The role of estrogen in the formation of experimental abdominal aortic aneurysm

OBJECTIVE: The current study sought to investigate the role of estrogen in the formation of experimental abdominal aortic aneurysm (AAA). METHODS: Elastase perfusion of infrarenal AAA animal model was performed in 20 female and 20 male Wistar rats that were randomly divided into,in ovariectomized/sham-operated group and an estradiol (E2) experimental/saline control group, respectively. At day 14, E2 was detected, while the mRNA and protein expressions of matrix metalloproteinases 2 and 9 (MMP-2 and -9) in AAA tissue were detected by immunohistochemistry and polymerase chain reaction (PCR). RESULTS: The ovariectomized group showed lower estrogen levels and a higher aneurysm dilatation rate and significantly higher MMP-2 and -9 expression compared with the sham-operated group (P<.01), which was in accordance with MMP-2 and -9 mRNA expression. The E2 group showed higher estrogen levels and a lower aneurysm dilatation rate and significantly lower MMP-2 and -9 expression than did the saline control group (P<.01), which was in accordance with MMP-2 and -9 mRNA expression. CONCLUSIONS: In the pathogenesis of AAA, estrogen may play an inhibitory role by decreasing expression of MMP-2 and MMP-9 synthesis. (C) 2009 Elsevier Inc. All rights reserved.