190 research outputs found

    The orexin system: Roles in sleep/wake regulation

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    金沢大学医薬保健研究域医学系The neuropeptides orexin A and orexin B, produced in hypothalamic neurons, are critical regulators of sleep/wake states. Deficiency of orexin signaling results in narcoleptic phenotype in humans, dogs, and rodents. Recently, accumulating evidence has indicated that the orexin system regulates sleep and wakefulness through interactions with neuronal systems that are closely related with emotion, reward, and energy homeostasis. In this review, we will discuss the current understanding of the physiology of the orexin system especially focusing on its roles in the regulation of sleep/wakefulness states. © 2010 New York Academy of Sciences

    Effect of Hemodialysis on Plasma Glucose Profile and Plasma Level of Liraglutide in Patients with Type 2 Diabetes Mellitus and End-Stage Renal Disease: A Pilot Study

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    The effect of hemodialysis on the plasma glucose profile and liraglutide level after liraglutide injection was investigated in patients with diabetes and end-stage renal disease (ESRD). Either 0.6 mg or 0.9 mg liraglutide was subcutaneously administered daily to 10 Japanese type 2 diabetic patients with ESRD. Hemodialysis was conducted on days 1 and 3. Plasma liraglutide and glucose concentrations were measured by enzyme-linked immunosorbent assay and a continuous glucose monitoring system, respectively. The safety profile of liraglutide was also assessed. Hemodialysis had no effect on the pharmacokinetic parameters of liraglutide in patients with diabetes and ESRD; the maximum plasma concentration (Cmax), tmax, area under the concentration-time curve (AUC), and CL/f were unaltered. Similarly, hemodialysis did not affect the mean or minimum glucose levels, AUC, or duration of hyperglycemia (>180 mg/dL) and hypoglycemia (<70 mg/dL) following liraglutide administration. However, significant increases in mean amplitude of glycemic excursions (MAGE) and standard deviation (SD) as markers of glucose fluctuation, and the maximum glucose level were observed during hemodialysis. No adverse events, including hypoglycemia, were observed after liraglutide injection, either off-hemodialysis (day 2) or on-hemodialysis (day 3). Liraglutide was well tolerated in patients with type 2 diabetes and ESRD undergoing hemodialysis. The present results suggested that hemodialysis did not affect the pharmacokinetic profile of liraglutide or most glycemic indices, with the exception of MAGE, SD, and the maximum glucose level. These results suggested that it may be possible to use liraglutide during hemodialysis for diabetes with ESRD, without dose adjustment. Trial Registration UMIN Clinical Trials Registry (UMIN-CTR) UMIN000010159.\ud \u

    Activation of Bombesin receptor subtype-3 influences activity of orexin neurons by both direct and indirect pathways

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    金沢大学医薬保健研究域医学系The neuropeptides orexin A and orexin B (also known as hypocretin 1 and hypocretin 2), produced in lateral hypothalamic neurons, are critical regulators of feeding behavior, the reward system, and sleep/wake states. Orexin-producing neurons (orexin neurons) are regulated by various factors involved in regulation of energy homeostasis and sleep/wakefulness states. Bombesin receptor subtype 3 (BRS3) is an orphan receptor that might be implicated in energy homeostasis and is highly expressed in the hypothalamus. However, the neural pathway by which BRS3 regulates energy homeostasis is largely unknown. We examined whether BRS3 is involved in the regulation of orexin neurons. Using a calcium imaging method, we found that a selective BRS3 agonist [Ac-Phe-Trp-Ala-His-(τBzl)-Nip-Gly-Arg-NH2] increased the intracellular calcium concentration of orexin neurons. However, intracellular recordings from slice preparations revealed that the BRS3 agonist hyperpolarized orexin neurons. The BRS3 agonist depolarized orexin neuron in the presence of tetrodotoxin. Moreover, in the presence of GABA receptor blockers, picrotoxin and CGP55845, the BRS3 agonist induced depolarization and increased firing frequency. Additionally, double-label in situ hybridization study revealed that Brs3 mRNA was expressed in almost all orexin neurons and many cells around these neurons. These findings suggest that the BRS3 agonist indirectly inhibited orexin neurons through GABAergic input and directly activated orexin neurons. Inhibition of activity of orexin neurons through BRS3 might be an important pathway for regulation of feeding and sleep/wake states. This pathway might serve as a novel target for the treatment of obesity. © 2010 Springer Science+Business Media, LLC

    Serotonergic Input to Orexin Neurons Plays a Role in Maintaining Wakefulness and REM Sleep Architecture

