Biomedical subjects

S Shiosaka

Publications and source records attributed to S Shiosaka.

At least 19 recordsLinked to original sources

PubMed1992

Localization of basic fibroblast growth factor-like immunoreactivity in the rat brain.

The immunohistochemical localization of basic fibroblast growth factor (bFGF) was studied in the adult rat brain, using a specific antibody against a synthetic bFGF fragment (the N-terminal 12 residues). Widespread but uneven regional localization of bFGF-like immunoreactive neurons and fibers was observed. Ependymal cells were also stained. The immunoreactive neurons were found in the cerebral cortex, olfactory bulb, septum, basal magnocellular nuclei, thalamus, hypothalamus, globus pallidus, hippocampus, amygdala, red nucleus, central gray of the midbrain, cerebellum, dorsal tegmental area, reticular formation, cranial motor nuclei and spinal cord. Immunoreactive fiber bundles and nerve terminals were also detected. These results indicate that bFGF is produced by or present in a specific neuronal cell population of the central nervous system.

Amino Acid Sequence↗

PubMed1992

Basic fibroblast growth factor-like immunoreactivity in the trigeminal proprioceptive and motor systems.

Basic fibroblast growth factor (bFGF) isolated from the brain and pituitary, has been shown to induce cell divisions in a variety of cell types. It also acts as a potent stimulator of angiogenesis, and it is important in the survival of several types of cultured neurons. Despite considerable information on the functions of bFGF, there is incomplete knowledge about the ways in which it reaches remote tissues and its subcellular localization in the adult brain. Here we report our findings that a certain population of neurons with free ribosomes and rough endoplasmic reticulum immunoreactive for bFGF in the mesencephalic nucleus of the trigeminal nerve sends proprioceptive fibers to muscle spindles in the masseter muscle, and immunoreactive axons to the trigeminal motor nucleus to form synapses with the bFGF-containing motoneurons whose axons further constitute myoneural junctions in the periphery. Moreover, some bFGF neurons contain electron dense immunoreaction deposits in the euchromatin but not in the heterochromatin of the nucleus. These findings suggest that endogenous bFGF is transported within nerve processes and functions in mature neuronal circuits subserving the masseteric reflex arcs, and that bFGF is produced in free ribosomes and/or rough endoplasmic reticulum and is transported into the genetically active euchromatin as well.

Animals↗

PubMed1992

Increase of basic fibroblast growth factor immunoreactivity and its mRNA level in rat brain following transient forebrain ischemia.

We examined the time course of basic fibroblast growth factor (bFGF) immunoreactivity and its mRNA level mainly in the hippocampus after transient forebrain ischemia using immunohistochemistry, enzyme immunoassay (EIA), Western blot analysis and in situ hybridization. Neuronal death in the hippocampal CA1 subfield was observed 72 h after 20 min of ischemia. The number of bFGF-immunoreactive(IR) cells increased 48 h-5 days after ischemia in all hippocampal regions. At 10 and 30 days, the bFGF-IR cells in the CA1 subfield had further increased in numbers and altered their morphology, enlarging and turning into typical reactive astrocytes with the advancing neuronal death in that area. In contrast, the number of bFGF-IR cells in other hippocampal regions had decreased 30 days after ischemia. The EIA study showed a drastic increase in bFGF levels in the hippocampus 48 h after ischemia (150% of that in normal rat) which was followed by further increases. In Western blot analysis, three immunoreactive bands whose molecular weights correspond to 18, 22 and 24 kDa were observed in normal rat and ischemia increased all their immunoreactivities. In the in situ hybridization study of the hippocampus, bFGF mRNA positive cells were observed in the CA1 subfield in which many bFGF-IR cells existed after ischemia. These data demonstrate that transient forebrain ischemia leads to an early and strong induction of bFGF synthesis in astrocytes, suggesting that the role of bFGF is related to the function of the reactive astrocytes which appear following brain injury.

Animals↗

PubMed1992

Attempts to make models for Alzheimer's disease.

Profound reductions in cortical acetylcholine levels together with degeneration of cholinergic neurons in the basal forebrain have been reported in patients with Alzheimer's disease. A similar loss of the cholinergic neurons of the basal forebrain and impairment of learning and memory occur in animals injected with a nerve growth factor-diphtheria toxin conjugate, suggesting that this animal model is suitable to analyze cholinergic roles on learning and memory processes, and also the pathogenesis of Alzheimer's disease. In addition, animal models constructed by electrolytic or neurotoxic lesioning of the basal magnocellular nucleus, and models made by transgenetic technology were described.

Alzheimer Disease↗

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

Localization of basic FGF-like immunoreactivity in the hypothalamo-hypophyseal neuroendocrine axis.

We examined the localization of basic fibroblast growth factor (basic FGF) in the adult rat brain by immunohistochemical and Western blotting analysis using a specific antibody against a synthetic basic FGF fragment (N-terminal 12 residues). The antibody did not cross-react with acidic FGF. Basic FGF-like immunoreactivity was located exclusively in the neuronal elements and had very heterogeneous distribution. Immunoreactive cell bodies were observed in the paraventricular, supraoptic and circular nuclei of the hypothalamus. Numerous immunoreactive neuronal processes originating from these basic FGF-positive cells extended lateroventrally and then caudally to the internal layer of the median eminence. In addition, the neurohypophysis contained a significant number of basic FGF-like immunoreactive fibers. Western-blotting analysis revealed that the hypothalamus and the hypophysis contained a main band of basic FGF immunoreactive with an apparent molecular weight of 17 kDa. These results show that the hypothalamo-hypophyseal neuroendocrine pathway contains basic FGF.

Amino Acid Sequence↗

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

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

Long-term survival of grafted cells, dopamine synthesis/release, synaptic connections, and functional recovery after transplantation of fetal nigral cells in rats with unilateral 6-OHDA lesions in the nigrostriatal dopamine pathway.

In animal models of hemi-Parkinson's disease, survival of grafted nigral cells, their synaptic connections, dopamine (DA) synthesis/release, and recovery from motor disturbances were investigated, and these were compared among 3 groups of animals raised for 3 months, 1 year and 2 years after the transplantation. Fetal nigral DAergic cell suspensions were transplanted in the ipsilateral caudate nucleus of rats with unilateral 6-OHDA lesions in the nigrostriatal DA pathway. Motor disturbances, assessed by methamphetamine-induced rotation, recovered partly in the 2nd week, significantly in the 4th week after the grafting, and remained stable thereafter. Many tyrosine hydroxylase (TH)-positive cells were detected along the grafting tracks. The number of TH-positive cells was similar in the 3 groups of animals. These TH-positive cells made synaptic connections in the host caudate. By in vivo microdialysis measurement, extracellular DA, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) around the grafted sites recovered to 30-100% of those of controls. No significant differences were observed in the concentration of DA, DOPAC and HVA among 3 groups of animals. They also responded to methamphetamine loading though the magnitudes were smaller. Using a TH cDNA probe, TH-positive cells were found to express TH mRNA in in situ hybridization-autoradiographic analysis. Data indicate that grafted fetal DAergic cells survive, synthesize and release DA, make synaptic connections in the host brain and ameliorate motor disturbances for over 2 years. There were no differences in these parameters among the 3 groups of animals, and no untoward side effects were observed even at 2 years after the grafting. Thus it was confirmed that the grafting of neuronal cells into the brain is a promising approach to restore disturbed function.

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

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

Electron microscopic observation of calcitonin gene-related peptide-like immunoreactivity in the organ of Corti of the rat.

Calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRP-IR) nerve terminals in the organ of Corti of rats were studied by light and electron microscopy. Surface preparation of the organ of Corti were immunostained using anti-CGRP antiserum for avidin-biotin immunohistochemistry. Dense CGRP-IR fiber bundles were observed by light microscopy in the inner spiral bundles, tunnel spiral bundles and outer spiral bundles. Electron microscopic analysis indicated that CGRP-IR fibers belong to efferent nerves. In the inner spiral bundles, the CGRP-IR fibers showed a direct contact mainly with non-immunoreactive afferent fibers. Some CGRP-IR nerve endings in the inner spiral bundles formed contacts directly with inner hair cells. In the outer spiral bundles, CGRP-IR fibers formed synaptic contacts exclusively with the outer hair cells. It should be noted that the number of synapses of CGRP nerve endings with outer hair cells varied depending upon the sub-row: a falling gradient in number occurred along the inner-outer axis. Our results suggest that CGRP acts as an efferent neuromodulator in the organ of Corti.

