Effects of spinal cord application of vehicle (0.05% DMSO in aCSF) or SA (50 μg/10 μl) on the onset (A), duration (B) and evoked frequency (C) of NS neurons in mice which received saline or formalin injection into the hind-paw. Vehicle or SA were administered 3 days after saline or formalin as indicated by black arrows. Each point represents the mean ± S.E.M of 6–8 neurons of different treated groups of mice. # indicates significant differences vs veh/form. P values <0.05 were considered statistically significant (one-way ANOVA followed by Student-Newman Keuls). Representative ratemeters (D and E) show the responses to a noxious stimulation (von Frey filaments 97.8 mN/2 sec) of a single NS neuron both before and after vehicle or SA spinal application. Grey arrow indicates vehicle or SA application, while black triangle indicate the noxious stimulation on the mouse hind-paw.