Effect of green tea extract on cyclosporine-induced nephrotoxicity in rats

ABSTRACT

Cyclosporine A [CsA] is a potent and effective immunosuppressive agent but its action is frequently accompanied by severe renal toxicity. The present study was designed to investigate the possible protective effect of green tea extract [GTE] on CsA-induced nephrotoxicity in rats. Animals were assigned into three groups as follows I CsA group, given CsA [50 mg/Kg body weight per day, subcutaneously] for 10 days II CsA + GTE group, supplemented with 100 mg/Kg body weight GTE as a daily oral dose three days before and concurrently with CsA treatment and III control group, received the vehicle [olive oil, in the appropriate volume, subcutaneously]. Administration of GTE significantly ameliorated the renal tubular injury caused by CsA as evidenced by decreased urinary enzymes leakage [N-acetvyl-beta-D-glucosaminidase [NAG]. lactate dehydrogenase [LDH] and y-glutamy1 transferase [y-GT] as well as urinary glucose excretion. The deranged renal function was manifested by a significant increase in serum urea and craetinine levels, however, serum sodium and potassium levels were not significantly affected. GET succeeded in improvement of renal dysfunction by normalizing serum urea and creatinie levels. The renal oxidative stress was significantly reduced by GTE administration as evidenced by decreased malondialdehyde [MDA] level as well as enhancement of the antioxidant enzymes glutathione reductase [GR] and gIutathione- S-transferase [GST], however, to significant change in the increased renal gIutathione [GSH] content was observed. The protective effect of GTE was also evidenced by lowering the increased serum and renal nitrte/ nitrate [NOx] levels together with decreasing the elevated renal cytosolic calcium. These findings clearly indicate the protective potential of GTE against CsA-induced nephrotoxicity and suggest a significant contribution of its antioxidant activity to this beneficial effect