脑室内注射脂多糖大鼠海马部位星形胶质细胞的变化

摘要

目的 研究侧脑室注射脂多糖(lipopolysaccharide,LPS)引发大鼠脑内炎性反应时,海马部位星形胶质细胞的变化.方法 健康雄性SD大鼠64只,采用数字表法随机分为0.9%氯化钠注射液(normal saline,NS)对照组和LPS实验组.LPS实验组大鼠右侧脑室一次性注射LPS 20 μL(1.25 g/L),NS对照组大鼠脑室内注射同等体积的NS.于注射后2、4、12及24周应用免疫组织化学染色方法观察大鼠海马部位星形胶质细胞特异性标志物-胶质原纤维酸性蛋白(glial fibrillary acidic protein,GFAP)阳性细胞的变化,并应用Western blotting方法检测大鼠海马部位GFAP蛋白表达的变化.结果 GFAP免疫组织化学染色结果显示,NS对照组大鼠不同时间点海马部位星形胶质细胞均未见明显激活.LPS实验组大鼠海马部位星形胶质细胞在LPS注射后2周明显激活,而LPS注射后4周和12周时海马部位星形胶质细胞激活不明显.LPS注射后24周时,LPS实验组大鼠海马部位星形胶质细胞又出现轻度激活.Western blotting结果显示,NS对照组大鼠不同时间点海马部位GFAP蛋白表达量无明显变化.LPS实验组大鼠海马部位GFAP蛋白表达量在LPS注射后2周时明显高于相应NS对照组,为相应NS对照组的2.39倍,差异有统计学意义(P<0.01).而注射后4周及12周时,LPS实验组大鼠海马部位GFAP蛋白表达量与相应NS对照组相比变化不明显.到注射后24周时,LPS实验组大鼠海马部位GFAP蛋白表达量为相应NS对照组的1.19倍,差异无统计学意义(P>0.05).结论 侧脑室注射LPS可在早期(注射后2周)显著引起大鼠海马部位星形胶质细胞的急性激活.%Objective To investigate the change; of astroeytes in the hippocampus in intraee;plialie intlanimation rat mode;l induced by intra-ventrieular injection ol lipopolysaeeharide ( LPS). Methods Altogether 64 hcuilthy male SD rats were assigned into normal saline (NS) -injected group or LPS-injeetcel group ranelomly. All injections were maele intra-ventriendarly on right siele of the rats with NS 20 μL or LPS 20 μL( 1.25 g/L). The changes of the the astroeytes in rat hippocampus were observed hy immunohistexhemieal staining using astroeyte-speeifie marker-glial fibrillary acidic protein(GFAP) at 2 weeks, 4 weeks, 12 weeks and 24 weeks after NS or LPS injection. Western blot was performed to deted GFAP expression in the hippocampus of the rats. Results Immunohistochemical staining with GFAP antibody showed that the astroeytes in the liippeK'ampus of rats were not activated at any time point after NS injection in NS-injected group. The astroeytes were activated obviously in the hippocampus of rats in LPS-injeeteel group at 2 weeks after LPS injection. The activation of astroeytes was not found in the hip peteam pus in LPS-injeeteel group at 4 and 12 weeks while the astroeytes were re-activated slightly in the liippeK'ampus of LPS-injee'teel group rats at 24 weeks after LPS injection. The result of Western blotting showed that the expression of GFAP in the hip peteam pus of NS-injeeted group rats did not change; significantly at any time point after NS injection. The GFAP protean level in the hippocampus of LPS-injeeteel group rats was 239% of that of NS-injected group rats at 2 weeks after injection (P<0. 01). At 4 and 12 weeks after injection, the GFAP protein level in LPS-injecteel group was similar to that of NS-injected group. The expression of GFAP protein in the hippocampus of LPS-injeeted group was 119% of that of NS-injeeted group at 24 weeks post injection with no significant difference (P>0. 05). Conclusion Intra-ventricular injection of LPS may result in acute and significant activation of astrocytes in the hippocampus of rats at early time(2 weeks post injection).