Fig. 4

a Effect of pretreatment with intraperitoneal (i.p., 60 μmol/kg) ER819762 or intravenous (i.v., 30 μmol/kg) Ro1138452 on the spontaneous nociceptive behaviour evoked by periorbital (p.orb., 10 μl/15 nmol/site) injection of PGE₂. b Dose- and time-dependent periorbital mechanical allodynia (PMA) evoked by p.orb. Injection of PGE₂ (10 μl/0.15–15 nmol/site). c Effect of pretreatment with ER819762 (i.p., 60 μmol/kg) and Ro1138452 (i.v., 30 μmol/kg) on PMA evoked by PGE₂ (p.orb., 10 μl/1.5 nmol/site). d, e Effect of pretreatment with p.orb. (10 μl/10 nmol/site) or intraplantar (i.pl., 20 μl/10 nmol/site) ER819762 on PMA evoked by PGE₂ (p.orb., 10 μl/1.5 nmol/site). f PGI₂ (p.orb., 10 μl/15 nmol/site) does not evoke spontaneous nociceptive behaviour. g Dose- and time-dependent PMA evoked by PGI₂ (p.orb., 10 μl/0.15–15 nmol/site). h Effect of pretreatment with Ro1138452 (i.v., 30 μmol/kg), and ER819762 (i.p., 60 μmol/kg) on PMA evoked by PGI₂ (p.orb., 10 μl/1.5 nmol/site). i, j Effect of pretreatment with p.orb. (10 μl/10 nmol/site) or i.pl. (20 μl/10 nmol/site) Ro1138452 on PMA evoked by PGI₂ (p.orb., 10 μl/1.5 nmol/site). k PGF_2α (p.orb., 10 μl/1.5–15 nmol/site) does not evoke spontaneous nociceptive behaviour or PMA. C57BL/6J mice were used. Veh is the vehicle of PGE₂ (a-e), PGI₂ (f-j) or PGF_2α (k) and veh1 is the vehicle of ER819762 (d, e), Ro1138452 (i, j) or a combination of vehicles of ER819762 and Ro1138452 (a, c, h). Arrows indicate time of PGE₂, PGI₂ or PGF_2α administration. ER819762 and Ro1138452 were given 30 min before PGE₂ or PGI₂. Error bars indicate mean ± s.e.m., n = 6 mice per group. *P < 0.05 vs. Veh or Veh + Veh1, ^§P < 0.05 vs. Veh1 + PGE₂ or Veh1 + PGI₂; one- or two-way ANOVA with Bonferroni post hoc correction