Hypoxic/ischemic preconditioning attenuate PKCδ-medi-ated injury in patients and mice with cerebral infarction

Objective:cerebral ischemic/hypox-ic preconditioning(I/HPC)is an endogenous strategy in which brief periods of sublethal ischemia/hypoxia render neural tissues resistant to subsequent ischemic/hypoxic damage.This phenomenon has been found in the brain,heart,liver,intestine,muscle,kidneys,and lung.How-ever,whether HPC has a protective effect on secondary cerebral ischemic injury or protein kinase Cδ(PKCδ)within ischemic patients and animal models is still un-clear.Methods:using a hypoxic preconditioned mouse model and a middle cerebral artery occlusion mouse mod-el,combined with 2,3,5-triphenyl tetrazolium chloride(TTC)staining,SDS-polyacrylamide gel electrophoresis(SDS-PAGE),and Western blot,we observed changes in infarction size,density,edema ratio,and changes in PKCδand membrane translocation within the ischemic cortex of the middle cerebral artery occlusion(MCAO)mice.Results:HPC can attenuate neurological deficits and cerebral ischemic injuries of mice following MCAO,including decreases in infarct size,edema ratio,densities of infarct area,and neuron loss.In addition,HPC inhib-its PKCδmembrane translocation in the penumbra of the MCAO-induced ischemic cortex.We found that admin-istration of PKCδ-specific inhibitor dV1-1 mimics the neuroprotective effects of HPC,and nonisoform-specif-ic activation of PKC can partially abolish HPC-induced neuroprotection.Ischemic preconditioning decreased the levels of PKCδin the serum of patients with cerebral in-farction and reduced the cerebral nerve damage caused by ischemia.Conclusion:hypoxic/ischemic precondi-tioning attenuates PKCδ-mediated injury in patients and mice.These findings enrich our understanding of the sig-nal transduction mechanism underlying cerebral HPC and provide clues to developing medicine against ischemia/hypoxia-induced cerebral injuries.