Integration of orosensory and postingestive stimuli for the control of excessive fat intake in mice

OBJECTIVES: Long-term preferences for, and reinforcement effects of, undigested fat substitutes were investigated by means of a two-bottle choice test and the conditioned place preference (CPP) test. METHODS: We tested intact corn oil and sorbitol fatty acid esters, which have been developed as non-digestible fat substitutes with low energy (1.5 kcal/g). RESULTS: Palatability of the sorbitol fatty acid esters was similar to corn oil over 30 min in the short-term two-bottle choice test in mice. However, mice did not continue to eat the fat substitute in the long-term two-bottle choice test, which included postprandial feedback effects. Moreover, sorbitol fatty acid ester did not act as a reinforcer in the CPP test. Mice with 0.1 mL of corn oil placed into their stomachs just before conditioning showed reinforcing effects on taking sorbitol fatty acid ester in the CPP test. However, intragastric administration of corn oil alone without stimulation of the oral cavity did not show any such reinforcing effects against corn oil. CONCLUSIONS: These results suggest that the postingestible effects of corn oil are involved in long-term preference and reinforcing effects. (C)Elsevier Science Inc. 2003.