Influence of intragastrically administered androgens on hypothalamic differentiation in rats.

Male and female rats aged 3 days were injected intragastrically with methyltestosterone and STS 383 synthetic androgen in doses between 0.4-3.2 mg and 0.2-3.2 mg, respectively. The treated females showed disturbances in hypothalamic differentiation as demonstrated by changes of the day of vaginal opening and frequency of oestrus, by a decrease of ovarian weight and a loss of fertility. It is thus possible to investigate perorally active aromatizable androgens for their central activities. STS 383, a new p. o. active androgen showed a higher activity compared with methyltestosterone in this study, whereas in the Hershberger model methyltestosterone was previously found to be 4 times more active than STS 383. A possible dissociation of central and peripheral activities between these two substances is discussed.