Angiotensin Ⅱ, Vascular Endothelial Growth Factor And Diabetic Retinopathy

Purpose: In order to elucide the action of Ang II and VEGF on the development of diabetic retinopathy ,the changed expression of angiotensin II (Ang II) and vascular endothelial growth factor (VEGF) in the retinas of diabetic mice was qualitative and semi-quantitative analysed in this study.Methods: This study is composed of three parts. (1) The first part: C57BL/KsJ db/db monogenic genetic diabtic 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 after being perfused with 4% paraformaldehyde, fixed in 10% neutral bufferd formalin, embedded in paraffin to make tissue sections for light study and immunohistochemistry analysis. The computer image-analysing instrument was used to analyse the expression of Ang II and VEGF in ganglion cell layer. The analyased indexs were mean gray scale value and area density value .At the same time , Ang II and VEGF in various cell layers of retina were observed andimmunolocalized under light microscope. Analysis of variance and correlation analysis were used in statistical management.(2) The second part: Male C57BL/KsJ db/+ mice were obtained at 3 weeks of age and fed on diets enriched animal fat (36% w/w) for 4 weeks. After exposure to high-fat diet for 4 weeks, mice were fasted 12 hours and then injected intraperitoneally with streptozotocin (STZ) lOOmg/Kg body weight and kept on the same diet for the next 3 weeks. Under nonfasting conditions, plasma glucose concentration was measured at the end of 4 (before STZ injection), 5, 6, 7 weeks, respectively. At the end of 5 weeks nonfasting insulin concentration was measured. Mice fat-fed injected STZ were kept. At the end of 11 weeks(after STZ injection 7 weeks) and 14 weeks (after STZ injection 10 weeks) respectively, mice were perfused with Karnovsky' solution to make samples for transmission electron microscope. The morphological changes of retina were observed by transmission electron microscope. Comparisons were done with t test and analysis of variance.(3) The third part: Male C57BL/KsJ db/+ mice were obtained at 3 weeks of age and fed on diets enriched animal fat (36% w/w) for 4 weeks. After exposure to high-fat diet for 4 weeks, mice were fasted 12 hours and then injected intraperitoneally with streptozotocin (STZ) lOOmg/Kg body weight. After 2 weeks nonfasting plasma glucoseconcentration was measured by nipping the distal part of the tail. Mice whose plasma glucose concentrations were higher than ll.lmmol/L were selected as those of model groups. From the second day after the model was set up , captopril 12.5mg/Kg body weight or valsartan 40mg/Kg body weight was given to treatment group via the oral route and the same volume salt solution was given to control group. After treatment 4 ,8 ,12 weeks .respectively, eyeballs of the mice for each groups were enucleated after being perfused with 4% paraformaldehyde, fixed in 10% neutral bufferd formalin, embedded in paraffin to make tissue sections for light study and immunohistochemistry analysis. The computer image-analysing instrument was used to analyse the expression of Ang II and VEGF in ganglion cell layer. The analyased indexs were mean gray scale value and area density value . At the same time , Ang II and VEGF in various cell layers of retina were observed and immunolocalized under light microscope. Analysis of variance , t test and correlation analysis were used in statistical management.Results:(1) The first part :Compare with that of normal control group,the morphological structures of retinas of diabetic mice were not observed abnormal. Ang II and VEGF were not expressed in various layers of retinas of normal control group. Ang II immunohistochemistry of retinas showedpositive expression in the ganglion cell layer ,and some cells in the in...