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

ABSTRACT

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 H2 O2 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.