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    Neurons expressing neuropeptide orexins (hypocretins) in the lateral hypothalamus (LH) and serotonergic neurons in the dorsal raphe nucleus (DR) both play important roles in the regulation of sleep/wakefulness states, and show similar firing patterns across sleep/wakefulness states. Orexin neurons send excitatory projections to serotonergic neurons in the DR, which express both subtypes of orexin receptors (Mieda et al., 2011), while serotonin (5-HT) potently inhibits orexin neurons through activation of 5HT1A receptors (5HT1ARs). In this study, we examined the physiological importance of serotonergic inhibitory regulation of orexin neurons by studying the phenotypes of mice lacking the 5HT1A receptor gene (Htr1a) specifically in orexin neurons (ox5HT1ARKO mice). ox5HT1ARKO mice exhibited longer NREM sleep time along with decreased wakefulness time in the later phase of the dark period. We also found that restraint stress induced a larger impact on REM sleep architecture in ox5HT1ARKO mice than in controls, with a larger delayed increase in REM sleep amount as compared with that in controls, indicating abnormality of REM sleep homeostasis in the mutants. These results suggest that 5HT1ARs in orexin neurons are essential in the regulation of sleep/wakefulness states, and that serotonergic regulation of orexin neurons plays a crucial role in the appropriate control of orexinergic tone to maintain normal sleep/wake architecture

    Effects of a newly developed potent orexin-2 receptor-selective antagonist, compound 1 m, on sleep/wakefulness states in mice

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    Orexins (also known as hypocretins) play critical roles in the regulation of sleep/wakefulness states by activating two G-protein coupled receptors (GPCRs), orexin 1 (OX1R) and orexin 2 receptors (OX2R). In order to understand the differential contribution of both receptors in regulating sleep/wakefulness states we compared the pharmacological effects of a newly developed OX2R antagonist (2-SORA), Compound 1 m (C1 m), with those of a dual orexin receptor antagonist (DORA), suvorexant, in C57BL/6J mice. After oral administration in the dark period, both C1m and suvorexant decreased wakefulness time with similar efficacy in a dose-dependent manner. While C1m primarily increased total non-rapid eye movement (NREM) sleep time without affecting episode durations and with minimal effects on REM sleep, suvorexant increased both total NREM and REM sleep time and episode durations with predominant effects on REM sleep. Fos-immunostaining showed that both compounds affected the activities of arousal-related neurons with different patterns. The number of Fos-IR noradrenergic neurons in the locus coeruleus was lower in the suvorexant group as compared with the control and C1m-treated groups. In contrast, the numbers of Fos-IR neurons in histaminergic neurons in the tuberomamillary nucleus and serotonergic neurons in the dorsal raphe were reduced to a similar extent in the suvorexant and C1m groups as compared with the vehicle-treated group. Together, these results suggest that an orexin-mediated suppression of REM sleep via potential activation of OX1Rs in the locus coeruleus may possibly contribute to the differential effects on sleep/wakefulness exerted by a DORA as compared to a 2-SORA. © 2014 Etori, Saito, Tsujino and Sakurai

    Significance of the direct correlation of ammonite and radiolarian zones in the Izumi Group for integrated biostratigraphy of Late Cretaceous NW paleo-Pacific region

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    The direct correlation of radiolarian and ammonite zones in the Izumi Group were reviewed and revised for integrated biostratigraphy across the Campanian – Maastrichtian boundary. The significance of the direct correlation between mega- and micro-, i.e. between relatively near-shore nektonic and slope-basin planktonic faunas in the same stratigraphic field, was discussed in relation with the litho- and biofacies of the group. The Late Cretaceous ocean climate change and surface seawater current inferred from the radiolarian fauna was considered as a marker event for the chronostratigraphic correlation in the middle latitude continental shelf to slope-basin facies facing towards the NW paleo-Pacific

    シコク トウブ ナンブ クロセガワタイ サカシュウタイ ノ クリサカソウ トドロ セクション ニオケル ジュラキ コウキ ホウサンチュウ ソウジョ ト アンモナイト ネンダイ

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    The LAD (last appearance datum) of the radiolarian Kilinora spiralis (Matsuoka,1983) is found to concur with the FAD (first appearance datum)of the ammonite Ataxioceras (Ataxioceras) kurisakense Kobayashi and Fukada,1947 in the Todoro Section of the Kurisaka Formation,Southen Kurosegawa Terrane (Sakashu Belt), Shikoku,SW Japan. Providing a clue to the still pending chronological discrepancy between European and North American radiolarian zones,the constraint by ammonite age prolongs the range of the Kilinora spiralis Zone,a remarkable Upper Jurassic radiolarian zone in Japan -NW Pacific region,into the Lower Kimmeridgian
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