Antioxidant Effects of Curcumin on the Motility and Structural and Biochemical Parameters of Epididymal Sperm in Shal Rams after the Freezing-Thawing Process

Background: Artificial insemination is widely used as a basic technique in livestock and poultry breeding programs.The use of this technique requires sperm freezing, a process during which superior genes are widely expanded and more progeny can be obtained from a male animal with high genetic characteristics.However, sperm undergoes much damage during the cooling and freezing process due to the drop in temperature and cold shock and the subsequent excessive production of free radicals.Lipid peroxidation (LPO) of the sperm plasma membrane occurs due to the production of reactive oxygen species (ROS), which damages the structure of the sperm membrane.The attack of free radicals on intracellular organelles, especially mitochondria and sperm DNA, can often disrupt sperm functions and have a very negative effect on sperm fertility.Therefore, adding antioxidant compounds to sperm thinners is considered essential for freezing and maintaining sperm quality.Curcumin, as a natural antioxidant compound obtained from turmeric root, with the characteristic of having a phenolic ring and a beta-di-ketone part in its structure, is capable of neutralizing free radicals and thus maintaining the quality of sperm cells.This compound has been introduced as a very strong antioxidant compound in most pharmaceutical, medical, and food industry studies, and even in some studies, it has been reported to be the co-base of known antioxidant compounds, such as vitamins E and C, and the superoxide dismutase enzyme.This experiment aimed to investigate the effects of adding different levels of curcumin to diluents on the physical, structural, and biochemical parameters (oxidative stress) of ram epididymal sperm after the freezing-thawing process.Methods: In this experiment, testicular tissue was collected from a slaughterhouse and transferred to the laboratory.Sperm cells were collected by cutting the tail of the epididymis.Sperm samples were selected after an initial evaluation and diluted in a Tris-egg yolk-based diluent with a concentration of 50 million sperm per milliliter.Different concentrations of curcumin, including 0, 10, 25, and 50 M, were added to the sperm-containing diluent at 37 C.Samples containing different concentrations of curcumin in different experimental groups were poured into a 15 ml Falcon and transferred to 5 C in isothermal water for cooling.After about 2 hours, the samples reached equilibrium at this temperature.Then, the experimental groups were filled and sealed at the same temperature in one-quarter straws at the same temperature.The peyotes were frozen at a distance of 4 cm from the surface of liquid nitrogen by nitrogen vapor for 7 minutes and then immersed in liquid nitrogen.The frozen peyotes were kept in a nitrogen tank until the evaluation (about 1 month).Physical parameters, survival, apoptosis status, plasma membrane health, abnormality percentage, biochemical parameters (including measurement of malondialdehyde (MDA) concentration, activity of superoxide dismutase enzymes (SOD), glutathione peroxidase (GPX), and catalase (CAT), and H2O2 concentration assay were evaluated after thawing at 37 C for 30 seconds.The data obtained from the evaluations were analyzed by SAS software and the GLM procedure at a significance level of 0.05.Results: The results of kinematic parameters, such as the total kinematics (TM) of the diluent containing 10 and 25 M curcumin, the progressive kinematics (PM) of the diluent containing all three concentrations of curcumin (10, 25, and 50 M), and the speed in the mean path (VCL) diluent containing 25 M of curcumin, showed significantly better performance than the control group (p < 0.05).However, no significant differences were observed between the experimental