[The discriminative stimulus properties of naloxone during dissociative learning in a Y maze in morphine-dependent rats].
The study was dedicated to evaluation of discriminative stimulus properties of opiate withdrawal syndrome precipitated by naloxon. The possibility of naloxon-appropriate reaction significantly increased in a dose-dependent manner (0-1.0 mg/kg, ED50 = 0.03 mg/kg) and was observed during the period of morphine withdrawal (8-96 h, peak at 24 h). Naloxone stimulus effects were antagonized by morphine (10-100.mg/kg), thus providing the experimental evidence for competitive and saturatable nature of interaction with opiate receptors. The probability of naloxone-appropriate reaction decreased during administration of the conditioned stimulus associated with morphine injection. Ligands of peripheral opiate receptors failed to either substitute for naloxone (methylnaloxon, 0.1-3.0 mg/kg) or attenuate naloxone stimulus effects (loperamide, 1-30 mg/kg).
D000818:Animals; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology; D004193:Discrimination Learning / Q000187:drug effects* / Q000502:physiology; D004213:Dissociative Disorders / Q000139:chemically induced* / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D008297:Male; D018782:Maze Learning / Q000187:drug effects* / Q000502:physiology; D009020:Morphine / Q000009:adverse effects; D009021:Morphine Dependence / Q000503:physiopathology*; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D009294:Narcotics / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar; D013375:Substance Withdrawal Syndrome / Q000209:etiology / Q000503:physiopathology