The Selective mGlu2/3 Receptor Agonist LY354740 Attenuates Morphine-Withdrawal-Induced Activation of Locus Coeruleus Neurons and Behavioral Signs of Morphine Withdrawal

Neuropharmacology. 1999 Feb;38(2):217-22. doi: 10.1016/s0028-3908(98)00196-8.


Naltrexone-precipitated morphine withdrawal induces hyperactivity of locus coeruleus (LC) neurons, as well as a plethora of behavioral withdrawal signs. Previous research has demonstrated that an increased release of glutamate and activation of AMPA receptors, particularly in the LC, play an important role in opiate withdrawal. LY354740 is a novel Group II metabotropic glutamate mGlu2/3 receptor agonist that decreases the release of glutamate. Therefore, we investigated the effect of LY354740 on naltrexone-precipitated morphine-withdrawal-induced activation of LC neurons and behavioral signs of morphine withdrawal. In in vivo recordings from anesthetized rats, pretreatment with LY354740 (3-30 mg/kg, s.c.) dose-dependently attenuated the morphine-withdrawal-induced activation of LC neurons. In unanesthetized, morphine-dependent animals, pretreatment with LY354740 (3-30 mg/kg, s.c.) dose-dependently suppressed the severity and occurrence of many naltrexone-precipitated morphine-withdrawal signs. These results indicate mGlu2/3 receptor agonists: (1) can attenuate the morphine-withdrawal-induced activation of LC neurons and many behavioral signs of morphine withdrawal; and (2) may have therapeutic effects in man for the treatment of opiate withdrawal.

MeSH terms

  • Analysis of Variance
  • Animals
  • Anti-Anxiety Agents / pharmacology
  • Bridged Bicyclo Compounds / pharmacology*
  • Electrophysiology / methods
  • Excitatory Amino Acid Agonists / pharmacology*
  • Locus Coeruleus / physiology
  • Locus Coeruleus / physiopathology*
  • Male
  • Membrane Potentials / drug effects
  • Morphine / toxicity*
  • Morphine Dependence / physiopathology*
  • Naltrexone / pharmacology
  • Neurons / drug effects
  • Neurons / physiology*
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Metabotropic Glutamate / agonists*
  • Substance Withdrawal Syndrome / physiopathology
  • Substance Withdrawal Syndrome / prevention & control*
  • Substance Withdrawal Syndrome / psychology


  • Anti-Anxiety Agents
  • Bridged Bicyclo Compounds
  • Excitatory Amino Acid Agonists
  • Receptors, Metabotropic Glutamate
  • metabotropic glutamate receptor 2
  • metabotropic glutamate receptor 3
  • Naltrexone
  • Morphine
  • eglumetad