Biomedical subjects

H Sei

Publications and source records attributed to H Sei.

At least 19 recordsLinked to original sources

PubMed2005

Tyramine-immunoreactive neuronal structures in the rat brain: abundance in the median eminence of the mediobasal hypothalamus.

Immunoreactivity to p-tyramine, one of the natural trace amines, was studied in the rat brain by an anti-p-tyramine antibody. Immunoreactivity to this amine is very weak in the nigrostriatal dopaminergic neurons and terminals, and weak in the locus coeruleus noradrenergic ones. It was intensified in these structures after monoamine oxidase inhibition. On the other hand, this amine was highly concentrated in the median eminence of the mediobasal hypothalamus, in which its physiological function on prolactin release has been demonstrated.

Animals↗

PubMed2003

Increase of hippocampal acetylcholine release at the onset of dark phase is suppressed in a mutant mice model of evening-type individuals.

We have previously reported that clock mutant mice on Jcl:ICR background show about 2-h delayed circadian profiles in body temperature, spontaneous activity and sleep-wake rhythm, and that they appear to be useful as a model of evening-type of individual. Hippocampal acetylcholine (ACh) release which is positively correlated with attention, learning and memory shows a circadian variation. In this study, changes in hippocampal ACh release in transitional phase from light (rest) to dark (active) period in clock mutant mice were monitored using an in vivo microdialysis method. Compared with wild mice, the increase in hippocampal ACh in the first 2 h of the active period in the mutant mice was suppressed in parallel with peak frequency in electroencephalogram theta rhythm. The molecular basis of the circadian system appears to have a strong effect on hippocampal cholinergic function, and is probably associating with individual temporal differences in voluntary behavior, cognition, learning and/or memory performance.

Acetylcholine↗

PubMed2002

Influence of sleep disturbance on steroid 5alpha-reductase mRNA levels in rat brain.

Sleep deprivation has been shown to affect the production of steroid hormones in peripheral steroidogenic organs, but little is known about the influence of sleep disturbance on the metabolism of steroid hormones in the brain. To elucidate a possible association of the sleep-wake cycle with brain neurosteroid metabolism, the influence of short-term sleep disturbance on the expression of mRNA encoding steroid 5alpha-reductase, the enzyme converting progesterone and other steroid hormones to their neuroactive 5alpha-reduced metabolites, was investigated. Rats were first subjected to non-selective disturbance of the sleep-wake cycle, and the expression of steroid 5alpha-reductase mRNA in rat hippocampus and brainstem was determined using a semi-quantitative one-step RT-PCR technique. Non-selective disturbance of the sleep-wake cycle resulted in the elevation of 5alpha-reductase mRNA levels in the brainstem, but not in the hippocampus, and the elevated mRNA expression returned to the basal levels after a short period of the sleep recovery. Further studies showed that selective REM sleep deprivation significantly elevated 5alpha-reductase mRNA levels in both hippocampus and brainstem, thus proposing the possibility that REM sleep reduction may largely contribute to the elevation of steroid 5alpha-reductase mRNA levels observed during short-term disturbance of the sleep-wake cycle. Since the enhancement of steroid 5alpha-reductase gene expression may result in the elevation of neuroactive 5alpha-reduced steroid production in the brainstem, the findings presented here provide further evidence for suggesting that neuroactive steroids may play a physiologically important role in the neuronal network for REM sleep initiation and maintenance.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMed2001

Semi-quantitative RT-PCR analysis of environmental influence on P450scc and PNMT mRNA expression in rat adrenal glands.

Environmental influence on brain function, particularly spatial learning and memory, has been extensively investigated, but little is known about the influence of environmental conditions on the functions of peripheral organs. In the present study, the effects of different housing conditions on the steady-state levels of mRNAs encoding cholesterol side-chain cleavage enzyme (cytochrome P450scc) and phenylethanolamine N-methyltransferase (PNMT) in adrenal glands was examined to investigate the environmental influence on both adrenocortical and adrenomedullary functions. Behavioral changes of the animals housed in different conditions were first examined to assess the relevance of environmental manipulation used. In consistent with previous findings, housing of the animals in enriched conditions resulted in the significant reduction of spontaneous motor activity (locomotor activity and rearing) in comparison with housing in isolated conditions, thus indicating the relevance of housing conditions used in this work for investigating the environmental influence on adrenal function. Then, the effects of these housing conditions on P450scc and PNMT mRNA levels in adrenal glands were examined using semi-quantitative RT-PCR method. In comparison with the isolated group, the enriched group showed significantly higher levels of P450scc mRNA. In contrast, PNMT mRNA levels in the enriched group were significantly lower than those in the isolated group. These results propose the possibility that the environmental conditions may cause differential alterations in adrenocortical and adrenomedullary functions, although their possible association with behavioral changes still remains to be elucidated.

