The Role Of The RAS System In Diabetic Retinopathy

Objective Diabetic retinopathy(DR) is one of the most main microvascular lesions in diabetic patients, which can lead to decreased vision and even blindness. Most patients in the early retinal lesions occur no obvious abnormal eye, once appear obvious symptoms, retinopathy is very serious, the loss of the optimal timing of treatment. It is necessary to further study the pathogenesis of DR. This experiment was to study renin angiotensin system(RAS) in the process of different stages of diabetic retinopathy 、cells apoptosis of retinal nerve And the expression of ERK pathway to understand the renin angiotensin system role in diabetic retinopathy.Methods First,we selected 62 healthy adult male SD rats, the rats were randomly divided into control group and diabetes group. The control group were 22, diabetes group were 40. STZ diluted to 1%,using citrate buffer. Intraperitoneal injection of 50 mg/kg STZ to destruction of SD rat islet beta cells, determination of caudal vein blood sugar after 48 h,the blood sugar higher than 16.9 mmol/L we belived the rats having the diabetes,9 rats had dead.After a week,determination of caudal vein blood sugar,,the blood sugar higher than 16.9 mmol/L we build the diabetic rat model success,5 rats had dead. The control group by intraperitoneal injection of pure citrate buffer. Diabetic rats significantly more drinks, food, thin symptoms. In the control group and 4 weeks, 8 weeks and 12 weeks in diabetes group of seven SD rats were randomly selected.Take 4 eyes to paraffin embedding,10 eye separation retinal tissue under the microscope, EP in tube cryopreserved- 80 ° C. Second, the expression of CD14 and 8- hydroxyl deoxyguanosine(8 – OHd G) were detected by Immunohistochemical in 4 weeks, 8 weeks and 12 weeks of diabetes and normal control group. Third, the m RNA expression of AT2 R and PRR in 4 weeks, 8 weeks and 12 weeks of diabetes and normal control group are detected, respectively. Last, the levels of extracellular signal-regulated kinase(ERK) 1/2,p ERK1/2 proteins are measured by Western blot.Results AT2 R m RNA expression level in Diabetes groups and control group were:(1.890±1.015),(2.127±0.838),(2.293±1.039),(2.243±1.258)and PRR m RNA expression level in Diabetes groups and control group were:(1.653±1.019),(2.260±0.916),(2.640±1.028),(2.880±1.090). AT2 R and PRR m RNA expression level in Diabetes groups are higher than the control group significantly, and the expression level is increasing with the extension of the course. The control group, 4 weeks, 8 weeks and 12 weeks course of rat 8- OHd G immunohistochemical optical density were :(0.1827±0.025)、(0.1987±0.021)、(0.2425±0.314)、(0.252±0.028).The longer the course of the disease, the more rats retinal cells apoptosis in diabetes group. There are less new blood vessels in diabetes group as the CD14 dyeing are negtive. Through correlation analysis, PRR and AT2 R expression level are associated with the ganglion cell apoptosis. In diabetes groups ERK1/2, p ERK1/2 protein expression are significantly higher than the control group.Conclusion AT2 R and PRR m RNA expression level are related with the cell apoptosis of rats with diabetic retinopathy. After the onset of diabetic retinal tissue of rats in the renin angiotensin system is apparent activation. And with the development of the course of the RAS system function gradually strengthened. RAS may play a key role of diabetic retinopathy though increasing the phosphorylation of ERK level.