Abstract 400: A Nonpeptide Angiotensin (Ang) II Type 2 Receptor (AT2R) Agonist Improves Diabetic Nephropathy via Inhibition of Renal Inflammation

Abstract

We explored the hypothesis that direct AT2R stimulation improves albuminuria in diabetes by reducing renal inflammation and improving oxidative stress. Sham and DM Sprague-Dawley rats were treated for 4 weeks with vehicle (V) or AT2R agonist Compound 21 (C21; 0.3 mg/kg/d). C21 was infused systemically by osmotic minipump. Diabetes was induced by streptozotocin (65 mg/kg IP). At the end of study, we monitored BP, 24h urine collection for measurements of urinary albumin to creatinine ratio (UACR), and renal interstitial fluid (RIF) levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), nitric oxide (NO), cGMP, and 8-isoprostane (ISO). Data are shown as mean±SE. There were no significant differences in BP between different treatments. UACR (μg/mg), compared to Control+V (14±2), increased significantly in DM+V (60±3, p<0.001) and did not change in Control+C21 (16±2). Compared to DM+V, UACR decreased significantly by 20% in DM+C21 (50±3, P<0.04). RIF TNF-α and IL-6 (pg/min), compared to Control+V (0.040±0.001 and 0.613±0.012, respectively), increased in DM+V (0.046±0.001 and 0.652±0.005, P<0.01) and did not change in Control+C21 (0.041±0.001 and 0.622±0.008). Compared to DM+V, RIF TNF-α and IL-6 decreased in DM+C21 (0.041±0.001 and 0.616±0.007, P<0.01). RIF NO (μmol/min) and cGMP (fmol/min), compared to Control+V (7.0±0.3 and 3.8±0.4), decreased in DM+V (4.3±0.5 and 1.7±0.2, P<0.001) and did not change in Control+C21 (6.6±0.3 and 3.7±0.5). RIF NO and cGMP increased in DM+C21 (6.2±0.8 and 2.7±0.4, P<0.04) compared to DM+V. RIF ISO (pmol/min), compared to Control+V (0.135±0.005), increased in DM+V (0.158±0.007, P<0.02) and did not change in Control+C21 (0.134±0.010). Compared to DM+V, RIF ISO significantly decreased in DM+C21 (0.135±0.006, P<0.03). We concluded that direct AT2R stimulation by the nonpeptide agonist C21 improves diabetic nephropathy through the reduction of renal inflammatory factors and improvement of oxidative stress.