Intraplantar injection of kisspeptin lowers pain threshold in the hot plate. The nocifensive response to intraplantar injection of kisspeptin (3 nmol/5 μl) in naïve mice is shown in (A). Data are means ± S.E.M of 6 mice, and refer to the number of sec spent in licking behavior in the first 5 min following injection. *p < 0.05 (Student's t test) vs. mice injected with vehicle. Data obtained in the hot plate test are shown in (B). For each animal, the percentage maximum possible effect (%MPE) was calculated using the following formula: [(post-drug latency) - (pre-drug latency)/(cutoff time) - (pre-drug latency)] × 100. Data are means ± S.E.M. of 6 to 8 mice. *p < 0.05, two-way ANOVA followed by Fisher's post hoc test. PWL, Paw-withdrawal latency.