Dissociation of naloxone-sensitive and naloxone-insensitive effects of U-50,488H.
This study was designed to compare the dose-related effects of U-50,488H on the cortical electroencephalogram (EEG) and behavior, following either saline or naloxone pretreatment. Adult female Sprague-Dawley rats were implanted with chronic cortical EEG and temporalis muscle electromyographic (EMG) recording electrodes and with permanent cannulae in the external jugular vein. U-50,488H injection produced initial "psychotomimetic-like" EEG and behavioral effects for about 10-20 min, followed by a predominance of behavioral stupor and associated EEG slow-wave bursts for about 20 min. Naloxone pretreatment completely antagonized the behavioral stupor and associated EEG slow-wave bursts. However, the "psychotomimetic-like" effects were not antagonized by naloxone pretreatment. Thus, dissociation between naloxone-sensitive and naloxone-insensitive effects of U-50,488H was demonstrated.
Department of Pharmacology and Toxicology, University of Maryland School of Pharmacy, Baltimore 21201.
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Young
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D009270:Naloxone / Q000494:pharmacology*; D011759:Pyrrolidines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012890:Sleep / Q000187:drug effects
D011759:Pyrrolidines; D009270:Naloxone; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer