Orexin B, Human

Like orexin A, orexin B is a hypothalamic neuropeptide regulating the feeding behavior. Central administration of orexin B to rats stimulated food consumption in a similar manner to orexin A, but the effect did not last as long as that of orexin A. The affinity of orexin B for the OX? receptor is significantly lower (IC?? = 240 nM) than that of orexin A. Binding affinities for the OX? receptor are similar for orexin A and B (IC?? = 38 nM and 36 nM, respectively, for displacement of radiolabeled orexin A bound to the receptor).