Biomedical subjects

H Sei

Publications and source records attributed to H Sei.

At least 37 records · Page 2Linked to original sources

PubMed1996

Acceleration of EEG theta wave precedes the phasic surge of arterial pressure during REM sleep in the rat.

We investigated temporal relationships among EEG theta frequency, eye movement (EM) burst and phasic surge of arterial pressure (AP) during rapid eye movement (REM) sleep in six rats. Changes in EEG theta frequency, EM number, mean AP (MAP) and heart rate (HR) during 1 s bins were obtained with reference to the onset of the EM bursts. The acceleration of EEG theta frequency preceded both the EM burst and the phasic increases of AP. The increase of MAP was closely correlated with the theta frequency but not the EM number during the period of EM burst. The possible involvement of the limbic system for the generation of phasic surge in AP during REM sleep is discussed.

Animals↗

PubMed1996

Effect of ambient temperature on arterial pressure variability during sleep in the rat.

Changes in mean arterial pressure (MAP) and heart rate (HR) during sleep were recorded at three ambient temperatures (Ta: 16, 22 and 28 degrees C). MAP and HR during sleep increased with lowering of Ta. The increase in MAP during the transition from NREM to REM sleep was decreased by lowering the Ta. At 28 degrees C, the average HR increased in going from NREM to REM sleep, while, at 16 degrees C, it decreased. The coefficient of variation (CV%) of the MAP during REM sleep decreased as the Ta was lowered, while that seen during NREM sleep was unchanged. This study suggests that Ta has a greater effect than sleep stage on the MAP and HR, and that MAP variability during REM sleep is greater at higher Ta.

Animals↗

PubMed1996

Effect of ambient temperature on power spectral density of arterial pressure during sleep in the rat.

Power spectral density (PSD) of arterial pressure (AP) during sleep was observed at various ambient temperatures (Ta: 16, 22 and 28 degrees C). Average AP and heart rate (HR) during sleep increased with lowering of Ta. PSD of AP during slow wave sleep (SWS) decreased over the entire range of frequency with increasing of Ta. Low frequency component (approximately 0.1 Hz) in PSD of AP during paradoxical sleep (PS) increased, while higher frequency component (0.1 Hz approximately) decreased with increasing of Ta. This study suggests that Ta affects the PSD of AP during sleep, and that vasomotor sympathetic tone during PS might increase with increasing of Ta.

Animals↗

PubMed1995

Effects of intravenously administered vitamin B12 on sleep in the rat.

Vitamin B12 (VB12) has been reported to normalize the entrainment of circadian rhythms in the non-24-h sleep wake cycle and delayed sleep phase insomnia in humans. The purpose of this work was to clarify whether the peripheral administration of VB12 has any sleep-promoting effect on the sleep-wake rhythm in freely moving rats. After a baseline day of saline infusion. VB12 (500 micrograms/kg/day) was administered continuously for 4 days via the jugular vein. Polysomnographic recordings were carried out concurrently. In both the light and the 24-h periods, the amount of non-rapid eye movement (NREM) sleep increased significantly on VB12-days 2 and 3, while the amount of REM sleep increased significantly on VB12-day 2. In the light period, the increase in NREM sleep was due to increased duration of the episode, while the tendency to an increase in REM sleep was due to an increased number of episodes. Changes in the diurnal sleep-wake rhythm tended to appear in the earlier light period. The serum VB12 concentrations in the VB12 group were 40 times higher than in controls. These findings suggest that peripherally infused VB12 has promoting effects on the rat's sleep, especially in the light period.

Animals↗

PubMed1995

Heart rate variability during sleep in Down's syndrome.

We observed heart rate (HR) variability in the sleep-wake cycle of young adults with Down's syndrome (DS) and their age-matched normal controls. Spontaneous HR fluctuations for 10 min during each sleep stage were analyzed by spectral analysis. Only during rapid eye movement (REM) sleep, a middle-frequency (0.05-0.15 cycles/beat) component of the HR fluctuations jointly mediated by the sympathetic and parasympathetic nerves, was significantly lower in the DS than in the control subjects. As the high-frequency (0.15-0.40 cycles/beat) component mediated by the parasympathetic nerve was not different in the two groups, it is suggested that the sympathetic activity during REM sleep is lower in DS than in controls.

Adult↗

PubMed1995

Effect of decerebration on blood pressure during paradoxical sleep in cats.

