Circadian rhythm disruption induces PCOS-like phenotypes by interfering with ovarian steroid hormone synthesis pathways.

Stressors are a critical contributor to reproductive dysfunction. This study investigated whether experimentally induced chronic stress leads to infertility and elucidated its disruptive mechanisms on the female reproductive endocrine system. Three chronic stress models were established in female ICR mice: chronic restraint stress (CRS), circadian rhythm disruption (CR), and chronic unpredictable mild stress (CUMS). Systemic evaluations revealed that the CR model most significantly activated the hypothalamic-pituitary-adrenal (HPA) axis, as indicated by elevated corticosterone and epinephrine levels. Macro- and micro-level quantitative analyses demonstrated that CR treatment significantly reduced body weight, ovarian and uterine coefficients, increased atretic follicles, disrupted estrous cycles, and decreased litter size. Hormonal assays showed decreased levels of luteinizing hormone (LH), progesterone, estradiol, and melatonin, while testosterone levels were elevated. This pattern of alterations closely resembled the endocrine profile of polycystic ovary syndrome (PCOS). Further ovarian transcriptome analysis identified 538 differentially expressed genes. Key estrogen synthesis genes (Star, Cyp19a1, Cyp17a1, 3β-Hsd, 17β-Hsd) and rate-limiting enzymes were significantly downregulated. Notably, expression of luteinizing hormone receptor (Lhr) showed compensatory upregulation, suggesting a feedback response to impaired steroidogenesis. Functional enrichment analysis highlighted significant alterations in steroid hormone synthesis, cAMP signaling, and metabolic pathways. Our findings suggest that circadian rhythm disruption impairs reproductive function primarily through downregulating key genes in the estrogen synthesis pathway. This work confirms the induction of a PCOS-like phenotype by artificial stress and reveals novel mechanistic insights, thereby identifying potential therapeutic targets for stress-associated PCOS.