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Objective To evaluate the effects of ischemic postconditioning on brain injury induced by myocardial ischemia-reperfusion (I/R) in diabetic rats.Methods Diabetes mellitus was induced by intraperitoneal streptozotocin 60 mg/kg and confirmed by blood glucose level ＞ 16.7 mmol/L.Thirty male Sprague-Dawley rats,weighing 220-280 g,in which diabetes mellitus was successfully induced,were randomly allocated into 3 groups (n =10 each) using a random number tablegroup sham operation (group S),group I/R and group ischemic postconditioning (group P).Myocardial I/R was induced by occlusion of the anterior descending branch of the left coronary artery in I/R and P groups.Group P received 3 cycles of 10 s reperfusion followed by 10 s ischemia at the end of myocardial ischemia.The rats were sacrificed at 120 min of reperfusion and the brains were removed for microscopic examination and for determination of cell apoptosis (by TUNEL) and expression of interleukin-6 (IL-6),IL-8,IL-10,glycogen synthase kinase-3 beta (GSK-3β) and phosphorylated GSK-3β (pGSK-3β) (by immuno-histochemistry).Apoptotic index was calculated.Results Compared with group S,apoptotic index was significantly increased,IL-6 and IL-8 expression was up-regulated,and IL-10 and pGSK-3β expression was downregulated in I/R and P groups (P ＜ 0.01).Compared with group I/R,apoptotic index was significantly decreased,IL-6 and IL-8 expression was down-regulated,and IL-10 and pGSK-3β expression was up-regulated in group P (P＜0.01).There was no significant difference in GSK-3β expression among the 3 groups (P ＞ 0.05).The pathologic changes were significantly attenuated in group P as compared with group I/R.Conclusion Ischemic postconditioning can attenuate brain injury induced by myocardial I/R in diabetic rats,and inhition of activity of GSK-3β may be involved in the mechanism.