title: Effects of melatonin on ovarian follicles.
abstract: OBJECTIVE
  To evaluate the histomorphometry and expression of Ki-67 and c-kit in ovarian follicles of pinealectomized or melatonin-treated pinealectomized rats.
  
  
  METHODS
  Forty adult rats were randomly divided into four groups of 10 animals: Group I - control; Group II - sham-pinealectomized; Group III - pinealectomized (Px), and Group IV - Px treated with melatonin (10μg/night, per animal). After two months' treatment, on the night of proestrous, the animals were placed in metabolic cages for night urine collection and subsequent measurement of 6-sulfatoxymelatonin (6-SMT). The rats were anesthetized, blood samples were taken for estrogen and progesterone determinations, and they were then euthanized. The ovaries were dissected out for further histological and immunohistochemical analyses. Data were first submitted to analysis of variance (ANOVA) complemented with the Tukey-Kramer test for multiple comparisons (P<0.05).
  
  
  RESULTS
  The urinary levels of 6-SMT and serum progesterone were lower in the Px group (GIII). Exogenous melatonin treatment restored both blood melatonin and 6-SMT urinary levels. The histomorphometric data in Group III revealed a significant increase of degenerating antral and non-antral follicles with regard to the other groups. In addition no corpora lutea were observed in this group. No significant differences were noticed regarding the number of corpora lutea among the other groups (I, II and IV), but the number of cells and the thickness of the theca interna of Px animals (Group III) were higher than in the other groups. Conversely, the density of progesterone receptors (fmol/g) in the ovaries of Group III was significantly lower than in the other groups.
  
  
  CONCLUSIONS
  Our data indicate that melatonin exerts a role on the maintenance of a proper follicular function, and is thus important for ovulation and progesterone production.
authors.affiliation: Department of Gynecology, São Paulo Federal University (UNIFESP), R. Borges Lagoa 783 - 3rd floor; Conj 31 - 04038-031 São Paulo, Brazil. kmasouza@hotmail.com
authors.forename: Carla Cristina
authors.initials: CC
authors.lastname: Maganhin
authors.forename: Luiz Fernando Portugal
authors.initials: LF
authors.lastname: Fuchs
authors.forename: Ricardo Santos
authors.initials: RS
authors.lastname: Simões
authors.forename: Ricardo Martins
authors.initials: RM
authors.lastname: Oliveira-Filho
authors.forename: Manuel
authors.initials: M
authors.lastname: de Jesus Simões
authors.forename: Edmund Chada
authors.initials: EC
authors.lastname: Baracat
authors.forename: José Maria
authors.initials: JM
authors.lastname: Soares
mesh_terms: D000818:Animals; D004958:Estradiol / Q000097:blood; D030762:Estrous Cycle; D005260:Female; D019394:Ki-67 Antigen / Q000378:metabolism*; D008550:Melatonin / Q000031:analogs & derivatives / Q000502:physiology* / Q000652:urine; D006080:Ovarian Follicle / Q000166:cytology / Q000502:physiology*; D010870:Pineal Gland / Q000601:surgery; D011374:Progesterone / Q000097:blood; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011987:Receptors, Steroid / Q000378:metabolism*
chemical_list: D019394:Ki-67 Antigen; D011987:Receptors, Steroid; C054513:6-sulfatoxymelatonin; D011374:Progesterone; D004958:Estradiol; D019009:Proto-Oncogene Proteins c-kit; D008550:Melatonin