Effect of tea polyphenols on expression of TGF-β_1 in the kidney of streptozocin-induced diabetic nephropathy rats

Objective:To explore the mechanism of action of tea polyphenols(TPs) in the prevention and treatment of early diabetic nephropathy.Methods:Setting up the model of diabetic nephropathy(DN)in rats and then dividing them into five groups:(1)control with resection of one kidney;(2)DN control;(3)DN with treatment of TPs;(4)DN with synchronous treatment of TPs;(5)DN with deferred treatment of TPs.After the model established,their blood sugar and urinary protein in 24 hours were detected at the time point of 0,2 and 4 weeks.Protein and mRNA of TGF -β 1 in their renal tissues were also studied.Results:TPs treatment decreased urinary protein,restrained the up-regulation of TGF-β 1 in renal tissue and protected against early diabetic glomerular injury in DN rats.Preventive treatment of TPs on DN rats shows the best effects.Conclusion:TPs inhibited TGF-β 1 protein and mRNA over-expression in renal cortex of diabetic rats,suggesting that TPs might play a beneficial role in experimental diabetic nephropathy.Its mechanism may be partly by inhibiting TGF-β 1 protein and mRNA over-expression in kidney.