Effects of paricalcitol and aliskiren combination therapy on experimental diabetic nephropathy model in rats

Abstract

Background/Aims: The aim of the present study was to investigate the effect of combination of aliskiren with paricalcitol on experimental diabetic nephropathy (DN) model in rats. Methods: Forty male Sprague Dawley rats were divided into 5 groups of 8 rats each, namely the control (Group C), diabetes (Group D), aliskiren (Group A), paricalcitol (Group P), and aliskiren plus paricalcitol (Group A+P) groups. Aliskiren was given by oral-gavage at a dose of 50 mg/kg/day once daily for 12 weeks. Paricalcitol was given by intraperitoneally at a dose of 0,4 mu g/kg/three day of week for 12 weeks. Renal function parameters, oxidative stress biomarkers, mRNA expression of renin-angiotensin system parameters and kidney histology were determined. Results: Group A+P had lower mean albumin-to-creatinine ratio (ACR) (p=0.004) as well as higher creatinine clearance (CCr) (p<0.005) than the diabetic rats (Group D). Combination therapy significantly increased CCr (Group A+P vs Group A, p<0.005; Group A+P vs Group P, p=0.022) and reduced ACR (Group A+P vs Group A, p=0.018; Group A+P vs Group P, p<0.005) when compared to monotherapy. Serum malondialdehyde levels were significantly lower (p=0.004); glutathion levels (p=0.003), glutathion peroxidase (p=0.004) and superoxide dismutase (p<0.005) activities were significantly higher in group A+P than in group D. The mean scores of mRNA expression of renin (p<0.005), angiotensin II (p=0.012) and angiotensin type 1 receptor (p=0.018) in group A+P were significantly lower. Although combination therapy showed no additional effect on oxidative system, renin-angiotensin system and renal histology, aliskiren plus paricalcitol significantly decreased interstitial fibrosis volume when compared to monotherapy (Group A+P vs Group A, p<0.005; Group A+P vs Group P, p=0.002). Conclusion: Our data seem to suggest a potential role of aliskiren plus paricalcitol acting synergystically for reducing the progression of diabetic nephropathy in an experimental rat model.