A reproducible model of global cerebral ischemia in mice is essential for elucidating the molecular mechanism of ischemic neuronal injury. Such a model is particularly important in the mouse because many genetically engineered mutant animals are available. In C57BL/6 and SV129/EMS mice, we evaluated a three-vessel occlusion model. Occlusion of the basilar artery with a miniature clip was followed by bilateral carotid occlusion. The mean cortical cerebral blood flow was reduced to less than 10% of the preischemic value, and the mean anoxic depolarization was attained within 1 minute. In C57BL/6 mice, there was CA1 hippocampal neuronal degeneration 4 days after ischemia. Neuronal damage depended upon ischemic duration: the surviving neuronal count was 78.5 +/- 8.5% after 8-minute ischemia and 8.4 +/- 12.7% after 14-minute ischemia. In SV129/EMS mice, similar neuronal degeneration was not observed after 14-minute ischemia. The global ischemia model in C57BL/6 mice showed high reproducibility and consistent neuronal injury in the CA1 sector, indicating that comparison of ischemic outcome between wild-type and mutant mice could provide meaningful data using the C57BL/6 genetic background. Strain differences in this study highlight the need for consideration of genetic background when evaluating ischemia experiments in mice.

Although p53 controls cell death after various stresses, its role in neuronal death after brain ischemia is poorly understood. To address this issue, we subjected p53-deficient (p53 À/À and p53 + /-) mice (backcrossed for 12 generations with C57BL/6 mice) and wild-type mice (p53 + / + ) to transient global ischemia by the three-vessel occlusion method. Despite similar severity of ischemia, as shown by anoxic depolarization and cortical blood flow, neuronal death in the hippocampal cornus ammonis (CA)1 region was much more extensive in p53 + / + than in p53 À/À mice (surviving neuronal count, 9.3%63.0% versus 61.3%634.0% of nonischemic p53 + / + controls, respectively, P < 0.0037). In p53 + /À mice, a similar trend was also observed, though not statistically significant (43.5% of nonischemic p53 + / + controls). In p53 + / + mice, p53-like immunoreactivity in hippocampal CA1 neurons was enhanced at 12 h after ischemia, and messenger ribonucleic acid for Bax, a direct downstream target of p53, was also increased. These results indicate that p53 potentiates ischemic neuronal death in vivo and suggest that this molecule could be a therapeutic target in neuronal death after cerebral ischemia.

Rapid clot removal and clearance has been proposed as an effective tool for preventing cerebral vasospasm after subarachnoid hemorrhage (SAH). We examined the relationship between clot-clearance rate and the severity of cerebral vasospasm in 110 consecutive patients with aneurysmal SAH. We measured clot-clearance rates per day in the basal and Sylvian cisterns, and evaluated the presence of symptomatic vasospasm based on changes in clinical symptoms and the appearance of a new low-density area on a computed tomography (CT) scan. The severity of symptomatic cerebral vasospasm was associated with age and the SAH grade on admission; however, we observed no significant difference between these variables in patients with urokinase irrigation or fasudil hydrochloride treatment. The mean clot-clearance rates per day for patients with asymptomatic and permanent delayed ischemic neurological deficit were 41.9 and 41.5 %, respectively, in the basal cistern (P = 0.7358) and 37.7 and 23.9 %, respectively, in the Sylvian cistern (P = 0.0021). The reduced clot-clearance rate in the Sylvian cistern increased the risk of vasospasm-related infarction (P = 0.0093) and markedly reduced unfavorable outcomes (P = 0.0115).