没食子酸丙酯对脑缺血大鼠神经元SAPK/JNK及p38MAPK激活的抑制作用

目的探讨没食子酸丙酯对大鼠脑缺血再灌注模型缺血区周边组织神经元损伤的保护作用及其可能机制。方法通过Nissl和TUNEL染色法检测阳性神经元数量，蛋白免疫印迹、免疫组化法观察活化型Caspase-3，SAPK/JNK，p38MAPK及其磷酸化组分的表达。结果没食子酸丙酯干预后，SAPK/JNK，p-SAPK/JNK(1 h)，p38MAPK，p-p38MAPK(6 h)及活化型Caspase-3(12 h)表达均减弱，TUNEL阳性神经元减少(24 h)，Nissl阳性神经元增多(24 h)，神经元凋亡率明显降低。结论没食子酸丙酯保护缺血再灌注后神经元损伤的机制可能与抑制SAPK/JNK及p38MAPK的激活有关。

Inhibitory action of propyl gallate on the activation of SAPK/JNK and p38MAPK induced by cerebral ischemia-reperfusion in rats

AIM: To explore the protective effect of propyl gallate against neuronal injury in the boundary zone of the infarction area in the rat cerebral ischemia-reperfusion model and its possible mechanism. METHODS: Transient focal ischemia induced by middle cerebral artery occlusion in the rats was established by ligation of the left internal carotid artery for 2 h. Rats were treated by propyl gallate with different doses (23.5, 47 and 94 micromol x kg(-1)) for three days before operation. Coronal brain sections were collected after 1 , 2, 4, 6, 12 and 24 h of reperfusion, neuronal injury in the boundary zone of the infarction area was evaluated by TUNEL and Nissl staining. The expression of activated Caspase-3, total SAPK/JNK, p38MAPK and their phosphorylation (Thr183/Tyr185, Thr180/Tyr182) was investigated by immunohistochemistry and Western blotting with corresponding antibodies. RESULTS: Although SAPK/JNK immunoreactivity did not increase at each time point in the boundary zone of the infarction area after reperfusion, p-SAPK/JNK immunoreactivity increased significantly at 1 h and then decreased gradually, and p38MAPK immunoreactivity was enhanced at each time point, peaked at 6 h. Expression of p-p38MAPK peaked at 6 h. Activated Caspase-3 immunoreactivity appeared at 6 h in the boundary zone of the infarction area and peaked at 12 h. TUNEL positive neurons were observed at 12 h and became more abundant at 24 h. The number of Nissl positive neurons decreased gradually and apoptosis ratio of neurons peaked at 24 h. Propyl gallate reduced the immunoreactivity of SAPK/JNK, p-SAPK/JNK, p38MAPK and p-p38MAPK markedly at 1 and 6 h. Propyl gallate with doses of 47 and 94 micromol x kg(-1) were more effective. CONCLUSION: Inhibition on the activation of SAPK/JNK and p38MAPK is the possible protective mechanism of propyl gallate against neuronal injury induced by cerebral ischemia-reperfusion.