Effect of neonatal testosterone and oestradiol treatment on the development of the hypothalamo-hypophysial axis in the female rat

Abstract

The hypothalamic LH-RH [luteinizing hormone-releasing hormone] content and the concentrations of pituitary and plasma LH [luteinizing hormone] were measured at various ages in female rats treated daily with 10 .mu.g testosterone propionate or 10 .mu.g estradiol-17.beta. from birth to Day 15. Persistent vaginal oestrus was induced in all the treated rats. Both hormones significantly reduced the hypothalamic LH-RH content and pituitary and plasma LH concentrations. Hypothalamic LH-RH increased after cessation of treatment, pituitary LH did not return to normal levels. Plasma LH levels were significantly lower than those in control rats. Testosterone propionate and estradiol-17.beta. may have a direct negative feed-back influence on the hypothalamus in the neonatal female rat, alter the normal pattern of plasma and pituitary LH in developing female rats, prevent the cyclic secretion of plasma LH after maturity and cause a chronic impairment in the release of LH-RH.