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At least 19 recordsLinked to original sources
PubMed1976

Amino acid transport in isolated neurons and glia.

Our efforts have been directed towards characterizing amino acid uptake, metabolism and release in bulk-isolated glia and neuronal perikarya studied in parallel with nerve-endings, especially as it concerns the transmitter amino acids and the participation of glia in the clearing of the synpatic space during impulse conduction. A possible neuromodulator role for the glia at the synapse is also suggested by K+-stimulated release. Our most definitive conclusions have been based so far on studies with GABA, although we are also beginning to accumulate data for glutamate related to glutamate-glutamine compartmentation. Glia preferentially accumulate potassium and amino acids compared to neuronal perikarya, have higher Na+/K+-ATPase activity, possess high-affinity, sodium-dependent uptake systems for GABA and glutamate similar to the ones in synaptosomes, and release amino acid in response to a potassium pulse by a calcium-independent process. Low neuronal uptake could be due to loss of dendrites. Unidirectional GABA-flux from the synaptosomal to glial compartment is supported by high GAD in nerve endings compared to high GABA-T in glia. Glutamine may be a transmitter glutamate-precursor in nerve-endings since glutaminase activity is high in nerve-endings, but low in glia where glutamine is presumably made. Glutamine uptake in both glia and synaptosomes obeys low-affinity kinetics in contrast to glutamate, consistent with the inability of glutamine to excite the neuronal membrane. The studies with GABA, which are considerably more extensive, are supported by related work using glia in tissue-culture and autoradiography. There appears to be a suggested difference in the behavior of amines which were poorly taken up by the glial system. Glia, synaptosomes and neuronal perikarya, in general behaved similarly with respect to requirements for uptake and release, except in the case of Ca++, which exerted opposite effects on glial and synaptosomal uptake of GABA. We believe that work along these lines tends to firmly establish a direct role for glial cells as modulators of neuronal excitability and represents a convergence between transmitter amino acid neuropharmacology and cellular biochemistry. This not only deepens and enlarges the vocabulary of synaptic biochemistry but also undoubtedly will have major clinical applications in the fields of epilepsy and behavior.

Adenosine Triphosphatases↗
PubMed1979

Autoradiographic studies on the incorporation of tritiated uridine, leucine and methionine into Gomori-positive glia of rat hypothalamus.

The relative level of metabolic activity in Gomori-positive (Gp) glia was estimated by comparing the incorporation rates of 3H-uridine, 3H-leucine and 3H-methionine into the nuclear macromolecules of the glia, neurons, ependyma and subcommissural organ (SCO). The uptake of 3H-uridine by Gp glia was somewhat lower than that by neurons and SCO but higher than that by ependyma. The incorporation of 3H-leucine was about the same in all studied types of cells, except for a lower uptake by ependyma. The rate of 3H-methionine incorporation into Gp glia and SCO was higher than that into neurons and ependyma. The neuron: Gp glia ratios obtained in the present study (0.9--1.4) are more or less within the range of the neuron: cerebral glia ratios reported by others for newly synthesized molecules of RNA and proteins. The results suggest that Gp glia have a relatively high metabolic activity as compared to that in neurons and perhaps SCO.

Animals↗
PubMed1979

Intracellular marking with lucifer yellow CH and horseradish peroxidase of cells electrophysiologically characterized as glia in the cerebral cortex of the cat.

Intracellular microelectrodes filled with either Lucifer Yellow CH, a highly florescent dye, or horseradish peroxidase (HRP) were used to electrophysiologically characterize and mark cells in the cerebral cortex of cat. Fifty-eight cells, characterized electrophysiologically as glia, were marked with Lucifer Yellow CH. All were identified as protoplasmic astrocytes, and included cells in the glia limitans of the molecular layer. An additional 54 cells, similarly characterized as glia, were labeled with HRP. The results were the same; only protoplasmic astrocytes were labeled. The "staining quality" of the glia labeled with HRP was superior to that of cells injected with Lucifer Yellow; greater lengths of individual processes were revealed, and they could often be followed to blood vessels where they ended on the walls of vessels with expanded perivascular end-feet. The observations indicate that the many previously reported studies on presumed glial cells in the cat cerebral cortex have characterized the behavior of protoplasmic astrocytes. Neurons were also marked during these experiments. The "staining" quality of the Lucifer Yellow filled neurons was excellent; dendritic spines, axons, and axon collaterals were clearly visible. These fine neuronal details were not as well revealed after HRP labeling. High resting membrane potentials (RMP's) were not a prerequisite for obtaining well-marked neurons (mean RMP of Lucifer Yellow filled neurons was -33.6 mV; mean RMP of HRP filled neurons was 42.3 mV). In contrast, the mean RMPs of Lucifer Yellow and HRP marked glia was -68 Mv and -75 mV respectively, and the quality of "staining" appeared to be more closely related to the RMP.

