Androgens in female pig reproduction: actions mediated by the androgen receptor

Androgens have potential actions in almost all the organs of males and females. In females, most organs contain some tissues with cells that have androgen receptors. Androgens can regulate cellular functions by binding to androgen receptors or be converted to other hormones. For example, testosterone can bind to the androgen receptor or be aromatised to oestradiol. Treating animals with testosterone, therefore, might elicit some androgenic and oestrogenic effects. Alternatively, testosterone can be converted to other androgens, which in turn, have more or less affinity with the androgen receptor and these new metabolites may or may not be aromatised to oestrogens. This review will highlight the roles of androgens in female mammals other than those as a substrate for oestrogen, with particular emphasis on the actions of the androgen receptors in uteri and ovaries of pigs. Utilising small dosages of an androgen receptor agonist, DHT (5alpha-dihydrotestosterone) we have observed that some uterine functions were inhibited while ovarian follicular development was augmented. These inhibitory and stimulatory effects of androgen therapy on reproductive organs can potentially be balanced to enhance ovulation rate and litter size in gilts and sows. Perhaps after future experimentation, new uses of androgens or anti-androgens could improve additional aspects of sow performance not presently under consideration.