title: Leptin administration restores the fasting-induced increase of hepatic type 3 deiodinase expression in mice.
abstract: BACKGROUND
  Decreased serum leptin has been proposed as a critical signal initiating the neuroendocrine response to fasting. Leptin administration partially reverses the fasting-induced suppression of the hypothalamus-pituitary-thyroid axis at the central level. It is, however, unknown to what extent leptin affects peripheral thyroid hormone metabolism. The aim of this study was to evaluate the effect of leptin administration on starvation-induced alterations of peripheral thyroid hormone metabolism in mice.
  
  
  METHODS
  Three types of experiments were performed: (i) mice were fasted for 24 hours while leptin was administered twice (at 0 and 8 hours, 1 μg/g body weight [BW]), (ii) mice were fasted for 24 hours and, subsequently, leptin was given once at 24 hours (killed at 28 and 32 hours), and (iii) mice were fasted for 48 hours. All groups had appropriate controls. Serum triiodothyronine and thyroxine, liver type 1 deiodinase (D1), type 3 deiodinase (D3), thyroid hormone receptor (TR)β1, TRα1 and α2 mRNA expression, and liver D1 and D3 activity were measured.
  
  
  RESULTS
  Twenty-four hours of fasting decreased liver TRβ1 mRNA expression, while liver TRα1, TRα2, and D1 mRNA expression and activity did not change. In contrast, 24 hours of fasting increased liver D3 mRNA. Leptin administration after fasting restored liver D3 expression, while serum thyroid hormone levels and liver TRβ1 expression remained low.
  
  
  CONCLUSIONS
  Leptin administration selectively restores starvation-induced increased hepatic D3 expression independently of serum thyroid hormone concentrations. The present study shows that fasting-induced changes in mRNA expression of genes involved in hepatic hormone metabolism are influenced not only by decreased serum thyroid hormone levels but also by serum leptin.
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. a.boelen@amc.uva.nl
authors.forename: Anita
authors.initials: A
authors.lastname: Boelen
authors.forename: Mieke
authors.initials: M
authors.lastname: van Beeren
authors.forename: Xander
authors.initials: X
authors.lastname: Vos
authors.forename: Olga
authors.initials: O
authors.lastname: Surovtseva
authors.forename: Evita
authors.initials: E
authors.lastname: Belegri
authors.forename: Dirk-Jan
authors.initials: DJ
authors.lastname: Saaltink
authors.forename: Erno
authors.initials: E
authors.lastname: Vreugdenhil
authors.forename: Andries
authors.initials: A
authors.lastname: Kalsbeek
authors.forename: Joan
authors.initials: J
authors.lastname: Kwakkel
authors.forename: Eric
authors.initials: E
authors.lastname: Fliers
mesh_terms: D000818:Animals; D005215:Fasting / Q000097:blood / Q000378:metabolism*; D007453:Iodide Peroxidase / Q000096:biosynthesis*; D020738:Leptin / Q000008:administration & dosage* / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism; D037021:Thyroid Hormone Receptors alpha / Q000096:biosynthesis; D037042:Thyroid Hormone Receptors beta / Q000096:biosynthesis; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D015854:Up-Regulation
chemical_list: D020738:Leptin; D037021:Thyroid Hormone Receptors alpha; D037042:Thyroid Hormone Receptors beta; D014284:Triiodothyronine; C109812:iodothyronine deiodinase type I; C117274:iodothyronine deiodinase type III; D007453:Iodide Peroxidase; D013974:Thyroxine