Involvement of the PINK1/Parkin signaling pathway in 4-vinylcyclohexene diepoxide-induced ovary toxicity in rats

Exposure to 4-vinylcyclohexene diepoxide (VCD) has been associated to reproductive toxicity, However, the dynamic ovarian function alterations over time in rats and the underlying mechanisms remain unclear. This study investigated the effects of VCD on ovarian function in female Sprague-Dawley (SD) rats on the 25, 60 and 135 days after VCD injection and discovered related mechanisms. Our results showed that VCD had little ovotoxicity on the 25^th day, as no significant changes were observed except for the reduction of preantral follicles. However, on the 60^th day and 135^th day, rats exhibited irregular estrous cycles, abnormal serum sex hormone levels, ovarian morphological damage, decreased primordial and preantral follicles, and increased atretic follicles. We further found that on the 60^th and 135^th day, VCD might exert ovotoxicity by decreasing antioxidant enzyme levels, inhibiting of the Kelch-like ECH-associated protein 1 (KEAP1)/nuclear factor erythroid 2-related factor 2 (NRF2) and PTEN-induced putative kinase 1 (PINK1)/E3 ubiquitin ligase (Parkin) signaling pathway. Interestingly, on the 25^th day, KEAP1/NRF2 and PINK1/Parking signaling pathway were activated. This study provided a wider application in using laboratory rodents as a model of ovarian failure and highlighted that VCD-induced ovotoxicity was linked to the regulation of the KEAP1/NRF2 and PINK1/Parkin signaling pathways.