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Y L Murashima

Publications and source records attributed to Y L Murashima.

At least 19 recordsLinked to original sources
PubMed1998

Antiepileptic effects of allopurinol on EL mice are associated with changes in SOD isoenzyme activities.

We have investigated the potential antiepileptic action of superoxide dismutase (SOD) activities in the brain of the epileptic mutant EL mouse. EL mice which experienced frequent seizures (EL[s]) had abnormally low levels of SOD isoenzyme activity in the hippocampal area. Once epileptogenicity was established in these animals, activity of cyanide-sensitive Cu,Zn-SOD was maintained at significantly lower levels than in control mice. However, cyanide-insensitive Mn-SOD activity was not different from non-epileptic controls. In EL mice which had not experienced seizure provoking stimulations and exhibited no seizures (EL[ns]) there was moderately lower levels of SOD isoenzyme activities compared to controls. In spite of the low level of Cu,Zn-SOD activity in EL[s] mice, the Cu,Zn-SOD protein content was high in the hippocampus of these animals, suggesting that inactive Cu,Zn-SOD might be induced during development. After allopurinol (ALP) was given orally to EL[s] mice, Cu,Zn-SOD activities increased dramatically in the hippocampus and seizure activity was decreased. Even after 48 h, when antiepileptic action of ALP was lost, the SOD activity was maintained at the high level associated with initial ALP administration. EL[s] mice also showed DNA fragmentation in the hippocampal CA1 region and the parietal cortex, detected with in situ terminal transferase-mediated dUTP nick labeling with the aid of alkaliphosphatase or peroxidase. The degree of DNA fragmentation was less severe in EL[ns] mice. We propose that abnormalities in region specific Cu,Zn-SOD isoenzyme activity might produce free radicals, leading to DNA fragmentations and cell loss. This might contribute to hippocampal epileptogenesis in EL mice.

Allopurinol↗
PubMed1996

Developmental and seizure-related regional differences in immediate early gene expression and GABAergic abnormalities in the brain of EL mice.

To examine the hypothesized role of the immediate early gene (IEG) response in synaptic plasticity and in epileptogenesis, we studied the spatial specificity of the expression of IEG in EL mice, a well known mutant model of epilepsy. Also to examine the 'GABA hypothesis' in epilepsy, GABA concentration and GAD activity was determined in micro brain regions (10-300 ng) of EL mice related to the focus in the parietal cortex and the hippocampus. We found that the IEG expression after seizures is not related to the seizure pattern, but to the seizure history, seizure threshold and development of EL[s]. Even in the interictal period, EL mice with long seizure histories and very low seizure thresholds demonstrate IEG expression continuously. This is probably strengthened by repeated seizures. The IEG expression site is however located in the hippocampal CA1, which is the final terminal of various inputs from other areas of the limbic system. It is proposed that the continuous expression of IEGs might play a different role from that of transiently expressed IEGs. Developmentally, the site of IEG expression shifted from one site to another in a very similar manner as in the IEG expression with propagation of paroxysmal discharges in each seizure, and the three-dimensional expression area was gradually expanded, suggesting a change in the regional active site during epileptogenesis. These lines of evidence suggest that during development as well as repetitive seizures, frequent expressions of IEGs and syntheses of Fos and Zif proteins might facilitate synaptic conductivity involved in epileptogenesis. The sites of abnormal GABA concentrations and GAD activities were almost the same in the parietal cortex, around Sidman atlas coronal section No. 300 and in the hippocampal CA1 pyramidal cells as the spatio-temporal specific IEG expression sites. These findings strongly suggest that IEG expression and abnormal GABAergic functions are involved in epileptogenesis in EL mice.

Animals↗
PubMed1994

Alcohol consumption and insomnia in a sample of Japanese alcoholics.

The amount of ethanol consumed by chronic alcoholics in a Japanese slum area with persistent insomnia (n = 40) and those without it (n = 40) was compared using a questionnaire. For both groups, the present habitual consumption (PHC) of ethanol per day was most frequently between 60 g and 150 g and no difference was observed between the two groups. In contrast, the maximum habitual consumption (MHC) of ethanol per day throughout the alcoholic history was found to be greater for the insomnia patients than the non-insomniacs (p < 0.001). No difference between the groups was found in the kind of alcoholic drink consumed, with sake (Japanese rice wine) being the most popular in both groups. The results suggest that persistent insomnia in alcoholics is related to excessive alcohol intake and persists even when drinking levels have fallen.

