神经根撕脱后3种鼠类脊髓运动神经元的再生反应

背景臂丛撕脱损伤脊髓运动神经元的程度存在种属差异,神经元型一氧化氮合酶(Neuronalnitric oxide synthase,nNOS)基因与运动神经元的死亡密切相关.目的研究臂丛撕脱诱导受损运动神经元nNOS基因表达的种属差异.设计完全随机设计,对照实验研究.地点和材料中山大学动物实验中心提供实验所需SD大鼠、Hamster金黄地鼠、BALB/C小鼠各20只.干预3组动物分别行右侧臂丛撕脱术,2周后取C7段脊髓进行nNOS免疫细胞化学、NADPH-d酶组织化学和中性红活细胞染色.主要观察指标三种动物损伤侧脊髓前角nNOS阳性和存活的运动神经元数目.结果臂丛撕脱后2周,SD大鼠和金黄地鼠损伤侧前角都可见大量强阳性的nNOS运动神经元,而BALB/C小鼠却没有此反应.统计分析显示三组动物间nNOS阳性运动神经元数目有显著差异(F=501.502,P＜0.001)SD大鼠多于金黄地鼠(55.59%与42.26%,t=5.940,P＜0.001),多于BALB/C小鼠(55.59%与0%,t=51.651,P＜0.001),金黄地鼠多于BALB/C小鼠(42.26%与0%,t=21.452,P0.001);三组动物间存活的运动神经元数目也有显著差异(F=110.588,P＜0.001)SD大鼠多于金黄地鼠(87.29%与76.01%,t=5.252,P＜0.05),多于BAL/C小鼠(87.29%与57.38%,t=19.561,P<.001),金黄地鼠多于BALB/C小鼠(76.01%与57.38%,t=7.996,P＜0.001).结论臂丛撕脱后大鼠、金黄地鼠和小鼠nNOS表达的差异与损伤运动神经元死亡的种属差异密切相关,提示损伤诱导的nNOS基因表达可能参与受损运动神经元的再生反应.

Three species of animals regeneration response of spinal motoneurons following roots avulsion

BACKGROUND: There are species differences of motoneurons injury degree following roots avulsion and the nNOS gene expression is closely related to the death of motoneurons.OBJECTIVE: To study the diversity of nNOS gene expression in spinal motoneurons following roots avulsionDESIGN: Completely randomized design and control experiment.SETTING and MATERIALS: Twenty male Sprawgue-Dawley rats(200-250 g each), twenty BAL/C mice(20-25 g each) and twenty golden hamsters( 100 - 110 g each) were obtained from the Laboratory Animal Unit of Sun Yat-sen University.INTERVENTION: Avulsion was conducted at right brachial plexus. Two weeks later the C7 segments were separated for nNOS immunocytochemistry,NADPH-d enzyme histochemistry and neutral red staining.MAIN OUTCOME MEASURES: The number of nNOS-positive motoneurons and surviving motoneurons.RESULTS: Both neuronal NOS ICC and NADPH-diaphorase showed the same pattern of nNOS-positive neuron distribution in C7 spinal cords. Large amounts of the nNOS-positive motoneurons with high density were elicited in the lesion side of C7 anterior horns of both rats and hamsters. However, there was no nNOS expression detected in mice motoneurons. The difference of the nNOS-positive motoneurons among three different rodents was significant( F = 501. 502, P ＜ 0. 001 ). The number of nNOS-positive motoneurons was significantly higher in SD rats than in hamsters(55.59% vs 42.26%, t =5. 940, P ＜0.001) and than in mice(55. 59% vs0%,t=51.651, P ＜0.001), and it was also significantly higher in hamsters than in mice(42.26% vs 0% , t = 21. 452, P ＜ 0. 001 ). The difference of the surviving motoneurons among these three rodents was also significant( F =110. 588, P ＜ 0. 001 ) . The number of surviving motoneurons was significantly higher in SD rats than in hamsters(87.29% vs 76.01%, t = 5. 252,P ＜ 0.05) and than in mice(87.29% vs 57.38%, t=19.561, P ＜0. 001), and it was also significantly higher in hamsters than in mice(76.01% vs 57.38%,t=7.996, P ＜0.001).CONCLUSION: Species differences in injury-induced nNOS expressions are closely related to species differences in injured motoneurons death among rats, hamsters and mice following roots avulsion. This result supports the hypothesis that avulsion-induced nNOS in motoneurons may play a beneficial role in the regeneration of the injured motoneurons.