title: Adenosine-dopamine interactions: development of a concept and some comments on therapeutic possibilities.
abstract: This brief review presents a personal perspective on the historical development of the current knowledge about the biologically important concept of functional antagonism between adenosine A2A and dopamine D2 receptors in caudate-putamen, accumbens, and tuberculum olfactorium. In the 1970s, studies of dopamine actions suggested an unexpected role of adenosine. Developments during the next decade substantiated this finding and demonstrated that a subform of adenosine A2 receptors was enriched in the basal ganglia. Cloning of adenosine receptors provided better tools for cellular localization and showed that A2A receptors are closely associated with D2 receptors. Distinct functional interactions at several levels were discovered, and there is now strong evidence that A2A receptors are tonically active and modified by dopamine acting at D2 receptors. Development of selective antagonists and knockout mice have highlighted the potential usefulness of A2A antagonists in decreasing symptoms and progression of Parkinson's disease-something that has also been vindicated by careful epidemiologic studies. There are issues of efficacy and potential side effects that need to be resolved, but the future looks bright.
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden. Bertil.Fredholm@fyfa.ki.se
authors.forename: Bertil B
authors.initials: BB
authors.lastname: Fredholm
authors.forename: Per
authors.initials: P
authors.lastname: Svenningsson
mesh_terms: D000241:Adenosine / Q000378:metabolism*; D058917:Adenosine A2 Receptor Antagonists; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D006801:Humans; D051379:Mice; D009419:Nerve Tissue Proteins; D010300:Parkinson Disease / Q000188:drug therapy / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011743:Pyrimidines / Q000494:pharmacology; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014230:Triazoles / Q000494:pharmacology
chemical_list: C098657:5-amino-7-(2-phenylethyl)-2-(2-furyl)pyrazolo(4,3-e)-1,2,4-triazolo(1,5-c)pyrimidine; D058917:Adenosine A2 Receptor Antagonists; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D011743:Pyrimidines; D043705:Receptor, Adenosine A2A; D017448:Receptors, Dopamine D2; D014230:Triazoles; D002110:Caffeine; D000241:Adenosine; D004298:Dopamine