CONDITIONED CONTROL OF INGESTIVE BEHAVIOR BY ACARBOSE-INDUCED INHIBITION OF SUCROSE INGESTION IN THE RAT

Conditioned control of ingestive behavior by Acarbose-induced inhibition of sucrose ingestion in the rat. PHYSIOL BEHAV 55(3) 511-518, 1994.-It has been reported that the addition of Acarbose, a alpha-glucosidase inhibitor, to a carbohydrate solution blocks a preference that otherwise would be displayed for that solution. One interpretation of those results is that the alteration in preference was caused by the diminished postabsorptive nutritive value of the diet due to the inhibition of hydrolysis of the carbohydrates, and, thus, its absorption. An alternative explanation is that the reduction in the preference was a consequence of an accumulation of undigested carbohydrates in the lumen of the intestine. In the studies reported here, designed to investigate this alternative explanation, it was shown that Acarbose added to a flavored 0.3 M sucrose solution reduced the preference for that solution in a two-bottle preference test. An analysis of the licking behavior of rats ingesting flavored 0.3 M sucrose solutions with and without the addition of Acarbose revealed that the presence of Acarbose in the test solution caused a conditioned reduction in the rate of licking the test solution at the beginning of the meal and, as a result, a reduction in intake of the solution. This conditioned control of the rate of licking was rapidly acquired and was easily reversed. It was also shown that Acarbose increased fluid retention in the small intestine, suggesting that the conditioning may have been based on the accumulation of undigested disaccharides in the intestinal lumen rather than on the diminished postabsorptive nutritive value of the ingested sucrose. The accumulation of undigested carbohydrates in the gastrointestinal tract resulting from the presence of Acarbose may play a role in the alterations of conditioned preferences induced by the addition of the compound to test solutions.