Increased Salt Sensitivity in Obese Hypertension: Role of the Sympathetic Nervous System

Salt sensitivity of blood pressure (BP) is increased in hypertension associated with obesity and/or metabolic disorders. Reversely, patients with salt-sensitive hypertension often reveal metabolic disorders. Thus, salt excess and overeating, which are major bad dietary habits in civilized men and women, strengthen the effect to increase BP each other. Actually, there are similar pathophysiological characteristics between hypertension induced by high salt intake and obesity: the sympathetic excitation has been suggested to contribute to increase in BP of the two types of hypertension. Also, several investigators indicated that reactive oxygen species (ROS) production is increased in important organs of salt-sensitive and/or obese hypertension. Recently, we demonstrated that, in salt- and obesity-induced hypertension, hypothalamic ROS levels was elevated and intracerebroventricular antioxidants suppress BP and renal sympathetic nerve activity more profoundly, compared to their control. Thus, it is suggested that brain ROS overproduction increases BP through central symapthoexcitation in salt- and obesity-induced hypertension, which are often associated.