Orexin A (human, rat, mouse)
(Synonyms: 促食素A,Hypocretin-1 (human, rat, mouse)) 目录号 : GC12522
Orexin A 人类、大鼠、小鼠，一种 33 个氨基酸的兴奋性神经肽，协调不同的中枢和外周过程。
Cas No.:205640-90-0
Sample solution is provided at 25 µL, 10mM.
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Quality Control & SDS
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- Purity: >98.00%
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- SDS (Safety Data Sheet)
- Datasheet
| Cell experiment [1]: | |
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Cell lines |
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Preparation Method |
Full-length cDNAs encoding individual orphan GPCRs were subcloned into the pCDN mammalian expression vector. These plasmids were individually transfected into the human embryonic kidney (HEK) 293 cells, and stable transfectant cell lines established and maintained. For in vitro pharmacological assessments , CHO-K1 cells were stably transfected with human OX1R and OX2R expression vectors, and transfected cell lines were maintained . |
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Reaction Conditions |
3 nmol /30 nmol |
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Applications |
The concentration of Orexin-A required to induce half-maximum response (EC50) was 30 nM. Obtained similar results in radioligand binding and [Ca2+]i transient assays performed with stably transfected HEK293 cells . Orexin A human, rat, mouse has high affinity for OX1R, with 38 nM IC50 and 34 nM EC50 values in the the [Ca2+]i transient assay. |
| Animal experiment [2]: | |
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Animal models |
C57BL/6J mice and OX1R+/+, OX1R-/-, OX2R+/+, OX2R-/- and OX1R-/-/OX2R-/- mice |
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Preparation Method |
Orexin A was injected by intracerebroventricular (ICV): the mice were gently restrained , injectors with a diameter of 0.15 mm (connected to Hamilton syringes by tubes) were introduced into the guide cannulae, and the animals were released in a cage. A total volume of 0.3 µl solution with 3 µg orexin A was then injected at a flow rate of 0.1 µl/min, controlled by a microinfusion pump. |
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Dosage form |
0.3 µl solution with 3 µg orexin A /0.1 µl/min |
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Applications |
Orexin A is inhibited by almorexant specifically. The two known orexin receptors mediate sleep induction by almorexant and orexin A-induced locomotion. However, OX2R activation mediates locomotion induction by orexin A and antagonism of OX2R is sufficient to promote sleep in mice. |
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References: [1]. Sakurai T, et al. Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior. Cell. 1998 Feb 20;92(4):573-85. | |
Orexin A (human, rat, mouse), orchestrates diverse central and peripheral processes[1]. Orexin A (human, rat, mouse) is a specific, high-affinity agonist for G-protein-coupled receptor OX1R. Orexin A (human, rat, mouse) has a role in the regulation of feeding behavior. Orexin A (human, rat, mouse) is an effective anti-nociceptive and anti-hyperalgesic agent in mice and rats[2].Orexins first bind OXRs, which in turn activate at least three subtypes of G-proteins (Gq/11, Gi/o, and Gs) or other proteins (e.g., β-arrestin). These effectors subsequently regulate phospholipases, ion channels, and protein kinases, ultimately triggering the activation of various downstream signaling pathways [3,5].
Orexin-A induced a transient increase in [Ca2+ ]i in CHO/OX1R cells in a dose-dependent manner, but failed to induce detectable [Ca2+ ]i transients in mock transfected CHO cells. The calcium mobilization is likely caused by the activation of the Gq class of heterotrimeric G proteins[6].The calculated concentration of orexin-A required to induce half-maximum response (EC50 ) was 30 nM. The concentration of unlabeled Orexin-A required to displace 50% of specific radioligand binding (IC50 ) was 20 nM. Repeated competitive radioligand binding assays and [Ca2+ ]i transient dose-response studies using stably transfected CHO cells expressing the human OX2R cDNA. The results demonstrated that OX2R is indeed a high-affinity receptor for human orexin-B, with an IC50 of 36 nM in the binding assay and an EC50 of 60 nM in the [Ca2+ ]i transient assay . Orexin-A had high affinity for this receptor, with 38 nM IC50 and 34 nM EC50 values.These findings confirm that orexin-A is indeed a specific, high-affinity agonist for OX1R.
The Orexin A concentration in cerebrospinal fluid (CSF) was abnormally low in seven of nine people with narcolepsy, implying that orexin transmission was deficient in these patients[7].In a later study, the same group reported a dramatic decrease in the CSF Orexin A levels in 32 of 38 successive narcolepsy-cataplexy cases [8].On the basis of these findings, they concluded that Orexin is deficient in most cases of human narcolepsy, suggesting possible diagnostic applications. Furthermore, the number of orexin neurons is reduced by 85%-95% in the LH of patients with narcolepsy [9]. Orexin mRNA and neuropeptide are completely absent in hypothalamus, pons and cortex of narcolepsy patients, and the secretory signal sequence of the orexin gene is deficient in the most serious cases of early onset narcolepsy [10].These observations further prove that narcolepsy is associated with deficiency in the orexin system.
