Effect of intraplantar or intrathecal injection of kisspeptin or the GPR54 antagonist, p234, in the formalin test. Data obtained with intraplantar (i.pl.) injection of kisspeptin (1 or 3 nmol/5 μl) or p234 (0.01 or 0.1 nmol/5 μl) on the first (0-10 min) and second (15-45 min) phases of the formalin test are shown in (A) and (B), respectively. Drugs were injected 15 min prior to the intraplantar injection of formalin. Data obtained with intrathecal (i.t.) injection of kisspeptin (0.5 or 1 nmol/3 μl) or p234 (0.1 or 1 nmol/3 μl) are shown in (C) and (D), respectively. Data are means + S.E.M. of 8-12 mice per group. *p < 0.05 vs. the respective groups of mice injected with vehicle (one-way ANOVA followed by Fisher's post hoc test).