Animals↗

PubMed1990

Presence of sex difference of cytochrome P-450 in the rat preoptic area and hypothalamus with reference to coexistence with oxytocin.

Localization of female type cytochrome P-450 (F1) in the preoptic area and hypothalamus of the rat was examined immunocytochemically using antiserum against purified hepatic P-450 (F1). This antiserum recognizes both P-450 (F1) and P-450 (M3). Western immunoblotting using the antiserum demonstrated that female rat brain contains P-450 (F1) but not P-450 (M3), since microsomes from the brain and liver displayed only one immunoreactive band at 50 kD, coinciding with that of P-450 (F1) purified from female rat liver. On the other hand, the male brain has P-450 (M3) but not P-450 (F1), as liver- and brain-derived microsomes produced single band at 49 kD, which represents a mol. wt. identical to that of P-450 (M3) extracted from male rat liver. These results indicate that P-450 (F1)-like immunoreactivity (LI) occurs in the female rat brain, while P-450 (M3)-LI takes place in the male rat brain. Immunocytochemical analysis further demonstrated the detailed cellular localization of these two P-450-LIs in the preoptic area and hypothalamus of female and male rats. Localization of P-450 (F1)-LI in the female rat hypothalamus resembled that of P-450 (M3)-LI in the male rat hypothalamus. Magnocellular neurosecretory neurons in the paraventricular nucleus and supraoptic nucleus were labeled and were found to contain oxytocin but lack vasopressin when serial sections of these areas were analyzed. In addition, groups of immunoreactive cells were seen in the median preoptic nucleus, medial and lateral preoptic area, caudal portion of the bed nucleus of the stria terminalis, lateral hypothalamus at the level of the paraventricular nucleus, periventricular zone from the preoptic area to the paraventricular nucleus, and parvocellular portion of the paraventricular nucleus.

Animals↗

PubMed1990

Transient expression of somatostatin mRNA in the auditory system of neonatal rat.

Postnatal changes of preprosomatostatin mRNA expression in the rat auditory system were examined using in situ hybridization histochemical techniques. It was found that during postnatal days 1 and 2 most of the neurons in the dorsal and ventral cochlear nuclei, and large numbers of neurons in the inferior colliculus, paralemniscal nucleus, and lateral lemniscal nucleus, expressed somatostatin mRNA with a strong intensity. During postnatal development a marked decrease in the number and intensity of neurons expressing somatostatin mRNA was seen. These findings suggested that somatostatin was actively produced in the cochlear nuclei at a very early stage but that production later became reduced or ceased during postnatal ontogeny.

Aging↗

PubMed1989

An attempt to cause the selective loss of the cholinergic neurons in the basal forebrain of the rat: a new animal model of Alzheimer's disease.

In the present study, we attempted to develop a new animal model of Alzheimer's disease. Injections of a nerve growth factor (NGF)-diphtheria toxin conjugate into the cerebral cortex resulted in a marked ipsilateral reduction of cholinergic neurons in the horizontal limb of the diagonal band and basal magnocellular nucleus of rats. No effects could be seen in the cholinergic neurons located in the laterodorsal tegmental nucleus intrinsic cortical cholinergic neurons, and catecholaminergic locus coeruleus neurons. Injections of the conjugate into the caudoputamen failed to cause changes in the striatal cholinergic neurons. Since our method could selectively reduce cholinergic neurons in the basal forebrain without damage to the non-cholinergic neurons or passing fibers in this nucleus, this animal model method seems to be very useful in analyzing the pathogenesis of Alzheimer's disease or in examining the function of acetylcholine in the cholinergic neurons of the basal forebrain.

