RENINANGIONTENSINALDOSTERONESYSTEM RAAS BLOCKERS IN DIABETIC NEPHROPATHY DN Nra
RENIN-ANGIONTENSINALDOSTERONE-SYSTEM (RAAS) BLOCKERS IN DIABETIC NEPHROPATHY (DN) Nóra Fanni Bánki SE-MTA “Lendulet” Diabetes Research Group, 1 st Dep. of Pediatrics, Academic Research Group for Pediatrics and Nephrology, Semmelweis University, Budapest 2012 V 4 ACADEMIES FORUM Mátraháza, 26. 10. 2012 fannibanki@yahoo. com
Introduction • By 2035 the number of diabetic patients will reach approximately 400 million (IDF – 2011). • 35 -40% of diabetic patients develop DN within 15 -20 years after the diagnosis (USRDS – 2010). • The 2012 American Diabetes Association protocol recommends the use of ACE inhibitors or ARBs in the case of microalbuminuria (ADA – 2012). • Renal RAAS is activated in diabetes and angiotensin II (Ang. II) level is increased (Ribiero et al – 2008). fannibanki@yahoo. com
Sigma-1 receptor (Sigma-1 R) • The Sigma-1 R is expressed in several tissues and organs (Pontén, 2009). • Renal localization and function are yet unknown. • The activation of Sigma-1 R induces the Akt – endothelial nitric oxide synthase (e. NOS) pathway – protective against hypoxic injury in the heart and brain (Bhuiyan, 2011). – preserves the Na/K ATPase (NKA) in its physiological location (Lei, 2011).
Previous experiments • In Streptozotocin (STZ) induced diabetic rats: – elevated expression and mislocation of renal NKA. – exogenly given Ang. II causes further progression of DN. • Sigma-1 R agonsits are renoprotective against ischemia -reperfusion injury. fannibanki@yahoo. com
Aim To investigate the effect of different RAAS blockers on the pathophysiology of DN and the Sigma-1 R – Akt - NKA system. Angiotensinogen Ang. II ACE enalapril Aldosterone spironolactone eplerenone fannibanki@yahoo. com ANG Receptor losartan
Methods • After 5 weeks of STZ-induced (60 mg/kg iv. ) diabetes, Wistar rats were treated daily p. o. for 2 weeks with a. b. c. d. e. • • • enalapril (40 mg x kg-1 x day-1; n=6), losartan (20 mg x kg-1 x day-1; n=6), spironolactone (50 mg x kg-1 x day-1; n=6), epleronone (50 mg x kg-1 x day-1; n=6), saline (n=6). Blood pressure was monitored non-invasively before and after treatment with a CODA tail-cuff system. Serum and urine parameters were measured and histological scanning of the excised kidney was performed. Protein levels and intrarenal localization of Sigma-1 R-Akt-NKA were evaluated. fannibanki@yahoo. com
Mean arterial blood pressure (MAP) and heart rate Before MAP treatment (mm. Hg) After treatment Before Heart treatment rate After (/min) treatment Control Diabetes (D) D+ Enalapril D+ Losartan 105 + 17 117 ± 20 103 ± 33 110 ± 18 118 ± 22 118 ± 25 100 + 15 103 ± 21 116 ± 29 109 ± 17 108 ± 19 125 ± 11 443 ± 48 366 ± 47* 346 ± 41* 334 ± 39* 349 ± 32* 366 ± 42* 422 ± 70 350 ± 49* 356 ± 26* 362 ± 43 400 ± 20§ 389 ± 35§ * p<0, 05 vs. Control; § p<0, 05 vs. D; n=6 fannibanki@yahoo. com D+ D+ Spironolactone Eplerenone
