Renoprotective effects of green tea extract on renin-angiotensin-aldosterone system in chronic cyclosporine-treated rats.

BACKGROUND Renin-angiotensin-aldosterone system (RAAS) activation plays an important role in cyclosporine (CsA)-induced nephropathy. The main aim of this study was to test whether the administration of green tea extract (GTE) prevents the development of CsA-induced nephrotoxicity. METHODS The rats were treated for 21 days and divided into four groups (n = 6/group): control group (0.9% saline injection), CsA group (30 mg/kg/day by intraperitoneal injection), CsA-GTE group (CsA plus GTE 100 mg/kg/day subcutaneous injection) and GTE group (GTE alone). RESULTS There were significant increased levels of serum blood urea nitrogen and creatinine in the CsA group compared with that of the control group and significantly improved in the CsA-GTE group. Biochemical analysis showed that the plasma renin activity (PRA) and serum concentration of aldosterone were significantly increased in the CsA group compared with the control group and significantly decreased in the CsA-GTE group compared with the CsA group. The total level of renin protein expression was significantly higher in the CsA group than in the control group, and it was lower in the CsA-GTE group than in the CsA group. CONCLUSIONS CsA treatment increases the PRA and intrarenal renin levels and induces nephrotoxicity. The protective effects of GTE on CsA-induced structural and functional alternations of the kidney may be the blockage of RAAS.