Figure 6. Rapamycin blocks capsaicin-induced secondary mechanical hyperalgesia but not primary hyperalgesia.

A, Effect of rapamycin or vehicle on withdrawal latency to heat after capsaicin. Rapamycin or vehicle were injected intraplantar 4 h before capsaicin administration. All injections were made in the center of the plantar surface of the paw. B, C, Secondary mechanical hyperalgesia in the lateral plantar hindpaw was generated by injecting capsaicin into the central plantar surface of the hindpaw. Rapamycin or vehicle pre-treatment was delivered intraplantar in the lateral part of the surface of the hindpaw 4 h before capsaicin injections (see inset diagrams). B, Effect of lateral intraplantar injection of rapamycin or vehicle on mechanical withdrawal threshold on central plantar injection of capsaicin using Von Frey hairs. C, Effect of rapamycin or vehicle on withdrawal response duration to pinprick stimulation after capsaicin. Mean±SEM for the injected (left) hindpaw is illustrated in each panel. M, medial; L, lateral. *** P<0.001.