Inhibitions of platelet-activating factor production and granulocyte oxidative activation by Rikkunshi-To in the process of gastric mucosal injury

The effects of Rikkunshi-To on gastric mucosal injury were investigated with attention to the mechanisms of oxidative stress. Repeated electrical stimulation (RES) on the gastric artery of male Wistar rats decreased mucosal blood flow, which was measured by laser Doppler flowmetry, and subsequently produced hemorrhagic lesions in the gastric mucosa. At 30 min after the completion of RES, increased platelet-activating factor (PAF) content and myeloperoxidase (MPO) activity were observed in the gastric mucosa. Luminol-dependent chemiluminescence activity in blood samples taken from a gastric vein was also elevated after the stimulation. Oral administration of Rikkunshi-To (50 mg/kg) attenuated the increases in luminol-dependent chemiluminescence activity, mucosal PAF content and MPO activity, and the decrease in mucosal blood flow, and prevented mucosal injury induced by the electrical stimulation. These results support the concept that PAF is involved in granulocyte-mediated oxidative stress and gastric mucosal injury, and suggest that Rikkunshi-To prevents mucosal microvascular injury and formation of hemorrhagic lesion by modulating PAF production and oxidative granulocyte activation.