title: Sensitization of neuronal A2A adenosine receptors after persistent D2 dopamine receptor activation.
abstract: Acute activation of Galpha(i/o)-coupled D2 dopamine receptors inhibits A2A adenosine receptor stimulation of adenylate cyclase. This antagonistic interaction between D2 dopamine and A2A adenosine receptors has been well documented; however, the effects of persistent activation of D2 dopamine receptors on subsequent A2A adenosine receptor signaling have not been explored. The present study investigated the effects of short-term (3-h) and long-term (18-h) activation of D2L dopamine receptors on subsequent A2A adenosine receptor stimulation of adenylate cyclase in CAD-D2L and NS20Y-D2L neuroblastoma cells. Short- and long-term activation of D2L dopamine receptors markedly increased 5'-N-methylcarboxamidoadenosine (MECA)-stimulated cyclic AMP accumulation 1.4-fold and 1.7-fold, respectively. D2L receptor-induced sensitization of A2A-stimulated cyclic AMP accumulation was blocked by the D2 antagonist spiperone and pertussis toxin pretreatment. In addition, persistent activation of A2A adenosine receptors resulted in 50% desensitization of subsequent MECA-stimulated cyclic AMP accumulation; however, MECA-induced desensitization of A2A adenosine receptors did not prevent completely quinpirole-induced sensitization of adenylate cyclase. These studies revealed a novel mode of regulation between D2L dopamine and A2A adenosine receptors and suggest a cooperative interaction in the regulation of cyclic AMP signaling.
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Vortherms
authors.forename: Val J
authors.initials: VJ
authors.lastname: Watts
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism; D018491:Dopamine Agonists / Q000494:pharmacology; D006801:Humans; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D018491:Dopamine Agonists; D043705:Receptor, Adenosine A2A; D017448:Receptors, Dopamine D2; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D004298:Dopamine