Antinociceptive activity of muscarinomimetic agents

The effect of the agents with muscarinomimetic activity on the nociceptive transmission in the spinal cord was studied in spinal rats. Oxotremorine (5-20 micrograms/kg, i.v.), arecoline (0.25-1.0 mg/kg, i.v.), pilocarpine (5-20 mg/kg, i.v.) and aceclidine (0.25-1.0 mg/kg, i.v.) inhibited the nociceptive flexor reflex induced by intraarterial injection of bradykinin. Muscarinomimetics in the same doses and anticholinesterase agents physostigmine (1-4 micrograms, intrathecally) and galanthamine (25-100 micrograms, intrathecally) inhibited bradykinin-induced bioelectric activity in the spinal ventrolateral tracts. Atropine (1 mg/kg, i.v.) abolished the inhibitory effect of the agents tested on the nociceptive flexor reflex and bioelectric activity.