Differential binding properties of oripavines at cloned mu- and delta-opioid receptors.
Eur J Pharmacol
; 378(3): 323-30, 1999 Aug 13.
Article
in En
| MEDLINE
| ID: mdl-10493109
ABSTRACT
This study examines the possibility that oripavine opioid receptor agonists bind equally to both high and low affinity states of the mu-opioid receptor. Studies were performed in C6 cells expressing mu- or delta-opioid receptors; high and low agonist affinity states of the receptors were defined by the absence and presence, respectively of Na+ ions and the GTP analog Gpp(NH)p. At the mu-opioid receptor dihydroetorphine and etorphine were full agonists, buprenorphine had moderate efficacy while diprenorphine was an antagonist. At the delta-opioid receptor, dihydroetorphine, etorphine, and diprenorphine had moderate efficacy while buprenorphine was an antagonist. The binding affinities of the oripavines at the mu-opioid receptor decreased only one to 2-fold in the presence of NaCl and Gpp(NH)p. In contrast, decreases in oripavine affinity at the delta-opioid receptor correlated with delta-opioid receptor efficacy. The ability of oripavine agonists to bind with high affinity to the low agonist affinity state of the nu-opioid receptor may explain the high potencies of these compounds in vivo.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Thebaine
/
Receptors, Opioid, delta
/
Receptors, Opioid, mu
Limits:
Animals
Language:
En
Journal:
Eur J Pharmacol
Year:
1999
Document type:
Article
Affiliation country: