Nociceptin (1-13), amide is a potent ORL1 (OP4) receptor agonist with a pEC50 of 7.9 for mouse vas deferens and a Ki of 0.75 nM for binding to rat forebrain membranes[1][2].
References:
[1]. Varani K, et al. Nociceptin receptor binding in mouse forebrain membranes: thermodynamic characteristics and structure activity relationships. Br J Pharmacol. 1998 Dec;125(7):1485-90.
[2]. Calo' G, et al. Pharmacology of nociceptin and its receptor: a novel therapeutic target. Br J Pharmacol. 2000 Apr;129(7):1261-83.
















