大鼠脊髓挤压伤后小胶质细胞Toll样受体4表达的变化

目的探讨脊髓挤压伤后各时间点小胶质细胞Toll样受体4(TLR4)的表达变化及其与损伤面积和免疫球蛋白G渗出范围的关系。方法 48只成年雄性SD大鼠建立T8节段脊髓挤压伤模型,随机分为6组,每组8只;假手术对照组及挤压伤组动物在手术后0h、3h、24h、72h和7d用4%多聚甲醛灌注固定,取以挤压点为中心的2cm脊髓,冷冻切片后进行HE染色和免疫荧光染色,分别观察损伤面积的变化,TLR4表达和TLR4阳性小胶质细胞的分布,以及与血浆免疫球蛋白G(IgG)渗出范围的比较,并用IPP6.0软件计算各组的阳性数目。结果脊髓损伤后TLR4主要表达在小胶质细胞,在3～24h之间开始表达,伤后在72h达到高峰,7d时已经显著下降。阳性小胶质细胞的分布与IgG渗出范围一致。结论大鼠脊髓挤压伤模型中,表达在脊髓小胶质细胞上的TLR4可在脊髓继发性损伤中发挥重要作用,并与血脊髓屏障开放有关。

Change of Toll-like receptor 4 expression in microglial cells after spinal cord compression injury in rats

Objective To explore the change of Toll-like receptor 4(TLR4) expression in microglia after compression injury in the spinal cord of rats, and to compare the distribution of TLR4 positive cells with the area of injury and immunoglobulin G (IgG) extravasation at different time points. Methods Spinal cord compression injury was made at T8 segment in 48 adult male SD rats, and the rats were randomly divided into 6 groups. Sham and injured animals were fixed by perfusion of 4% paraformaldehyde, 2 cm of the spinal cord blocks with compressed site in center were then removed at 0 hour, 3 hours, 24 hours, 72 hours and 7 days after injury. Frozen sections were made for HE and immunofluoresent staining to detect the injury area and the expression of TLR4 in the spinal cord. The distribution of TLR4 positive cells, the injury area and the extravasated IgG were compared as well. The number of TLR4 positive microglial cells was counted by using Image Pro Plus 6.0 software. BR> Results TLR4 was mainly expressed in microglial cells and the expression started to increase between 3 hours and 24 hours, and peaked at 72 hours after the spinal cord compression injury, then descended at 7days, according to the number of TLR4-positive microglia. The distribution of TLR4 immunoreactive product was consistent with the area of injury and that of extravasated IgG. Conclusion In the rat model of spinal cord compression injury, TLR4 expressed in microglial cells may play an important role in the secondary injury and TLR4 expression may associate with the compromise of blood-spinal cord barrier. BR>