Cholinergic mechanisms involved in head-shaking of infant rats.

Central cholinergic mechanisms involved in D-amphetamine induced head-shaking (H-S) were explored in 9-day-old albino rats using anticholinergic, anticholinesterase and cholinomimetic drugs. Scopolamine (5 mg/kg, IP) blocks both spontaneous and D-amphetamine induced H-S. Physostigmine (0.10 mg/kg, IP), but not neostigmine, increases D-amphetamine induced H-S up to 400%. Pilocarpine (1-10 mg/kg, IP) per se induces H-S and strongly potentiates the amphetamine H-S effect. Cholinergic--catecholaminergic interactions in the CNS are discussed in relation to the expression of this motor item.