Influence of muscarinic receptor modulators on interacerebroventricular injection of arachydonylcyclopropylamide induced antinociception in mice.

The interaction between antinociception induced by CB1 agonist and muscarinic receptor modulators has not been studied yet. In the present study, the effect of pilocarpine (a muscarinic agonist) and atropine (a muscarinic antagonist) on arachidonylcyclopropylamide (ACPA, a CB1 agonist) induced antinociception was studied in mice. In this study the antinociceptive effect of intracerebroventricular administration of ACPA (0.001-2 μg/mice) or intraperitoneal injection of pilocarpine (2.5-20mg/kg) or atropine (1 and 5mg/kg) were studied individually. Then the effect of co-administration of pilocarine (2.5mg/kg) or atropine (5mg/kg) and ACPA (0.001-2 μg/mice) were studied as well. ACPA and pilocarpine induced antinociception in mice but atropine did not. Pilocarpine potentiated but atropine antagonized the antinociceptive effect of ACPA. It is concluded that ACPA induced antinociception is influenced by muscarinic receptor modulators in mice.