Release of Feeding by the Sweet Taste in Rats: The specificity of Oral Satiety

Abstract

Saccharin intake in hungry rats occurs in discrete “meals”, indicating that a period of saccharin drinking produces a temporary “oral satiety”. We show that such satiety does not suppress the intake of solid food (powdered rat chow), of liquid food (milk), or even of a nutritive sweet solution (glucose) unless it is very dilute. Therefore, oral satiety does not reflect the reduction of a generalized hunger state or of a specific carbohydrate hunger. Having drunk one concentration of saccharin to satiety, the rat will resume drinking if offered a higher concentration but not if offered a lower one, even if the lower one is more palatable than the original concentration. Therefore, in the saccharin-satiated rat, the resumption of drinking requires an increase in stimulus intensity, even if it means a decrease in palatability of the solution offered. We suggest that it is gustatory adaptation that terminates a saccharin meal in the hungry rat.