Effect of melatonin supplementation on cryopreserved sperm quality in mouse.

BACKGROUND: Antioxidants protect spermatozoa against cell damage during cryopreservation. OBJECTIVE: To investigate whether melatonin supplement in the extender may improve the quality of cryopreserved mouse sperm. METHODS: Kunming mice sperm frozen in extender R18S3 (18% (w/v) raffinose and 3% (w/v) skim milk) supplemented with melatonin were thawed and evaluated. RESULTS: Mouse spermatozoa were cryopreserved in the freezing extender R18S3 that contained melatonin at 0, 0.125, 0.25 and 0.5 mg/mL melatonin. The extender without melatonin supplement was associated with increased formation of reactive oxygen species (ROS) and decreased sperm motility. Melatonin supplement at 0.125 mg/mL significantly increased the progressive motility of sperm in comparison to other melatonin concentration or control. The percentage of thawed viable sperm with ROS was lower in the melatonin-treated groups than in untreated group. Melatonin supplement also increased antiapoptotic gene Bcl-xl expression in the thawed sperm. CONCLUSION: Supplement of 0.125 mg/mL melatonin could reduce oxidative damage and apoptosis.