title: Post-oral sugar detection rapidly and chemospecifically modulates taste-guided behavior.
abstract: Several recent studies have shown that post-oral sugar sensing rapidly stimulates ingestion. Here, we explored the specificity with which early-phase post-oral sugar sensing influenced ingestive motivation. Inexperiment 1, rats were trained to associate the consumption of 0.3 M sucrose with injections of LiCl (3.0 meq/kg ip, conditioned taste aversion) or given equivalent exposures to the stimuli, but in an unpaired fashion. Then, all rats were subjected to two brief-access tests to assess appetitive and consummatory responses to the taste properties of sucrose (0.01-1.0 M), 0.12 M NaCl, and dH2O (in 10-s trials in randomized blocks). Intraduodenal infusions of either 0.3 M sucrose or equiosmolar 0.15 M NaCl (3.0 ml) were administered, beginning just before each test. For unpaired rats, intraduodenal sucrose specifically enhanced licking for 0.03-1.0 M sucrose, with no effect on trial initiation, relative to intraduodenal NaCl. Rats with an aversion to sucrose suppressed licking responses to sucrose in a concentration-dependent manner, as expected, but the intraduodenal sucrose preload did not appear to further influence licking responses; instead, intraduodenal sucrose attenuated trial initiation. Using a serial taste reactivity (TR) paradigm, however,experiment 2demonstrated that intraduodenal sucrose preloads suppressed ingestive oromotor responses to intraorally delivered sucrose in rats with a sucrose aversion. Finally,experiment 3showed that intraduodenal sucrose preloads enhanced preferential licking to some representative tastants tested (sucrose, Polycose, and Intralipid), but not others (NaCl, quinine). Together, the results suggest that the early phase-reinforcing efficacy of post-oral sugar is dependent on the sensory and motivational properties of the ingesta.
authors: Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida schier@psy.fsu.edu.
authors: Lindsey A
authors: LA
authors: Schier
authors: Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida.
authors: Alan C
authors: AC
authors: Spector
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001069:Appetite Regulation / Q000502:physiology*; D001362:Avoidance Learning / Q000502:physiology*; D003214:Conditioning, Classical; D019422:Dietary Sucrose / Q000378:metabolism* / Q000494:pharmacology; D004435:Eating / Q000502:physiology*; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D008297:Male; D019518:Postprandial Period / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013649:Taste / Q000502:physiology*; D055697:Taste Perception
chemical_list: D019422:Dietary Sucrose
keywords: chemosensory; gastrointestinal; gustatory system; nutrient sensing; visceral