title: Effect of letrozole in carcinogen-plus-estrogen-induced endometrial hyperplasia in mice.
abstract: OBJECTIVE
  To evaluate the effects of letrozole (Ltz) in carcinogen+estrogen-induced endometrial hyperplasia.
  
  
  METHODS
  BALB/c female mice were divided into four groups of 12 animals each receiving an intrauterine dose of N-ethyl-N-nitrosourea (ENU) and weekly subcutaneous injections of estradiol hexaidrobenzoate (EHB), except for group I(control). The groups were divided in I (control), II (ENU+EHB), III (ENU+EHB+MPA) and IV (ENU+EHB+Ltz). Group III also received intramuscular injections of MPA (medroxy progesterone acetate) every four weeks, while group IV received oral doses of Ltz daily. At the end of 16 weeks, the animals were sacrificed, and blood samples were collected for the measurement of serum estradiol and progesterone levels. Uterine histological sections were made to evaluate the presence of endometrial proliferative lesions. Differences between groups were evaluated with student's t test, ANOVA and chi-square test.
  
  
  RESULTS
  Groups ENU+EHB, ENU+EHB+MPA and ENU+EHB+Ltz showed varying degrees of endometrial hyperplasia. The incidence of hyperplasia in groups ENU+EHB and ENU+EHB+Ltz was higher and more severe than in group ENU+EHB+MPA. Control group showed lower levels of serum estradiol than the other groups.
  
  
  CONCLUSIONS
  There was no evidence that letrozole could act as an antiestrogenic drug in the development of endometrial proliferative lesions.
authors.affiliation: Department of Obstetrics and Gynecology, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Alessandra Cerávolo
authors.initials: AC
authors.lastname: Lara
authors.affiliation: Department of Obstetrics and Gynecology, UFMG, Belo Horizonte, MG, Brazil.
authors.forename: Eduardo Batista
authors.initials: EB
authors.lastname: Cândido
authors.affiliation: Department of Pathology, UFMG, Belo Horizonte, MG, Brazil.
authors.forename: Paula Vieira
authors.initials: PV
authors.lastname: Vidigal
authors.affiliation: Department of Obstetrics and Gynecology, UFMG, Belo Horizonte, MG, Brazil.
authors.forename: Ana Luiza Lunardi
authors.initials: AL
authors.lastname: Rocha
authors.affiliation: Department of Obstetrics and Gynecology, UFMG, Belo Horizonte, MG, Brazil.
authors.forename: Alessandra Costa
authors.initials: AC
authors.lastname: Carvalho-Macedo
authors.affiliation: Department of Obstetrics and Gynecology, UFMG, Belo Horizonte, MG, Brazil.
authors.forename: Márcia Mendonça
authors.initials: MM
authors.lastname: Carneiro
authors.affiliation: Department of Obstetrics and Gynecology, UFMG, Belo Horizonte, MG, Brazil.
authors.forename: Agnaldo Lopes
authors.initials: AL
authors.lastname: Silva-Filho
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000209:etiology; D000818:Animals; D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology; D047072:Aromatase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D063646:Carcinogenesis / Q000187:drug effects* / Q000473:pathology; D004714:Endometrial Hyperplasia / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D016889:Endometrial Neoplasms / Q000188:drug therapy / Q000209:etiology; D004717:Endometrium / Q000187:drug effects / Q000473:pathology; D004958:Estradiol / Q000097:blood; D005038:Ethylnitrosourea; D005260:Female; D000077289:Letrozole; D017258:Medroxyprogesterone Acetate / Q000494:pharmacology; D008807:Mice, Inbred BALB C; D009570:Nitriles / Q000494:pharmacology* / Q000627:therapeutic use; D011374:Progesterone / Q000097:blood; D015203:Reproducibility of Results; D013997:Time Factors; D016896:Treatment Outcome; D014230:Triazoles / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D018931:Antineoplastic Agents, Hormonal; D047072:Aromatase Inhibitors; D009570:Nitriles; D014230:Triazoles; D011374:Progesterone; D004958:Estradiol; D000077289:Letrozole; D017258:Medroxyprogesterone Acetate; D005038:Ethylnitrosourea