Endocrine-Autonomic Linkages

Interaction between the autonomic nervous system and the neuroendocrine system is critical for maintenance of homeostasis in a wide variety of physiological parameters such as body temperature, fluid and electrolyte balance, and blood pressure and volume. The anatomical and physiological mechanisms underlying integration of the neuroendocrine and autonomic mechanisms responsible for eliciting integrated autonomic and neuroendocrine actions are the focus of this article. This includes a focus on the hypothalamic paraventricular nucleus, because it includes both neuroendocrine neurons and preganglionic autonomic neurons that regulate sympathetic and parasympathetic outflow. The "wired" and "nonwired" mechanisms within PVN that facilitate communication between these neuronal populations are described. The impact of peripheral hormones, specifically the adrenal and gonadal steroids, on the neuroendocrine and autonomic systems is discussed, and exercise is used as a specific example of a physiological challenge/stress that requires precise integration of neuroendocrine and autonomic responses to maintain cardiovascular, fluid, and energy homeostasis.