Effect of green tea on kidney tubules of diabetic rats

Abstract

It has been documented that green tea (GT) and its catechin components improve renal failure and inhibit the growth of mesangial cells. In the present study we examined the long-term effect of GT extract on streptozotocin (STZ)-induced diabetic nephropathy and on the glycogen accumulation in the kidney tubules. Male Sprague -Dawley rats were randomly assigned to normal control groups (2, 6, 8 and 12 weeks) and five diabetic groups (n 10) of comparable age. A GT diabetic group received 16 % concentration of GT for 12 weeks post-diabetes induction as their sole source of drinking water. GT treatment significantly (P,0·01) reduced the serum glucose, glycosylated protein, serum creatinine and blood urea N levels by 29·6 (SEM 3·7), 22·7 (SEM 5·2), 38·9 (SEM 10) and 41·7 (SEM 1·9) %, respectively, compared with the diabetic group of comparable age. In addition, the GT-treated group showed a significant 44 (SEM 10·8) % higher creatinine clearance (Ccr) compared with the untreated diabetic group. Likewise, GT reduced the urea N, creatinine, glucose and protein excretion rates by 30 (SEM 7·6), 35·4 (SEM 5·3), 34·0 (SEM 5·3) and 46·0 (SEM 13·0) % compared with the 12 weeks diabetic group. Administration of GT to 12 weeks diabetic rats significantly (P, 0·001) prevented (99·98 (SEM 0·27) % less) the accumulation of glycogen in the kidney tubules. These results indicate that in STZ diabetes, kidney function appears to be improved with GT consumption which also prevents glycogen accumulation in the renal tubules, probably by lowering blood levels of glucose. Therefore, GT could be beneficial additional therapy in the management of diabetic nephropathy. Green tea: Polyphenols: Diabetic nephropathy: Proximal tubulesDiabetes mellitus is characterised by hyperglycaemia, which has been strongly linked to diabetic complications such as neuropathy, retinopathy and nephropathy. Above all, diabetics are at augmented risk for end-stage renal disease consequent to diabetic nephropathy (1,2) . Stringent control of the hyperglycaemia by insulin treatment has been shown to avert hypertrophy and hyperfiltration and the subsequent rise in urinary protein excretion (3) . Clinical studies suggest that there is yet no completely effective treatment for diabetic nephropathy (4) . Hyperglycaemia is the principal factor responsible for structural alterations at the renal level and is directly linked to diabetic microvascular complications, particularly in the kidney (4) ; therefore, glycaemic control remains the main target of treatment. Prevention of nephropathy is a very important concern and many studies have been focused on traditional and herbal medicines to find novel therapeutic agents for diabetic nephropathy.Green tea (Camellia sinensis; GT) is a rich source of polyphenols, particularly flavonoids, which have been shown to have numerous pharmacological effects. Studies using animal models show that GT catechins could be beneficial in suppressing high-fat diet-induced obesity by modulating lipid metabolism and providing some protection ag...

Altered Kidney Morphology and Enzymes in Streptozotocin Induced Diabetic Rats

“…These findings of present study are in agreement with the findings of Ramesh et al, Kim et al (2008) and Renno et al (2008) who showed tubular epithelial changes, enlargement of lining cells of tubules and accumulation of glycogen in the kidney tubules. Glycogen accumulation in the renal tubules could be attributed to hyperglycaemia induced by streptozotocin-induced diabetes.…”

Nephroprotective effects of ethanolic extract of Sesamum indicum seeds (Linn.) in streptozotocin induced diabetic male albino rats

“…The diabetic rats had increased levels of creatinine and urea which are considered as significant markers of renal function and this is in agreement with the present result. [37] Renno et al [38] demonstrated that green tea extract provides a beneficial effect on long-term diabetic nephropathy via suppressing hyperglycemia and preventing glycogen accumulation in the proximal tubules. The diabetic hyperglycemia induces elevation of the plasma levels of urea, uric acid and creatinine which are significant markers of renal dysfunction and reflecting a decline in the glomerular filtration rate.…”

Edible plants from traditional Chinese medicine is a promising alternative for the management of diabetic nephropathy

“…Recent research using STZinduced rat as diabetic model revealed that the renal function, blood glucose and glycated protein profiles were improved in rats supplemented with green tea in the drinking water. Moreover, the renal mitochondrial reactive oxidative species (ROS) production of STZ-induced diabetic rat was also reduced by green tea (Renno, Abdeen, Alkhalaf, & Asfar, 2008). With regard to tannins, its scope of distribution in natural plant is diversified.…”

“…Some kinds of (Renno et al, 2008) (continued on next page) mushrooms are used as functional foods as well as prescription ingredients in traditional medical system. Their hyperglycemic effects have been proven both experimentally and clinically (Perera & Li, 2011).…”