Effect of saiboku-to, an Oriental herbal medicine, on gastric lesion induced by restraint water-immersion stress or by ethanol treatment

The effect of saiboku-to on gastric lesions induced by restraint water-immersion stress and ethanol has been examined in rats. Thirty minutes after oral administration of saiboku-to, the rats were placed in restraint cages and immersed in water at 23 degrees C for 7 h, or orally administered 99.5% ethanol (1 mt) and placed in normal cages for 1 h. The stress for 7 h or the ethanol treatment for Ih induced erosion in the glandular area of the stomach. Histology showed that the surface epithelial cells were desquamated and part of the lamina propria mucosae was injured. The evaluation of lesion index, the cumulative length of the gastric lesion, on the gross appearance of the stomach, revealed that saiboku-to dose-dependently inhibited both the water-immersion stress-induced gastric erosion and ethanol-induced gastric erosion. To determine whether the anti-erosion effect of saiboku-to was because of a mild irritant effect, saiboku-to or 20% ethanol, which is known as a typical mild irritant, were given orally. After 30 min a strong irritant, 99.5% ethanol, was given orally. Histological examination was performed 30 min after administration of saiboku-to or the mild irritant, and Ih after administration of the strong irritant. The mild irritant induced a reduction in surface epithelial cells 30 min after administration. Furthermore, the mild irritant protected the stomach against mucosal erosion produced by the strong irritant. Saiboku-to protected the strong irritant-induced erosion without producing mild irritation as observed in stomach treated with 20% ethanol. Pretreatment with saiboku-to also inhibited the decrease in the levels of hexosamine, gastric mucus glycoprotein, induced by the strong irritant. In pylorus-ligated rats, saiboku-to dose-dependently inhibited gastric acid secretion, a gastric aggressive factor. These results suggest that the anti-erosion effect of saiboku-to which is not a mild irritant, involves both inhibition of aggressive factors, such as gastric acid secretion, and augmentation of defensive factors, such as gastric mucus cells.