New Insights into the Pathophysiology of Sickle Cell Disease-Associated Priapism

Introduction. Priapism is defined as an erectile disorder, in which erection persists uncontrollably without sexual purpose. The precise mechanisms involved in the development of sickle cell disease-associated priapism are ill defined. Aim. To summarize the recent developments that increase our understanding of the molecular mechanisms of priapism. Methods. This article reviews the literature (Medline search 2000-2010) that relates the key molecular signaling pathways that contribute to the development of priapism associated with sickle-cell disease. It focuses on basic science investigations using multiple animal models. Main Outcome Measures. The reader will be informed of the most current research regarding the role of endothelial nitric oxide synthase, phosphodiesterase type 5 (PDE5), adenosine, RhoA/Rho-kinase (ROCK), and opiorphins in the pathophysiology of priapism. Results. New concepts in the field of priapism research suggest that priapism often results from altered vascular homeostatic actions in the penis and is associated with deficient erection control mechanisms on a molecular level. A leading proposal in this regard is the notion of aberrant signaling of the endothelium-derived nitric oxide and PDE5 signal transduction pathway in the penis. Additionally, dysfunctional regulatory control of signal transduction systems which interact with this pathway such as adenosine and RhoA/Rho-kinase may contribute to the development of priapism. Recent investigations of opiorphins also demonstrate a role in regulating corporal smooth muscle tone and thereby dysregulation of erection physiology in priapism. These advances have paved the way for understanding this disorder as having a molecular pathogenesis. Conclusions. As the science underlying priapism further emerges, increasingly effective therapeutics for sickle cell disease-associated priapism is certain to follow.