____________________________________________________________________________________________ *Corresponding author: E-mail: mostafaranda@sharjah.ac.ae; Cardiology and Angiology: An International Journal 2(1): 49-61, 2014, Article no.CA.2014.004 SCIENCEDOMAIN international www.sciencedomain.org Prolactin Hormone and Cardiovascular System R. M. Mostafa 1* , K. M. Moustafa 2 , Z. Mirghani 1 and Y. M. Moustafa 3 1 Department of Basic Medical Sciences, College of Medicine, Sharjah University, United Arab Emirates. 2 Department of Clinical Sciences, College of Medicine, Sharjah University, United Arab Emirates. 3 Department of Pharmacology and Toxicology, College of Pharmacy, Suez Canal University, Egypt. Authors’ contributions This work was carried out in collaboration between all authors. All authors read and approved the final manuscript. Received 13 th December 2013 Accepted 15 th March 2014 Published 28 th March 2014 ABSTRACT The Prolactin (PRL) hormone, a very ancient hormone, first discovered by Oscar Riddle and his colleagues in the late 1920s, is a 199 amino acid multifunctional polypeptide hormone, that has been found in all vertebrates to influence more than 300 physiologic functions of the body. This review discusses the prolactin structure, mechanism of synthesis, control of secretions, receptors, its intracellular signal transduction and its possible implications on the cardiovascular system. Keywords: Prolactin; cardiovascular system; signal transduction; pregnancy. 1. INTRODUCTION Prolactin is a multifunctional hormone whose receptors are expressed in almost all organs of human body which in turn enables it to influence multiple physiological processes including endocrine, metabolic, immune system functions and cardiovascular properties. In comparison with the majority of the pituitary hormones, Prolactin is found to have the most physiological functions [1], estimated at approximately 300 different biological actions in vertebrates [2]. Mini-review Article