The Study Of Mechanisms Of Myopia On Preventing Diabetic Retinophty

Diabetic retinopathy(DR) is one of the most common and most serious complications of diabetes,and has become one of the four major causes of blindness. but the pathogenesis of DR is still exploring.Clinical work in ophthalmology,it was noted that the patients with high myopia were often not accompanied by the occurrence of DR,even they had a longer history of diabetes;and the eyes of a higher degree of myopia DR less serious than the contral eye in the diabetic piatient with anisometropia.Study at home and abroad have shown that the severity of myopia and the severity of DR was a negative correlation,but there is no corresponding basis on experiment,therefore,the study of mechanism of high myopia on preventing DR has an important significance on the pathogenesis and treatment of DR.Beacause there is no sympathetic innervation in retina arteriola,so vascular endothelial cell loose vascular smooth muscle by releasing nitricoxide,and loose endothelin-1 to contract blood vessel,the periphery resistance and the leisurely,shorten condition were retained by NO and ET-1,which coordinate the blood circulation,and have more and more effect to occurrence and development of the DR.This study was to establish animal model for high myopia associated with diabetes mellitus in guinea pigs,immunohistochemistry and expression of apoptosis were used to analyze the expression of retinal application of immunohistochemistry in the determination of retinal nitricoxide and endothelin-1,to explore the mechanisms of myopia on preventing diabetic retinophty. Materials and MethodsSity three-old tricolor guinea pigs were selected in this study,weighing 100 130 g,all the guinea pigs to exclude congenital myopia and other eye diseases,and were randomly divided into four groups,The only buffer solution was intraperitoneally injected as normal control in groupⅠ;In groupⅡ,the right eyes of the animals without DM were occluded with self-made transparent eye-goggles to induce the high myopia;DM was induced by repeatly intraperitoneal injection of streptozotocin(STZ) at a low-dose in groupⅢafter regular raise for 6 weeks;and in groupⅣ,the DM was induced at the same way after occluding procedure of the right eyes for 6 weeks.Conjunctival sac of guinea pigs in each group in the right eye were droped by 1%tropicamide carbazole amine compound for 3 times between 10min,the high myopia was determined as the diopter≥-6.00D,and the DM model was identified as the blood glucose≥16.7mmol/L^-1 after 3 days intraperitoneal injection STZ.After 18 weeks,weight,blood glaucose,ocular refraction and axial length measurement were made,and the guinea pigs were sacrificed,retinal tissue was obtained and was given HE,immunohistochemistry stain and expression of apoptosis, respectively to detect the expression of nitricoxide and endothelin-1 in retina. Semiquantitative analysis of the expression of nitricoxide and endothelin-1in retina was measured by the high definition chromatic colour pathoanalytical system. Average optical density value was indicated the degree of the immune reaction.Results1.Comparing body weight and blood glucose Changes in groups:Body weight in the normal control group(Ⅰ) and high myopia group(Ⅱgroup) were significantly higher than diabetic group(Ⅲgroup) and high myopia associated with diabetes mellitus group(Ⅳgroup)(P＜0.05);but there were no significant difference(P＞0.05)betweenⅠandⅡgroup,alsoⅢandⅣgroup.Compared with groupⅠandⅡ,plasma glucose was significantly higher than that in groupⅢandⅣ(P＜0.05),but there were no significant difference(P＞0.05) between groupⅢandⅣ,also groupⅠandⅡ.2.Comparing refraction and axial length change in groups:Refractive in high myopia group(Ⅱ) and high myopia associated with diabetes mellitus group(Ⅳ group) were significantly higher than that in the normal control group(Ⅰgroup) and diabetic group(Ⅲgroup)(P＜0.05);but there were no significant difference (P＞0.05)between groupⅡandⅣ,also groupⅠandⅢ.Axial length in GroupⅡandⅣwere significantly higher than that in groupⅠandⅢ(P＜0.05),but there were no significant difference(P＞0.05)between groupⅡandⅣ,also groupⅠandⅢ.3.Immunohistochemistry staining:ET-1,iNOS protein expression-positive cells mainly distributed in ganglion cells layer,inner nuclear layer,exterior plexiform layer and interior plexiform layer,Immunohistochemistry staining shows that positive expression display as brown.ET-1 protein expression:The expression of ET-1 protein inⅢandⅣgroup were higher that in groupⅠandⅡ(P＜0.05);The expression of ET-I protein inⅢwas higher than that in groupⅣ,but there was no statistically significant(P＞0.05);GroupⅠcompared with groupⅡ,there was no significant difference(P＞0.05).iNOS protein expression:The expression of iNOS protein in groupⅢandⅣhigher than that in groupⅠgroup andⅡgroup(P＜0.05);the expression was higher in groupⅢcompared to groupⅣ,the difference showed a statistically significant(P＜0.05);there was weaklier positive expression of iNOS protein than groupⅠ,the difference showed a statistically significant(P＜0.05).4.TUNEL staining:Apoptotic cells showed as orange in fluorescence microscopy. apoptosis cells scarely be seen in normal retinal photoreceptor,witch increased significantly in diabetic group.Conclusion1.The animal model for high myopia association with DM can be created successfully by a jiont procedure of occlution with self-made transparent eye-goggles and low-dose oft-repeated injection of STZ.2.ET-1/iNOS took part in the mechanisms of myopia on preventing diabetic retinophty by regulating retinal blood flow.3.Apoptosis cells appeared in the early diabetic retina.