Document Detail

Circadian regulation of locomotor activity and skeletal muscle gene expression in the horse.
MedLine Citation:
PMID:  20847133     Owner:  NLM     Status:  MEDLINE    
Circadian rhythms are innate 24-h cycles in behavioral and biochemical processes that permit physiological anticipation of daily environmental changes. Elucidating the relationship between activity rhythms and circadian patterns of gene expression may contribute to improved human and equine athletic performance. Six healthy, untrained mares were studied to determine whether locomotor activity behavior and skeletal muscle gene expression reflect endogenous circadian regulation. Activity was recorded for three consecutive 48-h periods: as a group at pasture (P), and individually stabled under a light-dark (LD) cycle and in constant darkness (DD). Halter-mounted Actiwatch-L data-loggers recorded light exposure and motor activity. Analysis of mean activity (average counts/min, activity bouts/day, average bout length) and cosinor parameters (acrophase, amplitude, mesor, goodness of fit) revealed a predominantly ultradian (8.9 ± 0.7 bouts/24 h) and weakly circadian pattern of activity in all three conditions (P, LD, DD). A more robust circadian pattern was observed during LD and DD. Muscle biopsies were obtained from the middle gluteal muscles every 4 h for 24 h under DD. One-way qRT-PCR results confirmed the circadian expression (P < 0.05) of six core clock genes (Arntl, Per1, Per2, Nr1d1, Nr1d2, Dbp) and the muscle-specific transcript, Myf6. Additional genes, Ucp3, Nrip1, and Vegfa, demonstrated P values approaching significance. These findings demonstrate circadian regulation of muscle function and imply that human management regimes may strengthen, or unmask, equine circadian behavioral outputs. As exercise synchronizes circadian rhythms, our findings provide a basis for future work determining peak times for training and competing horses, to reduce injury and to achieve optimal performance.
Ann-Marie Martin; Jeffrey A Elliott; Pat Duffy; Catriona M Blake; Sarra Ben Attia; Lisa M Katz; John A Browne; Vivian Gath; Beatrice A McGivney; Emmeline W Hill; Barbara A Murphy
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-09-16
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  109     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-11-09     Completed Date:  2011-02-18     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1328-36     Citation Subset:  IM    
School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin, Ireland.
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MeSH Terms
Actigraphy / instrumentation
Activity Cycles
Behavior, Animal*
CLOCK Proteins / genetics*
Circadian Rhythm* / genetics
Gene Expression Regulation
Horses / genetics,  physiology*
Housing, Animal
Motor Activity* / genetics
Muscle, Skeletal / metabolism,  physiology*
Reverse Transcriptase Polymerase Chain Reaction
Reg. No./Substance:
EC Proteins

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

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