Biomedical subjects

Y Ibata

Publications and source records attributed to Y Ibata.

At least 73 records · Page 4Linked to original sources

PubMed1994

Rehydration process from salt-loading: recovery of vasopressin and its coexisting galanin, dynorphin and tyrosine hydroxylase immunoreactivities in the supraoptic and paraventricular nuclei.

Salt-loading induces profound metabolic changes in magnocellular vasopressin (AVP)-containing neurons, including changes in levels of coexisting peptides and tyrosine hydroxylase (TH). Although many studies have been conducted on salt-loading, little information is available on the recovery processes following its cessation. In the present study, we investigated the changes in AVP, galanin (Gal), dynorphin B (Dyn-B), and TH immunoreactivities in the rat supraoptic nucleus (SON) and paraventricular nucleus (PVN) by immunocytochemistry using specific antisera against these substances. Salt-loading was induced in rats by dissolving 2% NaCl in their drinking water for 7 days. These animals were then allowed free access to fresh water for 2, 4, or 7 days prior to sacrifice. In the SON at the 7th day of salt-loading, AVP, Gal and Dyn-B immunoreactivities decreased in contrast to the marked increase in TH-immunoreactivity compared to those of control rats with free access to water. After a recovery period with free access to water, AVP and Gal immunoreactivities increased with time and returned to the control level at the 7th day. However, Dyn-B immunoreactivity did not recover even at the 7th day. Dehydration-induced TH-immunoreactive neurons almost disappeared at the 7th day. Immunoreactivities for these substances in the PVN showed a similar time course as that in the SON. These findings suggest that AVP and substances coexisting with it change with different time courses in magnocellular neurons following cessation of salt-loading.

Animals↗

PubMed1994

In situ hybridization histochemistry of vghm1f mRNA in the rat suprachiasmatic nucleus: co-localization with vasopressin/neurophysin and VIP/PHI.

The expression of vgf gene, first isolated as a gene induced by nerve growth factor in PC12 cells, was investigated in neurons of the suprachiasmatic nucleus (SCN) by in situ hybridization. In the rat forebrain, the vgf mRNA was found most densely in the SCN. Neurons which express vgf mRNA were found both in the dorsomedial and ventrolateral subdivisions. Double-labeling of vgf in situ hybridization and peptide immunocytochemistry demonstrated that vgf mRNA was expressed in most vasopressin- and neurophysin-immunoreactive neurons in the dorsomedial part and in vasoactive intestinal peptide (VIP)- and peptide histidine isoleucine amide (PHI)-immunoreactive neurons in the ventrolateral part. These findings suggest that vgf is a highly expressed gene in both vasopressin/neurophysin neurons and VIP/PHI neurons which were speculated to be involved in the generation and entrainment of circadian rhythm.

Animals↗

PubMed1994

GRP immunoreactivity shows a day-night difference in the suprachiasmatic nuclear soma and efferent fibers: comparison to VIP immunoreactivity.

Day-night variations of gastrin releasing peptide (GRP) in the neuronal somal area of the SCN and the nearby region on the anterior hypothalamic area (AHA) where GRP fibers project, were examined by semiquantitative immunocytochemistry, and compared with those of vasoactive intestinal peptide (VIP). Both in the SCN and AHA, GRP immunoreactivity was higher during the day than at night, although VIP immunoreactivity was higher at night than during the day. These observations suggest that, although they are produced in the same ventrolateral subdivision of the SCN and, in part, coexist in the same neurons [13], the day-night changes of GRP and VIP immunoreactivity are in the opposite direction to each other.

Animals↗

PubMed1994

Pituitary adenylate cyclase-activating polypeptide (PACAP)-like immunoreactive neuronal elements in rat hypothalamus and median eminence with special reference to morphological background of its effect on anterior pituitary--light and electron microscopic immunocytochemistry.

Pituitary adenylate cyclase-activating polypeptide-like immunoreactive (PACAP-LI) neuronal elements in the rat hypothalamus including the median eminence (ME) were investigated by light and electron microscopic immunocytochemistry. PACAP-LI neuronal perikarya with well-developed cell organelles and dense granules were distributed mainly in the magnocellualr portion of the paraventricular nucleus and throughout the entire supraoptic nucleus. In the ME, numerous PACAP-LI neuronal processes were found in the internal layer (IL), and immunoreactive terminals containing dense granules, vesicles and mitochondria were detected around portal capillaries which penetrated into the IL from the external layer. Thereafter, PACAP is released into the portal capillaries in the IL, transported to the anterior pituitary and plays a role in the stimulation of adenylate cyclase of anterior pituitary cells.

Adenylyl Cyclases↗

PubMed1994

Serotonin depletion by p-chlorophenylalanine decreases VIP mRNA in the suprachiasmatic nucleus.

