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At least 217 records · Page 12Linked to original sources
PubMed2004

Vestibulosympathetic reflex mediates the pressor response to hypergravity in conscious rats: contribution of the diencephalon.

To investigate the mechanism of arterial pressure (AP) regulation during hypergravity, the AP response to gravitational force was examined in conscious rats and the AP was found to increase, depending on the degree of gravity load induced by centrifugation. At 20 s after application of 2, 3, or 5 G, the AP increased by 9+/-2, 20+/-3, or 24+/-3 mm Hg, respectively. The AP increase during first 60 s was suppressed by vestibular lesion or pretreatment with hexamethonium, suggesting that the vestibular system and sympathetic nerve system be involved, respectively, in the afferent and efferent pathways. To further examine the central pathway of this response, Fos expression in the brain was examined after exposure to 5 G for 90 min. Intense Fos expression was seen in the medial vestibular nucleus, paraventricular hypothalamic nucleus, autonomic nuclei in the brain stem in intact rats, but not in rats with vestibular lesion. To examine the involvement of the diencephalic nuclei in this pressor response, AP was measured under hypergravity in rats with midcollicular transection. In these rats, the AP change was minimal at 2, 3, and 5 G, indicating that nuclei rostral to the transection level were involved in the pressor response. These results indicate that output from the vestibular system project to the diencephalon, and activation of diencephalic nuclei is indispensable to the pressor response via the sympathetic nerve system.

Analysis of Variance↗
PubMed2004

Distribution of ACTH immunoreactivity in the diencephalon and the brainstem of the dog.

The present work describes for the first time the anatomical distribution of adrenocorticotropic hormone (ACTH) in the diencephalon and the brainstem of the dog by means of the indirect immunoperoxidase technique. The distribution found in this species agrees well with the pattern found in other mammals and particularly confirms much of the findings reported in the cat. An exception to that concordance is the presence of ACTH perikarya in the nucleus of the solitary tract of the dog, a population that has been described in the rat but not in the cat, and in the ventral mesencephalon. This last population spread across the ventral tegmental area from the raphe to the cerebral peduncle and appeared to be a specific feature of the canine brain. On the other hand, we can not see ACTH fibers in the substantia nigra of the dog which could be a characteristic of the domestic carnivores, opposite to rodents, since these fibers appeared to be also lacking in the cat. Nevertheless, the widespread distribution of ACTH fibers in the brain of the dog included many other nuclei containing monoaminergic neurons which supported a possible role for ACTH in the regulation of these neurotransmitter systems.

Adrenocorticotropic Hormone↗
PubMed2001

The teleostean (zebrafish) dopaminergic system ascending to the subpallium (striatum) is located in the basal diencephalon (posterior tuberculum).

Tyrosine hydroxylase immunohistochemistry is used to demonstrate catecholaminergic neuronal populations in the fore- and midbrain of adult zebrafish (Danio rerio). While no catecholaminergic neurons are found in the midbrain, various immunoreactive populations were found in the diencephalon (hypothalamus, posterior tuberculum, ventral thalamus, pretectum) and telencephalon (preoptic region, subpallium, olfactory bulb). The posterior tubercular catecholaminergic cells include three cytological types (small round, large pear-shaped, and bipolar liquor-contacting cells). Furthermore, the retrograde neuronal tracers DiI or biocytin were applied to demonstrate ascending projections to the basal telencephalon (incl. the striatum). A double-label approach was used - together with tyrosine hydroxylase immunohistochemistry - in order to visualize neurons positive for tyrosine hydroxylase and a retrograde tracer. Double-labeled cells were identified in two locations in the posterior tuberculum (i.e, small round neurons in the periventricular nucleus of the posterior tuberculum and large pear-shaped cells adjacent to it). They are interpreted as the teleostean dopaminergic system ascending to the striatum, since previous work [16] established that no noradrenergic neurons exist in the forebrain of the adult zebrafish.

