Nociceptin, a novel endogenous ligand for the orl1 receptor, has
potent erectile activity in the cat..
Champion, Hunter C., Run Wang, Wayne J. G. Hellstrom, and Philip J.
Kadowitz.
Departments of Pharmacology and Urology, Tulane University School
of Medicine, New Orleans, Louisiana, 70112
APStracts 4:0091E, 1997.
The heptadecapeptide nociceptin, also known as Orphanin FQ, is a newly
discovered endogenous ligand for the opioid-like G-protein coupled
receptor, ORL1. The present study was undertaken to investigate the
effects of intracavernosal injections of nociceptin on penile
erection in anesthetized cats. Responses to nociceptin were compared
to erectile responses elicited by intracavernosal injection of
vasoactive intestinal polypeptide (VIP), adrenomedullin (ADM), the
novel nitric oxide donor DEA/NO, and the control triple drug
combination (papaverine, phentolamine, and prostaglandin E1). The
order of potency was VIP>ADM>Nociceptin>DEA/NO. Intracavernosal
injections of nociceptin in doses of 0.3-30 nmol elicited dose
-related increases in cavernosal pressure and penile length, which
were comparable to that induced by the triple-drug combination which
is used in the treatment of erectile dysfunction. The response to
nociceptin was rapid in onset and the duration of the peak pressure
increase and total response were significantly shorter than the
response to the control triple-drug combination, but longer in
duration than responses to VIP and ADM. Intracavernosal injection of
the triple-drug combination resulted in a greater decrease in mean
systemic arterial blood pressure than did nociceptin. These data
demonstrate that intracavernosal injection of this novel endogenous
ligand for the ORL1 receptor induces a potent, and relatively long
-lasting erectile response in the cat.
Received 10 January 1997; accepted in final form 2 April 1997.
APS Manuscript Number E17-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 13 May 1997