Antitussive action of nociceptin in the cat

Experiments were conducted to determine the influence of the specific ORL1 receptor agonist, nociceptin, on the cough reflex in the cat. Cats were ane sthetized and allowed to breathe spontaneously. Cough was elicited by mecha nical stimulation of the intrathoracic airway. Intravenous administration o f nociceptin (0.001-3.0 mg kg(-1)) inhibited cough number and the magnitude of abdominal muscle electromyogram (EMG) discharge during cough in a dose- dependent manner. Nociceptin had no effect on the magnitude of the inspirat ory muscle EMG during cough. These effects of nociceptin were antagonized-b y pretreatment with the ORL1 receptor antagonist, 1-[(3R,4R)-1-cyclooctylme thyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1, 3-dihydro-2H-benzimidazol-2-on e (J-113397, 0.1 mg kg(-1), i.v.). We conclude that intravenous nociceptin inhibits cough in the cat. (C) 2001 Elsevier Science B.V. All rights reserv ed.