大鼠骨骼肌缺血后MMP-9的变化与骨骼肌损伤和重塑的关系

The modification of MMP-9 in rat skeletal muscle ischemia and the relationship between MMP-9 and muscular injury and remolding

目的建立单一骨骼肌部分缺血损害动物模型,并观察骨骼肌缺血后基质蛋白酶9(MMP-9)的表达与骨骼肌重塑的关系。方法解剖组:解剖新鲜Wistar大鼠后肢20只20侧,进行血管灌注,观测肌肉血管及神经走行。实验组:Wistar大鼠40只,随机均分为5组,正常对照组(A组)不经缺血处理;缺血1 d组(B组);缺血3 d组(C组);缺血5 d组(D组);缺血7 d组(E组)。观察肌纤维横截面和肌细胞坏死程度,测定腓肠肌肌肉重量、毛细血管密度,Western blot法检测MMP-9的表达。结果大鼠小腿三头肌血供丰富,腓肠肌内侧头血管相对独立。与A组比较,B组肌纤维横切面直径无明显变化,C、D、E组显著减小。肌肉毛细血管密度呈时间依赖性,随时间延长肌肉毛细血管密度明显下降,后逐渐增加。与A组比较,B组肌肉重量无明显变化,C组明显减轻,D组重量显著增加,E组重量下降到A组水平。细胞因子MMP-9变化呈时间依赖性,其表达与毛细血管密度变化平行。骨骼肌缺血导致MMP-9水平下降,而修复时MMP-9升高。结论大鼠小腿三头肌血供丰富,为腓肠肌缺血后损害的评价提供了解剖学基础。骨骼肌缺血后,肌纤维功能损伤呈时间依赖性加重,缺血一定时间后肌纤维逐渐修复。骨骼肌修复和新毛细血管生成有关。

Objective To observe the changes of matrix metalloproteinase-9 in early stage of skeletal muscle ische- mia and to analyze its correlation with skeletal muscle injury and remodeling by creating a single skeletal muscle is- chemia animal model with dissecting triceps surae of rats. Methods 60 Wistar rats were divided into anatomic group and experimental group. 20 sides of fresh hindlimbs of 20 Wistar rats in the anatomic group were dessected and vascular arterial perfusion were given, then the following items were observed： muscle shape, blood vessel, nerve shape, muscle fiber shape. The other 40 Wistar rats were divided into 5 groups （ n = 8 ） ： normal control group and four（ 1,3,5 and 7 d） ischemia groups marked A ,B ,C, D ,E. Models were made through anterior medical approach with rat hindlimbs. Muscle fiber cross-sectional and muscle cell necrosis degree were observed under mi- croscope by staining with hematoxylin and eosin. Gastrocnemius muscle weight and gastrocnemius muscle capillary density were detected. Western blot was also conducted to examine the expression of MMP-9. Results 1Triceps surae of rat had rich blood supply. The transverse section diameter of muscle fibers in group A was the same in group B, and decreased significantly in C, D, E groups. The modification of capillary density was time-dependent. The weight of muscle decreased in group C, and was at the same level in group A, B, E, but increased significantly in group D. The alteration of expression of cytokine was complex：the levels of MMP-9 decreased and was time-de- pendent, and the detection results of MMP-9 changes showed that they were same with the capillary density in a se- quence. Conclusion Triceps surae of rat has rich blood supply. The study of injury of limb function evaluation af- ter ischemia of the medial head of the gastrocnemius muscle provides an anatomical basis. The injury in skeletal muscle ischemia is time-dependent, and the restoration after isehemia maybe due to the capillary density. The ex- pression of MMP-9 decreases after ischemia and increases during the restoration. The MMP-9 can promote the func- tion of skeletal muscle. The inflammation induces the changes of muscle weight after ischemia.