Identification of protein kinase C isoforms involved in cerebral hypoxic preconditioning of mice

Recently, accumulated studies have suggested that protein kinases C (PKC) play a central role in the development of ischemic-hypoxic preconditioning (I/HPC) in the brain. However, which types of PKC isoforms might be responsible for neuroprotection is still not clear, especially when the systematic investigation of PKC isoform-specific changes in brain regions was rare in animals with ischemic-hypoxic preconditioning. By using Western blot, we have demonstrated that the levels of cPKC βII and γ membrane translocation were increased in the early phase of cerebral hypoxic preconditioning. In this study, we combined the Western blot and immunostaining methods to investigate the effects of repetitive hypoxic exposure (H1-H4, n = 6 for each group) on membrane translocation and protein expression of several types of PKC isoforms, both in the cortex and hippocampus of mice. We found that the increased membrane translocation of nPKCε (P < 0.05, versus normoxic H0) but not its protein expression levels in both the cortex and hippocampus during development of cerebral HPC in mice. However, there were no significant changes in both membrane translocation and protein expression levels of nPKCδ, θ, η, μ, and aPKC ι/λ, ζ in these brain areas after hypoxic preconditioning. Similarly, an extensive subcellular redistribution of cPKCβII, γ, and nPKCε was observed by immunostaining in the cortex after three series of hypoxic exposures (H3). These results indicate that activation of cPKCβII, γ, and nPKCε might be involved in the development of cerebral hypoxic preconditioning of mice.