[The study of endothelin and endothelin receptors in cyclic human endometrium]

To determine the distribution of endothelin (ET) peptide and endothelin as well as their receptors (ETaR and ETbR) mRNA in human cycling endometrium in order to assess possible role of ET in endometrial reproductive physiology.

Twenty-three endometrial specimens from gynecological surgery for benign conditions were studied by means of immunohistochemistry, in situ hybridization and computer quantitative image analysis.

The expression of ET peptide and ET mRNA in human endometrium varies throughout the menstrual cycle, increasing gradually from proliferative phase to secretory phase, with maximal levels in the pre-menstrual phase. Stromal expression is lower than in glandular epithelium and remains relatively constant in the menstrual cycle. ETaR and ETbR mRNA are detected in normal human endometrium, higher in glandular epithelial cells than in stromal cells. ETaR mRNA expression has no obvious cyclic changes, but ETbR mRNA expressions are higher in secretory endometrium than in proliferative endometrium. The ratio of ETaR/ETbR has also cyclic changes.

Changes of Expression of ET and ET receptors in the endometrium throughout the menstrual cycle suggest that ET might be important in endometrial regeneration and repair following menstruation, and probably plays a role as the paracrine control of the uterine vascular bed.