Biomedical subjects

Y Nojyo

Publications and source records attributed to Y Nojyo.

At least 37 records · Page 2Linked to original sources

PubMed1994

Ultrastructural analysis of tyrosine hydroxylase-, substance P-, and calcitonin gene-related peptide-immunoreactive nerve fibers in the rat iris.

Different patterns of distribution of chemically different nerve fibers in the rat iris were studied by immunoelectron microscopy. The iris was immunostained either singly for tyrosine hydroxylase (TH), or doubly for substance P (SP) and calcitonin gene-related peptide (CGRP), or triply for TH, SP and CGRP. TH-positive fibers were distributed in the stroma near the iris dilator and within the iris sphincter. SP/CGRP-positive fibers were found mainly in the anterior half of the stroma and partly in the stroma close to the sphincter, but were hardly ever seen in the stroma near the dilator or within the sphincter. Fibers neither positive for TH, SP nor CGRP were observed in the stroma near the dilator and within the sphincter.

Animals↗

PubMed1994

[An immunoelectron microscopic study of distribution and density of nerve fibers innervating the rat iris].

We studied the sympathetic, parasympathetic and sensory nerve fibers in the rat iris using electron microscopic immunohistochemical techniques. Antibodies raised against tyrosine hydroxylase (TH), substance P (SP), and calcitonin gene-related peptide (CGRP) were used alone or combined together to characterize the nerve fibers. The ratios of the TH-positive, SP/CGRP-positive and TH/SP/CGRP-negative fibers were 18%, 37%, and 45% in the anterior half of the dilator stroma, 11%, 3%, and 86% in the posterior half of the dilator stroma, 45%, 26%, and 29% in the sphincter stroma, and 23%, 1%, and 76% in the sphincter muscle layer. These results confirm that the sympathetic and parasympathetic fibers doubly innervate both rat iris sphincter and iris dilator muscles, whereas sensory nerve fibers innervate mainly the stroma.

Adrenergic Fibers↗

PubMed1993

Projection of the entorhinal layer II neurons in the rat as revealed by intracellular pressure-injection of neurobiotin.

A component of the perforant path, projection of the entorhinal layer II neurons, was investigated by recovering intracellularly labeled layer II neurons from the medial or intermediate entorhinal cortex in rats. The labeled layer II spiny stellate neurons had axon collaterals in layers I, II, and III of the entorhinal cortex as well as some axon collaterals in the subiculum. The stem axons gave rise to terminal axon branches that covered the entire extent (suprapyramidal blade, crest, and infrapyramidal blade) of the dentate gyrus and the CA2-3 fields in the transverse plane, forming a sheet-like formation. The axon arbor in the hippocampal formation spread up to 2 mm wide in a septotemporal direction. The sheet-like formation of the axon arbors was a narrow layer in the suprapyramidal blade and in the stratum lacunosum-moleculare of the CA2-3 fields. The layer became wider in the crest and infrapyramidal blade of the dentate gyrus. This study shows that the entorhinohippocampal circuit is not a simple circle from single cells level.

Animals↗

PubMed1993

Development of the sympathetic innervation to the cerebral arterial system in neonatal rats as revealed by anterograde labeling with wheatgerm agglutinin-horseradish peroxidase.

In order to clarify the developmental pattern in the sympathetic nerve fibers innervating the cerebral arterial system during the postnatal period in rats, we labeled the postganglionic nerve fibers originating in the superior cervical ganglion (SCG) and directly observed their extension and plexus formation by means of anterograde labeling with wheat germ agglutinin-horseradish peroxidase (WGA-HRP). The WGA-HRP solution was injected into the right SCG 1-7 days after birth. The rats were killed 48 h after trace injection, and the cerebral arteries were reacted with tetramethylbenzidine, then observed as a whole mount preparation. The labeled nerve fibers appeared as a few relatively straight bundles with branching fibers running longitudinally to the long axis of the artery in the ipsilateral right side of the circle of Willis and proximal portion of their main branching arteries at 3 days after birth. The nerve fibers started to form a circular pattern of nerve plexus only on the wall of the circle of Willis as early as 1 week after birth. At the beginning of postnatal week 2, labeled nerve fibers extended the collateral projections into the collateral side of the circle of Willis, and these expanding projections could not be observed at postnatal week 3. We observed a route of the sympathetic nerve fibers advancing into the cerebral arterial system which has not been described in previous studies; bundle of labeled nerve fibers entered into the wall of the middle portion of the basilar artery in half of the animals, in any postnatal period.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1992

Plasticity of the sympathetic nervous system innervating the cerebral arteries in rats.

