Document Detail

Glucocorticoid receptor and ubiquitin expression after repeated eccentric exercise.
MedLine Citation:
PMID:  14652497     Owner:  NLM     Status:  MEDLINE    
INTRODUCTION/PURPOSE: Eccentric exercise causes muscle proteolysis that may be attenuated with repeated exercise. Therefore, this study determined the effect of repeated bouts of eccentric exercise on ubiquitin (UBI), ubiquitin conjugating enzyme (E2), and 20S proteasome (20S) and glucocorticoid receptor (GR) mRNA and protein expression, myofibrillar protein content, DNA content, caspase-3 activity, serum skeletal muscle troponin-I (sTnI) and cortisol (CORT), and muscle strength. METHODS: Nine males underwent two identical eccentric exercise bouts (BT1 and BT2) 3 wk apart involving seven sets of 10 repetitions at 150% one-repetition maximum of the dominant knee extensors. Blood and muscle biopsy samples were obtained before and at 6 and 24 h postexercise whereas muscle strength was assessed before and at 24, 48, and 72 h postexercise. Data were analyzed with separate 2 x 3 and 2 x 4 factorial ANOVA (P < 0.05). RESULTS: Decrements in strength and increased soreness occurred at 24 and 48 h postexercise for both bouts (P < 0.05); however, the changes for BT1 were greater than BT2. Serum CORT and sTnI were greater immediately after and at 6, 24, and 48 h postexercise for both bouts; however, the differences in BT1 were greater than BT2 (P < 0.05). Caspase-3 activity and the mRNA and protein levels of UBI, E2, 20S, and GR were increased at 6 and 24 h postexercise, and these differences were greater for BT1 than BT2 (P < 0.05). For BT1, DNA and myofibrillar protein content decreases were apparent at 24 h postexercise (P < 0.05) but not in BT2. CONCLUSION: These results indicate that muscle injury occurring from an initial bout of eccentric exercise seems to decrease muscle strength and myofibrillar protein, possibly due to apoptosis and up-regulation of glucocorticoid receptor mediated increases in UBI-proteolytic pathway activity, all of which appear to be tempered with a repeated eccentric exercise bout.
Darryn S Willoughby; Melanie Taylor; Lemuel Taylor
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  35     ISSN:  0195-9131     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2003 Dec 
Date Detail:
Created Date:  2003-12-03     Completed Date:  2004-04-30     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2023-31     Citation Subset:  IM; S    
Department of Kinesiology, Texas Christian University, Fort-Worth 76129, USA.
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MeSH Terms
Caspase 3
Caspases / metabolism
Cysteine Endopeptidases / metabolism
Exercise / physiology*
Exercise Test
Multienzyme Complexes / metabolism
Muscle Contraction / physiology
Muscle Proteins / metabolism
Muscle, Skeletal / enzymology,  metabolism*,  pathology
Proteasome Endopeptidase Complex
Receptors, Glucocorticoid / metabolism*
Ubiquitin / metabolism*
Ubiquitin-Conjugating Enzymes / metabolism
Reg. No./Substance:
0/Multienzyme Complexes; 0/Muscle Proteins; 0/Receptors, Glucocorticoid; 0/Ubiquitin; EC 3.4.22.-/CASP3 protein, human; EC 3.4.22.-/Caspase 3; EC 3.4.22.-/Caspases; EC 3.4.22.-/Cysteine Endopeptidases; EC Endopeptidase Complex; EC Enzymes

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

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