NTI4F: A non-peptide fluorescent probe selective for functional delta opioid receptors

Tushar Kshirsagar, Albert H. Nakano, Ping Yee Law, Robert Elde, Philip S. Portoghese

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


A non-peptide fluorescent probe, NTI4F, has been developed for the delta (δ) opioid receptor. The probe is a potent δ-antagonist in the mouse vas deferens (MVD) smooth muscle assay and it binds to the δ opioid receptor with high affinity (K(i) = 1 nM) and selectivity. Confocal microscopy indicates that the probe binds to Madin-Darby canine kidney (MDCK) cells transfected with the δ opioid receptor. This binding can be blocked by the δ opioid receptor antagonist, naltrindole (NTI), but not by morphine or ethylketazocine (EK) which are mu (μ)- and kappa (κ)-selective ligands. This fluorescent probe should prove useful in the study of the distribution of the δ opioid receptor.

Original languageEnglish (US)
Pages (from-to)83-86
Number of pages4
JournalNeuroscience Letters
Issue number2-3
StatePublished - Jun 19 1998

Bibliographical note

Funding Information:
We gratefully acknowledge the financial support of the National Institute on Drug Abuse. The authors would also like to thank Mike Powers and Veronika Phillips for technical assistance.


  • Delta opioid receptor
  • Fluorescent probe
  • Naltrindole


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