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Horm Metab Res 1992; 24(9): 416-419
DOI: 10.1055/s-2007-1003349
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© Georg Thieme Verlag, Stuttgart · New York

Analysis of Nuclear 3,3',5-Triiodothyronine Receptor in the Brown Adipose Tissue (BAT) of the Postnatal Lamb

S. Y. Wu1 , J. K. Kim1 , D. T. Tjioe2 , W. S. Huang3 , I. J. Chopra4
  • 1Nuclear Medicine and Medical Services, Veterans Administration Medical Center, Long Beach, and University of California, Irvine
  • 2Department of Anatomy and Physiology, California State University, Long Beach, U. S. A.
  • 3Department of Nuclear Medicine, Tri-Service General Hospital and National Defense Medical Center, Taipei, Taiwan, ROC
  • 4Department of Medicine, UCLA School of Medicine, Los Angeles, California, USA
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Publication History

1991

1991

Publication Date:
14 March 2008 (online)

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Summary

Postnatal thermogenesis in sheep is associated with increased sympathoadrenal activities, a T3 surge and an enhanced brown adipose tissue (BAT) type II 5'-monodeiodinating (5'-MDI) activity. The latter peaks 3-4 days after birth and is known to be important in generating intracellular T3 for nuclear receptor binding. In order to further investigate the mechanism(s) responsible for neonatal thermogenesis, thyroid hormone nuclear receptor (T3NR) binding characteristics were quantified in lamb BAT from newborn (NB) to 30d of postnatal age. Maximal binding capacities (MBC, mean±SEM fmoles T3/mg DNA) in BAT showed a decrease as studied by ANOVA during the first 11 days (NB to Id, 148±24 [N = 5, p < 0.01, cf.3-5d group];3-5d, 61±5.5[N = 5]; 10-11d, 72±9.1 [N = 4]). Afterwards, MBC increased at 30d (196±32, N = 4, p < 0.01, cf. 3-5d group). BAT T3NR binding affinities (109 M-1 were comparable in all age groups studied (NB-1d, 2.8±0.3; 3-5d, 3.4±0.3; 10-11d, 4.0±1.1; 30d, 2.4±0.4). The data suggest that the postnatal surge in T3 and type II 5'-MDI is accompanied with a concurrent decrease in MBC of BAT T3NR. The latter may represent a down-regulation of T3NR presumably in an attempt to regulate the overall effect of thyroid hormone in neonatal thermogenesis.

Key words

Triiodothyronine (T3) - Nuclear Receptor - Brown Fat - Lambs