CRH-Like Peptides in Human Reproduction

CRH and Urocortins 1, 2 and 3 comprise the, so far identified, members of the CRH family of peptides in humans. Their actions are mediated through two distinct receptors, CRHR1 and CRHR2, encoded by different genes. CRH-like peptides and their receptors have been identified in reproductive tissues, such as the ovary, uterus as well as fetal and placental membranes. The participation of the CRH family of peptides and receptors in the physiology of these organs is currently under intense investigation. During the estrus cycle, endometrial CRH acts as a fine tuner of stromal cells decidualization. CRH is produced by embryonic trophoblast and maternal decidual cells and plays important roles in implantation. CRH also participates in the control of trophoblast invasion. Furthermore, placental CRH and Urocortin are involved in the mechanisms controlling maintenance of pregnancy and the onset of labor. The level of participation of urocortins 2 and 3 in these phenomena is currently under investigation. This review will focus on existing data on the expression and regulation of the CRH family of peptides and their receptors in the female reproductive system, as well as in their potential biologic role(s) in human reproductive functions.