Glutathione peroxidase and selenium distribution in semen and reproductive tissues of farm animals

Graduation date: 1982This study was conducted to investigate the distribution\ud of glutathione peroxidase (GSH-Px) and selenium in\ud semen of the boar, bull, ram and stallion, and in the reproductive\ud tissues of the boar, bull and ram. The effect\ud of repeated noncryoprotective freeze-thawing on GSH-Px\ud activity was also studied. Both hydrogen peroxide (H₂0₂)\ud and tetra-butyl hydroperoxide (t-butyl 0₂) were used as\ud substrates for the enzyme.\ud Most of the GSH-Px activity in semen of the four species\ud examined was associated with seminal plasma. GSH-Px\ud activities in the spermatozoa of these species were comparatively\ud very low. There were species and tissue\ud differences in the distribution of GSH-Px in reproductive\ud tissues. Determined per mg protein, GSH-Px activity was\ud highest in the testis, whereas the Cowper's gland and\ud ampulla showed the least enzyme activity. In general,\ud GSH-Px levels in the reproductive tissues of the bull were higher than, or comparable to, those of the ram. The\ud reproductive tissues of the boar showed the least GSH-Px\ud activity.\ud The GSH-Px determined in this study showed a similar\ud magnitude of response to both H₂0₂ and t-butyl 0₂ and had\ud a high correlation with tissue and fluid selenium levels.\ud This demonstrates that the GSH-Px found in semen and\ud reproductive tissues of the boar, bull and ram is a\ud selenium-dependent enzyme.\ud Repeated freezing (at -21°C) and thawing, in the\ud absence of appropriate buffers, led to a decline in seminal\ud plasma and reproductive tissue GSH-Px activities.\ud Selenium distribution in semen and reproductive\ud tissues differed among the species studies. On the basis\ud of selenium concentration per billion sperm cells, boar\ud spermatozoa had the highest selenium concentration followed\ud by those of the stallion, bull and ram in that order.\ud Bull seminal plasma, however, had more selenium than that\ud of any of the other three species. The testis and\ud epididymis had the greatest concentration of selenium\ud found in the reproductive tissues. Levels of selenium\ud in semen and reproductive tissues were significantly higher\ud (P