The effects of RB101, a mixed inhibitor of enkephalin-catabolizing enzymes, on carrageenin-induced spinal c-Fos expression are completely blocked by beta-funaltrexamine, a selective mu-opioid receptor antagonist.
We have demonstrated that pre-administered RB101 (40 mg/kg, i.v.), a mixed inhibitor of enkephalin-catabolizing enzymes, decreased spinal c-Fos expression induced 1 h and 30 min after intraplantar (i.pl.) carrageenin (41% reduction, p<0.01). These effects were completely blocked by pre-administered beta-funaltrexamine (10 mg/kg, i.v., 24 h prior to stimulation), a selective long-lasting mu-opioid receptor antagonist. In conclusion, these results clearly demonstrate that the effects of endogenous enkephalins on noxiously evoked spinal c-Fos expression are essentially mediated via mu-opioid receptors.
Physiopharmacologie du Système Nerveux, Institut National de la Santé et de la Recherche Médicale U161 and Ecole Pratique des Hautes Etudes, 2 rue d'Alésia, Paris 75014, France. leguen@broca.inserm.fr
S
S
Le Guen
P
P
Honoré
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G
Catheline
M C
MC
Fournié-Zaluski
B P
BP
Roques
J M
JM
Besson
D000818:Animals; D002351:Carrageenan / Q000494:pharmacology*; D004220:Disulfides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008297:Male; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology*; D015260:Neprilysin / Q000037:antagonists & inhibitors; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors*; D013116:Spinal Cord / Q000378:metabolism*
D004220:Disulfides; D004791:Enzyme Inhibitors; D009292:Narcotic Antagonists; D016760:Proto-Oncogene Proteins c-fos; D017450:Receptors, Opioid, mu; C074024:RB 101; D010649:Phenylalanine; D009271:Naltrexone; C024524:beta-funaltrexamine; D002351:Carrageenan; D015260:Neprilysin