Amilorating effects of cysteine, glutathione and taurine during freezability of ram spermatozoa

Abstract

Ram sperm have a higher ratio of polyunsaturated/saturated fatty acids and a lower ratio of cholesterol/phospholipids molar than other species, which renders the sperm much more vulnerable to oxidative damage caused by reactive oxygen species (ROS) .The aim of the current study was to evaluate the effects of cysteine, glutathione and taurine on the freezability of ram spermatozoa and biochemical parameters. Semen samples from ten mature mixed Barki rams were used in this study. Pooled semen samples were divided randomly into 7 aliquots one was diluted with a Shotor extender as a control basal diluent while others in addition to basal extender L-Cysteine, L- reduced glutathione and taurine were added by two levels for each to present seven experimental groups. Diluted semen cooled to 5^oC then frozen by liquid nitrogen in 0.25 ml French straws. After 48 hr frozen, straws were then thawed individually at 37 ^oC for 30 sec. in a water bath then subjected to evaluation. The obtained results showed that, addition of glutathione by a rate of 5mM was significantly increases motility than control group. Similarly, addition of taurine by a rate of 50mM significantly

increased the viability index of cryopreserved semen samples. Percentages of acrosomal defects were dramatically decreased (P < 0.05) with glutathione (10 mM) addition compared to control (9.00 ± 1.16 % and 21.00 ± 0.58 % respectively) In regards to sperm membrane integrity, cysteine (5 mM) provided a greater protective effect (47.00 ±1.16) compared to control (%, 35.33 ± 0.88 %). Antioxidant addition showed decreased enzyme leakage and significantly (P < 0.05) improved total antioxidant capacity (TAC) especially taurine (50Mm) compared to control group. In regards to DNA integrity, taurine (50mM) provided a significant protective effect (98.51± 0.42 %) compared to control. Findings of this study showed that addition of cysteine, glutathione and taurine to semen extenders, of greater benefit to quality of frozen-thawed ram sperm. However further investigation on their effect on fertilizing capacity and pregnancy rate still needed.