Document Detail

Exercise regulation of triiodothyronine metabolism.
MedLine Citation:
PMID:  3202159     Owner:  NLM     Status:  MEDLINE    
Negative caloric balance reduces triiodothyronine (T3) production in both humans and rodents. The effects of chronic voluntary exercise and various levels of caloric intake and balance on T3 metabolism were studied in adult male C57/BL6 mice to determine if exercise had any direct effects on T3 production in vivo and in vitro. Chronic voluntary exercise was induced by the addition of running wheels to cages for 28 days. Ad libitum-fed exercising mice ingested 20% greater calories (P less than 0.02), maintained body weight, and increased T3 production (53.1 +/- 5.3 vs. 42.3 +/- 3.4 ng.h-1.100 mg body wt-1; P less than 0.01). Exercising animals pair fed to sedentary ad libitum-fed controls decreased their body mass to an equivalent degree as underfed sedentary animals (caloric intake 75% of ad libitum-fed controls) but had increased T3 clearance compared with weight-matched underfed sedentary control (P less than 0.05). Animals that were underfed and exercised decreased their body weight to a greater extent (P less than 0.01) compared with the sedentary underfed group, but T3 production rates were equal. Activity of liver 5'-deiodinase activity was decreased almost 50% (P less than 0.01) during both exercise plus pair feeding and exercise plus caloric restriction but decreased only 28% during caloric restriction alone (P less than 0.01). T3 metabolic clearance and production rates in vivo were correlated to caloric intake (r = 0.73, P less than 0.01), but an interaction between exercise and caloric balance was observed. Chronic voluntary exercise modulates T3 metabolism via several mechanisms. Exercise has an apparent stimulatory effect independent of caloric intake, but also there are regulatory effects dependent on the absolute level of caloric intake and relative caloric balance.(ABSTRACT TRUNCATED AT 250 WORDS)
H L Katzeff; D Bovbjerg; D A Mark
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  255     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1988 Dec 
Date Detail:
Created Date:  1989-01-26     Completed Date:  1989-01-26     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  E824-8     Citation Subset:  IM    
Department of Medicine, North Shore University Hospital, Manhasset, New York 11030.
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MeSH Terms
Body Weight
Diet, Reducing
Mice, Inbred C57BL
Physical Exertion*
Reference Values
Thyroxine / blood
Triiodothyronine / blood,  metabolism*
Grant Support
Reg. No./Substance:
6893-02-3/Triiodothyronine; 7488-70-2/Thyroxine

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