title: The long-term regulation of food intake and body weight depends on the availability of thyroid hormones in the brain.
abstract: OBJECTIVE
  We evaluated the contribution of the thyroid hormones to the long-term maintenance of feeding behavior and body weight, while distinguishing their direct central effects from those resulting from the metabolic rate in the peripheral tissues.
  
  
  METHODS
  We assessed the effect of hypothyroidism on the long-term (6 months) regulation of food intake, body weight, and energy expenditure in rats. We then generated the recovery of a euthyroid condition in the brain while maintaining a low T3 availability for the peripheral organs, i.e. a combined condition of central euthyroidism with peripheral hypothyroidism, with the aid of a pharmacological combination.
  
  
  RESULTS
  Hypothyroidism caused a decrease in the daily food intake, body weight, and body temperature. The food intake and body temperature stabilized at a lower value, whereas body weight kept decreasing at a constant rate. The administration of exogenous T4 increased food intake and body-weight gain, but had no effect on body temperature.
  
  
  CONCLUSIONS
  The thyroid hormones are necessary for the long-term regulation of energy intake, storage, and expenditure by different mechanisms. The feeding behavior seems to be partially dependent on a direct action of the thyroid hormones on the brain and this effect is independent of the energy expenditure in the peripheral organs. The body weight is closely dependent on the thyroid status and its maintenance seems to involve thyroid action on mechanisms other than feeding and metabolic rate.
authors: Departamento de Fisiología, Instituto Politécnico Nacional, Mexico.
authors: Claudia
authors: C
authors: Alva-Sánchez
authors: Jorge
authors: J
authors: Pacheco-Rosado
authors: Tomás
authors: T
authors: Fregoso-Aguilar
authors: Iván
authors: I
authors: Villanueva
mesh_terms: D000818:Animals; D013956:Antithyroid Agents / Q000494:pharmacology; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001835:Body Weight / Q000187:drug effects / Q000502:physiology*; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology*; D004435:Eating / Q000187:drug effects / Q000502:physiology*; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology; D007037:Hypothyroidism / Q000139:chemically induced / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008713:Methimazole / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013974:Thyroxine / Q000097:blood* / Q000494:pharmacology; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D013956:Antithyroid Agents; D014284:Triiodothyronine; D008713:Methimazole; D013974:Thyroxine