Effects of Prolactin, Growth Hormone and ACTH, Alone and in Combination, Upon Organ Weights and Adrenal Function in Normal Rats

Abstract

Groups of normal rats were injected for 10 days with large daily doses of prolactin (10 mg), growth hormone (10 mg) or ACTH (80 IU), or all 3 combined. Body weight and length were increased by prolactin as well as by growth hormone. The combination of all 3 hormones produced large milkfilled mammary glands and splanchnomegaly of the liver, kidney, heart and spleen. Kidney and heart weights were increased mainly by ACTH injection. ACTH alone increased adrenal weight and the blood corticosterone level 10-fold and reduced the adrenal ascorbic acid level to 100 mg/100 g. Relative to the effects of ACTH given alone, growth hormone and prolactin decreased the effect of ACTH on adrenal weight by 40%, and on blood corticosterone level by 50%. The adrenal ascorbic acid level was reduced to only 200 mg/100 g of adrenal weight in the rats receiving the 3 hormones. Depot fat was greatly reduced by all 3 hormones, while brown fat was increased by ACTH. Thymus weight was reduced by ACTH or combined hormone treatment. Pituitary weight was reduced about 40% by each of the hormones separately as well as by the combination. Injection of these 3 hormones in combination reproduced in intact rats the splanchnomegalic syndrome seen in rats bearing transplantable pituitary mammotropic tumors. (Endocrinology74: 714, 1964)