Dopamine D2 receptor-mediated modulation of adenosine A2A receptor agonist binding within the A2AR/D2R oligomer framework

Abstract

The molecular interaction between adenosine A(2A) and dopamine D-2 receptors (A(2A)Rs and D(2)Rs, respectively) within an oligomeric complex has been postulated to play a pivotal role in the adenosine-dopamine interplay in the central nervous system, in both normal and pathological conditions (e.g. Parkinson's disease). While the effects of A(2A)R challenge on D2R functioning have been largely studied, the reverse condition is still unexplored, a fact that might have impact in therapeutics. Here, we aimed to examine in a real-time mode the D2R-mediated allosteric modulation of A(2A)R binding when an A(2A)R/D2R oligomer is established. Thus, we synthesized fluorescent A(2A)R agonists and evaluated, by means of a flow cytometry homogeneous no-wash assay and a real-time fluorescence resonance energy transfer (FRET)-based approach, the effects on A(2A)R binding of distinct antiparkinsonian drugs in current clinical use (i.e. pramipexole, rotigotine and apomorphine). Our results provided evidence for the existence of a differential D2R-mediated negative allosteric modulation on A(2A)R agonist binding that was oligomer-formation dependent, and with apomorphine being the best antiparkinsonian drug attenuating A(2A)R agonist binding. Overall, the here-developed methods were found valid to explore the ability of drugs acting on D(2)Rs to modulate A(2A)R binding, thus serving to facilitate the preliminary selection of D2R-like candidate drugs in the management of Parkinson's disease. (c) 2013 Elsevier Ltd. All rights reserved.