Chloroxymorphamine, an Opioid Receptor Site-Directed Alkylating Agent Having Narcotic Agonist Activity

Caruso, Thomas P.; Takemori, A. E.; Larson, D. L.; Portoghese, Philip S.

doi:10.1126/science.86208

Cited by 50 publications

(12 citation statements)

References 5 publications

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“…This result is consistent with the observed factor of 3 reduction of potency in the tolerant strips. (3,16,22). /-CNA is an opioid receptor-specific ligand demonstrated to have no effect on a wide range of other receptors (21,22).…”

Section: Resultsmentioning

confidence: 99%

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Opioid receptor reserve in normal and morphine-tolerant guinea pig ileum myenteric plexus.

Chavkin¹,

Goldstein²

1984

Proc. Natl. Acad. Sci. U.S.A.

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We have measured the opioid receptor reserve in the guinea pig ileum myenteric plexus by means of the site-directed alkylating agent, 8-chlornaltrexamine. Treatment of the tissue with low (<10 nM) concentrations of /3-chlornaltrexamine caused a parallel shift of the log concentration-response curves for both normorphine and dynorphin A-(1-13). Analysis of the resulting curves indicated that the Kd values were 1.5 ± 0.5 x 10-6 and 10 ± 4 x 10-9, respectively.Using the naloxone Ke to distinguish between the ,u and K receptors in this tissue, we found that the receptor selectivities of normorphine and dynorphin A-(1-13) were unchanged after a maximum parallel shift, thus demonstrating that there are both spare IL and spare K receptors present. The spare-receptor fraction for both receptor types was about 90%. In morphine-tolerant preparations (chronic pellet implantation), there was an apparent reduction in the fraction of spare IL receptors without any change in the apparent affinity of normorphine. Reduction in the spare receptor fraction does not necessarily imply reduction in the number of binding sites. We suggest that this reduction in receptor reserve is the basis of opioid tolerance, since the agonist concentration needed to produce a given effect is expected to increase as the receptor reserve decreases.The irreversible opioid receptor antagonist, 3-chlornaltrexamine (f-CNA) is a site-directed alkylating agent synthesized and characterized by Portoghese and coworkers (1, 2). We showed previously (3) that in vitro treatment of the myenteric plexus-longitudinal muscle preparation from guinea pig ileum with low concentrations of 3-CNA results in a parallel shift to the right of the log concentration-response curves for [Leulenkephalin, normorphine, and dynorphin A-(1-13). Higher concentrations of f3CNA result in a reduced maximum response with concomitant decrease in slope. These findings provide classical evidence that there are spare opioid receptors (4, 5) in the myenteric plexus.With spare receptors present, the EC50 in the pharmacologic preparation should be lower than the Kd measured by radioreceptor binding techniques. Yet when Creese and Snyder (6) and later Cox et al. (7) [Leulenkephalin, which previously had acted on the 8 receptor, now exerted its full effect (with potency reduced by a factor of 100) through the As receptor, as indicated by a change in its naloxone sensitivity (see below). The first goal of the present study was therefore to determine what types of spare receptors are present in the guinea-pig myenteric plexus.Our initial demonstration of the presence of spare opioid receptors in an intact tissue preparation (3) had two important implications. The first was that the sensitivity of a neuron to an opioid could be controlled by the magnitude of the opioid receptor reserve. This follows from the classical work on spare receptors by Stephenson (4), Ariens et al. (5), and Furchgott (9) showing that the greater the excess of functional receptors present, the lower the concentra...

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Section: Resultsmentioning

confidence: 99%

“…/-CNA is an opioid receptor-specific ligand demonstrated to have no effect on a wide range of other receptors (21,22). Furthermore, the effects of -CNA are not mimicked by nonopioid nitrogen mustard alkylating agents at similar concentrations (2,22).…”

Section: Resultsmentioning

confidence: 99%

Opioid receptor reserve in normal and morphine-tolerant guinea pig ileum myenteric plexus.

Chavkin¹,

Goldstein²

1984

Proc. Natl. Acad. Sci. U.S.A.

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“…The nitrogen mustard derivative of oxymorphone, l3-chloroxymorphamine (�-COA) ( Figure 10) has been shown to be an irreversible agonist in the GPI (61,62). This observation suggests that receptor occupation rather than rate of ligand-receptor dissociation (41) is important for agonist activity in the GPI (40).…”

Section: Agonistsmentioning

confidence: 99%

Affinity Labels for Opioid Receptors

Takemori

Portoghese

1985

Annu. Rev. Pharmacol. Toxicol.

103

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“…This has the advantage of being able to identify the actual amino acids involved with the site. A number of opiate affinity labels have been developed over the years (Portoghese et al, 1978;Caruso et al, 1979;Portoghese et al, 1979;Takemori et al, 1981;Bidlack et al, 1982Bidlack et al, , 1990Bidlack et al, , 1991Sayre et al, 1983;James and Goldstein, 1984;Takemori and Portoghese, 1985;Benyhe et al, 1987;Herblin et al, 1987;Simon et al, 1987Simon et al, , 1993Szatmári et al, 1999a,b). However, covently labeling the site with a radioligand which provides high ratios of specific to nonspecific binding is more difficult.…”

Section: Introductionmentioning

confidence: 97%

Affinity Labeling Mu Opioid Receptors With Novel Radioligands

2005

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1. A series of novel opiate ligands based upon 6alpha-naloxamine have been examined in opioid receptor binding assays. 2. Coupling an ethylamine spacer alone to 6-alpha-naloxamine gave a compound with relatively poor affinity for mu opioid receptors compared to naloxone, although it retained high affinity for kappa1 opioid receptors. Coupling a benzoyl group significantly increased the affinity. The presence at the 4-position of the benzoyl moiety of an amino-(NalAmiBen) or an azido-substituent (NalAziBen) did not significantly effect the affinity at mu receptors. However, iodinating the benzoyl moiety at the 3-position increased the affinity of the derivatives. 3. Two compounds were radiolabeled and evaluated in receptor binding assays. Both radioligands labeled sites in CHO cells stably transfected with the mouse MOR-1 clone. The amino coupound [125I]NalAmiBen and the azido derivative [125I]NalAziBen reversibly bound to membranes from CHO cells transfected with MOR-1 with high affinity in the dark. Exposure of [125I]NalAmiBen to UV did not alter the reversibility of binding, but exposure of [125I]NalAziBen to UV light led to the covalent coupling of the radioligand to the receptor. When run on SDS-PAGE, [125I]NalAziBen binding showed a band at approximately 70-80 kDa. A control corresponding to nonspecific binding failed to reveal any labeling. No bands were observed from membranes labeled with [125I]NalAmiBen.

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Chloroxymorphamine, an Opioid Receptor Site-Directed Alkylating Agent Having Narcotic Agonist Activity

Cited by 50 publications

References 5 publications

Opioid receptor reserve in normal and morphine-tolerant guinea pig ileum myenteric plexus.

Opioid receptor reserve in normal and morphine-tolerant guinea pig ileum myenteric plexus.

Affinity Labels for Opioid Receptors

Affinity Labeling Mu Opioid Receptors With Novel Radioligands

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