Abstract |
We investigated the pharmacological properties of a newly synthesised delta agonist AR-M1000390, derived from SNC-80 ((+)-4-[(alpha R)-alpha-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethyl- benzamide), in the neuroblastoma cell line SK-N-BE expressing only human delta-opioid receptors. Binding and functional experiments showed a weak affinity (K(i) = 106 +/- 34 nM) correlated with a weak potency (EC(50) = 111 +/- 31 nM) to inhibit the forskolin-stimulated cAMP accumulation. Sustained activation of opioid receptors in the presence of the maximal inhibitory concentration of AR-M1000390 produced a rapid and strong desensitization. In order to examine the contribution of internalization and down-regulation in the desensitization processes, binding and functional experiments were conducted in the presence or in the absence of hypertonic sucrose solution to block clathrin-dependent opioid receptor endocytosis. We observed both the inability of AR-M1000390 to down-regulate opioid receptors and the absence of any effect of sucrose on desensitization. The lack of delta-opioid receptor internalization by AR-M1000390 was further corroborated by confocal microscopy using antibodies directed either against the endogenous delta-opioid receptors or the FLAG-tagged delta-opioid receptors stably expressed in the SK-N-BE cells. These data suggest that uncoupling rather than internalization is responsible for delta-opioid receptors desensitization by AR-M1000390.
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Authors | Nicolas Marie, Gérard Landemore, Claire Debout, Philippe Jauzac, Stéphane Allouche |
Journal | Life sciences
(Life Sci)
Vol. 73
Issue 13
Pg. 1691-704
(Aug 15 2003)
ISSN: 0024-3205 [Print] Netherlands |
PMID | 12875901
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Benzamides
- N,N-diethyl-4-(phenylpiperidin-4-ylidenemethyl)benzamide
- Narcotic Antagonists
- Piperazines
- Piperidines
- Receptors, Opioid, delta
- 4-(alpha-(4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl)-N,N-diethylbenzamide
- Sucrose
- Adenylyl Cyclases
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Topics |
- Adenylyl Cyclases
(metabolism)
- Benzamides
(pharmacology)
- Down-Regulation
- Endocytosis
(drug effects)
- Humans
- Microscopy, Confocal
- Narcotic Antagonists
(pharmacology)
- Neuroblastoma
(metabolism, pathology)
- Piperazines
- Piperidines
(pharmacology)
- Receptors, Opioid, delta
(agonists, immunology, metabolism)
- Signal Transduction
- Sucrose
(pharmacology)
- Tumor Cells, Cultured
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