Effects of Testosterone Administration on Testis and Serum Concentrations of Estradiol-17β in Immature Rats1

Publisher Website
Google Scholar
Abstract
Rat Sertoli cells produce estrogen (E2) in vitro when testosterone (T) is added to the medium. Our experiments sought to establish if the rat testis had this capability in vivo. Twenty-one-day-old rats were injected with T (6.25-200 µg. s.c./g BW) and killed 3 h later. Estradiol-17β was determined by RIA of samples which were first chromatographed on Sephadex LH-20. Rats injected with 50 or 100 µg/g BW of T had serum and testis E2 concentrations significantly greater than animals injected with smaller or larger doses of T or oil-treated controls and the 50 µg dose was more effective than the 100 µg dose. Animals castrated 12 h before being identically treated with a 50µ g/g BW dose of T, showed an increase in serum E2 which was not different from this response in the intact animal, indicating the testes of 21-day-old rats do not contribute significantly to the elevated serum E2 levels seen after injection of T in the intact rat. Injection of E2 (5 ng/g BW) into 21-day-old rats elevated serum E2, but did not alter testis E2 content. It is concluded the the prepubertal testis responds to exogenous T with increased E2 formation, most of which remains in the testis for at least 3 h.