Adenosine A1 receptor blockade mimics caffeine's attenuation of ethanol-induced motor incoordination

The effects of co-administration of caffeine and ethanol were assessed on the motor coordination of rats on the accelerating rotarod (accelerod). Ethanol (2.5 g/kg, orally) decreased motor performance on the accelerod. Co-administration of caffeine (5 and 20 mg/kg, orally) dose-dependently attenuated this ethanol-induced deficit. Caffeine (20 mg/kg, orally) alone did not affect motor performance in the test. As caffeine is a non-selective adenosine receptor antagonist the ability of adenosine A(1) and A(2A) receptor blockade to attenuate ethanol-induced motor incoordination was determined. Pre-treatment with the adenosine A(1) receptor antagonist DPCPX (5 mg/kg, intraperitoneally) attenuated ethanol (2.5 g/kg, orally)-induced motor incoordination. By contrast, prior administration of the adenosine A(2A) selective antagonist SCH 58261 (10 mg/kg intraperitoneally) had no effect on the ethanol-induced motor deficit. These data demonstrate that adenosine A(1) receptor blockade mimics the inhibitory action of caffeine on ethanol-induced motor incorordination, and may contribute to the ability of caffeine to offset the acute intoxicating actions of ethanol.