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The effects of anorexic drugs on free-fed rats responding under a second-order FI15-min (FR10:S) schedule for high incentive foods.
MedLine Citation:
PMID:  17218798     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Many similarities exist between the overconsumption of food, which results in obesity, and drug addiction. The present study investigated the effects of anorectic drugs on responding maintained by high incentive, but nutritionally unnecessary, food reinforcers using an FI15(fixed-ratio 10:S) schedule of reinforcement, similar to that used in studies on the incentive properties of drugs of abuse. Rats were trained to respond on a lever to gain access to two high incentive foods--chocolate chip cookies and cheese. Under the FI15(FR10:S) schedule, every 10th response (fixed-ratio 10) delivered a tone and light conditioned stimulus. The first ratio completed 15 min after the start of the session produced the conditioned stimulus and opened a door to give access to a piece of cookie. After 5 min to consume the high incentive food, a second 15-min interval was started, terminating in access to a second reinforcer, cheese. Once trained, the rats were given free access to laboratory chow in the home cage. They continued to work for the high incentive foods for a period of over 1 year, showing a pattern of responding appropriate to an FI(fixed-ratio) schedule. Naloxone (1.0 mg/kg), fenfluramine (1 and 2 mg/kg), D-amphetamine (0.25 and 0.5 mg/kg), and rimonabant (3 mg/kg) significantly reduced responding, especially in the second interval. In contrast, complete removal of the high incentive food from the test procedure did not immediately reduce the rate of responding, tending to increase it in the second of the intervals. Apparently, the drugs did not reduce responding by reducing the experienced magnitude of the high incentive food, but more probably by reducing the animals' motivation.
Authors:
John Evenden; Tracey Ko
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Behavioural pharmacology     Volume:  18     ISSN:  0955-8810     ISO Abbreviation:  Behav Pharmacol     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-01-12     Completed Date:  2007-05-02     Revised Date:  2009-07-07    
Medline Journal Info:
Nlm Unique ID:  9013016     Medline TA:  Behav Pharmacol     Country:  England    
Other Details:
Languages:  eng     Pagination:  61-9     Citation Subset:  IM    
Affiliation:
Department of Neuroscience Biology, CNS Discovery, AstraZeneca R&D Wilmington, Wilmington, Delaware 19850, USA. john.evenden@astrazeneca.com
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MeSH Terms
Descriptor/Qualifier:
Animals
Appetite / drug effects*
Appetite Depressants / pharmacology*
Appetitive Behavior / drug effects*
Body Weight / drug effects
Dextroamphetamine / pharmacology
Dose-Response Relationship, Drug
Energy Intake / drug effects
Extinction, Psychological / drug effects
Feeding Behavior / drug effects*
Fenfluramine / pharmacology
Male
Motivation*
Naloxone / pharmacology
Piperidines / pharmacology
Pyrazoles / pharmacology
Rats
Rats, Long-Evans
Reinforcement Schedule*
Chemical
Reg. No./Substance:
0/Appetite Depressants; 0/Piperidines; 0/Pyrazoles; 158681-13-1/rimonabant; 458-24-2/Fenfluramine; 465-65-6/Naloxone; 51-64-9/Dextroamphetamine

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


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