Behavioural and morphological effects of 5 -dihydrotestosterone and oestradiol-17 in the prepubertally castrated boar

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Abstract
Three groups of 5 prepubertally castrated boars received twice weekly s.c. injections at 16-28 wk of age of 5.alpha.-dihydrotestosterone propionate (1 mg/kg), estradiol-17.beta. dipropionate (0.1 mg/kg), or a combination of the 2 steroids. The pigs were tested each week for sexual behavior with an estrogen-treated ovariectomized gilt. 5.alpha.-Dihydrotestosterone did not induce copulatory behavior whereas estradiol initiated mounting, although this behavior was not maintained. The combined hormonal treatment induced the full pattern of copulation, including ejaculation, in 4/5 pigs. Estrogen-treated animals also showed champing and salivation. None of the pigs treated with 5.alpha.-dihydrotestosterone showed lordosis when exposed to a mature boar. Increases in the size of the penis, the ischio- and bulvocavernosus muscles, seminal vesicles and bulourethral glands were produced by 5.alpha.-dihydrotestosterone, and, with the exception of the penis, this hypertrophy was further enhanced by additional treatment with estradiol. Increases in the weight of the prostate and muscular urethra were due mainly to the effects of estrogen; this steroid caused extensive development of fibromuscular tissue and also increased mammary teat length. In the submaxillary salivary glands, synergism between 5.alpha.-dihydrotestosterone and estradiol resulted in hypertrophy of the serous cells.