大鼠脊神经前根切断后脊髓内Slit1表达的变化

Changes of Slit1 expression in spinal cord after the section of dorsal root in rats

目的 ：探讨脊神经前根损伤后,大鼠脊髓组织中Slit1的表达变化,为进一步研究Slit1在神经再生中的作用提供依据。方法：应用2月龄SD大鼠共100只,体重250±20g,其中80只SD大鼠实施左侧L5及L6脊神经前根切断,分别在伤后1d、3d、7d、14d时处死（每个时间点20只）,取L5～L6脊髓节段,标记左右;左侧半L5～L6脊髓节段为实验组;右侧半为自身对照组。假手术大鼠（20只）实施麻醉及暴露L5及L6脊神经手术,未行L5及L6脊神经前根切断术,取其L5～L6脊髓节段为空白对照组。采用免疫组化、Western blotting及RT-PCR法检测大鼠脊髓组织中Slit1的变化。结果：脊神经前根切断后1d、3d、7d、14d,实验组中Slit1阳性细胞数分别为5.78±1.53、15.85±2.65、23.93±1.53、8.78±1.78;自身对照组中分别为2.31±1.63、2.57±1.89、3.20±2.16、3.02±2.15。各时间点实验组中Slit1阳性细胞数显著高于空白对照组（2.89±1.26）及自身对照组（P〈0.05）。Western blotting示脊神经前根切断后1d、3d、7d、14d,实验组Slit1相对表达量分别为0.326±0.09、0.448±0.05、0.638±0.07、0.304±0.07;自身对照组分别为0.038±0.02、0.038±0.01、0.035±0.02、0.046±0.03。各时间点实验组Slit1相对表达量与空白对照组（0.038±0.03）及自身对照组比较,差异有显著性（P〈0.05）。RT-PCR示脊神经前根切断后1d、3d、7d、14d,实验组Slit1 m RNA相对量分别为0.380±0.03、0.425±0.04、0.768±0.05、0.605±0.04;自身对照组分别为0.210±0.04、0.265±0.03、0.292±0.02、0.261±0.02。各时间点实验组Slit1 m RNA相对量与空白对照组（0.231±0.03）及自身对照组比较,差异有显著性（P〈0.05）。结论 ：脊神经前根切断后,同侧脊髓灰质前角内Slit1的表达显著增加。

Objectives： To investigate the changes of Slit1 expression in spinal cord after the section of dorsal root in rats, and to provide evidence for the role of Slit1 in nerve regeneration. Methods： The left dorsal roots of L5 and L6 spinal nerve were transected from 80 2-month-old Sprague-Dawley rats, and the changes of Slit1 expression were detected with RT-PCR, Western blotting and immunohistochemical methods in the related spinal cord at 1d, 3d, 7d and 14 d, respectively. The left halves of these L5/6 spinal cords were included in test group, the right halves of these L5/6 spinal cords were included in self-control group and the L5/6spinal cords from sham operation rats（which were anaesthetized and the L5 and L6 spinal nerves were exposed, but without section operation, n =20） in blank control group. Then the number of Slit1 positive cells and the average integral optical density value（AIODV） were determined with image analysis. Results： The numbers of Slit1 positive cells in test group at 1d, 3d, 7d and 14 d were 5.78±1.53, 15.85±2.65, 23.93±1.53 and 8.78±1.78; the numbers in self-control group were 2.31±1.63, 2.57±1.89, 3.20±2.16 and 3.02±2.15, respectively. The number of Slit1 positive cells in test group was significantly higher than that in blank control groups（2.89 ±1.26） or that in self-control group（P 0.05）. Western blotting showed the relative expressions of Slit1 in test group at 1d, 3d, 7d and 14 d were 0.326 ±0.09, 0.448 ±0.05, 0.638 ±0.07 and 0.304 ±0.07; the numbers in self-control group were 0.038 ±0.02, 0.038 ±0.01, 0.035 ±0.02 and 0.046 ±0.03 respectively. Compared with blank control group（0.038±0.03） and self-control group, the relative expression of Slit1 in test group were significant（P〈0.05）. RT-PCR showed the relative expressions of Slit1 m RNA in test group at 1d,3d, 7d and 14 d were 0.380±0.03, 0.425±0.04, 0.768±0.05 and 0.605±0.04; the numbers in self-control group were 0.210±0.04, 0.265±0.03, 0.292±0.02 and 0.261±0.02 respectively. Compared with blank control group（0.231±0.03） and self-control group, the relative expression of Slit1 m RNA in test group was significantly higher（P〈0.05）. Conclusions： After the section of dorsal root, Slit1 expression in spinal cord is significantly up-regulated.