Objective：To study the effect of  benazepril on abdominal aortic aneurysm(AAA) formation and the possible mechanism.
Methods：Twenty-four healthy male rabbits were randomly divided into three groups according to perfusion fluid(saline, elastase, and benazepril-treated elastase groups). The diameter of the aorta was measured, and the aortic tissue was excised for histologic examination using HE and VG stain. Total protein of matrix metalloproteinases-9(MMP-9) was measured by Western Blot test. MMP-9 mRNA of aorta was detected by RT-PCR. MMP-9 protein activity was detected by Gelatin zymography.
Results：Seven days after perfusion,the average dilation rate of the three groups was 7.50%（saline perfusion group,group A）,120.62%（elastase perfusion group,group B） and 39.20%（benazepril-treated elastase perfusion group,group C）respectively. The result showed that benazepril had an obvious inbitiory effect on AAA formation. The elastic fiber content was conserved better in group C than in group B（P<0.01）,meanwhile benazepril effectively inhibited inflammation infiltration.MMP-9 expression and activity was enhanced in group B,while group C showed weakened MMP-9 protein and mRNA expression（P<0.01）. MMP-9 activity in group C was also significantly decreased（P<0.01）.
Conclusions：Benazepril could obviously inhibit AAA formation in rabbit models.The mechanism may relate to inhibition of inflammation infiltration, down-regulation of extracellular matrix degeneration in multiple levels and preservation of elastic fiber.