Thyroid hormone--sympathetic interaction and adaptive thermogenesis are thyroid hormone receptor isoform--specific
| Autor: | M O, Ribeiro, S D, Carvalho, J J, Schultz, G, Chiellini, T S, Scanlan, A C, Bianco, G A, Brent |
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| Rok vydání: | 2001 |
| Předmět: |
Male
Thyroid Hormones Sympathetic Nervous System Glycerolphosphate Dehydrogenase Acetates Ion Channels Mitochondrial Proteins Mice Norepinephrine Adipose Tissue Brown Hypothyroidism Phenols Heart Rate Malate Dehydrogenase Adipocytes Cyclic AMP Animals Humans Protein Isoforms Uncoupling Protein 1 Mice Knockout Receptors Thyroid Hormone Membrane Proteins Thermogenesis Adaptation Physiological Rats Cold Temperature Mice Inbred C57BL Gene Expression Regulation Liver Commentary Triiodothyronine Carrier Proteins |
| Zdroj: | The Journal of clinical investigation. 108(1) |
| ISSN: | 0021-9738 |
| Popis: | In newborns and small mammals, cold-induced adaptive (or nonshivering) thermogenesis is produced primarily in brown adipose tissue (BAT). Heat production is stimulated by the sympathetic nervous system, but it has an absolute requirement for thyroid hormone. We used the thyroid hormone receptor-beta--selective (TR-beta--selective) ligand, GC-1, to determine by a pharmacological approach whether adaptive thermogenesis was TR isoform--specific. Hypothyroid mice were treated for 10 days with varying doses of T3 or GC-1. The level of uncoupling protein 1 (UCP1), the key thermogenic protein in BAT, was restored by either T3 or GC-1 treatment. However, whereas interscapular BAT in T3-treated mice showed a 3.0 degrees C elevation upon infusion of norepinephrine, indicating normal thermogenesis, the temperature did not increase (0.5 degrees C) in GC-1--treated mice. When exposed to cold (4 degrees C), GC-1--treated mice also failed to maintain core body temperature and had reduced stimulation of BAT UCP1 mRNA, indicating impaired adrenergic responsiveness. Brown adipocytes isolated from hypothyroid mice replaced with T3, but not from those replaced with GC-1, had normal cAMP production in response to adrenergic stimulation in vitro. We conclude that two distinct thyroid-dependent pathways, stimulation of UCP1 and augmentation of adrenergic responsiveness, are mediated by different TR isoforms in the same tissue. |
| Databáze: | OpenAIRE |
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