Targeting sigma-1 receptor signaling by endogenous ligands for cardioprotection

Introduction: The sigma receptors, initially described as a subtype of opioid receptors, are now considered to be a unique receptor expressed in neonatal rat cardiomyocytes and in the plasma membrane of adult rat cardiomyocytes. A number of sigma receptor ligands influence cardiovascular function and the heart has binding sites for sigma receptor ligands that alter contractility both in vivo and in vitro. The human sigma-1 receptor gene contains a steroid-binding component and gonadal steroid dehydroepiandrosterone (DHEA) which interacts with the sigma-1 receptor. Areas covered: We recently documented that the pathophysiological role of the sigma-1 receptor in the heart and its modulation using DHEA, was cardioprotective. Moreover, agonist-induced activation of the sigma-1 receptor modulates diverse ion channels and thereby regulates heart function. Novel concepts for understanding the pathophysiological relevance of sigma-1 receptors in the progression of heart failure, and developing clinical therapeutics targeting for the receptor in cardiovascular diseases are discussed. Expert opinion: Future studies should attempt to develop cardiac-specific knockdown of the sigma-1 receptor to observe its downstream signaling. We expect that these observations will lead to a novel therapeutic target for which a new class of antihypertrophic drugs can be designed.