Induction of p38α and p38β MAPK in microglia and astrocytes of gerbil hippocampus following global ischemia

초록

The p38 kinase, a member of the mitogen activated protein kinase (MAPK), is abundantly expressed in adult brain. Several lines of evidences indicate that p38 MAPK activation is associated with pathological changes in the course of inflammatory and apoptotic processes in various cell types including neurons. Here we report that the differential activation of p38αand p38β occurs in adult mouse brain following transient global ischemia. Immunoreactivity of p38α which began to be induced as early as 4 hrs after ischemic insult continued to increase and reached maximum induction around 4 days after ischemic insult. Immunoreactivity was enriched in the microglia of the hippocampus as well as in frontal and parietal cortex of the brain, where the significant neuronal damage was concentrated. In contrast, immunoreactivity for p38β was markedly induced in astrocytes in hippocampus 4 days after ischemic insult and it remained for next several days. Marked induction of p38 MAPKs in glia cells following transient global ischemia raised the possibility that they play important roles associated with delayed neuronal death in post-ischemic brain. The differential induction of p38α and p38β MAPKs in microglia or in astrocytes in different time point after ischemic insult lmplies that the two p38 MAPK isoforms have distinct functions in the process.