Synergistic modulation of insulin resistance and ovarian oxidative stress by alpha-lipoic acid and vitamin D in an experimental rat model of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is characterized by insulin resistance, hyperandrogenism, oxidative stress, and disrupted folliculogenesis. The present study aimed to investigate whether combined alpha-lipoic acid (ALA) and vitamin D therapy exerts synergistic effects on metabolic, oxidative, endocrine, and histomorphological parameters in a letrozole-induced rat model of PCOS. Sixty female Wistar Albino rats were randomly divided into six groups: Control, PCOS, PCOS+Metformin (500 mg/kg/day), PCOS+Vitamin D (1000 IU/kg/day), PCOS + ALA (100 mg/kg/day), and PCOS + ALA+Vitamin D. PCOS was induced with letrozole (1 mg/kg/day) for 21 days, followed by 30 days of treatment. Fasting blood glucose (FBG), insulin, and HOMA-IR were assessed to evaluate metabolic status. Ovarian oxidative stress markers (MDA, SOD, CAT, GSH), serum hormonal parameters (testosterone, LH, FSH, LH/FSH ratio), and detailed histomorphometric analyses were performed. Statistical analyses included one-way and two-way ANOVA. Letrozole administration induced persistent diestrus, hyperandrogenemia, increased ovarian weight, elevated HOMA-IR (6.61 ± 1.18 vs. 2.24 ± 0.42, p < 0.001), and marked oxidative stress (MDA: 5.84 ± 0.72 vs. 2.31 ± 0.34 nmol/mg, p < 0.001). ALA and vitamin D monotherapies significantly improved metabolic, oxidative, and endocrine parameters compared with untreated PCOS rats (p < 0.05). The combination therapy group demonstrated the most pronounced improvements, with HOMA-IR (2.43 ± 0.47), MDA (2.52 ± 0.39 nmol/mg), testosterone (1.29 ± 0.27 ng/mL), and LH/FSH ratio (1.03 ± 0.19) values approaching control levels (all p < 0.01 vs. PCOS). Histologically, combined treatment markedly reduced cystic follicles and restored granulosa and theca thickness. Two-way ANOVA revealed significant interaction effects for HOMA-IR, MDA, testosterone, and LH/FSH ratio (p < 0.05). Combined ALA and vitamin D therapy produced enhanced improvements in insulin resistance, oxidative stress, endocrine imbalance, and ovarian morphology in experimental PCOS. Simultaneous targeting of mitochondrial redox dysfunction and endocrine-metabolic signaling pathways may represent a promising multidimensional therapeutic approach in PCOS.