Cannabinoid CB1 receptor knockout mice fail to self-administer morphine but not other drugs of abuse

Related Experiment Video

Updated: Oct 9, 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

G Cossu1, C Ledent, L Fattore

  • 1B.B.Brodie Department of Neuroscience, University of Cagliari, Via Porcell 4, 09124, Cagliari, Italy.

Behavioural Brain Research
|February 13, 2001
PubMed

Insights

The CB1 cannabinoid receptor is crucial for morphine

Area of Science:

  • Neuroscience
  • Pharmacology
  • Addiction Research

Background:

  • The CB1 cannabinoid receptor is implicated in modulating the effects of various drugs of abuse.
  • Understanding the specific role of CB1 receptors in drug reward is essential for developing targeted addiction therapies.

Purpose of the Study:

  • To investigate the role of the CB1 cannabinoid receptor in the rewarding effects of morphine, cocaine, amphetamine, and nicotine.
  • To determine if CB1 receptor knockout affects the self-administration of these drugs.

Main Methods:

  • Utilized an intravenous self-administration model in CB1 receptor knockout mice and wild-type littermates.
  • Employed a nose-poking response (NPR)-like operandum in drug-naive animals.

Main Results:

  • Morphine self-administration was abolished in CB1 receptor knockout mice but present in wild-type mice.
  • Cocaine, amphetamine, and nicotine self-administration levels were comparable between CB1 receptor knockout and wild-type mice.
  • These findings highlight the specific involvement of CB1 receptors in morphine reward.

Conclusions:

  • The CB1 cannabinoid receptor is essential for the expression of cannabinoid reinforcing effects.
  • CB1 receptors play a critical role in modulating the rewarding effects of morphine.
  • The CB1 receptor's involvement in drug reward is drug-specific, as demonstrated by the differential effects on morphine versus psychostimulants and nicotine.

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