Related Experiment Video

Updated: May 5, 2026

Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
07:23

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

Published on: July 29, 2014

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Regulation of opioid receptor trafficking and morphine tolerance by receptor oligomerization

Li He1, Jamie Fong, Mark von Zastrow

  • 1Ernest Gallo Clinic and Research Center, University of California San Francisco, Emeryville, CA 94608, USA.

Cell
|February 8, 2002
PubMed

Insights

Morphine tolerance, a challenge in chronic pain management, can be reduced. Combining morphine with DAMGO facilitates mu opioid receptor (MOR) endocytosis, significantly decreasing analgesic tolerance in rats.

Area of Science:

  • Pharmacology
  • Neuroscience
  • Pain Management

Background:

  • Chronic pain treatment is limited by morphine tolerance.
  • Morphine activates mu opioid receptors (MOR) without promoting desensitization or endocytosis.
  • Developing strategies to overcome analgesic tolerance is crucial for effective pain management.

Purpose of the Study:

  • To investigate if DAMGO can facilitate MOR endocytosis induced by morphine.
  • To determine if co-administration of morphine and DAMGO reduces analgesic tolerance.
  • To explore the potential of MOR endocytosis as a therapeutic target for chronic pain.

Main Methods:

  • Utilized [D-Ala(2)-MePhe(4)-Gly(5)-ol] enkephalin (DAMGO) to target MOR.
  • Administered morphine and DAMGO to rats for chronic treatment.
  • Assessed analgesic tolerance by comparing drug efficacy over time.

Main Results:

  • DAMGO facilitated morphine-induced MOR endocytosis.
  • Rats treated with both morphine and DAMGO exhibited reduced analgesic tolerance compared to morphine-only treatment.
  • MOR endocytosis was shown to mitigate the development of analgesic tolerance.

Conclusions:

  • MOR endocytosis is a viable mechanism to reduce opioid analgesic tolerance.
  • Co-administration of MOR-internalizing agents with morphine offers a potential strategy for improved chronic pain therapy.
  • This research paves the way for developing novel opioid analogs with sustained analgesic efficacy.

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