AJP - Endocrinology and Metabolism, Vol 239, Issue 6 437-E441, Copyright © 1980 by American Physiological Society
Hypothalamic obesity in female rats in absence of vagally mediated hyperinsulinemia
B. M. King, G. R. Phelps and L. A. Frohman
In order to assess the role of vagally mediated hyperinsulinemia in
hypothalamic obesity, plasma insulin and glucose levels were assayed in
vagotomized and sham-vagotomized female rats after a 6-h fast and after a
measured glucose meal both before and 10-14 days after ventromedial
hypothalamic (VMH) lesions. Both groups displayed similar gains in body
weight in the first 10 days after VMH lesions, but only the
sham-vagotomized VMH-lesioned animals displayed elevated fasting insulin
levels. Fasting glucose levels did not differ either before or after the
lesion. The insulin response to oral glucose was increased in VMH rats,
both in vagotomized and sham-vagotomized animals, and it is concluded that
the hyperresponsiveness to oral glucose is independent of vagal mediation.
Vagotomy markedly exaggerated the glucose and insulin response to oral
glucose loading in both intact rats and rats with VMH lesions, probably as
a result of more rapid absorption of glucose from the intestine. It is
concluded that the fasting hyperinsulinemia that is characteristic of VMH
animals is under vagal control and that its elimination does not prevent
the development of obesity.
