The effects of scopolamine and pilocarpine upon the aversive threshold of the rat

Abstract

The analgesic potency of scopolamine hydrobromide (0.125, 0.250, 0.50, 1.0, 2.0 mg/kg) and pilocarpine nitrate (1.25, 2.50, 5.0, 10.0 mg/kg) were measured in the rat using the spatial preference technique. Only pilocarpine nitrate in doses at or above 2.50 mg/kg significantly raised the aversive threshold. These data were interpreted to indicate that cholinergic systems may be involved in the production of analgesia in the rat. The present results may be useful in interpreting the behavioral effects of cholinergic drugs administered to animals that are under the control of aversive schedules of reinforcement.