Status of prooxidant and antioxidant systems in the sperm and seminal plasma of breeding boars of large white breed and SS23 synthetic line.

The indicators of pro- and antioxidant systems in sperm and sperm plasma of breeding boars of Large White breed and SS23 synthetic line were studied. Measurements of antioxidant enzyme activity, determination of lipid peroxidation (LPO) product content, and antioxidant factor were performed. Lipid peroxidation in the semen of healthy breeding boars was characterized by a stable level of activity, which is necessary to ensure normal reproductive functions. Additionally, there was a high content of low molecular weight thiols and proteins. The concentration of SH-groups in spermatozoa was higher (P≤0.05) compared to sperm plasma. The number of total, protein, and free SH-groups in the semen of boars of the synthetic line was higher (P<0.05) in relation to animals of the Large White breed. Low catalase (CAT) activity in the sperm was compensated by glutathione peroxidase (GPX). The content of ceruloplasmin (CP) in the sperm of boars was almost twice as high as that of sperm plasma. In spermatozoa, high content of reduced glutathione (GTH) was recorded, which was more than 3 times higher than in the seminal fluid. The main antioxidants of spermatozoa were superoxide dismutase (SOD), CP, SH-groups of proteins, and reduced content of GTH. We revealed that CAT is a key enzyme that neutralizes excess hydrogen peroxide in boar semen. In contrast, in sperm, hydrogen peroxide was inactivated mainly by GPX. Further research on the mechanisms of action of reactive oxygen species on boar semen will help to develop effective methods for sperm storage and successful fertilization of oocytes.