title: Decrease of tolerance to, and physical dependence on morphine by, glutamate receptor antagonists.
abstract: The effects of the non-competitive antagonists of the glutamate complex receptor, dizocilpine (MK 801) and ketamine and of the competitive antagonist CGP 39551 were examined on the induction of tolerance to morphine, the development of physical dependence and the expression of the abstinence syndrome to the opiate in mice. Morphine was administered in a single dose (300 mg/kg) of a slow release preparation. Dizocilpine (0.005 or 0.01 mg/kg given at 3, 12 and 24 h after the priming dose of morphine), ketamine (2, 4 or 8 mg/kg, 30 min before and 3, 6, 9 and 24 h after the priming dose) and DL-(E)-2-amino-4-methyl-5-phosphonopentanoate carboxy-ethylester (CGP 39551) (1.5 or 3 mg/kg, but not 6 or 12 mg/kg 30 min before and 12 and 24 h after the priming dose) reduced the intensity of tolerance to, and physical dependence on morphine. The drugs also reduced the intensity of the abstinence behaviour when given in a single dose, 30 min before (s.c.) naloxone (4 mg/kg)-precipitated withdrawal syndrome in mice chronically treated with morphine. Thus, the results of this study indicate that competitive and non-competitive NMDA receptor antagonists prevent morphine tolerance and decrease the development of physical dependence on the opiate in mice.
authors.affiliation: Department of Pharmacology, Faculty of Biological Sciences, University of Concepción, Chile.
authors.forename: P
authors.initials: P
authors.lastname: González
authors.forename: P
authors.initials: P
authors.lastname: Cabello
authors.forename: A
authors.initials: A
authors.lastname: Germany
authors.forename: B
authors.initials: B
authors.lastname: Norris
authors.forename: E
authors.initials: E
authors.lastname: Contreras
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology / Q000627:therapeutic use; D004361:Drug Tolerance; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D007649:Ketamine / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D051379:Mice; D009020:Morphine / Q000009:adverse effects*; D009021:Morphine Dependence / Q000503:physiopathology / Q000517:prevention & control*; D010147:Pain Measurement; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology / Q000517:prevention & control
chemical_list: D018691:Excitatory Amino Acid Antagonists; C064540:CGP 39551; D007649:Ketamine; D016291:Dizocilpine Maleate; D015763:2-Amino-5-phosphonovalerate; D009020:Morphine