The Effect of Growth Hormone on Hematopoiesis in Hypophysectomized Adult Female Rats1

THE fact that hypophysectomy is followed by an anemia is well established. This has been found to be true for every animal investigated as well as for the human being. Growth hormone has been one of several hormones used as a therapy to prevent this anemia but with confusing results. Meyer, Stewart, Thewlis, and Rusch (1) found that growth hormone would stimulate bone marrow so that the reticulocyte number was greatly increased, but the erythrocyte count was not altered. Gaebler and Mathies (2) found that growth hormone had no effect on the hemoglobin level of hypophysectomized rats. Van Dyke, Simpson, Garcia, and Evans (3) also were unable to prevent post-hypophysectomy anemia with daily injections of 1.25 mg. of growth hormone for 30 days. The erythrocyte count, hematocrit percentage, hemoglobin level, and the total cell volume per 100 gm. of body weight were not changed from levels exhibited by the the untreated hypophysectomized rats. Crafts (4) reported similar results with gradually increasing doses of growth hormone, starting with 0.1 mg. per day and gradually increasing to 0.8 mg. daily. Gemzell and Sjostrand (5) measured the total amount of hemoglobin in hypophysectomized rats and in hypophysectomized rats treated with growth hormone.