胰岛素样生长因子Ⅰ对实验性外斜视猫内直肌肌分化因子5、转化生长因子β1表达的影响

The influence of IGF-Ⅰ on the expression of Myf5 and TGF-β1 in medial rectus muscle of cat model with strabismus

目的探讨外源性胰岛素样生长因子Ⅰ（IGF-Ⅰ）对外斜视猫模型内直肌肌分化因子5（Myf5）、转化生长因子β1（TGF-β1）表达变化的影响。方法实验研究。选择处于视觉发育敏感期内幼猫（4-6周）27只，采用随机数字表法分为实验组、无菌水对照组和空白对照组，各组再根据药物干预时间分为4周亚组、8周亚组、12周亚组，每亚组3只。通过缩短外直肌并前徙制作右眼外斜视幼猫模型后，实验组将外源性IGF-Ⅰ 0.05 ml（0.1 g/L）注射到右眼内直肌建立外斜视治疗模型；无菌水对照组注射等量无菌水；空白对照组未进行注射。各组分别于药物干预后4、8、12周取完整右眼内直肌，采用免疫组织化学染色法检测内直肌Myf5和TGF-β1平均吸光度（A）值。采用Kruskal-Wallis、Bonferroni检验方法分析Myf5和TGF-β1表达的变化，采用简单线性回归等方法分析Myf5和TGF-β1表达与药物干预时间的相关性。结果（1）药物干预4周时，实验组内直肌Myf5的A值（33.34±17.16）与无菌水对照组（21.30±7.44）和空白对照组（18.95±6.59）比较，差异无统计学意义（χ2=4.646，P〉0.05）；药物干预8、12周时，实验组内直肌Myf5的A值分别为39.24±15.25和47.70±19.39，高于同时间点的无菌水对照组（19.43±4.75、4.82±2.66）和空白对照组（18.00±7.29、5.86±2.61），差异均有统计学意义（χ2=21.864、31.814，均P〈0.01）。实验组内直肌Myf5的A值随着IGF-Ⅰ干预时间的延长呈增加趋势（R2=0.99，P〈0.05）；无菌水对照组及空白对照组内直肌Myf5的A值随时间延长呈降低趋势（R2=0.81、0.80，均P〈0.05）。（2）药物干预4、8、12周时，实验组内直肌TGF-β1的A值分别为0.80±0.12、0.53±0.09和0.42±0.08，均低于同时间点的无菌水对照组（1.91±0.23、2.30±1.03、1.82±0.72）及空白对照组（2.01±0.31、2.62±1.11、1.83±0.67），差异均有统计学意义（χ2=30.801、40.278、35.177，均P〈0.01）。实验组内直肌TGF-β1的A值随着IGF-Ⅰ干预时间延长呈降低趋势（R2=0.83，P〈0.05）；无菌水对照组及空白对照组内直肌TGF-β1A值与时间无相关性趋势（R2=0.04、0.06）。结论外源性IGF-Ⅰ对外斜视猫模型内直肌中Myf5的表达具有增强作用，对TGF-β1的表达具有抑制作用。重复注射外源性IGF-Ⅰ可使Myf5持续增强表达，TGF-β1持续减弱表达。

ObjectiveTo observe the influence of exogenous insulin-like growth factor-Ⅰ（IGF-Ⅰ） on the expression of myocyte differentiation factor 5 （Myf5） and transforming growth factor β1（TGF-β1） in medial rectus muscle of cat model with strabismus. Methods Experiment research. Twenty-seven kittens which were in sensitive period of visual development （4-6 weeks old）, were randomly divided into experimental, control and blank control groups by random numbers table method. Each experimental group was further divided into 3 sub-groups （4 weeks, 8 weeks and 12 weeks） based on drug intervention time, hence 3 kittens in each sub-group. The control group and the blank control group were also divided into 3 sub-groups respectively. Exotropia treatment models were set up through surgical methods and injection of IGF-Ⅰ（0.05 ml,0.1 g/L）. The internal rectus muscles of 4 weeks sub-group, 8 weeks sub-group and 12 weeks sub-group were taken respectively after the treatment model had been set up. The internal rectus muscles of the control group and the blank control group were also taken according to corresponding time. The expressions of Myf5 and TGF-β1 were tested with immunohistochemistry staining method, and optical density analysis method were employed to measure the average optical density value. The expression of Myf5 and TGF-β1 was analyzed by Kruskal-Wallis and Bonferroni test. The correlation between the expression of Myf5 and TGF-β1 and the time of drug intervention was analyzed by simple linear regression.Results（1） In the experimental group, the expression of the Myf5 of the 4 weeks sub-group, 8 weeks sub-group and 12 weeks sub-group were 33.34±17.16, 39.24±15.25 and 47.70±19.39, which were higher than the control group （21.30±7.44, 19.43±4.75, 4.82±2.66） and the blank control group （18.95±6.59, 18.00±7.29, 5.86±2.61） at the same time point, and the differences were statistically significant in 8 weeks sub-group and 12 weeks sub-group （χ2=21.864, 31.814, both P〈0.01）. The expression of Myf5 in the experimental group increased with the extension of IGF-Ⅰ intervention time （R2=0.99, P〈0.05）. But there were negative correlation between expression of Myf5 and drug intervention times in the control group and the blank control group （R2=0.81, 0.80, both P〈0.05）. （2） In the experimental group, the expression of the TGF-β1 of the 4 weeks sub-group, 8 weeks sub-group and 12 sub-weeks group were 0.80±0.12, 0.53±0.09, 0.42±0.08, which were higher than the control group （1.91±0.23, 2.30±1.03, 1.82±0.72） and the blank control group （2.01±0.31, 2.62±1.11, 1.83±0.67） at the same time point, and the differences were statistically significant （χ2=30.801, 40.278, 35.177, all P〈0.01）. The expression of TGF-β1 in the experimental group decreased with the extension of IGF-Ⅰintervention time （R2=0.83, P〈0.05）. The average optical density value regression equation of TGF-β1 in the sterile water control group and the blank control group was 0.04 and 0.06, respectively, and the fitting degree was very poor. Therefore, there was no correlation trend with time.ConclusionsExogenic IGF-Ⅰ could enhance the expression of Myf5 in medial rectus muscle of cat model with strabismus. Exogenic IGF-Ⅰ could inhibit the expression of TGF-β1 in medial rectus muscle of cat model with strabismus. Repeated injection of exogenous IGF-Ⅰ may continuously enhance the expression of Myf5 and inhibit the expression of TGF-β1.