Activations of nPKCF epsilon and ERK1/2 were involved in oxygen-glucose deprivation-induced neuroprotection via NMDA receptors in hippocampal slices of mice

Accumulated reports have suggested that activation of protein kinase C (PKC) isoforms may involve the activation of extracellular signal-regulated kinases (ERKs) in the neuronal response to ischemic/hypoxic stimuli. We have previously demonstrated that the membrane translocation of novel PKC (nPKC) epsilon increased in the early phase of cerebral ischemic/hypoxic preconditioning of mice. In this study, we used Western blot analysis and propidium iodide stain to determine whether the activations of nPKC epsilon; and ERKs were involved in oxygen-glucose deprivation (OGD)-induced neuroprotection via N-methyl-D-aspartate (NMDA) receptors. The hippocampal slices of mice were exposed to OGD for 10 (OGD 10) or 45 minutes (OGD45) to mimic mild (causing ischemic/hypoxic preconditioning) and severe (causing severe OGD) ischemia/hypoxia, respectively. We found that OGD10-induced nPKC epsilon membrane translocation was mediated by NMDA receptors, and both OGD10 and NMDA (I mu M, 30min) pretreatment could protect Cornu Ammonis region I neurons against the subsequent severe OGD45. In addition, nPKC epsilon translocation inhibitor, epsilon V1-2 (1 mu M, 30 min), and ERKs upstream mitogen-activated protein/extracellular signal regulated kinase kinase inhibitor, PD-98059 (20 mu M, 30min), could significantly inhibit OGD10 and NMDA-induced neuroprotection. These results suggest that OGD10-induced neuroprotection against severe OGD45 in the Cornu Ammonis region I region of the hippocampal slices was mediated by the activations of NMDA receptors, nPKC epsilon, and the downstream ERKs.