Microglial activation is mitigated by dexmedetomidine (DEX) at the injury site 28 days after spinal cord injury (SCI). SD, SCI+DEX; SDY, SCI+DEX+yohimbine. CD11b-positive cells (microglia) are shown in spinal injured rats treated with saline (SCI: A, C, and E) or DEX (SD: B, D, and F). Images C and D are cross sections at the SCI epicentre, images A and B are sections 480 μm rostral to the epicentre, and images E and F are 480 μm caudal. Signals of CD11b-positive cells were decreased after DEX treatment (SD) compared with the vehicle control group (SCI). The decrease was statistically significant at 480 μm both rostrally (image A vs B) and caudally (image E vs F) to the injury epicentre (G: SCI vs SD; *P<0.05 by two-way ANOVA with multiple comparisons; n=6 in each group). The total count of CD11b-positive signals across the five different locations suggests a significant reduction of activated microglia in the SD group (H, *P<0.05; Student's t-test; n=6 in each group).