Pilocarpine, a non-hallucinogenic cholinergic agonist, elicits limb flicking in cats

Abstract

The centrally- and peripherally-acting muscarinic cholinergic agonist pilocarpine (PILO, 0.125-1.0 mg/kg, IP) elicited a significantly increased frequency of occurrence of limb flicking at 0.25-1.0 mg/kg, and significantly increased the frequency of occurrence of other grooming behaviors, in 4-6 cats in the 90 min following its administration. These effects of PILO at 0.5 mg/kg were antagonized by the peripherally-acting antimuscarinic agent, N-methylscopolamine (MESCO, 0.5 mg/kg, IP), when MESCO was administered 15 min before PILO. The same lisuride (LIS, 0.05 mg/kg, IP). These results provide further evidence that a cat behavior model for LSD-like hallucinogens which employs limb flicking and similar grooming behaviors is not specific for hallucinogens; indicate that important "model behaviors" may be elicited by a peripheral mechanism; and show that a peripheral muscarinic cholinergic mechanism is not responsible for LSD- and LIS-elicited limb flicking. The results also suggest that the increased frequency of occurrence of the model behaviors after PILO reflects their function as grooming behaviors, elicited by PILO's intense cholinergic effects, including salivation or sialorrhea and emesis.