Interaction between dopamine and adenosine A(2A) receptors as a basis for the treatment of Parkinson's disease

The adenosine A(2A) receptor antagonist SCH 58261 increases the turning beh aviour induced by L-dopa in unilaterally 6-hydroxydopamine (6-OHDA)-lesione d rats. In this study vie have evaluated the effect of a chronic intermitte nt administration of L-dopa or SCH 58261 plus L-dopa on turning behaviour. Chronic intermittent administration of SCH 58261 plus L-dopa produced a sta ble turning behaviour during the course of the treatment, whereas L-dopa al one produced a progressive increase in turning behaviour. Moreover, repeate d administration of SCH 58261 failed to produce tolerance to its ability to potentiate L-dopa-induced turning behaviour. The results indicate that SCH 58261 is effective after chronic administration and suggest that SCH 58261 plus L-dopa, differently from L-dopa alone, does not produce alterations i n motor responses during the course of the treatment.