The calcitonin gene-related peptide (CGRP) antagonist CGRP 8–37 blocks vasodilatation in inflamed rat skin: involvement of adrenomedullin in addition to CGRP

Abstract

The neuropeptide calcitonin gene-related peptide (CGRP) is a potent microvascular vasodilator in rat skin and effects are antagonised by CGRP 8–37. In this study, CGRP 8–37 significantly ( P<0.05) inhibited the time-dependent (3–5 h) increase in skin blood flow measured in the anaesthetised rat, after intradermal administration of the inflammatory cytokine interleukin-1β (3 pmol/site), indicating the involvement of CGRP1 receptors. The CGRP-related peptide adrenomedullin (ADM) is also a potent vasodilator in rat skin, with effects antagonised by CGRP 8–37. We show that ADM mRNA expression is increased in rat skin after treatment with IL-1β and that the IL-1β-induced blood flow is blocked by a selective ADM antibody ( P<0.05). Thus ADM is expressed locally in the inflamed cutaneous microvasculature where it can, in addition to, or as an alternative to CGRP, contribute to IL-1β-induced vasoactive effects.