Fig. 4.

Time-effect curves of intrathecal nociceptin/orphanin FQ (N/OFQ) and co-administered naltrindole (NTI) for flinching responses in the formalin test. X-axis: time (min) after formalin injection. Y-axis: number of flinches for each 5-min session. Each value represents mean±SD (n=8). Symbols represent the different dose conditions for each panel. Ten nmol of N/OFQ was administered intrathecally, followed 5 min later by 5, 10, or 20 nmol of NTI and vehicle (0.9% sterile saline), before formalin injection. I.t. co-administration of NTI dose-dependently reversed N/OFQ-induced flinching attenuations in the formalin test (p<0.05). SD, standard deviation.