| biochem/physiol actions: | Orexins (hypocretins) comprise a family of hypothalamic peptides that are involved in the initiation of sleep and in feeding behavior. Orexin A stimulates food intake through activation of the OX1 receptor. Orexin B activates OX2 receptors. Both OX1 and OX2 receptors are involved in maintaining arousal. OX2 receptors appear to be inhibitory autoreceptors on orexin-containing neurons. |