Effects of long-term food reduction on the hypothalamus-pituitary-thyroid axis in male and female rats

Détails

ID Serval
serval:BIB_D94FD0819513
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Effects of long-term food reduction on the hypothalamus-pituitary-thyroid axis in male and female rats
Périodique
Journal of Endocrinology
Auteur(s)
van Haasteren  G. A., Linkels  E., van Toor  H., Klootwijk  W., Kaptein  E., de Jong  F. H., Reymond  M. J., Visser  T. J., de Greef  W. J.
ISSN
0022-0795
Statut éditorial
Publié
Date de publication
08/1996
Peer-reviewed
Oui
Volume
150
Numéro
2
Pages
169-78
Notes
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Aug
Résumé
The reduced thyroid activity during short-term starvation is associated with a lowered hypothalamic synthesis and secretion of TRH. However, little is known about the cause of the reduced thyroid function during prolonged malnutrition. We have therefore studied the effects of food reduction to one-third of normal (FR33) on the hypothalamus-pituitary-thyroid axis of male and female Wistar rats. After 3 weeks body weights of FR33 rats were almost 50% lower than those of controls. In both sexes, FR33 caused marked increases in serum corticosterone, and decreases in serum TSH, thyroxine (T4), free T4, tri-iodothyronine (T3) and free T3. While the free T3 fraction (FFT3) in serum decreased, the free T4 fraction (FFT4) tended to increase. Electrophoretic analysis indicated that decreased FFT3 was correlated with an increased thyroxine-binding globulin, while the increase in FFT4 seemed due to a decreased thyroxine-binding prealbumin binding capacity. Total RNA and proTRH mRNA in the hypothalamus were not affected by FR33. Median eminence and posterior pituitary TRH content tended to increase in FR33 rats, suggesting that hypothalamic TRH release is reduced in FR33 rats. Anterior pituitary TSH content was decreased by FR33 in both sexes, but pituitary TSH beta mRNA and TRH receptor status were not affected except for increased pituitary TSH beta mRNA in female FR33 rats. Although FR33 had no effect on pituitary weight, pituitary RNA and membrane protein content in FR33 rats were 50-70% lower than values in controls. In conclusion, prolonged food reduction suppresses the pituitary-thyroid axis in rats. In contrast to short-term food deprivation, the mechanism whereby serum TSH is suppressed does not appear to involve decreases in proTRH gene expression, but may include effects on pituitary mRNA translation. Our results further support the hypothesis that TSH release may be lowered by increased corticosterone secretion, although the mechanism of this effect may differ between acute starvation and prolonged food reduction.
Mots-clé
Animals Body Weight Corticosterone/blood Female Food Deprivation/*physiology Hypothalamo-Hypophyseal System/*physiopathology Male Pituitary Gland/chemistry/metabolism Protein Precursors/genetics Pyrrolidonecarboxylic Acid/analogs & derivatives RNA, Messenger/analysis Rats Rats, Wistar Thyroid Gland/*physiopathology Thyrotropin/blood Thyrotropin-Releasing Hormone/genetics/metabolism Thyroxine/blood Triiodothyronine/blood
Pubmed
Web of science
Création de la notice
11/02/2008 15:12
Dernière modification de la notice
03/03/2018 21:52
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