Adrenal Glands↗

PubMed2001

Mouse model for morningness/eveningness.

Human morning/evening preferences has recently been reported to be associated with polymorphism of the 3' flanking region of the Clock gene, which was the first identified mammalian circadian clock gene. We recorded body temperature, spontaneous activity, electroencephalogram and electromyogram for 48 h in mice with Jcl:ICR genetic background and homozygous for the Clock mutation (Cl/Cl on Jcl:ICR). In both wild-type and Cl/Cl on Jcl:ICR, body temperature, activity, wake and sleep were completely entrained to LD cycle. However, phases of the rhythm for body temperature, activity and wake duration in the Cl/Cl on Jcl:ICR were about 2 h delayed in comparison with the wild-type. This study has provided further evidence on the close relationship between human morning/evening preference and the molecular basis of circadian clock system, and has suggested that Cl/Cl on Jcl:ICR is useful for an animal model for human morning/evening preference.

Animals↗

PubMed2000

Differential effect of short-term REM sleep deprivation on NGF and BDNF protein levels in the rat brain.

It is well known that REM sleep is associated with memory consolidation, especially, procedural skill learning. Neurotrophic factors are known to be involved in synaptic plasticity. We therefore investigated the effects of selective REM sleep deprivation (RSD) on NGF and BDNF proteins in the hippocampus, cerebellum and brainstem in the rat. NGF and BDNF were detected by an ELISA. Our findings show that 6 h RSD affected the NGF and BDNF protein levels in different manner. In the cerebellum and brainstem, BDNF was significantly decreased, while NGF was not changed. Conversely, in the hippocampus, NGF was significantly decreased while BDNF was not changed. This study indicates that REM sleep may be associated with the secretion of neurotrophic factors and thus contribute to the memory functions.

Animals↗

PubMed1999

Sympathetic activity in alexithymics with mother's low care.

This study examines the relationships between alexithymic characteristics and their psychological factors (i.e., maternal closeness) and the sympathetic system in a sample of male college students. At the resting period, low frequency (LF)/ high frequency (HF) ratio, as an index of sympathetic activity, was significantly higher for students with high scores on global alexithymia or its alexithymia factor (difficulty describing feelings) than those with low scores, suggesting that alexithymic students tend to indicate high sympathetic activity during the resting period. During stress, the increase of LF/HF ratio was higher for students with low scores on alexithymia than those with high scores. Although no significant differences were noted, one may speculate that the differences in stress-related activation of LF/HF are due to higher levels of LH/HF in high alexithymics prior to stress. Our findings indicate that significant association between alexithymia and sympathetic activity during the resting period was controlled for the level of mother's care, suggesting that maternal attachment in infancy and/or childhood may play an important role in the development of alexithymic characteristics and/or sympathetic activity during the resting period.

Adaptation, Psychological↗

PubMed1999

Sino-aortic denervation augments the increase in blood pressure seen during paradoxical sleep in the rat.

Using a computer assisted telemetric system, we have re-examined the effect of sino-aortic denervation (SAD) on the changes in arterial blood pressure (AP) and heart rate (HR) during sleep in the rat suitably recovered from the operation. Eight 1 hourly polygraphic recordings were performed 4 weeks after the initial SAD surgery. In the SAD rats, the increase in AP during paradoxical sleep (PS) was much larger than that in sham-operated rats. HR in the SAD rats increased on-going from slow-wave sleep to PS, but it showed no change in sham-operated rats. The present study suggests that chronic SAD causes the enhanced AP increase during PS concomitantly with the persistent hypertension and tachycardia across sleep-wake states.

Animals↗

PubMed1999

Why does arterial blood pressure rise actively during REM sleep?

