The emerging concept of relaxin as a centrally acting peptide hormone with hemodynamic actions.

The novel finding that relaxin has an action on the brain was first published in 1984. Since then, it has been shown that exogenous relaxin affects the release of a number of hypothalamo-pituitary hormones and has a robust pressor action. In this paper, we review the accumulating evidence that relaxin affects the release of oxytocin and vasopressin by an action at the level of the brain. The potential mechanisms of this central action are discussed and the evidence presented for the interaction between relaxin and the forebrain angiotensin-II system. Furthermore, we articulate the possible physiological influences of relaxin on the changes in cardiovascular function that occur during pregnancy.