Orexin neuropeptides promote arousal, appetite, reward, and energy expenditure. However, whether orexin affects bone mass accrual is unknown. Here, we show that orexin functions centrally through orexin receptor 2 (OX2R) in the brain to enhance bone formation. OX2R null mice exhibit low bone mass owing to elevated circulating leptin, whereas central administration of an OX2R-selective agonist a...

Orexin receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on [43]) are activated endogenous polypeptides orexin-A and orexin-B (also known hypocretin-1 -2; 33 28 aa) derived from a common precursor, preproorexin or orexin proteolytic cleavage some typical peptide modifications [117]. signaling has been associated with regulation of sleep wakefulness, reward addiction, appetite feed...

Hypocretins (orexins) are recently discovered hypothalamic neuropeptides that have been implicated in the etiology of narcolepsy. The normal behavioral functions of these peptides are unclear, although a role in feeding has been suggested. We measured hypocretin-1 (Hcrt-1) in the cerebrospinal fluid of dogs during a variety of behaviors. We found that 48 h without food (24 h beyond normal 24-h ...

Orexin is produced exclusively in the lateral hypothalamus, where it is known to be involved in pain modulation through brain stem. Due to the important role of this peptide in functions such as eating, sleeping and awaking, addiction, it attracted the attention of researchers in medical sciences specially neuroscientists. These hypothalamic peptides play a critical role in arousal in s...

Orexin neurons (hypocretin neurons) have a critical role in the regulation of sleep/wakefulness, especially in the maintenance of arousal. Here, we revealed that orexin neurons are directly and indirectly activated by orexin via the orexin 2 receptor (OX2R). Orexin B (1 μM) induced depolarization in orexin neurons, which was still observed in the presence of TTX (1 μM), AP-5 (50 μM), and CNQX (...

Orexin/hypocretin neurons have a crucial role in the regulation of sleep and wakefulness. To help determine how these neurons promote wakefulness, we generated transgenic mice in which orexin neurons expressed halorhodopsin (orexin/Halo mice), an orange light-activated neuronal silencer. Slice patch-clamp recordings of orexin neurons that expressed halorhodopsin demonstrated that orange light p...

The neuropeptides, orexin-A and orexin-B, have been demonstrated to have a physiological role in the regulation of food intake in mammals. The effects of human orexin-A and orexin-B intracerebroventricular (i.c.v.) injection on the feeding behavior of goldfish (Carassius auratus) were investigated. I.c.v. injection of orexin-A and orexin-B both caused a significant increase in appetite, as indi...

Orexin A and B (hypocretin 1 and 2) are the endogenous ligands of orexin receptors, a G-protein-coupled orphan receptor family containing orexin 1 (OX1) and orexin 2 (OX2) types. Orexin A induces analgesia in acute and inflammatory pain models. We further elucidated the possible antiallodynic effect of intrathecal orexins in a rat model of postoperative pain. Mechanical allodynia was induced by...

It has long been established that histamine plays a role as a mediator of inflammation. From numerous studies, it has been well known that the amine has many pharmacological actions on a variety of organs. To evaluate the role of histamine in pain perception, we generated HDC knockout mice using a gene targeting method. Histamine is a hydrophilic autacoid, and in most tissues it is stored and s...