Lateralization of aminopeptidase A activity in substantia nigra, striatum and frontal cortex of rats.

Several brain aminopeptidase activities have been reported to be asymmetrical, but no direct correlation with lateralized functions has been proposed. Cholecystokinin (CCK) coexists with dopamine (DA) in the nigrostriatal system, which is involved in lateralized motor behaviors. Because aminopeptidase A activity is probably responsible for the hydrolysis of CCK, we studied the left-right distribution of glutamate- (GluAP) and aspartate-aminopeptidase (AspAP) activities in their soluble (Sol) and membrane-bound (M-B) forms in the substantia nigra, striatum and cortex of rats. Although there was a highly significant predominance of the left side in the substantia nigra and striatum for Sol GluAP and M-B AspAP respectively, in the frontal cortex predominance was on the right side for M-B AspAP. These results suggest a relationship between aminopeptidase A activity and lateralized nigro-striato-cortical functions involving CCK.