Therapeutic effect of green tea extract on advanced glycation and cross-linking of collagen in the aorta of streptozotocin diabetic rats.

1. The therapeutic effect of green tea extract (GTE) on the aortic collagen content and its characteristics were investigated in streptozotocin diabetic rats. 2. Diabetes was induced in rats by a single intra peritoneal injection of streptozotocin (60 mg/kg bodyweight). Six weeks after diabetes induction, GTE was administered orally for four weeks (300 mg/kg bodyweight daily). Systolic blood pressure, blood glucose, anti-oxidant status, collagen content, extent of glycation, collagen linked fluorescence and aortic collagen solubility pattern were determined in experimental rats. 3. At the end of the experimental period, there was a significant increase in the systolic blood pressure and blood glucose in diabetic rats. The lipid peroxides increased whereas glutathione and vitamin C levels were decreased in the serum of diabetic rats. The collagen content, extent of glycation, the advanced glycation end products (AGEs) and degree of cross-linking were increased in the aorta of diabetic rats. 4. The oral administration of GTE to diabetic rats significantly reduced the systolic blood pressure and blood glucose. The level of lipid peroxides reduced and the content of glutathione and vitamin C increased in the serum of GTE treated diabetic rats. Green tea extract also impede the accumulation of aortic collagen, extent of glycation, formation of AGEs and cross-linking of collagen in diabetic rats. The antihyperglycemic, anti-oxidant and antiglycating effects of GTE ascribed for these beneficial effects. In conclusion, green tea may have therapeutic effect in the treatment of cardiovascular complications characterized by increased AGE accumulation and protein cross-linking associated with diabetes.