The binding of orexins to orexin receptor type 1 (OX1R) or OX2R stimulates Gq or Gi subtypes, which subsequently induce the activation of phospholipase C (PLC), phospholipase A (PLA), phospholipase D (PLD) or Adenylyl cyclases (AC), ultimately resulting in an increase in cytosolic Ca2+ and a downstream cascade response. In addition, OA binds OX1R and elevates Ca2+ by activating nonselective cation channels (NSCCs) [11].
References:
[1]. Bingham S, et al. Orexin-A, an hypothalamic peptide with analgesic properties. Pain. 2001 May;92(1-2):81-90.
[2]. Sakurai T, et al. Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior. Cell. 1998 Feb 20;92(4):573-85.
[3].Dalrymple M B, Jaeger W C, Eidne K A, et al. Temporal profiling of orexin receptor-arrestin-ubiquitin complexes reveals differences between receptor subtypes[J]. Journal of Biological Chemistry, 2011, 286(19): 16726-16733.
[4].Kukkonen J P, Leonard C S. Orexin/hypocretin receptor signalling cascades[J]. British journal of pharmacology, 2014, 171(2): 314-331.
[5].Leonard C S, Kukkonen J P. Orexin/hypocretin receptor signalling: a functional perspective[J]. British journal of pharmacology, 2014, 171(2): 294-313.
[6].Hepler J R, Kozasa T, Gilman A G. [16] Purification of recombinant Gqα, G11α, and G16α from Sf9 cells[M]//Methods in enzymology. Academic Press, 1994, 237: 191-212.
[7].Nishino S, Ripley B, Overeem S, et al. Hypocretin (orexin) deficiency in human narcolepsy[J]. The Lancet, 2000, 355(9197): 39-40.
[8].Nishino S, Ripley B, Overeem S, et al. Low cerebrospinal fluid hypocretin (Orexin) and altered energy homeostasis in human narcolepsy[J]. Annals of Neurology: Official Journal of the American Neurological Association and the Child Neurology Society, 2001, 50(3): 381-388.
[9].Thannickal T C, Moore R Y, Nienhuis R, et al. Reduced number of hypocretin neurons in human narcolepsy[J]. Neuron, 2000, 27(3): 469-474.
[10].Peyron C, Faraco J, Rogers W, et al. A mutation in a case of early onset narcolepsy and a generalized absence of hypocretin peptides in human narcoleptic brains[J]. Nature medicine, 2000, 6(9): 991-997.
[11].Wang C, Wang Q, Ji B, et al. The orexin/receptor system: molecular mechanism and therapeutic potential for neurological diseases[J]. Frontiers in molecular neuroscience, 2018, 11: 220.
Orexin A（人类、大鼠、小鼠）协调不同的中枢和外周过程[1]。 Orexin A（人、大鼠、小鼠）是 G 蛋白偶联受体 OX1R 的特异性高亲和力激动剂。 Orexin A（人类、大鼠、小鼠）在调节摄食行为中发挥作用。食欲素 A（人、大鼠、小鼠）是小鼠和大鼠的有效抗伤害感受剂和抗痛觉过敏剂[2]。食欲素首先结合 OXRs，进而激活 G 的至少三种亚型-蛋白质（Gq/11、Gi/o 和 Gs）或其他蛋白质（例如，β-arrestin）。这些效应子随后调节磷脂酶、离子通道和蛋白激酶，最终触发各种下游信号通路的激活[3,5]。
Orexin-A 以剂量依赖性方式诱导 CHO/OX1R 细胞中 [Ca2+ ]i 的瞬时增加，但未能诱导可检测的 [Ca2+ ]i 模拟转染的 CHO 细胞中的瞬变。钙动员可能是由异源三聚体 G 蛋白的 Gq 类激活引起的[6]。计算的 orexin-A 诱导半数最大反应所需的浓度 (EC50) 为 30 nM。取代 50% 特定放射性配体结合所需的未标记 Orexin-A 浓度 (IC50 ) 为 20 nM。使用稳定转染的表达人 OX2R cDNA 的 CHO 细胞进行重复竞争性放射性配体结合测定和 [Ca2+ ]i 瞬时剂量反应研究。结果表明，OX2R 确实是人类 orexin-B 的高亲和力受体，结合试验中的 IC50 为 36 nM，EC50 为 60 nM在 [Ca2+ ]i 瞬时测定中。 Orexin-A 对该受体具有高亲和力，具有 38 nM IC50 和 34 nM EC50 值。这些发现证实 orexin-A 确实是一种特异性的、高- OX1R 的亲和激动剂。
9 名发作性睡病患者中有 7 人的脑脊液 (CSF) 中的食欲素 A 浓度异常低，这意味着这些患者的食欲素传递不足[7]。在后来的研究中，同一组报告称，连续 38 例嗜睡症-猝倒病例中有 32 例的 CSF Orexin A 水平显着下降[8]。根据这些发现，他们得出结论，Orexin A 水平在大多数人类病例中是缺乏的发作性睡病，提示可能的诊断应用。此外，发作性睡病患者 LH 中的食欲素神经元数量减少了 85%-95%[9]。发作性睡病患者的下丘脑、脑桥和皮质完全缺失食欲素 mRNA 和神经肽，并且在最严重的早发发作性睡病病例中食欲素基因的分泌信号序列缺失[10]。这些观察结果进一步证明发作性睡病与食欲素系统缺陷有关。
