Melatonin protects ovarian function in whole cryopreserved rat ovarian transplantation via the MT1/Nrf2/ARE pathway

Abstract

Background: Whole ovarian transplantation has the potential to restore fertility in cancer patients, but ovarian ischemia-reperfusion injury following transplantation causes decreased graft function. Melatonin protects against antioxidant damage and has anti-inflammatory effects, but its effects in whole ovarian transplantation have not been investigated. Objective:This study was aimed to verify the beneficial antioxidant and anti-inflammatory effects of melatonin in whole ovarian transplantation. Methods: The cryopreserved whole ovaries were allotransplanted in LEWIS rats. Forty rats were randomly divided into 8 groups: control group, sham surgery group, saline group; low-dose (25 mg/kg) melatonin group; high-dose (50 mg/kg) melatonin group; melatonin (50 mg/kg) + ML385 group; melatonin (50 mg/kg) + luzindole group, and melatonin+ 4P-PDOT group. The estrous cycle recovery was evaluated by vaginal exfoliative cell monitoring and serum hormone. Follicle morphology was observed by HE. The levels of eoxidative stress factors, antioxidant factors, and inflammatory factors in both serum and ovarian tissues were measured by ELISA, RT-qPCR, western blot and fenton detection. RT-qPCR, western blot and immunofluorescence assays were used to measure the levels of MT1 and Nrf2. Results: The rats in high-dose and low-dose melatonin groups recovered estrous cycle faster and lost fewer follicles, and the serum endocrine hormone levels were close to normal. The serum and ovarian tissue antioxidant capacity were significant higher, while the levels of inflammatory factors were significant lower in the high-dose and low-dose melatonin groups. In addition, the melatonin receptor MT1 was found to be involved in antioxidant and anti-inflammatory processes. Melatonin also triggered the Nrf2/ARE pathway activity via receptor MT1. Blocking Nrf2 or MT1 receptors could eliminate the beneficial effects of melatonin on whole transplanted ovaries. These findings suggest that melatonin can attenuate oxidative stress injury and inflammatory responses in whole transplanted ovaries via the MT1/Nrf2/ARE signaling pathway, thereby effectively protecting whole transplanted ovarian function.