THE EFFECT OF GROWTH HORMONE AND PROLACTIN PREPARATIONS ON THE CONTROL BY INTERSTITIAL CELL-STIMULATING HORMONE OF UPTAKE OF 65Zn BY THE RAT DORSOLATERAL PROSTATE

Abstract

SUMMARY Five pituitary hormones: follicle-stimulating hormone (FSH), adrenocorticotrophic hormone (ACTH), thyroid-stimulating hormone (TSH), growth hormone and prolactin, were tested for their capacity to alter the control by interstitial cell-stimulating hormone (ICSH) of the uptake of 65Zn by the dorsolateral prostate gland of the mature hypophysectomized Sprague-Dawley rat. Only prolactin and growth hormone produced significant augmentation of the response to ICSH. Contamination with growth hormone was apparently not responsible for the augmentation of ICSH activity brought about by the NIH-prolactin preparation used. NIH-prolactin and a highly purified preparation provided by Dr C. H. Li were shown to be equally effective in their capacity to augment the 65Zn-uptake response produced by ICSH. Augmentation was detectable with total doses of prolactin as low as 10–30 μg. (0·21–0·63 i.u.). Prolactin caused an augmentation of testosterone activity on uptake of 65Zn in the hypophysectomized and castrated rat, indicating an effect of prolactin on the prostate that is not mediated by the testis. NIH-growth hormone was not as effective as the prolactin preparations in enhancing ICSH activity, but in sufficient doses produced a significant increase in the 65Zn-uptake response to ICSH. These studies showed also that the uptake of 65Zn of the dorsolateral prostate was a more sensitive and more consistent parameter than glandular weight for the detection of augmentation of ICSH response by growth hormone or prolactin preparations.