Background: Green tea catechins possess potent antioxidative properties and protect against various oxidative diseases. Malignant stroke-prone spontaneously hypertensive rats (M-SHRSP) develop severe hypertension and spontaneous stroke at early ages. We previously reported that ingestion of green tea catechins prevents cerebral ischemic damage in a middle cerebral artery occlusion and reperfusion rat stroke model, in association with increased plasma epigallocatechin-gallate (EGCG) concentrations. In this study, we examined whether tea catechin intake decreases the incidence of spontaneous stroke in M-SHRSP.
Material/methods: Male M-SHRSP ingested 0.5% green tea catechin extract (Polyphenon E) in their drinking water beginning at 5 weeks of age, and blood pressure, heart rate, and locomotor activity were continuously monitored from 8 weeks using a telemetry system. Stroke onset was assessed by the appearance of neurologic symptoms, body weight loss, and circadian rhythm disturbances in heart rate, blood pressure, and locomotor activity.
Results: Tea catechin ingestion significantly delayed stroke onset by 10 days compared to the control group. Although there was no difference in blood pressure at 10 weeks, the rate of in blood pressure increase in the tea catechin group was significantly smaller than that in the control group. Plasma NO2- and NO3- concentrations increased after stroke in both groups without significant difference between the two groups. Plasma EGCG concentration significantly decreased at post-stroke compared with that of pre-stroke.
Conclusions: Continuous ingestion of green tea catechins from an early age prevented the development of spontaneous stroke in M-SHRSP, probably by inhibiting the further development of high blood pressure at later ages.