Orexin Receptors

The orexins (hypocretins) are a newly discovered family of neuropeptides which play a role in regulating feeding and wakefulness. The family currently consists of two members; orexin A and orexin B (33- and 28-residues respectively), which are produced from a common precursor prepro-orexin (130 amino acids). Cell bodies of orexin-containing neurons are largely confined to the lateral hypothalamus, an area classically linked to feeding stimulation. Intracerebroventricular injections of orexin A and orexin B stimulate feeding in a dose-related manner, with orexin A being significantly more effective than orexin B. Orexins are also strongly linked to the regulation of sleep-activity cycles, which may restrict the use of orexin ligands in the treatment of obesity. The orexins activate two G-protein-coupled receptors (OX1 and OX2) also found predominantly in the hypothalamus. Orexin A is the selective endogenous agonist for OX1 and blocking this receptor modulates food and water intake.

Orexin Receptor Target Files

Related Categories
Receptor Subtype OX1 Receptors OX2 Receptors
G protein Gq/11 Gq/11
Transduction Mechanism ↑ PLC → ↑ Ca2+ influx ↑ PLC → ↑ Ca2+ influx
Primary Locations Ventromedial hypothalamus, locus coeruleus, median raphe, hippocampus, tenia tecta Cerebral cortex (layers IV-VI), medial hypothalamus, paraventricular hypothalamus, nucleus accumbens, subthalamic and paraventricular thalamus, anterior pretectal nucleus
Likely Physiological Roles Sleep-wakefulness, energy homeostasis Sleep-wakefulness

Key Compounds Ki Values (nM)
Orexin A (human, rat, mouse) (1455) 20 38
Orexin B (human) (1456) 420 36
SB 334867 (1960) 7.2* < 5*
SB 408124 (1963) 21.7 1405
[Ala11,D-Leu15-Orexin B (2142) 52 0.13

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Peptide Hormone Receptors Product Listing

Peptide Hormone Receptors Product Listing

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Appetite Modulation

Written by S. Tucci et al

Peptides Involved in Appetite Modulation Scientific Review

Our Peptides Involved in Appetite Modulation review gives an overview of the peptides implicated in appetite regulation and energy homeostasis. View PDF today.

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