Document Detail

Cocaine self-administration under fixed and progressive ratio schedules of reinforcement: comparison of C57BL/6J, 129X1/SvJ, and 129S6/SvEvTac inbred mice.
MedLine Citation:
PMID:  16369835     Owner:  NLM     Status:  MEDLINE    
RATIONALE: Combining strains to generate mutant mice may obscure conclusions regarding the targeted gene. Specifically, cocaine may have reduced reinforcing effects in 129 substrains compared to the C57BL/6 strain, commonly used for ES cells and breeding, respectively. OBJECTIVES: We tested the hypothesis that reinforcing effects of cocaine differ between the C57BL/6J strain and two substrains of 129, 129X1/SvJ and 129S6/SvEvTac. METHODS: To assess and reduce performance differences, operant responding was established with liquid food as a reinforcer and evaluated under fixed and progressive ratio schedules. Dose-effect functions for intravenous cocaine self-administration were then determined under both schedules. Finally, reinforced and nonreinforced manipulanda were reversed to assess acquisition of self-administration using a previously nonreinforced response. RESULTS: Relative to C57BL/6J mice, 129X1/SvJ mice showed decreased reinforcing effects of low-magnitude food and cocaine reinforcers. Dose-effect functions for cocaine self-administration were comparable between C57BL/6J and 129S6/SvEvTac mice, despite delayed acquisition of operant behaviors and rightward shifts in the food concentration-effect functions in 129S6/SvEvTac mice. A high cocaine dose clearly served as a positive reinforcer in all three strains in a reversal procedure. CONCLUSIONS: Relative to C57BL/6J mice, the reinforcing effects of cocaine were diminished in 129X1/SvJ mice, but only for low cocaine doses, and a similar profile was observed with food reinforcement. 129S6/SvEvTac mice required more extensive operant training than C57BL/6J mice did, but after acquisition, reinforcing effects of cocaine were similar in the two strains. We suggest that comparable phenotypes observed in gene-targeting studies may result from genetic background, whereas more profound or qualitatively different phenotypes may be more confidently attributed to targeted mutations.
Morgane Thomsen; S Barak Caine
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2005-12-21
Journal Detail:
Title:  Psychopharmacology     Volume:  184     ISSN:  0033-3158     ISO Abbreviation:  Psychopharmacology (Berl.)     Publication Date:  2006 Jan 
Date Detail:
Created Date:  2006-01-13     Completed Date:  2006-06-14     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7608025     Medline TA:  Psychopharmacology (Berl)     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  145-54     Citation Subset:  IM    
Alcohol and Drug Abuse Research Center, McLean Hospital-Harvard Medical School, 115 Mill Street, Belmont, MA, 02478, USA.
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MeSH Terms
Behavior, Animal / drug effects
Cocaine-Related Disorders / psychology*
Conditioning, Operant / drug effects*
Infusions, Intravenous
Mice, Inbred C57BL
Mice, Inbred Strains
Reinforcement (Psychology)
Reinforcement Schedule
Self Administration
Species Specificity
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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