Dissociation of gustatory and weight regulatory responses to quinine following lateral hypothalamic lesions.

In a two-phase experiment, consummatory (Phase 1) and body weight regulation (Phase 2) responses to quinine adulteration of a wet mash diet were measured in rats recovered from bilateral lateral hypothalamic lesions (LH; n = 16) and in unoperated control rats (C; n = 18). In Phase 1, all rats were fed wet mash adulterated with increasing concentrations of quinine sulfate every other day, and fed unadulterated wet mash on the alternate days. Group LH consumed a significantly lower proportion of quinine-adulterated wet mash relative to unadulterated wet mash, displaying a steeper concentration-response function and a lower rejection threshold than did Group C. In Phase 2, Groups LH and C were maintained exclusively on quinine-adulterated mash for 20 days. This procedure caused equivalent weight loss in the two groups. Therefore, an apparent exaggerated aversion to quinine-adulterated food does not appear to contribute abnormally to the weight regulation exhibited by rats with lateral hypothalamic damage.