食欲素与食欲素受体 1 型 (OX1R) 或 OX2R 的结合刺激 Gq 或 Gi 亚型，随后诱导磷脂酶 C (PLC)、磷脂酶 A (PLA)、磷脂酶 D (PLD) 或腺苷酸环化酶 ( AC)，最终导致细胞溶质 Ca2+ 增加和下游级联反应。此外，OA 结合 OX1R 并通过激活非选择性阳离子通道 (NSCC) [11] 来升高 Ca2+。
| Cas No. | 205640-90-0 | SDF | |
| 别名 | 促食素A,Hypocretin-1 (human, rat, mouse) | ||
| Canonical SMILES | CC[C@]([C@@](/N=C(O)/C/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/C/N=C(O)/[C@](/N=C(O)/C/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O)/[C@](/N=C(O) | ||
| 分子式 | C152H247N47O44S4 | 分子量 | 3565.14 |
| 溶解度 | DMSO: 3 mg/ml,DMSO:PBS (pH 7.2) (1:1): 0.5 mg/ml | 储存条件 | Desiccate at -20°C |
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| 1 mM | 0.2805 mL | 1.4025 mL | 2.8049 mL |
| 5 mM | 0.0561 mL | 0.2805 mL | 0.561 mL |
| 10 mM | 0.028 mL | 0.1402 mL | 0.2805 mL |
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Role of Orexin-A in Hypertension and Obesity
Curr Hypertens Rep2017 Apr;19(4):34.PMID: 28353077DOI: 10.1007/s11906-017-0729-y
Purpose of review: Hypertension is one of the most challenging health problems inducing cerebrovascular disease and high percentage of death when associated with diabetes, dyslipidemias, and obesity. Orexin/hypocretin is a peptide expressed by a small number of neurons of the dorsolateral hypothalamus, a brain feeding and autonomic "fight-or-flight" regulatory center. According to this function, Orexin has been demonstrated to evoke cardiovascular responses, heart rate, hypertension, hyperarousal, hyperphagia, and obesity. The focus of this review is to provide an overview about the mechanism through which Orexin regulates food intake and cardiovascular responses and its role in the pathogenesis of obesity and hypertension which could be of great interest to establish possible new therapies.
Recent findings: In normal rats and mice, central administration of Orexin increases food intake, blood pressure, and sympathetic nerve activity and these effects are blocked by selective Orexin receptor antagonist SB-334867 or almorexant. Moreover, upregulation of Orexin signaling, in combination with elevation of epinephrine and norepinephrine circulating levels, occurs in rats exposed to chronic stress, in models of spontaneous hypertension (SHR and BPH/2J Schlager mice) and in obese mice (ob/ob or mice fed with high fat diet). Therefore, hyperactivity of Orexinergic neurons could be a factor in the development of obesity and essential hypertension. Because of their widespread projections to the brain regions involved in appetite and cardiovascular responses, as far down as sympathetic preganglionic neurons in the spinal cord, Orexin evokes sympathetically mediated cardiovascular responses. Lasting upregulation of Orexin signaling can lead to hyperphagia, obesity, and hypertensive state. Dual Orexin receptor antagonists (DORAs) and selective Orexin receptor antagonists (SORAs) have antihypertensive effects that could be of clinical use for regulation of food intake and hypertension, supporting the role of Orexinergic neurons as critical checkpoint in the neurogenic control of metabolic and cardiovascular functions.
