Effect of neuroleptics and of combinations of d-amphetamine and neuroleptics on 3H-dopamine uptake by homogenates from rat striatum.

Triperidol was found to be a more potent 3H-dopamine uptake inhibitor than chlorpromazine in homogenates from rat striatum. Inhibition kinetics were competitive for triperidol and non-competitive for chlorpromazine. When drugs were given in vivo, d-amphetamine (10 mg/kg) blocked the 3H-dopamine uptake by about 50% whereas the neuroleptics did not modify the process even at highly sedating doses. Combined treatments with d-amphetamine and neuroleptics showed that only triperidol potentiated the blocking effect of d-amphetamine on 3-H-dopamine uptake. However, such a potentiation was not observed when triperidol and d-amphetamine were simultaneously added in vitro. The results tend to suggest that the postulated actions of neuroleptics on presynaptic sites in the striatum may be more important with the butyrophenone, triperidol than with the phenothiazine, chlorpromazine.