The effect of ventromedial hypothalamic lesions on metabolism and insulin secretion in rats on a controlled feeding regimen.

The metabolic effect of ventromedial hypothalamic (VMH) lesions, which are known to cause hyperphagia and obesity, has been studied in rats kept on a controlled light and food regimen. The animals were sacrificed at 4 different times during the second postoperative day. A feeding-induced hypersecretion of insulin was found to the VMH-lesioned animals. It was accompanied by a marked hypoglycemia as compared to the control groups during the feeding period. The glycogen content of liver and diaphragm in the lesioned groups is increased as compared to the controls during the same period. The VMH-lesioned animals showed hypertriglyceridemia both in the fed and fasted state, whereas the postabsorptive plasma levels of free fatty acids and glycerol were decreased. An increased level of urea was observed in all lesioned groups. This is in accordance with the demonstrated protein catabolism which follows VMH lesions.