Evidence for presynaptic cholinergic receptors on dopaminergic terminals: degeneration studies with 6-hydroxydopamine.

Intraventricular injections of 6-hydroxydopamine (6-OHDA) caused a significant decrease in the tyrosine hydroxylase of striatal synaptosomes of rats, without influencing GABA levels. Significant decreases in the muscarinic and nicotinic receptors also occurred in this preparation after 3 days. The receptors were measured by specific binding studies with N-methylatropine and alpha-bungarotoxin respectively. These results indicate that muscarinic and nicotinic receptors are located on the dopaminergic nerve terminals of corpus striatum.