Medial prefrontal cortical CB1Rs and astrocytes are involved in depression and the antidepressant effects of running exercise in male rats.

Abstract

Depression represents a growing global health challenge, with current pharmacological treatments often exhibiting limited efficacy and significant side effects. Although physical exercise, particularly running exercise, has shown promising antidepressant properties, its underlying neurobiological mechanisms remain poorly understood. In this study, we investigated whether cannabinoid receptor type 1 (CB1R) in the medial prefrontal cortex (mPFC) contributed to the therapeutic benefits of running exercise, which might be associated with astrocyte-related changes. Using a chronic restraint stress (CRS) male rat model of depression, we integrated behavioral assessments (saccharin preference and forced swim tests) with multimodal molecular and cellular analyses, including immunohistochemistry, stereology, immunofluorescence, RT-PCR, and Western blotting. Our findings demonstrate that running exercise alleviated depressive-like behaviors, restored mPFC CB1R expression, and reversed stress-induced reductions in GFAP-positive cells. Conversely, mPFC-specific CB1R knockdown induced depressive-like phenotypes and astrocytic alterations, while CB1R overexpression reproduced some benefits of running exercise. Notably, running exercise failed to improve behavior or astrocytic changes when mPFC CB1R was knocked down, supporting a necessary role for intact mPFC CB1R signaling. These results suggested that mPFC CB1R contributes to running exercise-induced antidepressant effects, and this process is closely associated with the regulation of astrocytic states, providing a potential molecular framework for future therapeutic strategies.