Document Detail


Diurnal variations in natural and drug reward, mesolimbic tyrosine hydroxylase, and clock gene expression in the male rat.
MedLine Citation:
PMID:  19926806     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The impact of the circadian timing system upon behavior and physiology is pervasive, and previous evidence suggests a circadian modulation of drug-seeking behavior and responsiveness to drugs of abuse. To further characterize daily rhythms in reward and to extend these observations to natural reinforcers, diurnal variation in the rewarding value of sex and systemic amphetamine was assessed via the conditioned place preference paradigm. To identify potential mechanisms for rhythmicity in reward, levels of tyrosine hydroxylase (TH) and core clock proteins (Period1 and Bmal1) were examined across the day in the ventral tegmental area (VTA) and the nucleus accumbens (NAcc). During an initial training period, male rat sexual performance varied diurnally with a nadir near the light-to-dark transition. Diurnal rhythms also were evident for both mating and amphetamine-related reward. However, the rhythms for these particular stimuli exhibited differences in their pattern of timing, with sex reward showing a peak during the middark period and amphetamine reward exhibiting high points during the late night and midday with a nadir prior to the light-to-dark transition. A diurnal variation also was seen for the locomotor-activating effect of acute amphetamine administration with a peak during the late night. Western blot analyses revealed that Period1 and Bmal1 protein levels were rhythmic in the NAcc but not in the VTA. By contrast, TH protein levels were rhythmic in both the NAcc and VTA, but the peaks differed with that in the NAcc coinciding with the peak of sex reward and that in the VTA associated with the peak in amphetamine reward. Thus, it appears that both natural and drug-related reward vary in a diurnal fashion but differ in the timing of their peak and nadir levels. The phase relationships between reward rhythms and mesolimbic TH protein levels suggest that an increased capacity for the release of dopamine in the NAcc may underlie the rhythms in sex-related reward, while amphetamine-related reward occurs at a time when the likelihood of evoked NAcc DA release is relatively low.
Authors:
Ian C Webb; Ricardo M Baltazar; Xu Wang; Kyle K Pitchers; Lique M Coolen; Michael N Lehman
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of biological rhythms     Volume:  24     ISSN:  1552-4531     ISO Abbreviation:  J. Biol. Rhythms     Publication Date:  2009 Dec 
Date Detail:
Created Date:  2009-11-20     Completed Date:  2010-01-20     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8700115     Medline TA:  J Biol Rhythms     Country:  United States    
Other Details:
Languages:  eng     Pagination:  465-76     Citation Subset:  IM    
Affiliation:
Department of Anatomy and Cell Biology, University of Western Ontario, London, Canada.
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MeSH Terms
Descriptor/Qualifier:
Amphetamine / pharmacology*
Animals
CLOCK Proteins / biosynthesis*
Circadian Rhythm / physiology*
Conditioning, Operant / physiology
Male
Motor Activity / drug effects
Nucleus Accumbens / physiology*
Rats
Rats, Sprague-Dawley
Reward*
Sexual Behavior, Animal / physiology*
Suprachiasmatic Nucleus / metabolism
Tyrosine 3-Monooxygenase / biosynthesis*
Ventral Tegmental Area / physiology*
Chemical
Reg. No./Substance:
300-62-9/Amphetamine; EC 1.14.16.2/Tyrosine 3-Monooxygenase; EC 2.3.1.48/CLOCK Proteins

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


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