M1 receptor activation is a requirement for arecoline analgesia

Arecoline, a drug obtained from the Areca Catechu L., induced a dose-dependent antinociception (0.3-1 mg kg(-1) i.p.) which was prevented by the muscarinic antagonists pirenzepine (0.1 mug per mouse i.c.v.) and S-(-)-ET-126 (0.01 mug per mouse i.c.v.). A dose-dependent inhibition of the antinociception induced by arecoline was observed after inactivation of the M, gene by an antisense oligodeoxyribonucleotide (aODN). This effect was detected 24 h after the last i.c.v. injection of aODN. These results indicate that arecoline antinociception is mediated by the activation of central M, muscarinic receptors. (C). 2001 Editions scientifiques et medicales Elsevier SAS.