| Abstract: | At the University of Missouri-Kansas City, School of Dentistry, the effect of mestranol and/or norethynodrel on growth hormone (GH) was studied with an anterior pituitary gland (AP) donor-recipient technique in rats. Experimental donor rats received, per 100 g of body weight, subcutoneous injections of 50 mcg of mestranol (16 rats), 1250 mcg of norethynodrel (18), or their combination (23) on Monday, Wednesday, and Friday for 10 weeks. 12 control donor rats received vehicle alone. P values greater than .05 were considered significant. Mean final body weight, body weight gain, and absolute AP weight of the 3 steroid-treated donor groups were significantly less than the control values. Body sizes in the 3 donor groups were markedly smaller than in the control group. The effect of donor AP given in ip injections to hypophysectomized recipient rats was studied by measurement of the tibial epiphyseal cartilage width. Judged in this indirect manner, total GH in the AP was seen to be significantly decreased by all 3 steroid treatments but still present in moderate amounts. The treatments may have, directly or indirectly through the hypothalamus, inhibited pituitary GH synthesis and release, or the decreased total GH in the AP may have been due simply to the significant decrease in gland size. The estrogenic activities of mestranol and norethynodrel may have been responsible for an inhibition of GH synthesis. On the other hand, the steroids may have stimulated GH release from the AP as is the case in humans but concurrently exerted antagonistic action on GH at the level of peripheral tissues. |
