Impaired transport of thyroid hormones into livers of obese (ob/ob) mice
- Michigan State Univ., Lansing (USA)
Obese (ob/ob) mice exhibit impaired hepatic thyroid hormone action that is mediated, at least in part, by a reduced nuclear 3,5,3{prime}-triiodothyronine (T{sub 3}) receptor occupancy. The possibility that lowered occupancy in obese mice may be caused by decreased transport of T{sub 3} across the hepatic plasma membrane was examined by measuring the unidirectional influx of ({sup 125}I)T{sub 3} into livers of 8- to 10-wk-old obese and lean mice using a tissue-sampling portal vein-injection technique. Influx of ({sup 125}I)thyroxine (T{sub 4}), a substrate for T{sub 4} 5{prime}-deiodinase, was also measured. Unidirectional clearance of T{sub 3} and T{sub 4} was 64 and 80% lower, respectively, in obese mice than in lean mice. Hepatic T{sub 3} and T{sub 4} uptake was nonsaturable in both lean and obese mice, suggesting that transport occurs by lipid-mediated free diffusion. Clearance of another lipid-soluble hormone, hydrocortisone, was also lower in obese mice than in lean mice. Decreased membrane permeability to the above hormones in obese mice may result from reported changes in membrane lipid composition. In conclusion, decreased hepatic thyroid hormone uptake may contribute to impaired thyroid hormone action and T{sub 3} production in livers of obese mice.
- OSTI ID:
- 7191998
- Journal Information:
- American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 255:1; ISSN 0002-9513; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ADIPOSE TISSUE
ADRENAL HORMONES
AMINO ACIDS
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BLOOD FLOW
BODY
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CLEARANCE
CONNECTIVE TISSUE
CORTICOSTEROIDS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DISEASES
ELECTRON CAPTURE RADIOISOTOPES
GLANDS
GLUCOCORTICOIDS
HORMONES
HYDROCORTISONE
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
KETONES
KINETICS
LABELLED COMPOUNDS
LIVER
MAMMALS
MEMBRANE TRANSPORT
METABOLIC DISEASES
MICE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
PATHOGENESIS
PEPTIDE HORMONES
PERMEABILITY
PREGNANES
RADIOISOTOPES
REACTION KINETICS
RODENTS
STEROIDS
THYROID HORMONES
THYROXINE
TISSUES
TRIIODOTHYRONINE
VERTEBRATES