Antagonistic effect of orphanin FQ on opioid analgesia in rat.

Abstract

AIM:

To study the effect of orphanin FQ (OFQ), a newly discovered heptadecapeptide, on nociception and opioid analgesia.

METHODS:

The intracerebroventricular (i.c.v.) and intrathecal (i.t.h.) injections were used to give the drugs. The tail-flick model of rats were used to test the pain threshold.

RESULTS:

OFQ (i.c.v. or i.t.h.) 0.1 microgram had no effect on nociception but 0.5-10 micrograms induces hyper-reaction of rat to noxious electric stimulus; the decapeptide (OFQ1-10 i.c.v.), a fragment of the OFQ, did not affect the pain reaction of rats. Fentanyl (1 microgram, i.c.v. or i.t.h.), a selective mu-receptor agonist, DSLET (5 micrograms, i.c.v. or i.t.h.), a selective delta-receptor agonist, or U50488H (1 microgram, i.t.h.), a kappa-receptor agonist, induced an increase in pain threshold, when OFQ (0.1 or 1 microgram) was added together with one of them (except for the ith injection of DSLET), the increase of pain threshold was reduced obviously.

CONCLUSION:

OFQ induces hyperalgesia and antagonizes opioid analgesia mediated by mu- and delta-receptors in the brain and by mu- and kappa- but not delta-receptors in the spinal cord of rats.

• Authors: C B Zhu, X L Zhang, S F Xu, X D Cao, G C Wu, M Y Li, D F Cui, Z W Qi
• Journal: Zhongguo yao li xue bao = Acta pharmacologica Sinica (Zhongguo Yao Li Xue Bao) Vol. 19 Issue 1 Pg. 10-4 (Jan 1998) ISSN: 0253-9756 [Print] China
• PMID: 10375749 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Analgesics
• Analgesics, Opioid
• Opioid Peptides
• Receptors, Opioid
• Enkephalin, Leucine
• 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
• enkephalin, Ser(2), Leu(5), Thr(6)-
• nociceptin
• Fentanyl

Topics

• 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer (antagonists & inhibitors)
• Analgesia
• Analgesics (antagonists & inhibitors)
• Analgesics, Opioid (antagonists & inhibitors)
• Animals
• Enkephalin, Leucine (analogs & derivatives, antagonists & inhibitors)
• Fentanyl (antagonists & inhibitors)
• Injections, Intraventricular
• Injections, Spinal
• Male
• Opioid Peptides (pharmacology)
• Pain Threshold (drug effects)
• Rats
• Rats, Sprague-Dawley
• Receptors, Opioid (agonists)