Effect of melatonin supplementation on sperm quality parameters and expression of antioxidant genes during cold storage of buck semen extenders

Background and Aim: Semen storage is an important reproductive method used in artificial livestock breeding. However, oxidative stress during storage reduces the quality of sperm. Melatonin supplementation in semen storage medium has not been well studied, but it has been shown to protect cells from oxidative stress. Therefore, this study aimed to determine the effect of melatonin supplementation on sperm quality parameters and antioxidant gene expression levels in semen extenders during cold storage. Materials and Methods: Semen extenders with melatonin concentrations of 0 (control), 0.1, 0.2, and 0.3 mM were added as treatment. The treated semen was then stored at 5°C for 72 h using a cold storage method, and quality parameters, including percentage of progressive motility, membrane integrity, intact acrosome, and DNA integrity, were measured every 24 h. In addition, messenger ribonucleic acid abundance levels of glutathione peroxidase (GPx) and superoxide dismutase (SOD) genes were sampled after 0 and 72 h of cold storage. Results: All observed sperm quality parameters decreased with increasing cold storage time; however, 0.2 mM melatonin demonstrated superior protection of sperm quality during cold storage. Gene expression analysis showed that GPx levels decreased significantly (p < 0.05) after 72 h in semen without melatonin but not in the melatonin-treated groups. A similar trend was also observed in SOD, indicating that exogenous antioxidants effectively protected the sperms. Conclusion: Melatonin supplementation at 0.2 mM in semen extenders during cold storage maintains sperm quality parameters for up to 72 h because melatonin protects sperm from oxidative stress. These findings can be used to improve the semen storage protocol by combining semen extender and antioxidant. Keywords: antioxidant gene expression, melatonin, semen cold storage, sperm quality.