A large fluctuation in autonomic function is one of the most important characteristics of REM sleep. Arterial blood pressure (AP) increases during the transition from non-REM to REM sleep, showing phasic surges during REM sleep. REM-associated AP changes involve 1) a long-term recovery process after surgery, 2) circadian rhythm, 3) relationships with ambient temperature. REM-associated AP changes are mediated by sympathetic nerves, buffered by baroreflex, abolished in decerebrated cats, and related to hippocampal theta activity in rats. Furthermore, the midbrain dopaminergic system has been recently found to be involved in increases in REM-associated AP.

Animals↗

PubMed1999

The N400 event-related potential in aphasia.

Although the N400 component of event-related potentials (ERPs) is suggested to reflect language processing, exactly which language processing functions N400 is sensitive to is not clear. We investigated this component in aphasic patients with some impairments of language processing. Meaningful and meaningless words in Kana (Japanese characters) were used as stimuli under a visual oddball paradigm. Increases in N400 latency and amplitude in the aphasic group were significant in comparison with the control group. In the aphasic group, N400 latency correlated significantly with the performance intelligence quotient employed besides language quotients. Moreover, the N400 effects were seen more clearly in the left hemisphere than in the right hemisphere for both groups. We propose that the abnormal variations in amplitude or latency of N400 in the aphasic group reflect language processing functions (controlled processing and automatic processing) that are different between slight and severe cases of aphasia. Moreover, N400 effects are sensitive to intellectual abilities besides language ability. We also suggest that N400 effects in the left hemisphere for the aphasic group are a reflection of active language processing as the substitution function.

Adult↗

PubMed1999

Injection of 6-hydroxydopamine into the ventral tegmental area suppresses the increase in arterial pressure during REM sleep in the rat.

We have examined the effect of injection of 6-hydroxydopamine (6-OHDA) into the ventral tegmental area (VTA) on the changes in arterial blood pressure (AP) and heart rate (HR) during the transition from non-rapid eye movement (NREM) sleep to REM sleep. The 6-OHDA-treated rats showed suppression of the increase of AP and HR during REM sleep and of theta frequency in the cortical electroencephalogram (EEG) during wakefulness (W) and REM sleep. It is suggested that midbrain dopaminergic neurons are involved in the control of AP and HR during REM sleep and in the EEG theta activity.

Analysis of Variance↗

PubMed1998

The effects of acetazolamide on arterial pressure variability during REM sleep in the rat.

During rapid eye movement (REM) sleep, the arterial pressure (AP) undergoes large fluctuations in the rat, cat, and other mammals, including humans, and it has been suggested that this effect originates in the forebrain. In addition, acetazolamide (ACTZ), a carbonic anhydrase inhibitor, is known to be effective in the treatment of central sleep apnea or epilepsy. The aim of the present study was to analyze the effects of ACTZ on EEG theta rhythm and AP variability during REM sleep in rats. Treatment consisted of intraperitoneal injection of 5 mg of ACTZ in 0.5 mL of saline (n = 6) or 0.5 mL of vehicle alone (n = 6). We then recorded and analyzed the mean AP (MAP) variations during different sleep phases, using a telemetric system. Our results show: 1) Significant decreases in the coefficient of variation of MAP, in the very-low frequency (0.025 - 0.225 Hz) component of the power spectral density of the AP and in theta frequency in the electroencephalogram, were seen in the ACTZ-treated group during REM sleep compared with controls, whereas no significant difference was found between the two groups in non-REM sleep. There was no significant difference in sleep duration, average MAP, and heart rate between the groups. Our data suggest that ACTZ may act as a stabilizing factor preventing AP fluctuations during REM sleep.

Acetazolamide↗

PubMed1998

Influence of cedar essence on spontaneous activity and sleep of rats and human daytime nap.

We investigated whether exposure to the odor of extracted cedar essence (CE) has (i) an influence on spontaneous activity and sleep-wake states of rats and (ii) a sleep-promoting effect on human daytime nap after taking an ordinary night's sleep. In rats exposed to CE, spontaneous activities and amount of wake were significantly decreased, while the amount of non-rapid eye movement (NREM) sleep was significantly increased. In human daytime nap, NREM sleep stage 2 latency was significantly shortened after exposure to CE.

Animals↗

PubMed1997

Diurnal change of arachidonate 12-lipoxygenase in rat pineal gland.

