EFFECT OF EARLY HYPOPHYSECTOMY ON HYPOTHALAMIC OBESITY1

Abstract

Certain large, bilateral symmetrical hypothalamic lesions not involving the hypophysis cause rats to become markedly obese. Such lesions placed in a group of young rats which were hypophysectomized about a wk. later still caused the animals to attain a high degree of adiposity. Serial histological sections of the sella and the neighboring region proved the majority of these fat dwarf rats were completely hypophysectomized. Taken together with the evidence that hypophysectomy, stalk section, or destruction of the infundibular region do not cause adiposity, these results are interpreted as indicating that hypothalamic control of fat metabolism, and the dysfunction of that control which leads to adiposity, do not depend upon the hypophysis. Apparently even the presence of the pituitary is non-essential to the appearance of hypothalamic obesity. The response is caused by the severance of pathways which descend from the hypo-thalamus through the brain stem.