Animals↗
PubMed1997

Regional distribution of neural cell adhesion molecule immunoreactivity in the adult rat telencephalon and diencephalon. Partial colocalization with heparan sulfate proteoglycan immunoreactivity.

In the present paper immunocytochemical analysis at the fluorescence microscopical level has been performed of neural cell adhesion. molecule (NCAM) immunoreactivity in the adult rat tel- and diencephalon in order to further substantiate the highly selective neuronal localization of NCAM immunoreactivity, using an affinity purified rabbit antiserum recognizing homologous NCAM proteins from rat brain. Also, double immunolabelling experiments were performed with monoclonal antibodies specific for heparan sulfate related epitopes or gamma-aminobutyric acid (GABA) to establish in which cell populations a colocalization existed with immunoreactive heparan sulfate proteoglycans of GABA. Within the neocortex NCAM immunoreactivity was exclusively localized to the area of the cell membrane of soma and proximal dendrites of subsets of large pyramidal nerve cells of the layer 5 of the frontoparietal cortex. Within the dorsal hippocampus, the NCAM immunoreactivity was exclusively located to the cell surface area of the pyramidal cell bodies of area CA2. Two colour immunofluorescence procedures demonstrated a colocalization of NCAM and 3G10 but not 10E4 immunoreactivities in the cell surface area of many of the NCAM-positive nerve cell bodies of these two regions. Within the thalamus, strong NCAM immunoreactivity was exclusively demonstrated at all rostrocaudal levels of the reticular thalamic nucleus. The horizontal band of NCAM immunoreactivity was not continuous, but split up into patches of NCAM immunoreactivity within groups of nerve cell bodies. When analysing the number of cells per unitary square in the rostrocaudal direction, a significant increase of positive cells was found in the rostral and middle thirds versus the caudal third of the reticular thalamic nucleus. Many of the cell bodies with NCAM immunoreactivity in their cell surface are showed cytoplasmic GABA immunoreactivity. In the three regions shown to contain NCAM immunoreactivity, proteins of the NCAM type may play a special role for the maintenance of the synaptic structure. The findings also suggest that the sulfated proteoglycans and NCAM can interact in the regulation of cell-cell interaction via adhesion. In the reticular thalamic nucleus NCAM molecules may be part of a set of cell-adhesion molecules involved in a structural organization of the nucleus, which allows it to play a key role in relating cortical maps to thalamic maps.

Animals↗
PubMed2003

Localization of the neuronal form of nitric oxide synthase (bNOS) in the diencephalon and pituitary gland of the catfish, Synodontis multipunctatus: an immunocytochemical study.

The distribution of the neuronal form of nitric oxide synthase (bNOS) was investigated in the brain and pituitary gland of the catfish, Synodontis multipunctatus. Immunoreactive neurons were found mainly in the nucleus praeopticus periventricularis, the parvocellular and supraoptic subdivisions of the nucleus praeopticus, the nucleus recessus lateralis and the nucleus recessus posterioris. In addition, some scattered bNOS labeled somata were noted in the dorsal hypothalamic area. A few positive cells in the adenohypophysis and some reactive fibers in the pituitary stalk were also seen. Our results are compatible with the notion that the cells expressing bNOS in the diencephalon and hypophysis are involved in the control of hormone regulation. Moreover, the presence of bNOS positive cells in the rostral pars distalis of the pituitary gland supports a role of nitric oxide in osmoregulation.

Animals↗
PubMed1997

Postnatal expression of melanocortin-3 receptor in rat diencephalon and mesencephalon.

