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Updated: Aug 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

Chronic morphine reduces pain-related disability in a rodent model of chronic, inflammatory pain

M D Lindner1, M A Plone, J M Francis

  • 1CytoTherapeutics Incorporated, Lincoln, Rhode Island, USA. mlindner@neurocrine.com

Experimental and Clinical Psychopharmacology
|September 3, 1999
PubMed

Insights

Chronic morphine effectively reduced pain-related disability in rats with arthritis over 35 days. This indicates morphine

Area of Science:

  • Pharmacology
  • Pain Management
  • Animal Models

Background:

  • Chronic pain and morphine's adverse effects cause significant disability.
  • Quantitative measures of functional disability are crucial for assessing treatment efficacy.
  • Morphine's net benefit depends on balancing pain relief against side effects.

Purpose of the Study:

  • To evaluate the efficacy of continuous morphine administration in reducing pain-related functional disability in a rat arthritis model.
  • To assess the relationship between morphine's analgesic effects and its impact on disability.

Main Methods:

  • Adjuvant-induced arthritis was established in rats.
  • Rats received continuous subcutaneous morphine via implanted pellets for 35 days.
  • Pain-related functional disability was measured using tasks motivated by food reward or shock avoidance.

Main Results:

  • Continuous morphine administration significantly reduced pain-related functional disability throughout the 35-day treatment period.
  • Efficacy was observed in both forelimb and hindlimb function tests, reflecting the progression and subsidence of inflammation.
  • Morphine demonstrated a net beneficial effect by alleviating disability despite potential adverse effects.

Conclusions:

  • Continuous morphine is effective in reducing pain-related functional disability in a preclinical model of chronic pain.
  • Quantitative functional measures provide a valuable assessment of chronic pain treatments.
  • Morphine can offer significant functional benefits when its analgesic effects outweigh its adverse effects.

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