| Gastric ulcer is a multi-factor disease of digestive system. Its pathogenesis precise mechanism is unclear. Some researchers considered that an imbalance between defense and invasion effect might result to the disruption of gastric mucosal barrier and the occurrence of gastric ulcer. Bletilla striata (Thunb.) Reichb.f., a traditional Chinese herb, has been widely used for thousands of years. Pharmacological evaluation revealed that Bletilla striata had various biological activities including antimicrobial, antioxidant, anti-inflammatory, immunomodulatory, anti-tumor, Precautionary and therapeutic effect on peptic ulcer. Polysaccharide is an important functional factor in Bletilla striata. Related studies have shown that Bletilla striata polysaccharide has a significant effect on the treatment of gastric ulcer, which was also shown by our previous experiments in our laboratory, however its mechanism is still unknow. In this previous work, Bletilla striata polysaccharide (BSP) was purified, then explored its therapeutic effect on the acetic acid-induced ulcer model. Followings were the main results:1. Extraction, separation and purification of BSPShattering the Bletilla striata’s tuber, BSP was obtained by using water extraction and alcohol sedimentation. After removing the protein and small molecular weight impurity, BSP contents measured by phenol-sulfuric acid method was 45.5%. Protein contents determined by BCA method was 5.5%. By DEAE-Sepharose Fast Flow, BSP was purified and the contents up to 98.2%, protein contents less-than 0.5%.2. Establishment of acetic acid-induced ulcer model on miceThe normal mice as control, we established acetic acid-induced ulcer model. The groups as follow:sham-operated group (saline), model group 1 (10% acetic acid), model group 2 (20% acetic acid), model group 3 (30% acetic acid) and model group 4 (40% acetic acid). The results indicated that:compared with normal mice, saline group had no significant difference (P>0.05), while model group appearred different degrees of gastric ulcer (P<0.01). Model group 1:ulcer index (UI) was relatively small, the survival rate was 100%, but it was easy to heal; Model group 3 and 4:ulcer area was larger than model group 1, self-healing was difficult, but gastric perforation even death was occurred, and the survival rate was greatly reduced; Model group 2:it had appropriate UI, small self-healing capabilities and the survival rate was 100%. Surgery 1-2 days:ulcer had been formed, UI showed growth trend; surgery 3 day:UI was most significant; surgery 4-5 day:UI had no significant change. Considering of experiment effects in the following study, we chose model group 2 (20% acetic acid concentration, surgery 3 day) as the most appropriate model group.3. Therapeutic effect of BSP on acetic acid-induced gastric ulcerSham-operated group as control, the acetic acid-induced ulcer model group 2 was copied and further drugs were administered for 14 day. The groups were following: saline group, omeprazole group (100mg·kg-1.d-1), bismuth potassium citrate group (114mg.kg-1.d-1), BSP low-dose group (10mg.kg-1.d-1), BSP medium-dose group (50mg.kg-1.d-1) and BSP high-dose group (100mg.kg-1.d-1). The results showed that BSP low-, medium- and high- dose group could significantly reduce UI (P<0.01) and increased the ulcer inhibition rate. The ulcer inhibition rates of administration 14 days for all BSP groups were 52.75%,68.02%,70.66%, and the high-dose group was the best group. HE staining found BSP low-, medium-and high-dose group could reduce gastric epithelial defect diameter, neutropenia and other inflammatory cell infiltration, and promote gastric epithelial cell migration, in which the high-dose group had the bestest effect.4. Investigating the therapeutic mechanisms of BSP treating acetic acid-induced gastric ulcermRNA expression of COX-2、VEGF、NF-xBp65、CXCL1 in stomach tissues and the contents changes of IL-1β、TNF-α、IL-10、EGF in serum of mice were determined respectively. The results indicated that the mechanism of BSP on the treatment acetic acid-induced gastric ulcer might be through down-regulating the expression of NF-κBp65 to decrease the COX-2 expression and reduce IL-1β, TNF-α contents, which resulted in the suppression of the inflammatory process. The study also found that BSP could up-regu lation the expression of CXCL1, VEGF and increaselL-10, EGF contents, which could result in cell proliferation, migration, angiogenesis and mucosal tissue reconstruction, thus accelerating the healing of ulcers.In conclusion, BSP has a promising therapeutic effect on acetic acid-induced gastric ulcer, the mechanism may be the suppression of the inflammatory process, promoting the gastric mucosa epithelial cells proliferation, differentiation, migration, angiogenesis and mucosal tissue reconstruction, accelerating the healing of acetic acid-induced gastric ulcer. |
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