摘要:

AbstractExperimental allergic encephalomyelitis (EAE) was induced in adult Lewis rats with purified guinea pig CNS myelin and Freund' adjuvant. As soon as the very earliest clinical signs appeared the animals were perfused with fixatives and the spinal cord analyzed by electron microscopy, silver methods, and immunocytochemistry.Our findings suggest that in the early stages of EAE a sequence of events can be traced, although these events frequently overlap. The earliest morphological change appears to be astrocytic edema in both the cell body and processes. Increased amounts of glycogen particles and dispersion of glial filaments are prominent. These changes seem to occur just prior to the time when inflammatory cells begin to penetrate the capillary walls. Invasion of the neuropil mainly by macrophages and lymphocytes closely follows. Both macrophages and microglia seem to participate in phagocytosis of oligodendrocytes and myelin. Demyelination, however, is not a prominent feature at this early stage.

ISSN:0894-1491    

DOI:10.1002/glia.440030402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAstroglial cells were investigated by means of freeze‐fracture in normal rat and mouse brain, cell culture and human gliomas. Membranes of these cells were quantitatively analyzed for their intramembranous particles (IMPs) and orthogonal arrays of particles (OAPs). Measurement of the size of OAPs and IMPs has permitted the search for a correlation between the 7‐nm IMPs, which are distributed randomly in the membrane, and the subunits of OAPs (OAP‐Su, also 7 nm in diameter). Using cultured astroglial cells treated with basic fibroblast growth factor (bFGF), arginine vasopressin, or sorbitol, good evidence for a relationship between the density of 7‐nm IMPs and the size of OAPs can be demonstrated. These findings led to a hypothetical model of OAP modulation. A preliminary report has been published elsewhere (Neuhaus and Wolburg

ISSN:0894-1491    

DOI:10.1002/glia.440030403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAstroglial cells are known to proliferate during development of the nervous system, as well as during post‐traumatic gliosis. We have previously shown that the proliferation of cultured astrocytes can be stimulated by the urokinase‐type (uPA) of plasminogen activator (PA) and that astrocytes are able to release such uPA upon stimulation with basic fibroblast growth factor, which is known to act as a mitogen for these cells.Here we report studies on the effects of human interleukin‐1 (IL‐1) on the release of PA activity by cultured newborn rat astroglial cells. Whereas there is controversy in the literature as to whether IL‐1 stimulates multiplication of astroglial cells, we failed to observe such an effect in our system. We did observe, however, a dose‐dependent decrease in PA activity in the supernatant of the IL‐1 treated cultures. Further analysis revealed that this apparent decrease in PA release was in fact due to an increased release of plasminogen activator inhibitor (PAI). A similar IL‐1 induced increase in PAI release was also found to occur in cultures of transformed astrocytes (human glioma LN18) and in cultured Schwann cells, but not in cultures of neurons or neuronal tumour cells.Since protease inhibitors are known to possess neuritogenic properties, our results suggest that IL‐1, by its capacity to induce PAI, may promo

ISSN:0894-1491    

DOI:10.1002/glia.440030404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractEvidence of electrical and dye coupling between oligodendrocytes and astrocytes was sought in cultures of mouse spinal cord. Cell identity was verified using cell specific antigenic markers. In most experiments current was injected into oligodendrocytes while recording voltage in nearby astrocytes. Nine of 17 oligodendrocyteastrocyte cell pairs showed weak electrical coupling; the average estimated coupling ratio was 0.03 ± 0.06 (cf. 0.11 for oligodendrocyte‐oligodendrocyte and 0.44 for astrocyteastrocyte pairs; Kettenmann and Ransom:Glia, 1: 64–73, 1988). Application of 0.5 mM BaCl2or 44.6 mM CsCl depolarized astrocytes and oligodendrocytes and was estimated to increase the coupling ratio between these cells 3–5‐fold; these effects were rapid in onset and completely reversible. In 5 of 7 cases, oligodendrocyte‐astrocyte pairs that appeared uncoupled in normal solution exhibited coupling during Ba++or Cs+exposure. The actions of these cations are believed to be mediated by blockade of glial K+channels. Depolarization, per se, as induced by increasing [K+]o, did not increase coupling ratio. The fluorescent dye lucifer yellow (LY) was injected into 10 oligodendrocytes, 8 of which were electrically coupled to nearby astrocytes, and never passed into astrocytes in detectable quantities. Likewise, astrocytes injected with LY stained other astrocytes, but never oligodendrocytes. These findings document the presence of weak electrical coupling between astrocytes and oligodendrocytes, in the absence of dye coupling. Weak coupling of this sort could subserve metabolic interactions between these cells mediated by the passage of small but important molecules such as cyclic AMP, but would not allow strong electrical interactions. If such coupling among glial cells is widespread, it would constitute a “metabolic syncytium” that could serve to coordinate

