TY - JOUR
T1 - Glucose-conditioned flavor preference learning requires co-activation of NMDA and dopamine D1-like receptors within the amygdala
AU - Touzani, Khalid
AU - Bodnar, Richard J.
AU - Sclafani, Anthony
N1 - Funding Information:
This work was supported by National Institute of Diabetes and Digestive and Kidney Diseases Grant DK071761 .
PY - 2013/11
Y1 - 2013/11
N2 - 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.
AB - 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.
KW - AP5
KW - Carbohydrate
KW - Conditioning
KW - Forebrain
KW - Learning
KW - Rat
KW - SCH23390
UR - http://www.scopus.com/inward/record.url?scp=84882619455&partnerID=8YFLogxK
U2 - 10.1016/j.nlm.2013.07.016
DO - 10.1016/j.nlm.2013.07.016
M3 - Article
C2 - 23887141
AN - SCOPUS:84882619455
SN - 1074-7427
VL - 106
SP - 95
EP - 101
JO - Neurobiology of Learning and Memory
JF - Neurobiology of Learning and Memory
ER -