In situ hybridization was applied to examine the postnatal expression of melanocortin-3 (MC-3) receptor mRNA in the rat brain. Very weak and limited signals were seen in the hypothalamus on postnatal day 0 (P0) and in the dorsal lateral thalamus on P4. A marked increase was noted in several regions of the diencephalon and mesencephalon on P7. The highest levels were reached on P21, which was the time when an adult-like pattern was established. On P21, intense signals were seen in the ventromedial nucleus and the arcuate nucleus of the tuberal hypothalamus, the habenular nucleus of the epithalamus and the ventral tegmental area. [125I] Nle4, D-Phe7-alpha-MSH showed overlapping, but wider labelling of melanocortin receptors, that followed a similar developmental course. alpha-MSH-like immunoreactivity was seen widely in the forebrain and midbrain from P14. In contrast to the staining of alpha-MSH in neurons and their process, gamma 2-MSH-like immunoreactivity was detected strongly in the blood vessels. The neuronal localization of MC-3 receptor mRNA suggests that this receptor may mediate the neurotropic actions of melanocortin peptides in the developing brain.

Animals↗
PubMed2000

Overexpression of mSim2 gene in the zona limitans of the diencephalon of segmental trisomy 16 Ts1Cje fetuses, a mouse model for trisomy 21: a novel whole-mount based RNA hybridization study.

Trisomy 21 (Down syndrome) is the most common chromosomal abnormality associated with mental retardation in humans. Sim2, a human homologue of Drosophila sim gene, which acts as a master regulator of the early development of the fly central nervous system midline, is located on chromosome 21, in the Down syndrome critical region, and might therefore be involved in the pathogenesis of some of the morphological features and brain anomalies observed in Down syndrome. We report here the detailed expression pattern of murine mSim2 gene in Ts1Cje mice fetuses, a segmental trisomy 16 mouse model for trisomy 21, and its overexpression in the zona limitans of the diencephalon using a new quantitative method based on the whole-mount RNA hybridization technique.

Animals↗
PubMed1997

Fos-like immunoreactivity in the caudal diencephalon and brainstem following lateral hypothalamic self-stimulation.

Fos immunohistochemistry was used to stain neurons in the caudal diencephalon, midbrain and hindbrain driven by rewarding stimulation of the lateral hypothalamus (LH). Increases in Fos-like immunoreactivity were most pronounced ipsilateral to the site of stimulation and tended to be confined within discrete structures such as the posterior LH, arcuate nucleus, ventral tegmental area (VTA), central gray, dorsal raphé, pedunculopontine area (PPTg), parabrachial nucleus, and locus coeruleus. At least two of these structures, the VTA and PPTg, have been implicated in medial forebrain bundle self-stimulation.

Animals↗
PubMed1999

Catecholaminergic neurons in the diencephalon and basal ganglia of SIDS.

The catecholaminergic systems of sudden infant death syndrome victims were examined in the diencephalon and basal ganglia, in addition to the midbrain, pons, and medulla oblongata, using the immuno-histochemical method involving tyrosine hydroxylase. A significant decrease in tyrosine hydroxylase immunoreactivity was demonstrated in the basal ganglia of sudden infant death syndrome victims between 2 to 12 months of age compared with age-matched control subjects. This change in the basal ganglia may be a secondary finding induced by chronic hypoxia or repeated ischemia in sudden infant death syndrome but suggests impairment of the development of the neuronal connection from the brainstem to the upper cardiorespiratory control in sudden infant death syndrome.

Basal Ganglia↗
PubMed1995

Notes on the organization of the rostral diencephalon of the atherinomorph swordtail-fish Xiphophorus helleri.

By using conventional histological methods, the nuclear organization of the rostral diencephalon of the swordtail-fish, Xiphophorus helleri (Poecilidae, Atherinomorpha, Teleostei) was analyzed and compared with those from other teleost species. The subdivisions of the entopeduncular region, especially in their relative position and cytoarchitectonic structure, reveal clear differences between the various teleost orders. A new nucleus, the lateral entopeduncular nuclear area (leNA), found within this region, is described.

Animals↗
PubMed1993

Segmental organization of embryonic diencephalon.

The diencephalon is a complex integration centre and intricate relay station of the vertebrate brain. Its development involves the generation of great cellular diversity and neuronal specificity. We report here that it becomes organized in steps, through a stereotyped sequence of neuromeric subdivisions. Diencephalic neuromeres define four cellular domains (D1-D4) that can be followed throughout development, each unit contributing to a well defined part of the adult structural pattern. We propose that the segmental identity of each diencephalic unit is specified by a unique combination of genes, maintained by polyclonal cell lineage restrictions. A comparison of vertebrate and arthropod development suggests that the basic principles that control anterior axial patterning and set up neuronal specificity in the embryonic central nervous system are highly conserved in evolution.

Acetylcholinesterase↗
PubMed1994

Spatiotemporal expression patterns of chicken ovalbumin upstream promoter-transcription factors in the developing mouse central nervous system: evidence for a role in segmental patterning of the diencephalon.

Chicken ovalbumin upstream promoter-transcription factor (COUP-TF) genes encode transcription factors belonging to the orphan subfamily of the steroid/thyroid hormone receptor superfamily. Two COUP-TF counterparts have been cloned from mouse. In an attempt to study the function of these genes in the developing central nervous system (CNS), the spatiotemporal expression patterns of the two mouse genes have been examined by in situ hybridization. Both genes are widely expressed in the developing CNS, with patterns that are overlapping yet distinct from each other. The differential expression of murine COUP-TFI and -II in the diencephalon is striking in that high levels of expression from each gene are confined to specific segmental compartments--the neuromeres. Our results suggest that murine COUP-TFs may play important roles in the development and differentiation of the CNS, including the specification of diencephalic neuromeres.

Amino Acid Sequence↗
PubMed1975

Somatosensory cerebral evoked potentials after vascular lesions of the brain-stem and diencephalon.

Clinical and electrophysiological observations are described in 7 patients with clinically well-identified vascular lesions of the brain-stem or diencephalon. In the patients of Group A with a thalamic syndrome, the somatosensory cerebral evoked potentials had a reduced voltage and increased latency on the affected side. No significant anomalies were recorded in the patients of Group B with a Wallenberg or Weber syndrome. In patients of group C with a locked-in syndrome, the cerebral evoked potentials presented marked bilateral anomalies which provided interesting data about the extension of the pontine vascular lesions into the tegmentum. The pathophysiological mechanisms involved in the changes of average cerebral evoked potentials and in the slowing of corticipetal conduction are discussed.

Adult↗
PubMed1995

Unusual brain nucleus in the diencephalon of a perciform (nototheniid) fish from Antarctica.

This cytoarchitectonic analysis on the rostral diencephalon of antarctic perciform fishes confirms the previously established perciform diencephalic body plan. However, it resulted in the detection of an additional, large and conspicuous brain nucleus (unusual nucleus, UN) in the antarctic nototheniid Pleuragramma antarcticum. This nucleus has not been seen before in any other perciform. The UN is probably homologous to a visually related nucleus (named nucleus rostrolateralis and lateral entopeduncular nuclear area, respectively), that has so far only been found in two most primitive (osteoglosso-form) and one most highly derived (atherinoform) species of teleost. Our present results indicate that this brain region, which belongs to the ancient diencephalic organization of ray-finned fishes, is expressed in the brains of fishes due to their particular requirements regarding life styles rather than due to their phylogenetical relationships.

Animals↗
PubMed1992

Sodium dependence of [3H]paroxetine binding and 5-[3H]hydroxytryptamine uptake in rat diencephalon.

The sodium dependence of binding of [3H]-paroxetine, a selective serotonin uptake inhibitor, to the serotonin transporter in rat diencephalon was studied in both brain membranes and tissue sections and compared with that of 5-[3H]hydroxytryptamine ([3H]5-HT) uptake by synaptosomes from the same region. Binding of [3H]-paroxetine in both the membranes and sections displayed clear sodium dependence until a plateau occurring at 60 nM NaCl, the EC50 for sodium being 8 and 25 mM, respectively. The affinity (1/KD) of [3H]paroxetine binding was a simple hyperbolic function of sodium concentration. In contrast, the density of [3H]paroxetine sites was not affected by external Na+ concentration. The uptake of [3H]5-HT showed a similar pattern of sodium dependence with an EC50 for Na+ of 25 mM. Both the affinity (1/Km) and the rate (Vmax) of [3H]5-HT uptake were dependent on external [Na+] with sodium-dependence curves fitting a rectangular hyperbola. The kinetic analysis of results indicates that one sodium ion is required for the binding of [3H]paroxetine as well as for the binding and translocation of each [3H]5-HT molecule. The results concur with a single-site model of the sodium-dependent serotonin transporter with common or overlapping domains for 5-HT and 5-HT uptake inhibitors.

