Background: It is reported that ischemic penumbra is a dynamic process, in which irreversible necrosis in the center of ischemia propagates to the neighboring tissue over time. Recent research has indicated that mitochondrial adenosine triphosphate (ATP)-sensitive potassium channels (mitoK(ATP)) opener diazoxide plays an important role in cerebral protection; however, the role of mitochondrial calcium uniporter (MCU) in the effect of diazoxide on penumbra and infarct core remains unclear. Methods: Adult male Wistar rats were randomly divided into 5 groups: the Sham group, the ischemia-reperfusion (I/R) group, the diazoxide and ischemia-reperfusion (Dzx + I/R) group, the diazoxide and spermine and ischemia-reperfusion (Dzx + Sper + I/R) group, and the spermine and ischemia-reperfusion (Sper + I/R) group. The animals were exposed to 24-hour reperfusion after 2-hour ischemia. Diazoxide and spermine were administrated at 30 minutes or 10 minutes before the beginning of ischemia or reperfusion, respectively. After 24-hour reperfusion, animals were given neurologic performance tests and when overdosed with general anesthesia their brains were excised for infarct volume, apoptosis, and immunohistochemical. Results: Rats in the Dzx + I/R group displayed improved neurologic deficits, decreased infarct volume in cortex but not in subcortex, and apoptosis (evidenced by decreased terminal deoxynucleotidyl transferase-mediated dUTP nick end lebeling-positive percentage and the immunohistochemistry of cytochrome c) in cortex caused by ischemia/reperfusion. Rats in the Dzx + Sper + I/R group displayed worse neurologic deficits, larger infarct volume in cortex but not in subcortex, and more apoptosis both in penumbra and infarct core of cortex than those in the Dzx + I/R group. Conclusions: Results in our study suggested that diazoxide improved neurologic deficits, decreased infarct volume in cortex but not in subcortex, and apoptosis in cortex against ischemia/reperfusion injury is mediated by spermine.

Background: Recent research has indicated that mitochondrial adenosine triphosphate- sensitive potassium channels play an important role in cerebral protection, which involves in attenuating the calcium of mitochondria. However, the effect of diazoxide on cerebral ischemia-reperfusion and the role of spermine, the agonist of mitochondrial calcium uniporter (MCU), remain unknown. Objective: We investigated the effect of MCU opener spermine on diazoxide against focal cerebral ischemia-reperfusion injury in rats. Methods: Adult maleWistar rats were randomly divided into 5 groups: the Sham group, the I/R group, the Dzx + I/R group, the Dzx + Sper + I/R group, and the Sper + I/R group. Rats were exposed to 2-hour ischemia and 24-hour reperfusion. Diazoxide were administrated 30 minutes before ischemia, and spermine were given 10 minutes before reperfusion. Rats in the Sham group did not experience the process of ischemia-reperfusion. After 24-hour reperfusion, ratswere given neurological performance tests, overdosed with general anesthesia, and then their brains were excised for infarct volume, pathological changes, and biochemical evaluation and analysis. Results: Rats in the Dzx + I/R group displayed improved neurological deficits and decreased infarct volume and oxidative stress (evidenced by decreased nitric oxide and malondialdehyde but increased antioxidant enzymes [eg, glutathione peroxide and superoxide dismutase]) caused by ischemiareperfusion. The beneficial effects of diazoxide were significantly attenuated by spermine treatment. Rats in the Sper + I/R group displayed worse neurological deficits, larger infarct volume and more oxidative stress, and less antioxidant enzymes than those in the Dzx + I/R. Conclusions: Our results suggested that diazoxide, which improved neurological deficits and decreased infarct volume and oxidative stress against ischemia-reperfusion injury, is mediated by spermine.

It is known that mitochondrial ATP-sensitive potassium channels (mitoKATP) play a significant role in protecting cerebral function from ischemia-reperfusion injury, which is related with a decrease in the mitochondrial matrix calcium. However, the effect of mitochondrial calcium uniporter (MCU) on diazoxide-induced cerebral protection is still indistinct. The purpose of the present paper is to further observe the relationship between mitoKATP and MCU, and to probe the mechanism. Adult male Wistar rats were randomly divided into five groups: the Sham group, the I-R group, the Dzx+I-R group, the Dzx+Sper+I-R group, and the Sper+I-R group. Rats not in the Sham group were exposed to 2-hour ischemia followed by 24-hour reperfusion. Diazoxide and spermine were administrated 30 minutes before ischemia or 10 minutes before reperfusion, respectively. After 24-hour reperfusion, animals were given neurological performance tests, overdosed with general anesthesia, and then their brains were excised for infarct volume, pathological changes, and apoptosis analysis. The beneficial effects of diazoxide (improved neurological deficits, decreased infarct volume, and apoptosis, evidenced by the decreased expression of cytochrome c and Bax) were significantly neutralized by spermine. The results of the present work suggest that diazoxide-induced cerebral protection against ischemia-reperfusion injury is mediated by spermine through apoptotic pathway.

Objective To investigate whether diazoxide preconditioning protects cerebrum against i(s)chemia reperfusion injury via mitochondrial calcium uniporter(MCU)or not.Methods The ischemia reperfusion model was performed by thread occlusion of middle cerebral artery for 2 h,and then 24 h reperfusion.Fifty-two rats were randomly divided into four groups:group A (sham-operated group),group B(ischemia/reperfusion group),group C(diazoxide group),group D(diazozide-spermine group).After 24 h reperfusion,neuropsychological score,the mitochondrial calcium content([Ca2+]m),,the activity of superoxide dismutase (SOD)and glutathione peroxidase(GSH-Px),the content of malondialdehyde(MDA)and nitric oxide(NO)in ischemic hemisphere were observed in above groups respectively.Results Compared with group B,diazoxide preconditioning in group C improved neuropsychological score(13.1 ±0.8,P＜0.01),improved the activity of SOD(143 ±-18)U/mgprot and GSH-Px(84 ±8)U/mgprot(P＜0.05),and decreased the content of MDA(0.799 ±0.092)nmol/mgprot and NO(0.216±0.138)nmol/mgprot(P＜0.05)and[Ca2+]m (293±7)nmol/mgprot(P＜0.01).Spermine in group D attenuated the beneficial effects of diazoxide preconditioning in group C.Compared with group C,spermine attenuated neuropsychological score(8.0±0.7,P＜0.01)and the activity of SOD(128±7)U/mgprot and GSH-Px(73 ±6)U/mgprot(P＜0.05),and improved[Ca2+]m(322±10)nmol/mgprot(P＜0.01)and the content of MDA (0.955±0.141)nmol/mgprot and NO(0.575±0.292)nmol/mgprot(P＜0.05).Conclusions The effects of diazoxide preconditioning against cerebral ischemia reperfusion injury by attenuating[Ca2+]m and peroxidation injury in rats may involve in the suppression of MCU during reperfusion.