title: Expression pattern of endothelin system components and localization of smooth muscle cells in the human pre-ovulatory follicle.
abstract: BACKGROUND
  Whether ovarian follicular rupture involves contractile activity or not has been debated for decades. Recently, study in the rodents has indicated that an endogenously produced potent vasoconstrictive peptide, endothelin-2 (EDN2), may induce follicular constriction immediately prior to ovulation. This study was aimed to systematically characterize the human ovarian endothelin system and localize smooth muscle cells to assess the possible involvement of contractile activity in human ovulation.
  
  
  METHODS
  This is a prospective experimental study. Study subjects were 20 women aged 20-38 years who underwent IVF owing to tubal or male factors. Expression patterns of messenger RNAs (mRNAs) for EDN1, EDN2, EDN3, endothelin-converting enzyme-1 (ECE1 and ECE2), endothelin receptor A (ET(A)) and ET(B) in the granulosa cells (GCs) and cumulus cells and endothelin peptide concentration in the pre-ovulatory follicles were measured at 36 h after hCG injection. In addition, localization of ovarian smooth muscle cells and endothelin receptor expression were determined in normal (non-IVF patient) ovaries.
  
  
  RESULTS
  Pre-ovulatory follicles express mRNA for EDN1 and EDN2, ECE1, ECE2, ET(A) and ET(B), but not EDN3, contain highly concentrated endothelin peptides (105.9 pg/ml) and are surrounded by theca externa that are made mostly of multicell layer non-vascular smooth muscle cells. ET(A) expression is localized in the smooth muscle cells of theca externa, theca interna and GC, whereas ET(B) expression is confined to theca interna.
  
  
  CONCLUSIONS
  Pre-ovulatory follicles contain highly concentrated endothelins and are surrounded by non-vascular smooth muscle cells that express endothelin receptor, suggesting involvement of endothelin-induced contractile action in ovulation in the human ovary.
authors.affiliation: Department of Obstetrics and Gynaecology, CHA University, Bundang-Si, Kyounggi-do, Republic of Korea.
authors.forename: Dong-Hee
authors.initials: DH
authors.lastname: Choi
authors.forename: Eun Kyung
authors.initials: EK
authors.lastname: Kim
authors.forename: Kyeoung-Hwa
authors.initials: KH
authors.lastname: Kim
authors.forename: Kyung-Ah
authors.initials: KA
authors.lastname: Lee
authors.forename: Dong-Wook
authors.initials: DW
authors.lastname: Kang
authors.forename: Hey Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Phillip
authors.initials: P
authors.lastname: Bridges
authors.forename: Chemyong
authors.initials: C
authors.lastname: Ko
mesh_terms: D000328:Adult; D016282:Aspartic Acid Endopeptidases / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D054885:Cumulus Cells / Q000378:metabolism; D000072396:Endothelin-Converting Enzymes; D016232:Endothelins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005307:Fertilization in Vitro; D015571:Follicular Fluid / Q000378:metabolism; D006107:Granulosa Cells / Q000378:metabolism; D006801:Humans; D008666:Metalloendopeptidases / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology*; D006080:Ovarian Follicle / Q000166:cytology / Q000378:metabolism*; D010060:Ovulation; D012333:RNA, Messenger / Q000378:metabolism; D017466:Receptors, Endothelin / Q000032:analysis / Q000235:genetics / Q000378:metabolism
chemical_list: D016232:Endothelins; D012333:RNA, Messenger; D017466:Receptors, Endothelin; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; C000606923:ECE1 protein, human; C000606924:ECE2 protein, human; D000072396:Endothelin-Converting Enzymes