title: Attenuation of precipitated morphine withdrawal symptoms by acute i.c.v. administration of a group II mGluR agonist.
abstract: 1. We previously showed that chronic i.c.v. antagonism of metabotropic glutamate receptors (mGluRs) concurrently with s.c. morphine significantly attenuated precipitated withdrawal symptoms. Conversely, acute i.c.v. injection of a selective group II mGluR antagonist just before the precipitation of withdrawal exacerbated abstinence symptoms. 2. In the present study, we showed that acute i.c.v. administration of the non-selective mGluR agonist 1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD), as well as the group II selective agonist (2S,1'R,2'R,3'R)-2-(2'.3'-dicarboxycyclopropyl)glycine (DCG-IV), significantly attenuated the severity of precipitated withdrawal symptoms. 3. From these results we hypothesize that chronic opioid treatment may indirectly induce a desensitization of group II mGluRs, which contributes to the development of dependence.
authors.affiliation: Pain Mechanisms Laboratory, Clinical Research Institute of Montreal, Canada.
authors.forename: M E
authors.initials: ME
authors.lastname: Fundytus
authors.forename: T J
authors.initials: TJ
authors.lastname: Coderre
mesh_terms: D000818:Animals; D018690:Excitatory Amino Acid Agonists / Q000008:administration & dosage*; D007276:Injections, Intraventricular; D008297:Male; D009020:Morphine / Q000009:adverse effects*; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D013375:Substance Withdrawal Syndrome / Q000188:drug therapy*
chemical_list: D018690:Excitatory Amino Acid Agonists; D016194:Receptors, N-Methyl-D-Aspartate; D009020:Morphine