Inhibition of fatty acid β-oxidation attenuates the reinforcing effects and palatability to fat

Objective We investigated the effects of the energy signal on the reinforcing effects and palatability to fat in mice. Methods To examine the effects of postingestive energy signal, mice were injected with 400 μmol/kg body mass of mercaptoacetate, a β-oxidation blocker or with saline (control group). Reinforcing effects and palatability response were examined with the conditioned place preference and one-bottle tests, respectively. Results In conditioned place preference tests, the mercaptoacetate group exhibited reinforcing effects when offered a 40% sucrose solution, which is not metabolized by the β-oxidation pathway, but not when offered 100% corn oil. The control group exhibited reinforcing effects when offered the sucrose solution and when offered corn oil. In one-bottle tests, the control group exhibited palatability to corn oil, but the mercaptoacetate group did not. Consumption of sucrose solution was identical for both groups. Conclusions These results suggest that postingestive energy signal influences the reinforcing effects and palatability of fat.