EFFECT OF GROWTH HORMONE AND THYROXINE ON BODY WEIGHT OF HYPOPHYSECTOMIZED C3H MICE1

Abstract

Bovine growth hormone was administered to hypophysectomized female C3H mice at increasing dose levels to maintain continuous growth. Within a period of 25 weeks the initial weight of the animals had doubled. Plateauing was observed at all dose levels, but gains could always be reinitiated by increasing the dose level. Although thyroxine was ineffective as an independent growth factor, when administered at a daily dose level of 0.0003 mg together with growth hormone for longer than 8 weeks, it did act as a synergist with the latter in effecting body weight increases. When thyroxine in increasing dose levels was administered together with growth hormone, toxic effects were observed. 0.003 mg of thyroxine plus growth hormone produced enlarged adrenal glands in all the mice so treated; from histological sections of the gland it was apparent that the enlargement could be attributed primarily to the extensive development of one region of the adrenal cortex, the juxtamedullary zone.