The influence of serotonergic inputs on the levels of vasoactive intestinal peptide (VIP) mRNA in the rat suprachiasmatic nucleus (SCN) was examined by in situ hybridization combined with morphometrical analysis. Depletion of serotonin by p-chlorophenylalanine methyl ester (300 mg/kg i.p. daily for 3 days) caused a marked decrease in VIP mRNA signal levels in the ventrolateral part of the SCN. This finding suggests that serotonergic input controls VIP production at the mRNA level.

Animals↗

PubMed1994

Co-existence of PACAP and nitric oxide synthase in the rat hypothalamus.

The possible co-existence of pituitary adenylate cyclase-activating polypeptide (PACAP)-38 and nitric oxide synthase (NOS) in the rat hypothalamus was examined by a combination of PACAP-immunocytochemistry and NADPH-diaphorase histochemistry. Virtually all PACAP-38-immunoreactive neurones in the paraventricular and supraoptic nuclei exhibited NADPH-diaphorase activity. Since NADPH-diaphorase activity was identical to NOS-immunoreactivity in the magnocellular neurosecretory neurones, this finding indicates that the PACAP neurones synthesize NO.

Amino Acid Oxidoreductases↗

PubMed1994

Autoradiographic distribution of [3H]YM-09151-2, a high-affinity and selective antagonist ligand for the dopamine D2 receptor group, in the rat brain and spinal cord.

We determined the regional distribution of the dopamine D2 receptor group in the rat central nervous system by quantitative receptor autoradiography with a high-affinity and selective antagonist, [3H]YM-09151-2. Saturation and competition experiments demonstrated that the binding of [3H]YM-09151-2 to striatal sections was saturable (Bmax = 37.3 fmol/section), of high affinity (Kd = 0.315 nM), and was inhibited selectively by prototypic D2 ligands. The anatomical localization of binding sites was determined by comparison of autoradiograms and the original 3H-ligand-exposed sections stained with cresyl violet. Very high levels of [3H]YM-09151-2 binding were found in the caudate-putamen, nucleus accumbens, tuberculum olfactorium and the insula of Calleja, to each of which midbrain dopaminergic neurons project densely. High levels of binding were also observed in other regions rich in dopaminergic neurons and fibers including the glomerular layer of the olfactory bulb, the intermediate lobe of the pituitary, lateral septum, substantia nigra pars compacta, interfascicular nucleus, dorsal raphe nucleus, locus coeruleus, and nucleus of the solitary tract. Some regions poor in dopaminergic innervation, however, had high levels of [3H]YM-09151-2 binding including the molecular layer of gyrus dentatus, all layers of CA1 and the nonpyramidal layer of CA4 of hippocampus, and the deeper layer of medial entorhinal cortex. Motor neurons present in brainstem motor nuclei and spinal ventral horn were also strongly labeled. Neocortical, cerebellar, and thalamic regions had low levels of binding, except lobules 9-10 of the cerebellum, the olivary pretectal nucleus, zona incerta and lateral mammillary nucleus, in which moderate to high levels of binding were detected. Our findings concerning the widespread but region-specific localization of [3H]YM-09151-2 binding sites in the brain and spinal cord may prove useful for analyzing various dopaminergic functions in the central nervous system.

Animals↗

PubMed1994

Coexistence of oxytocin and NADPH-diaphorase in magnocellular neurons of the paraventricular and the supraoptic nuclei of the rat hypothalamus.

Nitric oxide (NO), which was firstly identified as an endothelium-derived relaxing factor, has recently been demonstrated to be a neurotransmitter in the central and peripheral nervous systems. In the hypothalamus, abundant nitric oxide synthase (NOS) immunoreactivity and its histochemical marker, NADPH-diaphorase activity, have been demonstrated in the hypothalamo-neurohypophyseal system. In the present study, we examined whether NOS is coexpressed with posterior pituitary hormones in the rat hypothalamus by combination of oxytocin and vasopressin immunofluorescence and NADPH-diaphorase histochemistry. Most oxytocin-immunoreactive neurons in the paraventricular and supraoptic nuclei expressed NADPH-diaphorase activity, but virtually no vasopressin-immunoreactive neurons contained NADPH-diaphorase activity. This suggests that oxytocin neurons are the main source of NO production in the hypothalamic-pituitary system.

Animals↗

PubMed1994

The number of noradrenergic and adrenergic neurons in the brain stem does not change with age in male Sprague-Dawley rats.

We examined whether or not the number of noradrenergic and adrenergic neurons changes with age, using peroxidase antiperoxidase (PAP) immunohistochemistry with specific antisera against tyrosine hydroxylase (TH) and phenylethanolamine-N-methyltransferase (PNMT). TH- and PNMT-immunoreactive neurons were counted in every noradrenergic and adrenergic neuron group of young (3-month-old) and old (24-month-old) rats. The differences in the counted number of TH- and PNMT-immunoreactive neurons did not reach statistical significance between the young and old rats.

