Biomedical subjects

N Mizuno

Publications and source records attributed to N Mizuno.

At least 181 records · Page 10Linked to original sources

PubMed1993

Distribution of the mRNA for a metabotropic glutamate receptor (mGluR3) in the rat brain: an in situ hybridization study.

Distribution of the mRNA for a metabotropic glutamate receptor, mGluR3, which is coupled to the inhibitory cAMP cascade, was examined in the central nervous system of the adult albino rat by in situ hybridization. The hybridization signals of mGluR3 were detected not only on neuronal cells but also on many glial cells throughout the brain and spinal cord. In the neuronal cells, prominent expression of mGluR3 mRNA was seen in the thalamic reticular nucleus. Moderately labeled neurons were seen in the anterior olfactory nucleus, cerebral neo- and mesocortical regions, lateral amygdaloid nucleus, ventral part of the basolateral amygdaloid nucleus, dorsal endopiriform nucleus, supraoptic nucleus, superficial layers of the superior colliculus, inferior colliculus, interpeduncular nucleus, superior olivary nuclei, and Golgi cells in the cerebellar cortex. Weakly labeled neurons were observed in the striatum, nucleus accumbens, ventral pallidum, globus pallidus, entopeduncular nucleus, lateral hypothalamic area, hypothalamic paraventricular nucleus, medial habenular nucleus, anterior pretectal nucleus, Barrington's nucleus, Nucleus O, paragenual nucleus, trigeminal sensory complex, cochlear nuclei, dorsal motor nucleus of the trigeminal nerve, dorsal cap of the inferior olive, spinal dorsal horn, and lamina X of the spinal cord. The stellate cells in the cerebellar cortex, and neurons in the deep cerebellar nuclei were also labeled weakly. The granule cell layer of the dentate gyrus, as a whole, appeared to be labeled intensely, but each of the granule cells was labeled only weakly. No significant labeling was detected in the mitral and tufted cells in the olfactory bulb, hippocampal pyramidal cells, Purkinje and granule cells in the cerebellar cortex, or somatic motoneurons. The distribution of mGluR3 mRNA in particular neurons and glial cells indicates specific roles of mGluR3 in the glutamatergic system of the central nervous system.

Animals↗

PubMed1993

Ultrastructural demonstration of exocytosis of neurosecretory granules in the neurohypophysis of the frog Rana temporalia.

The release of neurosecretory granules by exocytosis was ultrastructurally observed in the neurohypophysis pars nervosa (posterior lobe) of the frog Rana temporalia with the tannic acid-Ringer fixation method. Electron microscopic analysis with the immunogold method revealed that many of putative neurosecretory granules displayed oxytocin-like immunoreactivity.

Animals↗

PubMed1993

Demonstration of habenular neurons which receive afferent fibers from the nucleus accumbens and send their axons to the midbrain periaqueductal gray.

After injecting Phaseolus vulgaris leucoagglutinin (PHA-L) and wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP), respectively, into the medial part of the nucleus accumbens (NA) and the midbrain periaqueductal gray including the dorsal raphe nucleus (PAG/DR) on one side of single rat brains, we observed that axon terminals labeled anterogradely with PHA-L made possible synaptic contact with neurons in the habenula (Hb) which were retrogradely labeled with WGA-HRP. These Hb neurons were distributed in the medial part of the lateral Hb. The results indicate that the medial part of the lateral Hb relays neuronal information from the medial part of the NA to the PAG/DR.

Animals↗

PubMed1993

The sites of origin of dopaminergic afferent fibers to the lateral habenular nucleus in the rat.

The lateral habenular nucleus of the rat contains a dense plexus of dopaminergic fibers, which are more marked in the medial part of the lateral habenular nucleus than in its lateral counterpart. Employing a combination of fluorescent retrograde axonal tracing with fluorogold and tyrosine hydroxylase immunofluorescence histochemistry, we investigated the distribution of cells of origin of the dopaminergic afferent fibers to the lateral habenular nucleus in the rat. The cells double-labeled with both fluorogold injected into the lateral habenular nucleus and tyrosine hydroxylase antisera were seen in a variety of fore- and midbrain regions, including the bed nucleus of the stria terminalis, medial preoptic area, periventricular, ventromedial, and dorsomedial hypothalamic nuclei, ventral tegmental area, interfascicular nucleus, substantia nigra pars compacta, ventrolateral division of the midbrain periaqueductal gray, and dorsal raphe nucleus. The double-labeled cells were located bilaterally with an ipsilateral predominance, and constituted approximately 10% of the total fluorogold-positive cell population. We have further observed by anterograde axonal tracing with Phaseolus vulgaris-leucoagglutinin that projection fibers arising from the sites of origin of the dopaminergic afferent fibers to the lateral habenular nucleus terminate mainly in the medial part of the lateral habenular nucleus, and to a lesser extent in its lateral counterpart. Thus, we have found in the present study that the dopaminergic neurons sending their axons to the lateral habenular nucleus are widely distributed in the A9, A10, A14, and A15 dopaminergic cell groups. Such dopaminergic neurons may exert regulatory influences upon many limbic-associated brain regions via the lateral habenular nucleus.

Afferent Pathways↗

PubMed1993

Molecular characterization of a novel retinal metabotropic glutamate receptor mGluR6 with a high agonist selectivity for L-2-amino-4-phosphonobutyrate.

A cDNA clone for a new metabotropic glutamate receptor, termed mGluR6, was isolated from a rat retinal cDNA library by cross-hybridization with the previously isolated cDNA clone for a metabotropic glutamate receptor. The cloned mGluR6 subtype consists of 871 amino acid residues and exhibits a structural architecture common to the metabotropic receptor family, possessing a large extracellular domain preceding the seven putative membrane-spanning domains. mGluR6 shows the highest sequence similarity to mGluR4 among the metabotropic receptor subtypes and inhibits the forskolin-stimulated cyclic AMP accumulation in Chinese hamster ovary cells transfected with the cloned cDNA. mGluR6 potently reacts with L-2-amino-4-phosphonobutyrate (L-AP4) and L-serine-O-phosphate, and the potencies of these compounds are one order of magnitude greater than that of L-glutamate. Blot and in situ hybridization analyses indicated that mGluR6 mRNA is restrictedly expressed in the inner nuclear layer of the retina where ON-bipolar cells are distributed. The metabotropic receptor that responds strongly to L-AP4 and L-serine-O-phosphate in ON-bipolar cells is known to mediate glutamate synaptic transmission between photoreceptor cells and ON-bipolar cells. On the basis of the agonist selectivity of mGluR6 and its specific expression in retinal cells, the physiological role of this receptor subtype in the visual system is discussed.

Amino Acid Sequence↗

PubMed1993

Identification of premotor interneurons which project bilaterally to the trigeminal motor, facial or hypoglossal nuclei: a fluorescent retrograde double-labeling study in the rat.

With the aid of a fluorescent retrograde double-labeling technique, we examined in the rat the distribution of single neurons which project bilaterally to one of the orofacial motor nuclei (the trigeminal motor, facial and hypoglossal nuclei) by branching axons. The results suggested that premotor interneurons were distributed most frequently in the medial part of the parvicellular reticular nucleus; such neurons were further scattered in the other regions of the medullary reticular formation, in the regions around the trigeminal motor nucleus, in the parabrachial area, and in the mesencephalic reticular formation.

Animals↗

PubMed1993

Collateral projections of single neurons in the periaqueductal gray and dorsal raphe nucleus to both the trigeminal sensory complex and spinal cord in the rat.

After injecting Diamidino yellow (DY) and Fast blue (FB), respectively, into the trigeminal sensory complex and lumbar cord segments, neurons were doubly labeled retrogradely with both DY and FB in the periaqueductal gray (PAG) and dorsal raphe nucleus (DR). The fluorescent retrograde double-labeling method combined with serotonin (5HT) immunofluorescence histochemistry revealed that more than 70% of the doubly labeled PAG/DR neurons showed 5HT-like immunoreactivity (5HT-LI). These 5HT-LI PAG/DR neurons may modulate nociceptors in the trigeminal sensory complex and spinal cord by sending axon collaterals to these regions.

Animals↗

PubMed1993

Immunocytochemical localization of rat substance P receptor in the striatum.

A trp E fusion protein containing a C-terminal portion of the rat substance P receptor (SPR) was expressed in bacteria and used to produce an antibody. The antibody specifically reacted with SPR expressed in a mammalian cell line and rat striatum. Light and electron microscope analyses of the rat striatum revealed intense SPR-like immunoreactivity in neuronal somata and dendrites. These immunoreactive neurons constituted approximately 3% of the total population of striatal neurons; they were putative interneurons of large and medium-sized aspiny type.

Animals↗

PubMed1993

Bilateral projections of single retinal ganglion cells to the lateral geniculate nuclei and superior colliculi in the albino rat.

Employing fluorescent retrograde double/triple labeling, we investigated bilateral projections of single retinal ganglion cells to the lateral geniculate nuclei (LGN) and superior colliculi (SC) in the albino rat. After separate injections of Fast Blue (FB) and Diamidino Yellow (DY), respectively, into the right and left LGN, a large number of retrogradely-labeled cells were distributed all over the retina contralateral to each injection. Ipsilaterally projecting ganglion cells, which were labeled with one tracer injected into the LGN, were found predominantly in the lower-temporal retinal region; approximately 56% (120-140 cells per retina) of them were further labeled with the other tracer injected into the contralateral LGN. The vast majority of these double-labeled cells were of large type (more than 20 microns in diameter). Similar findings were obtained after separate injections of FB and DY, respectively, into the right and left SC, or respectively, into the right SC and left LGN. After separate injections of FB, DY and rhodamine-B-isothiocyanate, respectively, into the bilateral LGN and unilateral SC, or respectively, into the unilateral LGN and bilateral SC, a number of cells triple-labeled with all tracers were localized in the lower-temporal retinal region; most of them were of large type. Thus, the bilateral projections from the lower-temporal retinal region representing binocular vision in the rat are indicated to be achieved not only by separate populations of ganglion cells each exclusively serving one side of the brain, but also by axon collaterals from single ganglion cells; the ganglion cells projecting bilaterally to the LGN or/and SC are primarily of large type corresponding probably to the Y cell in the cat retina.

Amidines↗

PubMed1993

Demonstration of axon terminals of projection fibers from the periaqueductal gray onto neurons in the nucleus raphe magnus which send their axons to the trigeminal sensory nuclei.

Axon terminals of projection fibers from the periaqueductal gray (PAG) onto neurons in the nucleus raphe magnus (NRM) sending their axons to the principal sensory trigeminal nucleus (Vp) or caudal spinal trigeminal nucleus (Vc) were demonstrated light microscopically: In the rats which were injected with Phaseolus vulgaris leucoagglutinin (PHA-L) and wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) respectively into the PAG and trigeminal sensory complex (Vp or Vc), presumed axon terminals labeled anterogradely with PHA-L appeared to make synaptic contacts with NRM neurons labeled retrogradely with WGA-HRP.

Animals↗

PubMed1993

Premotor neurons projecting simultaneously to two orofacial motor nuclei by sending their branched axons. A study with a fluorescent retrograde double-labeling technique in the rat.

Premotor neurons innervating simultaneously two of the trigeminal motor (Vm), facial (VII) and hypoglossal nuclei (XII) by sending their branched axons were demonstrated in the lower brain stem of the rat by means of a fluorescent retrograde double-labeling method with Fast Blue (FB) and Diamidino Yellow (DY). After injections of FB and DY, respectively, into the Vm and VII, into the Vm and XII, or into the VII and XII, the majority of neuronal cell bodies labeled doubly with FB and DY were distributed in the lateral tegmental field, especially its medial part in the medulla oblongata.

Amidines↗

PubMed1993

Collateral projections of single neurons in the nucleus raphe magnus to both the sensory trigeminal nuclei and spinal cord in the rat.

After injecting Diamidino yellow and Fast blue respectively into the sensory trigeminal nuclei and spinal cord, we observed doubly labeled cells in the nucleus raphe magnus (NRM). Combining the fluorescent retrograde double labeling with serotonin (5-HT) immunofluorescence histochemistry, we further found that about 30% of the doubly labeled NRM neurons showed 5-HT-like immunoreactivity (5-HT-LI). Such 5-HT-LI NRM neurons may modulate nociceptive activities simultaneously in the sensory trigeminal nuclei and spinal cord by sending axon collaterals to these regions.

