BACKGROUND: Schwann cell-derived neurotrophic factor is a bioactive protein isolated and purified from the kytoplasm of Schwann cell. It can obviously maintain the survival of spinal cord anterior horn motor neuron and promote the regeneration of peripheral nerve.OBJECTIVE: To observe the protective effect of Schwann cell-derived neurotrophic factor on the high injury of peripheral nerve-induced apoptosis of sensory neurons in spinal dorsal root ganglia.DESIGN: Randomized and controlled animal experiment.SETTING: Shenzhen Second People's Hospital.MATERIALS: Totally 30 3-week-old SD infant rats, of clean grade and either gender, were used in this experiment. They were randomly divided into neurotrophic factor group and control group with 15 rats in each one.Left sides of the animals in both two groups were set as normal sides and right sides as injured sides.METHODS: This experiment was carried out at the Experimental Animal Center, Medical College of Sun Yat-sen University from May 2003 to July 2003. ① L4.5 nerve root high-mutilation animal models were developed on the rats in two groups. Proximal nerve stump was connected with silicone tube. According to grouping, 60 mg/L Schwann cell-derived neurotrophic factors and 20 μL normal saline were injected into the silicone tubes respectively. Two ends of silicone tube were enveloped with vaseline.② Sample collecting was conducted at postoperative 4 weeks, survival rate and morphological change of sensory neurons in dorsal root ganglia of injured nerve was observed.MAIN OUTCOME MEASURES: ① Gross observation of sciatic nerve regeneration at injured side of the rats in two groups ② Survival of sensory neurons in dorsal root ganglia ③ Morphological change of sensory neurons in dorsal root ganglia.RESULTS: All the 30 rats entered the stage of result analysis. ① Gross observation of sciatic nerve regeneration: In the neurotrophic factor group,nerve new born axon grew along silicone tube, with 1cm in length; there were few and thin newborn axons in control group with 0.8 cm in length.② Survival of neuron in dorsal root ganglia of the rats in two groups: There was little fibrous tissue proliferation in the dorsal root ganglion in neurotrophic factor group. The loss of neurons was not obvious and the survival rate was 91.8%. Obvious fibrous tissue proliferation appeared in the dorsal root ganglia in control group, and a great many neurons were lost with the survival rate of 58.6%. Survival rate of neurons was 33.2% higher in neurotrophic factor group than in control group (P ＜ 0.01 ). ③ Morphological change of neurons in dorsal root ganglia: The diameter and area of neurons in dorsal root ganglia were significantly lower in control group than in neu rotrophic factor group and normal side [(21.8±1.4) μm,(373.1±50.9) μm2 vs (24.8±1.1) μm, (482.8±42.2) μm2 and (24.5±1.3) μm, (471.5±51.4) μm2,P ＜ 0.01], while there were no significant difference in diameter and area of neurons between neurotrophic factor group and normal side(P ＞ 0.05).CONCLUSION: Schwann cell-derived neurotrophic factors have obvious neurotrophic bioactivity for sensory neurons in the injured dorsal root ganglia.%背景:许旺细胞源神经营养因子是从许旺细胞胞浆中分离纯化出的一种活性蛋白质,能明显的维持脊髓前角运动神经元的存活和促进周围神经的再生.目的:观察许旺细胞源神经营养因子对周围神经高位损伤所致脊髓背根节感觉神经元死亡的保护作用.设计:随机对照动物实验. 单位:深圳市第二人民医院.材料:选用清洁级出生3周SD幼鼠30只,雌雄不拘.随机分为营养因子组和生理盐水对照组,各15只.两组动物均以左侧为正常侧,右侧为损伤侧.方法:实验于2003-05/2003-07在中山大学医学院实验动物中心完成.①两组大鼠均建立L4.5神经根高位离断动物模型,并将近侧神经残端与硅胶管吻接.根据分组,胶管内分别注入许旺细胞源神经营养因子(60 mg/L)或生理盐水各20 μL,凡士林封固硅胶管两端.②术后4周处死动物取材,观察损伤神经根背根节感觉神经元的存活率和形态学变化.主要观察指标:①两组鼠损伤侧坐骨神经再生情况大体观察.②两组鼠背根节神经元存活情况.③背根节神经元形态学变化.结果:30只鼠全部进入结果分析.①两组鼠坐骨神经再生情况大体观察:营养因子组神经新生轴突沿硅胶管生长,长度达1 cm;对照组新生轴突较细少,长度约0.8 cm.②两组鼠背根节神经元存活情况:营养因子组背根节内有少量纤维组织增生,神经元丢失不明显,存活率是91.8%,对照组背根节内纤维组织增生明显,神经元大量丢失,存活率是58.6%,营养因子组神经元存活率较对照组高33.2%(P＜0.01).③背根节神经元形态学变化:对照组背根节神经元的直径和面积显著低于营养因子组和正常侧[(21.8±1.4)μm,(373.1±50.9)μm2比(24.8±1.1)μm,(482.8±42.2)μm2和(24.5±1.3)μm,(471.5±51.4)μm2,P＜0.01],而营养因子组神经元直径和面积与正常侧相比差异无显著性(P＞0.05).结论:许旺细胞源神经营养因子对受损的背根节感觉神经元有明显的神经营养活性.
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