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Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
The beta2 adrenergic receptor regulates morphine tolerance and physical dependence
De-Yong Liang1, Xiaoyou Shi, Xiangqi Li
1Veterans Affairs Palo Alto Health Care System, Stanford University, Department of Anesthesiology, 3801 Miranda Ave., Palo Alto, CA 94304, USA.
Behavioural Brain Research
|May 15, 2007
Summary
The beta2 adrenergic receptor (beta2-AR) plays a key role in opioid tolerance and dependence. Blocking beta2-ARs with antagonists may improve long-term opioid pain relief and reduce addiction potential.
Area of Science:
- Neuroscience
- Pharmacology
- Genetics
Background:
- Chronic opioid administration leads to tolerance and dependence, reducing therapeutic efficacy and increasing addiction risk.
- The beta2 adrenergic receptor (beta2-AR) has been implicated in opioid-related responses, but its specific role in tolerance and dependence is unclear.
Purpose of the Study:
- To investigate the role of the beta2-AR in modulating opioid tolerance, physical dependence, and associated gene expression changes.
- To evaluate the potential of beta2-AR antagonists in mitigating these chronic opioid effects.
Main Methods:
- Utilized C57BL/6 and beta2-AR knockout mice to assess morphine dose-response relationships before and after chronic morphine treatment.
- Administered the selective beta2-AR antagonist butoxamine with or after morphine, and assessed physical dependence via naloxone-precipitated withdrawal.
- Measured spinal cord and dorsal root ganglion expression of calcitonin gene-related peptide (CGRP) and substance P (SP) using real-time PCR and ELISA.
Main Results:
- Butoxamine administration reversed morphine tolerance and reduced physical dependence.
- Beta2-AR knockout mice did not develop morphine tolerance.
- Chronic butoxamine with morphine reduced or eliminated the upregulation of CGRP and SP expression.
Conclusions:
- The beta2-AR significantly modulates opioid tolerance and physical dependence.
- Activation of beta2-ARs is necessary for key neurochemical adaptations to chronic opioid use.
- Beta2-AR antagonists show promise for enhancing opioid analgesia and potentially reducing addiction.
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