ERK通路参与蛇毒型神经生长因子诱导的中枢神经保护作用

Erk pathway involved in NGF-- induced pprotective effect of the central nervous system

目的观察经侧脑室给予蛇毒型神经生长因子（vNGF）对脑缺血再灌注损伤后细胞外信号调节激酶（extracellular signal—regulated kinase，ERK）表达的影响，探讨外源性vNGF通过影响ERK的表达减轻神经元损伤的可能机理。方法取健康清洁级雄性Wistar大鼠，按随机分组原则分为2d组（n=30）、7d组（n=30）、14d组（n=30）。每个时间点再分为五个亚组vNGF25U、vNGF50U、vNGF100U、生理盐水对照组、以及假手术组，每个亚组6只大鼠。生理盐水对照组和vNGF各亚组大鼠采用大脑中动脉线栓法建立局灶性脑缺血-再灌注损伤模型，术后各时间点vNGF亚组采用改良的侧脑室置管术法给予相应剂量蛇毒型神经生长因子，生理盐水对照组给予等渗盐水。采用免疫组织化学法测定术后第2d、第7d以及第14d缺血皮质周围和海马CA3／DG区ERK阳性细胞数。结果（1）与对照组相比，经侧脑室给予蛇毒型神经生长因子各组大鼠神经功能明显改善，显示了外源性补充蛇毒型神经生长因子的明显正性干预作用。（2）ERK免疫组织化学结果显示：经侧脑室给予vNGF各亚组ERK阳性细胞在缺血皮质周围和海马CA3／DG区第2d表达为高峰，第7d明显下降，第14d恢复基线水平。与相应时间点对照组相比，呈明显下降趋势。结论局灶性脑缺血再灌注后磷酸化ERK表达增加，NGF可能通过抑制ERK途径而发挥神经保护作用。

Objective To investigate the effect of intracereb --roventricular administration of vevom nerve growth factor on the effect s of phosphorylated extraeellular signal--regulated kinase in rats with cerebral ischemical reperfusion injury. Methods Wistar rats were randomly divided into three groups： 2 days group, 7 days group and 14 days group （ n =30 in each group） ,then each group randomly assigned to vNGF 25U , vNGF 50U , vNGF 100U , sham--operation, and ischemia/reperfusion control subgroups （ n = 6 in each subgroup） . Then , a focal cerebral ischemia / reperfusion model was induced by middle cerebral artery intraluminal suture occlusion （MCAO） method in the I/R control and vNGF subgroups. Normal saline or Different concentrations vNGF was administered via intracerebroven- tricular to the I/R control or vNGF subgroups rats per day according to the corresponding time points. The numbers of positive cells of ERK＋ cells in the Peri--ischemic cortex and Hippoeampus CA3/DG were assessed by immunohistochemical method in the corresponding time points. Results As compared with control subgroups, snake venom nerve growth factor subgroups which was administered via intrace- rebroventricular, the neurological function began to recover in the first two days. which showed its positive intervention effects markedly. The results of ERK immuno-- histochemistry showed that., the num- bers of ERK positive cells in Peri-ischemic cortex and Hippocampus CA3/DG of snake venom nerve growth factor subgroups reach the peak at 2 days after the procedures, began to decline at 7 days, then restored baseline levels at 14 days. As compared with the I/R control subgroups, snake venom nerve growth factor subgroups showed a clear downward trend. Conclusions Focal cerebral ischemia-- reperfusion injury can induces the expression of phosphorylated ERK, NGF may play a neuroprotective effect via inhibit ERK signal transduction pathways.