Activation of endogenous angiotensin converting enzyme 2 prevents early injuries induced by hyperglycemia in rat retina

Diabetic retinopathy (DR) is a serious complication of diabetes mellitus that may result in blindness. We evaluated the effects of activation of endogenous angiotensin converting enzyme (ACE) 2 on the early stages of DR. Rats were administered an intravenous injection of streptozotocin to induce hyperglycemia. The ACE2 activator 1-[[2-(dimethylamino) ethyl] amino]-4-(hydroxymethyl)-7-[[(4-methylphenyl) sulfonyl] oxy]-9H-xanthone 9 (XNT) was administered by daily gavage. The death of retinal ganglion cells (RGC) was evaluated in histological sections, and retinal ACE2, caspase-3, and vascular endothelial growth factor (VEGF) expressions were analyzed by immunohistochemistry. XNT treatment increased ACE2 expression in retinas of hyperglycemic (HG) rats (control: 13.81±2.71 area%; HG: 14.29±4.30 area%; HG+XNT: 26.87±1.86 area%; P<0.05). Importantly, ACE2 activation significantly increased the RCG number in comparison with HG animals (control: 553.5±14.29; HG: 530.8±10.3 cells; HG+XNT: 575.3±16.5 cells; P<0.05). This effect was accompanied by a reduction in the expression of caspase-3 in RGC of the HG+XNT group when compared with untreated HG rats (control: 18.74±1.59; HG: 38.39±3.39 area%; HG+XNT: 27.83±2.80 area%; P<0.05). Treatment with XNT did not alter the VEGF expression in HG animals (P>0.05). Altogether, these findings indicate that activation of ACE2 reduced the death of retinal ganglion cells by apoptosis in HG rats.

Prevalence of retinopathy in hypertensive patients

To determine the prevalence of retinopathy in hypertensive patients referred to a teaching hospital in Yazd, Iran. This cross-sectional study included 213 hypertensive patients referring to a teaching hospital in Yazd, Iran between November 2004 and June 2005. Data were collected using a questionnaire after an interview and ocular examination. Demographic variables, hypertensive retinopathy, familial history of hypertension, duration of diagnosis, and other hypertension side effects such as cardiac, renal, cerebro-vascular complications were analyzed. The Scheie's staging system was used for retinopathy grading. A total of 213 patients [95 men, 118 women] with high blood pressure aged between 25 and 85 years [mean age of 64.47 +/- 10.66 years] were enrolled in this study, wherein 39.9% of patients suffered from retinopathy. This rate was higher in women [45.6%] than in men [33%]. The positive familial history of hypertension was reported in 47.8% of patients. The prevalence rate of retinopathy in patients suffering from mild hypertension was 25.3%, moderate hypertension was 34.5% and severe hypertension 84.6%. Of the patients with retinopathy, 42.36% had grade I, 20% had grade II and 2.35% had grade III retinopathy. The most common ophthalmoscopic findings were arteriolar narrowing [35.13%], arterio-venous nicking [17.12%] and cotton wool patches [9%]. Positive family history of hypertension and target organs involvement are important risk factors for retinopathy. Early diagnosis and treatment of hypertension to prevent complications is essential