title: Hyperthyroidism advances luteolysis in the pregnant rat through changes in prostaglandin balance.
abstract: OBJECTIVE
  To investigate the underlying mechanisms implicated in the premature luteolysis induced by hyperthyroidism in pregnant rats.
  
  
  METHODS
  Experimental basic study.
  
  
  METHODS
  Research institute.
  
  
  METHODS
  Groups of 6-8 adult female Wistar rats were injected SC daily with T(4) (0.25 mg/kg) or vehicle, starting 8 days before mating, and killed by decapitation on days 19 (G19), 20 (G20), and 21 (G21) of pregnancy.
  
  
  METHODS
  Corpora lutea and truncal blood of control and hyperthyroid rats were obtained.
  
  
  METHODS
  Circulating and intraluteal hormones were determined by using RIA and luteal messenger RNA (mRNA) expression of enzymes and factors involved in P synthesis and metabolism by reverse transcriptase-polymerase chain reaction. 20α-Hydroxysteroid dehydrogenase (20αHSD) mRNA and protein expression was also determined by quantitative reverse transcriptase-polymerase chain reaction and Western blot.
  
  
  RESULTS
  Hyperthyroidism advanced luteolysis and 20αHSD expression induction by one day without changes in enzymes involved in P synthesis, decreased circulating E(2) and luteal estrogen receptor beta, and increased luteal prostaglandin F(2α) on G19 and G20 and prostaglandin E(2) on G19, while decreasing it on G20. Thus, decreased estrogenic influence and high prostaglandin F(2α)/prostaglandin E(2) ratio favors premature induction of 20αHSD on hyperthyroid rats.
  
  
  CONCLUSIONS
  Hyperthyroidism affects luteolysis in pregnant rats through alterations in luteal prostaglandin balance and decreased luteotrophic factors favoring the luteolytic action of prostaglandin F(2α) that induces premature 20αHSD expression that in turn advances circulating P fall and delivery.
authors.affiliation: Laboratorio de Reproducción y Lactancia, IMBECU-CONICET, Mendoza, Argentina.
authors.forename: Paola B
authors.initials: PB
authors.lastname: Navas
authors.forename: Alicia B
authors.initials: AB
authors.lastname: Motta
authors.forename: María B
authors.initials: MB
authors.lastname: Hapon
authors.forename: Graciela A
authors.initials: GA
authors.lastname: Jahn
mesh_terms: D000818:Animals; D005260:Female; D006980:Hyperthyroidism / Q000097:blood* / Q000150:complications*; D003341:Luteolysis / Q000097:blood*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood*; D011453:Prostaglandins / Q000097:blood*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D011453:Prostaglandins