Fig. 4.
Capsaicin (cap)-treated mice exhibit a complete and selective loss of heat pain sensitivity. Latency to lick or jump on 55 °C hot plate 1 day after intrathecal (i.t.) injection of cap or vehicle (veh) (P̂ < 0.0001, Student's t test) (A) and at weekly intervals after injection of cap (n = 4) (B). (C) CFA-induced heat hypersensitivity (**, P < 0.01, P̂ < 0.0001, two-way repeated measures ANOVA with Bonferroni posttest). (D) Temperature preference assay (**, P < 0.01, Student's t test). (E) Fos induced by hind paw immersion in 55 °C water bath. (F) Fos+ neurons in laminae I/II and V per 40-μm section (**, P < 0.01, Student's t test; n = 3 per group). (G) Mechanical threshold (von Frey test). (H) CFA-induced mechanical hypersensitivity (P̂ < 0.0001, two-way repeated measures ANOVA with Bonferroni posttest). Data represent mean ± SEM. Unless otherwise noted, n = 8–10.