ABSTRACT
This study was aimed to explore the function of c-Jun N-terminal kinase (JNK) signaling pathway in the induction of brain ischemic tolerance, and observe the function of Shu-Xue Tong-Mai (SXTM) capsule pretreatment. Ischemic preconditioning was performed for 3 min on rats to induce cerebral ischemic tolerance. Rat model of cere-bral ischemia reperfusion (the ischemia pretreatment group, I/R group) was established 24 h later. Western blot was used to detect the protein expression of JNK and phosphorylation of c-Jun N-terminal kinase (P-JNK), comparing to the expression with the sham operation group, I/R group and SXTM capsule group. Tunel method was applied to de-tect the apoptosis of neurons. Relationship between expression of JNK, P-JNK and apoptosis of neurons was also studied. The results showed that compared with the model group, expressions of P-JNK in ischemia preconditioning group and SXTM group were declined significantly (P < 0.05); and the apoptosis of neurons quantity was also de-clined (P< 0.05). It was concluded that ischemia preconditioning can decrease the apoptosis of neurons in cerebral ischemia reperfusion, and improve neurologic function. Its mechanism related to the inhibition of JNK signaling path-way. SXTM capsule pretreatment can protect the cerebral by inhibiting the JNK signaling pathway.
ABSTRACT
ObjectiveTo investigate the effect of focal ischemic preconditioning (IPC) on the expression of protein kinase-like endoplasmic reticulum kinase ( PERK ) and glucose-regulated protein 78 (GRP78) mRNA and protein after focal cerebral ischemia/reperfusion (I/R) in rats.MethodsAll 120 male SD rats were randomly divided into three groups: sham-operation group,middle cerebral artery occlusion (MCAO) group and brain ischemia preconditioning (BIP) group.Each group was further divided into 4 subgroups according to 12 h,1,2 and 3 d after I/R.The IPC models were made in order to measure the expression of PERK,GRP78 mRNA and protein by in situ hybridization and Western blot,and the apoptosis rate of neuron by flow cytometry. Results ①The expression of PERK mRNA increased and reached the peak at 12 h,then decreased continuously after 1 d.BIP could decrease its expression.The expression of PERK protein increased at 12 h and reached the peak at 24 h,then decreased continuously after 2 d.BIP could decrease its expression.②The expression both of GRP78 mRNA and its protein all increased and reached the peak at 12 h,then decreased continuously.BIP could increase their expression (mRNA:12 h: 136.70±9.53,F=32.265; 24 h:147.54 ±9.97,F=54.920; 2 d:158.16 ±9.44,F=45.374; 3d: 165.85±10.26,F=16.493,P＜0.05; protein:12 h: 1.319±0.116,F=5.619,P＜0.05; 24 h: 1.226±0.108,F=33.742,P＜0.01; 2 d:1.183 ±0.112,F =46.556,P ＜0.01; 3 d:1.115± 0.098,F =11.730,P＜0.05).③The rate of apoptosis neuron of rats in MCAO increased markedly at 12 h after reperfusion,and reached the peak at 1 d,then decreased continuously.BIP could decrease the rate of apoptosis neuron. Conclusion BIP can protect neurons through inhibiting the expression of PERK and inducing the expression of GRP78 after endoplasmic reticulum stress in rats.