E‐52862 reduces osteoarthritic pain‐facilitated firing frequency of WDR spinal neurons. (a) Extracellular recordings were assessed from ipsilateral WDR neurons in the lamina 5 of the dorsal horn. The receptive field in the hind paw was stimulated using von Frey filaments, dynamic brush, static pressure (pinch), and heat (48°C). (b) MIA injection facilitated the evoked responses to punctate mechanical stimuli. (c) Firing frequency evoked by brush, pinch, or heat was similar in MIA and sham‐injected animals. (d,e) 90 μg of E‐52862 significantly reduced the evoked responses to mechanical and thermal stimuli 30 min after intrathecal application in mice with osteoarthritis pain. (f,g) Application of 180 μg of E‐52862 inhibited the firing frequency in response to stimulation of the hind paw 10 and 30 min after administration. Stimuli were applied for 10 s, and responses are presented as mean ± SEM. Histogram traces for single unit responses of WDR neurons representative for each group are presented. The number of animals is the following: sham‐vehicle = 4; MIA‐vehicle = 8; and MIA‐E‐52862 (10 and 30 min) = 6. Panels (d) and (f): *P<.05, significant difference between MIA‐E‐52862 (10 and 30 min) and MIA‐vehicle (F test of non‐linear regression) and +P<.05, significant difference between MIA‐E‐52862 and MIA‐vehicle (two‐way repeated‐measures ANOVA plus Fisher least significant difference test). Panels (e) and (g): # P<.05, significant difference between MIA‐E‐52862 and MIA‐vehicle (two‐way repeated‐measures ANOVA plus Fisher least significant difference test). MIA, monoiodoacetate