title: Proenkephalin A and the gamma-aminobutyric acid A receptor pi subunit: expression, localization, and dynamic changes in human secretory endometrium.
abstract: OBJECTIVE
  To compare mRNA and protein levels of proenkephalin A (PEA) and gamma-aminobutyric acid A receptor pi subunit (piGABA-R) in human secretory endometrium before and during receptivity and to determine the cell phenotypes where they are expressed.
  
  
  METHODS
  Prospective and observational, comparing prereceptive vs. receptive stages of secretory endometrium within the same nonconceptional menstrual cycle.
  
  
  METHODS
  University and non-governmental organization (NGO)-based academic and clinical-research facilities.
  
  
  METHODS
  Seven healthy, multiparous, surgically sterilized women with spontaneous regular menstrual cycles.
  
  
  METHODS
  Endometrial biopsies were obtained on LH+3 and LH+7 within the same cycle.
  
  
  METHODS
  Levels of PEA and piGABA-R mRNA were determined by real-time PCR, and protein presence, by immunofluorescence.
  
  
  RESULTS
  The mRNA level of PEA fell, whereas that of piGABA-R increased, during endometrial receptivity. Positive immunostaining of PEA was found in the luminal and glandular epithelium, whereas that of piGABA-R was in luminal epithelium and stromal cells.
  
  
  CONCLUSIONS
  The discrete cell-phenotype localization and timing of the changes in the level of PEA and of piGABA-R mRNA and protein suggest an important role for these molecules in switching the human endometrium from a refractory to a receptive state.
authors.affiliation: Laboratorio de Inmunología de la Reproducción, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
authors.forename: Marisol
authors.initials: M
authors.lastname: Quezada
authors.forename: Soledad
authors.initials: S
authors.lastname: Henríquez
authors.forename: Macarena
authors.initials: M
authors.lastname: Vargas
authors.forename: Hugo
authors.initials: H
authors.lastname: Cardenas
authors.forename: Alejandro
authors.initials: A
authors.lastname: Tapia
authors.forename: Miguel
authors.initials: M
authors.lastname: Rios
authors.forename: Ana M
authors.initials: AM
authors.lastname: Salvatierra
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Orihuela
authors.forename: Horacio B
authors.initials: HB
authors.lastname: Croxatto
authors.forename: Luis
authors.initials: L
authors.lastname: Velasquez
mesh_terms: D000328:Adult; D004717:Endometrium / Q000378:metabolism*; D004745:Enkephalins / Q000378:metabolism*; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D008183:Luteal Phase / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D004745:Enkephalins; D011498:Protein Precursors; D021122:Protein Subunits; D011963:Receptors, GABA-A; C029992:proenkephalin