title: Opioid limbic circuit for reward: interaction between hedonic hotspots of nucleus accumbens and ventral pallidum.
abstract: Mu-opioid stimulation of cubic millimeter hedonic hotspots in either the nucleus accumbens shell (NAc) or the ventral pallidum (VP) amplifies hedonic "liking" reactions to sweetness and appetitive "wanting" for food reward. How do these two NAc-VP hotspots interact? To probe their interaction and limbic circuit properties, we assessed whether opioid activation of one hotspot recruited the other hotspot (neurobiologically) and whether opioid hedonic and incentive motivational amplification by either opioid hotspot required permissive opioid coactivation in the other (behaviorally). We found that NAc and VP hotspots reciprocally modulated Fos expression in each other and that the two hotspots were needed together to enhance sucrose "liking" reactions, essentially cooperating within a single hedonic NAc-VP circuit. In contrast, the NAc hotspot dominated for opioid stimulation of eating and food intake ("wanting"), independent of VP activation. This pattern reveals differences between limbic opioid circuits that control reward "liking" and "wanting" functions.
authors.affiliation: Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109, USA. kyless@umich.edu
authors.forename: Kyle S
authors.initials: KS
authors.lastname: Smith
authors.forename: Kent C
authors.initials: KC
authors.lastname: Berridge
mesh_terms: D000701:Analgesics, Opioid / Q000378:metabolism* / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D004347:Drug Interactions; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / Q000494:pharmacology; D004743:Enkephalin, Leucine / Q000378:metabolism; D005247:Feeding Behavior / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D005917:Globus Pallidus / Q000187:drug effects / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology*; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology*; D016761:Oncogene Proteins v-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D013649:Taste / Q000187:drug effects
chemical_list: D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D016761:Oncogene Proteins v-fos; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009270:Naloxone; D004743:Enkephalin, Leucine