ABSTRACT
Objective To investigate the neuroprotective effect and its mechanism of p38 mitogenactivated protein kinase inhibitor after subarachnoid hemorrhage (SAH).Methods Twenty-seven SPF-grade adult male SD rats were selected to induce a SAH model using the prechiasmal pool blood injection.Three dead rats were excluded.Twenty-four rats were randomly divided into four groups:sham operation group,SAH group,dimethyl sulfoxide (DMSO) group,and DMSO +p38 inhibitor group (n =6 in each group).Western blot was used to detect the expression levels of p38,phosphorylation p38,Parkinson's disease protein 7 (DJ-1),autophagy associated gene 5 (Atg5),autophagy adaptor protein p62,microtubule-associated protein Ⅰ Light Chain 3 (LC3-Ⅰ),microtubule-associated protein Ⅱ light chain 3 Ⅱ (LC3-Ⅱ),and the Garcia neurological function score was used to judge the nerve injury.PC12 cell oxygenated hemoglobin was used to induce an in vitro SAH model.They were completely randomly divided into four groups:sham operative group,SAH group,DMSO group,and DMSO + p38 inhibitor group.Fluorescent probe JC-1 was used to observe the changes of mitochondrial membrane potential.Results (1) There were significant differences in the expression of p38,phosphorylation-p38 and DJ-1 in rat brain tissue among the 4 groups (F values were 94.959,150.293 and 698.476,respectively,all P ＜ 0.01).There were significant differences in mitochondrial membrane potential in PC12 cells among the 4 groups (F value was 24.989,P ＜ 0.01).There were significant differences in the expression levels of autophagy related protein LC3-Ⅱ/LC3-Ⅰ ratio,Atg5 and p62 in rat brain tissue among the 4 groups (F values were 235.319,110.490 and 36.311,respectively,all P ＜ 0.01).There was significant difference in nerve function score among the 4 groups (F value was 25.550,P ＜ 0.01).(2) Compared with the sham operative group,the expression levels of p38,phosphorylation-p38 and DJ-1 were upregulated significantly after SAH (from 0.43 ±0.06,0.41 ±0.02 and 0.07 ±0.01 to 0.61 ± 0.08,0.79 ± 0.07 and 0.17 ± 0.03,respectively,all P ＜ 0.01),mitochondria membrane potential depolarization (from 8.29 ±0.28 to 9.23 ±0.42,P ＜0.01);upregulation of Atg5 expression and increase of LC3-Ⅱ/LC3-Ⅰratio (from 0.23 ± 0.04 and 0.25 ± 0.04 to 0.47 ± 0.04 and 0.46 ± 0.04,respectively,all P ＜ 0.01),down regulation of p62 expression (from 1.09 ± 0.14 to 0.54 ± 0.10,P ＜ 0.01);neurological score was decreased (from 17.5 ± 0.6 to 11.3 ± 2.7,P ＜ 0.01);p38 inhibitor was significantly down regulated the expression of phosphorylation-p38 after SAH (from 0.79 ± 0.07 to 0.47 ± 0.04,P ＜ 0.01),the expression of DJ-1 was up-regulated (from 0.17 ± 0.03 to 1.02 ± 0.06,P ＜ 0.01),mitochondrial membrane potential recovery (from 9.23 ±0.42 to 8.47 ±0.36,P ＜0.01),cell autophagy related protein LC3-Ⅱ/LC3-Ⅰ ratio and Atg5 were upregulated(from 0.46 ±0.04 and 0.47 ±0.04 to 0.77 ± 0.06 and 0.95 ± 0.12,all P ＜ 0.01),p62 expression returned to the levels of SAH group (from 0.57 ± 0.09,to 0.54 ± 0.10,P =0.650),and the neurological score was significantly improved (from 11.3 ± 2.7 to 15.5 ± 1.0,P ＜0.01).Conclusions After SAH,the p38 inhibitor downregulates the activity of2 phosphorylation p38.It may inhibit abnormal autophagy and maintain mitochondrial function by up-regulating the expression of DJ-1 protein,and then play a neuroprotective function.