A型肉毒毒素一侧椎旁肌注射建立双足直立鼠脊柱侧凸模型的初步研究

Injection of Botulinum toxin A into unilateral paraspinal muscles to establish scoliosis model in immature bipedal rats

目的:探讨应用A型肉毒毒素(BTX-A)建立双足直立鼠脊柱侧凸模型的可行性。方法:将56只4周龄雌性SD大鼠随机分为A、B、C、D、E、F、G组,每组8只。将所有大鼠截除双前肢,予高笼喂养,建立双足直立鼠模型,同时行全脊柱前后位X线片检查,剔除存在脊柱侧凸的大鼠,并及时补充。截肢后3d,A^F组大鼠于胸椎后凸区域右侧椎旁肌多点注射BTX-A,注射剂量分别为100U、50U、25U、12.5U、6.25U、3.125U,注射体积为0.5ml,G组注射等体积生理盐水。注射后2周,存活大鼠行全脊柱前后位X线片检查,明确各组大鼠是否存在脊柱侧凸,若脊柱向右侧侧凸成角定义为正值,若脊柱向左侧侧凸成角定义为负值;麻醉下切开背部皮肤,肉眼观察大鼠背部肌肉形态变化,留取注射区域椎旁肌标本行组织学检查。结果:双足直立鼠模型全部建立成功,大鼠麻醉苏醒后可竖直站立取水。A^D组大鼠于BTX-A注射后5d内相继死亡,E、F、G组大鼠全部存活。注射后2周全脊柱前后位X线片检查,E、F组大鼠均存在脊柱侧凸,且注射侧为凸侧,E组侧凸Cobb角为37.5°~46.8°,平均(41.9±3.4)°;F组为28.3°~37.3°,平均(33.1±3.2)°;G组侧凸Cobb角为-8.2°~12.0°,平均(2.9±6.8)°;E、F、G组两两比较均有统计学差异(P<0.05)。注射后2周,E、F组大鼠切开背部皮肤,见大鼠脊柱向注射侧侧凸,肉眼及光镜下见注射BTX-A区域的椎旁肌明显萎缩;G组肌肉无明显变化。结论:BTX-A 6.25U及3.125U一侧椎旁肌注射可建立双足直立鼠脊柱侧凸模型,椎旁肌肌力失衡可导致双足直立鼠脊柱侧凸发生。

Objectives： To discuss the feasibility and efficacy of injection of Botulinum toxin A into unilateral paraspinal muscles to establish scoliosis model in immature bipedal rats. Methods： 56 4-week old female SD rats were divided into 7 groups randomly. All rats underwent amputations of forelimbs under anesthesia and were kept in height-regulated cages. Group A-F received different concentrations of BTX-A respectively （100U, 50U, 25U, 12.5U, 6.25U, 3.125U, all in 0.5ml）. Group G only received an injection of same amount of normal saline. 2 weeks after injection, AP X-rays were obtained under anesthesia. The rats were cut off the skin on the back. Naked-eye observations were taken. Morphological changes of paravertebral muscles were detected under light microscope. Results： The rats were observed to be able to stand bipedally immediately after the amputations of forelimbs. After BTX-A injection, the rats in group A-D were all dead, while all rats in group E, F and G survived. 2 weeks after injection, AP X-rays showed that all survived rats had developed seoliosis in group E and F, and all curves had convex towards right side. The mean Cobb angle in group E was （41,9±3.4）° at 2 weeks after injection, and the mean Cobb angle in group. F and G was （33.1±3.2）° and （2,9±6.8）° respectively. Naked-eye observations showed muscle atrophy on the convex side. The histologieal findings revealed the same as naked-eye observation. Those were not observed in group G. Conclusions： Scoliosis model can be created by 6.25U or 3.125U BTX-A injection in immature bipedal rats, which indicates that paravertebral muscle imbalance can induce seoliosis.