Microinjections of acetylcholine and eserine localised within the substantia nigra of the rat elicited a dose-dependent increase in feeding, but not drinking when both food and water were freely available. When required to perform an operant response for food, microinjections of carbachol into substantia nigra caused a dose-dependant increase in lever pressing for food (FR5). High doses of carbachol (1.0 and 5.0 μ1) elicited a behavioural stereotypy characterised by chewing, gnawing and biting. A significant negative correlation was found between the effectiveness of cholinergic stimulation and the distance from the site of highest feeding which was in the pars compacta region of substantia nigra. These data suggest a functional role for acetylcholine within substantia nigra and provide indirect support for the concept of an interaction between cholinergic and dopaminergic neurons within this structure.
- substantia nigra