In order to investigate the neuroplasticity of the peripheral sympathetic nervous system innervating the cerebral blood vessels, we observed and traced the sprouting nerve fibers originating in the contralateral superior cervical ganglion (SCG) into the previously denervated cerebral arteries following unilateral excision of the SCG and/or decentralization of the contralateral SCG in young rats (4 weeks old). These nerve fibers were labeled anterogradely with wheat germ agglutinin-horseradish peroxidase or stained immunohistochemically with anti-tyrosine hydroxylase antibody. Eight weeks after the right SCG excision, reinnervating nerve fibers originating in the contralateral ganglion formed a circular pattern of nerve plexus only on the wall of the main cerebral arteries of the circle of Willis in the ganglionectomized side. However, the decentralization of the contralateral SCG, which was performed simultaneously with a unilateral SCG excision, prevented the nerve sprouting into the denervated regions. Unilateral decentralization of SCG itself failed to affect their distribution pattern or their density of nerve fibers originating in the ganglion. It is concluded that in the young rat the outgrowth of the sympathetic nerve fibers into the denervated cerebral arteries was strongly impeded by the disconnection of ganglion cells from the central nervous system, while the decentralization alone could not affect the innervation pattern of the postganglionic fibers which have been already built-up in the cerebral arterial system.

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PubMed1992

Monoclonal antibodies specific to quail embryo tissues: their epitopes in the developing quail embryo and their application to identification of quail cells in quail-chick chimeras.

Quail-chick chimeras have been used extensively in the field of developmental biology. To detect quail cells more easily and to detect cellular processes of quail cells in quail-chick chimeras, we generated four monoclonal antibodies (MAb) specific to some quail tissues. MAb QCR1 recognizes blood vessels, blood cells, and cartilage cells, MAb QB1 recognizes quail blood vessels and blood cells, and MAb QB2 recognizes quail blood vessels, blood cells, and mesenchymal tissues. These antibodies bound to those tissues in 3-9-day quail embryos and did not bind to any tissues of 3-9-day chick embryos. MAb QSC1 is specific to the ventral half of spinal cord and thymus in 9-day quail embryo. No tissue in 9-day chick embryo reacted with this MAb. This antibody binds transiently to a small number of brain vesicle cells in developing chick embryo as well as in quail embryo. A preliminary application of two of these MAb, QCR1 and QSC1, on quail-chick chimeras of neural tube and somites is reported here.

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PubMed1991

Crossing fiber arrays in the rat hippocampus as demonstrated by three-dimensional reconstruction.

The hippocampus is a neural substrate playing a key role in short-term memory. In order to achieve a better understanding of how the hippocampus functions in "learning and memory," we conducted an intracellular horseradish peroxidase (HRP) study of the CA3 pyramidal neurons and the granule cells of the fascia dentata. The axon of the CA3 pyramidal neurons has two components, the longitudinal association system and the Schaffer collateral system. The latter component is organized in a lamellar fashion and follows the alvear fiber stream. An electron microscopic analysis of myelinated fibers suggested that most myelinated fibers in the hippocampus are organized parallel to the alvear fibers. The mossy fibers of the granule cells, however, do not follow the alvear fiber stream. We propose a new model of the organization of the intrinsic excitatory circuitry of the rat hippocampus in which the distinct lamellar organization of the pyramidal and granule cells creates a crossing neural network.

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PubMed1991

Patterns of reinnervation of denervated cerebral arteries by sympathetic nerve fibers after unilateral ganglionectomy in rats.

In order to clarify the manner in which previously denervated cerebral arteries become reinnervated after unilateral excision of the superior cervical ganglion (SCG), we observed directly the reinnervating sympathetic nerve fibers originating in the contralateral SCG by using anterograde labeling with wheat germ aggulutinin-horseradish peroxidase in rats. The nerve fibers sprouted from the nerve fibers in the contralateral anterior cerebral artery and reinnervated the arterial wall of the anterior cerebral artery of the denervated side as early as one week after ganglionectomy. In addition to this sprouting route, three other reinnervating nerve fiber routes were observed in the circle of Willis of the denervated side two weeks after ganglionectomy: the proximal portion of the internal carotid artery, the route passing between bilateral ethmodial arteries, and the posterior communicating artery. Eight weeks after ganglionectomy, these reinnervating nerve fibers formed a fairly dense plexus in a circular pattern in the circle of Willis. However, the reinnervation could not be observed in the arterial branches derived from the circle of Willis (middle cerebral artery and posterior cerebral artery) even 16 weeks after ganglionectomy. The present results clearly demonstrated the time course, distribution pattern and limitation of the reinnervation from the contralateral SCG following unilateral ganglionectomy. The fact that reinnervation could be observed only in the main cerebral arteries of the circle of Willis, in which the nerve plexus appeared to have a circular pattern, suggests a difference between the qualities of sympathetic innervation controlling the cerebral circulation in these arteries and the other arterial branches related to these differences in reinnervation capacity.

