The partial inhibition of inflammatory responses induced by capsaicin using the Fab fragment of a selective calcitonin gene-related peptide antiserum in rabbit skin.

The effect of an anti-calcitonin gene-related peptide (CGRP) antibody on responses induced by the sensory C-fibre neuropeptide, CGRP, and capsaicin, which selectively activates C-fibre nerves, was investigated in rabbit skin. Test agents and antibody were injected intradermally. Local blood flow changes were measured by 133Xenon clearance and oedema formation by [125I]albumin accumulation. Preinjection intradermally with the Fab fragment of a goat anti-human alpha CGRP antibody selectively inhibited increased blood flow induced by CGRP (3 x 10(-12) mol/site) and caused a partial, but significant inhibition of increased blood flow induced by capsaicin (3 x 10(-7) mol/site). Oedema induced by histamine and bradykinin was potentiated by vasodilator doses of CGRP and capsaicin. These potentiating effects were significantly inhibited by pretreatment with anti-CGRP Fab. The Fab fragment was more potent in inhibiting capsaicin-induced responses than the parent IgG. These results suggest that capsaicin releases vasodilator quantities of CGRP in rabbit skin.