Animals↗
PubMed1998

Localization and quantification of melatonin receptors in the diencephalon and posterior telencephalon of the sheep brain.

In an attempt to better understand the mechanisms by which melatonin controls neuroendocrine activity, we tried to define with accuracy the brain areas where the density of melatonin receptors is the highest in sheep and to establish their characteristics. The specific labelling of 125I-melatonin was first revealed by autoradiography on brain sections of the posterior telencephalon and diencephalon in three ewes. The extent and position of the five structures where the binding was found to be the highest (i.e., the pars verticalis and pars horizontalis of the nucleus tractus diagonalis, the septal area, the bed nucleus of the stria terminalis, and the ventromedial hypothalamic area) were then accurately defined by image analysis. In comparison to the landmarks given by image analysis, photographs of coronal sections of another ewe permitted the accurate definition of the limits of the structures to be punched in a second step. In six ewes, each of the five structures previously identified were punched from frozen coronal sections and binding of 125I-melatonin to membrane preparations was studied individually by Scatchard analysis. The correlation coefficient between the B/F ratio and binding (B) was in the range of 0.96-0.98, indicating that a precise quantification was possible in these different structures. The Bmax was the highest in the bed nucleus of the stria terminalis, the septal area, and the ventromedial hypothalamic area (1.38, 1.25, and 0.95 fmol/mg protein, respectively). All Kd values were less than 10 pM and the Hill coefficient was close to 1, indicating the presence of a single class of receptor to 125I-melatonin. These results indicate the reliability of a method used to measure with accuracy low concentrations of melatonin receptors in brain structures. In addition, the ventromedial hypothalamic area was found to be rich in melatonin receptors. This region is known to be involved in the central gonadotrope control in sheep.

Animals↗
PubMed1988

Distribution of nicotinic cholinergic receptors in the rat tel- and diencephalon: a quantitative receptor autoradiographical study using [3H]-acetylcholine, [alpha-125I]bungarotoxin and [3H]nicotine.

The topographical distribution of [alpha-125I]bungarotoxin [125I]BTX, [3H]nicotine ([3H]Nic), [3H]acetylcholine ([3H]ACh) (in the presence of atropine) binding in rat tel- and diencephalon was investigated using a quantitative receptor autoradiographical technique. With the [3H]ACh and [3H]Nic radioligands, a strong labelling was observed in various thalamic nuclei, including the medial habenula, a moderate labelling in different areas of the cortex cerebri, the nucleus caudatus putamen, the nucleus accumbens and tuberculum olfactorium and a uniform weak labelling in the hypothalamus. When the binding data for [3H]Nic were plotted against binding data for [3H]ACh in various brain nuclei, a significant correlation was obtained. Considering [125I]BTX, the strongest labelling was observed in the lateral mammillary nucleus and the hilus gyrus dentatus of the hippocampal formation. A weak labelling occurred in areas such as the nucleus causatus putamen, the thalamus and the cerebral cortex. No significant correlation was therefore obtained between the degree of [125I]BTX binding in various brain nuclei and the degree of binding observed with [3H]Nic or [3H]ACh. The present results underline the view that the high-affinity [3H]Nic and [3H]ACh binding sites label the same cholinergic nicotinic receptor binding site, while [125I]BTX labels another subpopulation of nicotinic cholinergic receptors, predominantly found in discrete areas of the hypothalamus and the limbic cortex.

Acetylcholine↗