Orexin B
Hypocretin-2
The wakefulness signal's sibling.
Half-life
~ short
Mol. weight
2918.4 g/mol (approx, linear)
Sequence
28-amino-acid neuropeptide (linear, no disulfide bonds)
Discussions
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Overview
The second of the two orexin/hypocretin neuropeptides, sharing the same hypothalamic origin and wakefulness-regulating role as Orexin A but with distinct receptor selectivity — preferentially activating the orexin-2 (OX2R) receptor. It is studied alongside Orexin A to dissect how the two peptides divide the arousal-control workload.
Mechanism of action
Orexin B is derived from the same prepro-orexin precursor as Orexin A and signals through the same family of receptors, but with a preference for the orexin-2 (OX2R) receptor (whereas Orexin A is relatively non-selective). The OX2R pathway is particularly implicated in sleep-wake stabilization and narcolepsy pathophysiology. Studying the two peptides together lets researchers separate the arousal components each receptor mediates.
Researched benefits
- Co-regulates wakefulness alongside Orexin A
- OX2R-selective — linked to sleep-wake stabilization
- Useful for dissecting orexin receptor subtypes
Considerations
- Short half-life; poor blood-brain barrier penetration
- Not approved for human use
- Cardiovascular and arousal considerations
Key Academic Literature & Studies
Search more in PubMedPeer-reviewed citations and clinical trials evaluating Orexin B in scientific literature.
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View Orexin B index on PubMed (NCBI)