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Biomedical subjects

M Tohyama

Publications and source records attributed to M Tohyama.

At least 289 records · Page 16Linked to original sources
PubMed1991

Effects of nerve crush and transection on mRNA levels for nerve growth factor receptor in the rat facial motoneurons.

We found that the level of nerve growth factor receptor (NGF-R) mRNA in facial motoneurons was increased after both facial nerve crushing and transection by means of in situ hybridization histochemistry. The increased level of NGF-R mRNA was maintained for at least 8 weeks after facial nerve transection, while facial nerve crushing caused only a transient increase. Thus, expression of NGF-R mRNA paralleled the axonal regeneration process. In addition, the increase of NGF-R mRNA with crushing was more pronounced than with transection from the 3rd to the 14th day after the insult.

Animals↗
PubMed1991

Striatal calcitonin gene-related peptide-like immunoreactive afferents from the regions ventral and medial to the medial geniculate nucleus of rats.

The sources of fibers with immunoreactivity to calcitonin gene-related peptide in the caudal portion of the caudate-putamen were investigated in animals treated by a knife cut, a tracer injection, or an electrolytic lesion of regions ventral and medial to the medial geniculate nucleus. Hemitransection of the brain just caudal to the caudate-putamen decreased ipsilaterally calcitonin gene-related peptide-like immunoreactivity in the caudal portion of the caudate-putamen, suggesting that calcitonin gene-related peptide-like immunoreactive fibers in the caudate-putamen originated from neurons in the area caudal to the caudate-putamen. Some calcitonin gene-related peptide-like immunoreactive neurons in the regions ventral and medial to the medial geniculate nucleus, including the peripeduncular, posterior intralaminar and suprageniculate nuclei, were labeled ipsilaterally with a retrograde tracer after an injection into the caudal portion of the caudate-putamen. In addition, an electrolytic lesion of calcitonin gene-related peptide-like immunoreactive neurons in the regions ventral and medial to the medial geniculate nucleus decreased the number of calcitonin gene-related peptide-like immunoreactive fibers in the ipsilateral caudal portion of the caudate-putamen. These results suggest that some cells containing calcitonin gene-related peptide in several posterior thalamic nuclei project to the caudal caudate-putamen.

Animals↗
PubMed1991

Effects of eye-enucleation on substance P-immunoreactive fibers of some retinorecipient nuclei of the rat in relation to their origin from the superior colliculus.

We have previously shown that retinal deafferentation causes a decrease in immunoreactive dendrites of substance P-positive neurons of the superficial superior colliculus of the rat. Since some retinorecipient thalamic and pretectal nuclei are putative targets for substance P-containing cells of the superior colliculus, the present study attempted to ascertain whether substance P-immunoreactive fibers in these nuclei are also affected by retinal denervation. We found that unilateral eye removal produced a progressive increase in fibrous substance P immunoreactivity in the nucleus of the optic tract, lateral posterior nucleus, and lateral geniculate nucleus of the side contralateral to the enucleation. On the other hand, unilateral lesions to the superficial layers of the superior colliculus produced a dramatic reduction in substance P immunoreactivity in the ipsilateral nucleus of the optic tract, lateral posterior nucleus, and dorsal and ventral lateral geniculate nuclei. In bilaterally enucleated animals, unilateral lesion to the superior colliculus produced, as expected, loss of immunoreactive fibers only in the lateral posterior nucleus and the retinorecipient nuclei ipsilateral to the lesion. These results suggest that transneuronal changes in the distribution of substance P in collicular neurons observed after enucleation could be reflected in their projections to the other primary visual centers and to the lateral posterior nucleus.

Animals↗
PubMed1991

Localization of glycine receptor alpha 1 subunit mRNA-containing neurons in the rat brain: an analysis using in situ hybridization histochemistry.

The localization of glycine receptors in the rat brain was examined by means of in situ hybridization histochemistry using an oligonucleotide probe to the sequence of the alpha 1 subunit. Strongly- or moderately-labeled neurons were found in the cranial nuclei, sensory nuclei such as the spinal trigeminal nucleus, principal trigeminal nucleus, gracile and cuneate nuclei, dorsal and ventral cochlear nuclei, superior olivary nucleus, medial and lateral trapezoid nuclei, lateral lemniscus and vestibular nuclei, red nucleus, parabrachial area, cerebellar nuclei, dorsal tegmental nucleus, reticular formation and parafascicular nucleus. This study thus demonstrated the localization of neurons which are regulated by glycine via strychnine-sensitive glycine receptors in the rat brain.

Animals↗
PubMed1991

Somato-, branchio- and viscero-motor neurons contain glutaminase-like immunoreactivity.

Immunocytochemistry combined with a fluorescent dye tracer method revealed that somatic, branchial and visceral motoneurons in the brainstem and spinal cord of the rat contain phosphate-activated glutaminase (PAG). An excitatory neurotransmitter glutamate is synthesized mainly through this enzyme. Among these motoneurons, neurons in the dorsal motor nucleus of the vagus nerve (dmnX), autonomic preganglionic neurons in the spinal cord and urethral sphincter motoneurons (DL) were most intensely immunostained. PAG is co-expressed with choline acetyltransferase, calcitonin gene-related peptide or galanin in these neurons. These findings, together with the findings that motor endplates in urethral sphincter muscle contain PAG and PAG-like immunostaining in dmnX motoneurons was decreased after axotomy, suggest that glutamate is a co-transmitter of acetylcholine in motoneurons. Brainstem motoneurons were moderately stained, while somatic motoneurons in the spinal cord other than DL, showed very weak staining for PAG. However, they showed intense PAG-like immunoreactivity at their premature stage, suggesting that glutamate has some effects on the maturation of these neurons. A variety of functional roles of glutamate in motoneurons is discussed.

Animals↗
PubMed1991

A sex-specific cytochrome P-450(F-1) colocalized with various neuropeptides in the paraventricular and supraoptic nuclei of female rats.

Numerous cells containing P-450(F-1) were detected in the magnocellular and parvocellular neurons of the paraventricular nucleus of the hypothalamus. Electron microscopic analysis of immunoreactive neurons has shown that P-450(F-1) immunoreactivity is present on the Golgi apparatus and rough endoplasmic reticulum. In the paraventricular nucleus, the P-450(F-1)-positive magnocellular neurons frequently contained oxytocin and some of them also contained CRF. Vasopressin was colocalized with P-450(F-1), but these neurons did not express CRF. In the supraoptic nucleus, P-450(F-1) was colocalized with oxytocin or CRF in single neurons, but not with vasopressin. No cells exhibiting the colocalization of both P-450(F-1) and somatostatin were observed in these nuclei. The results of the present study concerning colocalization of P-450 and peptides suggest that P-450(F-1) is involved in the hypothalamo-hypophyseal neuroendocrine function in the female rat.

Animals↗
PubMed1991

Catecholamine and acetylcholine in the rat cerebral cortex with special reference to pathogenetic mechanisms of Alzheimer's disease.

A direct synapse between catecholamine fibers and neuropeptide Y-containing neurons is demonstrated in rat cerebral cortex using an immunohistochemical double-staining method under the electron microscope. A new method to produce a selective reduction in cholinergic neurons in the basal forebrain without damage to the non-cholinergic neurons, passing fibers or other cholinergic systems, is described. This animal model seems to be very useful to analyze the pathogenesis of Alzheimer's disease and to examine the function of cholinergic neurons of the basal forebrain.

Acetylcholine↗
PubMed1990

Ontological study of calbindin-D28k-like and parvalbumin-like immunoreactivities in rat spinal cord and dorsal root ganglia.

