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Biomedical subjects

M Tohyama

Publications and source records attributed to M Tohyama.

At least 379 records · Page 21Linked to original sources
PubMed1988

Projection of neurotensin-like immunoreactive neurons from the lateral parabrachial area to the central amygdaloid nucleus of the rat with reference to the coexistence with calcitonin gene-related peptide.

The origin of neurotensin-like immunoreactive (NTI) fibers in the central amygdaloid nucleus (AC) in the rat was examined using indirect immunofluorescence and retrograde tracing combined with immunocytochemistry. Destruction of the external subdivision of the lateral parabrachial nucleus, which contains a group of NTI neurons, resulted in a marked reduction of these fibers in the ipsilateral AC, which suggests that most of these fibers are of extrinsic origin. This was also supported by the finding that injection of fast blue dye into the AC labeled many neurons in the external subdivision of the lateral parabrachial nucleus ipsilaterally, and that simultaneous treatment with antiserum against NT stained some of these neurons. Subsequent immunohistochemical staining of alternate sections revealed that many of these NTI neurons were also labeled by calcitonin gene-related peptide antiserum.

Amidines↗
PubMed1988

AF64A(ethylcholine aziridinium ion)-induced basal forebrain lesion impairs maze performance.

Rats were given bilateral injections of ethylcholine aziridinium ion, AF64A (1 nmol/side) into the basal forebrain (BF). One month later, choline acetyltransferase activity was reduced by 25% in the frontal cortex (FC). There was a marked decrease in cortical uptake of [3H]choline, but [3H]GABA and [3H]dopamine uptake was not affected by the injection. Histological analysis confirmed that this dose of AF64A caused acetylcholinesterase staining in the FC to disappear. Acquisition and retention of a T-maze task were impaired in the rats with BF lesions one month after the injection. Acquisition of the water-filled multiple T-maze task was also impaired by AF64A. These observations suggest that the cholinergic component in the BF is involved in spatial memory.

Acetylcholinesterase↗
PubMed1988

A noxious stimulus induces the preprotachykinin-A gene expression in the rat dorsal root ganglion: a quantitative study using in situ hybridization histochemistry.

Using in situ hybridization histochemistry, we examined the biosynthesis of the preprotachykinin-A (PPTA) mRNAs, which code for substance P (SP) and also a related peptide, substance K (SK), in the rat dorsal root ganglion (DRG). The animals were injected with a small amount of formalin in the right hindpaw for nociceptive chemical stimulation. Analysis of hybridization signals in the emulsion autoradiography showed that the lumbar-5 DRG neurons expressing PPTA mRNAs were significantly increased in number and signal intensity on the formalin-injected side. Such elevation of the PPTA mRNA expression in the DRG was observed as early as 3 h after formalin injection. These results show that the expression of the PPTA gene is activated by chemogenic noxious stimuli.

Animals↗
PubMed1988

Neurotensin-containing projections from the retrosplenial cortex to the anterior ventral thalamic nucleus in the rat.

The neurotensin-containing projections from the retrosplenial cortex to the anterior ventral thalamus were demonstrated by electrolytic lesion studies and fluorescent retrograde tracing combined with immunocytochemistry. Three-to-five-day-old rats were used, because the immunoreactivity of neurotensin fibers in anterior ventral thalamus was the highest at this age. When neurotensin-containing neurons located in layer VI of the retrosplenial cortex were unilaterally destroyed by applying an electrolytic current to the retrosplenial area, the neurotensin fibers in the ipsilateral anterior ventral thalamus decreased dramatically. Unilateral injection of a fluorescent retrograde tracer, Fast Blue, into the anterior ventral thalamus, labeled neurons in the ipsilateral retrosplenial cortex, and many of these cells also had neurotensin-like immunoreactivity. These results suggested that a major origin of the neurotensin fibers in the anterior ventral thalamus was in the ipsilateral retrosplenial granular cortex.

Amidines↗
PubMed1988

Ontogeny of the calcitonin gene-related peptide in the nervous system of rat brain stem: an immunohistochemical analysis.

