Dopamine and acetylcholine release in thalamus of non-parkinsonian and parkinsonian subjects.

A study of neurotransmitter release has been performed on human brain biopsies obtained during the course of a therapeutic neurosurgical procedure. The electrically evoked-release of 3H-dopamine and 3H-acetylcholine was studied on slices from the thalamus of two parkinsonian and two non-parkinsonian subjects. Electrical stimulation of the non-parkinsonian thalamus increased the dopamine release but had no effect on acetylcholine release. This characteristic response had been previously observed in the normal rat thalamus. In contrast, the parkinsonian thalamus responded with a sharp increase in acetylcholine release without concomitant increase in dopamine release indicating the possible existence of an inhibitory control effect action of dopamine on acetylcholine release as seen in rat striatum.