Abstract:
Centella asiatica (L.) Urban, locally known as Bua Bok, has been used for treatment of wound healing and digestive disorders (e.g. dysentery, diarrhea). The healing effect and anti-inflammatory effect of C. asiatica (L.) Urban lead to studies of antiulcer activity. The action of C. asiatica (L.) Urban in peptic ulcer treatment may be through the modification of gastric function. Thus, this study is attempted to investigate the effects of fresh expressed juice of C. asiatica (L.) Urban on the gastric function and to clarify the usefulness of C. asiatica (L.) Urban in gastric mucosal protection. The effects of fresh expressed juice of C. asiatica (L.) Urban on gastric secretion were evaluated in secretagogue-induced (histamine and carbachol) gastric fistula rats by comparison to ranitidine (H2-antagonist). After the first hour of gastric sample collection the rats were divided into two groups. Histamine was injected into one group and carbachol into the other; histamine (10 mg/kg, IM) or carbachol (20 μg/kg, IV) was injected to stimulate gastric secretion. Water or the C. asiatica (L.) Urban extracts (1, 2, 4 and 8 g/kg) or ranitidine (25 mg/kg, IM) was intraduodenally injected. The sample collection was taken at 1-hour intervals for 4 more hours. The collected samples were determined for the content of H+, pepsin, protein and soluble mucus. At the end of the 5 hours period, the glandular part of the stomach was removed and assayed for the visible mucus content. In addition, the effect of C. asiatica (L.) Urban on gastric mucosal blood flow was evaluated in histamine-induced gastric mucosal blood flow by using Laser Doppler Flowmetry. Ranitidine inhibited histamine- and carbachol-induced gastric acid and pepsin secretion. Ranitidine had a maximum inhibition on acid and pepsin stimulating effects of histamine greater than that of carbachol. Ranitidine inhibited gastric soluble mucus secretion only in histamineinduced rats. Ranitidine had no effect on gastric visible mucus of both secretagogue-induced gastric secretion. C. asiatica (L.) Urban extracts (1, 2, 4 and 8 g/kg) had no effect on acid, pepsin and visible mucus secretion induced by histamine or carbachol. In the histamine treated group, all the doses of C. asiatica (L.) Urban had no effect on soluble mucus secretion, while C. asiatica (L.) Urban extract at the dose of 4 and 8 g/kg had a tendency to increase gastric soluble mucus secretion in carbachol treated rats. C. asiatica (L.) Urban at the dose of 4 g/kg showed significantly increased gastric mucosal blood flow similar to that of histamine-treated rats. C. asiatica (L.) Urban at the dose of 8 g/kg inhibited histamine increasing gastric mucosal blood flow. However, this inhibition was lower than ranitidine. This study indicates that C. asiatica (L.) Urban leaves does not have any effect on gastric secretion. C. asiatica (L.) Urban inhibits histamine increasing gastric mucosal blood flow at high doses showing a potentially anti-inflammatory activity which supports its antiulcer effect.