We investigated the effects of decerebration on long-term variations in arterial blood pressure during paradoxical sleep (PS) in cats. In normal cats, the blood pressure decreased during the transition from slow wave sleep to PS and maintained its lower level throughout PS for several days after surgery. After this early postoperative stage, however, the arterial hypotension was replaced by tonic and phasic rises in blood pressure during PS. Such long-term changes in blood pressure were completely abolished when the brain stem was transected at the ponto-mesencephalic junction, and the cats consistently exhibited a sustained fall in blood pressure throughout the survival periods of 1 month or more.

Animals↗

PubMed1994

Postoperative changes of rat EEG variance.

Concerning an EEG parameter variance, the long-term postoperative changes were observed in rats chronically implanted with bipolar depth electrodes for EEG recordings. The cortico-hippocampal EEG signals were continuously digitized and their variances were computed for each 1 min in real time. Daily mean of the EEG variance gradually increased over 2 weeks after surgery for the implantation of chronic electrodes and, then, reached a plateau. To observe the absolute quantity of the depth EEG in the rat, at least 2 weeks are required before data collections.

Animals↗

PubMed1994

Long-term variations of arterial blood pressure during sleep in freely moving cats.

Using a new telemetric system for arterial blood pressure recordings, we have investigated long-term postoperative changes in blood pressure during sleep in freely moving cats. Particular attention was paid to the transitional periods at the beginning and end of paradoxical sleep (PS), as well as to the relationship between the blood pressure and ponto-geniculo-occipital (PGO) waves. In the initial postoperative stage lasting 2 to 5 days, the blood pressure decreased during the transition from slow wave sleep (SWS) to PS and maintained its lower level until the end of PS. In contrast, in the later chronic stage, the blood pressure increased tonically during the transition from SWS to PS and maintained its higher level throughout PS on which several phasic rises in blood pressure were superimposed. A significant increase in arterial pressure during the transitional period began shortly after the first appearance of PGO waves. On the other hand, significant phasic rises in arterial pressure during PS shortly preceded the onset of PGO wave bursts.

Animals↗

PubMed1994

Response of the sleep-wake rhythm to an 8-hour advance of the light-dark cycle in the rat.

We have studied the effects of an 8-h advance of the environmental light-dark (LD) cycle on the sleep-wake rhythm in the rat. Electroencephalograms and electromyograms were recorded simultaneously on chart paper through a two-channel telemetry system for 3 days before phase shift (baseline) and 8 days during and after phase shift. Phase advance of the LD cycle led to an increase in both non-rapid eye movement (NREM) and REM sleep. The amount of NREM sleep in the light period correlated positively with that in the preceding dark period for 4 days after phase advance. The duration of REM sleep in the light period correlated negatively with that in the preceding dark period. The results suggest that homeostatic control of the amount of NREM sleep between the preceding dark period and the following light period is disturbed by phase advance of the LD cycle.

Activity Cycles↗

PubMed1994

Power spectral analysis of blood pressure fluctuations during sleep in normal and decerebrate cats.

Arterial blood pressure fluctuations during sleep were investigated with power analysis technique in both normal and decerebrate cats. In the initial postoperative stage lasting about 3 to 4 days, intact cats displayed, during paradoxical sleep, phasic increases in arterial blood pressure which were superimposed on a tonic hypotension. In the later chronic stage, however, the animals showed the phasic hypertension being superimposed on the background of a tonic hypertension. Regardless of these stages, the blood pressure during paradoxical sleep exhibited a 1/f-like spectrum, expressed by the power spectral density which is inversely proportional to the Fourier frequency f. On the other hand, a power spectral profile of the blood pressure during slow wave sleep presented a white noise-like pattern within the same frequency range of 0.1-0.01 Hz. After brainstem transections at the pontomesencephalic border, the cats exhibited consistently a sustained fall in blood pressure during paradoxical sleep and the power spectral density of the blood pressure displayed a white noise-like pattern throughout the survival periods of one month or more. These observations indicate that the blood pressure fluctuations in the 1/f spectrum during paradoxical sleep originate in rostral brain structures.

Animals↗

PubMed1993

Spectral analyses of PGO-on neurons during paradoxical sleep in freely moving cats.

We have investigated the power spectral density (PSD) characteristics of spontaneous neuronal activities during paradoxical sleep (PS), including phasically firing PGO-on and tonically discharging type I-R neurons in the pontine tegmentum. The PSD of lateral geniculate PGO waves and blood pressure (BP) were also examined. During PS, the PSD of PGO-on neurons and PGO waves showed an almost white noise-like pattern, while that of TI-R neurons and BP exhibited a 1/f spectrum. It appears, therefore, that the neuronal and autonomic slow fluctuations found in the 1/f spectrum during PS are not driven by the PGO wave system.

