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S Inoué

Publications and source records attributed to S Inoué.

At least 55 records · Page 3Linked to original sources
PubMed1996

State-dependent changes of extracellular glutamate in the medial preoptic area in freely behaving rats.

Microdialysis technique was applied to the medial preoptic area (mPOA) of the hypothalamus, a crucial site for the regulation of sleep, in order to analyze the interrelationship between the extracellular level of glutamate (Glu) and the vigilance states. Dialysates from the mPOA were sampled at 5-min intervals for 2-h diurnal period with a perfusion rate of 2.0 microliters/min in freely moving rats, whose sleep-waking behaviors were polysomnographically monitored. Extracellular Glu increased during wakefulness, exhibiting a peak at the transition period from wakefulness to non-rapid-eye-movement sleep (NREMS) (18.0% above the average), whereas it decreased during NREMS (9.2% below the average). It is likely that Glu in the mPOA is dynamically involved in the alterations of the vigilance states.

Animals↗
PubMed1996

Vitamin B12 amplifies circadian phase shifts induced by a light pulse in rats.

Vitamin B12 (VB12) is a putative modulator of the human circadian clock, improving entrainability to the 24 h light-dark cycle. The present study was intended to elucidate the mechanism of VB12 action in an animal model. In male rats free-running under constant dim illumination, a single light pulse of 50-1000 lux for 20 min given at circadian time (CT) 20 induced a 0.28 to 1.08 h phase advance and at CT 14 induced a 0.54 to 2.10 h phase delay. A 3 h intracerebroventricular (icv) infusion of 30 nmol VB12 starting 2 h prior to a 20 min 200 lux light pulse significantly amplified phase shifts in comparison with saline-treated or untreated controls. The mean phase advance (1.13 h) was 1.8-fold greater than that of saline-infused controls, whereas the mean phase delay (2.28 h) was 2.9-fold greater. These values were comparable to the maximal phase shifts caused by 1000 lux light pulses in untreated rats. Since the same VB12 treatment alone had failed to induce a phase shift in a previous experiment, these results indicate that VB12 strongly enhanced light pulse-induced phase shifts and thus augmented the entrainability of the circadian clock to light.

Animals↗
PubMed1996

Characteristic changes in sleep patterns during pregnancy in rats.

The purpose of this study was to evaluate changes in sleep patterns during pregnancy to better understand sleep regulation during pregnancy. We uninterruptedly recorded electroencephalogram (EEG), electromyogram (EMG), and brain temperature (Tbr) throughout pregnancy in rats. The duration of non-rapid eye movement (non-REM) sleep decreased after day 5 of pregnancy associated with an inverse increase in the number of non-REM sleep episodes. Thus, the amount of total non-REM sleep time remained constant throughout pregnancy. The amount of total REM sleep time decreased on day 17 of pregnancy after which the reduced state was sustained. That was mainly due to a decrease in the number of REM sleep episodes. Brain temperature (Tbr) gradually decreased as pregnancy advanced, reaching its lowest value 3 days before delivery. These observations provide a better understanding of the sleep patterns during pregnancy, and useful information for investigation of mechanisms of sleep regulation during pregnancy.

Animals↗
PubMed1996

Pregnancy-associated sleep changes in the rat.

Sleep disorder during the course of pregnancy has been recently recognized in humans. However, the underlying mechanism of pregnancy-associated sleep disorder remains undetermined, and sleep changes even during normal pregnancy have not been fully understood. To describe the effects of pregnancy on sleep, sleep-wake patterns before and after fertile mating were compared in an animal model. Baseline recordings of sleep and brain temperature were made throughout a normal 4-day estrous cycle in female rats. After the rats became pregnant, the recordings continued across the entire pregnant period. Compared with baseline sleep before mating, both non-rapid eye movement sleep and rapid eye movement sleep increased significantly from the first night of pregnancy. Although rapid eye movement sleep returned to the baseline level from midpregnancy, nocturnal non-rapid eye movement sleep stayed enhanced during the entire pregnant period. Daytime sleep fluctuated toward the end of pregnancy. Brain temperature was elevated during the early period of pregnancy but did not correlate with enhanced sleep. The results suggest that physiological changes in different stages of pregnancy may contribute to the regulation of maternal sleep and temperature.

Animals↗
PubMed1996

Mitotic organization and force generation by assembly/disassembly of microtubules.

The sites and roles of microtubule assembly/disassembly in mitosis are reviewed, together with evidence that microtubule assembly can push, and disassembly can pull, organelles such as the kinetochore on chromosomes which remain attached to the assembling or disassembling end of the microtubule, in vivo and in vitro. Motor proteins with weakened or inhibited transport activity can bind objects to the assembling or disassembling microtubule end, and may be involved in the dynamic attachment of the kinetochore to the spindle microtubules in mitosis.

Animals↗
PubMed1995

Sleep patterns in cyclic and pseudopregnant rats.

In order to clarify the relationship between sleep and reproductive activities, time-course changes in sleep were analyzed in normal female rats. The state of sleep-wakefulness was continuously monitored for 4 weeks including two-consecutive 4-day estrous cycles, a 12-day pseudopregnant period and a subsequent 4-day cycle. Sleep patterns in estrous cycle were characterized by a marked reduction in nocturnal non-rapid-eye-movement sleep (NREMS) and rapid-eye-movement sleep (REMS) at proestrus. A significant increase in nocturnal NREMS and REMS occurred immediately after the induction of pseudopregnancy by sterile mating, lasting for the whole pseudopregnant period for NREMS and during the early and mid period for REMS. In contrast, diurnal REMS tended to decrease towards the end of pseudopregnancy. The circadian rhythm of brain temperature exhibited no reproductive activity-dependent change. The dynamic changes in sleep may correlate alterations in neuroendocrine activities specific to estrous cycles and pseudopregnancy.

Animals↗
PubMed1995

Force generation by microtubule assembly/disassembly in mitosis and related movements.

In this article, we review the dynamic nature of the filaments (microtubules) that make up the labile fibers of the mitotic spindle and asters, we discuss the roles that assembly and disassembly of microtubules play in mitosis, and we consider how such assembling and disassembling polymer filaments can generate forces that are utilized by the living cell in mitosis and related movements.

Animals↗
PubMed1994

Oxidized glutathione regulates physiological sleep in unrestrained rats.

Oxidized glutathione (GSSG) is an active component of sleep-promoting substance (SPS) which was originally extracted from the brainstems of 24-h sleep-deprived rats. We analyzed somnogenic and thermoregulatory activities of five doses of GSSG in unrestrained rats. A nocturnal 10-h intracerebroventricular infusion of GSSG significantly enhanced slow wave sleep (SWS) at the dosage range from 20 to 50 nmol and paradoxical sleep (PS) at 25 nmol at the expense of wakefulness during the 12-h dark period. The dose-response relations exhibited a bell shape for both SWS and PS. The administration of 25 nmol/10 h GSSG induced the maximal increase in the total time of nocturnal sleep (35% above the baseline for SWS and 86% for PS). The enhancement of sleep was mainly due to an increase in the duration of SWS episodes and in the number of PS episodes. GSSG at 25 nmol/10 h elicited significant fluctuations in brain temperature (Tbrain), biphasic hypothermal and hyperthermal reactions during the infusion period, followed by a hyperthermal state during the subsequent light period of the recovery day and then a hypothermal state during the dark period. On the basis of recent literature on the inhibitory action of GSSG on the excitatory synaptic membrane of rat brain, we speculate that the sleep-enhancing activity of GSSG was caused by its physiological modulation on the glutamatergic neurotransmission in the brain.

Animals↗
PubMed1993

Lateral preoptic lesions void slow-wave sleep enhanced by uridine but not by muramyl dipeptide in rats.

We investigated the site of action of two sleep-inducing substances, viz., muramyl dipeptide (MDP) and uridine. Localized electrolytic lesions were made bilaterally in the lateral preoptic hypothalamus (LPO) in rats and nocturnal 10-h i.c.v. infusions of MDP and uridine were performed before and after the LPO lesions. MDP increased only slow-wave sleep (SWS) in both intact and LPO-lesioned rats. Uridine promoted both SWS and paradoxical sleep (PS) before the LPO lesions whereas it increased only PS after the lesions. These results suggest that the LPO is crucial for SWS-promoting action of uridine but not MDP.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1993

Differential sleep modulation by sequentially administered muramyl dipeptide and uridine.

In an attempt to investigate the effects on sleep modulation of order of administration of two substances, sequential intracerebroventricular (ICV) infusions of muramyl dipeptide (MDP, 1.0 nmol) and uridine (5.0 pmol) were conducted in freely behaving rats. To eliminate the influence of intermittent infusions on their behavior, the rats were continuously ICV infused with physiological saline solution, which did not affect their normal sleep-waking dynamics. Under these experimental conditions, uridine infusion (2400-0500 h) attenuated the enhancement of slow-wave sleep (SWS) caused by prior infusion of MDP (1900-2400 h) to the baseline level and, thus, did not exert a sleep-promoting property. In contrast, MDP infusion (2400-0500 h) further potentiated the SWS-enhancing activity of preinfused uridine (1900-2400 h). A single infusion of MDP or uridine (2400-0500 h) similarly enhanced SWS. These results demonstrate that observed differences in the induction and maintenance of sleep are dependent upon the order of exogenously infused uridine and MDP. The time sequence per se of these sleep substances may be responsible for the differential temporal changes in sleep. It is, therefore, assumed that a crucial order of multiple sleep substances may dynamically and differentially regulate sleep in the brain.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1993

Image sharpness and contrast transfer in coherent confocal microscopy.

Confocal microscopes provide clear, thin optical sections with little disturbance from regions of the specimen that are not in focus. In addition, they appear to provide somewhat greater lateral and axial image resolution than with non-confocal microscope optics. To address the question of resolution and contrast transfer of light microscopes, a new test slide that enables the direct measurement of the contrast transfer characteristics (CTC) of microscope optics at the highest numerical aperature has been developed. With this new test slide, the performance of a confocal scanning laser microscope operating in the confocal reflection mode and the non-confocal transmission mode was examined. The CTC curves show that the confocal instrument maintains exceptionally high contrast (up to twice that with non-confocal optics) as the dimension of the object approaches the diffraction limit of resolution; at these dimensions, image detail is lost with non-confocal microscopes owing to a progressive loss of image contrast. Furthermore, we have calculated theoretical CTC curves by modelling the confocal and non-confocal imaging modes using discrete Fourier analysis. The close agreement between the theoretical and experimental CTC curves supports the earlier prediction that the coherent confocal and the incoherent non-confocal imaging mode have the same limit of resolution (defined here as the inverse of the spatial frequency at which the contrast transfer converges to zero). The apparently greater image resolution of the coherent confocal optics is a consequence of the improved contrast transfer at spacings which are close to the resolution limit.

Diatoms↗
PubMed1991

Cell division in Dictyostelium with special emphasis on actomyosin organization in cytokinesis.

This study focuses on the dynamic reorganization of actin and myosin ("conventional" myosin, or myosin-II) during cytokinesis in D. discoideum. This is the first study identifying the birefringence of the spindle microtubules as well as three sets of microfilamentous structure in Dictyostelium. The change of organization in these fibrillar structures was followed in real-time with video microscopy, using a Universal Polarizing Microscope equipped with polarized-light (POL) and differential interference contrast (DIC) optics combined with digital image processing. High-frequency mitotic cells were obtained by semi-synchronous culture, and high-resolution observations were made by utilizing the agar-overlay method (Yumura et al.: Journal of Cell Biology 99:894-899, 1984). The molecular identity of the birefringent structures was determined by fluorescence microscopy. Through-focus observations were performed with an axial resolution of 0.3 micron depth of field. The actomyosin fibrils show a dramatic reorganization throughout mitosis. The fibrils at the leading lamellipodia disappear, and there is a striking assembly of the cortical actomyosin in pro-metaphase, which is accompanied by a decrease in cell volume. The cortical actomyosin gradually increases through anaphase. After late anaphase, very active polar lamellipodia, with an average life of less than 1 minute, are formed. We confirmed that the polar lamellipodia include actin, but not myosin-II. At the cleavage furrow, the microfilaments form two distinctive structures: circular contractile ring at the equator, and a cortical filament array parallel to the polar axis. Myosin is localized in the contractile ring, but not associated with the axial array of F-actin. Actomyosin in the contractile ring gradually transforms into cortical network at the posterior region of daughter cells. The constriction of the furrow is accompanied by a drastic efflux of water as evidenced by highly active contractile vacuole formation and turbulent motion of minute vesicles connected to the furrow. This study demonstrates the presence of a new microfilament structure, as well as the dynamic property of the contractile ring, and sheds new light on the contractile mechanisms underlying cytokinesis.

Actomyosin↗
PubMed1990

Effects of medial preoptic area lesions on sleep and wakefulness in unrestrained rats.

Bilateral radiofrequency lesions of the medial preoptic area (MPOA) in unrestrained male rats resulted in a significant decrease in slow wave sleep (SWS) in the light period throughout two postoperative weeks, although the night-active pattern of circadian rhythms was little affected. Both diurnal and nocturnal paradoxical sleep (PS) gradually increased after the lesions. Within one week, however, the daily amount of total sleep (SWS + PS) was recovered to the normal level, since the loss of diurnal SWS was compensated by an increase in nocturnal sleep at the expense of wakefulness. The MPOA lesions brought about a transient elevation of brain temperature, which lasted only for the diurnal period of the day of lesioning. It is speculated that the MPOA plays a definite role in the passage of sleep-regulatory information, especially concerning the circadian distribution of sleep.

Animals↗
PubMed1990

Chronic intake of panax ginseng extract stabilizes sleep and wakefulness in food-deprived rats.

The amount of wakefulness and slow wave sleep significantly fluctuated during 48 h food deprivation and subsequent recovery periods in freely behaving male rats. In contrast, such fluctuations were significantly less prominent in age-matched male rats chronically treated with Panax ginseng extract via drinking water. It is speculated that the ginseng extract may exert a stabilizing effect on sleep-waking disturbances which possibly accounts for its outstanding health-improving activities.

Animals↗