Effects of testosterone, pregnenolone, progesterone and cortisol on pituitary and testicular function in male golden hamsters with gonadal atrophy induced by short photoperiods.

Testicular regression was induced in adult golden hamsters by exposure to a short photoperiod (5 h light:19 h darkness). The response of these animals to exogenous steroids (ten injections each of 5 mg testosterone, testosterone propionate, pregnenolone, progesterone or cortisol administered s.c. three times/week) was evaluated from weight changes in testes and seminal vesicles, from plasma levels of LH, FSH and testosterone, and from testicular human chorionic gonadotrophin (HCG) binding and testosterone levels. Administration of testosterone or testosterone propionate produced a decrease in plasma gonadotrophins and a three- to fourfold increase in weights of testes and seminal vesicles, thus indicating that the seminiferous tubules, similarly to accessory reproductive glands, retained the ability to respond to androgenic stimulation. Binding of HCG by testicular tissue was dramatically reduced by treatment with testosterone, probably reflecting atrophy of the Leydig cells. Treatment with pregnenolone or progesterone failed to increase testicular weight, seminal vesicle weight or concentrations of in the testes. This suggests that the atrophic testes of these animals may have a limited capacity to produce biologically significant amounts of androgens from C21 steroids. Administration of cortisol did not alter any of the parameters of reproductive function that were examined.