Effect of Testosterone, Estradiol-17β and Progesterone on the Oxygen Uptake by Bovine Semen, Washed Spermatozoa and Epididymal-Like Spermatozoa

Abstract

The effect of testosterone, estradiol-17β and progesterone on the oxygen uptake of bovine spermatozoa in Tris-HCl buffer and saline (NaCl) media containing 500 mg per 100 ml fructose was determined. Testosterone significantly inhibited the oxygen uptake by freshly ejaculated semen, washed spermatozoa and epididymal-like spermatozoa. The effect was greatest with washed and epididymal-like spermatozoa, both of which have the seminal plasma removed. This effect was dependent on the dose of testosterone used with the most effective inhibitory concentration being 25 µg/2.5 × 10⁸ spermatozoa/ml. Estradiol-17β was stimulatory to the oxygen uptake of bovine semen and washed spermatozoa at a concentration of 10 µg/2.5 × 10⁸ spermatozoa/ml. Higher concentrations of estradiol-17β decreased the stimulatory effect and could become inhibitory. Progesterone tended to reduce oxygen uptake by whole semen and washed spermatozoa, but significant inhibition was only obtained when 100 µg progesterone per milliliter was added to whole semen. These steroids may have some direct effect on spermatozoa in vivo in addition to the indirect effects mediated through the reproductive systems.