运动训练对椎间盘退变模型大鼠疼痛及细胞外基质合成的影响

Exercise effects on pain relief and extracellular matrix production in a rat model of intervertebral disc degeneration

背景:研究表明运动训练可促进健康大鼠椎间盘内细胞增殖、细胞外基质合成。对于已经退变的椎间盘,运动训练对其细胞增殖、细胞外基质合成是否同样具有促进作用?从而对其下腰痛产生影响?目的:探讨运动训练对退变模型大鼠椎间盘内细胞外基质合成的影响。方法:大鼠L5-6椎间盘注射完全弗氏佐剂制备椎间盘退变模型,术后休息2周以恢复创伤。随机分为2组,运动组大鼠每天进行跑步训练;而自然恢复组则只限于笼内自由活动。术后7,14,28,42,56,70 d进行行为学测试,并取材阿新蓝染色检测椎间盘内蛋白多糖水平,免疫组化染色检测蛋白聚糖和Ⅱ型胶原含量。结果与结论:(1)造模术后第7天与基线值比较,大鼠穿刺椎间盘所对应背部位置的压力阈值明显降低,而整理毛发和"湿狗摇动"等自发行为指标增多,差异有显著性意义(P<0.05);提示完全弗氏佐剂椎间盘内注射引起退变、诱发局部痛觉过敏和行为异常;(2)运动组大鼠在运动训练14 d后,背部压力阈值增加、"湿狗摇动"行为减少,且与自然恢复组比较差异有显著性意义(P<0.05),而整理毛发行为则在运动训练28 d后出现明显减少,与自然恢复组比较差异有显著性意义(P<0.01);提示运动训练可以减轻模型大鼠由椎间盘退变引起的疼痛;(3)术后第21天时,2组椎间盘髓核和纤维环中蛋白多糖、蛋白聚糖、Ⅱ型胶原含量均较基线值显著下降(P<0.01),提示完全弗氏佐剂注射节段椎间盘发生退变;(4)运动组大鼠在运动训练14 d后,髓核中蛋白多糖、蛋白聚糖、Ⅱ型胶原及纤维环中蛋白多糖含量明显增多,且与相应的自然恢复组比较差异均有显著性意义(P<0.01);经过8周的运动训练,运动组大鼠髓核和纤维环的蛋白多糖含量与自然恢复组比较约增加四至五倍,髓核中蛋白聚糖和Ⅱ型胶原约增加三至四倍;(5)综上所述,运动训练可以促进退变椎间盘内蛋白多糖、蛋白聚糖和Ⅱ型胶原等细胞外基质的合成。

BACKGROUND： Exercise has been proved to accelerate the proliferation of intervertebral disc cells and extracellular matrix production in healthy rats. For the degenerative intervertebral disc, whether exercise also has positive effects on its cell proliferation, extracellular matrix production or pain relief remains unclear. OBJECTIVE： To investigate the effect of exercise on the extracellular matrix production in a rat model of intervertebral disc degeneration. METHODS： A rat model of intervertebral disc degeneration was prepared by Freund＇s complete adjuvant injection into the intervertebral disc at L5-6 levels. Then, the model rats were allowed to have a rest for 2 weeks. All rats were then randomly divided into exercise and control groups. Rats in the exercise group were forced to run every day, while the controls allowed free activities in the cage. The behavioral tests were performed at 7, 14, 28, 42, 56 and 70 days after modeling; meanwhile, the intervertebral disc samples were collected used for alcian blue staining and immunohistochemical staining to detect the levels of proteoglycan, aggrecan and collagen type II in the intervertebral disc cells, respectively. RESULTS AND CONCLUSION： Vocalization threshold on the rat back of punctured disc was significantly decreased, while grooming and wet-dog shaking were significantly increased at 7 days after modeling compared with the baseline（P〈0.05）, suggesting that Freund＇s complete adjuvant injection successfully induces disc degeneration, hyperalgesia and abnormal behaviors. Further, the vocalization threshold and wet-dog shaking in the exercise group showed significant improvement compared with the control group after 14 days of exercise（P〈0.05）, while the grooming was significantly reduced until the 28 th day（P〈0.01）, indicating that exercise can alleviate pain caused by disc degeneration in model rats. At 21 days after modeling, the levels of proteoglycan, aggrecan and collagen type II in the nucleus pulposus and annulus fibrosus were significantly decreased compared with the baseline（P〈0.01）, indicating the occurrence of disc degeneration. After 14 days of training, the levels of proteoglycan, aggrecan, and collagen type II in the nucleus pulposus and annulus fibrosus in the exercise group were significantly increased compared with the control group（P〈0.01）. Moreover, after 8-week exercise, the level of proteoglycan in the nucleus pulposus and annulus fibrosus in the exercise group was increased by 4-5 times compared with the control group, and levels of aggrecan and collagen type II in the nucleus pulposus in the exercise group also was increased by 3-4 times compared with the control group. To conclude, exercise can promote extracellular matrix increased by production by increasing the levels of proteoglycan, aggrecan, and collagen type II in the degenerative intervertebral disc.