Animals↗
PubMed1978

The fine structure of growing and non-growing whole glia cell preparations.

Human glia cells become blocked in G1 if starved of serum. The characteristics of the GI blocked state are flattening on the substrate, and absence of cell translocation, ruffling and macropinocytosis. Re-entry into the cell cycle, as a result of growth factor stimulation, is accompained and even preceded by the return of this cellular locomotion. We have studied the fine structure of intact human glia cells and ultrathin sections of these cells when proliferating normally in vitro, when starved of serum and during their return to the cell cycle following stimulation with mEGF (mouse epidermal growth factor). Particular attention was paid to morphologically definable components of the cellular musculoskeletal system. Proliferating interphase glia generally had a leading lamella containing few organelles and oriented bundles of 7 nm microfilaments with structureless lamellipodia at their tips, which often formed ruffles. The perinuclear area was thick and contained many cell organelles, including mitochondria and secondary lysosomes. Glia starved of serum were thinly spread; their peripheral cytoplasm was filled with a diffuse mat of microfilaments, they had no structureless lamellipodia and their perinuclear areas, although thinner, contained cell organelles in equal amounts and of similar type of those found in proliferating cells. On EGF stimulation, after approximately 2 hours the perinuclear area of the cells thickened, and structureless lamellipodia subsequently appeared at the tips of the leading lamellae, forming ruffles. The cells finally began to translocate, the process being accompained by the reorientation and packing of the microfilaments into bundles. As the kinetics of EGF binding and break down by glia cells are similar to those described for fibroblasts, the findings do not support the concept of EGF receptor interactions inducing ultrastructurally demonstrable microfilament or other musculoskeletal structural changes in the cell. They do, however, define the differing cellular morphologies of motile and immobile structures.

Cell Division↗
PubMed1975

Luxol Fast Blue MBSN-Levafix Red Violet E-2BL. A combined stain for myelin sheaths and glia fibers.

During investigations of reactive dyes, Levafix Red Violet E-2BL was found suitable for staining of glia fibers. Experiments were carried out on 37% formaldehyde-fixed human autopsy material. Paraffin sections were treated with Luxol Fast Blue MBSN as usual, differentiated until glia fibers were decolorized, and counter-stained in a 0.25% solution of Levafix Red Violet E-2BL in 0.25% acetic acid. Myelin sheaths were colored blue. Gila fibers, smooth muscle cells, and nuclei were stained red violet. Axons and connective tissue remained unstained; occasionally, coarse bundles of collagen showed patchy coloration. Polarization microscopic studies proved that Levafix Red Violet E-2BL is bound to well-oriented fibrous proteins in glia fibers. The similar staining and polarization microscopic properties of glia fibers and smooth muscle support previous findings that glia fibers contain a myosin-like protein.

Brain↗
PubMed1975

[Ultrastructural reaction of the multipotential glia in the cerebellum of the rat after treatment with 6-aminonicotinamide].

6-Aminonicotinamide (6-AN), an antimetabolite of nicotinamide, damages the astrocytes and oligodendrocytes through a blockade of the pentose phosphate pathway. Both types of glia cells become hydropic. A third type of glia cell, described by VAUGHN and PETERS, the multipotential glia, is affected to a lesser extent. These cells phagocytize and form pseudopodia after treatment with 6-AN. Thus the multipotential glia cells are 'marked' by the action of 6-AN, since they are obviously less dependent on the pentose phosphate pathway in the carbohydrate metabolism.

