Prochlorperazine Induces Central Antinociception Mediated By The Muscarinic System

The antinociceptive effect of the D-2 antagonist prochlorperazine was examined in the mouse hot-plate and abdominal constriction tests. Prochlorperazine (1-2 mg kg(-1) s.c./i.p.) produced an increase of the pain threshold in the mouse hot-plate test. The antinociception produced by prochlorperazine was prevented by the D-2 selective agonist quinpirole, the unselective muscarinic antagonist atropine, the M-1 selective antagonist pirenzepine, and by the choline uptake inhibitor hemicholinium-3 hydrobromide (HC-3). Moreover, prochlorperazine antinociception was abolished by pretreatment with an aODN against the M-1 receptor subtype, administered at the dose of 2 nmol per single i.c.v. injection. By contrast the analgesic effect of prochlorperazine was not prevented by the opioid antagonist naloxone and the GABA(B) antagonist CGP-35348. Prochlorperazine also elicited a dose-dependent increase in ACh release from rat cerebral cortex. In the antinociceptive dose-range, prochlorperazine did not impair mouse performance evaluated by the rota-rod and hole-board tests. On the basis of the above data, it can be postulated that prochlorperazine exerted an antinociceptive effect mediated by a central cholinergic mechanism. (C) 2004 Elsevier Ltd. All rights reserved.