Proenkephalin A and the gamma-aminobutyric acid A receptor pi subunit: expression, localization, and dynamic changes in human secretory endometrium.
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.
Quezada
Marisol
M
Laboratorio de Inmunología de la Reproducción, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
Henríquez
Soledad
S
Vargas
Macarena
M
Cardenas
Hugo
H
Tapia
Alejandro
A
Rios
Miguel
M
Salvatierra
Ana M
AM
Orihuela
Pedro A
PA
Croxatto
Horacio B
HB
Velasquez
Luis
L
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
D004745:Enkephalins; D011498:Protein Precursors; D021122:Protein Subunits; D011963:Receptors, GABA-A; C029992:proenkephalin