Paul Han

The size, number, and rate of formation of mature adipocytes were studied in the epididymal pads and retroperitoneal adipose depots of the Sprague-Dawley rat. Early growth of these depots was accompanied by progressive enlargement of adipose cells as well as by increases in number. Beyond the 15th wk of life, the depot grew exclusively by the process of cellular enlargement, with no further change in cell number. Severe starvation during the 6th wk of life followed by normal feeding had no lasting effect on cell size or cell number; prolonged semistarvation beginning in the 15th wk greatly reduced cell size while cell number was unaffected. Likewise, extreme increases in depot size produced by hypothalamic lesions did not change cell number, but only cell size. The concept of a fixed number of mature adipocytes in the adult organism may be of central importance in caloric and metabolic equilibrium.

Bilateral hypothalamic lesions were placed in the ventromedial nuclei of 15 male weanling rats. Nine male littermates were used as controls. Food intake, body weight, and nose-occipital (N-O) length were followed for 90 days. Rats were killed on the 90th postoperative day and stomach weight, body fat content, and femur length were then measured. Although the daily food intake and the rate of body weight gain of the rats with lesions were comparable to those of their controls, all 15 operated rats became obese and their N-O and femur lengths were significantly shorter. It is concluded that hypothalamic obesity of weanling rats is associated with growth impairment.

The effects of Carica papaya Linn on exogenous ulcer and histamine-induced acid secretion were studied in rats. The latex of the unripened fruit of C. papaya was effective in protecting the exogenous ulcer. It significantly lessened the acid secretion induced by intravenous infusion of histamine in chronic gastric fistulated rats. Crystalline papain was also effective in protecting the exogenous ulcer and in decreasing the histamine-induced acid secretion in rats. The conclusion is that papain is the active principle in C. papaya that exerts the ulcer-protective effect.

Temperature regulation was studied in rats with bilateral hypothalamic lesions, by observing body temperature responses to the heat stress of forced exercise, and to exposure to hot or cold environments. Lesions in the preoptic area caused impairment of heat loss mechanisms but no disturbance of regulation against cold. Lesions in the lateral hypothalamic area caused no disturbance of regulation against cold; regulation against heat exposure was also not significantly altered, but the cause of a higher T-cut observed after exercise could not be explained. Lesions in other parts of the hypothalamus, with the exception of the ventromedial nuclei, did not cause changes in the normal pattern of temperature response to forced exercise.