Indeed, studies have suggested that chronic exposure to stress may have an influence on increased blood pressure, elevated blood glucose levels and an increased risk for heart disease, which is mediated through the symptomatic nervous system, the hypothalamic–pituitary–adrenal axis, and the renin–angiotensin–aldosterone system (Surwit and Schneider, 1992, Gasperin et al., 2009). Here, REN is linked to heart disorder.