Related Experiment Video

Updated: Jun 3, 2025

Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
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Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities

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An opioid efficacy switch for reversible optical control of peripheral analgesia

Luca Posa, Giovanna Romano, Xiang Ji

    Biorxiv : the Preprint Server for Biology
    |January 7, 2025
    PubMed

    Insights

    Researchers developed azo-morphine-3 (AM-3), a light-activated drug targeting mu-opioid receptors (MORs). This innovation allows precise optical control over pain relief, minimizing side effects and overdose risks associated with traditional opioids.

    Area of Science:

    • Pharmacology
    • Neuroscience
    • Structural Biology

    Background:

    • Mu-opioid receptor (MOR) agonists are key analgesics but cause dose-limiting side effects and addiction.
    • Systemic opioid administration complicates understanding of action mechanisms and isolating therapeutic effects.
    • Developing targeted MOR modulators is crucial for safer pain management.

    Purpose of the Study:

    • To design and synthesize a photoswitchable morphinan agonist (AM-3) for optical control of MOR signaling.
    • To investigate the structural basis of agonist efficacy using cryo-electron microscopy (cryo-EM).
    • To evaluate the therapeutic potential and side effect profile of AM-3 in vivo.

    Main Methods:

    • Design, synthesis, and characterization of the photoswitchable agonist azo-morphine-3 (AM-3).
    • Cryo-EM structural determination of AM-3 bound to the MOR in distinct low and high efficacy states.
    • In vivo assessment of AM-3's anti-nociceptive effects and side effect profile in mice.

    Main Results:

    • AM-3 exhibits reversible, light-dependent switching between low and high efficacy states.
    • Distinct binding modes of AM-3 in its trans and cis conformations were elucidated via cryo-EM.
    • AM-3 demonstrated controllable anti-nociception in mice with reduced peripheral side effects.

    Conclusions:

    • Azo-morphine-3 provides a novel tool for optical control of MOR signaling, enabling precise pain management.
    • Structural insights reveal the molecular mechanisms underlying light-controlled agonist efficacy.
    • AM-3 offers a promising strategy for developing safer analgesics with a reduced risk of adverse effects.

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