The preoptic anterior hypothalamus is the portion of the human brain that regulates temperature. The thermosensitive neurons located in the preoptic anterior hypothalamus receive information about peripheral and core temperature from skin thermoreceptors, mucus membrane, spinal receptors, the hypothalamus and endogenous substances like pyrogens, progesterone and glucose. These neurons then process and integrate the temperature information to cause a thermoregulatory response that can maintain temperature homeostasis. The thermoregulatory response involves increasing or decreasing the activity of warm sensitive neurons and cold sensitive neurons, catecholamine release, thyroid modulation, shivering, behavioral changes, and peripheral vasoconstriction or dilation.
General anesthesia affects the preoptic anterior hypothalamus by interfering with the body’s ability to effectively regulate heat production and heat loss. As a result patients undergoing general anesthesia are prone to intraoperative and postoperative hypothermia which can lead to postoperative shivering. Thus active warming measures such as forced air warming blankets are an important part of helping patients maintain appropriate core temperatures.
Boulant J. Role of the preoptic-anterior hypothalamus in thermoregulation and fever. Clin Infect Dis 2000 Oct.:S157-61.