Document Detail

Effect of fatty acids on rat liver nuclear T3-receptor binding.
MedLine Citation:
PMID:  1619999     Owner:  NLM     Status:  MEDLINE    
The effects of selected fatty acids (linoleic, oleic, and palmitic) on triiodothyronine (T3)-receptor binding were compared in isolated rat hepatocytes, rat liver nuclei, and receptor protein. Scatchard analysis indicated that the inhibition of T3-receptor binding by fatty acids was characterized by an increase in Kd and no change in maximum binding capacity (MBC). In isolated receptors, the rank order of potency for inhibition was linoleic acid greater than oleic acid greater than palmitic acid. The Ki for oleic acid in isolated receptors was the same as that for whole nuclei (15.4 +/- 1.3 v 16.3 +/- 1.9 mumol/L, respectively), indicating that the inhibition of nuclear T3 binding is probably at the level of the receptor protein itself. In isolated hepatocytes, linoleic acid was more potent than oleic acid in inhibiting T3 binding to nuclear receptors. Cell-associated T3 was not affected by the presence of fatty acids, implying that cellular uptake of T3 was not inhibited. High concentrations of fatty acids were necessary for inhibition of T3-receptor binding in isolated hepatocytes, with linoleic acid being one to two orders of magnitude less potent in isolated hepatocytes compared with isolated receptors (Ki, 179 +/- 12 v 4.4 +/- 0.5 mumol/L, respectively). It is concluded that the inhibitory effect of fatty acids on T3-receptor binding in isolated rat hepatocytes probably occurs at the level of the nuclear receptor, and does not involve an inhibition of the access of T3 to the receptor. However, in vivo it seems unlikely that fatty acids will have access to the nuclear receptors in sufficiently high concentrations to affect T3-receptor binding in liver cells.
B C Mazzachi; J A Kennedy; M L Wellby; A M Edwards
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Metabolism: clinical and experimental     Volume:  41     ISSN:  0026-0495     ISO Abbreviation:  Metab. Clin. Exp.     Publication Date:  1992 Jul 
Date Detail:
Created Date:  1992-07-31     Completed Date:  1992-07-31     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0375267     Medline TA:  Metabolism     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  788-92     Citation Subset:  IM    
Department of Clinical Chemistry, Queen Elizabeth Hospital, Woodville, South Australia.
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MeSH Terms
Cell Nucleus / metabolism*
Fatty Acids / pharmacology*
Liver / metabolism*
Rats, Inbred Strains
Receptors, Thyroid Hormone / metabolism*
Triiodothyronine / metabolism*
Reg. No./Substance:
0/Fatty Acids; 0/Receptors, Thyroid Hormone; 6893-02-3/Triiodothyronine

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