Search PubMed⌕ Search

Biomedical subjects

M Tohyama

Publications and source records attributed to M Tohyama.

At least 271 records · Page 15Linked to original sources
PubMed1991

Coexistence of acetylcholine and calcitonin gene-related peptide in the vestibular efferent neurons in the rat.

An immunocytochemical study combined with the retrograde tracer technique was performed in the rat to assess the vestibular efferent system. All 3 neuron groups which give rise to axons terminating on the vestibular end-organs were cholinergic, i.e., a group dorsolateral to the genu of the facial nerve (DL), a group dorsomedial to this genu (M), and scattered cells in the parvocellular reticular nucleus (PCRt). In addition, we further demonstrated that about 55% of the cholinergic cells in DL had calcitonin gene-related peptide.

Acetylcholine↗
PubMed1991

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

The expression of mRNA of the beta subunit of the glycine receptor was investigated in the rat by in situ hybridization histochemistry using an oligonucleotide probe specific to the sequence of the beta subunit. Neurons expressing beta subunit mRNA were widely and abundantly distributed in the rat brain from the olfactory bulb to the spinal cord. The pattern of distribution of cells containing beta subunit mRNA in the lower brainstem was very similar to that of cells containing alpha 1 subunit mRNA. In addition, beta subunit mRNA was strongly expressed by the neurons of the cerebral cortex, hippocampal formation and diencephalon as well as by the Purkinje cells where alpha 1 subunit mRNA expression is rare. These findings indicated that the glycine receptor is heterogeneous. The sites where strong labeling was noted were as follows. In the forebrain and diencephalon, strongly labeled neurons were abundant in the olfactory region, hippocampal formation, cerebral cortex, and thalamus. In the hippocampal formation, neurons in the subiculum, pyramidal cells in Ammon's horn, and neurons in the polymorphic layer of the dentate gyrus were strongly labeled. In the thalamus, the anterodorsal, reticular, parafascicular, and the subthalamic nuclei were strongly labeled. In the brainstem, the red nucleus, almost all of the motor neurons in the cranial motor nuclei innervating striated muscles, the trigeminal mesencephalic nucleus, the ventral tegmental nucleus of Gudden, and the pontine nucleus were strongly labeled. In the cerebellum, Purkinje cells in the Purkinje cell layer and all of the cerebellar nuclei were strongly labeled.

Animals↗
PubMed1991

Postnatal ontogeny of cells expressing prepro-neurotensin/neuromedin N mRNA in the rat forebrain and midbrain: a hybridization histochemical study involving isotope-labeled and enzyme-labeled probes.

The postnatal ontogeny of cells expressing prepro-neurotensin/neuromedin N messenger RNA (prepro-NT/NN mRNA) in the rat forebrain and midbrain was investigated by in situ hybridization histochemistry. According to the pattern of expression during development, the cells which express prepro-NT/NN mRNA can be roughly divided into 2 groups. In type I cells, prepro-NT/NN mRNA expression reaches a maximum in terms of content during the postnatal period. After this early peak, cells of this type express the same or less prepro-NT/NN mRNA, reaching a plateau at an adult level that still contains a high level of expression. In type II cells, prepro-NT/NN mRNA appears during the postnatal period, and the expression decreases dramatically after the first postnatal week, being almost undetectable by a few weeks after birth. Type I cells were observed in the following areas: the piriform cortex, field CA1 of Ammon's horn, subiculum, vertical, and horizontal limbs of the diagonal band of Broca, intermediate part of the lateral septal nucleus, bed nucleus of the stria terminalis, medial preoptic area, lateral hypothalamus, caudal part of the caudate putamen, medial, cortical, and central amygdaloid nuclei, ventral tegmental area, deep mesencephalic nucleus, cuneiform nucleus, dorsal raphe nucleus, laterodorsal tegmental nucleus, parabrachial nucleus, and oral part of the pontine reticular nucleus. Cells of type II were observed in the following areas: the mitral cell layer of the olfactory bulb, rostral part of the caudate putamen, (anterior) cingulate cortex, and retrosplenial cortex (posterior cingulate cortex).

Aging↗
PubMed1991

Ultrastructure and retinal innervation of deafferentation-induced enkephalin-immunoreactive elements in the superficial layers of the rat superior colliculus.

Leu-enkephalin-like immunoreactive (ENK-I) elements appearing in the superficial layers of the rat superior colliculus (SC) after eye-enucleation were examined by means of immunoelectronmicroscopy. ENK-I somata were of a single type and formed symmetric and asymmetric synapses with non-immunoreactive axon terminals. Some degenerating retinal terminals made synaptic contacts only with small ENK-I dendrites, suggesting that deafferentation-induced ENK-I neurons in the rat SC receive retinal input onto the distal portions of their dendrites.

Afferent Pathways↗
PubMed1991

Enkephalinergic sympathetic and parasympathetic innervation of the rat submandibular and sublingual glands.

Enkephalinergic innervation of the rat salivary glands was investigated by immunocytochemical techniques. Based upon immunostaining for enkephalin (ENK) and tyrosine hydroxylase (TH), 4 types of neurons could be distinguished in the submandibular ganglion: cells containing both ENK and TH (9% of all ganglion cells), cells containing only ENK (17%), cells containing only TH (4%) and cells lacking both ENK and TH (70%). Almost all of the ganglion neurons were also positive for AChE and so were most of the TH-positive cells. The ENK-positive fibers outnumbered the TH-positive fibers. Although TH-positive fibers displayed concurrent ENK immunoreactivity, fibers in the blood vessel walls were only immunoreactive for TH. Excision of the superior cervical ganglion resulted in a decrease of ENK fibers and the disappearance of most of the TH fibers from the submandibular gland. Most of the remaining ENK-positive fibers were immunonegative for TH, while the remaining TH-positive fibers were also positive for ENK. The salivary gland of the postnatal 8-week-old rats had a considerable number of ENK-positive neurons and fibers in the submandibular ganglion and acini.

Acetylcholinesterase↗
PubMed1991

Transient expression of neurotensin mRNA in the mitral cells of rat olfactory bulb during development.

The transient expression of neurotensin mRNA in the mitral cells of the rat olfactory bulb was demonstrated during the perinatal period using non-radioactive in situ hybridization in which an alkaline phosphatase labelled oligodeoxynucleotide probe was used. The relative cellular content of neurotensin mRNA signal was measured by use of a microdensitometer. Neurotensin mRNA positive cells were observed in the primordium of mitral cells on embryonic day 14 and their mRNA content increased gradually up to the day of birth. During the first postnatal week, the strength of their neurotensin mRNA signal decreased dramatically, and continued to decrease until in the adult olfactory bulb neurotensin mRNA was no longer detectable. This decrease of the neurotensin mRNA content coincided with a parallel decrease of neurotensin immunoreactivity observed in the lateral olfactory tract.

Animals↗
PubMed1991

Different postnatal development profiles of neurons containing distinct GABAA receptor beta subunit mRNAs (beta 1, beta 2, and beta 3) in the rat forebrain.

The expression of three beta subunit (beta 1, beta 2, and beta 3) mRNAs for gamma-aminobutyric acidA receptor in the postnatal rat forebrain was examined by in situ hybridization histochemistry with probes synthesized for the respective subunit mRNAs. The developmental expression of these subunit mRNAs conformed to one of three patterns. Pattern I was high expression of the mRNA at birth and a constant or increasing expression thereafter. In contrast, pattern II was no or very low expression of the mRNA at birth, with expression quickly increasing to reach the adult level in the early postnatal period. Pattern III was the transient expression of the subunit mRNA or else a marked decrease of its expression after a peak in the early postnatal period. On the basis of this classification, the expression of beta 3 subunit mRNA followed pattern I in most regions of the forebrain, such as the isocortex, the olfactory bulb and some of its related areas, the hippocampal formation, the amygdala, the septum, the bed nucleus of the stria terminalis, the caudate-putamen, the nucleus accumbens, the globus pallidus, the ventral pallidum, and the hypothalamus. In some areas, such as the magnocellular preoptic nucleus, the thalamus, and the subthalamic nucleus, pattern III was seen for this subunit. However, none of the regions of the brain showed pattern II expression of beta 3 subunit mRNA. In contrast, the expression of beta 1 and beta 2 subunit mRNAs followed pattern II in most regions of the forebrain. These included the expression of beta 1 subunit mRNA in the isocortex, the olfactory bulb, the hippocampal formation, the amygdala, the septum, the bed nucleus of the stria terminalis, the thalamus, and the hypothalamus, and the expression of beta 2 subunit mRNA in the isocortex, the olfactory bulb and some of its related areas, the amygdala, the nucleus of the diagonal band, the caudate-putamen, the thalamus, and the hypothalamus. Pattern I was not found for beta 1 subunit mRNA, although it was seen in some areas for beta 2 subunit mRNA, such as the ventral pallidum, the globus pallidus, and the magnocellular preoptic nucleus. On the other hand, pattern III was followed by beta 1 subunit mRNA in the anterior olfactory nucleus, the olfactory tubercle, and the piriform cortex, and the same pattern for the beta 2 subunit was also found in the olfactory tubercle, the hippocampal formation, the septum, the bed nucleus of the stria terminalis, and the nucleus accumbens.(ABSTRACT TRUNCATED AT 400 WORDS)

