Effect of electrical stimulation on local microvessel regeneration and expression of plasma endothelin-1 and nitric oxide in a rat model of myofascial trigger points / 中国组织工程研究

ABSTRACT

BACKGROUND: Plenty of evidences have revealed that electrical stimulation (ES) can promote local tissue vascular regeneration and regulate the expression of vasoactive substances, but it is unclear whether ES may promote local revascularization and change blood flow state in myofascial trigger points (MTrPs) or not. OBJECTIVE: To investigate the effect of ES on microvascular regeneration and plasma endothelin-1 and nitric oxide levels in MTrPs. METHODS: Fifty-four Sprague-Dawley rats were randomly divided into blank control, model and ES groups, with 18 rats in each group. And each group was equally subdivided into three subgroups (before, 7 and 15 days after intervention). In the model and ES groups, the rat model of MTrPs was established using combat and eccentric motion. Once the MTrPs model was made, the ES group was given ES intervention (depth 2 mm, voltage 6 V, frequency 20 Hz, pulse width 160 ms) at MTrPs, 30 minutes per day, for 15 days. Six rats from each group were executed at 7 and 15 days of intervention. Paraffin sections were manufactured for hematoxylin-eosin and immunohistochemical staining after the local tissues of MTrPs were dissected and separated. Subsequently, pathological changes were observed under light microscope. Microvessel density was counted and analyzed. The levels of plasma endothelin-1 and nitric oxide were detected by ELISA. The study protocol was approved by the Experimental Animal Ethics Committee of the Nanfang Hospital of Southern Medical University in China. RESULTS AND CONCLUSION: The changes of brittleness and insect-likes erosion in local MTrps tissues were observed under the light microscope in the model and ES groups. The micro-vessel density in MTrps increased and the tissue structure of MTrps gradually returned to be normal after ES intervention. The microvessel density in the model and ES groups was lower than that in the blank control group before intervention, but the microvessel density in the ES group was significantly higher than that in the other two groups at 7 and 15 days of intervention (both P 0.05). The levels of plasma endothelin-1 and nitric oxide were higher in the model and ES groups than the blank control group before intervention. After 15 days of intervention, the levels of plasma endothelin-1 in the ES group were decreased (P 0.05). These results reveal that ES intervention can promote the regeneration of microvessels and regulate the expression of vasoactive substances in MTrPs tissue, improve ischemia and hypoxia state of MTrPs and contribute greatly to local tissue repair.