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PubMed1991

[An in vitro rapid evaluation of drug-induced ototoxicity and of reductive effect of calcium on aminoglycoside ototoxicity using organ culture].

The ototoxicity of aminoglycoside and anticancer platinum drug was analysed using an organ culture system. The effect of calcium antagonism on aminoglycoside ototoxicity was investigated by the same system. The inner ears of mice, 16-day embryos, were cultured for 5 days with or without gentamicin (GM) or kanamycin (KM) or streptomycin (SM), or ribostamycin (RSM), including 1, 10, 100, or 1000 micrograms/ml respectively. The 21st gestational day-inner ear was cultured in vitro during 4 days with or without Cisplatin (CDDP) or platinum analog DWA2114R (DWA), including 0.1, 1, or 10 micrograms/ml, respectively. The 16th gestational day-inner ear was cultured in vitro for 5 days with 10 micrograms/ml KM, adding 5 mM Ca2+ or 10 mM Ca2+ to the culture medium. The damages of crista ampullaris and macula utriculi of cultured inner ear were estimated according to the ototoxicity score based on morphological changes by a light microscopic observation of serial sections of the materials. We defined four grades for the damages according to the following criteria; grade 1: damage of apical surface of the hair cells, grade 2: the existence of debris in the endolymph space, grade 3: disappearance of the hair cells, grade 4: degeneration of the supporting cells. Using this system following results were obtained: 1) the effect of aminoglycoside was dose dependent, 2) the order of ototoxicity was following; GM greater than KM greater than SM greater than RSM, 3) the drug concentration of 1000 micrograms/ml is sufficient to study its ototoxic potential in this system, 4) the effect of both CDDP and DWA was obvious at a concentration of 0.1 microgram/ml, 5) DWA showed almost the same ototoxicity as CDDP at the same concentration, 6) Adding 5 mM Ca2+ or 10 mM Ca2+ to the culture medium, the ototoxic damage induced by 10 micrograms/ml of KM was not noticed. A protective effect of Ca2+ against KM ototoxicity was observed in vitro. This organ culture and ototoxicity score system can serve as a useful and adequate model system for evaluating the ototoxicity.

Aminoglycosides↗

PubMed1990

Disposition of the slab-like modules formed by axon branches originating from single CA1 pyramidal neurons in the rat hippocampus.

The hippocampus is thought to be an area where the neuronal circuits for short-term memory or the cognitive map may reside. In order to advance theoretical studies and neuronal model simulations of such circuits, the projection of the CA1 pyramidal neurons in the rat dorsal hippocampus, especially in the subiculum, was studied by means of intracellular and extracellular HRP injection. The CA1 pyramidal neurons project principally to the subiculum where each forms a slab-like axonal field 2 mm long along the septotemporal axis, which may be regarded as a module for columnar organization, at a specific rostrocaudal level of the subiculum. The modules of the CA1a pyramidal neurons are disposed in the rostral part of the subiculum, those of the CA1c pyramidal neurons in the caudal part, and those of the CA1b pyramidal neurons in the middle part of the subiculum. The CA1 pyramidal neurons also participate in the construction of the lamellar organization in the hippocampus in that their axon branches run rostrocaudally following the stream of the alvear fibers. The CA1 pyramidal neurons in the dorsal rat hippocampus transfer the topographic map from field CA1 to the subiculum with reversed order in the lamellar direction. The topographical relationship is composed of partially shifted, overlapping slab-like modules. As a result, information conveyed through a lamella will diverge into the subiculum approximately 2 mm wide, and information through a group of lamellae 2 mm wide will converge upon single subicular neurons.

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PubMed1990

The distribution pattern of the sympathetic nerve fibers to the cerebral arterial system in rat as revealed by anterograde labeling with WGA-HRP.

