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, 14 (1), 57-64
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Low-Level Laser Irradiation Improves Motor Recovery After Contusive Spinal Cord Injury in Rats

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Low-Level Laser Irradiation Improves Motor Recovery After Contusive Spinal Cord Injury in Rats

Junesun Kim et al. Tissue Eng Regen Med.

Abstract

This study investigated the therapeutic effects of low-level laser irradiation (LLLI) on the recovery of motor function and its underlying mechanisms in rats with spinal cord injury (SCI). The spinal cord was contused at the T11 level using a New York University impactor. Thirty-eight rats were randomly divided into four groups: LLLI with 0.08 J, 0.4 J, 0.8 J, and sham. We transcutaneously applied at the lesion site of the spinal contusive rats 5 min after injury and then daily for 21 days. The Basso, Beattie and Bresnahan (BBB) locomotor scale and combined behavioral score (CBS) were used to evaluate motor function. The spinal segments of rostral and caudal from the lesion site, the epicenter, and L4-5 were collected from normal and the all groups at 7 days after SCI. The expression of tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) was compared across groups in all regions. In the present study, LLLI with 0.4 J and 0.8 J led to a significant improvement in motor function compared to sham LLLI, which significantly decreased TNF-α expression at the lesion epicenter and reduced iNOS expression in the caudal segment for all LLLI groups and in the L4-5 segments for the 0.4 J and 0.8 J groups when compared to sham LLLI group. Our results demonstrate that transcutaneous LLLI modulate inflammatory mediators to enhance motor function recovery after SCI. Thus, LLLI in acute phase after SCI might have therapeutic potential for neuroprotection and restoration of motor function following SCI.

Keywords: Low-level laser irradiation; Motor recovery; Post-traumatic inflammation; Secondary injury; Spinal cord injury.

Conflict of interest statement

The author(s) declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.All animal protocols in this study were approved by the Korea University Institutional Animal Care and Use Committee (KUIACUC-2010-170).

Figures

Fig. 1
Fig. 1
Effects of LLLI on motor function. A Changes in locomotor function after LLLI (BBB score). In the 0.8 J group, locomotor function recovered significantly from days 4 to 35 after SCI, except on days 10. BBB scores for the 0.4 J group significantly increased from days 4 to 35 after SCI, except from days 7 to 10. *P < 0.05. B Changes in combined behavioral score after LLLI. CBS in the 0.8 J group was significantly lower on days 4, 21, 28, and 35 after SCI than the sham group. *P < 0.05. All data are expressed as mean ± SEM
Fig. 2
Fig. 2
Change of spinal TNF-a protein expression in the spinal cord after LLLI treatment following SCI. A Representative western blots: a comparison of TNF-α expression in rostral, epicenter, caudal, and L4–5 segments in each group (n = 5/each group). B A quantitative graph for TNF-α protein expression. A line presents the basal level of TNF-α detected in the equivalent segment of the spinal cord of a normal rat. LLLI significantly reduced TNF-α expression in the lesion epicenter compared with the sham group. *P < 0.05. All data are expressed as mean ± SEM
Fig. 3
Fig. 3
Change of spinal iNOS protein expression in the spinal cord after LLLI treatment following SCI. A Representative western blots: a comparison of iNOS expression in rostral, epicenter, caudal, and L4–5 segments in each group (n = 5/each group). B A quantitative graph for iNOS protein expression. A dot line presents the basal level of iNOS detected in the equivalent segment of the spinal cord of a normal rat. LLLI significantly reduced the expression of iNOS in the rostral, caudal, and L4–5 segments compared with the sham group. *P < 0.05. All data are expressed as mean ± SEM

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