Inhibition of 3H-dopamine accumulation in reserpinized and normal rat striatum

The inhibitory potencies of 27 compounds on the accumulation of 3H-dopamine (DA) in synaptosome-rich striatal homogenates of normal and reserpinized rats were determined. It was found that some compounds, e.g. amphetamine derivatives, phenmetrazine, phenethylamine derivatives and tryptamine derivatives were considerably more potent in the reserpinized preparation than in the normal one. Other compounds, e.g. amfonelic acid, mazindol, EXP 561, benztropine, pipradrol, nomifensine, methylphenidate and cocaine had similar potencies in the two preparations. It is suggested that the compounds enhanced by reserpine are more potent as DA releasing agents than as inhibitors of the DA uptake, whereas the compounds in the other group are most potent as uptake inhibitors. Interestingly, these two groups completely agree with the two groups of central stimulatory agents, viz. the amphetamine-like and the methylphenidate-like drugs.