Effect of different concentrations of melatonin on ram epididymal spermatozoa recovered post-mortem under oxidative stress conditions and storage at 4°C.

The current study examines the protective effects of different melatonin concentrations on fresh ram epididymis spermatozoa after post-mortem recovery under normal and oxidative stress conditions and during liquid preservation (4°C) at different times (24, 48 and 72 h). The testes were obtained from a local slaughterhouse during the breeding season. Spermatozoa were isolated from cauda epididymides. In experiment 1, the effects of adding different concentrations of melatonin (0, 15, 60 and 240 μg/ml) under normal and oxidative stress conditions were evaluated. Fifty μM of hydrogen peroxide was used to induce oxidative stress. Also, in experiment 2, the spermatozoa samples were chilled to 4°C and stored for 72 h. Sperm total motility, viability, membrane, DNA integrity and morphological abnormality were evaluated at 0, 24, 48 and 72 h after cooling storage. In experiment 1, melatonin treatment preserved viability increased TAC and SOD activities, and reduced MDA levels compared with control. Also, melatonin reduced the harmful effects of H O under induced oxidative stress. In experiment 2, melatonin at concentrations of 15 and 60 g/ml greatly increased sperm viability after 3 days of cold storage. Furthermore, it could have a significant protective effect on the motility of cooled sperm. Melatonin supplementation preserved higher sperm membrane integrity at concentrations of 15 and 60 μg/ml, DNA integrity at a concentration of 15 μg/ml and abnormality at a concentration of 60 μg/ml after 3 days of storage. The results suggest that melatonin can be used to reduce the adverse effects of induced oxidative stress in spermatozoa. Furthermore, ram epididymal spermatozoa could be stored at 4°C for 72 h when treated with melatonin.