Comparison of ovarian and hypothalamic obesity syndromes in the female rat: effects of diet palatability on food intake and body weight.

Both ovariectomy and hypothalamic knife cuts produced hyperphagia and obesity in adult female rats. The ovarian obesity, however, unlike hypothalamic obesity, was virtually independent of diet palatability. Ovariectomized rats became obese on quinine-adulterated diets, which completely blocked hypothalamic obesity, and they displayed little further weight gain when given a high-fat diet, which greatly potentiated hypothalamic obesity. Ovarian and hypothalamic obesity were also found to be additive irrespective of diet condition when both surgical treatments were combined in the same animal; that is, ovariectomy increased the food intake and body weight of knife-cut animals given the quinine or high-fat diet. In contrast to their dissimilar feeding effects, ovariectomy, hypothalamic cuts, and the combined surgeries, did not differentially alter the aversion to a .01% quinine solution. The results indicate that ovarian obesity and hypothalamic obesity represent two different feeding disorders and are mediated by separate neural mechanisms. The functional nature of these disorders is discussed in light of recent body weight set point interpretations.