title: Ghrelin and nicotine stimulate equally the dopamine release in the rat amygdala.
abstract: The orexigenic peptide ghrelin plays a prominent role in the regulation of energy balance and in the mediation of reward processes and reinforcement for addictive drugs, such as nicotine. Nicotine is the principal psychoactive component in tobacco, which is responsible for addiction and relapse of smokers. Ghrelin and nicotine activates the mesolimbicocortical dopaminergic pathways via growth hormone secretagogue receptors (GHS-R1A) and nicotinic acetylcholine receptors (nAchR), respectively, resulting in the release of dopamine in the nucleus accumbens, the amygdala and the prefrontal cortex. In the present study an in vitro superfusion of rat amygdalar slices was performed in order to investigate the direct action of ghrelin and nicotine on the amygdalar dopamine release. Ghrelin increased significantly the dopamine release from the rat amygdala following electrical stimulation. This effect was inhibited by both the selective GHS-R1A antagonist GHRP-6 and the selective nAchR antagonist mecamylamine. Under the same conditions, nicotine also increased significantly the dopamine release from the rat amygdala. This effect was antagonized by mecamylamine, but not by GHRP-6. Co-administration of ghrelin and nicotine induced a similar increase of amygdalar dopamine release. This stimulatory effect was partially reversed by both GHRP-6 and mecamylamine. The present results demonstrate that both ghrelin and nicotine stimulates directly the dopamine release in the amygdala, an important dopaminergic target area of the mesolimbicocortical pathway.
authors.affiliation: Department of Pathophysiology, Faculty of Medicine, University of Szeged, Semmelweis Str. 1, Szeged, 6725, Hungary.
authors.forename: Miklós
authors.initials: M
authors.lastname: Palotai
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Bagosi
authors.forename: Miklós
authors.initials: M
authors.lastname: Jászberényi
authors.forename: Krisztina
authors.initials: K
authors.lastname: Csabafi
authors.forename: Roberta
authors.initials: R
authors.lastname: Dochnal
authors.forename: Máté
authors.initials: M
authors.lastname: Manczinger
authors.forename: Gyula
authors.initials: G
authors.lastname: Telegdy
authors.forename: Gyula
authors.initials: G
authors.lastname: Szabó
mesh_terms: D000679:Amygdala / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D054439:Ghrelin / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008464:Mecamylamine; D009538:Nicotine / Q000494:pharmacology*; D009842:Oligopeptides / Q000494:pharmacology; D017397:Prefrontal Cortex / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D054440:Receptors, Ghrelin / Q000187:drug effects; D011978:Receptors, Nicotinic / Q000187:drug effects
chemical_list: D054439:Ghrelin; D009842:Oligopeptides; D054440:Receptors, Ghrelin; D011978:Receptors, Nicotinic; C041048:growth hormone releasing hexapeptide; D008464:Mecamylamine; D009538:Nicotine; D004298:Dopamine