Orexin A has been used to study its effect on serum luteinizing hormone (LH) concentration in lateral ventricle in ovariectomized (OVX) gilts and is used to study the behavioral and metabolic effects of central injections of orexin A on pigeons (Columba livia).
Orexin A, also known as hypocretin 1 (hcrt1), is a 33 amino acid excitatory neuropeptide, localized in a small set of neurons in the perifornical area of the hypothalamus. It is synthesized from the precursor protein prepro-orexin in neurons. Orexin A binds to its G-protein-coupled receptor orexin-1 (OX1) which is also called as hcrt receptors 1 (hcrtr1).
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.