The calcium ion plays an important role in some critical developmental events in the nervous system, such as neurulation and neurite elongation. Therefore, as the intracellular calcium-binding proteins calbindin-D28k (CaB) and parvalbumin (PV) may be expressed in these developmental events. Accordingly, the ontological expression of CaB and PV was examined immunocytochemically in the spinal cord and dorsal root ganglia (DRG) of the rat, in order to evaluate the relationship between CaB and PV expression, and other important developmental events. During the ontogenesis of the spinal cord, the CaB-like immunoreactivity was mainly observed in the cell somata. The immunoreactive cells in the ventral horn of the cervical and thoracic, lumbar, and sacral segments first appeared at embryonic day (E)-12, E-13, and E-14, respectively. However, these cells were not detected in the intermediate gray matter of the same segments at E-14, E-15, and E-16, respectively, and in the dorsal horn at E-14-E-15, E-16, and E-17, respectively. The peak of immunoreactive cells, both as to number and intensity, occurred in the perinatal period. However, from postnatal day (P)-14 on, the number and intensity of the positive cells decreased, the adult levels being reached at P-35. The PV-like immunoreactivity was mainly detected in the fibers and punctata during the ontogenesis of the spinal cord. The immunoreactive fibers first appeared on the surface of the dorsal horn in the cervical and thoracic segments at E-14, then entered the dorsal horn at E-15, and reached the intermediate gray matter and ventral horn at E-16. The first appearance of these fibers in the same areas of the lumbar and sacral segments occurred 1 day later than in the cervical and thoracic segments. During the perinatal period, the maximum content of PV-like immunoreactive fibers, together with many punctata, was seen in the gray matter. However, between P-14 and P-17, most of them lost immunoreactivity rapidly, with the exception of the medial region of the intermediate gray matter, where the PV-immunoreactive punctata remained up to the adult stage. In DRG neurons, both CaB and PV was expressed, but in different neurons. Neurons labeled with anti-CaB and anti-PV sera were first detected at E-16 and E-14, respectively. These neurons were large or medium-sized in the prenatal period.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Localization of two calcium binding proteins, calbindin (28 kD) and parvalbumin (12 kD), in the vertebrate retina.

We used immunocytochemistry to locate two calcium binding proteins, calbindin (CaB) and parvalbumin (PV), in the retina of goldfish, frog, chick, rat, guinea pig, dog, and man. The location of CaB depended on the type of dominant photoreceptor cells in birds and mammals. In cone-dominant retinas such as those of the chick, CaB-like immunoreactivity was found in the cones, cone bipolars, and ganglion cells. Amacrine cells 5-12 microns across were also labeled. In rod-dominant retinas, such as those of the rat, guinea pig, and dog, horizontal cells, small amacrine cells (about 6 microns across), and cells in the ganglion cell layer were labeled. In the human retina, which has both cones and rods in abundance, cones, cone bipolars, ganglion cells, horizontal cells, and small and large amacrine cells were labeled. In the frog and goldfish, the level of CaB-like immunoreactivity was low. In the frog, a few cones, amacrine cells, and cells in the ganglion cell layer were labeled. No immunoreactive structures were seen in the goldfish retina. PV-like immunoreactivity was found in chicks, rats, and dogs. No such immunoreactive structures were seen in the other species. In the chick, only amacrine cells were labeled. In the rat, amacrine cells and several displaced amacrine cells were labeled. In the dog, in addition to amacrine cells and displaced amacrine cells, horizontal cells were strongly labeled. Thus, PV-like immunoreactivity was found in those elements relating to the modulation of the main pathway of the visual transmission system.

Animals↗
PubMed1990

The differential expression patterns of the mRNAs encoding beta subunits (beta 1, beta 2 and beta 3) of GABAA receptor in the olfactory bulb and its related areas in the rat brain.

