Glutamine protects rabbit spermatozoa against oxidative stress via glutathione synthesis during cryopreservation.

Mammalian spermatozoa are extremely susceptible to high doses of reactive oxygen species (ROS). The aim of the present study was to investigate the potential role of glutamine in protecting rabbit spermatozoa against ROS stress during cryopreservation and post-thaw incubation. Freshly ejaculated semen was diluted with Tris-citrate-glucose extender supplemented with glutamine. The addition of 20mM glutamine significantly improved sperm motility, acrosome integrity, membrane integrity and mitochondrial activity. Meanwhile, 20mM glutamine addition decreased lipid peroxidation and DNA damage in frozen-thawed spermatozoa. Interestingly, supplementation with 20mM glutamine led to increases in glutathione content and γ-glutamyl cysteine synthetase and glutathione peroxidase activity, with concomitant decreases in ROS levels during cryopreservation and post-thaw incubation. In conclusion, the addition of glutamine to extender solutions protects rabbit spermatozoa from ROS attack by enhancing glutathione synthesis.