Abstract
The effects of low-level laser therapy (LLLT) and natural latex protein (F1, Hevea brasiliensis) were evaluated on crush-type injuries (15kg) to the sciatic nerve in the expressions of nerve growth factor (NGF) and vascular endothelium growth factor (VEGF) and ultrastructural morphology to associate with previous morphometric data using the same protocol of injury and treatment. Thirty-six male rats were allocated into six experimental groups (n = 6): 1-Control; 2-Exposed nerve; 3-Injured nerve; 4-LLLT (15J/cm2, 780nm, 30mW, Continuous Wave) treated injured nerve; 5-F1 (0,1mg) treated injured nerve; and 6-LLLT&F1 treated injured nerve. Four or eight weeks after, sciatic nerve samples were processed for analysis. NGF expression were higher (p<0.05) four weeks after in all injured groups in comparison to Control (Med:0.8; Q1:0; Q3:55.5%area). Among them, the Injured (Med:70.7; Q1:64.4; Q3:77.5%area) showed the highest expression, and F1 (Med:17.3; Q1:14.1; Q3:21.7%area) had the lowest. At week 8, NGF expressions decreased in the injured groups. VEGF was expressed in all groups; its higher expression was observed in the injured groups 4 weeks after (Injured. Med:29.5; F1. Med:17.7 and LLLT&F1. Med:19.4%area). At week 8, a general reduction of VEGF expression was noted, remaining higher in F1 (Med:35.1; Q1.30.6; Q3.39.6%area) and LLLT&F1 (Med:18.5; Q1:16; Q3:25%area). Ultrastructural morphology revealed improvements in the treated groups; 4 weeks after, the F1 group presented greater quantity and diameter of the nerve fibers uniformly distributed. Eight weeks after, the F1 and LLLT&F1 showed similar characteristics to the non-injured groups. In summary, these results and our previous studies indicated that F1 and LLLT may favorably influence the healing of nerve crush injury. Four weeks after nerve injury F1 group showed the best results suggesting recovery acceleration; at 8th week F1 and LLLT&F1 groups presented better features and higher vascularization that could be associated with VEGF maintenance.
Highlights
Nerves constitute the functional part of the peripheral nervous system (PNS) formed by fascicles of myelinated and unmyelinated nerve fibers, composed of motor, sensory and autonomic portions [1, 2]
The F1 protein group was the only group submitted to nerve injury that presented lower immunoreactivity compared to the other injured groups (Injury, level laser therapy (LLLT) and level laser and Latex F1 Protein group (LLLT&F1)) in this period of analysis, with similar values of the Exposed group (p > 0.05)
The present study analyzed the expressions of the nerve growth factor (NGF) and vascular endothelium growth factor (VEGF) growth factors and the ultrastructural morphology of the sciatic nerve after a crush injury and subsequent treatment with LLLT and F1 protein, in order to improve the understanding of the action of these agents and establish a relationship with our previous morphometric studies [21, 22, 24]
Summary
Nerves constitute the functional part of the peripheral nervous system (PNS) formed by fascicles of myelinated and unmyelinated nerve fibers, composed of motor, sensory and autonomic portions [1, 2]. 100,000 patients are submitted to surgery annually to recover peripheral nerves in the U.S.A. and Europe. These injuries have a strong negative impact on the quality of life of the population, resulting in paralysis, anesthesia, lack of control and painful neuropathy. Peripheral nerve fibers have considerable potential for regeneration, spontaneous recovery is generally poor and may result in sequelae, especially in the case of large nerve defects [1, 3,4,5,6,7]. Stimulation systems, biological stimuli and physical stimuli have shown encouraging results in the regeneration of peripheral nerves [3]
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