To clarify the projection route and the expansion of the terminal plexus of the sympathetic nerve fibers innervating the cerebral arterial system in rat, we labeled the postganglionic fibers originating in the superior cervical ganglion and traced their entire course by anterograde labeling with wheat germ agglutinin-horseradish peroxidase. Sympathetic innervation of the internal cerebral artery by labeled fibers actually began just at the portion where it enters the intradural space, and innervated it up to the small pial arteries located in the subarachnoid space, but not the intracerebral arterioles. On the main arteries in the circle of Willis, bundles of nerve fibers ran parallel to the long axis of the vessels and branched perpendicularly their terminal twigs with regular intervals to form a rib-structure pattern. On the arterial branches derived from the circle of Willis, a fine nerve bundle and delicate terminal axons formed a meshwork instead of a rib-structure pattern. These observations confirmed the existence of differences in the distribution pattern of the nerve plexus, which strongly affects the strength and quality of vasoconstriction by sympathetic activation in each level of the cerebral arterial system.

Animals↗

PubMed1990

Appearance of retrogradely labeled neurons in the rat superior cervical ganglion after injection of wheat-germ agglutinin-horseradish peroxidase conjugate into the contralateral ganglion.

Injection of wheat-germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) into the superior cervical ganglion (SCG) of the rat results in accumulation of WGA-HRP in sympathetic postganglionic neurons in the contralateral SCG. The sympathetic pathways involved and the mechanism underlying the labeling were investigated. The labeling in neurons in the contralateral SCG was apparent 6 h after injection and increased in intensity with longer survival times. The number of labeled neurons reached 1300 at 72 h after the injection. Transection of the external (ECN) or internal carotid nerves (ICN) resulted in considerable reduction in the number of labeled neurons. Combined transection of both ECN and ICN virtually eliminated labeling in the contralateral SCG. This provides strong evidence that these two nerves are the major pathways for WGA-HRP transport out of the SCG. No labeling was observed in the contralateral SCG following injection of horseradish peroxidase (HRP). Therefore, it seems unlikely that a direct nerve connection exists between the bilateral ganglia. Instead, the labeling of contralateral SCG neurons appears to depend on the transneuronal transport capacity of WGA-HRP, which conveys the marker in an anterograde direction along the postganglionic fibers to terminals in sympathetic target organs, and then delivers it transneuronally to contralateral SCG neurons. We suggest that the sympathetic nerve fibers originating in the bilateral SCGs run intermingled and are in close contact in their peripheral target organs.

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PubMed1988

Three-dimensional analysis of the whole axonal arbors originating from single CA2 pyramidal neurons in the rat hippocampus with the aid of a computer graphic technique.

The axonal arborization of single pyramidal neurons in field CA2 and the rostral adjacent area of the rat hippocampus was studied with intracellular staining following the pressure microinjection of horseradish peroxidase (HRP) in combination with the immunoperoxidase technique, and was analyzed three-dimensionally with the aid of a computer system. The axonal arbors were composed of two types of axon branches, which were distinguished as the primary and secondary axon branches on the basis of morphological criteria. The axon branches in the ipsilateral hippocampus exhibited almost the contour of the dorsal hippocampus. The large amount of axon branches labeled with HRP in the stratum (str.) oriens of field CA1 was comparable to that in the str. radiatum of the field. The labeled axon branches in the dorsal hippocampus were not distributed uniformly in terminal regions but were focused on the caudolateral CA1a-b subfields. Most primary axon branches ran to a focus along the alvear fibers. The lamellar organization in the CA2 pyramidal neurons may be composed of axon branches running caudally and terminal branches forming a focus. The dense association fibers along the septotemporal axis may connect the lamellar organized circuits to each other. Axon branches in the septal nuclei of each hemisphere formed a rather flat plane. The commissural fibers of the CA2 pyramidal neurons seemed to form a symmetrical projection field in the contralateral side against the median plane. The axonal arbors and dendritic expansion of the pyramidal neurons shown in this study appeared to reveal the whole image of the single CA2 pyramidal neuron.

Animals↗

PubMed1988

Histochemical and electron microscopical demonstration of the sympathetic nerve fibers joining to the fourth and the sixth cranial nerves in rats.

