A Study Of Intestinal Barrier Changes In A Canine Model Of Ischemic Stroke

Objective: To observe intestinal barrier changes in ischemic stroke and explore it's possible underneath mechanism.Methods: 20 mongrel dogs were randomly divided into 2 groups with 10 in each. Double silicone cylinders measuring 1.1mm in diameter and 8mm in length were placed into their internal carotid arteries in all dogs of group A. And group B served as control, with sham operation. Blood samples were taken at 6 time points, that is before operation(Oh), 0.5h, 3h, 6h, 12h and 24h after operation. The concentration of plasma D-lactate and activity of diamine oxidase(DAO) in plasma were measured at these 6 time points. The concentration of plasma Lipopolysaccharide was measured at the time points of 0h, 12h and 24h. Light microscopic examination was performed for morphological measurement of intestinal epithelial cell. Immunohistochemistry was used to analysis the changes of protein occludin and ZO-1 localizing at tight junction of intestinal epithelial cells. TUNEL staining was performed for apoptosis.Results: Ischemic stroke was confirmed by cranial CT scaning in all dogs of group A. Compared with the test results in group B, the results of DAO at 24h, the results of D-lactate at 12h, 24h and the results of Lipopolysaccharide at 12h, 24h increased significantly in all dogs of group A. The occludin and Zo-1 protein level in group A were significantly lower than that in group B. The apoptotic index in group A was remarkably higher than gourp B. There were positive correlations between the activity of DAO at 24h and the level of D-lac at 24h, 12h, 6h in plasma; between the level of LPS at 24h and D-lac at 24h, 12h, 6h; between the level of LPS at 24h and the activity of DAO at 24h; between the level of LPS at 12h and the activity of D-lac at 24h; between the level of Occludin and ZO-1; between apoptotic index and the level of DAO, D-Lac, LPS at 24h; between apoptotic index and the level of LPS at 12h. There were negative correlations between the level of Occludin, ZO-1 and DAO, D-Lac, LPS at 24h; between the level of Occludin and LPS at 12h; between apoptotic index and the level of Occludin, ZO-1. Observed at the light microscope level, intestinal mucousal injuries were noted in group A, and no obvious changes occurred in group B.Conclusions: (1)The canine model of ischemic stroke in mongrel dogs by placing double silicone cylinders into the internal carotid artery is reliable and suitable for this research. (2)The activity of DAO, concentration of D-lac and Lipopolysaccharide in plasma changed with the destruction of intestinal mucosal function relatively, so detection of them may reflect the destruction of intestinal mucosal function early and sensitively. (3)Destruction of tight junction is one of the molecular mechanisms of pathogenesis of intestinal barrier dysfunction in ischemic stroke.(4)In ischemic stroke, upregulated apoptosis of intestinal epithelial cell was one of the cellular bases of intestine injury. (5)There was intestinal barrier dysfunction in ischemic stroke, eventhough without the effect of nutrition deficiency, infection, hypoperfusion and hypoxia.