Roles of relaxin on cardiovascular system and its possible role in cardiovascular diseases

For the first half a century since its discovery, the peptide hormone Relaxin (RLX) encountered little attention as it was considered a pregnancy hormone only producing interpubic ligament elongation and uterine quiescence. Recently, however, RLX has emerged as an intriguing biological and pharmacological agent a very potent and intriguing bioactive agent and new promising pharmacological tool. It resembles insulin and insulin-like growth factors, its receptors have been well characterized as has as its main mechanism of action through AMP and nitric oxide (NO). The hormone is secreted into blood by the corpus luteum in pregnancy and during ovulatory cycles, although paracrine secretion has been found in several organs of both sexes. As it is active in heart, brain, uterus, lungs, kidneys, mammary gland, etc., RLX deserves to be called a ‘pleiotropic hormone’ and its widespread activities are consistent with the concept that it acts as the general manager of pregnancy, devoted to controlling and adjusting the body’s response to the obligatory increase in foeto-maternal needs that occur. In addition, there is evidence that RLX is active outside of pregnancy and in both sexes, particularly on the cardiovascular system (CVS). Based on the potent effects of RLX on the heart, vessels and blood, the results of experimental studies and the recent data from clinical trial in acute heart failure (AHF)(5) and ischemic-cardiovascular diseases (iCVD)(6,7,8 ) RLX is now recognized as a physiologic cardiovascular hormone it’s role as a novel therapy treating cardiovascular disease is currently an area of intense investigation.