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目的 观察大鼠上运动神经元损伤后 ,骨骼肌乙酰胆碱受体γ亚单位和ε亚单位mRNA的变化以及脊髓前角降钙素基因相关肽的变化。方法 选用成年雄性Wistar大鼠 ,戊巴比妥钠麻醉下于下胸段行脊髓横断术 ,术后分别于 0、1、2、4、7和 14d取材横断水平以下的脊髓和下肢腓肠肌。应用Northern杂交方法测定肌肉中乙酰胆碱受体γ亚单位和ε亚单位mRNA的含量 ,应用放射性免疫方法测定脊髓前角降钙素基因相关肽的含量。结果 肌肉中乙酰胆碱受体γ亚单位mRNA自术后第 4d起与正常值比较显著性提高 ,14d时达到最高值 ;而ε亚单位mRNA直至术后 14d才与正常值的差异有统计学意义。脊髓前角降钙素基因相关肽的含量术后即减少 ,自术后第 2d起降至正常水平的 5 0 %～ 80 %。结论 上运动神经无损伤后 ,肌肉中乙酰胆碱受体γ和ε亚单位mRNA的含量显著增加 ,降钙素基因相关肽对γ和ε亚单位的表达可能有调控作用。
Objective To observe the changes of acetylcholine receptor γ subunit mRNA and ε subunit mRNA and the changes of calcitonin gene related peptide in spinal cord anterior horn after injury of motor neurons in rats. Methods Adult male Wistar rats were anesthetized with sodium pentobarbital and underwent spinal cord transection in the lower thoracic segment. The spinal cord and lower limb gastrocnemius were transected at 0, 1, 2, 4, 7 and 14 days after operation respectively. The contents of acetylcholine receptor gamma subunit and epsilon subunit mRNA in muscle were determined by Northern hybridization. The content of calcitonin gene-related peptide in spinal cord anterior horn was measured by radioimmunoassay. Results The muscle mRNA expression of acetylcholine receptor γ subunit mRNA increased significantly from the 4th day after operation and reached its maximum at 14 days. However, the mRNA level of ε subunit was not significantly different from the normal value at 14 days postoperatively. The content of calcitonin gene-related peptide in the anterior horn of the spinal cord decreased after the surgery and dropped to 50% -80% of the normal level from the 2nd day after the operation. Conclusions The content of acetylcholine receptor gamma and epsilon subunit mRNA in muscle increased significantly after injury of upper motor nerve and the expression of gamma and epsilon subunit may be regulated by calcitonin gene related peptide.