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Updated: Jul 16, 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

Agmatine blocks morphine-evoked hyperthermia in rats

Scott M Rawls1, Manisha Amin, Jacob Zisk

  • 1Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA. scott.rawls@temple.edu

Brain Research
|March 23, 2007
PubMed

Insights

Agmatine reduces morphine-induced hyperthermia in rats by activating imidazoline receptors. This effect was blocked by idazoxan, suggesting a specific mechanism for agmatine in modulating opioid-induced temperature changes.

Area of Science:

  • Pharmacology
  • Neuroscience
  • Pain Research

Background:

  • Morphine, a potent analgesic, can induce hyperthermia through mu opioid receptor activation.
  • Agmatine, an endogenous neuromodulator, has shown diverse effects on various physiological systems.
  • The interaction between agmatine and opioid-induced hyperthermia is not well understood.

Purpose of the Study:

  • To investigate the effect of agmatine on morphine-evoked hyperthermia in a rat model.
  • To elucidate the receptor mechanisms involved in agmatine's potential modulation of morphine-induced hyperthermia.

Main Methods:

  • Rats were administered morphine (4 mg/kg, s.c.) to induce hyperthermia.
  • Agmatine (10 and 50 mg/kg, i.p.) was administered alone and in combination with morphine.
  • The effects of co-administration with idazoxan (imidazoline/alpha(2)-adrenoeceptor antagonist) and yohimbine (alpha(2)-adrenoeceptor antagonist) were examined.

Main Results:

  • Agmatine alone did not affect body temperature.
  • Co-administration of agmatine significantly decreased morphine-evoked hyperthermia.
  • The hyperthermic effect of morphine was attenuated by agmatine, and this effect was blocked by idazoxan.
  • Yohimbine did not prevent the attenuation of morphine-induced hyperthermia by agmatine.

Conclusions:

  • Agmatine attenuates morphine-induced hyperthermia in rats.
  • The findings suggest that agmatine exerts its effect by activating imidazoline receptors.
  • Agmatine represents a potential therapeutic target for managing opioid-induced side effects.

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