The ontogeny of the calcitonin gene-related peptide in the neuron system of the rat brain stem was investigated by means of the indirect immunofluorescence technique. Calcitonin gene-related peptide-like immunoreactivity was first detected in the fibers of the nucleus of spinal tract trigeminal nerve on gestational day 18, and thereafter appeared gradually in various brain stem areas such as in the fibers of the solitary tract, gracile nucleus, cuneate nucleus, inferior colliculus, superior colliculus, medial geniculate nucleus and in the neurons of the hypoglossal nucleus, facial nucleus, superior olive, parabrachial area, superior colliculus and peripeduncular nucleus. In colchicine-untreated animals, the immunoreactive fibers increased in number and reached adult level by postnatal day 14, whereas the number of cells reached a maximum between postnatal days 2 and 6 and then decreased in number and immunoreactivity or disappeared, except in some areas such as the superior olive and peripeduncular nucleus, which showed the same immunoreactivity as for adult animals. With colchicine treatment, calcitonin gene-related peptide-like immunoreactive cells were found in more areas of the brain stem such as the abducens nucleus, parabigeminal nucleus, principal oculomotor nucleus, trochlear nucleus and central gray, along with the nuclei which had shown calcitonin gene-related peptide immunoreactivity in the untreated animals. However, the neurons in the inferior olive showed a different ontogenetical pattern of calcitonin gene-related peptide of immunoreactivity. Immunoreactivity disappeared completely by postnatal day 21 in both colchicine-untreated and -treated animals.

Aging↗
PubMed1988

Localization of glycine receptors in the rat central nervous system: an immunocytochemical analysis using monoclonal antibody.

The localization of glycine receptors was immunocytochemically examined in the rat brain using a monoclonal antibody against the affinity-purified glycine receptor. Glycine receptors were concentrated in the lower brainstem, whereas no immunoreactivity was observed in the diencephalon and forebrain except in a few diencephalic nuclei. The highest density of receptors was found in the cranial motor nuclei, reticular formation, parabrachial area, dorsal and ventral cochlear nuclei, and dorsal and ventral tegmental nuclei. Differences were observed in the distribution of immunoreactive elements in the various brain regions. In the cerebellar cortex, the immunoreactivity was exclusively seen along the dendrites of the Purkinje cells. On the other hand, glycine receptors were detected on the cellular membrane of the soma of the cochlear nuclei, trigeminal motor nucleus, parabrachial area, lateral reticular nucleus, dorsal nucleus of the lateral lemniscus, cerebellar nuclei, trigeminal spinal nucleus, anterior horn and reticular formation. In other regions, the receptors were evenly distributed throughout the neuropil.

Animals↗
PubMed1988

Co-localization of neurotensin- and cholecystokinin-like immunoreactivities in catecholamine neurons in the rat dorsomedial medulla.

Co-localization of neurotensin and cholecystokinin in tyrosine hydroxylase-containing neurons in the nucleus tractus solitarius of the rat was demonstrated by immunocytochemistry with fluorescent double-staining combined with the peroxidase-antiperoxidase method. Co-localization of neurotensin/tyrosine hydroxylase or cholecystokinin/tyrosine hydroxylase was consistently found in small neurons in the region dorsomedial to the tractus solitarius at the level of the area postrema with high percentages of co-existence: 91.0% tyrosine hydroxylase-immunoreactive neurons contained neurotensin and 91.1% cholecystokinin, suggesting that they represent the same neurons. Accordingly, co-localization of neurotensin and cholecystokinin was assessed on tyrosine hydroxylase-containing neurons bisected into two adjacent sections, and then identified in a certain number of the catecholamine neurons in this region. Furthermore these catecholamine neurons exhibited immunoreactivity for an adrenaline-synthesizing enzyme, phenylethanolamine N-methyltransferase. It was concluded that catecholamine, in particular adrenaline, neurons, characterized by co-localization of neurotensin and cholecystokinin, established a distinct subpopulation in the catecholaminergic system in the dorsomedial medulla of the rat.

Animals↗
PubMed1988

Evidences for the coexistence of substance P, neurotensin and calcitonin gene-related peptide in single neurons of the external subdivision of the lateral parabrachial nucleus of the rat.

Immunocytochemical double staining analysis revealed that most of the substance P-like immunoreactive neurons in the external subdivision of the lateral parabrachial nucleus of the rat contained neurotensin. Immunohistochemical staining of alternate consecutive sections showed that many of these neurons also contained calcitonin gene-related peptide.

Animals↗
PubMed1988

Immunohistochemical demonstration of beta-adrenoreceptor in the rat brain--with reference to the central control of blood pressure.

Using anti-beta 2-adrenoreceptor antibody, we examined immunohistochemically the localization of adrenoreceptor in the rat central nervous system at both lightmicroscopic and electronmicroscopic level. In the areas which are known to be involved in the control of blood pressure, such as the hypothalamus, the nucleus of the solitary tract and the locus coeruleus, there were a number of adrenoreceptor-like immunoreactive (ADR-IR) structures. They were mainly associated with cellular surface of the neuron. However, those localized within the cytoplasm or the nerve fiber were also observed. Immunoelectron microscopic analysis revealed that the ADR-IR structures were associated with post-synaptic density and cytoplasmic organella (endoplasmic reticulum, vesicle). Ultrastructural feature of the ADR-IR fiber was characterized by the synaptic vesicles with immunoreaction products. In addition, we detected that the running pattern of the ADR-IR fibers was often quite similar to that of tyrosine hydroxylase-immunoreactive (i.e. catecholaminergic) fibers. These findings suggest the presence of the presynaptic autoreceptor. In the present study, we have clearly demonstrated the cellular and subcellular localization of adrenoreceptors in the areas related to blood pressure control immunocytochemically. These results suggest the immunocytochemical method should be quite useful for further investigation of the CNS control of blood pressure.

Animals↗
PubMed1988

Selective loss of retinal ganglion cells in albino avian glaucoma.

Retinal ganglion cell loss was investigated in the retinae of albino quails before and after the development of glaucoma. The isodensity maps of ganglion cells, the total number of ganglion cells, and the histograms of the cell size in the central region of the retina were similar between albino quails without glaucoma and pigmented quails. However, ganglion cells in the intermediate and peripheral regions of the albino quails retina without glaucoma were significantly smaller than those of the pigmented quail retina. In albino quails with moderate glaucoma in 3 months of age, 11% to 55% of all the retinal ganglion cells had disappeared, with the loss of medium-sized cells (30-60 micron2 occurring earlier than that of small and large cells. In albino quails with advanced glaucoma, there was marked cupping around the optic nerve head, and only small ganglion cells remained in the ganglion cell layer.

Albinism↗
PubMed1987

Corticotropin-releasing factor-like immunoreactive nerve fibers in the rat superior cervical ganglion and their fine structures.

The existence of nerve fibers containing corticotropin-releasing factor (CRF)-like immunoreactivity (CRFI) in the rat superior cervical ganglion (SCG) was demonstrated by using immunocytochemistry. They were found to be extrinsic in origin, because no CRFI neurons were seen in the SCG and decentralization resulted in the disappearance of CRFI fibers in the SCG on the operated side. These findings were also confirmed by immunoelectron microscopic analysis; CRFI fibers contained a number of small clear synaptic vesicles but were devoid of large granular and agranular vesicles. These morphological characteristics are identical to those of the preganglionic fibers. The present immunoelectron microscopic analysis revealed that most of the CRFI fibers in the SCG make synaptic contact predominantly with the dendrites of the principal cells, partly with their somas and rarely with a non-CRFI terminal. Thus, the present study provides direct morphological evidence that CRF directly influences the function of the principal cells of the SCG and that CRFI fibers are preganglionic.

Animals↗
PubMed1987

Coexistence of substance P- and enkephalin-like peptides in single neurons of the rat hypothalamus.

The distribution of substance P- and enkephalin-like immunoreactivity in single cells were examined by the double immunofluorescence method. Substance P- and leucine-enkephalin-like compounds coexisted within individual neurons of some hypothalamic areas such as the medial preoptic area, anterior hypothalamic area, perifornical area, lateral hypothalamic area, premammillary nuclei and posterior hypothalamic nucleus, although they did not coexist in the majority of immunoreactive cells.

Animals↗
PubMed1987

Two discrete enkephalinergic neuron systems in the superior cervical ganglion of the guinea pig: an immunoelectron microscopic study.

Leucine-enkephalin (L-ENK)-like immunoreactive (L-ENKI) structures in the superior cervical ganglion (SCG) were first examined by using immunoelectron microscopy. L-ENKI neurons formed cell clusters and were small. They were filled with large granular or agranular vesicles and small electron lucent vesicles, and had nuclei that lacked a nucleolus. Since these morphological characteristics are identical to those of the small intensely fluorescent (SIF) cells, L-ENKI cells seemed to be a kind of SIF cell. Two types of L-ENKI fibers were identified, a large type filled with large granular or agranular vesicles and a small type filled with small electron lucent vesicles. The large fibers were located near the L-ENKI perikarya and often could be traced directly to the soma. These fibers remained intact after decentralization of the SCG. These findings indicate that the large L-ENKI fibers are processes of L-ENKI SIF cells. The fibers showed a close apposition to the blood vessels and rarely formed synaptic contact with dendrites of the principal cells. On the other hand, the small L-ENKI fibers were found to originate outside the SCG, because they disappeared after decentralization of the SCG. These L-ENKI fibers frequently formed synaptic contact with the dendrites of the principal cells. Thus, the present study demonstrated the presence of two discrete L-ENKI neuron systems in the SCG of the guinea pig, one an intrinsic SIF system and the other an extrinsic L-ENKI system.

Animals↗