Antinociceptive effects of acute injection of NT agonists on formalin induced pain behaviors. (a) Time course of analgesic effects of NT (6 μg/kg) and NT69L (5 μg/kg). Saline and drugs were intrathecally administered 5 min before the subcutaneous injection of formalin. Nocifensive behaviors in male rats are expressed in 3 min intervals with a weighted pain score. (b, c) Pre-treatment with JMV-431 (5–60 μg/kg) or levocabastine (0.5–5 μg/kg) results in the inhibition of the persistent noxious chemical stimulation. Each symbol represents the mean ± SEM of determinations made in six to eight animals.