Effect of dual blockade of renin-angiotensin system on renal nephrin and vascular endothelial growth factor – A expression in diabetic-hypertensive rats

Abstract

The effects of early renin-angiotensin system (RAS) blockade using angiotensin-converting enzyme (ACE) inhibitor lisinopril and/or angiotensin receptor blocker valsartan on renal nephrin and vascular endothelial growth factor (VEGF)-A gene expression were investigated in diabetic-hypertensive rats. Diabetes and hypertension were induced in adult Wistar rats using streptozotocin (45 mg/kg, i.p.) and Nω-nitro-L-arginine methyl ester (60 mg/kg/12 h) for 4 consecutive days. Experimental animals were allocated into six groups (n = 6): normal control, diabetic control, diabetic-hypertensive control and lisinopril-, valsartan- and combination-treated diabetic-hypertensive groups (5 mg/kg/drug/day, p.o., for 21 days). Blood glucose, blood pressure, body weight, kidney weight to body weight ratio, serum albumin, creatinine, total protein and urea were measured and recorded every week. Nephrin and VEGF-A gene expression were measured using real-time polymerase chain reaction. Renal nephrin protein was measured using ELISA as well as nephrin immunostaining. Blood pressure was significantly decreased by all treatments (P ≤ 0.05). All treatments normalised serum albumin and urea. Serum creatinine significantly decreased, while total protein significantly increased (P ≤ 0.05). Nephrin gene expression had a non-significant decrease in diabetic-hypertensive rats, yet it was statistically increased with individual treatments (P ≤ 0.05) and normalised with combined treatment. Renal nephrin protein significantly decreased in diabetic-hypertensive rats, normalised by lisinopril and significantly increased by valsartan and combined treatments (P ≤ 0.05). VEGF-A expression significantly increased in diabetic-hypertensive rats and significantly decreased with lisinopril and valsartan monotherapy and normalised with combined treatment (P ≤ 0.05). Immunostaining of nephrin also showed an obvious increase in the case of combined treatment. Early dual blockade of RAS in diabetic-hypertensive rats protected against renal damage and improved renal nephrin and VEGF-A gene expression as well as renal nephrin protein expression.