Consequences of ventromedial hypothalamic lesions on metabolism of perfused rat liver.

Abstract

Metabolism of perfused livers from control and ventromedial hypothalamus (VMH)-lesioned rats has been studied. To eliminate the possibility that observed metabolic abnormalities could be realted to hyperphagia, VMH-lesioned rats were placed on restricted diet matching that of controls. Ten days postoperatively, VMH-lesioned rats had hyperinsulinemia, hypertriglyceridemia, increased blood urea nitrogen levels, together with decreased plasma free fatty acid (FFA) and glucose levels. Insulin release produced in vivo by a glucose load was much higher in VMH-lesioned than in control rats. Perfused livers from VMH-lesioned rats secreted more triglycerides and produced more urea than controls, whereas production of glucose and ketone bodies was reduced. Lipogenesis, newly synthesized triglyceride secretion, and the activity of acetyl-CoA carboxylase and fatty acid synthetase were greatest in livers from VMH-lesioned rats. Fasting abolished hyperinsulinemia and most of these observed metabolic alterations. After treatment with anti-insulin serum, the high rate of lipogenesis observed in livers from VMH-lesioned rats was restored toward normal. It is suggested that hyperinsulinemia may be partly responsible for the metabolic disorders observed in livers from nonhyperphagic VMH-lesioned rats.