Relaxin: a pregnancy hormone as central player of body fluid and circulation homeostasis

The peptide relaxin has long been regarded as an important hormone of pregnancy, contributing to changes in connective tissue composition as well as to regulation of implantation, myometrial activity and labor. On the other hand, the astonishing pleiotropy of this hormone escaped scientific awareness. This review focuses on new facets of relaxin, including its antifibrotic effects, its role in the control of pituitary hormone release, its vasodilator and pro-angiogenic properties and its versatile myocardial actions. Recent progress in understanding relaxin's receptor and signaling mechanisms is also highlighted. The peptide will be characterized as potential regulator of body fluid and circulation homeostasis.