A study of some major testicular steroids in the pig in relation to their effect on the development of male characteristics in the prepubertally castrated boar.

Prepubertally castrated boars received subcutaneous injections twice weekly, from 12 to 38 weeks of age, of testosterone or 5-androstenediol (5-androstene-3 beta,17 beta-eiol) (2 mg/5 kg), or each of these steroids in combination with oestrone (1 mg/5 kg). All steroid treatments induced growth and secretory activity of the accessory organs. The prostate was maintained best by testosterone, and the seminal vesicles by 5-androstenediol. No specific effects of oestrone on these organs were found. Champing of excess saliva was induced in all treated pigs when they were introduced to an oestrous gilt, but only boars receiving testosterone displayed intense mating behaviour including mounting and, in 3 animals, ejaculation; no specific effects of oestrone on behaviour were seen. Low normal levels of unconjugated androgen, and normal to high levels of unconjugated oestrogen were circulating in the treated pigs. There was evidence that peripheral metabolism of exogenous steroids had occurred: 5-androstenediol to testosterone, these two androgens to oestrogen, and sulphation of oestrogen. The sulphate conjugates of dehydroepiandrosterone, 5-androstenediol and oestrone predominated in the peripheral plasma of mature intact boars. Concentrations of 3 alpha-androstenol (5 alpha-androst-16-en-3 alpha-ol) in the submaxillary glands of androgen-treated pigs were similar to those in untreated castrates, thus indicating that androgens are probably not precursors of the pheromonal 16-androstene steroids in vivo.