Intraluminal suture occlusion and ligation of the distal branch of internal carotid artery: An improved rat model of focal cerebral ischemia-reperfusion

In order to evaluate a modified method of reversible middle cerebral artery occlusion (MCAo), 50 male Sprague–Dawley rats were subjected randomly to reperfusion series (n = 30) with 3 h of MCAo followed by 69 h of reperfusion and permanent series (n = 20) with 24 h of MCAo only. Based on Longa's method, experimental group with ligation of the distal branch of the internal carotid artery (ICA) around the intraluminal suture and control group without ligation were included. Behavioral functions were evaluated at 3 h after occlusion and during a 3-day period after MCAo in reperfusion series, or at 3 and 24 h after occlusion in permanent series. Infarct volume (IFV) was measured by the 2,3,5-triphenyl tetrazolium chloride (TTC) method at end time point in each series, and intraluminal thrombus formation in ICA of the reperfusion series was evaluated. In the experimental groups, a 100% incidence of infarction was shown in two series which was significantly higher than that in the control group (40% in reperfusion series and 50% in permanent series, p < 0.05). The total IFV and subcortical IFV in the experimental group was 174.9 ± 6.2 and 101.8 ± 2.6 mm3 in reperfusion series and 321.8 ± 4.2 and 191.6 ± 7.5 mm3 in permanent series, respectively, significantly larger than that in the control group (p < 0.05). Meanwhile, the coefficient of variation of total IFV and subcortical IFV in the experimental group was dramatically smaller than that in the control group (p < 0.05). Rats in the experimental groups were more severely impaired on neurobehavioral tests than that in the control groups (p < 0.05), and showed longer duration of neurological deficits and slower recovery of functions. No thrombus or clot was observed in ICA of the reperfusion series. Reversible MCAo with ligation of the distal branch of ICA is proven to be a reliable and effective method with which consistently larger infarcts including subcortex lesions is yielded.