Alcohol intake of P rats is regulated by muscarinic receptors in the pedunculopontine nucleus and VTA.
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.
Katner
S N
SN
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis 46202, USA.
McBride
W J
WJ
Lumeng
L
L
Li
T K
TK
Murphy
J M
JM
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*
D018721:Muscarinic Agonists; D002217:Carbachol; D012601:Scopolamine