Polyphenols in Theobroma Cacao Ameliorate Microcirculation: In vivo Intravital Microscopic Observation in Rats

It has been reported that ingestion of cocoa or chocolate reduces blood pressure in the subjects with hypertension. To clarify the hypotensive activity of cocoa, we carried out the research on microcirculation using intravital microscopic technique. First, we estimated the influence of repeated treatment of cocoa on microcirculation. Male rats fed normal diet (ND) or 15% fat containing high fat diet (HFD) or 0.2% flavan-3-ols containing HFD for 6weeks. Under anesthesia, the arteriole function of mesentery in rat was observed under physiological condition. Vasocontraction induced by the phenylephlin was significantly reduced in the HFD group compared with that in ND group, there was not such change in the HFD with cocoa group. Endothelium dependent vasodilatation stimulated by acetylcholine was significantly decreased in the HFD group compared with that in ND group. On the other hand, endothelial dysfunction of arteriole induced by HFD was not shown in cocoa group. In addition, single oral administration of cocoa or its flavan 3-ols on microcirculation in skeletal muscle was estimated. Cocoa (100 mg/kg) or flavan-3-ols derived from cocoa (10 mg/kg) was administrated through a feeding tube to the animals, velocity of red blood cells in precapillary arteriole and the number of newly recruited capillary in cremaster muscle were significantly increased by the treatment of cocoa or flavon-3-ols compared with vehicle, accompany with elevation of heart rate and blood pressure. These research has revealed that the ingestion of cocoa improves endothelial dysfunction of arterioles which is major determining of blood pressure induced by the high fat diet and single oral administration of flavan 3-ols in cocoa altered microcirculation in skeletal muscle and general circulation. These acute effects might be related with the preventive action of flavan-3-ols on cardiovascular disease.