Modulation of the stimulus effects of morphine by d-amphetamine.
The stimulus effects of morphine and d-amphetamine coadministration were studied in rats. Place conditioning, drug discrimination, and taste conditioning were employed to assess the rewarding, discriminative, and aversive stimulus properties of both drugs. d-Amphetamine increased the rewarding and morphine-like discriminative stimulus effects of 1.25 mg/kg morphine. d-Amphetamine did not, however, change the aversive effects of 1.25 mg/kg morphine, or any effect of higher (5-20 mg/kg) morphine doses. Because the rewarding/discriminative properties and the aversive properties of a drug are considered the main attributes that regulate (facilitate and weaken, respectively) drug-seeking behavior, the present data are in keeping with clinical reports indicating that amphetamines are sometimes used by opiate abusers in an attempt to increase the effect obtained from poor-quality heroin.
Gaiardi
M
M
Department of Pharmacology, University of Bologna, Italy.
Bartoletti
M
M
Gubellini
C
C
Bacchi
A
A
Babbini
M
M
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D003216:Conditioning, Operant / Q000187:drug effects; D003913:Dextroamphetamine / Q000494:pharmacology*; D004193:Discrimination Learning / Q000187:drug effects; D015259:Dopamine Agents / Q000494:pharmacology*; D004347:Drug Interactions; D007858:Learning / Q000187:drug effects*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D013268:Stimulation, Chemical
D000701:Analgesics, Opioid; D015259:Dopamine Agents; D009020:Morphine; D003913:Dextroamphetamine