Endometrial Expression of Relaxin and Relaxin Receptor in Endometriosis

Abstract

Relaxin is a peptide discovered since 1926 by Hisaw. Belongs to the super family of structurally related hormones including: relaxin-1, -2 and -3 and insulin-like (INSL) peptides 3, 4, 5 and 6 and has important roles in follicle growth and ovulation, in implantation of the egg, preparation of the endometrium for implantation, in uterine growth in pregnancy, in inhibiting the myometrium contractile activity, in the procession of lactation and also exerts a protective effect in endometriosis. The relaxin family peptides produce their physiological effects by activating a group of four G protein-coupled receptors, relaxin family peptide receptors 1-4 (RXFP1-4). Relaxin regulates the expression of matrix metalloproteinase’s (MMPs), a group of enzymes that degrade the extracellular matrix, essential for invasion of endometrial cells in peritoneum and also the expression of the vascular endothelial growth factor (VEGF), a glycoprotein with vasculogenic regulatory role in endometriosis by determining an excessive angiogenesis. MMPs and VEGF are both over expressed in the ectopic endometrial tissue of patients with endometriosis. Blocking the production of VEGF and MMPs appear to be effective and specific means of treatment in endometriosis.