Intrathecally administered mast cell inhibitors reduce mast cell degranulation but not capsaicin hyperalgesia. Intrathecal cromolyn (200 μg) administered prior to intradermal 1% capsaicin (at timepoints shown by ↑) does not reduce mechanical hyperalgesia (A). There is also no effect of intrathecal cromolyn or BAY-613606 pretreatment on mechanical hyperalgesia (B) induced by 0.2% capsaicin. However, both BAY-613606 and cromolyn significantly reduce increased percent mast cell degranulation induced by 1% capsaicin in the lumbar dura mater (C) (* = P < 0.05 as compared to capsaicin alone), but not in the thoracic dura mater (D). BAY-613606, but not cromolyn, further reduces degranulated and total cell density in the lumbar dura mater (E) (# = P < 0.05 as compared to capsaicin + vehicle) but not in thoracic dura mater (F).