Androgen and estrogen metabolism in the reproductive tract and accessory sex glands of the domestic boar (Sus scrofa)

Abstract

Steroid metabolism in target tissues has relevance in assessing biological response. We have investigated the metabolism of testosterone and estrogens in the reproductive tract and accessory sex glands in the boar. Seminal vesicles were taken from four 6-mo-old animals; and seminal vesicles, prostate, ras deferens, and regions of the epididymis were taken from two mature boars (10 and 24 mo old). Tissues were incubated in 5 ml medium (TC- 199) at 34°C under 5% CO2 and 95% air for 2 h with 3H-labeled testosterone, estrone, and estradiol-17β. Aliquots of spent media were taken to measure radioactivity before separation of unconjugated and conjugated steroids on Waters C18 Sep-Pak cartridges. Sulfoconjugated steroids and glucuronidates were recovered in series from C18 cartridges after solvolysis and enzyme hydrolysis, respectively. Profiles of metabolites for free and hydrolyzed fractions were obtained from gradient HPLC with acetonitrile:water on a reversed-phase C18 column. No clear evidence of conjugation was seen for testosterone metabolites. 5α-Dihydrotestosterone was the principal metabolite, but the amounts formed depended on the source, with little from the epididymal tissues and seminal vesicles, but greater quantities from the vas deferens (> 25%) and prostate (> 30%). The most noteworthy feature of estrogen metabolism was the extent of conjugation by all tissues. Almost all radioactivity in the conjugate fractions for the epididymis and vas was present as sulfates. Glucuronidates were seen for the prostate and were the dominant form of conjugation (about 60%) for the seminal vesicles. A striking parallel existed for the profiles of estrogen metabolites from all tissues for unconjugated and hydrolyzed fractions. Only in quantitative terms were some distinctions noted. These overall findings underscore a need to consider local metabolism of steroid hormones in target tissues of the male reproductive system.