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Biomedical subjects

M Tohyama

Publications and source records attributed to M Tohyama.

At least 235 records · Page 13Linked to original sources
PubMed1993

Distribution of GAP-43 (B50/F1) mRNA in the adult rat brain by in situ hybridization using an alkaline phosphatase labeled probe.

GAP-43 (B-50,F1, pp46) is a calmodulin binding protein which is specific to the nervous system and also a substrate for the protein kinase C. Furthermore an enrichment of this protein in the growth cone and developmental brain indicate that this protein is related to nerve development, regeneration, and outgrowth. While its level dramatically decreases after the completion of synaptogenesis, the protein is still to some extent continuously expressed in certain regions of the mature brain. In order to clarify GAP-43 localization in mature normal rats, we investigated the distribution of GAP-43 mRNA in the rat central nervous system by using a non-radioisotopic in situ hybridization histochemistry. This method demonstrated GAP-43 mRNA expressing cells with high resolution. GAP-43 mRNA was more abundant in the forebrain than in the lower brainstem. Intense hybridization signal was observed in the mitral cells of olfactory bulb, cerebral cortex, CA3 region of hippocampus, diagonal band, substantia nigra, raphe nuclei, locus coeruleus, and dorsal motor nucleus of vagus. Weak to moderate hybridization signals were also widely expressed in thalamus, hypothalamus, and midbrain. Moreover, most noradrenergic, adrenergic, serotonergic, histaminergic, and caudal part of dopaminergic cells exhibited an intense GAP-43 mRNA signal. Thus, GAP-43 mRNA is abundantly expressed under normal conditions in the brain and may play an important physiological role particularly in the forebrain and in monoaminergic neurons supporting the findings that GAP-43 could be implicated in plasticity and monoamine release.

Alkaline Phosphatase↗
PubMed1993

Distribution of the substance P receptor (NK-1 receptor) in the central nervous system.

The overall distribution of mRNA for the substance P receptor (NK-1) was investigated in the rat brain by in situ hybridization histochemistry using synthetic oligonucleotide probes. The NK-1 positive cells were distributed throughout the brain. Among the positive cells an intense hybridization signal was observed in the basal ganglia and the dorsal tegmental areas. In the hippocampus, hypothalamus, midbrain, and medulla oblongata, weak to moderate positive signal were recorded in various areas. Comparing our results with those of previous workers on the localization of substance P using both immunohistochemistry and in situ hybridization various relationships between the ligand and its receptor localization were characterized. Generally the areas containing the abundant substance P immunoreactive (SP-IR) terminals were associated with NK-1 mRNA positive cells, some examples of this can be seen in the medial amygdaloid nucleus, the locus coeruleus, and the dorsal raphe nucleus. Contrary to these matched areas, we could not detect NK-1 mRNA positive cells in the substantia nigra, where there is a strong projection from the caudate putamen containing the substance P. Similarly the substantia gelatinosa in the trigeminal tract nucleus and the dorsal horn of the spinal cord where numerous SP-IR fibers are located, did not show abundant NK-1 mRNA positive cells. Only a few weakly labeled positive cells could be found.

Animals↗
PubMed1993

Region-specific expression of subunits of ionotropic glutamate receptors (AMPA-type, KA-type and NMDA receptors) in the rat spinal cord with special reference to nociception.

