Effects of selective vagotomies on knife cut-induced hypothalamic obesity: Differential results on lab chow vs high-fat diets

Abstract

Asymmetrical hypothalamic knife cuts were used to produce obesity in rats fed lab chow pellets. When the brain surgery was accompanied by selective section of the coeliac branch of the abomdinal vagus nerve, only 57% of the expected weight gain was observed. Additional section of the gastric branches of the vagus further reduced the knife cut effects, and complete subdiaphragmatic vagotomy suppressed body weight below control levels. Conversely, all vagotomies that spared the coeliac branch did not by themselves attenuate hypothalamic knife cut obesity. These results suggest that some function(s) under coeliac vagal control are specifically involved in mediating hypothalamic hyperphagia and obesity. When, after 30 days, the rats were switched to high-fat diet, all the knife cut rats overate and became obese (or more obese) irrespective of vagotomy status. This overeating despite vagotomy indicates that the vagus nerves must not be the exclusive mediator of hypothalamic obesity. © 1981.