Effect of EA preconditioning on SDF-1α expression in ischemic brain. (A) Representative immunohistochemical staining showed SDF-1α-positive cell expression 24 h after occlusion in the ischemic cortex of mice that received control or EA. The blue rectangle represents the imaging field. Quantification of SDF-1α-positive cells is expressed as the % change of the control. The results are expressed as mean ± SEM for three mice in each group. *, P<0.05 vs. control (Con). (B) Representative double immunofluorescence staining for SDF-1α (red) and CD31 (endothelial cell marker, green) in EA-preconditioned ischemic brain. EA-induced SDF-1α was colocalized with the endothelium after ischemic injury. Scale bar = 100 μm.