STUDY OBJECTIVE Orexin-A is hypothesized to promote wakefulness, and we examined whether cerebrospinal fluid (CSF) orexin-A levels are higher during the waking period in man. DESIGN Within-subjects, repeated-measures design with balanced ordering of sampling at approximately 5 AM and 5 PM. PARTICIPANTS Eight healthy young males. MESUREMENTS: CSF orexin-A levels and standard polysomnography....

Orexin-A and orexin-B are neuropeptides originally identified as endogenous ligands for two orphan G-protein-coupled receptors. Orexin neuropeptides (also known as hypocretins) are produced by a small group of neurons in the lateral hypothalamic and perifornical areas, a region classically implicated in the control of mammalian feeding behavior. Orexin neurons project throughout the central ner...

Falls in blood glucose induce hunger and initiate feeding. The lateral hypothalamic area (LHA) contains glucose-sensitive neurons (GSNs) and orexin neurons, both of which are stimulated by falling blood glucose and are implicated in hypoglycemia-induced feeding. We combined intracellular electrophysiological recording with fluorescein labeling of GSNs to determine their neuroanatomic and functi...

A central neuronal network that regulates respiration may include hypothalamic neurons that produce orexin, a peptide that influences sleep and arousal. In these experiments, we investigated 1) projections of orexin-containing neurons to the pre-Botzinger region of the rostral ventrolateral medulla that regulates rhythmic breathing and to phrenic motoneurons that innervate the diaphragm; 2) the...

Orexin is a hypothalamic neuropeptide that regulates feeding behavior in rats. Orexin-B has recently been cloned in pigs and was shown to stimulate food intake after intramuscular injection. This study was designed to determine whether intracerebroventricular (ICV) and intravenous injections of orexin could regulate appetite in sheep. Suffolk wethers were moved to indoor facilities, adapted to ...

STUDY OBJECTIVES Orexin and orexin receptors are present in the CNS. The effects of orexin peptides have been uniformly reported as excitatory, and the posterior hypothalamus containing orexin neurons has been implicated in arousal state control. Therefore, it is probable that the orexin system may have a neuromodulatory effect on arousal states. The aim of the present study was to investigate ...

objective: it is well known that intracerebroventricular (icv) and supraspinal injections of orexin-a elicit analgesia, but the mechanism(s) of action remains unidentified. this study aims to characterize the effect of orexin-a on rostral ventromedial medulla (rvm) neurons which are involved in the descending nociception modulating pathway. materials and methods: in this experimental study, we ...

BACKGROUND Recent studies suggest that the novel neuropeptide orexin-A may play an essential role during neuronal damage. However, the function of orexin-A during brain ischemia remains unclear. Recently, hypoxia-inducible factor-1α (HIF-1α) was shown to be activated by orexin-A. The aim of the current study is to test the hypothesis that administration of exogenous orexin-A can attenuate ische...

Orexin A stimulates GnRH release from hypothalamic explants in vitro. The sites of action of orexin A in the regulation of LH release have been investigated in vivo in ovariectomized rats that were given vehicle or estradiol benzoate (EB), with or without an injection of progesterone 48 h later. Orexin A was administered intrahypothalamically under Saffan anesthesia, 50 h after the EB or vehicl...

Orexinergic system may play an important role in the regulation of anesthesia-arousal. However, which region or which pathway mediated the effect of orexins was still unclear. In current study, we investigated whether activation of orexin signals in basal forebrain (BF) may alter electroencephalographic activity, induction and emergence time to sevoflurane anesthesia in rats. Either orexin-A or...