title: Regulation of peptide YY levels by age, hormonal, and nutritional status.
abstract: OBJECTIVE
  Peptide YY (PYY) 3-36 has recently been recognized as an important gut hormone that influences food intake. Peripheral injections of PYY 3-36 in rats inhibit food intake in experimental animals as well as in lean and obese human subjects. This hormone has been suggested as an attractive therapeutic option for obesity. The aim of this study was to assess the influence of age, sex, thyroid status, growth hormone (GH), pregnancy, and food restriction on PYY levels in rat.
  
  
  METHODS
  We determined plasma PYY levels in all experimental sets.
  
  
  RESULTS
  PYY levels were influenced by age, with the highest hormone levels achieved in early postnatal life (day 10) and decreasing thereafter. PYY levels were also dependent on thyroid hormone status being decreased in hyperthyroid rats. Exogenous GH administration led to a clear-cut decrease in PYY levels in both normal and GH-deficient rats. Acute food deprivation or chronic food restriction led to decreased PYY levels in virgin and pregnant rats. In pregnant rats with food available ad libitum, PYY levels were enhanced at late gestation.
  
  
  CONCLUSIONS
  Our observations indicate that PYY levels are influenced by age, thyroid hormones, and GH. These data indicate that PYY could be involved in the changes of food intake associated with these conditions. The PYY levels observed in acute and chronic food-restricted rats indicate that, in situations of decreased energy intake, the lower PYY levels could serve to disinhibit central pathways and facilitate food intake.
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Santiago de Compostela, Spain.
authors.forename: Sulay A
authors.initials: SA
authors.lastname: Tovar
authors.forename: Luisa M
authors.initials: LM
authors.lastname: Seoane
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Caminos
authors.forename: Rubén
authors.initials: R
authors.lastname: Nogueiras
authors.forename: Felipe F
authors.initials: FF
authors.lastname: Casanueva
authors.forename: Carlos
authors.initials: C
authors.lastname: Diéguez
mesh_terms: D000375:Aging; D000818:Animals; D005260:Female; D005508:Food Deprivation; D005865:Gestational Age; D013006:Growth Hormone / Q000008:administration & dosage / Q000172:deficiency; D006706:Homeostasis; D006728:Hormones / Q000502:physiology*; D006980:Hyperthyroidism / Q000097:blood; D008297:Male; D009752:Nutritional Status; D019894:Peptide YY / Q000097:blood*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics
chemical_list: D006728:Hormones; D019894:Peptide YY; D013006:Growth Hormone