OREXIN B (HUMAN)

Orexin B is a hypothalamic neuropeptide that regulates feeding behavior, wakefulness, and behavior under situations of high motivational relevance. It is an agonist of orexin (OX) receptors with IC₅₀ values of 420 and 36 nM for human recombinant OX₁ and OX₂ receptors, respectively, expressed in CHO cells. It induces transient increases in intracellular calcium in CHO cells stably expressing OX₁ and OX₂ (EC₅₀s = 2,500 and 60 nM, respectively) and in primary rat ventral tegmental area (VTA) dopaminergic neurons. Orexin B stimulates arachidonic acid release from CHO cells expressing human recombinant OX₁ (EC₅₀ = 4.17 nM). It also stimulates food intake in freely feeding mice and goldfish when administered at intracerebroventricular doses of 30 nmol and 10 ng/g, respectively.

Orexins/Hypocretins, Orexin A/ hypocretin-1 and Orexin B/ hypocretin-2, are excitatory neuropeptides that mediate there effects via two receptors, OX-1 and OX-2. Orexins are involved in food intake, obesity regulation, energy homeostasis and differentiation.