胰岛素样生长因子局部注射对眼外肌作用的实验研究

Study of extraocular muscle with direct injection of insulin-like growth factorⅠ

目的 探讨局部注射胰岛素样生长因子（insulin-like growth factor-Ⅰ,IGF-Ⅰ）对成年兔眼外肌的作用及机制.方法 7只成年新西兰大白兔,双眼上直肌随机注射0.05ml（10靏）IGF-Ⅰ或0.05ml生理盐水,1周后肌肉张力换能器检测上直肌肌肉力量,获取上直肌行组织学检查.结果 实验组上直肌单刺激收缩力为（2.4515±1.1019）mN,对照组上直肌为（1.1511±0.6755）mN,差异有统计学意义（t =2.58,P =0.049）,实验组上直肌各刺激频率的强直收缩力比对照组明显更大,均有显著性差别.实验组单位重量肌肉的收缩力比对照组更大,各刺激频率均有显著性差异.实验组上直肌横截面面积为（10.04±2.52）mm2较对照组（7.79±1.85） mm2明显更大,差异有统计学意义（t =2.84,P =0.047）;实验组上直肌中活化的卫星细胞为（30.63±6.76）%,比对照组（17.07±5.36）%显著更高（t =8.73,P =0.000）.结论 成年动物眼外肌局部注射IGF-Ⅰ能快速、显著提高肌肉收缩力;肌肉横截面增加、肌纤维周径变大、卫星细胞活化增加.

Objective To evaluate the effects on muscle mass and force generation of IGF-I injection in adult rabbit superior rectus muscle. Methods One superior rectus muscle in normal adult rabbits received a single injection of 10ug （0.05ml） IGF-I, and the contralateral muscle received an injection of 0.05ml saline only. One week after injection, muscle force and muscle morphology were studied both in IGF treated and control muscles. Results In the treated muscles, the mean single-twitch force generation was 2.4515＋1.1019mN compared with 1.1511＋0.6755mN （t =2.58, P =0.049） in control muscles. Mean titanic force generation was increased significantly at all stimulation frequencies. The cross-sectional area of muscles was 10.04＋2.52mm2 compared with 7.79＋1.85 mm2 （t =2.84, P =0.047） in control. The frequency of activated satellite cells was 30.63＋6.76% compared with 17.07＋5.36% in control （t =8.73, P =0.000）. Conclusions Direct injection of IGF-I effectively increase extraocular muscle force generation with increased number of activated satellite cells.