p38 MAPK Participates in the Mediation of GLT-1 Up-regulation During the Induction of Brain Ischemic Tolerance by Cerebral Ischemic Preconditioning.

Our previous study has proved that the up-regulation of glial glutamate transporter 1 (GLT-1) played an important role in the acquisition of brain ischemic tolerance after cerebral ischemic preconditioning (CIP) in rats. However, little is known about the mechanism involved in the up-regulation of GLT-1 in the process. The present study investigates whether p38 MAPK, ERK1/2, and/or JNK participates in the up-regulation of GLT-1 during the induction of brain ischemic tolerance by CIP. It was found that CIP significantly enhanced the expression of p-p38 MAPK without altering p-ERK1/2 and p-JNK expression in the CA1 hippocampus. Inhibition of p38 MAPK function by its selective inhibitor SB203580 or knockdown p38 MAPK expression by its antisense oligodeoxynucleotides (AS-ODNs) suppressed the induction of brain ischemic tolerance. Furthermore, p38 MAPK was activated earlier than the up-regulation of GLT-1 in the CA1 hippocampus after CIP. Meanwhile, the expression of p-p38 MAPK by astrocytes was increased, and p38 MAPK AS-ODNs dose-dependently inhibited the up-regulation of GLT-1 after CIP. Taken together, it could be concluded that p38 MAPK participates in the mediation of GLT-1 up-regulation during the induction of brain ischemic tolerance after CIP.