Caged naloxone reveals opioid signaling deactivation kineticss

Matthew R. Banghart, John Williams, Ruchir C. Shah, Luke D. Lavis, Bernardo L. Sabatini

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The spatiotemporal dynamics of opioid signaling in the brain remain poorly defined. Photoactivatable opioid ligands provide a means to quantitatively measure these dynamics and their underlying mechanisms in brain tissue. Although activation kinetics can be assessed using caged agonists, deactivation kinetics are obscured by slow clearance of agonist in tissue. To reveal deactivation kinetics of opioid signaling we developed a caged competitive antagonist that can be quickly photoreleased in sufficient concentrations to render agonist dissociation effectively irreversible. Carboxynitroveratrylnaloxone (CNV-NLX), a caged analog of the competitive opioid antagonist NLX, was readily synthesized from commercially available NLX in good yield and found to be devoid of antagonist activity at heterologously expressed opioid receptors. Photolysis in slices of rat locus coeruleus produced a rapid inhibition of the ionic currents evoked by multiple agonists of the μ-opioid receptor (MOR), but not of α-adrenergic receptors, which activate the same pool of ion channels. Using the high-affinity peptide agonist dermorphin, we established conditions under which light-driven deactivation rates are independent of agonist concentration and thus intrinsic to the agonist-receptor complex. Under these conditions, some MOR agonists yielded deactivation rates that are limited by G protein signaling, whereas others appeared limited by agonist dissociation. Therefore, the choice of agonist determines which feature of receptor signaling is unmasked by CNV-NLX photolysis.

Original languageEnglish (US)
Pages (from-to)687-695
Number of pages9
JournalMolecular Pharmacology
Volume84
Issue number5
DOIs
StatePublished - Nov 2013

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Opioid Receptors
Naloxone
Opioid Analgesics
Photolysis
Locus Coeruleus
Narcotic Antagonists
Brain
Ion Channels
GTP-Binding Proteins
Adrenergic Receptors
Ligands
Light
Peptides

ASJC Scopus subject areas

  • Pharmacology
  • Molecular Medicine

Cite this

Caged naloxone reveals opioid signaling deactivation kineticss. / Banghart, Matthew R.; Williams, John; Shah, Ruchir C.; Lavis, Luke D.; Sabatini, Bernardo L.

In: Molecular Pharmacology, Vol. 84, No. 5, 11.2013, p. 687-695.

Research output: Contribution to journalArticle

Banghart, MR, Williams, J, Shah, RC, Lavis, LD & Sabatini, BL 2013, 'Caged naloxone reveals opioid signaling deactivation kineticss', Molecular Pharmacology, vol. 84, no. 5, pp. 687-695. https://doi.org/10.1124/mol.113.088096
Banghart, Matthew R. ; Williams, John ; Shah, Ruchir C. ; Lavis, Luke D. ; Sabatini, Bernardo L. / Caged naloxone reveals opioid signaling deactivation kineticss. In: Molecular Pharmacology. 2013 ; Vol. 84, No. 5. pp. 687-695.
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