Mazindol and amphetamine as inhibitors of the uptake and releasers of 3H-dopamine by rat striatal synaptosomes.

The effects of mazindol, amphetamine and fenfluramine on uptake and release of 3H-DA by synaptosomes were studied in different systems. In in vitro incubations of 3H-DA with synaptosomes isolated from the caudate nucleus of the rat, mazindol inhibited the uptake of the radioactivity more potently than did amphetamine. When the synaptosomes were isolated from the caudate nuclei of rats treated in vivo with either mazindol or amphetamine, the uptake of 3H-DA during in vitro incuation was lower with synaptosomes of amphetamine-treated rats than with those of mazindol-treated rats. When synaptosomes of untreated rats were prelabelled with 3H-DA and incubated in the presence of amphetamine or of mazindol, amphetamine caused a greater release of radioactivity than did mazindol. Fenfluramine was without activity in all these systems. In spite of the quantitative differences, both amphetamine and mazindol appear to have similar effects on uptake and release of dopamine, and this may account for their analogous pharmacological profile.