IGF-Ⅰ对外斜视猫模型内直肌Myf5和MyoD表达影响

EFFECT OF INSULIN-LIKE GROWTH FACTOR-I ON THE EXPRESSION OF MYF5 AND MYOD IN THE MEDIAL RECTUS IN A CAT MODEL OF EXOTROPIA

目的观察外源性胰岛素样生长因子-Ⅰ(IGF-Ⅰ)对外斜视猫模型内直肌生肌因子5(Myf5)、成肌分化因子(MyoD)表达的影响,探讨外源性IGF-Ⅰ治疗斜视的可行性。方法选择视觉发育期内的幼猫,行外科手术制备外斜视模型。实验组术后即刻及术后每2周右眼内直肌注射50μL(5μg)IGF-Ⅰ,标准对照组注射50μL生理盐水,空白对照组不做注射治疗。分别于治疗4、8、12周时处死幼猫取眼外肌组织,提取RNA进行荧光定量PCR,观察各组幼猫内直肌MyoD和Myf5表达差异及其与治疗时间的关系。结果治疗4周时,3组Myf5、MyoD mRNA表达量差异无统计学意义(P>0.05);治疗8、12周时,实验组Myf5、MyoD mRNA表达量均较空白对照组、标准对照组升高,差异具有统计学意义(F=14.388~342.990,P<0.01)。实验组Myf5、MyoD mRNA的表达量随治疗时间延长逐渐升高,与治疗时间呈正相关关系(r=0.949、0.949,P<0.01);标准对照组、空白对照组Myf5和MyoD mRNA表达量与治疗时间无相关性(P>0.05)。结论 IGF-Ⅰ局部注射能够促进眼外肌中Myf5和MyoD mRNA的表达,随着作用时间的延长其作用更加明显。

Objective To investigate the effect of exogenous insulin-like growth factor- I （IGF- I ） on the expression of Myf5 and MyoD in the medial rectus in a eat model of exotropia, and to explore the feasibility of exogenous IGF I in the treatment of strabismus. Methods Kittens in visual development stage were selected, and a surgical operation was performed to establish a model of exotropia. The kittens in the experimental group were given the injection of 50 μL （5 μg） IGF- I into the medial rectus of the right eye immediately and every two weeks after surgery, those in the standard control group were given the injection of 50μL normal saline, and those in the blank control group were not given any injection. The kittens were sacrificed at weeks 4,8, and 12 of treatment, the extraocular muscle was collected, and RNA was extracted for quantitative real-time PCR. The groups were observed in terms of the expression of My f5 and MyoD in the medial rectus and its correlation with treatment time. Results At week 4 of treatment, there was no significant difference in the mRNA expression of My f5 and MyoD between the three groups （P〈0.05） ; at weeks 8 and 12 of treatment, the experimental group had significantly higher mRNA expression of My f5 and MyoD than the blank control group and the standard control group （F = 14.388--342.990, P〈0.01）. In the experimental group, the mRNA expression of My f5 and MyoD gradually increased over time and was positively correlated with treatment time （r=0.949 and 0.949 ,P〈0.01） in the standard control group and the blank control group, the mRNA expression of My f5 and MyoD was not correlated with treatment time （P〉0.05）. Conclusion Local injection of IGF- I can promote the expression of My f5 and MyoD in the extraocular muscle in a time-dependent manner.