Orexin A (monkey) – Neuroscience Peptides

Orexin A is one of two closely related peptides- the orexins (also known as hypocretins). These small neuropeptides are secreted from orexin-containing neurons, located mainly in the lateral hypothalamus (LH). Orexins function via the binding and activation of two G-protein-coupled receptors (GPCRs)- orexin receptor type 1 (OX1R) and 2 (OX2R). Orexins play several vital roles in a range of physiological activities, including: circadian rhythm, feeding behaviour, energy balance, glucose metabolism, neuroendocrine functions, stress-adaptive responses and reward and addiction. Orexins have also been linked to the pathological processes of neurological diseases such as: narcolepsy- depression- ischemic stroke- drug addiction and Alzheimer’s disease. This Orexin A peptide contains two disulphide bridges, one between cysteine 7 and cysteine 13, and the other between cysteine 8 and 15. Orexin-A appears to be the isoform most important for the feeding response.