碱性成纤维生长因子对HIBD新生大鼠脑组织nestin表达的影响

Effect of basic fibral growth factor on nestin expression in neonatal rats following hypoxic-ischemic brain damage

摘要:

目的：碱性成纤维生长因子(bFGF)对缺氧缺血脑损伤(HIBD)的重要修复作用已引起国内外学者普遍关注,但bFGF对于增强脑损伤后神经再生和修复能力的机制尚不完全清楚。巢蛋白(nestin)是一种中间丝蛋白,是胚胎神经干细胞的特征性标记,神经系统发生病变或损伤引起再生时可诱导其再表达。该研究旨在探讨外源性bFGF对HIBD新生大鼠脑组织nestin表达的影响及bFGF对新生大鼠HIBD后的神经修复机制,为临床应用bFGF奠定理论基础。方法：84只新生7日龄SD大鼠,分为3组,每组28只①假手术组;②缺氧缺血组;③bFGF干预组。结扎大鼠左侧颈总动脉和行8%低氧暴露制备新生大鼠HIBD模型。假手术组仅游离左颈总动脉但不结扎和行缺氧处理。bFGF干预组大鼠缺氧缺血后立即给予bFGF腹腔注射,4000U/kg,每天1次。每组再随机分为缺氧缺血后3,12,24h,3,7,14d组处死,每组4只。采用SABC免疫组化方法检测nestin蛋白的表达。结果：假手术组nestin蛋白在海马、室管膜弱表达,在皮质不表达。nestin蛋白在大鼠缺氧缺血脑损伤后的表达增强,nestin蛋白7d达高峰。经bFGF干预后nestin蛋白表达较缺氧缺血组增高,缺氧缺血后1d时有统计学差异,持续至14d(P<0.05)。结论：外源性bFGF可以明显增加新生大鼠缺氧缺血脑损伤后nestin蛋白表达,在缺氧缺血脑损伤后的神经元再生与修复中发挥一定保护作用。

Abstract:

OBJECTIVE: Basic fibral growth factor (bFGF) might have a role in the restoration and regeneration of injured neurons following hypoxic-ischemic brain damage (HIBD), but its mechanism has not been fully elucidated. Nestin is an intermediate filament protein expressed in dividing cells during the early stages of CNS development, but it can be reinduced in adults during regeneration of injured neurons after CNS injury. This study investigated the effect of exogenous bFGF on nestin expression in neonatal rats following hypoxia-ischemia (HI) and to explore the possible mechanism. METHODS: Eighty-four 7-day-old SD rats were randomly assigned into a Sham-operation group, a HIBD group and a bFGF intervention group (n=28 each). HIBD was induced by ligation of the left carotid artery along with 8% oxygen exposure in neonatal rats from the latter two groups. The Sham-operation group was not subjected to HI. The bFGF intervention group received an intraperitoneal injection of bFGF daily (4 000 U/kg). Each group was randomly subdivided into groups sacrificed immediately, at 3, 12 and 24 hrs and 3, 7 and 14 days after HI (n=4). The expression of nestin in the cerebral cortex, hippocampus and extraventricular zone was examined with immunohistochemical staining and image quantitative analysis. RESULTS: Nestin was weakly expressed in the hippocampus and extraventricular zone and not expressed in the cortex in the Sham-operation group. The nestin in the cortex, hippocampus and extraventricular zone was significantly increased after HIBD, peaking at 7 days. bFGF treatment increased the nestin expression in the cortex, hippocampus and extraventricular zone and statistical differences were observed from 1 to 14 days after HI when compared with the untreated HIBD group. CONCLUSIONS: Exgeonous bFGF can up-regulate the nestin expression in neonatal rats following HIBD. The effects of restoration and regeneration of bFGF on injured neurons may be associated with increased nestin expression in neonatal rats.