本研究构建急性大鼠脊髓夹伤模型, 并将大鼠随机分为单纯脊髓损伤对照组及脊髓损伤联合弱激光照射组。照射组应用810 nm波长, 150 mW照射功率, 照射光斑0.3 cm2的弱激光对脊髓损伤区进行经皮照射, 连续照射3天, 7天或14天。应用免疫荧光、免疫印迹实验方法, 测定脊髓损伤区巨噬细胞及小胶质细胞的极化表达。应用酶联免疫吸附法测定脊髓损伤区白细胞介素4的表达情况。应用坚牢蓝髓鞘染色测定两组损伤脊髓中髓鞘保留的差异。采用BBB评分对两组大鼠后肢运动功能的恢复进行评估。结果表明, 810 nm弱激光对脊髓损伤区连续照射3天, 7天后, 可显著减少M1型巨噬细胞及其标志物诱导型一氧化氮合酶的表达, 在7天时间增加M2型巨噬细胞及其标志物精氨酸酶1的表达。弱激光照射组白细胞介素4的表达明显增加。损伤后14天, 弱激光照射组脊髓损伤区髓鞘保留面积比值明显提高。损伤后7天及14天时, 弱激光照射组大鼠的BBB评分明显升高。该实验结果表明, 810 nm弱激光经皮照射, 可增加大鼠急性脊髓损伤区M2型巨噬细胞及小胶质细胞的表达, 并减少脊髓损伤后的髓鞘脱失, 促进脊髓损伤大鼠运动功能的恢复。

The present study was designed to establish a bilateral compression spinal cord injury SCI rat model. 42 SD rats were randomly assigned to SCI only group (control group) or SCI followed by low level laser therapy group (LLLT group). After SCI, for the LLLT group, rats were received a laser beam (810 nm wavelength, 150 mW output power, 0.3 cm2 light spot) in percutaneous method once daily for consecutive 3, 7 or 14 days. Immunofluorescence (IF) and western blot (WB) were performed to evaluate the polarization state of macrophage/microglia in the injured spinal cord. Meanwhile, enzyme linked immunosorbent assay (ELISA) was performed to assess the expression of interleukin 4 (IL-4) and luxol fast blue (LFB) staining was used to assess the preservation of myelin sheath. Results of IF and WB revealed that M1 subset of macrophage/microglia and the cell marker inducible nitric oxide synthase(INOS) were significantly reduced in LLLT group at 3 and 7 days post injury (dpi). M2 subset and expression of the cell marker “arginasel(Arg1)” were significantly higher at 7 dpi. Expression of IL-4 was significantly higher in LLLT group. Preservation of myelin sheath and BBB scores were significantly higher in LLLT group at 14dpi and 7,14dpi respectively. The present study indicates that low level laser therapy can promote the beneficial M2 macrophage/microglia polarization, reduce the demyelination and accelerate locomotor functional recovery after spinal cord injury in rats.