title: The stimulus properties of morphine and ethanol.
abstract: The present investigation sought (a) to establish the efficacy of morphine and ethanol as discriminative stimuli when each is paired with the administration of saline and (b) to compare, in a qualitative sense, the stimulus properties of the two drugs. Additional experiments examined the effects of treatment with naloxone or l-propranolol upon morphine and ethanol-mediated discriminated responding. Finally, the stereospecificity of the stimuli produced by morphine was determined by a comparison, in morphine-trained rats, of levorphanol and dextrorphan. Discriminated responding developed rapidly in both the morphine and ethanol groups. In tests in which ethanol was administered to morphine-trained animals and vice versa, no similarity to stimulus properties was apparent. Antagonism of discriminated responding induced by morphine and ethanol was attempted using naloxone and l-propranolol. Naloxone blocked the actions of morphine but was without effect upon ethanol. No evidence of antagonism of either drug by propranolol was found. When a range of doses of levorphanol (0.1-3 mg/kg) and dextrorphan (3-100 mg/kg) was tested in morphine trained animals, only levorphanol was able to substitute for morphine. The present results suggest that the stimulus properties of morphine represent typical opiate effects.
mesh_terms: D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects; D003917:Dextrorphan / Q000494:pharmacology; D004192:Discrimination, Psychological / Q000187:drug effects*; D000431:Ethanol / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005260:Female; D007981:Levorphanol / Q000494:pharmacology; D009020:Morphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D004364:Pharmaceutical Preparations; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D012965:Sodium Chloride; D013237:Stereoisomerism; D013268:Stimulation, Chemical; D013329:Structure-Activity Relationship
chemical_list: D004364:Pharmaceutical Preparations; D003917:Dextrorphan; D007981:Levorphanol; D009270:Naloxone; D000431:Ethanol; D012965:Sodium Chloride; D009020:Morphine; D011433:Propranolol