Intrathecal DEX shows analgesic property in a α2-R dependent manner via inhibiting spinal ERK1/2 phosphorylation.

<p>(A) Pretreatment with different doses of DEX increased the thermal withdrawal latency and mechanical withdrawal threshold in pH 5.0 PBS mice (***<i>P<</i>0.001, **<i>P</i><0.01 compared with ACSF+pH 7.4 PBS group, $$$<i>P<</i>0.001, $$<i>P</i><0.01, compared with ACSF+pH 5.0 PBS group, n = 8). Pretreatment with atipamezole blocks the effects of intrathecal DEX on pain behaviors (B: ***<i>P<</i>0.001, compared with ACSF+pH 7.4 PBS group, $$$<i>P<</i>0.001, compared with ACSF+PH5.0PBS group, n = 8), spinal p-ERK1/2(C: *<i>P<</i>0.05, n = 6) and c-Fos protein expression (D: **<i>P</i><0.01, *<i>P</i><0.05, scale bar = 100 µm, n = 6). (F) Four paws-holding time 1 minute after intrathecal DEX for 1 min, ***<i>P</i><0.001, n.s. for no significance, n = 10.