Experimental Study Of The Relationship Between The Angiopoietin-1/ Tyrosine Kinase Receptors-2 System And The Neoangiogenesis In Lower Esophagus Of Rats With Portal Hypertension

ObjectTo establish a rat model of portal hypertension and explore the relationship between the angiopoietin-1/tyrosine kinase receptors-2 system and the neoangiogenesis in lower esophagus of rats with portal hypertension. MethodFifty SD rats, with the same sex and similar weight, were randomly divided into two groups: experimental group(thirty rats, partial portal vein and left suprarenal vein were ligatured to make portal hypertension model) and control group(twenty rats, the portal vein and left suprarenal vein were separated but not ligatured). The lower esophageal tissue was obtained two weeks after the operation. The immunohistochemical streptavidin-perosidase(SP) technique was used to detect the expressions of Ang-1 and Tie-2. The esophageal wall tissue￠s microvessel density(MVD) was assessed by immunohistochemical studies of CD34. Then the differences between the expressions of Ang-1 and Tie-2 in this two groups were analyzed, and the relevance between the the expression of Ang-1 or Tie-2 and MVD was studied. ResultThe models of portal hypertension were set up successfully in 37 rats(17 in experimental group and 20 in control group). The pathologic changes in the enterocoelia of experimental group was found: conglutination, large numbers of faint yellow ascites(probably 5-10ml), the liver with darken colours, the passive congestion edema of the stomach and the intestine and the spleen, the spleen with darken colours and a larger size, the remarkable varicose veins on the surface of esophagus and stomach and omentum. The pathologic changes in the enterocoelia of control group was found: nothing besides the conglutination. The pathologic performance of the histologic section in the experimental groups after the hematoxylin-eosin staining: the passive congestion edema existed in mucous layer of esophagus in experimental group, and the mucous layer had incrassation and varicosity and the cirsoid veins were filled with a mass of red cells, and inflammatory cells infiltrated in mucous layer and submucosa. The pathologic performance of the histologic section in the control groups after the hematoxylin-eosin staining: nothing abnormal happened. Two weeks after the operation, we took the lower esophagus of rats in both of the two groups. The expressions of Ang-1(128.97±4.64) and Tie-2(133.89±6.86) in the experimental group were remarkably higher than that in the control group(Ang-1 was 62.83±3.20, Tie-2 was 68.33±5.90). And the MVD between the experimental group(13.83±5.10) and the control group(7.65±3.49) was statistically significant(P<0.05). The expression of Ang-1 had no significant correlation with MVD(r=0.39,P>0.05), but the expression of Tie-2 was positively correlated with MVD(r = 0.71,P < 0.05). ConclusionsActive angiogenesis take place in esophagus of rats with portal hypertension. The expression of Ang-1, Tie-2 and CD34 is obviously higher in lower esophagus of rats in experimental group than that in the control group. The activation of Tie-2 is possibly related to the neoangiogenesis in lower esophagus of rats with portal hypertension.