The orexin/hypocretin system: a critical regulator of neuroendocrine and autonomic function.

The hypocretins/orexins are hypothalamic peptides most recognized for their significant effects on feeding and arousal. Indeed, loss of the peptides results in a cataplexy quite similar to that observed canine models of human narcolepsy. However, neurons producing these peptides project to numerous brain sites known to be important in neuroendocrine regulation of pituitary function and autonomic centers as well. Results from numerous laboratories have suggested broad physiological roles for the hypocretins/orexins in neuroendocrine and autonomic regulation as a consequence of actions in the dorsal vagal complex, paraventricular nucleus, and pituitary. This review focuses upon evidence for potential physiologic roles for the peptides in these sites.