Alzheimer Disease↗

PubMed1989

Gap junction protein in rat hippocampus: light microscope immunohistochemical localization.

An affinity-purified antibody against a 27-kD rat liver gap-junctional protein (GJP) was used to determine the distribution of GJP immunoreactivity in sections of rat hippocampus. Four heterogeneously distributed GJP-immunostaining patterns were observed. The two most common were punctate immunoreactive elements ranging in size from 0.3 to 0.7 microns and networks of immunoreactive varicose fibers coursing in a variety of directions within the various hippocampal layers and ranging in length from a few microns up to 200 microns. The density of punctate immunostaining was highest within a portion of the stratum pyramidale, at the border between the stratum pyramidale and stratum oriens, and at the border between the molecular and granule cell layers of the dentate gyrus. Moderate to low densities were observed in other hippocampal areas. Immunoreactive fibers were most concentrated within the border portions of the stratum pyramidale and oriens, moderately distributed in the stratum radiatum and the remaining part of the stratum oriens, and sparse in the alveus. In the dentate gyrus, fiber networks were most evident at the border between the granule cell and molecular layers and very unevenly distributed in the molecular layer. The two other patterns observed included intense filamentous immunostaining within a small number of neuronal perikarya located mainly in the stratum pyramidale of areas CA2 and CA3, but rarely in area CA1 or the dentate gyrus, and diffuse immunostaining of small cell bodies dispersed throughout the hippocampus but most numerous in the vicinity of the stratum pyramidale and in the alveus. All of these immunostaining patterns were seen at all rostrocaudal hippocampal levels. These results suggest that if GJP-immunoreactive fibers and neurons observed in the hippocampus have the capacity to form gap junctions, then electrotonic transmission may constitute an important means of information processing within this structure.

Animals↗

PubMed1989

Gap junction protein in rat hippocampus: correlative light and electron microscope immunohistochemical localization.

Immunohistochemical techniques and an affinity-purified antibody directed against the 27-kD gap-junctional protein (GJP) from rat liver were used to determine the ultrastructural localization of GJP in the rat hippocampus. At the light microscope level, dense GJP immunoreactivity having a stringlike appearance was seen in a very small percentage of medium-sized neuronal somata located in the stratum pyramidale, and diffuse immunostaining was seen in many small cell bodies in the stratum pyramidale, stratum oriens, and the alveus. Abundant GJP-immunoreactive (GJP-IR) varicose fibers were observed in the strata pyramidale, radiatum, and oriens but were less concentrated in the alveus. Numerous punctate GJP-IR elements were observed in all hippocampal layers. Upon EM analysis, GJP-IR neuronal somata in the stratum pyramidale were found to be, without exception, nonpyramidal neurons as judged by such distinguishing features as their fusiform perikarya, indented nucleus, and well-developed rough endoplasmic reticulum (RER). Immunostaining within these cells was largely localized to the Golgi apparatus and associated vesicular components. Small, diffusely GJP-IR cells were identified ultrastructurally as protoplasmic and fibrous astrocytes. Immunostaining within these cells was localized to the Golgi apparatus, RER, and small, ribosomelike bodies 15-25 nm in diameter. Among neuronal processes GJP immunoreactivity was found within dendrites, axons, and axonal terminals. The latter structures contained numerous GJP-IR vesicles having an average diameter of about 40 nm. A frequent observation indicating some degree of specificity of the anti-GJP antibody employed here was immunostaining of typical gap junctions between dendrites and, more commonly, between processes of glial cells. Occasionally, however, GJP-IR dendrodendritic, axodendritic, and axoaxonic contacts were found that could be considered, at best, as being gap-junction-like (gj-L). In these cases, asymmetric immunostaining of adjacent plasma membranes forming gj-L structures was not uncommon. These results confirm the existence of gap junctions between dendrites in the rat hippocampus and demonstrate that GJP immunoreactivity on cytoplasmic membranes is restricted either to typical neuronal and glial gap junctions or to gj-L structures at circumscribed sites of contact between various types of neuronal elements where GJP may contribute to a novel mechanism of neural communication.

Animals↗