The present study attempted to explore the gene expression of the subunits (GluR1-4) of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type receptor, subunit (GluR5) of kainic acid (KA)-type receptor, NR1 [a subunit of N-methyl-D-aspartate (NMDA) receptors] and the possible glutamate-binding subunit of an NMDA receptor complex in the dorsal horn of the rat spinal cords using in situ hybridization histochemistry. These results were compared with those of the spinal motor neurons. Expression of the subunits of the AMPA-type receptor was also examined at the protein level using immunocytochemistry, with reference to the motor neurons. Although all the four subunits of the AMPA-type receptor were expressed throughout the dorsal horn, the pattern of expression was different according to the dorsal horn region and to the subunits. GluR2 showed the strongest expression in the dorsal horn. Huge numbers of strongly labelled cells formed a dense collection in lamina II and superficial parts of lamina III. Many neurons in lamina II and superficial parts of lamina III expressed GluR1 moderately. Scattered neurons moderately expressing GluR3 were also seen in these regions, while the expression of GluR4 was very low. Labelling of the dorsal horn neurons by the GluR5 probe was low, and NR1 probe and a glutamate-binding subunit of an NMDA receptor complex probe labelled them diffusely with low to moderate intensity. These findings show a close relationship between the glutamergic nociceptive primary afferent system and AMPA-type receptors in which GluR2 is especially highly expressed. The present study further showed that the expression pattern of the glutamate receptors in the spinal sensory neurons differs considerably from that of spinal motor neurons. Motor neurons very strongly express GluR3 and 4, while the expression of GluR2 and GluR1 is moderate and low, respectively. Expression of GluR5 is also low in the motor neurons. However, expression of NR1 and the glutamate-binding subunit of an NMDA receptor complex is very strong. These findings indicate that the subunit composition of the AMPA-type receptors regulating motor neurons is different from that of the AMPA-type receptors in the spinal sensory neurons, and that there are at least two kinds of glutamergic systems which regulate motor neurons: via AMPA-type receptors and via NMDA receptors.

Animals↗
PubMed1993

The differential expression patterns of messenger RNAs encoding non-N-methyl-D-aspartate glutamate receptor subunits (GluR1-4) in the rat brain.

The messenger RNA expression of non-N-methyl-D-aspartate glutamate receptor subunits (GluR1-4), considered alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid type, was investigated in rat brain by in situ hybridization histochemistry using oligonucleotide probes specific to each subunit sequence. GluR1-4 subunit messenger RNAs were expressed widely and abundantly throughout the CNS. However, the combination of expression pattern varied notably according to location. GluR2 messenger RNA was expressed most strongly and widely, with most areas except the Bergmann glia containing this messenger RNA. GluR4 messenger RNA was also present widely, although the expression level was low. However, we observed many areas which lacked or expressed very little GluR1 messenger RNA, such as some nuclei in the general motor system and auditory system. In addition, some nuclei in the hypothalamus and general somatosensory system lacked or expressed very little GluR3 messenger RNA. These results suggest that in the rat CNS non-N-methyl-D-aspartate receptors varied their composition according to the area where they were expressed, and that the combination pattern might be related to the functional role of neurons.

Animals↗
PubMed1993

Stress-induced c-fos expression in the rat brain: activation mechanism of sympathetic pathway.

To clarify which brain regions are activated by stress, we used expression of the proto-oncogene, c-fos, as a marker. An increased number of neurons expressing Fos-like immunoreactivity in their nuclei was observed in discrete brain regions, such as the lateral septum, midline nuclei of the thalamus, paraventricular hypothalamic nucleus, brain stem catecholaminergic, and serotonergic neurons, in response to pain or immobilization stress. Distribution patterns of Fos-like immunoreactive neurons were quite similar in animals subjected to pain or immobilization. Whether or not neurons projecting to the spinal cord to activate the sympathetic pathway express Fos-like immunoreactivity was examined by means of fluorescent double-labeling using fluoro-gold (FG) as a tracer. In the PVH, Fos-immunoreactive neurons were localized in the dorsal medial parvocellular part, although those projecting to the spinal cord were localized dorsally and ventrally. Less than 1% of Fos-positive neurons in this nucleus was colocalized with FG. Among fos-like immunoreactive catecholaminergic and serotonergic neurons in the brain stem, those in the A5 region and raphe pallidus projected to the spinal cord.

Animals↗
PubMed1993

Differential effects on substance P immunoreactivity in rat suprachiasmatic and olivary pretectal nuclei.

