| Purpose: Recent studies have documented that the abnormal metabolism of extracelluar matrix(ECM) is involved in the pathological process of diabetic retinopathy(DRP).Matrix metalloproteinases(MMPs) and their tissue inhibitors of metalloproteinase(TIMPs) play a significant role in the metabolism of ECM.The balance between MMPs and TIMPs is important to maitain the normal physiological functions of the retina and is closely related with development of DRP. In order to elucide the action of MMP-2,MMP-9 and TIMP-2 on the development of DRP,the changed expression of MMP-2,MMP-9 and TIMP-2 in the retinae of diabetic mice was qualitative and semi-quantitative analysed in this study. The ultrastructure changes of the retinal microvacular basement membrane were observed at the same time. And this will provide credible theory and aid in the design of new therapeutic approaches to treat and prevent DRP.Methods: C57BL/KsJ db/db monogenetic diabetic mutant mice model imported from Japan were selected as subjects.Twenty-four db/db mice of 6 postnatal weeks were selected while their thin db/+ litters as normal controls.At the end of 2,6,9,12 months,respectively,left eyeballs of the mice for each groups were enucleated.The lateral retinal tissue that is 1mm from the optic papilla,of which the arca is about 1mm2 were removed and fixed in 2.5% glutaraldehyde-phosphoric acid buffer solution(PH7.6)quickly to make samples for transmission electron microscope.The morphological changes of the retinal microvacular basement membrane were observed by the transmission electron microscope. fixed in4% paraformaldehyde,embedded in paraffin to make tissue sections for light study and immnohistochemistry analysis.The computer image-analysing instrument was used to analyse the expression of MMP-2,MMP-9 and TIMP-2 in ganglion cell layer and inner nuclear layer.The analysed indice were mean gray scale value and area density value.At the same time, MMP-2,MMP-9 and TIMP-2 in different cell layerd of retinae were observed and immnolocalized under light microscope.SAS was used to analyse data of this study.Analysis of variance and SNQ-test were used in the statistical. analysis.Results: Compare with that of normal control group, the morphological structure of retinae and the ultrastructure of the retinal microvascular vessels and the basement membrane of it of diabetic mice were not observed abnormal. As diabetes duration progressing, the retinal microvacular basement membrane of C57BL/KsJ db/db diabetic mice were thickened and figure-like projections to lumen discharged fromed cytoplasm of endothelial cells. MMP-2,MMP-9 and TIMP-2 were positively expressed in ganglion cell layer and inner nuclear layer and vascular endothelial cells of retinae of normal control group and diabetes group.As diabetes duration progressing, the mean gray scale value of MMP-2 and MMP-9 increased significantly(p<0.05)and the area density value of MMP-2 and MMP-9 decreased significantly(p<0.05).Arranged as 2,6,9,12 months group, the mean gray scale value of MMP-2 was 105.6±0.9,120.7±2.6*,131.6±3.0*#,143.7±2.0*#△,respectively.The area density value of MMP-2 was 0.09545±0.00714,0.07524±0.00602*,0.05489±0.00613*#,0.03341±0.00353*#△,respectively. Arranged as 2,6,9,12 months group, the mean gray scale value of MMP-9 was 192.7±2.3,174.2±2.5*,160.9±3.2*#,145.8±3.7*#△,respectively. The area density value of MMP-9 was 0.12923±0.00522,0.10696±0.00676*,0.09193±0.00334*#,0.07598±0.00205*#△,respectively. As diabetes duration progressing, the mean gray scale value of TIMP-2 decreased significantly(p<0.05)and the area density value of TIMP-2 increased significantly(p<0.05).Arranged as 2,6,9,12 months group, the mean gray scale value of TIMP-2 was 153.0±5.6 ,145.1±4.3*,136.7±4.1*#,120.5±3.8*#△.The area density value of TIMP-2 was 0.05339±0.00419,0.07354±0.00394*,0.09790±0.00943*#,0.11047±0.01848*#△,respectively. As diabetes duration progressing, the ratio of mean gray scale values of MMP-2/TIMP-2 at the same duration increased significan...
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