The expression of mRNAs encoding different beta subunits (beta 1, beta 2 and beta 3) of GABAA receptor in the rat olfactory bulb and some of its related areas was investigated by in situ hybridization histochemistry. The beta 3 subunit mRNA was expressed in most of the cells in these regions such as periglomerular cells, tufted cells, mitral cells and granule cells in olfactory bulb, and the cells in anterior olfactory nucleus, piriform cortex and olfactory tubercle. However, only several kinds of these cells contained beta 2 subunit mRNA such as tufted cells and mitral cells of olfactory bulb, and the cells in anterior olfactory nucleus and piriform cortex. The beta 1 subunit mRNA was only detected in the mitral cells of olfactory bulb.

Animals↗
PubMed1990

Calbindin D28k-containing splanchnic and cutaneous dorsal root ganglion neurons of the rat.

Calbindin D28k (CaBP)-containing splanchnic and cutaneous sensory neurons in the rat dorsal root ganglia (DRGs) were investigated immunocytochemically in combination with a fluorescent dye tracer (Fluoro gold). About 15% of the DRG neurons at Th9-10 levels showed CaBP-like immunoreactivity. Eighty-four % of the splanchnic sensory neurons were immunoreactive to CaBP, while only 3% of the cutaneous sensory neurons were. The diameters of the splanchnic and cutaneous sensory neurons containing CaBP were 23.4 +/- 6.3 microns and 38.4 +/- 8.8 microns, respectively. Splanchnic sensory neurons containing CaBP were sensitive to capsaicin while cutaneous ones were not. These findings suggest that CaBP-containing splanchnic and cutaneous sensory neurons constitute different subgroups among the DRG neurons at the lower thoracic level.

Animals↗
PubMed1990

Substance P and enkephalins in the superficial layers of the rat superior colliculus: differential plastic effects of retinal deafferentation.

In this work we studied the effects of unilateral eye enucleation on the contents and distribution of leu-enkephalin-, met-enkephalin-arg6-gly7-leu8-, and substance-P-like immunoreactivities (L-ENK-I, ENK-8-I, and SP-I, respectively) in the superficial layers of the rat superior colliculus (SC) by means of the unlabelled antibody peroxidase-antiperoxidase method. In the normal rat only a few L-ENK-I neurons appear dispersed in the stratum griseum superficiale. No immunostained somata appear in the stratum opticum. The most striking effect of unilateral enucleation was the dramatic appearance of a laminarly distributed population of L-ENK-I and/or ENK-8-I neurons in the dorsal stratum opticum of the SC contralateral to the enucleated side. This population of immunoreactive cells was observed with all the survival times examined in the present study (3, 7, 15, and 30 days) and was always accompanied by an increase in the immunostaining of L-ENK-I and/or ENK-8-I fibers in the contralateral stratum griseum superficiale. Enucleation also produced a decrease in the immunostaining of SP-I dendrites that only became obvious 15 days after enucleation. However, the number of SP-I somata or terminal-like immunoreactive structures showed no detectable changes. These results show that retinal deafferentation of the superficial layers of the rat SC has different effects on some immunohistochemically distinguishable neuronal subgroups in the SC, suggesting different functional or trophic relationships of the retinal input to these groups of neurons.

Afferent Pathways↗
PubMed1990

Fine structure of noradrenergic terminals and their synapses in the rat spinal dorsal horn: an immunohistochemical study.

Noradrenergic fibers in the spinal dorsal horn originate from neurons in the A5-7 cell groups, and may participate in the modulation of pain. Here we studied the fine structure of noradrenergic terminals in the rat by immunohistochemistry using antiserum against dopamine-beta-hydroxylase (DBH). We also investigated the relationship between such terminals and primary afferent terminals. DBH-like immunoreactive terminals were found in lamina I and the outer layer of lamina II of the dorsal horn and they contained many clear round vesicles and some large granular vesicles. More than half of these terminals made synaptic contact with other neuronal elements with membrane specialization. Most of the postsynaptic structures of these terminals were small dendrites (69%); 28% were spines, and no synaptic contact was made with primary afferent terminals. These findings suggest that noradrenaline acts on the spinal dorsal horn neurons postsynaptically mainly via a direct synaptic mechanism.

