大鼠脑缺血再灌流时即早基因c-fos在脑组织表达的免疫组织化学研究

IMMUNOHISTOCHEMICAL STUDY OF c-fos IN THE CEREBRAL TISSUE IN RATS SUBJECTED TO ISCHEMIA AND REPERFUSION

为了研究 c-fos在大鼠缺血性脑损伤中的作用 ,本研究利用阻塞大鼠大脑中动脉 2 h后再灌流 0 .5～ 48h制成的局灶性脑缺血模型 ,用免疫组织化学技术观察了 c-fos的表达特点。结果证明 ,正常组、假性手术组 c-fos在神经元的表达呈阴性或弱阳性 ;再灌流 0 .5～ 48h组 ,胞核呈强阳性 ( +++)的神经元主要位于非大脑中动脉供血区 ,而缺血中心区的皮质、纹状体和视前区呈阴性 ( -)。缺血周边区 ,神经元胞核呈弱阳性 ( +)。正常组未发现 c-fos阳性的胶质细胞 ,假性手术组脑实质内胶质细胞团和侧脑室壁的胶质细胞 c-fos呈强阳性 ,再灌流 3h组脑室壁及深层的室管膜下区和皮质浅层、髓质等处胶质细胞为阳性 ,再灌流2 4～ 48h组缺血周边区和脑实质内的巨噬细胞、活化小胶质细胞呈强阳性 ;再灌流 48h组 ,白质如胼胝体内大量的反应性星形胶质细胞呈强阳性。本文结果提示 ,脑缺血时 c-fos对神经元具有神经保护作用 。

To study the involvement of c fos in ischemic cerebral injury in rats subjected to ischemia reperfusion, the focal cerebral ischemia was established by occluding middle cerebral artery for 2 hours and reperfusing for 0.5～48 h. The immunohistochemical method was used to examine c fos expression in the glia and neuron. In normal group and sham operated group, neuron showed c fos negative or weakly positive. At 0.5～48 h of reperfusion, neurons with nucleus strongly positive were mainly situated in areas not provided by MCA. On the contrary, neurons in the center of ischemia, such as cortex, striatum and preoptic area, were negative; neurons adjacent to ischemic center showed weakly positive. In normal group, glia showed c fos negative. In sham operated group, glial cells in cluster of glia of parenchyma and mural of lateral ventricle appeared strongly positive. At 3 h of reperfusion, a few of glial cells in mural of ventricle, SVZ, superficial layer and medulla showed positive. At 24～48 h of reperfusion, macroglia and active microglia in border areas of ischemia and parenchyma appeared c fos strongly positive; at 48 hours of reperfusion, many reactive astroglias of medulla, such as corpus callosum, showed c fos strongly positive. These data indicate that c fos plays a significant role in protecting neurons against ischemic injury, and that c fos is possibly connected with activation of microglias and astrocytes.