Effect of reduced glutathione and superoxide dismutase antioxidant levels on some of the characteristics of sperm after freezing bull semen
2017
Daghigh Kia, Hossein | Olfati Karaji, Rasteghar
BACKGROUND: Semen cryopreservation process with increased reactive oxygen species levels (ROS) plays a decisive role on the sperm cellular organelles (cell membrane, mitochondria and DNA). OBJECTIVES: The aim of this study was to determine the effects of adding different levels of superoxide dismutase (SOD) and reduced glutathione (GSH) antioxidants before freezing on motility, total progressive motility, viability and positive response to hypo-osmotic swelling test (HOST) parameters after Bull semen was frozen. METHODS: In this study, four bulls aged 4-5 years were used and 20 times the semen collection (5 ejaculates per bull) was performed. SOD (100 and 150 IU/ml) and GSH (5 and 7.5 mM) antioxidants were added to Tris - egg yolk extender. Diluted semen samples with or without additives were manually filled with straw and the free end of the straws were sealed by sealing machines; then, semen were frozen by semi-automatic freezing machine, using liquid nitrogen. After thawing the samples, the total and progressive motility, sperm viability and positive response to the HOST parameters were determined at zero and 2 h of incubation. RESULTS: Adding SOD and GSH antioxidant levels did not reveal significant differences between treatments in any of the semen parameters in the initial hour of incubation after thawing. Two hours incubation of post-thawed semen samples containing SOD (100 IU/ml) significantly improved total motility, viability and membrane integrity of the sperm (p<0.05). Also, in samples containing SOD (150 IU/ml), sperm membrane integrity was maintained (p<0.05). In the semen samples with antioxidant GSH (5 mM), total motility and membrane integrity of the sperm are considerably improved after thawing (p<0.05). CONCLUSIONS: This study showed that using SOD and GSH antioxidants as freezing semen extender additives can improve post-thawed bull semen quality.
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