SMALL REDUCTION OF CAPSAICIN-INDUCED NEUROGENIC INFLAMMATION IN HUMANFOREARM SKIN BY THE GLUCOCORTICOID PREDNICARBATE

Capsaicin applied to human skin provokes a response known as neurogeni c inflammation. Neuropeptides (substance P, CGRP), released from affer ent C-fiber terminals and histamine, secondarily released from mast ce lls, are supposed to participate in this reaction. We investigated the contribution of arachidonic acid and metabolic products to neurogenic inflammation, using a potent topically applied glucocorticoid and the corresponding vehicle. Arachidonic acid is liberated from membrane ph ospholipids by phospholipase A2, an enzyme that can be blocked by gluc ocorticoids. In 12 healthy volunteers, neurogenic inflammation was ind uced by capsaicin 1% on both upper forearms after 16 h of topical pret reatment with either prednicarbate or vehicle. Neurogenic inflammation was assessed by laser Doppler flowmetry and by planimetry of flare si zes. Prednicarbate significantly reduced the laser Doppler flow values inside the flare responses, as well as the flare sizes themselves. Th ese results show that to some extent glucocorticoids reduce capsaicin- induced neurogenic inflammation.