6-Aminonicotinamide↗
PubMed1978

Metabolic rates and intercellular transfer of molecules in cultures of human glia and glioma cells.

Metabolic rates and intercellular transfer of metabolites were studied in human glia and glioma culture cells via topographic scan of NAD(P)H fluorescence by multichannel microfluorometry in conjunction with microinjection of glucose-6-P + allosteric activators. Metabolic rates evaluated from NAD(P) in equilibrium NAD(P)H transients and the required substrate levels were 3--4 times lower in glioma cells as compared to glia cells. Both glia and glioma cells showed variability in the occurrence of intercellular metabolite transfer, detectable via observation of a transient in a neighbour of the cell injected with substrate. On this basis "multicellular integrated states" can be defined in clusters of glioma and glia cells interconnected by cell-to-cell contact and a mesh-like network of intercellular processes. Such multicellular steady states and the associated metabolic rates or their impairment can be used in turn to classify different culture lines in reference to cell physiology and pathology.

Adenosine Diphosphate↗
PubMedDate not supplied

A quantitative histological study of changes in neurons and glia in the Gunn rat brain.

The rostral part of the anterior limb of the anterior commissure (RAL) and the indusium griseum of the brains of Gunn rats and Wistar rats were examined quantitatively to assess the effects of hyperbilirubinaemia on the developing nervous system. The number of glia in the RAL was significantly less in Gunn rats than in the Wistar rats. The number of glia in the indusium griseum was similar in both groups but the Gunn rats showed a decrease of about 20% in the number of neutrons in this region. Myelination appeared to be unaffected and apart from an apparent increase in the number of dense bodies in astrocytes and oligodendrocytes there were no obvious morphological changes in either glia or neurons.

Animals↗
PubMed1979

The fine structure of growing human glia and glioma cells. Whole cell preparations.

Three lines of normal human glia cells and eight established lines of malignant glioma cells have been studied in the electron microscope (E.M.), using preparations of critical-point dried whole cells, sparsely grown on formvar-coated, E. M., gold grids. The malignant cell lines showed a very varied morphology, almost every line having its peculiarities as compared to the essentially identical normal glia lines. The major differences noted concerned the form of the leading lamellae, number of microspikes and the distribution of organelles such as secondary lysosomes and mitochondria. No single consistent finding made it possible to differentiate the glioma cells as a group from the glia cells in sparse cultures. The findings of this study show some of the individual glioma cell lines to have characteristic cell-surface structures. They were found to be identical with the findings in previous SEM studies, suggesting the peculiarities of the individual malignant glioma lines to be stable and retained, despite continual passage.

Cell Division↗
PubMed1975

[Quantitative determination of glia-specific proteins in the cerebrospinal fluid of patients with MS (author's transl)].

150 cerebrospinal fluids from MS patients (85 cases) and patients with different neurological diseases (65 cases) were investigated for their glia-specific content. The demonstration was made quantitatively by means of modified passive hemagglutination tests. The brain-specific glycoprotein was examined for its possible endogenous antigen and/or antibody properties in the cerebrospinal fluid (csf). It could only be demonstrated in the CSF as antigen. CSF with a quantitatively detectable glia-specific protein content- recognizable by a significant increase in titer - were set in relation to other CSF parameters such as cell count, total protein and globulin ratio, and investigated for possible relationships to the clinical syndromes mentioned and their development. A firm correlation was found between the glia-specific protein content and the total protein content of the CSF with retained equivalence.

Antigens↗
PubMed1978

Radial glia in the human fetal cerebrum: a combined Golgi, immunofluorescent and electron microscopic study.

