title: Alcohol intake of P rats is regulated by muscarinic receptors in the pedunculopontine nucleus and VTA.
abstract: Experiments were conducted to determine whether muscarinic receptors within the pedunculopontine nucleus (PPN) and ventral tegmental area (VTA) are involved in regulating ethanol drinking behavior in the alcohol-preferring P line of rats. Female P rats were given limited access (2 h/day) to 10% (v/v) ethanol and 0.0125% (g/100 ml) saccharin solutions. Food was available ad libitum. Cholinergic agents were microinjected unilaterally into the PPN or VTA immediately prior to ethanol access. Intra-PPN carbachol (1-4 microg/0.5 microl), which can inhibit cholinergic neuronal activity within the PPN, decreased ethanol (70% decrease at the highest dose; p < 0.05) and saccharin (90% decrease at the highest dose; p < 0.05) intake in a dose-dependent manner within the first 30 min. Intra-PPN scopolamine (5-15 microg/0.5 microl), which can stimulate cholinergic neuronal activity within the PPN, decreased ethanol intake in a dose-dependent manner within the first 30 min (65% decrease at the highest dose; p < 0.05) without reducing saccharin intake. Intra-VTA methylscopolamine (1-10 microg/0.5 microl), a muscarinic antagonist, significantly (p < 0.05) reduced ethanol (60% decrease at the highest dose) and saccharin (50% decrease at the highest dose) intakes during the 2-h access period. Intra-VTA carbachol, a cholinergic agonist (1 and 2 microg/0.5 microl) decreased ethanol consumption in a dose-dependent manner within the first 60 min (50% decrease at the highest dose) without reducing saccharin intake. Overall, these results support an involvement of the cholinergic PPN-VTA system in regulating alcohol drinking and general consummatory behaviors of the P line of rats.
authors.affiliation: Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis 46202, USA.
authors.forename: S N
authors.initials: SN
authors.lastname: Katner
authors.forename: W J
authors.initials: WJ
authors.lastname: McBride
authors.forename: L
authors.initials: L
authors.lastname: Lumeng
authors.forename: T K
authors.initials: TK
authors.lastname: Li
authors.forename: J M
authors.initials: JM
authors.lastname: Murphy
mesh_terms: D000428:Alcohol Drinking; D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects; D004435:Eating / Q000187:drug effects; D005260:Female; D008845:Microinjections; D018721:Muscarinic Agonists / Q000494:pharmacology*; D011149:Pons / Q000187:drug effects*; D051381:Rats; D012601:Scopolamine / Q000494:pharmacology*; D013681:Tegmentum Mesencephali / Q000187:drug effects*
chemical_list: D018721:Muscarinic Agonists; D002217:Carbachol; D012601:Scopolamine