THE PRODUCTION OF HYPOTHALAMIC OBESITY IN RATS ALREADY DISPLAYING CHRONIC HYPOPITUITARISM

Abstract

Ten rats hypophysectomized and observed for periods of about 11 wks. showed no signs of developing obesity. Some, even after so long a time, had not even attained their preoperative wt.; others had surpassed it only by a few gs. While in a state of chronic hypophysial insufficiency, hypothalamic lesions were produced by the Horsley-Clarke technic. Within 3-4 wks. they began to display rapid fat deposition, and 11 wks. after the 2d operation they were markedly obese. Hence the fat depots are still able to store excess fat in response to hypothalamic damage even after they have suffered the changes in tissue metabolism presumed to be attendant upon hypophysectomy. Since neither total nor partial hypophysectomy produces adiposity, or prevents its appearance after hypothalamic damage is done, it is not likely the hypophysis is involved in the production of obesity often associated with injury to structures in the pituitary region. Hypothalamic disorder appears to be the sole responsible factor.