Xanthines alter behavior maintained by intracranial electrical stimulation and an operant schedule.

Caffeine and related alkylxanthines are widely used for recreation and therapeutic effects. In behavioral studies, both response rate-enhancing and attenuating effects have been described, depending upon the dose and behavioral measure used. Intracranial self-stimulation (ICSS) and differential reinforcement of low rates of responding (DRL) were assessed after rats were administered one of a range of doses of caffeine or aminophylline. These measures were chosen because of their demonstrated sensitivity to psychotropic drugs and the potential for comparing the alkylxanthine data to the extensive literature of amphetamine effects on ICSS and DRL behavior. Caffeine and aminophylline elicited dose- and drug-dependent changes in ICSS responding, and increased response rates and decreased reinforcements on the DRL schedule. These behavioral results are discussed with reference to alkylxanthine interactions with adenosine receptors.