抗ヒスタミン薬ケトチフェンの連日投与による体内時計位相調節

富山大学・富生命博甲第90号・AHMAD ALSAWAF・2017/03/23Sleep and Biological Rhythms,2016.1,14(1),117-120,doi: 10.1007/s41105-015-0021-yに掲載。富山大学201

Phospholipase C-β4 Is Essential for the Progression of the Normal Sleep Sequence and Ultradian Body Temperature Rhythms in Mice

BACKGROUND: THE SLEEP SEQUENCE: i) non-REM sleep, ii) REM sleep, and iii) wakefulness, is stable and widely preserved in mammals, but the underlying mechanisms are unknown. It has been shown that this sequence is disrupted by sudden REM sleep onset during active wakefulness (i.e., narcolepsy) in orexin-deficient mutant animals. Phospholipase C (PLC) mediates the signaling of numerous metabotropic receptors, including orexin receptors. Among the several PLC subtypes, the beta4 subtype is uniquely localized in the geniculate nucleus of thalamus which is hypothesized to have a critical role in the transition and maintenance of sleep stages. In fact, we have reported irregular theta wave frequency during REM sleep in PLC-beta4-deficient mutant (PLC-beta4-/-) mice. Daily behavioral phenotypes and metabotropic receptors involved have not been analyzed in detail in PLC-beta4-/- mice, however. METHODOLOGY/PRINCIPAL FINDINGS: Therefore, we analyzed 24-h sleep electroencephalogram in PLC-beta4-/- mice. PLC-beta4-/- mice exhibited normal non-REM sleep both during the day and nighttime. PLC-beta4-/- mice, however, exhibited increased REM sleep during the night, their active period. Also, their sleep was fragmented with unusual wake-to-REM sleep transitions, both during the day and nighttime. In addition, PLC-beta4-/- mice reduced ultradian body temperature rhythms and elevated body temperatures during the daytime, but had normal homeothermal response to acute shifts in ambient temperatures (22 degrees C-4 degrees C). Within the most likely brain areas to produce these behavioral phenotypes, we found that, not orexin, but group-1 metabotropic glutamate receptor (mGluR)-mediated Ca(2+) mobilization was significantly reduced in the dorsal lateral geniculate nucleus (LGNd) of PLC-beta4-/- mice. Voltage clamp recordings revealed that group-1 mGluR-mediated currents in LGNd relay neurons (inward in wild-type mice) were outward in PLC-beta4-/- mice. CONCLUSIONS/SIGNIFICANCE: These lines of evidence indicate that impaired LGNd relay, possibly mediated via group-1 mGluR, may underlie irregular sleep sequences and ultradian body temperature rhythms in PLC-beta4-/- mice

Extension and its characteristics of ECRH plasma in the LHD

One of the main objectives of the LHD is to extend the plasma confinement database for helical systems and to demonstrate such extended plasma confinement properties to be sustained in steady state. Among the various plasma parameter regimes, the study of confinement properties in the collisionless regime is of particular importance. Electron cyclotron resonance heating (ECRH) has been extensively used for these confinement studies of the LHD plasma from the initial operation. The system optimizations including the modification of the transmission and antenna system are performed with the special emphasis on the local heating properties. As the result, central electron temperature of more than 10 keV with the electron density of 0.6 x 10$^{19}$ m$^{-3}$ is achieved near the magnetic axis. The electron temperature profile is characterized by a steep gradient similar to those of an internal transport barrier observed in tokamaks and stellarators. 168 GHz ECRH system demonstrated efficient heating at over the density more than 1.0 x 10$^{20}$ m$^{-3}$. CW ECRH system is successfully operated to sustain 756 s discharge.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France

Formation of electron internal transport barrier and achievement of high ion temperature in Large Helical Device

An internal transport barrier (ITB) was observed in the electron temperature profile in the Large Helical Device [O. Motojima et al., Phys. Plasmas 6, 1843 (1999)] with a centrally focused intense electron cyclotron resonance microwave heating. Inside the ITB the core electron transport was improved, and a high electron temperature, exceeding 10 keV in a low density, was achieved in a collisionless regime. The formation of the electron-ITB is correlated with the neoclassical electron root with a strong radial electric field determined by the neoclassical ambipolar flux. The direction of the tangentially injected beam-driven current has an influence on the electron-ITB formation. For the counter-injected target plasma, a steeper temperature gradient, than that for the co-injected one, was observed. As for the ion temperature, high-power NBI (neutral beam injection) heating of 9 MW has realized a central ion temperature of 5 keV with neon injection. By introducing neon gas, the NBI absorption power was increased in low-density plasmas and the direct ion heating power was much enhanced with a reduced number of ions, compared with hydrogen plasmas

Improved plasma performance on Large Helical Device

Since the start of the Large Helical Device (LHD) experiment, various attempts have been made to achieve improved plasma performance in LHD [A. Iiyoshi et al., Nucl. Fusion 39, 1245 (1999)]. Recently, an inward-shifted configuration with a magnetic axis position R_ax of 3.6 m has been found to exhibit much better plasma performance than the standard configuration with R_ax of 3.75 m. A factor of 1.6 enhancement of energy confinement time was achieved over the International Stellarator Scaling 95. This configuration has been predicted to have unfavorable magnetohydrodynamic (MHD) properties, based on linear theory, even though it has significantly better particle-orbit properties, and hence lower neoclassical transport loss. However, no serious confinement degradation due to the MHD activities was observed, resolving favorably the potential conflict between stability and confinement at least up to the realized volume-averaged beta of 2.4%. An improved radial profile of electron temperature was also achieved in the configuration with magnetic islands, minimized by an external perturbation coil system for the Local Island Divertor (LID). The LID has been proposed for remarkable improvement of plasma confinement like the high (H) mode in tokamaks, and the LID function was suggested in limiter experiments

Compatibility between high energy particle confinement and magnetohydrodynamic stability in the inward-shifted plasmas of the Large Helical Device

The experimentally optimized magnetic field configuration of the Large Helical Device [A. Iiyoshi et al., Nucl. Fusion 39, 1245 (1999)], where the magnetic axis is shifted inward by 15 cm from the early theoretical prediction, reveals 50% better global energy confinement than the prediction of the scaling law. This configuration has been investigated further from the viewpoints of high energy particle confinement and magnetohydrodynamic (MHD) stability. The confinement of high energy ions is improved as expected. The minority heating of ion cyclotron range of frequency was successful and the heating efficiency was improved by the inward shift. The confinement of passing particles by neutral beam injection was also improved under low magnetic field strength, and there could be obtained an almost steady high beta discharge up to 3% in volume average. This was a surprising result because the observed pressure gradient exceeded the Mercier unstable limit. The observed MHD activities became as high as beta but they did not grow enough to deteriorate the confinement of high energy ions or the performance of the bulk plasma, which was still 50% better than the scaling. According to these favorable results, better performance would be expected by increasing the heating power because the neoclassical transport can also be improved there

Observation of the “Self-Healing” of an Error Field Island in the Large Helical Device

It was observed that the vacuum magnetic island produced by an external error magnetic field in the large helical device shrank in the presence of plasma. This was evidenced by the disappearance of flat regions in the electron temperature profile obtained by Thomson scattering. This island behavior depended on the magnetic configuration in which the plasmas were produced