Orphanin FQ, but not dynorphin A, accelerates colonic transit in rats

Opioid and opioid-like receptors are activated by a variety of endogenous peptides including [Met]enkephalin (met), [Leu]enkephalin (leu), β-endorphin (β-end), α-neodynorphin, dynorphin A (dynA), dynorphin B (dynB), big dynorphin (Big dyn), nociceptin/orphanin FQ (N/OFQ); endomorphin-1 and endomorphin-2 are also potential endogenous peptides. The Greek letter nomenclature for the opioid receptors, μ, δ and κ, is well established, and NC-IUPHAR considers this nomenclature appropriate, along with the symbols spelled out (mu, delta, and kappa), and the acronyms, MOP, DOP, and KOP. [121, 100, 91]. The human N/OFQ receptor, NOP, is considered 'opioid-related' rather than opioid because, while it exhibits a high degree of structural homology with the conventional opioid receptors [294], it displays a distinct pharmacology. Currently there are numerous clinically used drugs, such as morphine and many other opioid analgesics, as well as antagonists such as naloxone, however only for the μ receptor.

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Opioid receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

IUPHAR/BPS Guide to Pharmacology CITE ◽

10.2218/gtopdb/f50/2019.4 ◽

2019 ◽

Vol 2019 (4) ◽

Cited By ~ 2

Author(s):

Anna Borsodi ◽

Michael Bruchas ◽

Girolamo Caló ◽

Charles Chavkin ◽

MacDonald J. Christie ◽

...

Keyword(s):

Opioid Receptors ◽

Opioid Analgesics ◽

Structural Homology ◽

Orphanin Fq ◽

Dynorphin A ◽

Greek Letter ◽

Endogenous Peptides ◽

High Degree ◽

Μ Receptor

Opioid and opioid-like receptors are activated by a variety of endogenous peptides including [Met]enkephalin (met), [Leu]enkephalin (leu), β-endorphin (β-end), α-neodynorphin, dynorphin A (dynA), dynorphin B (dynB), big dynorphin (Big dyn), nociceptin/orphanin FQ (N/OFQ); endomorphin-1 and endomorphin-2 are also potential endogenous peptides. The Greek letter nomenclature for the opioid receptors, μ, δ and κ, is well established, and NC-IUPHAR considers this nomenclature appropriate, along with the symbols spelled out (mu, delta, and kappa), and the acronyms, MOP, DOP, and KOP. [116, 96, 88]. The human N/OFQ receptor, NOP, is considered 'opioid-related' rather than opioid because, while it exhibits a high degree of structural homology with the conventional opioid receptors [282], it displays a distinct pharmacology. Currently there are numerous clinically used drugs, such as morphine and many other opioid analgesics, as well as antagonists such as naloxone, however only for the μ receptor.

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Peripheral and central actions of orphanin FQ (nociceptin) on murine colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1999.276.1.g125 ◽

1999 ◽

Vol 276 (1) ◽

pp. G125-G131 ◽

Cited By ~ 11

Author(s):

M. A. Osinski ◽

P. Bass ◽

E. A. Gaumnitz

Keyword(s):

Contractile Activity ◽

Gastrointestinal Transit ◽

Colonic Transit ◽

Peptide Ligand ◽

Orphanin Fq ◽

Endogenous Opioid ◽

Intracerebroventricular Injections ◽

Central Actions ◽

Murine Colon

Orphanin FQ (OFQ), also known as nociceptin, is a recently isolated endogenous peptide with a structure similar to the endogenous opioid peptides. The present study examines the actions of centrally administered OFQ on in vivo murine gastrointestinal and colonic transit as well as the actions of OFQ on the isolated colon. Intracerebroventricular injections of OFQ dose dependently inhibited colonic propulsive activity. OFQ inhibition of colonic propulsion was unaffected by coadministration of the competitive opioid receptor antagonist naltrexone. A subadditive response was observed when approximately equipotent doses of either morphine sulfate or the δ-agonist DPDPE were coadministered with OFQ. No subadditivity was observed with coadministration of the μ-agonist DAMGO, suggesting a functional interaction between OFQ and δ-opioid central pathways regulating colonic transit. High, but not low, doses of OFQ also inhibited the transit of a nonabsorbable charcoal marker through the stomach and/or small intestine. OFQ potently contracted isolated colon preparations; contractile activity was abolished by TTX or chlorpromazine. Our results suggest that OFQ may be an important peptide ligand acting on a novel inhibitory neural pathway that modulates gastrointestinal transit.

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