EFFECT OF INSULIN ON BODY GROWTH AND MAMMARY GLAND DEVELOPMENT IN FORCE-FED HYPOPHYSECTOMIZED RATS INJECTED WITH OVARIAN HORMONES

In 1953 Salter & Best reported that injections of slow-acting insulin in gradually increasing amounts produced a marked increase in the body weight of hypophysectomized rats. This effect of insulin was dependent upon the composition and amount of food consumed (Salter et al., 1957). Since an increase in the body weight has also been found in hypophysectomized rats tubefed large amounts of food (Samuels et al., 1943, Levin, 1944) the question arose whether, in the experiments of Salter & Best, the only effect of insulin was to stimulate the appetite and increase the food intake. To answer this question Wagner & Scow (1957) studied the effect of insulin on force-fed hypophysectomized rats. In such rats administration of 2–3 units of insulin daily had no additional effect on body weight, body length or body composition, and Wagner & Scow suggested therefore that »exogenous insulin acts as a growth stimulant in hypophysectomized