Background and purpose: Rupture of cerebral aneurysm (CA) is the major cause of subarachnoid hemorrhage. Molecular mechanisms of this disease, however, remain unknown. To make possible genetic analysis of CA formation with genetically altered mice, we have successfully established a mouse model of saccular CA that recapitulates the essential features of human saccular CA.
Methods: In C57black/6 male mice, various stages of CAs were experimentally induced at the right anterior cerebral artery-olfactory artery bifurcations by ligations of left common carotid arteries and posterior branches of bilateral renal arteries with high salt diet. Both light and electron microscopic studies were performed with the longitudinal sections of anterior cerebral artery-olfactory artery bifurcations.
Results: In the treated group, various aneurysmal changes were detected in 14 of 18 mice. On the other hand, in the control group, no aneurysmal changes were found in 15 mice. In microscopic studies, aneurysmal changes were shown to include mainly fragmentation of internal elastic lamina, thinning of the smooth muscle cell layer, and degeneration of adventitial tissue, which were very similar to critical changes in human saccular CA.
Conclusions: This mouse model of CA will be useful for studying the effects of complex determinants on CA formation and makes it possible to understand the pathogenesis of CA at the molecular level.