Adult↗
PubMed1990

gamma-Aminobutyric acid system in developing and degenerating mouse retina.

Freeze-dried sections (14 microns thick) of retinal layers were prepared from mice with retinal degeneration (C3H strain) and control mice (C57BL strain). The weighed sections (2-30 ng dry weight) were analyzed using our microassay methods. In the control retina, gamma-aminobutyric acid (GABA) concentration and glutamate decarboxylase (GAD) activity, on a dry weight basis, increased from birth to 9 weeks of age and decreased slightly at 20 weeks. In the degenerated retina, the levels of GABA and GAD activity were higher at birth than in the control retina, and continued to increase until 20 weeks of age, at which time the GAD activity reached a markedly high level. This increase was found when the total GABA and GAD levels per retina were determined. In the normal retinal layers, GABA and GAD were confined primarily to the inner plexiform layer. In the degenerated retina, GAD activity gradually increased in the inner layers during postnatal development, but by 20 weeks the increase was most prominent in the inner part of inner nuclear layer and in the outer part of inner plexiform layer. GABA transaminase activity and its distribution were not much different in both normal and degenerated retinas during development.

Animals↗
PubMed1987

GABA concentration and GAD activity levels in normal and degenerated retinas from mice.

Freeze-dried sections (14 microns thick) were prepared from mice with normal (C57BL strain) and degenerated (C3H strain) retinas. GABA concentration and GAD activity were determined in the microsamples (1.8-20 ng dry weight) of retinal layers and sublayers, using an enzymatic amplication reaction, NADP cycling. GABA was distributed over all layers of normal retina with a broad concentration peak covering both inner nuclear and plexiform layers. In contrast, GAD activity was mostly localized in the inner plexiform layer. GABA concentration was similar in one-fourth of the sublayers of each inner nuclear or plexiform layer. GAD activity was highest in the innermost sublayer of the inner nuclear layer. An increasing gradient of GAD activity was present in the inward direction in the inner plexiform layer. In the degenerated retina, lacking in photoreceptors, the inner nuclear and plexiform layers remained, and GABA and GAD levels in these layers were similar to those in normal retina.

Animals↗
PubMed1986

Distribution of gamma-aminobutyric acid and glutamate decarboxylase in the layers of rat oviduct.

An enzymatic microassay method for glutamate decarboxylase (GAD) and gamma-aminobutyric acid (GABA) was improved to yield a high sensitivity and a low blank. The 20-microns thick freeze-dried sections (0.2-1.5 micrograms dry weight) were prepared from the oviduct and ovary of rat. The analysis of these microsamples by the improved method showed that, contrary to the previous observations, the rat ovary is devoid of GAD activity and contains a trace amount of GABA. Both are present abundantly in the oviduct. In the oviduct mucosa, significant GAD activity was found in the estrous phase, whereas the activity was nearly null during other phases of the estrous cycle. GABA concentration in the oviduct mucosa was 10-fold higher than in the cerebral cortex; its variation during the estrous cycle was not remarkable. In the muscle layer of oviduct, GAD activity had a low peak in the estrous phase and GABA concentration was almost constant during the estrous cycle. The denervation experiment showed that GAD is present in the nerve terminals innervating the oviduct.

Animals↗
PubMed1985

Glutamate decarboxylase activities in single vertebrate neurons.

An enzymatic microassay method for glutamate decarboxylase (GAD) and gamma-aminobutyric acid (GABA) was improved to a degree yielding high sensitivity and low blank. Single cell bodies of anterior horn cells and dorsal root ganglion cells were dissected out from the freeze-dried sections of rabbit and chicken spinal cords and Purkinje cell bodies from those of rabbit cerebellum. A minute amount of GABA, present in single neurons or synthesized by GAD in single neurons, was enzymatically converted to NADPH. The NADPH was amplified 10,000-350,000-fold and measured, using an enzymatic amplification reaction (NADP cycling). GAD was contained in all Purkinje cell bodies and its average activity was four- to fivefold higher than those of the molecular and granular layers of rabbit cerebellum. The GABA concentration was threefold higher in Purkinje cell bodies than in these layers. GAD activity, at a level similar to that in the cerebellar layers, was found in almost all the cell bodies of anterior horn cells from rabbit and chicken. GABA was detected in 40% of rabbit neurons and not in chicken neurons. Dorsal root ganglion cells from both species contained no measurable GAD or GABA.

Animals↗