Effects of enalapril and paricalcitol treatment on diabetic nephropathy and renal expressions of TNF-α, P53, Caspase-3 and Bcl-2 in STZ-induced diabetic rats

This study aimed to assess the renopreventive effect of the angiotensin converting enzyme inhibitor (ACEI), enalapril, and/or vitamin D receptor (VDR) activator, paricalcitol, on streptozotocin (STZ) diabetes-induced nephropathy and to elucidate the mechanisms of action through investigation of the effects on renal oxidative stress, antioxidant defense system and expressions of TNF-, P53, caspase-3, and Bcl-2. Diabetes mellitus was induced in fasting male Wistar rats by single intraperitoneal injection of STZ (45 mg /kg b.w.) dissolved in citrate buffer pH 4.5. Ten days after STZ injection, the diabetic rats were treated with enalapril (25 mg/l of drinking water) and/or paricalcitol (8 {micro}g/kg b.w. per os) dissolved in 5% DMSO daily for 4 weeks. The obtained data revealed that the treatment of diabetic Wistar rats with enalapril and/or paricalcitol led to a significant decrease in the elevated serum urea, uric acid, creatinine and sodium, potassium levels; thereby reflecting improvement of the impaired kidney function. The deteriorated kidney lipid peroxidation, GSH content and GST and catalase activities in diabetic rats were significantly ameliorated as a result of treatment with enalapril and/or paricalcitol. The elevated fasting and post-prandial serum glucose levels and the lowered serum insulin and C-peptide levels were also improved. Moreover, the treatment of diabetic rats successfully prevented the diabetes-induced histopathological deleterious changes of kidney and islets of Langerhans of pancreas. In association, the immunohistochemically detected pro-inflammatory cytokine TNF- and apoptotic mediators P53 and caspase-3 were remarkably decreased in kidney of diabetic rats as a result of treatment, while the expression of anti-apoptotic protein Bcl-2 was increased. Based on these findings, it can be concluded that enalapril and paricalcitol can prevent STZ diabetes-induced nephropathy though amelioration of the glycemic state and antioxidant defense system together with the suppression of oxidative stress, inflammation and apoptosis.