Controlled arterial reflow after ischemia induces better outcomes in the juvenile rat brain

Abstract

Our objective was to determine whether controlled reflow on one side and/or the other side after bilateral carotid occlusion release could reduce cell death in focal ischemic P14 rats. Arterial blood flow was measured using ultrasonography. Cell death, inflammation and nitrotyrosine were measured using immunofluorescence. When reflow was first induced in the contralateral side, we observed improved outcome markers compared with those when reflow was first induced in the ipsilateral side and/or simultaneous reflow was induced in both sides. Our data suggest that progressive rerouting of arterial flow through the circle of Willis toward the ischemic site reduced cell death.

Keywords: Ischemic stroke; arterial re-flow; cell death; macrocirculation.

Figure 1.

Blood flow redistribution in the three great arteries of the circle of Willis after the transient CCA occlusion release protocols. (a–c) Mean BFV in the basilar trunk (BT, a), the right ICA (rICA, b), and left ICA (c) in the control (white bars, simultaneous CCAs occlusion release, n = 6), R-L (gray bars, n = 7), and L-R (black bars, n = 7) groups under basal conditions, at end of ischemia (Isch), after the first CCA release (R1), after the second CCA release (R2 – 5 min later), and after 15 min of re-flow. ***p < 0.001 (vs. basal); ^##p < 0.01, ^###p < 0.001 (control vs. R-L); ^‡p < 0.05, ^‡‡‡p < 0.001 (R-L vs. L-R).

Figure 2.

COX-2 and mPGES-1 gene and protein expression, nitrotyrosine formation and cell death. (a–d) Quantification for the COX-2 and mPGES1 genes (a–b) and proteins (c–d) in the three groups of animals (n = 6 per group) in the left (IL) and right (CL) cortex. (e–f) Quantification of microglial cells (immunostained with Iba-1) in the IL cortex at 4 (e, n = 10) and 24 (f, in remote peri-infarct, n = 10) hours after reflow. (g) Quantification of 3-nitrotyrosine (3-NT) formation at 24 h after reflow. (h–i) Number of cleaved-caspase-3⁺-cells in the ipsilateral peri-infarct in the three groups of animals at 24 h after reflow. CL: contralateral; IL: ipsilateral; Cy: cytoplasm; Nu: nuclear. *p < 0.05, **p < 0.01, and ***p < 0.001 vs. control. ^#p < 0.05, ^##p < 0.01, ^###p < 0.001 R-L group vs. L-R group.