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Updated: Jul 19, 2026

Methods for the Discovery of Novel Compounds Modulating a Gamma-Aminobutyric Acid Receptor Type A Neurotransmission
Published on: August 16, 2018
Proenkephalin A and the gamma-aminobutyric acid A receptor pi subunit: expression, localization, and dynamic changes
Marisol Quezada1, Soledad Henríquez, Macarena Vargas
1Laboratorio de Inmunología de la Reproducción, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
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.
Design:
Prospective and observational, comparing prereceptive vs. receptive stages of secretory endometrium within the same nonconceptional menstrual cycle.
Setting:
University and non-governmental organization (NGO)-based academic and clinical-research facilities.
Patient(S):
Seven healthy, multiparous, surgically sterilized women with spontaneous regular menstrual cycles.
Intervention(S):
Endometrial biopsies were obtained on LH+3 and LH+7 within the same cycle.
Main Outcome Measure(S):
Levels of PEA and piGABA-R mRNA were determined by real-time PCR, and protein presence, by immunofluorescence.
Result(S):
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.
Conclusion(S):
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.
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