| Objective: Abdominal Aortic Aneurysm(Abdominal Aortic Aneurysm,AAA)refers to the chronic Abdominal aorta rational change,usually defined as greater than 50% of the normal diameter(or greater than 30 mm),is a kind of serious vascular surgical disease,known as the "time bomb" in the body.Once rupture occurs,the mortality rate is as high as more than 80%,ranking the 13 th among all causes of death,and one of the leading causes of death in the elderly.At present the main treatment is surgery,including Endovascular aortic aneurysm repair(EVAR)and abdominal aortic aneurysm resection and artificial vascular replacement,usually when abdominal aortic aneurysm surgical intervention > 5.5 cm in diameter.For patients who do not meet the surgical indications,relevant studies have shown that early surgical intervention does not improve their prognosis.Currently,smoking cessation,blood pressure control and follow-up observation are recommended in clinical practice.As the patient ages and the physical condition declines,the risk of surgery will multiply.It makes more sense to seek a more aggressive,noninvasive approach to inhibit aneurysm dilation,prevent rupture,or reduce rupture risk in small AAA patients.At present,many studies have shown that the small AAA period is the best time for drug control,but there is no clear and effective therapeutic drug in clinical practice.Therefore,it is of great clinical significance to explore the pathogenesis of AAA and find effective drugs to "take the initiative".Existing studies have shown that destructive remodeling of the extracellular matrix,chronic inflammatory responses,structural changes in arterial walls,and dysfunction of vascular smooth muscle cells are the major pathologic changes of AAA.Vascular smooth muscle cell(VSMC)is an important part of the arterial wall.VSMC has systolic phenotype and synthetic phenotype.Systolic phenotype plays an important role in maintaining the normal elasticity and function of the vascular wall.When stimulated by the outside world,the systolic phenotype of VSMC decreases while the synthetic phenotype increases,which is also the basis of many vascular diseases.The essence of AAA is a chronic degenerative disease.Relevant studies have shown that there is always the participation of reactive oxygen species(ROS)and oxidative stress in the occurrence and development of AAA,suggesting that antioxidant may be a potential therapeutic target to inhibit the expansion of AAA.Puerarin,also known as puerarin flavin,has anti-inflammatory,antioxidant and phytoestrogenic activities,which are consistent with the pathological changes of AAA.Keap1-nrf2 signaling pathway plays an important role in endogenous antioxidant,and its downstream antioxidant enzyme plays an important role.Related studies have shown that puerarin can play a role through this pathway.Therefore,the purpose of this study was to study the protective effect of puerarin on abdominal aortic aneurysm dilatation and to verify whether it plays its role through the antioxidant mechanism of keap1-nrf2 signaling pathway.Methods: In this study,SPF male healthy SD rats weighing 250-300 g were randomLy divided into four groups: sham group(S),abdominal aortic aneurysm group(AAA),placebo group(Pl)and puerarin group(Pu).The rat model of subrenal abdominal aortic aneurysm was established by elastase perfusion.A length of about 1 cm below the left renal artery was selected as the perfusion segment.All rats underwent surgery.The sham operation group was perfused with normal saline,and the remaining three groups were perfused with elastase.After continuous administration for 30 days from the second day after operation,Pu group was injected intraperitoneally with puerarin solution 100 mg /Kg / Day,and Pl group and S group were given intraperitoneal injection of Puerarin solution as placebo according to body weight.After 30 days,all rats were re-anesthetized and the specimens were taken again.The abdominal aortic perfusion section was used to extract proteins for Western Blot to detect the expression of TNF-?,NF-?B protein levels,the expression of extracellular matrix metalloproteinases MMP-2 and MMP-9 protein levels,the expression levels of Keap1 and Nrf2 proteins were detected,and the expression levels of antioxidant enzymes HO-1 and NQO-1 proteins were detected.Some of the specimens were used to determine MDA content and SOD activity,and some were used for paraffin embedded sections for HE,EVG and immunofluorescence staining.Arterial blood was drawn to determine MDA content and SOD activity.Results: The diameter of the abdominal aorta of all rats at the time of modeling was 1.17± 0.35 mm.When the material was taken 30 days later,the diameter of the abdominal aorta in the sham operation group was 1.45 ± 0.07 mm and the expansion rate was 23.44± 4.69%.The diameter of the aorta was 4.21 ± 0.58 mm and the dilation rate was 260.6 ±50.01%;the diameter of the abdominal aorta in the placebo group was 4.17 ± 0.22 mm and the dilation rate was 253.6 ± 20.67%;the diameter of the abdominal aorta in thepuerarin-treated group was 2.35 ± 0.19 mm,the expansion rate was 101.8 ± 18.41%.HE staining showed that the vascular wall structure of the abdominal aortic aneurysm model group and the placebo group disappeared,the cells were arranged disorderly,and there was a large number of infiltration of inflammatory cells in the outer layer.The structure of the puerarin-treated group had less infiltration of inflammatory cells.The EVG staining showed that the elastic fiber structure of the abdominal aortic aneurysm model group and the placebo group broke and the elastic fiber structure disappeared,and the elastic fiber of the puerarin treatment group maintained a continuous bending state,but only partially flattened.Western Blot results showed that the expressions of TNF-?,NF-?B,MMP-2,and MMP-9 proteins were stronger in the abdominal aortic aneurysm model group and placebo group than in the puerarin-treated group.The SM22? protein was the opposite,the expression was stronger in the puerarin-treated group than in the abdominal aortic aneurysm model group and placebo group.Immunofluorescence staining showed that compared with the sham operation group,the expression of Nrf2 in the abdominal aortic aneurysm model group and the placebo group was increased,and more expressed in the nucleus.The expression level of the puerarin-treated group was further increased,and almost all were expressed in the nucleus.This is consistent with the Western Blot results.Compared with the sham operation group,the expression of Nrf2 in the nucleus of the abdominal aortic aneurysm model group and placebo group was significantly increased,and the puerarin-treated group was further increased.At the same time,Western Blot results showed that the expression of antioxidant enzymes NQO-1 and HO-1 was consistent with the expression level of Nrf2 in the nucleus.Compared with the sham operation group,the other three groups had higher levels of MDA in arterial tissue and serum.The puerarin-treated group was significantly lower than the abdominal aortic aneurysm model group and placebo group(p <0.01).Compared with the sham operation group,the other three groups had different levels of SOD activity in arterial tissue and serum,and the puerarin-treated group was significantly higher than the abdominal aortic aneurysm model group and placebo group(p <0.01).Conclusion: The results of this study indicate that puerarin treatment effectively inhibits the expansion of abdominal aortic aneurysms in rats,reduces inflammatory response anddegradation of extracellular matrix,maintains elastic fiber structure and functional integrity,and maintains vascular smooth muscle contractile phenotype.Activate the Keap-1 / Nrf2 signaling pathway,promote Nrf2 entry into the nucleus and start the expression of downstream antioxidant enzymes HO-1 and NQO-1,reduce the level of oxidation,enhance the antioxidant capacity,and reduce oxidative stress damage. |
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