Effects of amphetamine, butorphanol, and morphine pretreatment on the maintenance and reinstatement of cocaine-reinforced responding

Wendy J. Lynch, Wayne A. Heaser, Marilyn E Carroll

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Three groups of rats (N = 23) self-administered intravenous cocaine (0.4 mg/kg/infusion) during the initial 2 hr of daily 7-hr sessions. During the remaining 5 hr of these sessions, responding produced saline infusions. On test days, each rat was pretreated with an assigned dose of either butorphanol, morphine, amphetamine, or saline before the self-administration session followed by a printing injection of cocaine (3.2 mg/kg iv) or saline at the beginning of the 4th hr. Results showed that both amphetamine (0.5, 1.0, and 2.0 mg/kg) and morphine (0.3, 1.0, and 2.0 mg/kg) pretreatment dose-dependently reduced cocaine self-administration whereas only amphetamine affected (increased) reinstatement responding. Butorphanol pretreatment (8 mg/kg) suppressed cocaine self-administration and blocked the effect of the cocaine priming injections on pretreatment testing days. These findings indicate that (a) pretreatment drugs with similar stimulus properties potentiate reinstatement of responding and (b) pretreatment drugs can differentially affect maintenance and reinstatement of responding.

Original languageEnglish (US)
Pages (from-to)255-263
Number of pages9
JournalExperimental and Clinical Psychopharmacology
Volume6
Issue number3
DOIs
StatePublished - Aug 1998

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