DIABETIC RATS PREFER GLUCOSE-PAIRED FLAVORS OVER FRUCTOSE-PAIRED FLAVORS

Prior studies indicate that glucose has a more potent postingestive re inforcing effect than fructose. The role of insulin in this effect was examined by comparing sugar-conditioned flavor preferences in normal and streptozotocin-diabetic rats. In Experiment 1, diabetic rats, like normal rats, preferred a cue flavor that had been mixed into 8% gluco se solution over a flavor mixed with 8% fructose. Both taste and posti ngestive properties of glucose may have contributed to this preference . Experiment 2 evaluated postingestive reinforcement by pairing cue fl avors with intragastric infusions of glucose and fructose. Both diabet ics and normals acquired a preference for the flavor paired with intra gastric 16% glucose infusions over the flavor paired with 16% fructose infusions although the preference was somewhat smaller in the diabeti c rats. Taken together, the results indicate that a normal insulin sec retory response to glucose is not required for glucose-conditioned fla vor preferences. The diabetic rats' reduced flavor preference in Exper iment 2 suggests that insulin may play some role in glucose conditioni ng although this may be secondary to alterations in gastrointestinal m otility characteristic of diabetic animals. (C) 1997 Academic Press Li mited.