Effect Of1%Sulfate Atropine On Changes Of MMP-2and TIMP-2mRNA Expression In The Posterior Sclera Of Chick With Form-deprivation

Objective We successfully builded the model of chick form deprivation myopia(FDM) to detect the effect of subconjunctival injections of atropine on FDM and to explore impaction and mechanism of atropine on it.Methods402-day-old chick were randomly divided into4different and equal groups, there were normal group, form deprivation group, saline control group and atropine injection group. The right eyes of all chicks were used as experimental eyes.Chicks in the form deprivation group, saline injection group and atropine injection group were monocular deprived by placement of a hood over the right eye. The experimental eyes in saline injection group, and atropine injection group received daily subconjunctival injection of saline solution and atropine(1%), respectively. Optical measurements, axial length and equatorial diameter were accomplished at the end of the14th day. We applied histological analysis to assess sclera changes, which contains two layers:fibrous layer and cartilaginous layers. From the posterior sclera of chicks, we picked up the total RNA. RT-PCR were applied to investigate the expression of matrix metalloproteinase-2(MMP-2) mRNA,and the expression of tissue inhibitor of matrix metalloproteinase-2(TIMP-2) mRNA, respectively.Results Compare with equatorial diameter, axial length and refraction of the eyes in normal control group, those in form deprivation group were remarkably higher (P<0.01). And the scleral cartilaginous layer thickness increased, but the sceral fibrous layer underwent a remarkably thinning (P<0.01). The expression of MMP-2mRNA in the normal control group were remarkably lower than those in form deprivation group(P<0.01), and the expression of TIMP-2mRNA were higher (P<0.01). Atropine can prevent deprivation myopia. Compared with axial length, refraction of form deprivation group, those of atropine group were remarkably lower (P<0.01), but the equatorial diameter of atropine injection group was higher than form deprivation group (P>0.05). And the scleral cartilaginous layer thickness thinning, and fibrous layer of the sclera underwent a remarkably increasing (P<0.01). The mRNA of MMP-2in the form deprivation group were remarkably higher than the expression in atropine injection group (P＜0.01), and the expression of TIMP-2mRNA were lower (P<0.01). The difference between saline control and form deprivation group were not remarkably when optical measures, sclera changes in fibrous layer and cartilaginous layer thickness and the expression of MMP-2and TIMP-2(P>0.05).Conclusion Form-deprivation myopia were able to be caused by monocular covering. Form deprivation myopia were able to be prevented by subconjunctivally ad ministration of atropine. Atropine may prevent form deprivation myopia by regulating the expression of MMP-2mRNA and TIMP-2mRNA in sclera and changing the thickeness of the fibrous layers and cartilaginous layer in the sclera.