Increased TNF-alpha content in the IA lesion. (A) Immunohistochemistry to detect TNF-alpha in IA walls located at right anterior cerebral artery-olfactory artery bifurcations in a rat model. Immunohistochemistry to detect TNF-alpha in control arterial and IA walls from rats, 3 months after aneurysm induction, is shown. The white arrow and arrow head indicate positive staining in endothelial cells and outer membranes, respectively. The star in the left panel indicates the media of arterial walls. Bar = 50 um. In the right panel, the relative intensities of positive signals in IA walls from the left panel are shown. n = 3 in each group, and *indicates p < 0.05. All bars indicate the mean ± SEM. (B) Increased TNF-alpha content in intracranial arteries after aneurysm induction. TNF-alpha content was analyzed by multi-suspension array using intracranial arteries from rats at indicated time points after aneurysm induction. n = 6 in each group. All bars indicate the mean ± SEM, and *indicates p < 0.05. M; month after aneurysm induction. (C) Enhanced tumor necrosis factor alpha converting enzyme (TACE) activity in intracranial arteries after aneurysm induction. TACE activity was measured as explained in the Methods section. n = 4 in both groups. All bars indicate the mean ± SEM, and *indicates p < 0.05. M; month after aneurysm induction.