Procedural and Strain-related Variables Significantly Affect Outcome in a Murine Model of Focal Cerebral Ischemia

Abstract

The recent availability of transgenic mice has led to a burgeoning number of reports describing the effects of specific gene products on the pathophysiology of stroke. Although focal cerebral ischemia models in rats have been well described, descriptions of a murine model of middle cerebral artery occlusion are scant and sources of potential experimental variability remain undefined. We hypothesized that slight technical modifications would produce widely discrepant results in a murine model of stroke and that controlling surgical and procedural conditions could lead to reproducible physiological and anatomic stroke outcomes. To test this hypothesis, we established a murine model that would permit either permanent or transient focal cerebral ischemia by intraluminal occlusion of the middle cerebral artery. This study provides a detailed description of the surgical technique and reveals important differences among strains commonly used in the production of transgenic mice. In addition to strain-related differences, infarct volume, neurological outcome, and cerebral blood flow appear to be importantly affected by temperature during the ischemic and postischemic periods, mouse size, and the size of the suture that obstructs the vascular lumen. When these variables were kept constant, there was remarkable uniformity of stroke outcome. These data emphasize the protective effects of hypothermia in stroke and might help to standardize techniques among different laboratories to provide a cohesive framework for evaluating the results of future studies in transgenic animals.

The Involvement of Upregulation and Translocation of Phospho-Rb in Early Neuronal Apoptosis Following Focal Cerebral Ischemia in Rats

“…Middle cerebral artery occlusion (MCAO) was performed as previously described [14,15] with slight modification. Briefly, the right common carotid artery (CCA), external carotid artery and internal carotid artery were exposed through a midline cervical incision.…”

Reduced microvascular thrombosis and improved outcome in acute murine stroke by inhibiting GP IIb/IIIa receptor-mediated platelet aggregation.

“…Before giving anesthesia, mice were examined for neurological deficit 23 h after reperfusion using a four-tiered grading system: a score of 1 was given if the animal demonstrated normal spontaneous movements; a score of 2 was given if the animal was noted to be turning towards the ipsilateral side; a score of 3 was given if the animal was observed to spin longitudinally (clockwise when viewed from the tail); and a score of 4 was given if the animal was unresponsive to noxious stimuli. This scoring system has been previously described in mice (4,5), and is based upon similar scoring systems used in rats (19).…”

“…Although fragments of lipid-laden, platelet-, and fibrin-rich debris can also migrate downstream beyond the site of the original occlusion, it is possible that in situ microvascular thrombosis may be triggered as well at these downstream sites, perhaps accounting for the observed accumulation of thrombotic material in branches of the microcirculation in a primate model of stroke (1)(2)(3). Additional evidence also supports this possibility, in that, in a murine model of stroke induced by temporarily obstructing a major vascular tributary with a nylon suture that is subsequently removed, cerebral blood flow (CBF) 1 does not return to preischemic levels after removal of the obstructing suture (4)(5)(6). Although neutrophilcapillary plugging is an important contributor to postischemic cerebrovascular no reflow, preischemic depletion of neutrophils (5) or blockade of specific neutrophil adhesion receptors (6) does not completely prevent postischemic no-reflow.…”

The two-pore domain potassium channel KCNK5 deteriorates outcome in ischemic neurodegeneration

“…Laser Doppler flowmetry (Moore Instruments) was performed in C57BL/6 WT and Kcnk5 −/− mice at baseline (before ischemia), 10 min after inserting the occluding filament (ischemia) and 10 min after removing the occluding filament (reperfusion) [22]. The regional cerebral blood flow was measured in the territory of the right middle cerebral artery (6 mm lateral and 2 mm posterior from bregma) (Fig.…”