CORRECTION BY PROLACTIN OF ELEVATED LEVEL OF ADRENAL 5α-REDUCTASE IN THE ANDROGEN INSENSITIVE (tfm) RAT PSEUDOHERMAPHRODITES (Ps)

Abstract

We have reported that Ps have a postpubertal elevation in adrenal steroid 5α-reductase activity characteristic of males castrated neonatally. In males the castration-induced defect can be corrected by testosterone, which requires the presence of the pituitary or by prolactin or growth hormone (Witorsch and Kitay, Endocrinol. 91:764, 1972). Radioimmunoassayed pituitary prolactin contents in the adults were significantly elevated over those of littermate males, but Ps serum levels of prolactin were not different. Prolactin (400 μG) was administered daily from 29-60 d of age to Ps and littermate males and females, and for 10 d to 5 mo. old Ps. Activity was determined as the total 5α-reduced labelled products from androstenedione and testosterone in adrenals taken from immature and adult animals. Prolactin significantly reduced 5α-reductase in Ps and males at all ages. The Ps may have a defect in the regulation of adrenal steroid synthesis by prolactin. This defect may be due to its insensitivity to the neonatal differentiating action of testosterone on the hypothalamic centers controlling prolactin.