Diminished endometrial expression of ghrelin and ghrelin receptor contributes to infertility.

The objectives were to investigate the presence, distribution and sex steroid hormone regulation of ghrelin and its receptor, growth hormone secretagogue receptor (GHSR), in human endometrium in relation to endometrial receptivity and fertility. Endometrial biopsies were obtained from women with unexplained infertility and healthy fertile volunteers. Ishikawa cells were used to mimic the action of ghrelin in endometrium. Immunostaining of GHSR was strong in luminal epithelium and stroma during mid-secretory phase. Ghrelin and GHSR expression is less intense in mid-secretory endometrium of infertile women compared to fertile controls. Treatment with estrogen and/or progesterone or their antagonists did not significantly change the relative expression of GHSR in Ishikawa and stromal cells. Ghrelin was present in and secreted from human blastocysts, which suggest that the communication between human blastocyst and endometrium might involve ghrelin. Low levels of GHSR in endometrium from women with unexplained infertility may in part explain the infertility.