THE ROLE OF GASTRIC AND POSTGASTRIC SITES IN GLUCOSE-CONDITIONED FLAVOR PREFERENCES IN RATS

Two experiments examined the role of gastric and postgastric contribut ions in the development of flavor preferences in rats. During training trials, food-deprived rats consumed, on alternate days, a cue flavor paired with glucose infusions and another flavor paired with water inf usions. Preferences were assessed in choice tests between the two cue flavors without infusions. The first experiment compared preferences c onditioned to a flavor paired with intraduodenal (ID) glucose infusion s to those paired with intragastric (IG) infusions. ID glucose-conditi oned preferences were as strong as that of IG glucose. The second expe riment examined whether the actions of glucose in the stomach alone we re sufficient to condition flavor preferences. Glucose infusions were restricted to the stomach with an inflated pyloric cuff and then remov ed at the end of 30-min training sessions before the cuff was deflated . Rats trained with this procedure did not develop a reliable flavor p reference. Flavor preferences were obtained, however, when the cuff wa s inflated for 30 min after the end of the daily training sessions, or when the cuff was inflated during the training sessions but then defl ated without removing the infused glucose. Both of these procedures al lowed at least some of the infused glucose to empty into the intestine . Taken together, the results indicate that information from the stoma ch is neither necessary nor sufficient to produce glucose-conditioned flavor preferences. Such preferences are reinforced by the intestinal and/or postabsorptive actions of glucose. Copyright (C) 1997 Elsevier Science Inc.