Quercetin protected the diabetic glomerulus through decreasing the level of the cyclin-kinase inhibitor p27

Objective To investigate the relationship between the cyclin-kinase inhibitor p27 and the protecting effect of Quercetin on the diabetic glomerulus. Methods STZ-induced diabetic rats were given Quercetin 100 mg·kg -1·d -1 for 8 weeks. The p27 protein of glomerular lysate was detected with Western blotting analysis. The extracellular matrix (ECM) protein (type Ⅳ collagen and fibronectin) of glomerular lysate and 24 h urine albumin were examined with ELISA. Results Glomerular p27 protein and ECM were increased in diabetic rats. Meanwhile, the 24 h urine albumin excretion was elevated proportional to the ratio of kidney weight over body weight in diabetic rats. Quercetin decreased glomerular p27 level (10.6±3.1 vs 18.5±4.3, P0.01), 24 h urine albumin excretion [(17.62±3.02) μg/24 h vs (39.62±3.68) μg/24 h, P0.01], and the ratio of kidney weight over body weight [(11.35±1.76)×10 -3 vs (14.87±2.02)×10 -3, P0.01] of diabetic rats. The blood glucose remained constant in diabetic rats and Quercetin-treated diabetic rats.Conclusion Quercetin protected diabetic glomerulus through decreasing glomerular p27 level.