Growth of Hypophysectomized Rats Injected with Growth Hormone and Fed on Different Proteins

Abstract

A few studies, , , , dealing with the relationship between the hypophysis and nutrition have been reported, but no systematic investigation on the nutritional requirements of hypophysectomized rats has yet been made. In this communication are recorded our preliminary results of the growth studies of hypophysectomized rats fed with proteins of different nutritive values. Method The procedure for the growth study is essentially that of Osborne and Mendel. Five groups (10 animals each) of hypophysectomized rats were fed isocaloric diets containing 30% test proteins, 32% Amidex 24% crisco, 2% Cod Liver Oil, 8% yeast, and 4% of a salt mixture. The vitamin supplements for each one hundred grams of the diet are: The food consumption and the weight of the test animals were recorded twice weekly. During the entire test period of three weeks, the animals received subcutaneously 0.1 mg of a purified growth hormone preparation, isolated from beef pituitary glands, every morning. Results The data (see the accompanying table) demonstrate that animals on a proteinfree diet failed to survive for even a week in spite of their average consumption of approximately 5 g per rat per day. In contrast with this the normal, unoperated rats of the same age survived for more than 2 weeks on the same protein-free diet in spite of their gradual loss of weight. The weights of animals on the test protein diets increased significantly. The increase was the smallest for soya protein diet and the greatest for the casein diet, even though the animals on soya protein consumed approximately the same amount of food as the animals on either the vitamin-free casein or lactalbumin diets. After the second and third weeks of feeding, the food consumption by rats of all groups dropped markedly.