Animals↗

PubMed1992

Effects of an eight-hour advance of the light-dark cycle on sleep-wake rhythm in the rat.

We observed effects of an 8-h advance of the light-dark (LD) cycle on the sleep-wake rhythm in the rat. On the day phase-advanced, rapid eye movement (REM) sleep increased with its enhanced diurnal amplitude. Non-REM (NREM) sleep gradually increased in parallel with the decrease of its diurnal amplitude. Although the acrophase of NREM sleep gradually advanced after the phase advance, that of REM sleep did not significantly change. We confirmed that diurnal rhythm of REM sleep was hardly shifted and dissociated from the rhythm of NREM sleep under the eight-hour advance of the LD cycle in the rat.

Animals↗

PubMed1992

Relationship between eye movements and oneiric behavior in cats.

The relation between oneiric behavior and rapid eye movements (REMs) in paradoxical sleep (PS) without muscle atonia was analyzed in cats. Most isolated REMs were related to orienting behavior, whereas most REM bursts were related to generalized body movements (jumping, attacking, etc.). Only isolated, high amplitude REMs had any possibility of corresponding to visual images in dreams. From these findings we propose the existence of both dream-related and nondream-related REMs even in animals.

Animals↗

PubMed1992

Diurnal monoamine variation in young and old rats: a microdialysis study.

The levels of striatal extracellular DA, DOPAC, HVA and 5-HIAA significantly decreased in aged rats compared to young adults. The magnitude of age-related reduction was greater in dopaminergic than serotonergic substances. The levels of striatal extracellular monoamines in young adult rats showed significant diurnal variations. On the other hand, these substances of aged rats, except for HVA, did not exhibit significant diurnal variations. Enriched environment housing increased levels of striatal extracellular DOPAC in aged rats, but did not influence on the age-related changes of diurnal variations in the striatal extracellular monoamines.

Aging↗

PubMed1991

Diurnal changes in pineal extracellular indoles of freely moving rats.

We observed 24 h changes of 'extracellular' indoleamines in pineal microdialysates taken from freely moving rats under a 12 h light/12 h dark cycle. Pineal indoleamines in microdialysates were analyzed by high-performance liquid chromatography with electrochemical detection. Consequently, they exhibited marked diurnal variations. The diurnal level in the extracellular 5-HT, higher for the light and lower for the dark, was parallel to that in 5-hydroxyindoleacetic acid and diametrically opposite to that in N-acetylserotonin (NAS). The release of 5-HT into the extracellular space transiently increased for the first 2 h after the dark onset and then became lower during the dark.

Animals↗

PubMed1991

Ultradian rhythm of 100 min in the dark phase EEG of the rat.

Using the "variance in statistics" as an index of electroencephalogram (EEG) parameters, we observed the cortico-hippocampal EEG rhythm under a 12:12-h light-dark condition in the rat with chronically implanted electrodes for EEG recording. The above EEG variance was simply measured in real time and on line through a personal computer. It corresponded to EEG slow wave activity and expressed the process of slow wave sleep as described in the two-process model by Borbély et al. Only in the dark phase, mean power spectral density of the EEG variance had a significant peak at about 1/100 cycles/min. This 100-min rhythmicity similar to the basic rest-activity cycle in human beings was observed in rats, particularly in the dark (active) phase for nocturnal animals. We propose that this ultradian 100-min rhythm is essential for the rat to maintain the waking state dominantly over the 12-h dark period.

Animals↗

PubMed1991

Pineal microdialysis in freely moving rats.

We describe a surgical technique to implant the guide cannula for in vivo microdialysis in the rat pineal gland. This technique has the following features and advantages: (a) does not require ligation of the superior or transverse sinus, (b) minimizes bleeding from the dural veins, (c) does not disturb the sympathetic innervation originating from superior cervical ganglia, which is essential for pineal function. This new technique makes it possible to carry out chronic pineal microdialysis of freely moving rats.

Animals↗

PubMed1991

Real-time monitoring of slow-wave sleep by electroencephalogram variance.

Based on statistical variance as an index of electroencephalogram (EEG) parameters, we monitored slow-wave sleep in both humans and rats in real time and on-line with a widely used personal computer. This EEG variance method may be a useful tool to carry out biological rhythm research, including sleep studies.

Analysis of Variance↗