Fig 2.

Dexmedetomidine reduces damage and protects spinal tissue at injury site after spinal cord injury (SCI). SD, SCI+dexmedetomidine (DEX); SDY, SCI+dexmedetomidine+yohimbine (Yoh). (a) DEX reduced maximal injury areas and spared white matter at the SCI epicentre. Eriochrome cyanine (EC) staining was used to assess the severity of spinal tissue injury at the epicentre. The size of the lesion volume and spared tissue was quantitated at the section with maximal injury. Microscopic images (4×) show representative sections in each treatment group (1–3). The lesion volume was significantly reduced (4), and there was more spared spinal tissue (5), especially white matter, in the SD group (6; **P<0.01; one-way analysis of variance (anova) with Tukey's test; n=8–10 in each group). Pretreatment with an α2 antagonist (SDY) partially reduced the spared white matter by DEX (6; *P<0.05; one-way anova with Tukey's test; n=8–10 in each group). Because of the large within-group variation, DEX had no significant effect on grey-matter sparing (7). (b) DEX decreased the lesion volume from rostral-to-caudal direction. Rostro-caudal sections were quantitated by EC staining for lesion size (–960, –720, –480, –240, 0, 240, 480, 720, and 960 μm). The sizes of injury areas at the indicated distances from the epicentre (distance=0 μm) were significantly reduced in the SD group compared with SCI (SCI vs SD; P<0.001; two-way anova with multiple comparisons; n=8–10 in each group). Pretreatment with an α2 antagonist (Yoh) led to partial reversal of the DEX effect on tissue protection (SD vs SDY; P<0.001; two-way anova with multiple comparisons; n=8–10 in each group). Ips, ipsilateral; Cnt, contralateral; WM, white matter; GM, grey matter.