Selenium-75 Incorporation in Semen and Reproductive Organs of the Bull and Ram

approved: Redacted for privacy Philip D. Whanger Following initial intramuscular injections of 500 pCi 75 Se, semen was collected periodically by electroejaculation over a 63 day period from a selenium-deficient and a selenium-adequate ram. Ten and three days prior to necropsy, second and third injections of 500 11Ci were given. Testes, accessory glands, and semen were obtained from a bull injected with 75 Se through the courtesy of the Animal Science Department of Washington State University, Pullman, Washington. Gel filtration of ram testis cytosol resulted in four 75 Se peaks (Ve/Vo ratios of 1.09, 1.52, 2.30, and 2.85). In the seleniumadequate ram the GSH-Px peak (Ve/Vo 1.52) predominated, but in the selenium-deficient ram, radioactivity of the GSH-Px peak was less than that of the higher molecular weight peak (Ve/Vo 1.09). Gel 75 filtration chromatograms of bull testis cytosol showed five 75Se peaks (Ve/Vo ratios 1.11, 1.48, 1.90, 2.41, and 2.78). In chromatograms of ram seminal plasma there were two major 75 Se peaks (Ve/Vo ratios of 1.06 and 1.40), and two minor peaks (Ve/Vo ratios 1.73 and 2.42). Percent 75 Se associated with the peaks changed with time after injection. Se-labeled bull seminal plasma showed two 75Se peaks (Ve/Vo ratios of 1.09 and 1.42) which corresponded to the major peaks of ram seminal plasma. Bull and ram seminal plasma glutathione peroxidase activities per mg protein were comparable (27.73 and 28.97 nmoles NADPHox, respectively), but when expressed per ml seminal plasma, activity of the bull was greater than seven times the highest activity of ram seminal plasma (2908 and 385 nmoles NADPHox, respectively). Seminal vesicles of bull and ram, and the bull prostate gland possessed high glutathione peroxidase activity. The Cowper's glands of bull and ram had low activity of this selenoenzyme. Incorporation of 75Se into ram sperm occurred prior to and during the early spermatid stage. Electron autoradiography of ram sperm indicated an affinity of membranes for selenium. The nucleus also demonstrated an incorporation of selenium. The implications of these findings are discussed. Selenium-75 Incorporation in Semen and Reproductive Organs of the Bull and Ram