We examined the effects of constant dark or constant light on substance P (SP) and/or neuropeptide Y (NPY) immunoreactive fibres in the rat suprachiasmatic nucleus (SCN) and olivary pretectal nucleus (OPT) by immunohistochemistry. After constant dark, SP immunoreactive fibres and terminals decreased slightly in the SCN, while they increased markedly in the OPT. After constant light, they increased markedly in the SCN, but were little changed in the OPT. NPY immunoreactive fibres and terminals in the SCN decreased slightly after after constant light, but there were no effects on these fibres after constant dark. These findings suggest that SP immunoreactive fibres are involved in mediating illumination discrimination in the SCN and/or OPT.

Animals↗
PubMed1993

Immunoadsorption plasmapheresis for severe generalised myasthenia gravis.

Two patients with severe generalised myasthenia gravis of childhood were successfully treated with immunoadsorption plasmapheresis. One patient was a 5 year old girl and the other was a 12 year old girl. A dramatic improvement in bulbar symptoms and generalised muscle weakness was achieved without any side effects. Plasma exchange may also yield clinical improvement for myasthenia gravis, but the treatment is accompanied by the risk of viral infections and hypersensitivity reactions. Immunoadsorption plasmapheresis is an effective treatment for severe generalised myasthenia gravis of childhood and is superior to plasma exchange with respect to safety.

Child↗
PubMed1993

Localization of oxytocin receptor messenger ribonucleic acid in the rat brain.

The expression of oxytocin receptor (OT-R) mRNA in the rat central nervous system was examined by in situ hybridization histochemistry using cRNA probe. Wide distribution of cells expressing OT-R mRNA was observed not only in the hypothalamus, but also in other regions. There were high levels of OT-R mRNA in the anterior olfactory nuclei, tenia tecta, olfactory tubercle, rostral most region of the frontal cortex, piriform cortex, layers 2 and 3 of the neocortex, bed nucleus of the stria terminalis, anterior medial preoptic nucleus (AV3V region), magnocellular preoptic nucleus, supraoptic nucleus, paraventricular hypothalamic nucleus, retrochiasmatic nucleus, ventromedial hypothalamic nucleus, paraventricular thalamic nucleus, central amygdaloid nucleus, medial amygdaloid nucleus, posterior cortical amygdaloid nucleus, amygdalohippocampal area, subiculum, prepositus hypoglossal nucleus, and dorsal motor nucleus of vagus. In most regions of the brain, our findings concurred with those obtained by receptor binding autoradiography using a ligand specific to OT. However, in the inferior olive nucleus, OT-R mRNA was not detected despite an abundance of binding sites showed by receptor binding autography. Despite this discrepancy OT appears to have central nervous system functions in addition to its hormonal functions.

Animals↗
PubMed1993

GAP-43 mRNA expression in facial motoneurons during regeneration: in situ hybridization histochemistry study using an alkaline phosphatase-labelled probe.

By means of in situ hybridization histochemistry using an alkaline phosphatase-labelled probe, we found an increase of mRNA for the growth-associated protein GAP-43 in rat facial motoneurons following axotomy of the facial nerve. After nerve resection, the increased level of GAP-43 mRNA was maintained for at least 8 weeks, while it returned to almost undetectable levels by 8 weeks after nerve crush injury. Thus, expression of GAP-43 mRNA in motor neurons paralleled the process of axonal regeneration. However, the increase of GAP-43 mRNA after resection was more pronounced than after crushing, in this way being different from the pattern of low-affinity nerve growth factor receptor mRNA expression.

Alkaline Phosphatase↗
PubMed1992

Histamine-caused itch induces Fos-like immunoreactivity in dorsal horn neurons: effect of morphine pretreatment.

It is well known that cutaneous pain causes c-fos gene expression in the dorsal horn neurons. The present study examined whether or not an itching sensation had the same effect on these neurons. In order to produce an itching sensation, cotton balls soaked in histamine solutions of different concentrations were applied to the lower limbs of rats and then the treated area was scratched with the tip of a pair of forceps. After 2 h, the number of neurons showing Fos-like immunoreactivity was significantly increased in a dose-dependent manner in the ipsilateral dorsal horn when compared to saline-treated and scratched controls. When scratching with the forceps was omitted, the number of these neurons was reduced to one-third, but was still significantly higher than in controls treated only with saline. Expression of Fos-like immunoreactivity in these animals was markedly reduced by morphine pretreatment (10 mg/kg, i.p.), suggesting that the transmission of both itch and pain is blocked by morphine.

Animals↗
PubMed1992

Axonal flow blockade induces alpha-CGRP mRNA expression in rat motoneurons.

Axonal flow of motoneurons was blocked in the sciatic nerve by the application of vinblastine at a low concentration (100 microM) not considered likely to cause axonal degeneration. The number of motoneurons expressing alpha-calcitonin gene-related peptide (CGRP) mRNA was significantly increased by vinblastine application, while the expression of beta-CGRP mRNA was not influenced. These findings suggest that the synthesis of these two peptides is differentially regulated and that alpha-CGRP mRNA is possibly down-regulated by unknown factor(s) which normally undergo retrograde transport from the periphery.

Animals↗
PubMed1992

Regional distribution of cells expressing glycine receptor alpha 2 subunit mRNA in the rat brain.

The alpha 2 subunit of the glycine receptor is expressed transiently in the rat brain during early development suggesting that this subunit may be replaced by the alpha 1 subunit in the adult brain. The expression of glycine receptor alpha 2 subunit mRNA was investigated in the 7-day-old rat brain by in situ hybridization histochemistry using oligonucleotide probes specific for this subunit. Neurons expressing alpha 2 subunit mRNA were found to be widely and abundantly distributed throughout brain. We compared the distribution of neurons expressing alpha 2 subunit mRNA with that of neurons expressing alpha 1 or beta subunit mRNA. In the lower brainstem, the location of the neurons expressing alpha 2 subunit mRNA was very similar to that of the neurons with alpha 1 or beta subunit mRNA. Neurons expressing beta subunit mRNA were widespread and numerous in the forebrain, where neurons with alpha 1 subunit mRNA were uncommon. The locations of the neurons labeled by the alpha 2 probe were very similar to those of the cells labeled by the beta probe. These findings suggest that the alpha 2 subunit is not only expressed by immature neurons containing the alpha 1 subunit, but is also common to most immature neurons having the glycine receptor. However, it should be noted that several neurons contained beta and/or alpha 1 subunit mRNA but lacked alpha 2 subunit mRNA, suggesting that the glycine receptor is heterogeneous in its composition during brain development.

Animals↗
PubMed1992

Co-localized but target-unrelated expression of vasoactive intestinal polypeptide and galanin in rat dorsal root ganglion neurons after peripheral nerve crush injury.

Expression of vasoactive intestinal polypeptide (VIP) and galanin in dorsal root ganglion (DRG) neurons is known to be induced by peripheral nerve injury. We investigated (1) whether VIP and galanin were co-expressed by DRG neurons and (2) whether such neurons innervated specified peripheral targets (visceral, cutaneous or muscular). An antibody to the 200 kDa neurofilament subunit (NF200) was used as a marker for large type-A cells in the DRG. VIP and galanin were respectively observed in 22% and 67% of DRG neurons at the L5 spinal level after crushing of the sciatic nerve. Most VIP-containing neurons were small type-B cells (about 90%) and approximately 95% of VIP-containing neurons also showed galanin-like immunoreactivity. Galanin was expressed by both large type-A and small type-B cells. Immunocytochemistry combined with a retrograde tracer revealed that about 70-80% of the small type-B cells in each sensory division displayed VIP-like immunoreactivity, and that most of the tracer-labeled neurons also expressed galanin. These findings suggest that the expression VIP and/or galanin in response to peripheral nerve crush injury is a property common to visceral, cutaneous and muscular sensory neurons.

