Long-lasting sensitization of reward-directed behavior by amphetamine

Exposure to psychostimulant drugs of abuse such as amphetamine can result in long-lasting “sensitization” of reward-directed behavior, such that subjects display enhancements in behavior directed by and toward rewards and reward-predictive cues (i.e. “incentive sensitization”). The purpose of these...

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Published in:	Behavioural brain research Vol. 201; no. 1; pp. 74 - 79
Main Authors:	Mendez, Ian A., Williams, Matthew T., Bhavsar, Atasi, Lu, Annie P., Bizon, Jennifer L., Setlow, Barry
Format:	Journal Article
Language:	English
Published:	Shannon Elsevier B.V 19-07-2009 Elsevier
Subjects:	Amphetamine Analysis of Variance Animals Behavioral psychophysiology Biological and medical sciences Central Nervous System Stimulants - administration & dosage Conditioning, Classical - drug effects Dextroamphetamine - administration & dosage Feeding Behavior - drug effects Fundamental and applied biological sciences. Psychology Incentive motivation Instrumental responding Male Medical sciences Motor Activity - drug effects Neuropharmacology Pharmacology. Drug treatments Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease) Psychology. Psychoanalysis. Psychiatry Psychology. Psychophysiology Psychopharmacology Psychostimulant Rats Rats, Long-Evans Reward Sensitization Instrumental responding Sensitization Amphetamine Psychostimulant Incentive motivation Amphetamine derivatives Incentive CNS stimulant Psychotropic Motivation Amfetamine Behavior Reward
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Summary:	Exposure to psychostimulant drugs of abuse such as amphetamine can result in long-lasting “sensitization” of reward-directed behavior, such that subjects display enhancements in behavior directed by and toward rewards and reward-predictive cues (i.e. “incentive sensitization”). The purpose of these experiments was to determine the degree to which such sensitization resulting from chronic amphetamine exposure influences both appetitive and consummatory food-motivated behavior. Adult male Long-Evans rats received daily i.p. injections of d-amphetamine (2.0 mg/kg) or saline vehicle for five consecutive days. This amphetamine exposure regimen produced lasting sensitization to the acute locomotor stimulant effect of the drug. One month after drug exposure rats were tested for instrumental responding (lever pressing) for food reward under various response schedules. Two months after drug exposure, rats were tested for food consumption in a discriminative Pavlovian context-potentiated eating task, involving pairings of one context with food and another context with no food. Amphetamine exposed rats showed significantly greater instrumental responding for food reward than saline controls, particularly under conditions of high response ratios. In the potentiated eating task, testing under conditions of food satiation revealed that amphetamine exposed rats ate significantly more than saline controls in the food-paired context. These experiments demonstrate that amphetamine exposure can cause enduring increases in both appetitive and consummatory aspects of natural reward-directed behavior. Such long-lasting incentive sensitization could account in part for the propensity for relapse in drug addiction, as well as for reported enhancements in non-drug reward-related behavior.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0166-4328 1872-7549
DOI:	10.1016/j.bbr.2009.01.034