What is Orexin A??
Orexin A (Hypocretin-1, CAS 205599-75-3) is a 33-amino acid hypothalamic neuropeptide produced from prepro-orexin by enzymatic cleavage. It has an N-terminal pyroglutamyl residue, two intramolecular disulfide bridges (Cys6-Cys12, Cys7-Cys14), and C-terminal amidation. MW 3562.14 g/mol. Orexin A is produced exclusively in a small population (~50,000-80,000) of lateral hypothalamic neurons and projects widely through the CNS. It binds both OX1R and OX2R receptors (Gq-coupled) with approximately equal high affinity – activating arousal circuits involving norepinephrine (locus coeruleus), dopamine, histamine, and acetylcholine systems. Loss of orexin-producing neurons causes narcolepsy type 1 – the definitive disease model for the orexin system. Orexin A also modulates feeding behaviour, reward/motivation, stress responses, and energy homeostasis.
Research Applications
Sleep/Wake & Arousal Research
OX1R/OX2R-mediated wakefulness stabilisation, narcolepsy/cataplexy models, hypocretin neuron ablation studies
Narcolepsy Models
Orexin deficiency rescue in orexin knockout mice, ICV administration cognitive restoration in sleep-deprived primates
Appetite & Feeding Behaviour
Orexigenic signalling, lateral hypothalamic feeding circuits, NPY/orexin interaction, fasting-induced prepro-orexin upregulation
Reward & Addiction
OX1R role in drug-seeking, reward salience, cocaine/opioid cue-induced reinstatement models
Energy Homeostasis
Glucose-sensing orexin neurons, tandem pore K+ channel glucose inhibition, OX2R feeding and adiposity regulation
Quick Specs
| Form | Lyophilized powder |
| Purity | >=99% by HPLC – every batch |
| CAS Number | 205599-75-3 |
| Molecular Weight | MS molecular weight confirmed – every batch |
| Specification | >=99% by HPLC – every batch |
| Shelf Life | 24 months unopened |
| Storage | -20C sealed | 2-8C reconstituted (2-4 weeks) |
| Manufacture | In-house Fmoc SPPS – Qingdao, China |
| Brand | Asia |