title: What maintains the high intra-follicular estradiol concentration in pre-ovulatory follicles?
abstract: OBJECTIVE
  The purpose of the study was to establish the mechanism by which the estrogen concentration difference between the follicular fluid and the serum is maintained.
  
  
  METHODS
  We used dialysis membrane with a pore size of <3 KD to characterize the estrogen-binding capacity of the follicular fluid. We performed PCR, western blot, and ELISA on luteinized granulosa cells to determine if sex hormone-binding globulin (SHBG) is produced by granulosa cells, and finally we used affinity columns and mass spectrometry to identify the estrogen-binding protein in the follicular fluid.
  
  
  RESULTS
  We found that a significant estrogen concentration difference is maintained in a cell-free system and is lost with proteolysis of the follicular fluid proteins. Luteinized granulosa cells are likely not a source of SHBG, as we were not able to detect expression of SHBG in these cells. Perlecan was the most highly enriched follicular fluid protein in the affinity columns.
  
  
  CONCLUSIONS
  We were able to identify perlecan as the most likely candidate for the major estrogen-binding protein in the follicular fluid.
authors.affiliation: Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada. ybentov@tcart.ca.|Toronto Center for Assisted Reproductive Technologies, Toronto, Canada. ybentov@tcart.ca.|Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada. ybentov@tcart.ca.
authors.forename: Yaakov
authors.initials: Y
authors.lastname: Bentov
authors.affiliation: Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada.|Department of Physiology, University of Toronto, Toronto, Canada.|Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada.
authors.forename: Andrea
authors.initials: A
authors.lastname: Jurisicova
authors.affiliation: CReATe Fertility Centre, Toronto, Canada.|Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada.
authors.forename: Shlomit
authors.initials: S
authors.lastname: Kenigsberg
authors.affiliation: Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada.|Toronto Center for Assisted Reproductive Technologies, Toronto, Canada.|Department of Physiology, University of Toronto, Toronto, Canada.|Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Casper
mesh_terms: D004958:Estradiol / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D015571:Follicular Fluid / Q000378:metabolism; D006107:Granulosa Cells / Q000378:metabolism; D019812:Heparan Sulfate Proteoglycans / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D006080:Ovarian Follicle / Q000378:metabolism*; D044967:Serum / Q000378:metabolism; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*
chemical_list: D019812:Heparan Sulfate Proteoglycans; D012738:Sex Hormone-Binding Globulin; C071927:perlecan; D004958:Estradiol
keywords: Estrogen binding; Follicular fluid; Perlecan; SHBG