Reversal of LTP of C-fiber-evoked field potentials in the dorsal horn of anesthetized mice by RS504393 (45 μg, 15 μL, i.t.), administered 2 h after LTP induction. Spinal LTP was induced by tetanic stimulation (100 Hz, 1 s, 4 trains) of C-fiber intensity in C57/B6 mice. *P < 0.05, vehicle (10% DMSO) vs RS504393, two-way ANOVA, n = 5 mice/group.