Animals↗

PubMed1993

Molecular characterization of the family of the N-methyl-D-aspartate receptor subunits.

cDNA clones for four different N-methyl-D-aspartate (NMDA) receptor subunits (NMDAR2A-NMDAR2D) were isolated through polymerase chain reactions followed by molecular screening of a rat brain cDNA library. These subunits are only about 15% identical with the key subunit of the NMDA receptor (NMDAR1) but are highly homologous (approximately 50% homology) with one another. They also commonly possess large hydrophilic domains at both amino- and carboxyl-terminal sides of the four putative transmembrane segments. NMDAR2A and NMDAR2C expressed individually in Xenopus oocytes showed no electrophysiological response to agonists. However, these subunits in combined expression with NMDAR1 markedly potentiated the NMDAR1 activity and produced functional variability in the affinity of agonists, the effectiveness of antagonists, and the sensitivity to Mg2+ blockade. Thus, NMDAR1 is essential for the function of the NMDA receptor, and multiple NMDAR2 subunits potentiate and differentiate the function of the NMDA receptor by forming different heteromeric configurations with NMDAR1. Northern blotting and in situ hybridization analyses revealed that the expressions of individual mRNAs for the NMDAR2 subunits overlap in some brain regions but are also specialized in many other regions. This investigation demonstrates the anatomical and functional differences of the NMDAR2 subunits, which provide the molecular basis for the functional diversity of the NMDA receptor.

Amino Acid Sequence↗

PubMed1993

Collateral projections of trigeminal ganglion neurons to both the principal sensory trigeminal and the spinal trigeminal nuclei in the rat.

Employing a combination of fluorescent retrograde double labelling and immunofluorescence histochemistry for substance P (SP) and calcitonin gene-related peptide (CGRP), we examined collateral projections from single neurons in the trigeminal ganglion (TG) of the rat to both the principal sensory trigeminal nucleus (Vp) and the oral, interpolar or caudal subnuclei of the spinal trigeminal nucleus (Vo, Vi or Vc). In the rats that were unilaterally injected with fast blue (FB) into the Vp and with diamidino yellow (DY) into the Vo, Vi or Vc, neurons labelled with FB and/or DY were observed in the TG ipsilateral to the injections. Of the labelled TG neurons, about 2% were double labelled with both tracers in the rats that were injected with FB into the Vp and with DY into the Vo or Vi, and about 10% were double labelled in the rats that were injected with FB into the Vp and with DY into the Vc. The results indicate that TG neurons sending their axons to the Vp project, by way of axon collaterals, to the Vc more frequently than to the Vo or Vi. Some of the TG neurons double labelled with FB and DY exhibited SP- or CGRP-like immunoreactivity (LI): Of the TG neurons that were double labelled with FB injected into the Vp and with DY injected into the Vo, Vi or Vc, about 38%, 49% and 42%, respectively, displayed SP-LI, and about 54%, 58% and 59%, respectively, showed CGRP-LI.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗

PubMed1993

Laminar organization of the substantia nigra pars reticulata in the macaque monkey, with special reference to the caudato-nigro-tectal link.

A laminar organization of the substantia nigra pars reticulata (SNr) was revealed in the macaque monkey by using an semihorizontal section plane parallel to the long axis of the SNr in the frontal plane. After injecting horseradish peroxidase conjugated to wheat germ agglutinin into the caudate nucleus (Cd) or putamen, anterogradely labelled fibres and axon terminals in the SNr were observed to form parallel bands in the anteromedial-posterolateral direction. After injecting Fast Blue into the superior colliculus, a cluster of retrogradely labelled neuronal cell bodies also formed a single band arranged in the similar anteromedial-posterolateral direction. The cluster was observed along the anterolateral margin of the SNr. This SNr region containing nigrotectal neurons appeared to overlap with one of the bands containing terminals of striatonigral fibres arising from the body of the Cd. The caudato-nigro-tectal link via the anterolateral marginal area might be involved in the control of saccadic eye movements.

Animals↗

PubMed1993

The sites of origin of serotoninergic afferent fibers in the trigeminal motor, facial, and hypoglossal nuclei in the rat.

The sites of origin of serotoninergic afferents in the trigeminal motor (Vm), facial (VII), and hypoglossal nuclei (XII) were studied in the rat by fluorescent retrograde labeling with Fluoro-Gold, in combination with immunofluorescence histochemistry for serotonin (5-HT). The results indicated: (1) The nucleus raphe magnus, nucleus raphe pallidus, and nucleus raphe obscurus contained 5-HT neurons projecting to the Vm, VII or XII. (2) The nucleus raphe dorsalis sends 5-HT fibres to the Vm and VII, but not to the XII. (3) The gigantocellular reticular nucleus pars alpha contained 5-HT neurons projecting to the VII.

Afferent Pathways↗

PubMed1993

Direct projections from the midbrain periaqueductal gray and the dorsal raphe nucleus to the trigeminal sensory complex in the rat.

