Previous studies have indicated that estrogen protects the brain from ischemic damage and regulates K-ATP channel activity; the present study was designed to address the involvement of K-ATP channels in the neuroprotective effects of estrogen in focal cerebral ischemia: in experiment 1, K-ATP mRNA and protein in the cortices of rats were compared among groups of ovariectomized rats (Ovx-1), Sham-operated rats (Sham-1), and ovariectomized rats administered 17 beta-estradiol (Estr-1). In experiment 2, neurobehavioral scores and infarct volume of rats were evaluated after middle cerebral artery occlusion in ovariectomized rats (Ovx-2), Sham-operated rats (Sham-2), ovariectomized female rats administered 17 beta-estradiol (Estr-2), and ovariectomized rats administered both 17 beta-estradiol and stereotactic injections of glibenclamide (Estr+G). Our results showed that the Kir6.2 and SUR1 mRNA and protein levels in the brain cortices of female ovariectomized rats were lower than those in Sham rats. However, the expression levels of Kir6.2 and SUR1 in brain cortices of ovariectomized rats recovered after supplementation with 17 beta-estradiol. The protective effects of 17 beta-estradiol were abolished by glibenclamide, a K-ATP channel blocker. This indicates that estradiol significantly upregulates the expression of K-ATP channel subunits and channel activity in the brain cortices of ovariectomized rats. This regulation is associated with the neuroprotective effects of estradiol. NeuroReport 23:952-957 (C) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.