Nociceptin effects in the airways

The opioid-like heptadecapeptide nociceptin (NC) has the following effects in the airways (investigated in isolated tracheae and bronchi from guinea p ig or rat): the electric field stimulation (EFS)-induces release of acetylc holine (ACh), the tachykinin substance P (SP) and calcitonin gene-related p eptide (CGRP) is reduced after pretreatment with NC, and EFS-induced tachyk inergic nonadrenergic-noncholinergic (NANC) bronchoconstriction is inhibite d by NC. Both the NC-mediated inhibition of neurotransmission and of smooth muscle contraction occurred in a concentration-dependent manner. Because t hese effects were naloxone-insensitive, were blocked by the NC receptor ant agonist [F/G]NC(1-13)NH2, and could be mimicked by the NC analogs, NCNH2 an d NC(1-13)NH2, it is thought that they are distinct from the classic opioid receptors. That these pharmacological actions of NC are of relevance for a irway physiology is highly probable given the presence of NC-immunoreactivi ty in the nerve fibers of the airways and of opioid-like receptor (ORL-1) t ranscripts in the jugular ganglia, from where the tachykinin-containing aff erents arise. (C) 2000 Elsevier Science Inc. All rights reserved.