Rat pineal gland contains a 12-lipoxygenase as demonstrated by the enzyme activity, RNA blot analysis and in situ hybridization. Using rats maintained with 12-h dark and light cycles, dynamic changes of the enzyme in pineal gland were examined. When the crude extract of pineal glands was incubated with arachidonic acid and the reaction products were analyzed by reverse-phase HPLC, the glands obtained from rats in the dark showed a higher 12-lipoxygenase activity than those obtained from rats in the light. The pineal 12-lipoxygenase activity decreased after the light was on at 7 o'clock and reached the lowest level around 16 o'clock. Upon Western blot analysis the amount of 12-lipoxygenase protein in pineal glands was high in the dark and lowest around 16 o'clock. A half life of the enzyme protein was estimated to be approximately 2.8 h in organ culture of rat pineal glands. Northern blot analysis also revealed a higher 12-lipoxygenase mRNA level in pineal glands obtained in the dark than those obtained in the light. Thus, the 12-lipoxygenase of rat pineal glands shows a diurnal fluctuation that is regulated at the transcription level, and may play a certain role in the regulation of neuroendocrine processes of this gland.

Animals↗

PubMed1997

Effect of vitamin B12 on the sleep-wake rhythm following an 8-hour advance of the light-dark cycle in the rat.

We have studied the effect of vitamin B12 (VB12) on the sleep-wake rhythm following an 8-h advance of the light-dark (LD) cycle in the rat. The electroencephalogram and electromyogram were recorded on chart paper via a two-channel telemetry system. Infusion of VB12 (Mecobalamin; 0.25 microgram/h) or saline into the abdominal cavity was performed using an implanted miniosmotic pump. Before the phase shift, there was no significant difference between the two groups in terms of the mean daily amount of each vigilance stage. Following the phase advance, in the saline group, wake gradually decreased and nonrapid-eye-movement (NREM) sleep and REM sleep increased. In the VB12 group, no significant change was seen in any of the vigilance states, except for REM sleep on day 3. The results suggest that VB12 may maintain homeostasis of sleep and/or wake amount following an 8-h advance of the LD cycle in the rat.

Animals↗

PubMed1997

Diurnal changes of blood pressure, heart rate and body temperature during sleep in the rat.

We have studied diurnal changes in mean arterial pressure (MAP), heart rate (HR) and body temperature (Tb) during wake (W), non-rapid eye movement sleep (NREMS) and REM sleep (REMS) in the rat. Although HR and Tb show a similar sinusoidal diurnal variation during all vigilance states, the diurnal profile for the MAP is vigilance-state dependent. During W, MAP values are higher during the dark phase, during NREMS, no significant diurnal change is seen, and during REMS, the MAP exhibits a reversed diurnal change, being higher during the light phase. The low frequency component (0.25 - 0.725 Hz) in the power spectral density of the blood pressure, and index of sympathetic activity, is also higher during the light phase than the dark phase in REMS. The present findings suggest that diurnal changes in MAP in the rat result from the wake rhythm, and that the mechanism for the diurnal control of MAP may be different from that for HR or Tb.

Animals↗

PubMed1997

Sleep characteristics of Japanese working men who score alexithymic on the Toronto Alexithymia Scale.

This study examined the relationship of sleep characteristics including insomnia with scores on alexithymia in a sample of 171 Japanese working men. Levels of nonrestorative sleep and daytime sleepiness reported on a sleep questionnaire were significantly associated with scores on Depression and Confusion on the Profile of Mood States for Japanese men who had a high mean score on the Toronto Alexithymia Scale.

Adaptation, Psychological↗

PubMed1997

Mothers' low care in the development of alexithymia: a preliminary study in Japanese college students.

We examined the influences of perceived parental bonding on scores on alexithymia in a sample of 232 college students. Ratings on mothers' care, a scale of the Parental Bonding Inventory were significantly and negatively correlated with scores on the Toronto Alexithymia Scale, and also with ratings on Difficulty Describing Feelings but not Difficulty Identifying Feelings and Externally Oriented Thinking. These results were replicated in another sample of 156 college students. Although our findings were based on simple correlations, they suggest that perceived mothers' low care is related to adults' scores on alexithymia, in particular, the construct, Difficulty Describing Feelings.

Adolescent↗