Immp2l Mutation Induces Mitochondrial Membrane Depolarization and Complex Ⅲ Activity Suppression after Middle Cerebral Artery Occlusion in Mice

Objective We previously reported that mutations in inner mitochondrial membrane peptidase 2-like(Immp2l)increase infarct volume,enhance superoxide production,and suppress mitochondrial respiration after transient cerebral focal ischemia and reperfusion injury.The present study investigated the impact of heterozygous Immp2l mutation on mitochondria function after ischemia and reperfusion injury in mice.Methods Mice were subjected to middle cerebral artery occlusion for 1 h followed by 0,1,5,and 24 h of reperfusion.The effects of Immp2l^(+/−)on mitochondrial membrane potential,mitochondrial respiratory complex III activity,caspase-3,and apoptosis-inducing factor(AIF)translocation were examined.Results Immp2l^(+/−)increased ischemic brain damage and the number of TUNEL-positive cells compared with wild-type mice.Immp2l^(+/−)led to mitochondrial damage,mitochondrial membrane potential depolarization,mitochondrial respiratory complex III activity suppression,caspase-3 activation,and AIF nuclear translocation.Conclusion The adverse impact of Immp2l^(+/−)on the brain after ischemia and reperfusion might be related to mitochondrial damage that involves depolarization of the mitochondrial membrane potential,inhibition of the mitochondrial respiratory complex III,and activation of mitochondria-mediated cell death pathways.These results suggest that patients with stroke carrying Immp2l^(+/−)might have worse and more severe infarcts,followed by a worse prognosis than those without Immp2l mutations.

Rethinking the necessity of low glucose intervention for cerebral ischemia/reperfusion injury

Glucose is the essential and almost exclusive metabolic fuel for the brain.Ischemic stroke caused by a blockage in one or more cerebral arteries quickly leads to a lack of regional cerebral blood supply resulting in severe glucose deprivation with subsequent induction of cellular homeostasis disturbance and eventual neuronal death.To make up ischemiamediated adenosine 5′-triphosphate depletion,glucose in the ischemic penumbra area rapidly enters anaerobic metabolism to produce glycolytic adenosine 5′-triphosphate for cell survival.It appears that an increase in glucose in the ischemic brain would exert favorable effects.This notion is supported by in vitro studies,but generally denied by most in vivo studies.Clinical studies to manage increased blood glucose levels after stroke also failed to show any benefits or even brought out harmful effects while elevated admission blood glucose concentrations frequently correlated with poor outcomes.Surprisingly,strict glycaemic control in clinical practice also failed to yield any beneficial outcome.These controversial results from glucose management studies during the past three decades remain a challenging question of whether glucose intervention is needed for ischemic stroke care.This review provides a brief overview of the roles of cerebral glucose under normal and ischemic conditions and the results of managing glucose levels in non-diabetic patients.Moreover,the relationship between blood glucose and cerebral glucose during the ischemia/reperfusion processes and the potential benefits of low glucose supplements for non-diabetic patients are discussed.