Golgi techniques, immunofluorescence for glial fibrillary acidic (GFA) protein, and electron microscopy (EM) were used to determine the nature of radial glia in the cerebrum of human fetuses ranging from 7 to 20 weeks of ovulation age. Successful Golgi impregnation of radial fibers was achieved in fetuses 12 weeks of age and older. These fibers spanned the entire thickness of the hemisphere. At the pial surface many of them branched and terminated in pyramidal end feet expansions. Indirect immunofluorescent preparations utilizing antiserum to GFA protein, a protein specific for astrocytes, demonstrated numerous radially oriented nearly parallel fluorescent fibres between the ventricular zone and pia mater. GFA protein-positive fibers were demonstrated in all fetal specimens examined with this technique (10 weeks of age and older). Along the outer border of the marginal zone they formed a horizontal GFA protein-containing subpial membrane. By EM there were numerous linear electron lucent astrocytic processes containing 8-9 nm filaments and occasional glycogen granules at all levels of the cerebrum. They were interspersed among smaller and darker neuronal processes containing 20-25 nm neurotubules, and were demonstrable at all fetal ages between 7 and 18 weeks. They formed pericapillary investments and subpial terminal expansions closely abutting basal lamina of pia mater in every specimen examined. On the basis of these combined analyses, we conclude that radial glial fibers in early human fetal cerebrum represent processes of immature astrocytes. Although subsequently undergoing further maturation, radial glia already possess fundamental immunocytochemical and morphological characteristics indicative of astrocytic differentiation. A significant implication of our findings is that the development of astrocytes in the human fetal brain occurs much earlier than formerly believed.

Astrocytes↗
PubMed1978

Identification of Gomori-positive glia in autoradiographs.

Unstained Gomori or paraldehyde fuchsin or chrome-haematoxylin-alum positive granules in the perikaria of so-called Gomori-positive glia of the periventricular zone of the rat hypothalamus, fixed with Bouin's or Carnoy's fluids, have been found to produce a positive chemographic (blackening) effect on autoradiographic emulsion. Similar action was produced by some granules in ependymal cells localized in the ventral part of the third ventricle between optical chiasma and median eminence. It is suggested that this positive chemographic effect can be employed for the identification and characterization of Gomori-positive glia in autoradiographic studies.

Animals↗
PubMed1976

Neurotransmitter regulation of adenosine 3',5'-monophosphate in clonal nerve, glia, and muscle cell lines.

Norepinephrine increases the intracellular level of adenosine 3',5'-monophosphate (cyclic AMP) in clonal cell lines of nerve, glia, smooth muscel, and skeletal muscle. The largest response is in skeletal muscle, where the cyclic nucleotide concentration is elevated more than 500-fold. Glia and muscle cells, but not nerve cells, respond to dopamine with increased cyclic AMP accumulation. This response appears to be mediated through a beta-adrenoreceptor.

Cell Line↗
PubMed1979

[Prolongation of the mitotic life span of diploid human glia cells in a quantitative cell culture system by centrophenoxine (author's transl)].

The accumulation of lipofuscin in postmitotic and reversible postmitotic cells of animals and man is an age correlated process. The mechanism of the lipofuscin accumulation and the function of lipofuscin in the aging cell is not fully understood. The accumulation of lipofuscin in vivo and in vitro can be slowed down by the action of centrophenoxine (Helfergin). Diploid cells are the only reversible postmitotic cells of man that have a genetically determined limited cell division capacity and accumulate lipofuscin in the process of the cellular aging in a quantitative cell culture system in vitro. The treatment of diploid human glia cells with centrophenoxine results in increasing the cell division capacity by 30--40% in vitro. The data demonstrate that the centrophenoxine induced inhibition of lipofuscin accumulation has a positive influence on the cell metabolism and the mitotic division capacity and causes a delay of the cellular aging of the human glia cells in vitro.

Cells, Cultured↗
PubMed2026

Transient YAP activation uncovers the neurogenic potential of proliferative mammalian Müller glia.

The Hippo pathway effector YAP promotes spontaneous proliferation of Müller glia (MG), suggesting that bypassing Hippo signaling and activating YAP could enhance retinal regeneration. However, whether proliferative adult MGs retain meaningful neurogenic competence remains unclear. Here, using viral delivery of a Hippo-resistant YAP variant to wild-type adult MGs, we achieved transient YAP activation in adult MGs, inducing proliferation followed by cell-cycle withdrawal and differentiation. Intersectional genetic lineage tracing and EdU labeling, combined with transcriptomic analyses, revealed that YAP-activated MGs predominantly regenerate MGs, whereas only a subset gives rise to bipolar cell-like neurons. These results indicate that proliferative MGs acquire a state resembling that of late-stage retinal progenitors, with limited neurogenic lineage potential. We conclude that YAP-activated cell-cycle reentry inefficiently reprograms adult MGs toward photoreceptor or ganglion cell fates. These findings define the limited competence of proliferative adult MGs to contribute to neurogenic fates and provide a rigorous framework for assessing in vivo glial reprogramming strategies.

