Fat Metabolism in Three Forms of Obesity V. Hepatic Lipogenesis in Vitro

Abstract

Liver slices from fed and fasted animals with genetic, goldthioglucose and hypothalamic obesity and from appropriate controls, were incubated with C14- carboxyl-labeled acetate and resultant C14 incorporation into fat determined. Liver slices from all 3 forms of fed obese animals exhibited greater lipogenesis than their controls when results were expressed both per liver and per g of fat-free tissue. Fasting decreases rates of fat synthesis in the liver of all forms of animals. However, while hepatic lipogenesis rates in goldthioglucose and hypothalamic obese animals are depressed by fasting to the same low values as observed in their non-obese controls, the rates in genetically obese mice, while depressed, remain twice as high as that observed in their controls. These results support the distinction previously suggested between "regulatory" and "metabolic" types of obesity.