The Expression Of Matrix Metalloproteinase-2 And Its Tissue Inhibitor In The Posterior Sclera Of Guinea Pig With Form-deprivation Myopia

Objective To investigate the expression of matrix metalloproteinase 2(MMP-2) and its tissue inhibitor(TIMP-2) mRNA in posterior sclera of guinea pig eyes with form-deprivation myopia(FDM).Methods 25 4-week-old guinea pigs were divided randomly and equivalently into five groups,and the right eye of each guinea pig with monocular deprivation(MD) for 1,4,7,14 and 21 days respectively to induce FDM, the left eye served as self-control. Meanwhile, normal age-matched animals were provided as negative control speciments for each group.Removing the goggle at every experimental point refractive status and axial length were determined with streak retinoscopy (without cycloplegia) and A-scan ultrasonography under topical anaesthesia respectively.Both eyes collected after guinea pigs were killed,and total RNA in the posterior sclera was extracted traditionally using TRIZOL reageant and expression levels of MMP-2 and TIMP-2 mRNA were analyzed by two-step reverse transcription-polymerase chain reaction.Results The levels of MMP-2 mRNA expression in posterior sclera of guinea pig with MD began to increase on the first day of form-deprivation, and reached a peak on the 7th day of form-deprivation,after which it decreased slightly and maintained in a relative high level.It existed statistical different between MD groups(P < 0.01).Compared with normal and self-controlled groups,the levels of MMP-2 mRNA expression in the posterior sclera of guinea pig with MD were higher,except for MD1d.It was statistical different between MD and control groups(P< 0.05).The changes of MMP-2 mRNA expression in self-controlled groups was similar to each MD groups,but the levels were all less than that of MD groups.It existed statistical different between self-controlled groups(P < 0.01).Meanwhile,With extension of form-deprivation duration levels of TIMP-2 mRNA expression in posterior sclera of guinea pig with MD expression decreased. It existed statistical different between MD groups(P<0.01).The change of self-controlled groups levels of TIMP-2 mRNA expression in the posterior sclera is similar to each MD groups.It existed statistical different between self-controlled groups(P<0.01). Conclusion Imbalance between expression of MMP-2 and TIMP-2 mRNA would probably be an important factor to trigger early scleral extracellular matrix (ECM) remodeling process to develop FDM by degradating scleral ECM excessively.