缺血性损伤对未成熟脑脑室下区神经新生的影响

Neurogenesis in the subventricular zone of neonatal rats after ischemic brain injury

摘要:

观察3日龄新生大鼠脑缺血后脑室下区（subventricular zone, SVZ）神经干细胞增殖及其向少突胶质细胞分化的变化，了解未成熟脑缺血性损伤后SVZ的自身修复作用。方法：3日龄新生Sparuge-Dawley大鼠96只随机分为实验组和对照组，实验组结扎双侧颈总动脉，造成脑缺血模型。采用5-溴脱氧尿嘧啶（BrdU）腹腔注射标记新生细胞，免疫荧光双标记方法观察脑损伤后不同时间点SVZ新生细胞（BrdU+）、新生神经干细胞（BrdU+/Nestin+）及新生少突胶质细胞（BrdU+/O4+）的变化。结果：①神经干细胞增殖变化：实验组缺血后SVZ BrdU+细胞增多，术后4 d达高峰（253.1±49.3），与同时间点对照组（133.5±17.7）相比差异有非常显著性（P<0.01）；双标结果显示SVZ BrdU+细胞大多为神经干细胞（Nestin+细胞）。②神经干细胞分化变化：实验组缺血后35 d新生少突胶质细胞（BrdU+/O4+阳性细胞）数目增加，主要分布在胼胝体（56.0±7.2）、隔核（45.0±11.9）、纹状体（34.5±4.2）、嗅球（46.5±6.6），与对照组（17.0±6.4，20.5±5.0，14.5±5.8，23.5±8.4）相比差异有非常显著性意义（P<0.01）。结论：①缺血性损伤可激活SVZ神经干细胞增殖，并促进其向少突胶质细胞分化；②未成熟脑SVZ具有损伤后自身修复作用。［中国当代儿科杂志，2009，11（5）：397-400］

Abstract:

OBJECTIVE: To study the proliferation and differentiation of neural stem cells in the subventricular zone (SVZ) in neonatal rats after bilateral common arteries occlusion. METHODS: Ninety-six 3-day-old Sparuge-Dawley rats were randomly divided into two groups: ischemia and control. Rats in the ischemia group were subjected to bilateral common arteries occlusion and the rats in the control group were sham-operated. All rats were administrated with 5-bromodeoxyuridine (BrdU) (50 mg/kg) via intraperitoneal injection. Rats were sacrificed and their brains were removed 1, 4, 7, 10, 14 and 35 days after ischemia. Using brain paraffin sections and immunofluorescence assays, the number of newborn cells in the SVZ was counted. Newborn neural stem cells and oligodendrocytes in the SVZ were observed, and then double marked with BrdU and nestin or osmium tetroxide (O4). RESULTS: The number of BrdU+ cells (neural stem cells) in the SVZ in the ischemia group was greater than in the control group 4, 7, 10 and 14 days after ischemia, and reached a peak at 4 days after ischemia (253.1±49.3 vs 133.5±17.7; P<0.01). By 35 days after ischemia, the number of BrdU+/O4+ cells (oligodendrocytes) in the corpus callosum (56.0±7.2 vs 17.0±6.4; P<0.01), the septal nuclei (45.0±11.9 vs 20.5±5.0; P<0.01), the striatum (34.5±4.2 vs 14.5±5.8; P<0.01) and the olfactory bulb (46.5±6.6 vs 23.5±8.4; P<0.01) in the ischemia group increased significantly as compared to the control group (P<0.01). CONCLUSIONS: Brain ischemia can activate the proliferation of neural stem cells in the SVZ and promote neural stem cells differentiation into oligodendrocytes. The immature brain may have the capacity for self-repair after ischemic brain injury.［Chin J Contemp Pediatr, 2009, 11 (5):397-400］