Post-ingestive positive controls of ingestive behavior.

Post-ingestive negative controls of ingestive behavior are well characterized. Nutrients act in the gut to inhibit meal size by direct actions on feeding and by conditioning a satiation response to orosensory (flavor) stimuli. Accumulating evidence indicates that there are also post-ingestive positive controls of ingestion that operate by conditioning flavor preference and increased acceptance. In several experiments rats trained to consume a flavored solution paired with intragastric carbohydrate infusions significantly increased their solution intake. Drinking bout size and number, and lick rates and burst size were also increased by carbohydrate infusions. Whether intake is stimulated or inhibited by post-ingestive nutrient actions depends upon several factors, including most notably nutrient concentration. Post-ingestive positive controls need to be incorporated into theoretical models of ingestive behavior. Copyright 2001 Academic Press.