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Updated: Aug 21, 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

Opioid tolerance and neuroplasticity

Jianren Mao1

  • 1Pain Research Group, MGH Pain Center, Department of Anesthesia and Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.

Novartis Foundation Symposium
|October 8, 2004
PubMed

Insights

Opioid tolerance and opioid-induced pain sensitivity are cellular adaptations that reduce pain relief effectiveness. Understanding these mechanisms may improve opioid analgesic use.

Area of Science:

  • Neuroscience
  • Pharmacology
  • Pain Management

Background:

  • Opioid analgesics are crucial for managing acute and chronic pain.
  • Opioid analgesic tolerance, a form of cellular adaptation, can diminish treatment efficacy.
  • Neural plasticity mechanisms are increasingly implicated in opioid tolerance development.

Purpose of the Study:

  • To explore the link between neural plasticity and opioid tolerance.
  • To investigate how opioid exposure induces both tolerance and heightened pain sensitivity.
  • To identify potential strategies for enhancing clinical opioid efficacy.

Main Methods:

  • Review of current scientific literature on opioid tolerance and neural plasticity.
  • Analysis of studies investigating N-methyl-D-aspartate receptors, protein kinase C, and glutamate transporters in opioid tolerance.
  • Examination of research on pronociceptive mechanisms in the central nervous system related to opioid use.

Main Results:

  • Opioid tolerance involves cellular adaptations, potentially mediated by neural plasticity.
  • Neural plasticity can activate pronociceptive pathways, counteracting opioid analgesia.
  • Opioid exposure can lead to both tolerance and opioid-induced pain sensitivity, reducing overall effectiveness.

Conclusions:

  • Neural plasticity plays a dual role in opioid effects, contributing to both tolerance and increased pain sensitivity.
  • These converging cellular adaptations significantly impair opioid analgesic efficacy.
  • Further research into these mechanisms offers new avenues for optimizing opioid therapy.

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