title: Effect of long-time administration of tibolone on vaginal cytology of castrated rats.
abstract: OBJECTIVE
  To evaluate the estrogenic effect of tibolone administered at high-dose and long-term through cytological examination of vaginal epithelium of castrated rats.
  
  
  METHODS
  15 adult Wistar rats were submitted to bilateral oophorectomy 30 days before starting the experiment. The rats were then randomly divided in two groups. Experimental rats (n = 9) orally received 1 mg tibolone/day; control rats (n = 6) just received carboxymethylcellulose. Vaginal smears were collected from all rats on days 0, 1-6, 30, 60, 90 and 120 of the experiment.
  
  
  RESULTS
  On day 0, smears from all rats were atrophic, classified as anestrus, and remained this type in the control group until day 120. In the tibolone group, on day 3 all the rats had vaginal cytology similar to estrus and maintained the same aspect till day 90.
  
  
  CONCLUSIONS
  Tibolone has estrogenic action in the vaginal epithelium which is already evident after the first dose and remains without major changes over time.
authors.affiliation: Department of Pathology, Fluminense Federal University, UFF, Niteroi, RJ, Brazil. helenebiomed@yahoo.com.br
authors.forename: H N
authors.initials: HN
authors.lastname: Henriques
authors.forename: A C Bergmann
authors.initials: AC
authors.lastname: de Carvalho
authors.forename: J A S
authors.initials: JA
authors.lastname: Pantaleão
authors.forename: M A
authors.initials: MA
authors.lastname: Guzmán-Silva
mesh_terms: D000818:Animals; D004353:Drug Evaluation, Preclinical; D004848:Epithelium / Q000187:drug effects; D020847:Estrogen Receptor Modulators / Q000008:administration & dosage*; D005260:Female; D009652:Norpregnenes / Q000008:administration & dosage*; D010052:Ovariectomy; D051381:Rats; D014621:Vagina / Q000166:cytology / Q000187:drug effects*
chemical_list: D020847:Estrogen Receptor Modulators; D009652:Norpregnenes; C027385:tibolone