Pharmacological properties of TRK-820 on cloned mu-, delta- and kappa-opioid receptors and nociceptin receptor.
We analyzed the pharmacological properties of 17-cyclopropylmethyl-3,14beta-dihydroxy-4,5alpha-epoxy-6b eta-[N-methyl-trans-3-(3-furyl)acrylamido]morphinan hydrochloride (TRK-820) using Chinese hamster ovary (CHO) cells expressing cloned rat mu-, delta- and kappa-opioid receptors and human nociceptin receptor. TRK-820 showed high affinity for the kappa-opioid receptor, with a Ki value of 3.5 +/- 0.9 nM. In CHO cells expressing kappa-opioid receptors, TRK-820 inhibited forskolin-stimulated cAMP accumulation, and the maximal inhibitory effect was equivalent to that of (+)-(5alpha,7alpha,8beta)-N-methyl-N-[7-(1-pyrrolidiny l)-1-oxaspiro-(4,5)dec-8-yl]benzeneacetamide (U69,593), a full agonist of kappa-opioid receptor. In CHO cells expressing mu-opioid receptors, TRK-820 inhibited cAMP accumulation, but the maximal inhibitory effect was significantly smaller than that of [D-Ala2, N-MePhe4, Gly-ol5]enkephalin (DAMGO), a full agonist of mu-opioid receptor. In CHO cells expressing delta-opioid receptor, the inhibitory effect of TRK-820 on cAMP accumulation was very weak. Using site-directed mutagenesis, the high affinity of TRK-820 for the kappa-opioid receptor was revealed to require Glu297. TRK-820 bound to the nociceptin receptor with a Ki value of 380 +/- 50 nM. TRK-820 by itself had no effect on cAMP accumulation in CHO cells expressing nociceptin receptors, but significantly antagonized the nociceptin (10 nM)-mediated inhibition of cAMP accumulation at high concentrations. These results indicate that TRK-820 acts as a full agonist for the kappa-opioid receptor, a partial agonist for the mu-opioid receptor and a low-affinity antagonist for the nociceptin receptor.
Seki
T
T
Department of Molecular Pharmacology, Faculty of Pharmaceutical Sciences, Kyoto University, Japan.
Awamura
S
S
Kimura
C
C
Ide
S
S
Sakano
K
K
Minami
M
M
Nagase
H
H
Satoh
M
M
D000818:Animals; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D006801:Humans; D008024:Ligands; D009019:Morphinans / Q000378:metabolism / Q000494:pharmacology*; D009154:Mutation; D009270:Naloxone / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D011957:Receptors, Opioid / Q000819:agonists / Q000187:drug effects* / Q000378:metabolism; D017465:Receptors, Opioid, delta / Q000819:agonists / Q000187:drug effects* / Q000378:metabolism; D017473:Receptors, Opioid, kappa / Q000819:agonists / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000187:drug effects* / Q000378:metabolism; D013141:Spiro Compounds / Q000378:metabolism / Q000494:pharmacology*; D000094942:Nociceptin Receptor
D008024:Ligands; D009019:Morphinans; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D013141:Spiro Compounds; C058380:naloxone benzoylhydrazone; C111212:TRK 820; D009270:Naloxone; D000094942:Nociceptin Receptor