Cyclosporine A (CsA) is a potent and effective immunosuppressive agent, but its use is frequently accompanied by severe renal toxicity. CsA-induced nephrotoxicity results from increased production of free radical species in the kidney.The present study was designed to investigate the possible protective effect of green tea extract(GTE) on CsA-induced nephrotoxicity in rats. Eighty male rats were divided into four equal groups. Group 1 rats received no drugs and served as control, group 2 normal rats were treated with green tea extract (3% w/v) orally, group 3 rats treated with CsA (25 mg/kg body weight, orally for 21 days) to induce nephrotoxicity, groups 4 rats received green tea extract for 21 days before, 21 days concurrently during CsA administration and 21 days later after nephrotoxicity induction. Blood samples for serum separation and kidney tissue specimens were collected three times at weekly interval from the last dose of CsA administration. Serum glucose, total Protein, albumin, lipid profile(total cholesterol, triacylglycerols and phospholipids), renal function tests( urea, uric acid and creatinine), electrolytes(sodium and potassium), inorganic phosphorus and haptoglobin levels, lactate dehydrogenase (LDH) and gamma glutamyl transferase(GGT) activities were determined. Moreover, kidney tissue malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO), total antioxidant capacity(TAO) levels, antioxidant enzymes(catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were also determined. The results revealed that, CsA-induced nephrotoxicity caused significant increase in serum glucose, renal functions tests, haptoglobin, lipid profiles and serum marker enzymes (LDH and GGT) with significant decrease in serum total protein, albumin and electrolytes concentrations which were reversed upon treatment with green tea extract. Also, CsA administration induced significant elevation in lipid peroxidation(MDA) along with significant decrease in antioxidant enzyme activities, non enzymatic antioxidant, total antioxidant capacity and nitric oxide level in the rat kidney. Meanwhile, Green tea extract administration improved renal function, by bringing about a significant decrease in peroxidative levels and increase in antioxidant status. These results indicate the renoprotective potential and usefulness of green tea extract, as an excellent source of antioxidants, in modulating CsA-induced nephrotoxicity.
Keywords: Cyclosporine A; antioxidant enzymes, lipid peroxidation; Renal function; Nephrotoxicity; Green tea extract.
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