title: Attenuating activity of the ovary on LH response to GnRH during the follicular phase of the cycle.
abstract: OBJECTIVE
  Oestradiol sensitizes the pituitary to GnRH, while gonadotrophin surge attenuating factor (GnSAF) may oppose this action. Using the LH response to GnRH during treatment with FSH as an in vivo bioassay for GnSAF, we tested the hypothesis that the augmented LH response to GnRH in the late follicular phase is related to reduced production of GnSAF from the ovulatory follicle.
  
  
  METHODS
  Prospective intervention study.
  
  
  METHODS
  Ten healthy, normally cycling women.
  
  
  METHODS
  The LH response to 10 μg GnRH i.v. (ΔLH) was investigated on days 2 and 3 and on days v (follicle size 16-17 mm) and v + 1 of cycle 1 (control) and cycle 2. On days 2 and v, a single s.c. injection of either normal saline (cycle 1) or 450 IU recombinant FSH (cycle 2) was given after the end of the GnRH experiment.
  
  
  RESULTS
  FSH injection increased both serum oestradiol and inhibin B. In cycle 1, ΔLH remained unchanged from days 2 to 3 but increased significantly from days v to v + 1. In contrast, in cycle 2, ΔLH decreased significantly from days 2 to 3 (P < 0·05) and showed a nonsignificant increase from day v to day v + 1. The percentage difference in ΔLH between cycle 1 and cycle 2 was similar on days 3 (-66·9 ± 17·5%) and v + 1 (-65·2 ± 3·6%).
  
  
  CONCLUSIONS
  These results suggest that during the follicular phase of the menstrual cycle, GnSAF is produced by small antral follicles, while the contribution of the ovulatory follicle is minimal.
authors.affiliation: Department of Obstetrics and Gynaecology, Faculty of Medicine, School of Health Sciences, University of Thessalia, Larissa, Greece; Department of Obstetrics and Gynaecology, Medical School, University of Thrace, Alexandroupolis, Greece.
authors.forename: Marina
authors.initials: M
authors.lastname: Dimitraki
authors.forename: Christina I
authors.initials: CI
authors.lastname: Messini
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Dafopoulos
authors.forename: Theodora
authors.initials: T
authors.lastname: Gioka
authors.forename: Nikoletta
authors.initials: N
authors.lastname: Koutlaki
authors.forename: Antonios
authors.initials: A
authors.lastname: Garas
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Georgoulias
authors.forename: Ioannis E
authors.initials: IE
authors.lastname: Messinis
mesh_terms: D000328:Adult; D048429:Cell Size / Q000187:drug effects; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005498:Follicular Phase / Q000097:blood / Q000187:drug effects*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D007265:Inhibins / Q000097:blood; D007986:Luteinizing Hormone / Q000378:metabolism*; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects; D010053:Ovary / Q000187:drug effects* / Q000378:metabolism*; D011374:Progesterone / Q000097:blood; D055815:Young Adult
chemical_list: C422364:inhibin B; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone