Ependym und Circumventriculäre Organe

Leonhardt, Von H.

doi:10.1007/978-3-642-81358-0_3

Cited by 112 publications

(119 citation statements)

References 1,698 publications

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“…, LEONHARDT, 1980. Later, however, the secretory material observed light microscopically on the ventricular surface of the paraventricular organ was found, ultrastructurally, to consist of tightly packed nerve terminals (VIGH , 1966;TAKEICHI, 1967;ROHLICH and VIGH, 1967).…”

Section: Discussionmentioning

confidence: 99%

The system of cerebrospinal fluid-contacting neurons.

Vigh-Teichmann

Vígh

1983

Arch. Histol. Jap., Arch. Histol. Jpn

128

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Section: Discussionmentioning

confidence: 99%

The system of cerebrospinal fluid-contacting neurons.

Vigh-Teichmann

Vígh

1983

Arch. Histol. Jap., Arch. Histol. Jpn

128

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“…After intracerebroven tricular application, on the other hand, VP was re ported to increase BBB permeability to water (Raichle and Grubb, 1978), an effect probably me diated by noradrenergic pathways (Raichle, 1981;Pardridge, 1983). Although the consequences of altered BBB per meability remain to be clarified, the evidence sug gests that changes in the permeability of the BBB can be triggered by peptides and may be physiolog ically important phenomena (Ermisch et a!., 1982 Peptides may reach neuronal elements in some circumventricular organs (van Houten and Posner, 1983), but there is no evidence of penetration to deeper layers of the brain (see Leonhardt, 1980;Krisch et aI. , 1983).…”

Section: Bbb Permeability Alterations By Peptidesmentioning

confidence: 99%

“…The surface area of the tight capillary endothelium amounts to >99% of the total brain capillary surface area (Crone, 1971). Al ternatively, in a few and mostly microscopic regions formed by cells derived from the ependymal matrix (Leonhardt, 1980) and belonging to the morpholog ically as well as functionally heterogeneous circum ventricular organs (Hofer, 1959;Leonhardt, 1980), endothelial cells are fenestrated and, typically, not connected by tight junctions [for review, see Leon hardt (1980)]. Therefore, in the circumventricular organs of mammals, including the choroid plexus, the vascular organ of the lamina terminalis, the subfornical organ, the pineal body, the area pos trema, the neurohypophysis, and the median emi nence but excluding the subcommissural organ, the capillary endothelial cell layer is leaky.…”

mentioning

confidence: 99%

“…Therefore, in the circumventricular organs of mammals, including the choroid plexus, the vascular organ of the lamina terminalis, the subfornical organ, the pineal body, the area pos trema, the neurohypophysis, and the median emi nence but excluding the subcommissural organ, the capillary endothelial cell layer is leaky. Although a BBB is absent from the circumventricular organs, however, their perivascular space with the phago cytic cells is separated from the extracellular space of the brain and from the CSF, respectively, by a sheath of cells connected by tight junctions (see Leonhardt, 1980;Krisch et aI., 1983).…”

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confidence: 99%

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Blood—Brain Barrier and Peptides

Ermisch

Rühle

Landgraf

et al. 1985

J Cereb Blood Flow Metab

183

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Summary: The brain is both the source and the recipient of peptide signals, The question is: Do endogenous, blood-borne peptide molecules influence brain function?Brain regions with the tight capillaries of the blood-brain barrier (BBB) extract low but measurable amounts of la beled peptide molecules from an intracarotid bolus injec tion, In the rat, the extraction fractions of f3-casomor phin-5, DesGlyNH2-arginine-vasopressin, arginine-vaso pressin, lysine-vasopressin, oxytocin, gonadoliberin, substance P, and f3-endorphin, studied in this laboratory, range from 0.5% (substance P) to 2.4% (arginine-vaso pressin). Extraction varies little among the 15 examined brain regions. As shown for arginine-vasopressin, the ex tracted peptides may be bound in part to specific binding sites located on the luminal membrane of the tight en dothelial cells. Tr ansport of peptide molecules across the BBB cannot be ruled out, but it is unlikely that endoge nous peptides pass the BBB in physiologically significant amounts. In contrast, in brain regions with leaky capil- BRAIN AND PEPTIDESNeurons process information. The process in cludes the release of chemical signals such as ace tylcholine, catecholamines, indolamines, amino acids, and peptides [for review, see Ganong (1982)]. There is evidence that numerous neuronal cell pop ulations produce and release peptides [for review, see Swaab (1982)J. Certain peptides including va sopressin (VP) and oxytocin (OT) trigger events in the brain itself as well as in the periphery of the body (Sterba et aI., 1981). Thus, the neuropeptides may serve in at least two lines of communication (Ermisch, 1980). First, they may trigger events within the brain when released into the synaptic cleft, or second, they may trigger events within the 350laries, e.g., selected circumventricular organs including the pineal gland, neurohypophysis, and choroid plexus, the peptide fraction extracted approaches that of water.Within the circumventricular organs, the peptide mole cules actually reach the cellular elements of the tissue.However, no studies definitively show that pep tides reach neurons in the deeper layers of the brain. On the other hand, blood-borne peptides influence the BBB per meability by altering the transport of essential sub stances. The effect may be mediated by specific peptide binding sites located at the luminal membrane of the en dothelium. It is possible that the effect of peptides on the BBB is necessary for proper brain function. There is some evidence that peptides, released centrally into the synaptic clefts as well as peripherally into the blood stream, support complex brain performances by both of these pathways.

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“…Nevertheless, several works point to the heterogeneity of the ependymal cells showing variability, e.g., in form, arrangement and the number of the cells in layers (Leonhardt 1980;Mitro & Palkovits 1981, Mathew 2008Del Bigio 2010;Mitro et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Method of labelling of individual ependymal areas according to periventricular structures of the rat lateral brain ventricles

Mitro

2014

Biologia

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Ependymal areas were studied in the lateral brain ventricles of the rat central nervous system and were labelled with a code. The presented suggestion using the coding for individual ependymal areas in rat ventricle may solve the significant problem in experimental studies, i.e. how to secure the mutual comparison of the same type of ependymal areas or ependymal cells. The periventricular structures represent a basic and stable part of brain nerve tissue and they are localized most closely to the studied part of the ventricle wall. For this quality they were chosen as reference nerve tissue for the labelling of the ependymal areas and they were used for the creation of the code. The code is composed from letters "Lv" (lateral ventricle) and "E" (ependymal area) followed by the abbreviation of the latin name of the periventricular structure, e.g., the corpus callosum abbreviation is "cc". The code of the ependymal area over the corpus callosum is thus "LvE-cc". The proposed labelling of the ependymal areas may offer several advantages, such as: (i) better characterization of ependymal areas in the future; (ii) preventing the interchange of different types of ependymal areas or ependymal cells; and (iii) avoiding a false interpretation in experiments.

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Ependym und Circumventriculäre Organe

Cited by 112 publications

References 1,698 publications

The system of cerebrospinal fluid-contacting neurons.

The system of cerebrospinal fluid-contacting neurons.

Blood—Brain Barrier and Peptides

Method of labelling of individual ependymal areas according to periventricular structures of the rat lateral brain ventricles

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