Control of food intake by fatty acid oxidation

The role of fatty acid oxidation in the control of food intake was studied using mercaptoacetate (MA), an inhibitor of fatty acid oxidation. Food intake, plasma free fatty acids (FFA) and ketone bodies, and blood glucose were measured. Rats were fed either a low-fat (LF, 3.33% fat) or a medium-fat (MF, 18% fat) diet. At the onset of the dark phase of the lighting cycle, MA did not affect food intake in LF rats but increased it 74% in MF rats in comparison to control. Four hours after the injection the effect of MA on food intake disappeared. In the middle of the bright phase of the lighting cycle, MA increased food intake in MF rats approximately 120% up to 6 h postinjection. After MA, plasma FFA concentration was elevated, and plasma 3-hydroxybutyrate concentration was lowered, indicating that fatty acid oxidation had been successfully reduced. MA did not affect blood glucose. These results indicate fatty acid oxidation is involved in the control of food intake, at least when the dietary fat level is relatively high.