The activation of adenosine A1 receptors is important in protecting against ischemic brain injury.Electroacupuncture (EA) pretreatment has been shown to mitigate ischemic brain insult.The aim of this study was to test whether the adenosine A1 receptor mediates EA pretreatment-induced neuroprotection against ischemic brain injury induced by middle cerebral arterial occlusion (MCAO) in rats.We first evaluated the effect of 30 min of EA pretreatment at the Baihui acupoint on extracellular adenosine triphosphate (ATP) and adenosine levels in the cerebral cortex of native rats.The levels of ATP and adenosine were measured using high-performance liquid chromatography at 0,15,30,60,120, and 150 min after EA pretreatment.After EA treatment, we found that ATP and adenosine levels peaked in the cerebral cortex at 15 and 120 min, respectively.Based on these findings, we further examined the effect of 15 or 120 min of EA treatment on ischemic brain injury in the rat MCAO model.We found that at 24 h after reperfusion, EA treatment for 120 min (concurrent with peak adenosine levels) but not for 15 min (concurrent with peak ATP levels) significantly reduced behavioral deficits and infarct volumes relative to controls.Lastly, we demonstrated that the protective effect of 120 min of EA treatment prior to isehemic injury was abolished by pretreatment with the A1 receptor antagonist DPCPX (1 mg/kg, i.p.).Our results suggest that pretreatment with EA at the Baihui acupoint elicits protection against transient cerebral isehemia via adenosine A1 receptors.