Pterostilbene attenuates VCD-induced ovarian damage through modulation of oxidative stress, inflammation, apoptosis, and SIRT1/FOXO3a gene expression

Background : Primary ovarian insufficiency (POI) is characterized by depletion of ovarian follicles and impaired ovarian function. Oxidative stress, inflammation, and dysregulation of intracellular signaling pathways play important roles in POI progression. Pterostilbene (PTS) is a natural stilbene compound with potent antioxidant and anti-inflammatory properties, demonstrating protective effects in several experimental models. The present study investigated the effects of PTS on oxidative stress and inflammation, as well as sirtuin 1 (SIRT1) and forkhead box O3a (FOXO3a) gene expression in a rat model of 4-vinylcyclohexene diepoxide (VCD)-induced POI. Methods : Female Sprague-Dawley rats were randomly divided into five experimental groups (six animals per group). Intraperitoneal (i.p.) administration of VCD (160 mg/kg) was used to induce POI. The rats were then treated with 17β-estradiol, PTS (50 mg/kg) orally by gavage, or their combination according to the study design, while the control group received the appropriate vehicle only. The serum levels of total antioxidant capacity (T-AOC) and nuclear factor-kappa B (NF-κB) were determined using an enzyme-linked immunosorbent assay (ELISA). Ovarian expression of SIRT1 and FOXO3a was assessed by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Immunohistochemical (IHC) staining for cleaved caspase-3 (CASP3) and 8-hydroxy-2 ' -deoxyguanosine (8-OHdG) was used to evaluate apoptosis and oxidative deoxyribonucleic acid (DNA) damage in ovarian tissue, respectively. The combination effect was assessed using the Bliss equation. Results : Treatment with PTS significantly reduced NF-κB ( P = 0.0496) and upregulated SIRT1 and FOXO3a gene expression ( P = 0.0001), with maximum fold changes of 11.04 and 8.83, respectively. It also significantly reduced CASP3 and 8-OHdG ( P = 0.0001), whereas the increase in T-AOC did not reach statistical significance ( P = 0.3260). Overall, compared with 17β-estradiol, treatment with PTS produced greater effects on SIRT1 and FOXO3a gene expression. The combination treatment showed synergistic or near-additive effects for several evaluated parameters, whereas antagonistic interactions were observed for SIRT1 and FOXO3a gene expression. Combination index values for all measured parameters were as follows: T-AOC, 0.942; NF-κB, 0.690; SIRT1, 11.688; FOXO3a, 11.942; CASP3 percentage score (P-score), 1.0; CASP3 immunoreactive score (IRS), 0.997; 8-OHdG P-score, 0.943; and 8-OHdGIRS, 0.962. Conclusion : Treatment with PTS attenuated VCD-induced ovarian injury through antioxidant and anti-inflammatory mechanisms, with modulation of SIRT1/FOXO3a gene expression and reduced NF-κB-mediated inflammation and CASP3-associated apoptosis.