Lactobacillus johnsonii attenuates chronic stress-induced ovarian dysfunction by modulating ovarian clock-related steroidogenic signaling.

Chronic psychological stress is increasingly implicated in female reproductive disorders, yet the mechanistic link between stress and ovarian dysfunction remains incompletely understood. Using a chronic restraint stress (CRS) mouse model, we demonstrated that CRS induced anxiety-like behaviors and ovarian dysfunction, evidenced by elevated serum FSH levels, reduced estradiol (E2) and anti-Müllerian hormone (AMH) levels, and impaired folliculogenesis. These phenotypes were accompanied by pronounced gut microbiota dysbiosis and disturbed metabolic profiles. Moreover, transplantation of stress-altered microbiota further exacerbated ovarian impairment in recipient mice. Stress-related gut microbiota alterations were associated with changes in ovarian clock gene expression and steroidogenic pathways. Notably, preventive oral supplementation with Lactobacillus johnsonii modulated gut microbial composition, mitigated stress-related behavioral and endocrine abnormalities, and attenuated CRS-induced alterations in ovarian clock protein expression, improved estrogen biosynthesis and follicular development. In conclusion, these findings support a proposed regulatory framework involving stress-associated gut microbiota alterations, ovarian clock gene expression, and steroidogenic dysfunction, and suggest L. johnsonii as a potential preventive microbiota-based intervention for stress-associated ovarian dysfunction.