Interactions Between Smoking And Plant Polyphenol In The Development Of Rat Abdominal Aortic Aneurysm

The factors which affect the formation and development of abdominal aorticaneurysm(AAA) is complicated and involve multiple genetic and environmental aspects.However, its‘specific etiology and pathology are still not clear. But the destruction ofthe arterial wall matrix, the degradation of collagen fibers and elastin fibers is animportant reason. Epidemiological studies found that smoking play an important role inthe formation, development and rupture of AAA, but the biological pathways of howsmoking affect AAA is not yet clear.1,2,3,4,6-Penta-O-galloyl-beta-D-glucopyranose(pentagalloyl glucose, PGG) is a plant tannin, with the role of protein binding andprevents elastin degradation and to protect the aortic wall. In this study, we will use afactorial experimental design, set PGG and smoking as two treatment factors, observeboth for the individual effects and the interactions to abdominal aortic aneurysmexpansion. For we already knows how PGG protect the elastin fibers of the arterial wall,thus based on the interaction of the two factors, we can indirectly explore whethersmoking have the same biological pathways of PGG then provide experimentalreference for the biological pathways study.Objective:Animal experimental study the separate roles and interaction of smoking and PGGin the process of the formation of abdominal aortic aneurysm. Through the changes ofthe diameter of the rat artery, the artery open angle and the arterial wall pathology, wewill verify the protective effect of abdominal aortic aneurysm from PGG, and probe howsmoking acts in Abdominal Aortic Aneurysm formation.Methods:We select S-D rat as the experimental subjects. AAA were produced by CaCl2incubation. Animals were randomized with2×2crossover design. The processingfactors are smoking and PGG incubation. Thus there are four groups: Smoking group(NS group), Smoking plus PGG group(PS group), PGG group(PN group), Controlgroup(NN group). The rats underwent laparotomy after four weeks of smoking orcontrol treatment. The abdominal aorta diameter and open angle were measured. Takethe sample of abdominal aorta, and use hematoxylin-eosin staining and elastic fiberstaining to show the pathology of the aorta. Use Immunohistochemistry staining toobserve the distribution of MMP-2and MMP-9(matrix metalloproteinase) in all fourgroups.Result:We have done AAA model surgery for60rats, and successfully established AAAmodel in49rats. After intervene as planed, we obtained49samples of rat abdominalaorta in all4groups. Vivo measurement of the diameter and the open angle of theabdominal aorta were statistically analyzed:(1) The average abdominal aortic diameterand open angle of the smoking group is the maximum of the four groups，which was notstatistically significant.(2) The group with only PGG incubation have the minimumaverage aortic diameter and open angle, which was statistically significant.(3) Theinteraction of smoking and PGG was not statistically significant. The staining results ofthe abdominal aorta were as follows:(1) Hematoxylin-eosin staining shows theadventitia of the abdominal aorta grow thicker and the media is widened. Inflammatorycell infiltrate in the media and adventitia.(2) The elastin fiber staining shows the elastinfiber of PGG group and PGG plus smoking group are more intact, have better continuityand fewer fracture, while the fracture in smoking group is quite serious.(3) Theimmunohistochemical staining shows MMP-2mainly distribute in the media andadventitia, especially in the smoking group. MMP-9distribute in the adventitia and theintimal side of media. Most of the media contains little MMP-9.Conclusion:The PGG adventitia incubation has a significant protective effect on ratCaCl2-induced AAA model, it decreases abdominal aortic diameter and open angle, andthe elastic fiber staining shows continuity of the elastin fibers of the arterial wall arebetter. It is able to observe the difference of aortic diameter and open angle caused by short-term smoking, short-term smoking and PGG’s interactions between the groups,but not statistically significant. Elastin fiber staining shows the elastin fibers seriousfracture in the smoking group, and immunohistochemical staining shows that MMP-2accumulation in the media and adventitia in the arterial wall, suggesting smoking dohave impact on experimental rat AAA. We expect expand the duration of smoking andincrease the amount of animals to discuss the affect of smoking and PGG in follow-upexperiment...