Amygdala↗
PubMed1991

Specific cholinergic destruction in the basal magnocellular nucleus and impaired passive avoidance behavior of rodents.

A nerve growth factor (NGF)-diphtheria toxin conjugate (NGDT) was found to selectively abolish or depress the activity of NGF receptor-bearing cholinergic neurons of the basal magnocellular nucleus (BMN). Bilateral cortical injections of NGDT impaired the retention of passive avoidance behavior in mice. A memory deficit was also revealed when cortical injections of NGDT were administered after the acquisition of a passive avoidance response. Thus, retrograde destruction of BMN cholinergic neurons by the cortical injection of NGDT interfered with both learning and memory processes. The animal model outlined here should be useful in analyzing the pathogenesis of Alzheimer's disease and the functions of the cholinergic system in the BMN.

Animals↗
PubMed1991

Retinal fibers make synaptic contact with neuropeptide Y and enkephalin immunoreactive neurons in the intergeniculate leaflet of the rat.

Direct synapses between retinal fibers and neuropeptide Y (NPY) and/or enkephalin-immunoreactive (ENK-I) neurons were investigated in the intergeniculate leaflet (IGL) of the rat, using combined immunohistochemical and degeneration techniques. Degenerating retinal fibers terminated on dendrites of NPY-I and/or ENK-I neurons. NPY-I fibers in the IGL formed axo-dendritic synapses on non-immunoreactive dendrites. Most of them were asymmetrical synapses. ENK-I axon terminals contacted non-immunoreactive dendrites with symmetrical synapse.

Animals↗
PubMed1991

Different postnatal ontogenic profiles of neurons containing beta (beta 1, beta 2 and beta 3) subunit mRNAs of GABAA receptor in the rat thalamus.

The postnatal ontogeny of neurons containing different GABAA receptor beta (beta 1, beta 2 and beta 3) subunit mRNAs were examined in the rat thalamus using in situ hybridization histochemistry. Neurons containing beta 1 or beta 2 subunit mRNA developed remarkably postnatally, while most neurons were already strongly labeled with beta 3 probe at birth. However, beta 3 subunit mRNA decreased rapidly after birth, few cells being labeled with this probe at day 35 and thereafter.

Aging↗
PubMed1991

The transient appearance of proneurotensin mRNA in the rat hypoglossal nucleus during development.

Using a sensitive non-radioactive in situ hybridization technique utilizing alkaline phosphatase labelled oligodeoxynucleotide neurotensin probe we have observed the transient expression of neurotensin mRNA in the rat hypoglossal nucleus. Neurotensin mRNA containing cells were first observed on embryonic day 14 in the primodium of the hypoglossal nucleus. The intensity of the mRNA signal increased during the perinatal period until a maximum signal was observed at birth. After this time, the intensity of the neurotensin mRNA signal decreased dramatically during the first postnatal week. Subsequently the mRNA signal decreased gradually during maturation until only a very weak signal was detected in the adult. The visualization of neurotensin mRNA containing cells in the hypoglossal nucleus has not previously been reported. The transient expression of NT mRNA containing cells prior to birth may suggest that neurotensin has a role in the development of this nucleus.

Aging↗
PubMed1991

Localization and ontogeny of cells expressing preprodynorphin mRNA in the rat cerebral cortex.

The regional distribution of preprodynorphin (PPD) mRNA-containing cells (PPD cells) in the rat cerebral cortex was investigated by in situ hybridization histochemistry using a synthetic oligonucleotide probe. In the isocortex, PPD cells were small or medium-sized and were mainly located in layer V. While they were less numerous in the allocortex than in the isocortex. Only a few labeled cells were seen in the piriform and entorhinal cortices. In the hippocampal formation, labeled cells were observed in the granular layer of the dentate gyrus. An ontogenetic study revealed that PPD mRNA-containing cells appeared on postnatal day 7 in the isocortex and the allocortex and on day 14 in the dentate gyrus. Thereafter, they increased in number and signal intensity to reach a plateau on postnatal day 14 in both the isocortex and the allocortex and on day 35 in the dentate gyrus. The time-course of development of PPD mRNA-containing neurons in the cerebral cortex suggested that PPD-derived peptide has a neuromodulator and/or neurotransmitter role in these regions of the brain.

Animals↗
PubMed1991

Region-specific expression of the mRNAs encoding beta subunits (beta 1, beta 2, and beta 3) of GABAA receptor in the rat brain.

The expression of mRNAs encoding different beta subunits (beta 1, beta 2, and beta 3) of the gamma-aminobutyric acid A (GABAA) receptor in the rat brain was investigated by in situ hybridization histochemistry. Transcripts of each subunit showed region-specific localization. Some areas contained all three beta subunit mRNAs, while other areas showed marked differences in the location and level of expression of each subunit mRNA. The regions with strong to very strong labeling by the beta 3 probe were as follows: the olfactory bulb, the cortex, the caudate-putamen, the accumbens nucleus, the hypothalamus, the amygdala, the hippocampal formation, and some areas of the brainstem and spinal cord. Weak to moderate labeling was detected in the thalamus, superior and inferior colliculus, and many areas of the brainstem. The regions with strong to very strong labeling by the beta 2 probe were as follows: the olfactory bulb, the ventral pallidum, the globus pallidus, the nucleus of the diagonal band, the preoptic magnocellular nucleus, the thalamus, the subthalamic nucleus, the substantia nigra, and the cerebellum. Weak to moderate labeling was detected in the regions that showed strong expression of beta 3 subunit mRNA. Expression of beta 1 subunit mRNA was only weak to moderate compared to that of the beta 2 and beta 3 subunit mRNAs. The regions with moderate labeling by the beta 1 probe were the following: the cortex, the claustrum, the bed nucleus of the stria terminale, some nuclei of thalamus and amygdala, the hypothalamus, the hippocampal formation, the subiculum, the cerebellum, and several areas of the brainstem and spinal cord. Thus, our findings showed that the beta subunit mRNAs of the GABAA receptor were differentially expressed in the rat brain, perhaps indicating the existence of different subtypes of the GABAA receptor in different brain regions.

Animals↗
PubMed1991

Neurotensin and neuromedin N elevate the cytosolic calcium concentration via transiently appearing neurotensin binding sites in cultured rat cortex cells.

Through assessment of the changes in the intracellular free-calcium concentration ([Ca2+]i), which was measured using the calcium sensitive dye, fura-2, the character of the neurotensin (NT) binding sites which appeared transiently during the early ontogenetic stage in the rat cerebral cortex was analyzed in primary cultures of cerebral cortex cells from neonatal rats. NT (1-1000 nM) elevated [Ca2+]i of the cells even when extracellular calcium was chelated with 1 mM ethylene glycol-bis(beta-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA). These findings suggest that the transiently appearing NT-binding sites in the cortex are receptors for NT and that some of the NT-induced increase in [Ca2+]i is due to mobilization from the intracellular calcium store. Further application of NT after 10 min washing caused an increase in [Ca2+]i again. This is in contrast to the findings for cortical slices from adult rats and mRNA-injected oocytes; desensitization due to NT was of long duration and further application of NT failed to activate the neurons which had responded the first time to NT. These facts suggest that the character of the NT-binding sites in the cerebral cortex differs between neonatal and adult rats. In addition, we showed that neuromedin N had a similar property to NT as to mobilization of [Ca2+]i and acted only on NT-responsive cells, suggesting the interaction between NT and neuromedin N at the postsynaptic level via the same receptor.

