Description_x000D_ Amino Acid Sequence_x000D_ Glp-Pro-Leu-Pro-Asp-Cys-Cys-Arg-Gln-Lys-Thr-Cys-Ser-Cys-Arg-Leu-Tyr-Glu-Leu-Leu-His-Gly-Ala-Gly-Asn-His-Ala-Ala-Gly-Ile-Leu-Thr-Leu-NH2 [Disulfide Bridges: 6-12; 7-14]_x000D_ General description_x000D_ Orexin A is characterized with an N-terminal pyroglutamyl residue, two intramolecular disulfide bridges and a C-terminal amidation._x000D_ 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)._x000D_ Application_x000D_ 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)._x000D_ Orexin A human, rat, mouse has been used to study its effect on the functioning of porcine pancreatic islets. It has also been used as an orexin receptor 1 (OX1R) antagonist to study the effect of orexin systems in the effect of etonogestrel on respiratory response to prolonged metabolic acidosis._x000D_ Biochem/physiol Actions_x000D_ 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._x000D_ Orexins plays a vital role in several physiological functions including feeding, neuroendocrine regulation and arousal. In addition to this, it is also associated with the pathophysiology of narcolepsy. Orexin A, expressed in locus coeruleus (LC) area, binds to orexin-1 (OX1) receptor and regulates rapid eye movement (REM) sleep by acting on the firing rate of noradrenergic neurons. Orexin A release is regulated by suprachiasmatic nucleus (SCN)._x000D_ Other Notes_x000D_ Lyophilized from 0.1% TFA in H2O