Regeneration of injured axons with oligodendrocytic signal-processing systems as a marker

我们研究了脑缺血和脑损伤模型中中脑特异性蛋白酶（myelencephalon-specific protease，MSP）的mRNA和蛋白表达。MSP是少突胶质细胞特异性丝氨酸蛋白酶，其表达与轴突再生有关。结果：脑缺血后3 ~ 7天，在缺血区周围的少突胶质细胞中检测到MSP mRNA和蛋白的表达。问题是MSP的表达是由缺血周围少突胶质细胞的直接缺血损伤引起的，还是由水肿液形成对少突胶质细胞的间接影响引起的。为了回答这个问题，我们建立了冷损伤模型，在该模型中，病变周围出现水肿，但少突胶质细胞没有发生缺血性损伤。在冷损伤模型中检测到MSP在冷损伤后第5天开始表达<th>。由此我们得出结论，水肿液扩展到周围病变可能激活少突胶质细胞并表达MSP mRNA和蛋白表达。我们做了MSP和少突胶质细胞特异性标记物CNP 13的双重免疫染色，并确定这两个标记物共定位于同一少突胶质细胞。结果表明，水肿液激活少突胶质细胞和轴突再生的作用。我们还对MSP进行了Western印迹，并鉴定MSP蛋白在19 kDa（真实MSP蛋白）和37、40和50 kDa处具有条带。37 kDa条带在伤后6小时和5- 7天体积增大。这两个反应性产物峰提示了少突胶质细胞激活的两种机制，即通过神经网络的直接刺激和通过水肿液的延伸的间接刺激。在蛛网膜下腔出血模型和脑出血模型中也发现了类似的结果。

We have studied mRNA and protein expression of myelencephalon-specific protease (MSP) in the brain ischemia and brain injury model in rats, because MSP is oligodendrocyte-specific serine protease and MSP expression is relating to axonal regeneration. As a result, we have detected MSP mRNA and protein expression in the oligodendrocytes locating at peri-ischemic area 3 to 7 days after cerebral ischemia. Question then arises whether MSP expression is caused by direct ischemic injury to the peri-ischemic oligodendrocytes or indirect effect of edema fluid formation on oligodendrocytes. To answer this question, we developed cold injury model in which edema developed around lesion but ischemic injury to the oligodendrocyte was not occurring. We detected in the cold injury model that MSP expression occurred on the 5^<th> day after cold injury. With this result we concluded that edema fluid extending to the surrounding lesion might activate oligodendrocytes and express MSP mRNA and protein expression. We did double immunostaining of MSP and oligodendrocyte-specific marker CNPase, and identified that both markers were co-localizing in the same oligodendrocyte. The results suggest that edema fluid activates oligodendrocytes and act for regeneration of axons. We also did Western blotting of the MSP and identified that MSP proteins has bands at 19kDa (authentic MSP protein) and 37, 40 and 50kDa's. The 37kDa bands increased its volume at 6 hours and 5-7days after cold injury. Those two peaks of reactive production suggested two mechanism of oligodendrocytes activation, initial direct stimulation through neuronal network and secondary indirect stimulation through edema fluid extension. That similar result was also identified in the subarachnoid hemorrhage model and intracerebral hemorrhage model.