Aging↗

PubMed1994

Biochemical and immunocytochemical changes induced by intrastriatal 6-hydroxydopamine injection in the rat nigrostriatal dopamine neuron system: evidence for cell death in the substantia nigra.

Biochemical and immunocytochemical changes after unilateral 6-hydroxydopamine (6-OHDA) injection into the striatum were investigated in the rat nigrostriatal dopamine (DA) neuron system. Four weeks after 6-OHDA injection into the striatum, concentrations of DA and its metabolites were specifically decreased in the substantia nigra (SN), as well as in the striatum, ipsilateral to the injection. Immunocytochemistry of tyrosine hydroxylase (TH) revealed a marked decrease in the number of TH-immunoreactive neuronal cell bodies in the SN ipsilateral to the injection; this effect appeared 2 weeks after the injection and remained even 10 months after the injection. Electron microscopic study of these periods demonstrated degenerative neurons in the SN pars compacta, suggesting that the degenerative changes persisted for a long time after a single injection of 6-OHDA into the striatum. The results showed that degeneration of the dopaminergic terminals in the striatum may lead to cell death of the parent cell bodies in the SN and suggest that the striatum may be the initial site in which the neurodegeneration occurs in Parkinson's disease.

Animals↗

PubMed1994

Catecholaminergic input to spinally projecting serotonin neurons in the rostral ventromedial medulla oblongata of the rat.

The midline of the rostral ventral medulla (RVM) is the portion in which many serotonin (5-HT) neurons of the nucleus raphe magnus and the rostral nucleus raphe pallidus are located and where dense catecholaminergic (CA) fibers are distributed. In this study, we investigated the connection between spinally projecting 5-HT neurons and CA fibers in the rat RVM by light and electron microscopic immunocytochemistry. First, light microscopic immunocytochemistry using a triple labeling method revealed that the 5-HT-immunoreactive (IR) neuron containing retrograde tracer from the cervical cord was intimately surrounded by tyrosine hydroxylase (TH)-IR fibers. Second, silver-gold intensified TH-IR axon terminals were found to make synaptic contacts with 5-HT-IR neuronal perikarya and dendrites by double labeling immunoelectron microscopy. These morphological findings suggest that spinally projecting 5-HT neurons, presumed to be involved in pain modulation or sympathetic autonomic control, are directly regulated by CA neurons at the level of the RVM.

Animals↗

PubMed1994

Neuropeptide participation in canine laryngeal sensory innervation. Immunohistochemistry and retrograde labeling.

We investigated the quantitative participation of calcitonin gene-related peptide (CGRP), substance P (SP), and leu-enkephalin (ENK) in canine laryngeal sensory innervation by immunohistochemistry in combination with retrograde labeling using the recently introduced retrograde tracer cholera toxin subunit B-conjugated gold (CTBG). In the nodose ganglion, neurons labeled from the internal branch of the superior laryngeal nerve with CTBG were investigated immunohistochemically by means of antisera against CGRP, SP, and ENK. The percentages of neurons immunoreactive to each neuropeptide were as follows: CGRP 81.5%, SP 24.5%, and ENK 7.0%. These results suggest that CGRP is the main sensory neurotransmitter in canine laryngeal sensory innervation.

Animals↗

PubMed1994

Immunocytochemical investigation of rat gamma-glutamyl transpeptidase in chemically-induced hepatocarcinogenesis using monoclonal antibody.

An immunocytochemical study using a monoclonal antibody showed the presence of gamma-glutamyl transpeptidase (gamma-GTP) in the bile duct epithelium of the normal adult rat liver, while a slight immunoreactivity for gamma-GTP could be observed on the membranes of bile canaliculi (the membranes of hepatocytes facing the lumen of bile canaliculi). In hepatocarcinogenesis induced by 3'-methyl-4-dimethylaminoazobenzene, no immunoreactivity was detected in alpha-fetoprotein-positive cholangiolar "oval" cells, though it was detected on the membranes of bile canaliculi. In livers with hyperplastic nodules, gamma-GTP immunoreactivity was observed in clusters, with two different staining patterns. In one pattern, gamma-GTP was present not only on the membranes of bile canaliculi, but also on the membranes facing the Disse's space or the lateral cell surface of hepatocytes. In the other pattern, gamma-GTP immunoreactivity was seen on the membranes of the dilated bile canaliculi. In livers with developing hepatocellular carcinomas, the immunoreactivity was present on the membranes of irregularly dilated bile canaliculi in malignant cells.

