| Spinal cord injury could induce the loss of neuronal function directly, and has a highincidence of disability and mortality. The treatment and functional recovery after spinalcord injury (SCI) is a worldwide problem unsolved. Up to now, there is no other treatmentto be chosen from except a high amount of glucocorticosteroid such as Prednol exerted in8hours after injury. It comes to be a new physical treatment or low-level laser therapybecause of the biostimulating effects after low-level laser irradiated on biological tissues.Nowadays, low-level laser therapy has been adopted by a lot of clinical departments likedepartment of acupuncture and moxibustion and department of physiotherapy and has gota great number of satisfactory results. Low-level laser irradiation therapy in the treatmentof peripheral nerve injury has obtained the ideal effect that it could improve theregeneration of neural axons and functional recovery after peripheral nerve injury.However, there was little research in the repair of SCI. More and more researchers havethought that whether low-level laser therapy applied on central nervous system such as spinal cord injury could improve the recovery too. For the past few years, bothlaboratories abroad and our group had reported that low-level laser irradiation appliedpercutaneously could improve the functional recovery of SCI rats. But none had explainedthe mechanism of low-level laser repair effect on SCI. As we all know, the procedureinducing injury after SCI includes two steps, namely the primary injury and secondaryinjury. Though the lesion induced by primary injury is unreversed, the secondary injurycould be relieved and reversed. Aimed at finding out the influence of low-lever lasertherapy on secondary inflammatory reaction at the early stage of SCI and the formation ofglial scar at the recovery stage we designed and commenced two experiments as follows.There are two parts in our research.Part IAcute spinal cord injury rat model was established by Allen’s method and explore theeffect of810nm low-level laser irradiation on expression of TNF-α，IL-6and IL-10inacute spinal cord injury.Method:68SD rats were randomly divided into normal group, SCI group and Lasergroup. Spinal cord injury model was created by Allen’s method. Light (810nm,150mW)was applied transcutaneously at the lesion site of rats in Laser group. Functional recoverywas assessed by open-field test (BBB test) on1d,3d,7d after injury. The expression ofTNF-α, IL-6and IL-10in the injured spinal cords were examined by ELISA method at thetime of1h,3h,6h,12h,1d,3d,5d and7d after injury.Results: We found that there was a statistically significant functional recovery(P<0.05) in the Laser group compared to SCI group at7d. The expression of TNF-α andIL-6of Laser group was significantly lower than the comparable SCI group at the time of6h,12h,1d (TNF-α) and6h,12h,5d (IL-6)(P<0.05). The expression of IL-10of Lasergroup was significantly higher than the comparable SCI group at the time of1d,3d,5dand7d (P<0.05). There was no statistical difference at other time point.Conclusion: The results of our study showed that laser irradiation can effectivelyinhibit the expression of pro-inflammatory cytokine TNF-α and IL-6and significantlypromote the expression of IL-10in rats of acute spinal cord injuries. And Laser irradiation can promote functional recovery of acute spinal cord injury rats.Part IIEvaluate the functional recovery after spinal cord injury in rats after low-level laserirradiation therapy and detect the influence of expression of NG2and GAP-43afterirradiated.Method: Rats with acute spinal cord contused injury were irradiated by low-levellaser for2997s daily and21days consecutively. Animals’ functional recoveries wereestimated with BBB score scales combined with footprint analysis every week. Theconductive ability of spinal cord tract was revealed by motor evoked potentials. The cavityvolume was measured after section-staining with HE. Western blot and real-timefluorescent quantitation PCR analysis were used to quantify the expression andtranscription of NG2and GAP-43in injured spinal cord tissues.Results: From BBB scores and footprint analysis, the rats irradiated with low-levellaser behaved conspicuous improvement of the motor function of hindlimbs in7,14and21days. There was statistical encouragement of conductive ability after irradiating. Bothof the macropathology and H/E staining showed extenuating damage with dimished cavityvolume. The transcription and expression of NG2proteoglycan were statistically downregulated and GAP-43up regulated in7,14and21days after injury.Conclusion: Present findings suggest that810nm low-level laser irradiation therapymay down regulate the expression of NG2after injury, improve functional recovery of ratsand could be used as an combined therapeutic method on SCI patients. |
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