Figure 7.

Spinal infusion of the P2Y₁₂ agonist 2Me-SADP induced pain behavior and phosphorylation of p38 MAPK. A, B, Spinal infusion of 2Me-SADP (1 nmol/h) induced mechanical allodynia (A) and thermal hyperalgesia (B). However, the P2Y₁₂ antagonist MRS2395 (100 pmol/h) and p38 MAPK inhibitor SB203580 for 3 d reversed the effect of 2Me-SADP on pain behaviors. Values are represented as mean ± SEM (n = 8 in each group, *p < 0.05; ^# p < 0.001). C–F, IHC shows the expression of phospho-p38 immunoreactivity in the spinal dorsal horn. Rats received intrathecal administration of vehicle (C), the P2Y₁₂ agonist 2Me-SADP (D), both 2Me-SADP and MRS2395 (E), and MRS2395 alone (F). Scale bar, 100 μm. G, Quantification of immunostaining intensity of phospho-p38 MAPK determined as the average pixel density in the ipsilateral dorsal horn 3 d after injury. H, Quantification of the numbers of p-p38-immunoreactive cells in the ipsilateral dorsal horn 3 d after injury. Data represent mean ± SEM; n = 4 per group. ^# p < 0.001.