The Expression Of Laminin Alpha 2 And Matrix Metalloproteinases 2 In Sclera In Defocus-Induced Myopia

Objective:To establish optical defocus-induced myopia(DIM)animal model of guinea pigs and identify the expression of laminin alpha 2(LAMA2) and matrix metalloproteinases 2(MMP-2) from guinea pig DIM the posterior pole of the sclera.Methods:The trichromatic guinea pigs(four weeks old) were randomly assigned to the defocus-induced myopia(DIM)group(n= 10) and normal control group(n= 10).Animals in the DIM group wore- 10.00 D lens in right eye and free in left eye as self-control. Normal control group were without treatment. The refractive errors, axial length, anterior chamber depth, lens thickness and vitreous chamber length were measured respectively before wearing glasses and after wearingglasses1 week, 2 week, 3week.The guinea pigs were killed and both eyes were excised after wearing glasses 3 weeks. The expression level of Laminin alpha 2 protein were determined by western blotting(WB), and the expression level of Lamininalpha2 mRNA and MMP-2 mRNA were determined by reverse transcription-polymerase chain reaction(RT-PCR) from guinea pigs posterior pole of the sclera.Results:Ocular refraction was decreased gradually with the time prolonged in defocus-induced(DI) eye, accompanied by a significant increase in axial length and vitreous chamber depth. The differences of diopter, axial length, vitreous chamber length were changed when DI eye were compared with self-control eye and normal control eye respectively defocus at 1 week, 2 week, 3 week after(P <0.05). The difference of binocular diopter, axial length, vitreous chamber length between the two groups were compared respectively at 1 week, 2 week, 3 week after.The difference were statistically significant(P<0.05).The difference of binocular diopter, axial length, vitreous chamber length at the different time points in defocus group were compared respectively.The difference were statistically significant(P<0.05).The difference of binocular diopter, axial length, vitreous chamber length at the different time points in control group were compared respectively.The difference were no statistical significance(P > 0.05).There were no statistically difference between anterior chamber depth and lens thickness at different time points(P>0.05). The expression of Laminin alpha 2 protein were not detected by WB. The differences of expression level of Laminin alpha 2 mRNA were changed when DI eye(1.1050±0.7824) were compared with self-control eye(1.1350±0.1133) and normal control eye(1.1350±0.1133) respectively. The difference were no statistical significance(P> 0.05).There were no statistically difference of the expression level of Laminin alpha 2 mRNA in normal control group(P>0.05). The differences of expression level ofMMP-2 mRNA were changed when DI eye(0.6792±0.0084) were compared with self-control eye(0.6466±0.0077) and normal control eye(1.1086±0.1067) respectively.The difference were statistically significant(P< 0.05). There were no statistically significant difference of the expression level of MMP-2 mRNA in normal control group(P > 0.05).Conclusions:The myopic shift in refraction and the extension in axial length were evident in the experimental guinea pig eye in response to optical defocus using-10.00 D lens.There is no evidence to prove that whether Laminin alpha 2 involved in sclera ECM remodeling of DIM in guinea pigs. MMP-2 are likely to be the reasons of sclera ECM remodeling of DIM in guinea pigs...