Animals↗
PubMed1990

Histamine acts directly on calcitonin gene-related peptide- and substance P-containing trigeminal ganglion neurons as assessed by calcium influx and immunocytochemistry.

Primary cultures of rat trigeminal ganglion cells were exposed to histamine, and the intracellular free-calcium concentration, [Ca2+]i, was measured by the calcium-sensitive dye fura-2. Histamine increased the [Ca2+]i of the neurons. Pretreatment of the cells with histamine H1-receptor blocker, or removal of extracellular calcium, abolished the response, however, the response was not altered by pretreatment with H2-blocker. Immunocytochemical analysis showed that these cultured cells that responded to histamine identically showed substance P- or calcitonin gene-related peptide-like immunoreactivity.

Animals↗
PubMed1990

Presence of VIP fibers of sensory origin in the rat trachea.

The presence of vasoactive intestinal peptide (VIP) immunoreactive nerve fibers (LI) in the respiratory tract of mammals is well documented. These fibers are known to originate from parasympathetic postganglionic neurons and to be associated with blood vessels, submucosal glands, and with smooth muscle. We found that, in addition to this, the epithelial layer of the rat trachea also contains VIP-LI fibers. Vagotomy or ligation of the cervical portion of the vagus nerve resulted respectively in a decrease of VIP-LI fibers within the epithelium or in the accumulation of VIP in axons proximal to the site of transection or ligation, whereas no changes were seen in other parts of the trachea. On the other hand, capsaicin pretreatment also caused similar changes to the surgical procedures. These findings indicate that VIP-LI fibers in the tracheal epithelium of the rat are supplied by the sensory ganglia of the vagus nerve.

Animals↗
PubMed1990

Different ontogenetic profiles of cells expressing prepro-neurotensin/neuromedin N mRNA in the rat posterior cingulate cortex and the hippocampal formation.

The ontogeny of the expression of prepro-neurotensin/neuromedin N messenger RNA (prepro-NT/NN mRNA) in the rat posterior cingulate cortex (retrosplenial cortex) and the hippocampal formation was investigated using in situ hybridization histochemistry. In the primordium of the posterior cingulate cortex and the hippocampal formation, prepro-NT/NN mRNA was first expressed on embryonic day 17, and was found in the subiculum, layers II-III in areas 29a and 29b, and layer VI in the posterior cingulate cortex at birth. Expression was also observed in the CA1 field. In the adult rat, the expression of prepro-NT/NN mRNA was reduced in the posterior cingulate cortex, and only a few positive cells were seen here. However, the CA1 field and the subiculum still contained numerous positive cells.

Animals↗
PubMed1990

Appearance of substance P-like immunoreactive neurons in the rat superior colliculus after neonatal eye enucleation.

The possibility that eye enucleation within one day after birth has an effect on the postnatal development of substance P (SP)-like-immunoreactive (SP-I) structures in the superior colliculus (SC) was investigated in the rat. Results were compared with those in animals enucleated at postnatal day 15. All the animals were allowed to survive until postnatal day 90, after which changes in SP-I neurons and fibers were identified immunohistochemically. In colchicine-treated rats, the most remarkable changes occurred in SP-I neurons following eye enucleation at birth; large numbers of SP-I neurons appeared in the ventral part of the stratum griseum superficiale (SGS), stratum opticum (SO) and stratum griseum intermediale (SGI) of the deafferentated SC. SP-I neurons did not appear in these layers, when deafferentation of the SC was carried out in rats at postnatal day 15. These findings suggest strongly that eye enucleation at birth affects the production of SP of neurons in the ventral part of the SGS, SO and SGI at the deafferentated SC. The appearance of SP-I neurons in the neonatal eye enucleation may be due, at least partially, to reorganization of another neuronal system in the SC.

Animals↗