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Abstract Objectives: This study sought to further verify the protective mechanism of Melatonin (MT) against ovarian damage through animal model experiments and to lay a theoretical and experimental foundation for exploring new approaches for ovarian damage treatment. Method: The wet weight and ovarian index of rat ovaries were weighted, and the morphology of ovarian tissues and the number of follicles in the pathological sections of collected ovarian tissues were recorded. And the serum sex hormone levels, the key proteins of the autophagy pathway (PI3K, AKT, mTOR, LC3II, LC3I, and Agt5) in rat ovarian tissues, as well as the viability and mortality of ovarian granulosa cells in each group were measured by ELISA, western blotting, CCK8 kit and LDH kit, respectively. Results: The results showed that MT increased ovarian weight and improved the ovarian index in ovarian damage rats. Also, MT could improve autophagy-induced ovarian tissue injury, increase the number of primordial follicles, primary follicles, and sinus follicles, and decrease the number of atretic follicles. Furthermore, MT upregulated serum AMH, INH-B, and E2 levels downregulated serum FSH and LH levels in ovarian damage rats and activated the PI3K/AKT/mTOR signaling pathway. Besides, MT inhibited autophagic apoptosis of ovarian granulosa cells and repressed the expression of key proteins in the autophagic pathway and reduced the expression levels of Agt5 and LC3II/I. Conclusions: MT inhibits granulosa cell autophagy by activating the PI3K/Akt/mTOR signaling pathway, thereby exerting a protective effect against ovarian damage.
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OBJECTIVE: The degree of destruction of primordial follicles was investigated following the administration of cyclophosphamide or paclitaxel respectively in mouse ovaies. And then the effect of GnRHa I, GnRH antagonist and GnRHa II on the primordial follicles was evaluated following the administration of cyclophosphamide or paclitaxel. METHODS: Saline or cyclophosphamide (50 mg/kg or 75 mg/kg) were intraperitoneally injected into seven-week old female ICR mice. GnRHa I (Leuplin(R)), GnRH antagonist (Cetrotide(R)) or GnRHa II (H-6038) was injected into mice, and administered with 50 mg/kg and 75 mg/kg of cyclophosphamide following 9 days treatment with GnRH analogues. After collecting ovaries, H&E staining was performed and the number of primordial follicles was counted. To confirm the induction of apoptosis, TUNEL assay was performed. Another experimental groups of mice were administered with a low concentration (12.5 mg/kg) or a high concentraion (19 mg/kg) of paclitaxel. RESULTS: Cyclophosphamide and paclitaxel cause mild to moderate destruction of primordial follicles in mouse ovaries. The number of primordial follicles in the group of high dose was noted less than in that of low dose treated with cyclophosphamide or paclitaxel. Increased the apoptotic indices were shown in the group of cyclophosphamide or paclitaxel compared to in saline only treated group. Treatment with GnRHa I, GnRH antagonist and GnRHa II significantly increased the number of primordial follicles at a low concentration of cytotoxic agents (P<0.05), whereas the number of primoridal follicle increased only in GnRHa I antagonist treated group at a high concentration of cyclophosphamide or paclitaxel (P<0.05). CONCLUSION: The present study shows that GnRH analogues alleviate destruction of primordial follicles caused by cyclophosphamide and paclitaxel in mouse ovaries, suggesting that GnRH analogues may be applicable to increase fertility opportunity in malignant cancer patients of reproductive age planning future pregnancies.