Antioxidant Protective Effect of Melatonin on Cyclophosphamide-Induced Premature Ovarian Failure and its Mechanism

Objective: To study the antioxidant protective effect and mechanism of melatonin on cyclophosphamide-induced premature ovarian failure model mice. Methods: Six-month sexually mature female Kunming mice were taken for one week of acclimatization and then randomly divided into a normal group, blank control group, drug control group, ovarian premature aging model group, and melatonin intervention low, medium, and high dose group, with 20 mice in each group. We observed the status and body mass of the mice in each group; observed and monitored the estrous cycle by HE staining; measured the diameter and size of the ovaries and weighed the wet weight of the ovaries; observed the morphological changes of the ovaries by HE staining and counted the developing follicles at all levels; detected the levels of serum estradiol (E2), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) by ELISA; measured the levels of serum MDA, SOD, and GSH-PX by antioxidant kit; detected the levels of protein immunoblotting by ELISA; protein immunoblotting (Western blot) to examine the expression of DNA damage-related proteins γH2AX, p53, and p21 in ovarian tissues. Results: Compared with the control group, mice in the premature ovarian failure model group showed reduced mobility, rough hair, decreased body weight, disorganized estrous cycle, decreased ovarian weight (P < 0.05), decreased number of follicles at all levels of development (P < 0.05), increased number of atretic follicles (P < 0.05), significantly elevated levels of serum FSH and LH, significantly decreased levels of E2 (P < 0.05), significantly increased levels of serum MDA, significantly lower SOD and GSH-PX levels (P < 0.05), and the expression of p53, p21, and γH2AX in ovarian tissues was increased (P < 0.05). Compared with the model group of premature ovarian failure, melatonin improved the changes of the above indexes induced by cyclophosphamide-induced premature ovarian failure in mice. Conclusion: Melatonin can improve the changes of motility cycle disorders, abnormal follicular development, and abnormal serum hormone levels induced by cyclophosphamide-induced oxidative stress in mice with premature ovarian failure. At the same time, melatonin can improve the oxidative stress induced by cyclophosphamide and alleviate the role of oxidative stress-induced DNA damage in mouse ovaries by exerting its antioxidant effect.