小鸡FDM后极部巩膜MMP-2活性表达的动态变化

Dynamic changes of MMP-2 activity in the posterior sclera of chicks with form-deprivation myopia

目的:研究形觉剥夺对小鸡后极部巩膜基质金属蛋白酶2(MMP2)活性的影响以阐明小鸡形觉剥夺性近视眼(FDM)巩膜重塑的可能机制。方法:50只1d龄来亨雏鸡采用半透明塑料眼罩单眼遮盖制备FDM动物模型,按实验时间随机分为FDM4,7,14,21,30d5组,每组10只。对侧非遮盖眼作为自身对照。另外,每组随机选取10只同龄、非遮盖小鸡作为正常对照。于预定实验时间分别采用视网膜镜与A超检测实验眼屈光度与眼轴长度,采用明胶酶谱法检测各组小鸡后极部巩膜明胶酶活性变化。结果:各FDM组后极部巩膜MMP2活性增高,与自身对照、正常对照组比较差异有统计学意义(P<0.01);随着剥夺时间延长,其后极部巩膜MMP2活性水平逐渐升高,至21d达高峰,其后稍下降,但仍维持于较高水平,不同FDM组组间差异有统计学意义(P<0.01);小鸡FDM后极部巩膜MMP2活性动态变化与眼轴长度、屈光度变化呈高度一致;后极部巩膜MMP2活性与眼轴长度呈正相关(r=0.989,P<0.01),与屈光度呈负相关(r=-0.989,P<0.01)。结论:后极部巩膜MMP2活性特异性增高极可能为启动小鸡FDM巩膜细胞外基质(ECM)主动重塑的原因之一。

Objective To investigate the effect of form-deprivation on level of gelatinase in the posterior sclera in chicks. Methods Fifty 1-day-old chicks were monocularly deprived to establish the animal model of form-deprivation myopia (FDM). According to the duration of form-deprivation the experimental chicks were divided randomly and equivalently into 5 groups, which were deprived for 3, 7, 14, 21 and 30 days respectively. Meanwhile the other eyes of the deprived chicks were used as self-control groups and chicks of the same days were chosen randomly as the normal control groups for each FDM group. At each form-deprivation point the changes of degree of diopters and axial length of chicks in each group were recorded. The levels of gelatinase in posterior sclera of the experimental eyes were measured by gelatin enzymography. Results Compared with the normal and self-control groups, the levels of MMP-2 activity in FDM groups were much higher (P<0.01). With the increase of the time of monocular deprivation these changes became more significant and reached the top after 14 days′ deprivation with an inter-group statistical difference (P<0.01). The dynamic changes of MMP-2 activity were the same as those of axial length and degree of diopters in each experimental groups. There was positive correlation between the MMP-2 activity and axial length (r=0.989,P<0.01). But there was a negative correlation between the MMP-2 activity and refractive degree. Conclusion Increase of MMP-2 activity in the posterior sclera of chicks would be a direct key factor to trigger sclera ECM remodeling process in chick FDM.