title: Mesolimbic dopamine drives the diurnal variation in opiate-induced feeding.
abstract: Brain opioid peptides modulate feeding behavior and opiate drugs have powerful orexigenic effects in mammals. Recent studies have shown that opiate-induced eating depends, though not exclusively, on mu-opioid receptors located in the ventral striatum. Here we report that morphine orexigenic effects vary with the time of day according to a biphasic pattern. The effects first increase and then decrease during the light phase, with the peak effect occurring in the middle of this phase. This diurnal profile is shifted toward the dark phase after dopamine deafferentation of the ventral striatum. Consequently, the peak effect of morphine is delayed and occurs just before the dark phase. This finding suggests that mesolimbic dopamine transmission contributes to the neural mechanisms that normally drive the circadian timing of opioid-dependent feeding.
authors.affiliation: Laboratoire de Neuropsychobiologie des Désadaptations, Centre National de la Recherche Scientifique, UMR 5541, Université Victor Segalen Bordeaux 2 146, rue Léo Saignat, BP 31, 33076 Bordeaux Cedex, France. maria.barbano@etud.u-bordeaux2.fr
authors.forename: M Flavia
authors.initials: MF
authors.lastname: Barbano
authors.forename: Luis
authors.initials: L
authors.lastname: Stinus
authors.forename: Martine
authors.initials: M
authors.lastname: Cador
authors.forename: Serge H
authors.initials: SH
authors.lastname: Ahmed
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002940:Circadian Rhythm; D004298:Dopamine / Q000378:metabolism*; D004435:Eating / Q000187:drug effects*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009294:Narcotics / Q000494:pharmacology; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D009833:Olfactory Pathways / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism
chemical_list: D009294:Narcotics; D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D009020:Morphine; D004298:Dopamine