未成熟大鼠缺氧缺血性脑白质损伤中F-actin及RhoA变化  

Expression of F-actin and RhoA in experimental hypoxic-ischemic white matter damage in premature SD rats

作　　者：李晋辉[1] 姚裕家[1] 石晶[1] 李德渊[1] 

机构地区：[1]四川大学华西第二医院新生儿科,成都610041

出　　处：《中华儿科杂志》2007年第10期769-772,共4页Chinese Journal of Pediatrics

基　　金：教育部高等学校博士学科点专项科研基金项目资助(20050610071)

摘　　要：目的研究丝状肌动蛋白(filament actin,F-actin)和 RhoA 在未成熟大鼠缺氧缺血(hypoxic-ischemia,HI)性脑白质损伤(white matter damage,WMD)中的变化,探讨两者作用及可能存在的关系。方法 2日龄 SD 大鼠(n=184只)随机分为14组:7个时段 WMD 组(HI 后12、24、48、72 h,7、14、28 d)和7个相应时段对照组。采用 Back 方法制作 WMD 动物模型。HE 染色观察脑组织病理学变化,电镜观察超微结构改变。采用荧光免疫组织化学方法(n=80只)和实时荧光定量 PCR(n=80只)分别观察 HI 后12、24、48、72 h,7 d 脑组织中 F-actin 和 RhoA 的变化。结果 (1)光镜和透射电镜检查脑组织,符合 WMD 的病理及超微结构也改变。(2)WMD 组胞膜荧光染色不连续细胞百分比与对照组相比明显增高(P<0.05),WMD 组分别为0.32±0.04,0.43±0.04,0.56±0.03,0.65±0.04,0.87±0.03;对照组为0.02±0.01,0.02±0.01,0.01±0.01,0.02±0.01,0.02±0.01。(3)WMD 组 RhoAmRNA 表达在 HI 后12、24、48、72 h 均明显高于对照组(P<0.05),WMD 组分别为1.205,2.415,4.830,1.500;对照组为0.300,0.375,0.375,0.530。HI 后7 d WMD 组 RhoAmRNA表达接近对照组(P>0.05)。结论 (1)2日龄未成熟大鼠 WMD 模型建立成功。(2)HI 后,F-actin在细胞内分布发生变化:细胞膜上分布减少,胞浆中分布增高,该变化可能与神经细胞生长锥的塌陷和回缩有关。(3)WMD 中 RhoA 可能在一定程度上参与了 F-actin 分布表达的变化,但并不是影响F-actin 的惟一因素。Objective White matter damage （WMD） in preterm infants is a well-recognized serious complication of prematurity. The collapse of cell skeleton of growth cone after hypoxia-ischemia （HI） is considered as the basic neuropathologic change of the long-term residuals of premature white matter damage. F-actin is the major component of cell skeleton and maintains the normal form of cells, its function and potential mechanism of WMD have not been reported. In this study, changes of F-actin and its influencing factor RhoA were investigated. Methods Totally 184 Sprague-Dawley （SD） rats （ age 2 days, body weight 6 to 8 grams）were randomly divided into 14 groups： 7 different time WMD groups （HI 12 h, 24 h, 48 h, 72 h,7 d, 14 d, 28 d） and 7 corresponding control groups. The 2 day-old SD rats were subjected to ligation of right carotid artery （ ischemia）, and then they were put into a box full with 6% oxygen and 94% nitrogen for 4 hours （ hypoxia）. The light microscopy was used to observe the brain pathological changes and the electron microscopy was used to detect the brain ultrastructural changes after hypoxia and ischemia. Eighty SD rats were used for flurescent-immunohistochemical method to detect the distribution of F-actin in cell membrane and cytoplasm of beth WMD groups and the control groups at 12 h, 24 h, 48 h, 72 h, 7d after HI respectively. The distribution of F-actin was reflected by the percentage of non-integrity cells. Another 80 SD rats were used for real time RT-PCR to detect the expression of RhoAmRNA in the white matter tissue of beth WMD groups （HI 12 h, 24 h, 48 h, 72 h, 7 d） and the control groups. Results （ 1 ） Necrosis of lateral ventricle tissue was observed by 72 h after HI. Dilatation of ventricle and formation of capsular space beneath white matter had been observed by 14 d after HI. （2） Disregulation, pyknosis, mitochondrion swelling and chromatin agglutination were observed in WMD groups. The maldevelopment of myelins in WMD groups was detected at 1 h aft

关 键 词：大鼠 缺氧缺血 脑 肌动蛋白类 γhoA GTP结合蛋白类 

分 类 号：R722.6[医药卫生—儿科]