The Orexin System and Hypertension
Cell Mol Neurobiol2018 Mar;38(2):385-391.PMID: 28349223DOI: 10.1007/s10571-017-0487-z
In this review, we focus on the role of Orexin signaling in blood pressure control and its potential link to hypertension by summarizing evidence from several experimental animal models of hypertension. Studies using the spontaneously hypertensive rat (SHR) animal model of human essential hypertension show that pharmacological blockade of Orexin receptors reduces blood pressure in SHRs but not in Wistar-Kyoto rats. In addition, increased activity of the Orexin system contributes to elevated blood pressure and sympathetic nerve activity (SNA) in dark-active period Schlager hypertensive (BPH/2J) mice, another genetic model of neurogenic hypertension. Similar to these two models, Sprague-Dawley rats with stress-induced hypertension display an overactive central Orexin system. Furthermore, upregulation of the Orexin receptor 1 increases firing of hypothalamic paraventricular nucleus neurons, augments SNA, and contributes to hypertension in the obese Zucker rat, an animal model of obesity-related hypertension. Finally, we propose a hypothesis for the implication of the Orexin system in salt-sensitive hypertension. All of this evidence, coupled with the important role of elevated SNA in increasing blood pressure, strongly suggests that hyperactivity of the Orexin system contributes to hypertension.
Orexin signaling modulates synchronized excitation in the sublaterodorsal tegmental nucleus to stabilize REM sleep
Nat Commun2020 Jul 21;11(1):3661.PMID: 32694504DOI: 10.1038/s41467-020-17401-3
The relationship between Orexin/hypocretin and rapid eye movement (REM) sleep remains elusive. Here, we find that a proportion of Orexin neurons project to the sublaterodorsal tegmental nucleus (SLD) and exhibit REM sleep-related activation. In SLD, Orexin directly excites Orexin receptor-positive neurons (occupying ~3/4 of total-population) and increases gap junction conductance among neurons. Their interaction spreads the Orexin-elicited partial-excitation to activate SLD network globally. Besides, the activated SLD network exhibits increased probability of synchronized firings. This synchronized excitation promotes the correspondence between SLD and its downstream target to enhance SLD output. Using optogenetics and fiber-photometry, we consequently find that Orexin-enhanced SLD output prolongs REM sleep episodes through consolidating brain state activation/muscle tone inhibition. After chemogenetic silencing of SLD Orexin signaling, a ~17% reduction of REM sleep amounts and disruptions of REM sleep muscle atonia are observed. These findings reveal a stabilization role of Orexin in REM sleep.
Orexin-A and endocannabinoids are involved in obesity-associated alteration of hippocampal neurogenesis, plasticity, and episodic memory in mice
Nat Commun2021 Oct 21;12(1):6137.PMID: 34675233DOI: 10.1038/s41467-021-26388-4
The mammalian brain stores and distinguishes among episodic memories, i.e. memories formed during the personal experience, through a mechanism of pattern separation computed in the hippocampal dentate gyrus. Decision-making for food-related behaviors, such as the choice and intake of food, might be affected in obese subjects by alterations in the retrieval of episodic memories. Adult neurogenesis in the dentate gyrus regulates the pattern separation. Several molecular factors affect adult neurogenesis and exert a critical role in the development and plasticity of newborn neurons. Orexin-A/hypocretin-1 and downstream endocannabinoid 2-arachidonoylglycerol signaling are altered in obese mice. Here, we show that excessive Orexin-A/2-arachidonoylglycerol/cannabinoid receptor type-1 signaling leads to the dysfunction of adult hippocampal neurogenesis and the subsequent inhibition of plasticity and impairment of pattern separation. By inhibiting Orexin-A action at Orexin-1 receptors we rescued both plasticity and pattern separation impairment in obese mice, thus providing a molecular and functional mechanism to explain alterations in episodic memory in obesity.
Pleasure, addiction, and hypocretin (Orexin)
Handb Clin Neurol2021;180:359-374.PMID: 34225941DOI: 10.1016/B978-0-12-820107-7.00022-7
The hypocretins/Orexins were discovered in 1998. Within 2 years, this led to the discovery of the cause of human narcolepsy, a 90% loss of hypothalamic neurons containing these peptides. Further work demonstrated that these neurons were not simply linked to waking. Rather these neurons were active during pleasurable behaviors in waking and were silenced by aversive stimulation. This was seen in wild-type mice, rats, cats, and dogs. It was also evident in humans, with increased Hcrt release during pleasurable activities and decreased release, to the levels seen in sleep, during pain. We found that human heroin addicts have, on average, an increase of 54% in the number of detectable Hcrt neurons compared to "control" human brains and that these Hcrt neurons are substantially smaller than those in control brains. We found that in mice, chronic morphine administration induced the same changes in Hcrt neuron number and size. Our studies in the mouse allowed us to determine the specificity, dose response relations, time course of the change in the number of Hcrt neurons, and that the increased number of Hcrt neurons after opiates was not due to neurogenesis. Furthermore, we found that it took a month or longer for these anatomical changes in the mouse brain to return to baseline. Human narcoleptics, despite their prescribed use of several commonly addictive drugs, do not show significant evidence of dose escalation or substance use disorder. Similarly, mice in which the peptide has been eliminated are resistant to addiction. These findings are consistent with the concept that an increased number of Hcrt neurons may underlie and maintain opioid or cocaine use disorders.