It is well known that analgesia can be produced by stimulation of the midbrain periaqueductal gray and dorsal raphe nucleus. This stimulation-produced analgesia may operate, at least partly, through direct projections to nociceptors in the primary sensory nuclei. In the present study, direct projections from the midbrain periaqueductal gray and dorsal raphe nucleus to the trigeminal sensory complex were studied in the rat. After injection of Phaseolus vulgaris leucoagglutinin into the periaqueductal gray or dorsal raphe nucleus, terminal labeling was found in the principal sensory trigeminal nucleus and the oral, interpolar and caudal subnuclei of the spinal trigeminal nucleus, bilaterally with an ipsilateral predominance. The terminal labeling was prominent in the ventrolateral parts of the trigeminal sensory complex; it was particularly marked in the principal sensory trigeminal nucleus and laminae I and III of the caudal subnucleus of the spinal trigeminal nucleus. After injection of cholera toxin B subunit into the principal sensory trigeminal nucleus or one of the subnuclei of the spinal trigeminal nucleus, retrogradely labeled cells were seen in the periaqueductal gray and dorsal raphe nucleus, bilaterally with an ipsilateral dominance. In the periaqueductal gray they were most often seen in the ventrolateral and dorsolateral subdivisions, but no particular topographic organization was detected in the distribution of retrogradely labeled neurons in the periaqueductal gray and dorsal raphe nucleus after tracer injection into each subdivision of the trigeminal sensory complex. After injections of Fast Blue and Diamidino Yellow, respectively, into the principal sensory trigeminal nucleus and the caudal subnucleus of the spinal trigeminal nucleus on one side of the brain, a number of doubly labeled neurons were found in the periaqueductal gray and dorsal raphe nucleus, bilaterally with an ipsilateral dominance. The results indicate that a considerable number of neurons in the periaqueductal gray and dorsal raphe nucleus send projection fibers to the trigeminal sensory complex, and that some of them send their axons to both the principal sensory trigeminal nucleus and the caudal subdivision of the spinal trigeminal nucleus by way of axon collaterals. These projections may subserve suppression of the activity of nociceptive neurons in the trigeminal system.

Amidines↗

PubMed1993

Distribution of the messenger RNA for a metabotropic glutamate receptor, mGluR2, in the central nervous system of the rat.

Distribution of the messenger RNA for a metabotropic glutamate receptor, mGluR2, which is coupled to the inhibitory cyclic AMP cascade, was investigated in the central nervous system of the adult rat by in situ hybridization. Transcripts of mGluR2 were specifically localized to neuronal cells of the brain. Although the hybridization signals were widely distributed in the brain, the most prominent expression of mGluR2 messenger RNA was seen in Golgi cells of the cerebellum. Marked expression of mGluR2 messenger RNA was further observed in the mitral cells of the accessory olfactory bulb, neurons in the external part of the anterior olfactory nucleus, and pyramidal neurons in the entorhinal and parasubicular cortical regions. The granule cells of the accessory olfactory bulb, and many pyramidal and non-pyramidal neurons in the neocortical, cingulate, retrosplenial and subicular cortices, were moderately labeled. All of the granule cells in the dentate gyrus were also labeled moderately, whereas no significant hybridization signals were detected in Ammon's horn. In the basal forebrain regions, moderately labeled neurons were distributed in the triangular septal nucleus, in the lateral, basolateral and basomedial amygdaloid nuclei, and in the medial mammillary nucleus. Weakly labeled neurons were sparsely scattered in the striatum, globus pallidus, ventral pallidum and claustrum. The subthalamic nucleus was also labeled weakly. No significant labeling was found in the entopeduncular nucleus and substantia nigra. In the thalamus, moderately labeled neurons were distributed in the anterodorsal, anteromedial, ventromedial, intralaminar and midline nuclei; the ventrolateral part of the anteroventral nucleus and the rostral pole of the ventrolateral nucleus also contained moderately labeled neurons. No significant labeling was found in the thalamic reticular, submedius, ventroposterior, lateral geniculate and medial geniculate nuclei. In the lower brainstem, labeling was generally weak. No significant hybridization signals were found in the spinal cord. Some neurons in the inner part of the inner nuclear layer of the retina and some retinal ganglion cells were labeled moderately. The pattern of distribution of mGluR2 messenger RNA revealed in the present study indicates specific roles of mGluR2 in the glutamatergic system in the brain.

Animals↗