Adenosine receptor agents and conditioned place preference.

1. The effects of different doses of the adenosine agonists N5-ethylcarboxamido-adenosine (NECA), R-isomer of N6-phenylisopropyladenosine (R-PIA), and N6-cyclohexyladenosine (CHA) or of the antagonists theophylline and 8-phenyltheophylline (8-PT) on conditioned place preference (CPP) have been studied. 2. The results show that R-PIA and CHA induced conditioned place aversion (CPA) whereas NECA induced conditioned place preference (CPP). 3. Low doses of theophylline elicit CPP, but high doses of the drug induced CPA. 8-PT also produced the CPP. 4. The responses of R-PIA and CHA but not NECA was decreased by theophylline and 8-PT administration. 5. It is concluded that the induction of CPP an CPA by adenosine antagonsists may be mediated by different adenosine receptors.