Synaptosomal dopamine from phenylalanine in brain: effects of some dopaminergic agents.

This report demonstrates for the first time that the synthesis and release responses to some dopaminergic agents may be elicited from that synaptosomal dopamine which may be formed by the hydroxylations of phenylalanine. Amphetamine and Cogentin increased the release of dopamine formed from 14C-phenylalanine in rat caudate nucleus synaptosomal preparation and concomitantly stimulated the synthesis. Amfonelic acid also caused a net release of that dopamine. Reserpine markedly increased the medium level of formed dopamine and at the same time inhibited the synthesis of the amine. Triton X-100 detergent almost completely inhibited the substrate uptake and the formation of dopamine. In conclusion, the results suggest that synaptosomal particles represent an unit capable of synthesizing dopamine from phenylalanine and that the synthesis from this precursor may be under the regulatory control of the particles to some degree.