Cardiovascular effects induced by Camellia sinensis in experimental diabetes

Diabetes mellitus is a metabolic disorder syndrome characterized by high glucose blood levels because of a reduced insulin secretion by pancreas beta cells and/or reducing biologic activity of this hormone. This syndrome affects carbohydrates, fat and protein metabolism. Diabetic patients exhibit important endothelial alterations associated with the oxidative stress, being one of the most important cause of cardiovascular disorder in these people. Green tea (leaves of Camellia sinensis) is a popular beverage in East Asia, also used as an herbal remedy in Europe and North America. Green tea is being widely studied for its beneficial effect in the treatment and prevention of human diseases. It is considered to be anti-inflammatory, anti-oxidative, anti-mutagenic and anti-carcinogenic and can prevent cardiac disorders. The aim of this study was to evaluate the effects of C. sinensis tea on cardiovascular parameters in diabetic animals induced by a single injection of streptozotocin (STZ, 50mg/kg, i.v.) administered 21 days before the experiments. Induction of diabetes mellitus in animals was confirmed by blood glucose value above 250mg/dl 48h after STZ induction. STZ promoted attenuation in mean BP (˜10% of reduction) as well as in HR (˜20% of reduction) when compared with control animals. Green tea intake prevented the reduction of both parameters, MAP and HR in diabetic animals. These results suggest that although green tea presents important antioxidant action, the presence of caffeine in its extract may have a sympathomimetic action determining changes in blood pressure in animals.

Acknowledgements: MackPesquisa, PIBIC/CNPq