Modulation of striatal dopaminergic function by local injection of 5'-N-ethylcarboxamide adenosine.

Rats rotated to the left when 5'-N-ethylcarboxamide adenosine (NECA) was injected into the left caudate nucleus and apomorphine was administered subcutaneously. The combination of NECA and apomorphine was more potent than L-(phenylisopropyl)adenosine and apomorphine in eliciting rotation, suggesting the involvement of adenosine receptors of the Ra type. The response was reduced when 2',5'-dideoxyadenosine was injected along with NECA into the caudate nucleus or when theorphylline was given intraperitoneally. Higher doses of apomorphine elicited a self-mutilatory response after the injection of NECA into the caudate nucleus. These results suggest that adenosine may be involved in the modulation of dopaminergic function in the striatum.