Release of acetylcholinesterase and aminopeptidase in vivo following infusion of amphetamine into the substantia nigra.

Push-pull cannulae were implanted acutely in both substantiae nigrae and both caudate nuclei of the rabbit under urethane anesthesia. Direct infusion of d-amphetamine (10(-6) M) to one substantia nigra evoked a release of acetylcholinesterase and aminopeptidase not only locally, but also from the contralateral caudate nucleus and substantia nigra. The spontaneous release of acetylcholinesterase was reduced in the ipsilateral caudate nucleus. Gel electrophoresis showed that only one molecular form of each enzyme was released. Since the electrophoretic mobilities of these two enzymic activities were different, the released acetylcholinesterase and aminopeptidase belong to separate molecular species. As amphetamine is known to modify dopamine metabolism the evoked release of these two enzymes is probably related to the dopamine-containing nigrostriatal system.