Orexin

Thank you for visiting nature. You are using a browser version with limited support for CSS, orexin.

Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Humans and animals lacking orexin neurons exhibit daytime sleepiness, sleep attacks, and state instability. While the circuit basis by which orexin neurons contribute to consolidated wakefulness remains unclear, existing models posit that orexin neurons provide their wake-stabilizing influence by exerting excitatory tone on other brain arousal nodes. Here we show using in vivo optogenetics, in vitro optogenetic-based circuit mapping, and single-cell transcriptomics that orexin neurons also contribute to arousal maintenance through indirect inhibition of sleep-promoting neurons of the ventrolateral preoptic nucleus.

Orexin

Orexins, also known as hypocretins, are two neuropeptides secreted from orexin-containing neurons, mainly in the lateral hypothalamus LH. The orexins, also known as hypocretins, are a pair of neuropeptides that are mainly derived from orexin-containing neurons in the lateral hypothalamus LH. Orexin-A OA; hypocretin-1 and orexin-B OB; hypocretin-2 are closely related small peptides that are widely distributed throughout the central and peripheral nervous systems de Lecea et al. Orexins stimulate food intake upon intracerebroventricular administration, and were originally described as regulators of feeding behavior Yamanaka et al. Subsequent experiments revealed many other important physiological functions of these peptides, including regulation of the sleep—wake cycle de Lecea and Sutcliffe, ; Chow and Cao, , energy homeostasis Tsuneki et al. Orexins bind their cognate G-protein—coupled receptors GPCRs , orexin receptor type 1 OX1R, also named as Hcrtr-1 and type 2 OX2R, or Hcrtr-2 , which activate different downstream signal pathways, thereby exerting a variety of physiological functions Sakurai et al. Orexin and orexin receptors are ectopically expressed in many diseases Perez et al. In this review article, we focus on the expression levels and physiological functions of orexins and their receptors. In , two experimental groups nearly simultaneously discovered a pair of new neuropeptides in the LH and adjacent areas of rat brain. One group de Lecea et al. On the other hand, Sakurai et al. The structure of the orexin gene, which consists of two exons and one intron, is conserved in all vertebrates.

Peyron, C.

Orexin neurons receive a variety of signals related to environmental, physiological and emotional stimuli, and project broadly to the entire CNS. Furthermore, a dysfunction of orexinergic system may underlie different pathological conditions. A selective loss orexin neurons was found in narcolepsia, supporting the crucial role of orexins in maintaining wakefulness. In animal models, orexin deficiency lead to obesity even if the consume of calories is lower than wildtype counterpart. Reduced physical activity appears the main cause of weight gain in these models resulting in energy imbalance. Interestingly, orexinergic neurons show connections to regions involved in cognition and mood regulation, including hippocampus. Orexins enhance hippocampal neurogenesis and improve spatial learning and memory abilities, and mood.

Federal government websites often end in. The site is secure. Preview improvements coming to the PMC website in October Learn More or Try it out now. Orexins, also known as hypocretins, are two neuropeptides secreted from orexin-containing neurons, mainly in the lateral hypothalamus LH.

Orexin

The most common form of narcolepsy , type 1, in which the individual experiences brief losses of muscle tone "drop attacks" or cataplexy , is caused by a lack of orexin in the brain due to destruction of the cells that produce it. There are 50,—80, orexin-producing neurons in the human brain, [8] located predominantly in the perifornical area and lateral hypothalamus. Orexin was discovered in almost simultaneously by two independent groups of researchers working on the rat brain. Luis de Lecea, Thomas Kilduff , and colleagues reported the discovery of the hypocretin system at the same time as Takeshi Sakurai from Masashi Yanagisawa 's lab at the University of Texas Southwestern Medical Center at Dallas reported the discovery of the orexins to reflect the orexigenic appetite-stimulating activity of these peptides. In their paper describing these neuropeptides, they also reported discovery of two orexin receptors, dubbed OX 1 R and OX 2 R. The two groups also took different approaches towards their discovery.

What happened to clarence gilyard from walker texas ranger

Orexin signaling in recombinant neuron-like cells. Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior. Sutcliffe JG. This intra-VLPO circuit mechanism for promoting state transitions could be shared by most, if not all, wake- and sleep-promoting afferences that modulate VLPO activity 32 , 34 , 35 , 36 , Barson, J. Harris, G. In animal models, orexin deficiency lead to obesity even if the consume of calories is lower than wildtype counterpart. In humans, narcolepsy is associated with a specific variant of the human leukocyte antigen HLA complex. Basal forebrain control of wakefulness and cortical rhythms. The hypocretin-orexin system regulates cocaine self-administration via actions on the mesolimbic dopamine system. January

.

Huang, S. Progress in Brain Research. The European Journal of Neuroscience. Escalated or suppressed cocaine reward, tegmental BDNF and accumbal dopamine caused by episodic versus continuous social stress in rats. Cell 98, — In addition, Hcrtr2 mRNA was expressed in The abovementioned parameters were also applied to this function. These include all individual data points and average values showed in both figures and supplementary information. Kastin, A. Charney DS. Correctly targeted ES cells were identified and then injected into blastocysts to generate chimeras.