ISSN:
1432-2072
Keywords:
Morphine
;
Associated Discrimination
;
Methadone
;
Loperamide
;
Haloperidol
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract In an operant procedure of lever pressing at FR10 schedule of food reinforcement, rats were trained to respond differentially in order to discriminate the effects of morphine (10 mg/kg) injection from those of saline injection. These rats learned to press a lever on one side after morphine injection and a lever on the opposite side after saline injection. In subsequent testing, these rats reliably emitted responses on the morphine lever after 10 or 20 mg/kg of morphine IP, 50 mg/kg of morphine given orally or 2 mg/kg methadone. Two mg/kg of morphine (or 10 or 20 mg/kg given orally) was recognized as saline. In contrast, after either loperamide (an antidiarrheal drug) given in doses up to 10 mg/kg or haloperidol (a neuroleptic) given in doses up to 0.32 mg/kg, all responses were made on the saline lever. Higher doses suppressed responding. Since neither the antidiarrheal activity nor the neuroleptic activity was sufficient to provide the discriminable cue associated with morphine, it is suggested that specific central effects produced only by narcotic analgesics are the basis for these morphine cues.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00428935
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