Puerarin restores testicular steroidogenesis via VDR-cyclic AMP/PKA signaling in a chronic unpredictable stress (CUS) rat model.

Chronic psychological stress is a well-established factor contributing to male infertility by disrupting testicular function through oxidative stress, inflammation, and hormonal imbalance. This study aimed to investigate the protective effects of puerarin, a natural isoflavonoid, on chronic unpredictable stress (CUS)-induced testicular damage, with a specific focus on the vitamin D receptor (VDR)-mediated cyclic AMP/PKA signaling pathway. Adult male rats were divided into four groups (n = 6/group): Control, CUS, CUS + Puerarin (80 mg/kg; T1), and CUS + Puerarin (120 mg/kg; T2). CUS was given for 8 weeks, and puerarin was administered intraperitoneally during the final 4 weeks. Molecular docking was used to evaluate puerarin's binding affinity to VDR. Biochemical, molecular, histological, and ultrastructural analyses were performed to assess testicular function. CUS significantly reduced testicular VDR expression, cyclic AMP levels, PKA activity, and the expression of steroidogenic proteins (StAR and 17β-HSD3), while increasing IL-6, TNF-α, and oxidative stress markers. Puerarin treatment restored VDR expression, enhanced cyclic AMP levels, improved steroidogenic protein expression, and partially restored PKA activity. Sperm quality and testicular histoarchitecture were also markedly improved. This is the first study to demonstrate that puerarin alleviates stress-induced testicular dysfunction via the VDR-cyclic AMP/PKA signaling pathway. These findings position puerarin as a promising, multi-target, and affordable therapeutic option for managing stress-related male reproductive impairments.