title: Glucose-conditioned flavor preference learning requires co-activation of NMDA and dopamine D1-like receptors within the amygdala.
abstract: The role of amygdala (AMY) NMDA receptor signaling and its interaction with dopamine D1-like receptor signaling in glucose-mediated flavor preference learning was investigated. In Experiment 1, rats were trained with a flavor (CS+) paired with intragastric (IG) 8% glucose infusions and a different flavor (CS-) paired with IG water infusions. In the two-bottle tests (Expression), bilateral intra-AMY injections of the NMDA receptor antagonist, AP5 (0, 5 and 10 nmol/brain), did not block the CS+ preference. In Experiment 2, new rats received intra-AMY injections of either vehicle or AP5 (10 nmol), prior to training sessions with CS+/IG glucose and CS-/IG water. In the two-bottle tests without drug treatment, AP5 rats failed to prefer the CS+ flavor (50%). In Experiments 3, new rats were trained as in Experiment 2 except that, during training, half the rats received AP5 injections (5 nmol) in one side of the AMY and SCH23390 (D1-like receptor antagonist, 6 nmol), in the contralateral AMY (Drug/Drug group). The remaining rats received vehicle injections in one side of the AMY and either AP5 (5 nmol) or SCH23390 (6 nmol) in the contralateral AMY (Drug/Vehicle group). The two-bottle choice tests without drug treatment revealed that, unlike the Drug/Vehicle group (85%), the Drug/Drug group failed to prefer the CS+ flavor (50%). These results reveal an essential role for AMY NMDA receptor activation in the acquisition of flavor preference learning induced by the post-oral reinforcing properties of glucose and demonstrate that such learning is based on co-activation of NMDA and DA D1 receptors within this forebrain structure.
authors.affiliation: Department of Psychology, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA. Electronic address: ktouzani@brooklyn.cuny.edu.
authors.forename: Khalid
authors.initials: K
authors.lastname: Touzani
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Bodnar
authors.forename: Anthony
authors.initials: A
authors.lastname: Sclafani
mesh_terms: D000679:Amygdala / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology; D005518:Food Preferences / Q000187:drug effects* / Q000502:physiology; D005947:Glucose / Q000494:pharmacology*; D007858:Learning / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D013649:Taste / Q000187:drug effects / Q000502:physiology
chemical_list: D017447:Receptors, Dopamine D1; D016194:Receptors, N-Methyl-D-Aspartate; D005947:Glucose
keywords: 2-amino-5-phosphonopentanoate; AMY; AP5; BLA; CS; Carbohydrate; CeA; Conditioning; DA; Forebrain; IG; LTP; Learning; Rat; SCH23390; US; amygdala; basolateral amygdale; central amygdale; conditioned stimulus; dopamine; intragastric; long-term potentiation; unconditioned stimulus