, produced antidepressant-like effects in the forced swim test, and reduced anxiety in the light/dark box, elevated plus maze, and open field tests in rats exposed to chronic unpredictable mild stress. Psilocybin also increased hippocampal neurogenesis, shown by higher numbers of BrdU-positive, DCX-positive, and Ki-67-positive cells in stressed animals. Stress-induced reductions in brain-derived neurotrophic factor (BDNF) expression appeared linked to normalization of hypothalamic-pituitary-adrenal (HPA) axis activity. The findings highlight psilocybin-induced neuroplasticity as a key mechanism for its antidepressant and anxiolytic effects.
Study at a glance
| Characteristics | Experimental study Peer reviewed |
|---|---|
| Population | Stressed rats |
| Intervention | Psilocybin |
| Dose | 0.6 mg/kg, s.c., 7 days apart |
| Topics | Neuroplasticity Psilocybin |
| Keywords | Behavior |
| Key finding | Psilocybin reversed anhedonia, produced antidepressant and anxiolytic effects, and induced hippocampal neurogenesis in stressed rats. |
Abstract
Psychedelics have emerged as a promising novel therapeutic approach for major depressive disorder (MDD). Altered activity and structural atrophy of the prefrontal cortex, hippocampus, and limbic structures are associated with depressive disorders. Psilocybin may reverse the loss of synaptic connections and restore the function of these brain regions. In this study, we investigated the effects of psilocybin on rat behavior, hippocampal neurogenesis, expression level of brain-derived neurotrophic factor (BDNF) and hypothalamic-pituitary-adrenal (HPA) axis activity. Psilocybin administered in two doses (0.6 mg/kg, s.c., 7 days apart) reversed anhedonia in stressed rats, produced antidepressant-like effects in the forced swim test (FST), and exerted anxiolytic activity in the light/dark box (LDB), elevated plus maze (EPM), and open field (OF) tests in stressed animals. Psilocybin induced hippocampal neurogenesis as evidenced by increasing the number of BrdU-positive cells (an exogenous marker of cell proliferation and survival), DCX-positive cells (a marker of immature neurons), and Ki-67-positive cells (an endogenous marker of cell proliferation) in stressed animals. Stress-induced reductions in BDNF expression levels appeared to be associated with normalization of HPA axis activity. These findings underscore the role of psilocybin-induced neuroplasticity in the antidepressant and anxiolytic mechanisms of psychedelics.