Role of p38 MAPK on cerebral edema and AQP4 expression after cerebral ischemia reperfusion in rats

Objective To investigate the role of p38 MAPK on cerebral edema and Aquaporin-4(AQP4) expression after cerebral ischemia reperfusion in rats.Methods Fifty-four SPF male SD rats weighing 240 ～ 260g were randomly divided into 3 groups: sham operation group(sham group);ischemia reperfusion group(group I/R);p38 inhibitors group(group SB).The middle cerebral artery ischemia/reperfusion rats model was established by the suture method with some modification.The group I/R and group SB rats were exposed to 10% DMSO and SB203580 for 15min before suffered from cerebral ischemia.The neurologic exams were assessed at 24h after reperfusion,the rats were sacrificed after anesthetization.To estimate cerebral edema,the wet-dry ratio was measured.Western blot was used to detect the expression of p-p38 and AQP4 in the infarct region.Results(1) The neurologic function deficit was serious in group I/R and group SB compared to Sham group(P 0.05).(2) I/R caused enhanced expression of p-p38 protein and this effect was blocked by SB203580.AQP4 protein expression increased after I/R(P 0.05) and the ischemic hemisphere cerebral edema was increased compared with Sham group(P 0.05).Application of the SB203580 depressed AQP4 up-regulation(P 0.05) and cerebral edema of ischemic hemisphere was lower in the SB group(P 0.05).Conclusion p38MAPK signaling pathway participates in brain edema after cerebral ischemia-reperfusion in rat and blocking this pathway can attenuate AQP4 up-regulation and mitigate the cerebral edema.