Animals↗

PubMed1994

Calcitonin gene-related peptide-like immunoreactive motoneurons innervating the canine inferior pharyngeal constrictor muscle.

The percentage of the calcitonin gene-related peptide-immunoreactive motoneurons (Mn) in the nucleus ambiguus (NA) innervating the canine inferior pharyngeal constrictor muscle was examined using the cholera toxin B subunit-gold (CTBG) as a retrograde tracer and by immunohistochemistry. Labeled neurons with CTBG (CTBG MNs) from the thyropharyngeal muscle (TP) were located in the dorsomedial division of the rostral part of the NA and the average percentage of neurons with CGRP immunoreactivity was 70.3%. CTBG MNs from the cricopharyngeal muscle (CP) were located in the dorsal division of the rostral part of the NA and the average percentage of neurons with CGRP immunoreactivity was 21.2%. This low percentage of CGRP immunoreactivity is noteworthy and supports the idea that the CP is a particular striated muscle in function and innervation manner.

Animals↗

PubMed1993

Cholinergic neurons contain Calbindin-D28k in the monkey medial septal nucleus and nucleus of the diagonal band: an immunocytochemical study.

The distribution patterns of choline acetyltransferase (CAT), as a marker for cholinergic neurons, and Calbindin-D28k (CaBP) immunoreactivities in the forebrain basal ganglia of the Japanese monkey Macaca fuscata were compared. Similar distribution patterns of CAT and CaBP immunoreactivities were found in the medial septal nucleus (MS) and the nucleus of the diagonal band of Broca (DBB). Double-labeling fluorescence immunocytochemistry revealed that most, but not all, cholinergic neurons were CaBP-immunoreactive in the MS and DBB. The results suggest that CaBP may play a role in the septohippocampal cholinergic neuron system of the monkey.

Animals↗

PubMed1993

Resistance of hypothalamic dopaminergic neurons to neonatal 6-hydroxydopamine toxicity.

We studied the effects of neonatal intracisternal administration of the 6-hydroxydopamine (6-OHDA) following desipramine pretreatment on dopaminergic (DA) neurons in the rat hypothalamus and substantia nigra by immunocytochemistry with an antiserum against tyrosine hydroxylase (TH). Neonatal intracisternal 6-OHDA injection induced almost complete loss of the TH-immunoreactivity in the substantia nigra and the caudate-putamen when examined at final (adult) stage. However, in this stage, no difference of TH-immunoreactivity was observed in hypothalamic DA neurons in the arcuate nucleus (A12), periventricular area (A14), zona incerta (A13), and posterior hypothalamic area (A11). In the initial (neonatal) stage after the 6-OHDA injection, nigral DA neurons started to degenerate in 12 h and were almost completely destructed in 96 h, but hypothalamic DA neurons did not show any degenerative change at any time examined. The route of the injection (cistern, third ventricle or lateral ventricle) of the toxin did not influence the distribution of damage. These data show that 6-OHDA is not equally toxic to all brain DA neurons in neonates, and that all hypothalamic DA neuronal groups resist the toxicity of 6-OHDA, despite their anatomical and functional differences.

Animals↗

PubMed1993

Differential expression of serotonin and [Met]enkephalin-Arg6-Gly7-Leu8 in neurons of the rat brain stem.

The hypothesis that serotonin (5-HT) and [Met]enkephalin-Arg6-Gly7-Leu8 (MEAGL) coexist in the rat brain stem raphe nuclei was tested by a technique combining histofluorescence with immunocytochemistry, after treatment with colchicine and nialamide. In midbrain and pons serotonergic cell groups (B5-B9), no coexistence of 5-HT and MEAGL was detected. In serotonergic cell groups of the medulla oblongata (B1-B3), only 0.3-1.5% of 5-HT-fluorescent cells were MEAGL-immunoreactive. These findings suggest that putative 5-HT and MEAGL are mostly expressed in different populations of neurons in the rat raphe nuclei.

Animals↗

PubMed1993

The direct retinal projection to VIP neuronal elements in the rat SCN.

The connection between optic nerve terminals and vasoactive intestinal peptide (VIP)-containing neurons in the rat suprachiasmatic nucleus (SCN) was investigated using double labeling immunocytochemistry. Cholera toxin B subunit (CT) was injected into the right eyeball, and coronal sections of the SCN were then processed for CT immunocytochemistry with silver-gold intensification and VIP immunocytochemistry consecutively with DAB staining alone. In the ventrolateral portion of the SCN, CT immunoreactive (CT-IR) optic nerve terminals were found to make synaptic contacts not only with VIP-like immunoreactive (VIP-LI) dendrites, but also with VIP-LI perikarya. CT-IR nerve endings were also found to make synaptic contacts with non-VIP immunoreactive neuronal dendrites.

3,3'-Diaminobenzidine↗