Orexins (also named hypocretins) are recently discovered neuropeptides made exclusively in the hypothalamus. Recent studies have shown that orexin cells located specifically in lateral hypothalamus (LH) are involved in motivated behavior for drugs of abuse as well as natural rewards. Administration of orexin has been shown to stimulate food consumption, and orexin signaling in VTA has been impl...

Orexin/hypocretin peptide mutations are rare in humans. Even though human narcolepsy is associated with orexin deficiency, this is only extremely rarely due to mutations in the gene coding prepro-orexin, the precursor for both orexin peptides. In contrast, coding and non-coding variants of the OX1 and OX2 orexin receptors have been identified in many human populations; sometimes, these have bee...

Orexin A and B are multifunctional neuropeptides that are involved in the regulation of food intake, energy metabolism, glucose regulation and wakefulness. They signal through two G-protein‑coupled receptors (GPCR): orexin receptor 1 (OX1R) and orexin receptor 2 (OX2R). Previous studies have shown that orexins interact with PI3K/AKT signaling pathways through OX1R-coupling in other cell types, ...

We used an ABA renewal design to study the neural correlates, and role of D1 dopamine receptors, in contextual control over extinguished alcohol-seeking. Rats were trained to respond for 4% beer in one context (A), extinguished in a different (B) context, and then tested for responding in the original training context (A) or the extinction context (B). ABA renewal was mediated by D1 dopamine re...

Accessible online at: www.karger.com/res Research in both obesity and sleep has blossomed in the past decade. The close association between obesity and the obstructive sleep apnea syndrome has led to the idea that weight and sleep have common regulatory elements. Leptin, interleukin-6 and tumor necrosis factor-· are all increased in the plasma of middle-aged men with obstructive sleep apnea [1]...

Orexins are two recently discovered neuropeptides that can stimulate food intake. As the chronic use of tobacco typically leads to a reduction in body weight, it is of interest to determine whether nicotine, the major biologically active tobacco ingredient, has an effect on orexin metabolism in the brain. Using a semiquantitative RT-PCR technique, the levels of messenger RNA (mRNA) for prepro-o...

Orexins, which were initially identified as endogenous peptide ligands for two orphan G-protein coupled receptors (GPCRs), have been shown to have an important role in the regulation of energy homeostasis. Furthermore, the discovery of orexin deficiency in narcolepsy patients indicated that orexins are highly important factors for the sleep/wakefulness regulation. The efferent and afferent syst...

Dorsal raphe serotonin neurons fire tonically at a low rate during waking. In vitro, however, they are not spontaneously active, indicating that afferent inputs are necessary for tonic firing. Agonists of three arousal-related systems impinging on the dorsal raphe (orexin/hypocretin, histamine and the noradrenaline systems) caused an inward current and increase in current noise in whole-cell pa...

The number of hypothalamic neuropeptides that have been implicated in the regulation of feeding has grown steadily over recent years (Inui, 1999). Many of these reduce food intake but some increase it. These are neuropeptide Y, Agouti-related protein (a natural antagonist of the melanocortin-4 receptor), melanin-concentrating hormone, galanin and the orexins. Neuropeptide Y and Agouti-related p...