title: Thyroid hormone signaling and homeostasis during aging.
abstract: Studies in humans and in animal models show negative correlations between thyroid hormone (TH) levels and longevity. TH signaling is implicated in maintaining and integrating metabolic homeostasis at multiple levels, notably centrally in the hypothalamus but also in peripheral tissues. The question is thus raised of how TH signaling is modulated during aging in different tissues. Classically, TH actions on mitochondria and heat production are obvious candidates to link negative effects of TH to aging. Mitochondrial effects of excess TH include reactive oxygen species and DNA damage, 2 factors often considered as aging accelerators. Inversely, caloric restriction, which can retard aging from nematodes to primates, causes a rapid reduction of circulating TH, reducing metabolism in birds and mammals. However, many other factors could link TH to aging, and it is these potentially subtler and less explored areas that are highlighted here. For example, effects of TH on membrane composition, inflammatory responses, stem cell renewal and synchronization of physiological responses to light could each contribute to TH regulation of maintenance of homeostasis during aging. We propose the hypothesis that constraints on TH signaling at certain life stages, notably during maturity, are advantageous for optimal aging.
authors.affiliation: Muséum national d'Histoire Naturelle, Laboratoire de Physiologie Générale et Comparée, Unité Mixte de Recherche, Centre National de la Recherche Scientifique 7221, 75231 Paris cedex 5, France.
authors.forename: J
authors.initials: J
authors.lastname: Bowers
authors.forename: J
authors.initials: J
authors.lastname: Terrien
authors.forename: M S
authors.initials: MS
authors.lastname: Clerget-Froidevaux
authors.forename: J D
authors.initials: JD
authors.lastname: Gothié
authors.forename: M P
authors.initials: MP
authors.lastname: Rozing
authors.forename: R G J
authors.initials: RG
authors.lastname: Westendorp
authors.forename: D
authors.initials: D
authors.lastname: van Heemst
authors.forename: B A
authors.initials: BA
authors.lastname: Demeneix
mesh_terms: D000375:Aging; D000818:Animals; D006706:Homeostasis; D006801:Humans; D007031:Hypothalamus / Q000254:growth & development / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D011988:Receptors, Thyroid Hormone / Q000378:metabolism*; D015398:Signal Transduction; D013961:Thyroid Gland / Q000254:growth & development / Q000378:metabolism; D013963:Thyroid Hormones / Q000097:blood / Q000378:metabolism*
chemical_list: D011988:Receptors, Thyroid Hormone; D013963:Thyroid Hormones