AAV↗
PubMed1979

Autoradiographic studies on the cellular localization of GABA and beta-alanine uptake by neurones and glia in tissue culture.

Nervous tissue cultures have proved to be an excellent tool for investigating the cellular localization of the uptake of transmitter substances using autoradiography. The uptake of [3H]GABA and [3H]beta-alanine was studied in cultures of cerebellum, brain stem, spinal cord and dorsal root ganglia (DRG) of the rat. In cultures of brain stem and spinal cord, [3H]GABA was taken up by a great number of neurones and by almost all glial cells, suggesting that glial elements might also be involved in the inactivation of this amino acid. In cerebellar cultures, [3H]GABA was accumulated by many interneurones, by Purkinje cells and by a great number of glial cells. The finding that cultured Purkinje cells accumulated [3H]GABA contrasts with observations made in the cerebellum in vivo or in slices where no labelling of Purkinje cells could be demonstrated. Since GABA is taken up to a great extent by Bergman glia which tightly surround Purkinje cells in vivo, it has been suggested that the barrier formed by these glial cells prevents the uptake of the amino acid into Purkinje cells. In cultured cerebellum this glial barrier might be disrupted or absent and therefore Purkinje cells are able to accumulate [3H]GABA. A similar glial barrier preventing the uptake of [3H]GABA might also exist in DRG, where neurones that were completely surrounded by satellite glial cells did not take up the amino acid, whereas isolated neurones that were deprived of their glial envelopments became intensely labelled. After incubation with [3H]beta-alanine, it was observed that only glial cells were labelled in cerebellar and DRG cultures, whereas in spinal cord and brain stem both neurones and glial cells took up the amino acid providing further evidence that beta-alanine might act as a transmitter substance in these two regions.

Alanine↗
PubMed1978

Glia-specific antigen in the intracranial tumors. Immunofluorescence study.

26 gliomas and 14 non-glial tumors were examined for the presence of nervous system specific antigen (CGSA) to assess the antigenic properties of neoplastic tissue in relation to histogenesis and degree of differentiation of tumors. Double layer immunofluorescence (IMF) technique was used for the cellular localization of the antigen. CGSA was found in the cytoplasm of normal, reactive and neoplastic neuroglial cells. Well differentiated astrocytomas showed the strongest IMF reactions and largest number of IMF-positive cells. Tumors with histological signs of anaplasia displayed foci of IMF-negative cells irregularly distributed in the sections. There were no completely negative astrocytomas owing to a marked affinity of the specific astisera to the astrocytic cell line. In the oligodendrogliomas a smaller amount of the antigen was found than in the astrocytomas. Histological evidence of malignancy in these tumors was accompanied by strikingly small number of positive cells and weaker IMF reactions as compared to the well differentiated oligodendrogliomas. Anaplastic gliomas showed only traces of CGSA and non-glial tumors were entirely negative. The results suggest a deficiency of normal antigenic material in the neoplastic glia, particularly of oligodendrogliomas and anaplastic gliomas.

Animals↗
PubMed1979

Multiple molecular forms of glia maturation factor.

Glia maturation factor from the pig brain can be detected in two molecular forms: the high molecular weight form which is 200 000 dalton in size and the low molecular weight form which is 40 000 dalton in size, as determined by Sephadex gel filtration. The former accounts for 85% of the total biological activity extracted at physiologic pH. The proportion of the low molecular weight form increases following freeze-thawing and ion-exchange chromatography. In addition to the morphological effects, both forms possess mitogenic activity but no esteropeptidase activity. Both forms show similar enzyme susceptibility, being inactivated by papain, ficin and pronase but resistant to subtilisin, thermolysin and trypsin. The high molecular weight form is more resistant to denaturation by low pH, heating and urea than the low molecular weight form. The high molecular weight factor has an isoelectric point of 4.27 whereas the low molecular weight factor has one of 5.04.

Animals↗