BRAIN SIGMA-RECEPTORS LABELED BY [H-3] NEMONAPRIDE

Binding of [H-3]nemonapride and [H-3]raclopride was examined in the br ain areas of three species (rat, cow and human). The results indicated that [H-3]nemonapride binding is inhibited by selective a receptor li gands in frontal cortex, striatum and cerebellum. Only the striatum sh owed significant dopaminergic sites as defined by sulpiride. Use of th e subtraction method of [H-3]nemonapride minus [H-3]raclopride binding as a measure of D-4 dopamine receptor binding may, therefore, also in clude a sigma receptor component.