Suppression of experimental abdominal aortic aneurysm in a rat model by the phosphodiesterase 3 inhibitor cilostazol.

Background: The present experiments sought to determine whether cilostazol, a selective inhibitor of cyclic adenosine monophosphate (cAMP) phosphodiesterase 3 (PDE3), suppressed elastase-induced abdominal aortic aneurysm (AAA) development in a rat model.

Methods: Male Sprague-Dawley rats (n = 16/each group) were randomly distributed into three groups: sham-, saline-, and cilostazol-. Rats of saline and cilostazol groups underwent intra-aortic elastase perfusion to induce AAAs, while rats of sham-group were perfused with saline. Rats of cilostazol-group received cilostazol treatment (100 mgkg(-1)d(-1)) for the entire experimental period. The areas of the lumen of the aortas at the segment with maximum diameter were measured preperfusion and on d 7, 14 after perfusion. Systolic blood pressure was measured by tail-cuff technique. Aortic tissue samples were harvested on d 14 after intra-aortic perfusion and evaluated by reverse transcription-polymerase chain reaction and Western blot for matrix metalloproteinase-2, 9 (MMP-2, 9), by immunohistochemistry for nuclear factor kappa B (NF-κB), and by Gomori aldehyde fuchsin for elastin. Activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and level of reactive oxygen species (ROS) in these samples were also measured.

Results: On d 14, rats of saline-group had significantly increased aortic sizes compared with sham-group (P < 0.01), while, cilostazol treatment significantly reduced this increase (cilostazol- versus saline-, P < 0.01) without affecting blood pressure (P > 0.05). The expression of both MMP-2 and MMP-9 and the destruction of elastic fibers in aortic tissues were significantly decreased by cilostazol treatment (P < 0.05), probably through the suppression of NF-κB activation (P < 0.01). Consistently, cilostazol significantly inhibited NADPH oxidase activity (P < 0.01), accompanied by a reduced level of ROS (P < 0.01).

Conclusion: Cilostazol retards experimental AAAs development independently of blood pressure reduction possibly by inhibiting proteolysis, inflammation, and oxidative stress. Selective PDE3 inhibition may offer an additional method to pharmacologically inhibit AAAs.