Thyroid & Thermogenesis
Thyroid Hormone & Themorgenesis
In a study done at the University of Miami, scientists found that the lack of thyroid hormone during development can cause a lack of thermogenesis in the future. The study was done on mice at the University of Miami Miller School of Medicine. Below is an abstract explaining the findings.
Abstract
Type 2 deiodinase (D2), which is highly expressed in brown adipose tissue (BAT), is an enzyme that amplifies thyroid hormone signaling in individual cells. Mice with inactivation of the D2 pathway (D2KO) exhibit dramatically impaired thermogenesis in BAT, leading to hypothermia during cold exposure and a greater susceptibility to diet-induced obesity. This was interpreted as a result of defective acute activation of BAT D2. Here we report that the adult D2KO BAT has a permanent thermogenic defect that stems from impaired embryonic BAT development. D2KO embryos have normal serum T3 but due to lack of D2-generated T3 in BAT, this tissue exhibits decreased expression of genes defining BAT identity [i.e. UCP1, PGC-1alpha and Dio2 (nonfunctional)], which results in impaired differentiation and oxidative capacity. Coinciding with a reduction of these T3-responsive genes, there is oxidative stress that in a cell model of brown adipogenesis can be linked to decreased insulin signaling and decreased adipogenesis. This discovery highlights the importance of deiodinase-controlled thyroid hormone signaling in BAT development, where it has important metabolic repercussions for energy homeostasis in adulthood.
Endocrinology. 2010 Jul 21. [Epub ahead of print]
Absence of Thyroid Hormone Activation during Development Underlies a Permanent Defect in Adaptive Thermogenesis.
Hall JA, Ribich S, Christoffolete MA, Simovic G, Correa-Medina M, Patti ME, Bianco AC.
Biological and Biomedical Sciences Program (J.A.H., A.C.B.), Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women’s Hospital (S.R., M.A.C.), and Research Division, Joslin Diabetes Center (M.E.P.), Harvard Medical School, Boston, Massachusetts 02115; and Division of Endocrinology, Diabetes, and Metabolism (G.S., M.C.-M., A.C.B.), University of Miami Miller School of Medicine, Miami, Florida 33136.