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Our previous research has shown that melatonin (MLT) can reduce cryopreserved ovarian damage in mice. Yet, the molecular mechanism of MLT protection is still unclear. Some studies have shown that melatonin receptor 1 (MT1) is very important for animal reproductive system. To evaluate whether MLT exerts its protective effect on cryopreserved mice ovarian tissue via MT1, we added antagonist of MT1/MT2 (Luzindor) or antagonist of MT2 (4P-PDOT) to the freezing solution, followed by cryopreservation and thawing of ovarian tissue. The levels of total superoxide dismutase (T-SOD), catalase (CAT), nitric oxide (NO) and malondialdehyde (MDA) were detected. Besides, by using RT-PCR and Western blotting, the expression of Bcl-2, Bax and Nrf2/HO-1 signalling pathway-related proteins was detected. These findings demonstrated that compared with the melatonin group, the addition of Luzindor increased apoptosis, NO and MDA activities, decreased CAT and T-SOD activities and inhibited Nrf2/HO-1 signalling pathway. In conclusion, melatonin can play a protective role in cryopreserved ovarian tissue of mice through MT1 receptor., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Sperm cells can be damaged during the semen cryopreservation process, decreasing their fertilizing ability. Physical damage and oxidative stress may occur during the freeze-thawing process. Antioxidants such as the native antioxidant melatonin can potentially improve cryopreservation outcomes. In this study, we added melatonin to cryoprotectant to examine its effect on frozen-thawed human sperm. We found that adding 0.1mM melatonin to cryoprotectant significantly increased sperm viability (24.80 ± 0.46% vs. 20.97 ± 1.27%, P < 0.05) and membrane integrity (P < 0.05), and decreased intracellular reactive oxygen species and lipid peroxidation damage. Furthermore, mRNA levels of the transcription factor NF-E2-related factor-2 and its downstream genes were significantly increased. Resistance to oxidative stress was enhanced and expression of the antiapoptotic gene Bcl-2 was increased by inclusion of 0.1mM melatonin in the cryoprotectant. Moreover, 0.1mM melatonin upregulated the expression of heat shock protein 90 (HSP90), which confers resistance to stressors in frozen-thawed sperm. Results obtained upon addition of inhibitors of melatonin receptors (luzindole and 4-P-PDOT) and an HSP90 inhibitor (geldanamycin) in the cryoprotectant demonstrated that melatonin promoted HSP90 translation via the melatonin receptor MT1 and increased adenosine triphosphate levels, thus increasing the viability of thawed sperm., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Our previous study revealed that melatonin (MLT) protected the quality of cryopreserved ovarian tissues in mice. This work was carried out to examine the role of MLT in inducing HSP90 expression of ovarian tissue for achieving cryoprotection. Pieces of ovarian tissues were obtained from 50 female rats treated with MLT at 0, 0.001, 0.01, 0.1, and 1 mM, respectively. After cryopreservation-thawing, HSP90 mRNA and protein level were evaluated using qRT-PCR and western blot. The qRT-PCR results revealed that HSP90 mRNA expression was significantly (p < 0.01) upregulated in MLT-treated groups in comparison with the controls (0 mM). Western blot revealed higher HSP90 protein expression in MLT-treated groups compared to control group (0 mM), thus further confirming that MLT positively affected HSP90 expression. Moreover, 0.1 mM MLT had better effects than other concentrations of MLT. Conclusively, findings in the present work provide a feasible technology for improving cryopreserved ovarian tissue quality through the addition of MLT to elicit HSP90 expression. [ABSTRACT FROM AUTHOR]

Cryopreservation of ovarian tissues (OTs) has become the most effective way to preserve the fertility of female cancer patients. However, cryopreservation of OTs is still relatively at an experimental stage. The aim of study is to examine the effect of melatonin (MTL) on cryopreserved-thawed OTs. Fragments of OTs were cryopreserved in medium containing different concentrations (0 mM, 0.001 mM, 0.01 mM, 0.1 mM and 1 mM) of MLT. The endogenous enzymes (GSH-PX, GSH, SOD, CAT and T-AOC), MDA and ROS levels were all evaluated after cryopreservation. Our results showed that the 0.1 mM of MLT significantly improved the survival and diameter of follicles (P < 0.001). Meanwhile, the antioxidant enzymes activities (including GSH-PX, GSH, SOD, CAT and T-AOC) were enhanced and MDA content were significantly decreased in 0.1 mM of MLT group compared to other groups (P < 0.001). Additionally, compared to the control group, MTL of 0.1 mM resulted in a significantly lower ROS level. In conclusion, MLT protects the quality of cryopreserved OTs by decreasing oxidative stress level and the optimal concentration is 0.1 mM. [ABSTRACT FROM AUTHOR]