Amino Acid Sequence↗
PubMed1991

Fine structure of synapses and retinal innervation of substance P and adenosin deaminase containing neurons in the superior colliculus of the rat.

The fine structure of substance P (SP) and adenosine deaminase (ADA) immunoreactive structures in synaptic contacts localized to the superficial layers of the superior colliculus of the rat was investigated by means of immunoelectron microscopy. We also examined the possibility of retinal innervation of SP- and ADA- containing neurons by immunohistochemistry after degeneration of retinal terminals caused by enucleation. SP-like immunoreactive presynaptic terminals of the stratum griseum superficiale (SGS) formed both asymmetric and symmetric synaptic contacts. Presynaptic dendritelike structures were also observed. SP immunoreactive postsynaptic elements made contacts with terminals showing diverse features. ADA-like immunoreactive structures were seen only as postsynaptic elements to different kinds of nonimmunoreactive terminals and were mostly localized in the ventral third of the SGS and the dorsalmost stratum opticum (SO). After enucleation, degenerating retinal terminals were found to form synaptic contacts with SP and ADA immunoreactive structures. The highest number of such degenerating terminals on ADA immunoreactive structures was observed 2 days after retinal denervation, very few being seen after 5 days. These degenerating terminals were restricted to the ventral SGS and dorsal SO. SP immunoreactive structures postsynaptic to degenerating retinal terminals were most numerous 5 days after enucleation and mainly localized in the dorsal SGS. Occasionally, SP immunoreactive dendritelike processes forming synapses with degenerating retinal terminals were simultaneously presynaptic to other nonimmunoreactive profiles, defining, therefore, serial synapses. The present results suggest that SP-I and ADA-I collicular neurons may be part of distinct channels carrying visual information to the lateral posterior and lateral geniculate nuclei of the thalamus, respectively.

Adenosine Deaminase↗
PubMed1991

Changes in expression of peptides in rat facial motoneurons after facial nerve crushing and resection.

In situ hybridization histochemistry was used to study changes in mRNAs coding neuropeptides such as alpha-calcitonin gene-related peptide (CGRP), beta-CGRP, cholecystokinin (CCK) and galanin, in rat facial motoneurons following axotomy of the facial nerve. In control rats, 38%, 55% and 7% of the facial motoneurons expressed alpha-CGRP, beta-CGRP and CCK mRNAs, respectively. No galanin mRNA-containing motoneurons were observed in these animals. The levels of mRNA for alpha-CGRP, CCK and galanin were increased while the beta-CGRP mRNA level was decreased after axotomy. The levels of mRNAs for these peptides returned to the control values by 2-4 weeks after nerve crush, whereas nerve resection had more prolonged effects. Within 3-4 weeks after injury, nerve resection had greater effects on beta-CGRP, CCK and galanin mRNAs than did nerve crush. Thus, there appear to be differences in the regulation of mRNA expression of these peptides in axotomized motoneurons.

Animals↗
PubMed1991

Distribution of GABAA-receptor alpha 1 subunit gene expression in the rat forebrain.

The localization of neurons containing mRNA of the alpha 1 subunit of the gamma-aminobutyric acid-A (GABAA) receptor was examined in the rat forebrain by in situ hybridization histochemistry using an oligonucleotide probe for the alpha 1 subunit. Moderately to strongly labeled neurons were numerous in the mitral cell layer of the olfactory bulb, the anterior olfactory nucleus, the diagonal band of Broca, the globus pallidus, the tenia tecta, the hippocampal formation, the thalamic and subthalamic nuclei, the zona incerta, and the amygdaloid complex. A few positive neurons were found in the caudate-putamen, the lateral and medial septal areas, the nucleus accumbens, the bed nucleus of the stria terminalis, the ventral pallidum, and the hypothalamus. The distribution of neurons containing alpha 1 subunit mRNA in the forebrain was very similar to that of neurons expressing beta 2 subunit mRNA, suggesting that these two subunits frequently coexist in the same neurons in the forebrain.

Animals↗