Laboratory parameters Parameter Control Diabetes (D) D+Enalapril D+Losartan D+Spironolactone D+Eplerenone Body weight(g) 342 ± 2 260 ± 5* 256 ± 7 250 ± 11 349 ± 5§ 273 ± 9 Se glucose (mmol/L) 11. 6 ± 0. 5 43. 6 ± 1. 2* 35. 6 ± 2. 3§ 36. 1 ± 2. 6§ 33. 2 ± 0. 9§ 38. 5 ± 1. 8§ Se cholesterole (mmol/L) 1. 72 ± 0. 19 4. 1 ± 0. 88* 3. 13± 0. 62 2. 72 ± 0. 41 1. 64 ± 0. 12§ 2. 28 ± 0. 2§ LDL-cholesterole (mmol/L) UD 1. 63 ± 0. 74* 0. 65 ± 0. 38 0. 48 ± 0. 24 UD§ Se triglyceride (mmol/L) 1. 32 ± 7 4. 94 ± 1. 4* 4. 54 ± 1. 95 2. 1 ± 0. 68 0. 79 ± 0. 11§ 2. 16 ± 0. 52§ 0. 67 ± 0. 01* 0. 53 ± 0. 02§ 0. 54 ± 0. 01§ 0. 56 ± 0. 01§ 0. 58 ± 0. 01§ Kidney/bodyweight x 100 0. 42 ± 0. 01 Se creatinine (μmol/L) 55. 6 ± 0. 9 64. 6 ± 1. 1* 57. 8 ± 1. 6 54. 8 ± 1. 2§ 56. 7 ± 0. 7§ 69. 3 ± 1. 2 BUN (mmol/L) 7. 12 ± 0. 05 15 ± 0. 5* 11. 9 ± 0. 4 11. 93 ± 0. 2 8. 61 ± 0. 2§ 11. 4 ± 0. 4§ Se Potassium (mmol/L) 5. 78 ± 0. 07 7. 26 ± 0. 14* 7. 24 ± 0. 2 6 ± 0. 08§ 5. 34 ± 0. 2§ 6. 12 ± 0. 01§ Se Sodium (mmol/L) 154 ± 1 135 ± 0. 5* 137 ± 0. 5 138 ± 0. 2 141 ± 0. 3§ 140 ± 0. 3§ * p<0, 05 vs. Control; § p<0, 05 vs. D; n=6; Se – serum, BUN – blood urea nitrogen; LDL – low density lipoprotein fannibanki@yahoo. com
Renal histology Control Diabetes (D) D + Enalapril D + Losartan Mesangial matrix expansion D + Spironolactone Arterial hyalinisation D + Eplerenone * p<0, 05 vs. Control; § p<0, 05 vs. D; n=6; PAS staining; 40 x magnification; scalebar: 50 μm fannibanki@yahoo. com
Renal Sigma-1 R, p. Akt, NKA * p<0, 05 vs. Control; ** p<0, 01 vs. Control; § p<0, 05 vs. D; n=6
Renal Sigma-1 R and NKA localization Green – NKA, Red – S 1 R, Blue – nuclei, 63 x magnification
Summary Paraméter Diabetes (D) vs. Enalapril vs. Losartan vs. Control D D Spironolactone vs. D Eplerenone vs. D MAP - - - Heart rate ↓ - - ↑ ↑ Serum glucose ↑ ↓ ↓ Serum lipids ↑ - - ↓ -/↓ Kidney/body weight ↑ ↓ ↓ Renal function ↓ -/↑ ↑ ↑ -/↑ Renal structure ↓ ↑ ↑ Renal Sigma-1 R - - - Renal p. Akt/Akt ↓ ↑ ↑ Renal NKA ↑ - ↓ ↓ ↓ NKA localization ↓ - ↑ ↑ ↑ fannibanki@yahoo. com
Conclusion • RAAS inhibitor treatment can be used to prevent the progression of DN in these doses without blood pressure lowering side effects in rats. • Aldosterone antagonist monotherapy could beneficial in the prevention of STZ-induced DN. be • The renal Sigma-1 R – Akt – NKA pathway may play a role in the pathophysiology of DN and could serve as a new therapeutic target of RAAS inhibitors. fannibanki@yahoo. com
Plans for the future • Introduction of type 2 diabetic animal models (Zucker rats, db/db mice). • Use of Sigma-1 R agonists (antidepressant fluvoxamine), antagonists and other RAAS inhibitors (ramipril ect. ). • Investigation of depressive behavior with the forced swim test ect. • Evaluation of the NOS system. • In vivo visualisation with multiphoton microscopy. * p<0, 05 vs. Control; § p<0, 05 vs. D; n=6
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