The localization of sympathetic fibers on the floor of the cranium was studied in rats using amine fluorescence histochemistry, neuropeptide-Y (NPY) immunohistochemistry, and electron microscopy. The vast majority of amine fluorescent fibers joined the abducent nerve and were localized in the peripheral zone under the perineurium. After advancing along this nerve for some distance, the fibers diverged into many bundles that converged to form the cavernous plexus at a rostral end of the trigeminal ganglion. On the dorsal surface of the trigeminal ganglion, one or two medium-calibered fluorescent bundles ran inside or in close proximity to the trochlear nerve, while many small-calibered, brightly fluorescent bundles also extended longitudinally in the epidural connective tissue. In rats that had undergone nerve severance, NPY-immunoreactive fibers were detected at the cut ends of the abducent and trochlear nerve. The differing amounts of NPY accumulated at the rostral and the caudal stumps indicated the direction of the NPY-bearing fibers. Electron microscopy confirmed the presence of unmyelinated fibers in both the abducent and trochlear nerves.

Adrenergic Fibers↗

PubMed1988

An embryonic pineal body as a multipotent system in cell differentiation.

The differentiating potency of pineal cells from 8-day quail embryos was studied with cell culture. It was found that the differentiation of striated muscle fibres occurred abundantly in the pineal cells cultured in hypertonic culture conditions. Muscle nature of these fibres was confirmed by utilizing the antiserum against the striated muscle type creatine kinase (MM-CK). When CO2, NAHCO3, NaCl, KCl and MgCl2 were added in hypertonic concentrations, extensive myogenesis occurred in cultured pineal cells. Myogenesis in pineal cultures began as early as 2 days and, after 3 days in the medium with 75 mM additional NaCl, reached 100-fold when compared with that in the isotonic medium. Muscle fibres from pineal cells in culture were similar in morphology to the skeletal muscle fibres of mesodermal origin in situ. Myogenesis of pineal cells under hypertonic conditions was accompanied by the synthesis of a unique 56 x 10(3) Mr protein, which was not found in the intrinsic muscle cells. Clonal cell culture revealed that about 80% of clonable pineal cells were myogenic precursors. Pineal cells of 8-day quail embryos were not only myogenic but oculopotent (melanogenic and lentoidogenic) in cultures. This study examined whether multipotential progenitor cells with both potentials are present in the pineal or not. The results showed that at least 16% of all clonable pineal cells were multipotent precursors. The embryonic pineal is considered to be a typical multipotent system in parallel with the pigmented and neural retina, the neural crest and the teratocarcinoma.

Animals↗

PubMed1987

Intracranial trajectories of sympathetic nerve fibers originating in the superior cervical ganglion in the rat: WGA-HRP anterograde labeling study.

Intracranial trajectories of sympathetic nerve fibers originating in the superior cervical ganglion (SCG) in the rat were investigated by means of anterograde labeling following the injection of wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) into the unilateral SCG. The trajectory of the sympathetic fiber innervating the pineal gland and its continuing structures was found advancing along the abducent nerve, through the cavernous plexus, then along the trochlear nerve. Labeled sympathetic fibers showed two patterns of distribution in the blood vessels on the basal surface of the brain. The sympathetic fibers originating in the unilateral SCG were intermingled with those fibers from the contralateral SCG in the pineal gland, its continuing structures and the choroid plexus of the third ventricle as well as in the cerebral blood vessels.

Adrenergic Fibers↗

PubMed1987

Columnar organization in the subiculum formed by axon branches originating from single CA1 pyramidal neurons in the rat hippocampus.

An intracellular horseradish peroxidase study combined with immunoperoxidase techniques was carried out on hippocampal CA1 pyramidal neurons in the rat. Most axon branches originating from a single CA1 pyramidal neuron ran caudally and terminated in the subiculum. The individual axon branches of the single pyramidal neurons bifurcated repeatedly in the subiculum and finally formed a slab-like or columnar terminal arborization (250-300 microns wide, 500-550 microns high and 1.8-2.2 mm long). The present results suggest, in association with other data, that the CA1 pyramidal neurons receive afferent information through lamellar organized connections and they send efferent information to the subiculum through columnar organized connections.

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PubMed1985

Oculopotency of embryonic quail pineals as revealed by cell culture studies.

Pineal bodies from 8-day-old quail embryos were dissociated and cultured in order to examine their potency for differentiation under in vitro conditions. Polygonal pigment cells and lentoid bodies started to differentiate after about 2 and 4 weeks, respectively. Lentoid bodies were shown immunologically to contain all classes of crystallins. The results indicate that embryonic pineal cells of avian species retain 'oculopotency' to differentiate into several types of ocular cells.

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