title: Identification of a dopamine receptor-mediated opiate reward memory switch in the basolateral amygdala-nucleus accumbens circuit.
abstract: The basolateral amygdala (BLA), ventral tegmental area (VTA), and nucleus accumbens (NAc) play central roles in the processing of opiate-related associative reward learning and memory. The BLA receives innervation from dopaminergic fibers originating in the VTA, and both dopamine (DA) D1 and D2 receptors are expressed in this region. Using a combination of in vivo single-unit extracellular recording in the NAc combined with behavioral pharmacology studies, we have identified a double dissociation in the functional roles of DA D1 versus D2 receptor transmission in the BLA, which depends on opiate exposure state; thus, in previously opiate-naive rats, blockade of intra-BLA D1, but not D2, receptor transmission blocked the acquisition of associative opiate reward memory, measured in an unbiased conditioned place preference procedure. In direct contrast, in rats made opiate dependent and conditioned in a state of withdrawal, intra-BLA D2, but not D1, receptor blockade blocked opiate reward encoding. This functional switch was dependent on cAMP signaling as comodulation of intra-BLA cAMP levels reversed or replicated the functional effects of intra-BLA D1 or D2 transmission during opiate reward processing. Single-unit in vivo extracellular recordings performed in neurons of the NAc confirmed an opiate-state-dependent role for BLA D1/D2 transmission in NAc neuronal response patterns to morphine. Our results characterize and identify a novel opiate addiction switching mechanism directly in the BLA that can control the processing of opiate reward information as a direct function of opiate exposure state via D1 or D2 receptor signaling substrates.
authors.affiliation: Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Lintas
authors.forename: Ning
authors.initials: N
authors.lastname: Chi
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Lauzon
authors.forename: Stephanie F
authors.initials: SF
authors.lastname: Bishop
authors.forename: Shervin
authors.initials: S
authors.lastname: Gholizadeh
authors.forename: Ninglei
authors.initials: N
authors.lastname: Sun
authors.forename: Huibing
authors.initials: H
authors.lastname: Tan
authors.forename: Steven R
authors.initials: SR
authors.lastname: Laviolette
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000701:Analgesics, Opioid / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D004195:Disease Models, Animal; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D009020:Morphine / Q000494:pharmacology; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology*; D009293:Opioid-Related Disorders / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000502:physiology*; D011957:Receptors, Opioid / Q000378:metabolism*; D012201:Reward; D012457:Salicylamides / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D000701:Analgesics, Opioid; D001552:Benzazepines; D018492:Dopamine Antagonists; D047428:Protein Kinase Inhibitors; D011954:Receptors, Dopamine; D011957:Receptors, Opioid; C534628:SCH 23390; D012457:Salicylamides; D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D009020:Morphine; D000242:Cyclic AMP; C045989:eticlopride