Animals↗
PubMed1992

Axonal blockade induces the expression of vasoactive intestinal polypeptide and galanin in rat dorsal root ganglion neurons.

Nerve growth factor (NGF) undergoes retrograde transport from peripheral target organs, and has been recently reported to regulate the production of some neuropeptides in dorsal root ganglion (DRG) neurons. Therefore, to ascertain whether or not the expression of calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), and galanin was regulated by the retrograde transport of factors such as NGF, we carried out an immunocytochemical analysis using vinblastine as an axonal transport blocker and a monoclonal antibody to the NGF receptor (NGFR) as a marker of NGF-responsive neurons. The percentage of CGRP-containing DRG neurons (L5) was decreased by sciatic nerve transection or by the application of higher doses of vinblastine (0.3-0.6 mM) to the sciatic nerve. VIP and galanin were expressed in some DRG neurons after the application of a low dose of vinblastine (0.15 mM), which can block axonal flow without causing neuronal damage. The expression of these peptides was not affected by dorsal rhizotomy. About 70% of the CGRP-containing neurons also expressed NGFR, while most of the VIP-containing or galanin-containing neurons lacked NGFR. These findings indicate that the depletion of peripheral target-derived neurotrophic factor(s) other than NGF by axonal blockade may induce the gene expression of VIP and galanin.

Animals↗
PubMed1992

Nasal mucosa sensitization with toluene diisocyanate (TDI) increases preprotachykinin A (PPTA) and preproCGRP mRNAs in guinea pig trigeminal ganglion neurons.

Toluene diisocyanate (TDI) induces respiratory allergy in mammals. Using immunohistochemistry and in situ hybridization histochemistry, the present study examined effects of nasal mucosa sensitization by TDI on the immunoreactivity for substance P (SP) and calcitonin gene-related peptide (CGRP) and on the expression of their mRNAs in guinea pig trigeminal ganglion and their terminals. Single intranasal application of TDI (acute experiment) did not induce nasal allergy-like behaviours and failed to cause changes of SP and CGRP immunoreactivity and in the expression of preprotachykinin A (PPTA) mRNA and preproCGRP mRNA coding for SP and CGRP respectively in the trigeminal ganglion neurons. However, repeated application of TDI (chronic experiment) caused a dramatic increase of SP and CGRP immunoreactivity in peripheral neurites of sensory nerves in the nasal mucosa but a slight increase in the spinal trigeminal nucleus, a decrease of the same immunoreactivities in the cell bodies of the trigeminal ganglion neurons, and an increase of the expression of PPTA and preproCGRP mRNA in the same neurons. These findings suggest that chronic exposure of the nasal mucosa to TDI apparently causes enhancement of both the biosynthesis of SP and CGRP and their axonal transport in the trigeminal system.

Animals↗
PubMed1992

Co-localization of basic fibroblast growth factor-like immunoreactivity and its receptor mRNA in the rat spinal cord and the dorsal root ganglion.

In the present study, we examined the localizations of basic fibroblast growth factor-like immunoreactivity (bFGF-LI) and its receptor mRNA in the spinal cord and the dorsal root ganglion of the rat. Anti-bFGF peptide antibody and cRNA probe were employed to visualize the localizations of bFGF-LI and FGF receptor (FGF-R) mRNA, respectively. In the spinal cord, we observed that a number of neurons including the motor neurons and interneurons were positive for both substances. In the dorsal root ganglion (DRG), the large neurons preferentially showed co-localization of bFGF-LI and FGF-R mRNA, while the small neurons were not always positive for both. Given the fact that FGF-R is a membrane-spanning protein, these findings suggest the following two possibilities: (1) bFGF acts on the neurons of the spinal cord and the DRG in an autocrine and/or paracrine manner; (2) FGF-R mRNA-positive neurons take up bFGF from innervating neurons and/or surrounding glias in a receptor-mediated fashion.

Animals↗