Upregulation of striatal adenosine A2A receptor mRNA in 6-hydroxydopamine-lesioned rats intermittently treated with L-DOPA.

To determine whether the adenosine A2A receptor might play a role in L-DOPA-induced dyskinesia in Parkinson's disease, we analyzed changes in the expression of A2A receptor mRNA in response to intermittent treatment with L-DOPA in rats with dopaminergic denervation by 6-hydroxydopamine (OHDA) infusion into the medial forebrain bundle. Intermittent treatment with L-DOPA increased A2A receptor mRNA levels in the dopamine-depleted striatum of 6-OHDA-lesioned rats exhibiting behavioral sensitization to L-DOPA. These results suggest that A2A receptor activation is associated with the development of motor complications induced by L-DOPA treatment.