Expression of P2Y1 receptors in DRG and spinal cord and effect of the selective P2Y1 receptor antagonist MRS2500 (MRS) in rats subjected to chronic constriction injury (CCI). Time course of the withdrawal threshold observed after CCI (panel A). Expression of P2Y1 receptors in the ipsilateral (IL) dorsal root ganglia (DRG) and dorsal spinal cord (SC) in sham (S) and neuropathic rats at 1, 3, 7 and 14 days after injury (panels B, C and D). Antiallodynic effect of the selective P2Y1 receptor antagonist MRS2500 in rats previously (3 days) subjected to CCI (panel E). Effect of MRS2500 on CCI-induced up-regulation of P2Y1 receptors in DRG of rats previously (3 days) subjected to CCI (panel F). Antiallodynic effect of MRS2500 in rats previously (14 days) subjected to CCI (panel G). Effect of MRS2500 on CCI-induced up-regulation of P2Y1 receptors in DRG of rats previously (14 days) subjected to CCI (panel H). Behavioral and molecular data are expressed as mean ± S.E.M. for 6 and 3 animals, respectively. Data are expressed as the time course of the withdrawal threshold. * p < 0.05, ** p < 0.01 and *** p < 0.001, significantly different from the vehicle (Veh) or Sham (S) group, as determined by one (panels C and D) or two-way (panels E and G) analysis of variance followed by the Dunnett's test or Bonferroni test, respectively. Student t-test was used to compare 2 independent groups.