Effects of Catechin on cerebral arteriole vasomotion in spontaneously hypertensive rats

Studies in humans have found consumption of certain flavanoid-containing foods to be associated with improvement in endothelial function and with reduction in blood pressure. In particular, catechin, a natural phenol contained in cocoa and green tea, appears to play a crucial role in the prevention of cardiovascular diseases reducing the systemic arterial blood pressure. The aim of the present study was to in vivo investigate the effects of oral administration of catechin on pial arteriolar rhythmic diameter changes in SHR in comparison with normotensive rats. Catechin was orally administered to SHR for 2 months at the dosage of 30 mg/kg b.w. The pial microcirculation was visualized by fluorescence microscopy. The vessel diameter and rhythmic variations in diameter were evaluated with computer-assisted method. Moreover, the pial arterioles were classified by Strahler scheme in five orders. On 30 min of recordings was performed the Spectral analysis in order to evaluate different frequency components: the first two in the ranges 0.005-0.0095 Hz and 0.0095-0.021 Hz (endothelial activity), the second in the range 0.021-0.052 Hz (neurogenic activity), the third in the range 0.052-0.145 Hz (myogenic activity), finally, the fourth and the fifth in the ranges 0.145-0.6 Hz (respiratory activity) and 0.6-3.0 Hz (heart beat), respectively. The data indicate that SHR treated with catechin presented an increase in the amplitude frequency components related to endothelial activity that in untreated SHR were markedly reduced. In conclusion, the catechin treatment induces the recovery of endothelial activity in SHR where this frequency component was seriously compromised compared to normotensive rats.