miRNAs in Neurohormonal Activation

This chapter aims to introduce the role of miRNAs in regulating neurohormonal activation. The natural progression of heart failure is accompanied by the compensatory activation of cardiac and extracardiac neurohormonal systems and changes in the anatomy and function of the left ventricle. An array of biologically active molecules belong to the sympathetic adrenergic nervous system (norepinephrine) and renin–angiotensin– aldosterone system (RAS) (Ang II and aldosterone), which are responsible for maintaining cardiac output through increased retention of salt and water, peripheral arterial vasoconstriction, and contractility, as well as inflammatory mediators that are responsible for cardiac repair and remodeling. Although, the role of miRNAs in regulating the components of RAS and the adrenergic system is still poorly not well understood, several recent observations are worth noting. In particular, miR-155 is implicated in suppressing the levels of the Ang II type 1 receptor, and miR-21 can increase aldosterone secretion in human adrenal cells. This chapter describes very limited information in this regard.