Cardiovascular Regulation by the Arcuate Nucleus of the Hypothalamus

The importance of the central nervous system in cardiovascular regulation is well established. The brain is able to sense changes that occur in the peripheral circulation through several mechanisms, including afferent neural reflexes and humoral signals. The brain in turn can adjust various components of the cardiovascular system to maintain homeostasis by modulating the release of critical hormonal factors, chemical messengers, and neurotransmitters in concert with changing the activity of the sympathetic and parasympathetic branches of the autonomic nervous system subserving different organs and tissues throughout the body. It has long been recognized that brain regulation of the cardiovascular system involves complex networks of neurons located in the brain stem, midbrain, and forebrain. Among the various brain structures involved in circulatory regulation, the hypothalamus plays a central role by integrating the information conveyed via various signal inputs with the neural networks involved to determine and coordinate the appropriate responses to maintain homeostasis. Much of the investigation of the cardiovascular regulation by the hypothalamus has focused on the paraventricular, dorsomedial, lateral, and posterior nuclei. Consequently, there is a wealth of information about the anatomic, cellular, and molecular processes underlying the control of autonomic and cardiovascular functions by these hypothalamic nuclei, particularly the paraventricular nucleus. The arcuate nucleus of the hypothalamus (ARC) is emerging as a major player in cardiovascular and sympathetic regulation. I will review the neuroanatomical and cellular characteristics of the ARC before discussing the evidence that implicates the ARC in the control of blood pressure and sympathetic outflow.