title: Presynaptic adenosine A2 and N-methyl-D-aspartate receptors regulate dopamine synthesis in rat striatal synaptosomes.
abstract: Dopamine synthesis rate and cyclic AMP concentration were measured in synaptosomes prepared from rat striatum. Dopamine synthesis rate was decreased by the addition of either adenosine deaminase or 8-phenyltheophylline, an adenosine receptor blocker, and was increased by the addition of 2-chloroadenosine. The addition of L-glutamate in the absence of adenosine deaminase decreased both dopamine synthesis rate and cyclic AMP concentration; in the presence of adenosine deaminase, glutamate had no effect on basal dopamine synthesis, but enhanced K(+)-stimulated synthesis. Both these effects of glutamate were abolished in Ca2(+)-free medium or in the presence of 2-amino-5-phosphonovalerate, an N-methyl-D-aspartate (NMDA) receptor blocker. In Mg2(+)-free medium with adenosine deaminase, glutamate enhanced both basal and K(+)-stimulated synthesis. These results suggest that dopaminergic terminals have A2 adenosine receptors, whose activation can stimulate dopamine synthesis by a cyclic AMP-dependent mechanism, and NMDA receptors, which modulate dopamine synthesis by a Ca2(+)-dependent mechanism.
authors.affiliation: University Laboratory of Physiology, Oxford, England.
authors.forename: M
authors.initials: M
authors.lastname: Chowdhury
authors.forename: M
authors.initials: M
authors.lastname: Fillenz
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D000243:Adenosine Deaminase / Q000494:pharmacology; D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism* / Q000648:ultrastructure; D003470:Culture Media; D004298:Dopamine / Q000096:biosynthesis*; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D011983:Receptors, Purinergic / Q000502:physiology*; D013569:Synapses / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism*
chemical_list: D003470:Culture Media; D005971:Glutamates; D016194:Receptors, N-Methyl-D-Aspartate; D011983:Receptors, Purinergic; D018698:Glutamic Acid; D000243:Adenosine Deaminase; D000241:Adenosine; D004298:Dopamine