title: Serotonin3 antagonists block aversion to saccharin in an amino acid-imbalanced diet.
abstract: Conditioned taste aversion presumably plays a role in the anorectic responses to amino acid-imbalanced diets that induce acute amino acid deficiency. The serotonin3 (5-HT3) receptor antagonists, tropisetron (Trop), MDL-72222 (MDL), and ondansetron, increase intake of imbalanced amino acid diets. Therefore, we tested whether 5-HT3 receptor antagonists would block an aversion to powdered saccharin after it was included in an amino acid-imbalanced diet. Rats were given an intraperitoneal injection of Trop, MDL, or vehicle (Veh), just before introducing one of four diets: imbalanced amino acid diet +/- saccharin (Imb or ImbSac) or a balanced (corrected) diet +/- saccharin (Cor or CorSac). Subsequent aversion to saccharin was shown in preference tests using Cor and CorSac. Saccharin preference was significantly decreased (8.3% on test day 1) in the Veh/ImbSac group, but the Trop/ImbSac group's saccharin preference (57.8%) was similar to controls (49.6-70.3%); MDL also blocked the aversion to saccharin after ImbSac. This confirms previous reports of conditioned taste aversions with amino acid limitation and suggests a role for the 5-HT3 receptor in the development of these aversions.
authors.affiliation: Department of Molecular Biosciences and Anatomy, School of Veterinary Medicine, University of California, Davis 95616, USA.
authors.forename: V R
authors.initials: VR
authors.lastname: Terry-Nathan
authors.forename: D W
authors.initials: DW
authors.lastname: Gietzen
authors.forename: Q R
authors.initials: QR
authors.lastname: Rogers
mesh_terms: D000596:Amino Acids / Q000008:administration & dosage*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D003213:Conditioning, Psychological; D004032:Diet; D004435:Eating; D005518:Food Preferences; D007211:Indoles / Q000494:pharmacology; D008297:Male; D017294:Ondansetron / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012439:Saccharin; D012702:Serotonin Antagonists / Q000494:pharmacology*; D014326:Tropanes / Q000494:pharmacology; D000077526:Tropisetron
chemical_list: D000596:Amino Acids; D007211:Indoles; D012702:Serotonin Antagonists; D014326:Tropanes; D017294:Ondansetron; D000077526:Tropisetron; D012439:Saccharin; C042253:bemesetron