ISSN:0894-1491    

DOI:10.1002/glia.440030405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractCrushed fish optic axons readily regenerate, while similarly injured rat optic axons do not; the reasons for the differences in regeneration ability may lie in differences in the environment of the axons. We have cultured glial cells from previously crushed optic nerves of fish and rat to determine whether a relationship exists between the ability to regenerate and the nature of the responses of the associated nonneuronal cells to injury. The glial cells were examined using indirect immunofluorescence with antibodies to known glial markers. In the rat cultures, mature GalC oligodendrocytes, which are known to be nonpermissive for axonal growth, were abundant. In contrast, in the fish cultures mature oligodendrocytes were rare, but A2B5positive cells were abundant. The high number of A2B5positive cells in the fish may suggest a high number of immature cells. This interpretation, however, should wait until evidence for glial cell lineage of the fish is available. Additional indication is provided also in the present study that the number of mature oligodendrocytes in the fish is regulated by elements external to the nerve. This study thus demonstrates an important difference between rat and fish optic nerves in the response of glial cells to the optic nerve injury.

ISSN:0894-1491    

DOI:10.1002/glia.440030406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAstroglia‐rich rat primary cultures can be grown in a glucose‐free medium containing 25 mM sorbitol. After 10 days under these conditions, the total number of cells and DNA content are reduced to 50–60% of those of control cultures, but remain constant thereafter. The specific activities of the sorbitol pathway enzymes, sorbitol dehydrogenase and aldose reductase, are increased 2.5‐fold and unchanged, respectively, if the cells are grown in the presence of sorbitol instead of glucose. Treatment with the aldose reductase inhibitor sorbinil does not decrease the number of cells cultured in the glucose‐free medium in the presence of sorbitol. Fructose is as good a substrate for the glial cells as sorbitol, whereas out of a number of other polyols tested only xylitol can support the primary cultures for more than 3 days. Neither neuron‐rich rat brain primary cultures nor rat glioma cells can be cultured in the sorbitol‐containing medium in the absence of glucose. With sorbitol substituting for glucose in the culture medium, effects of glucose deprivation on cellular functions like sugar transport and metabolism can be investigated in glial cultures for an extended p

ISSN:0894-1491    

DOI:10.1002/glia.440030407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractPrevious studies have shown that developing neurons of the basal forebrain and hippocampus are sensitive to thyroid hormone (Gould and Butcher:J. Neurosci., 9:3347–3358, 1989; Rami et al:Neuroscience, 19:1217–1226, 1986). In order to determine whether or not thyroid hormone influences the development of astrocytes in brain regions where neurons are affected, we performed vimentin and glial fibrillary acidic protein (GFAP) immunocytochemical and single‐section Golgi‐impregnation analyses on the basal forebrain and hippocampus of control and neonatally thyroid hormone treated rats. For purposes of comparison, glial cells of the pontomesencephalotegmental (PMT) region, a region where developing neurons are not morphologically affected by thyroid hormone imbalances (Gould and Butcher, op. cit.), were also examined. Neonatal thyroid hormone treatment resulted in a premature disappearance of vimentin‐immunoreactive radial glia in the basal forebrain and hippocampus. In addition, a premature appearance of GFAP‐immunoreactive astrocytes with mature morphological characteristics was observed in the basal forebrain and hippocampus of thyroid hormone treated animals. Quantitative analyses revealed significant increases in the density of GFAP‐immunostained astrocytes and in the cross‐sectional cell body area and the number of primary processes in Golgi‐impregnated astrocytes of the basal forebrain and hippocampus of animals treated neonatally with thyroid hormone. In contrast, no changes in any of these parameters were observed in glial cells of the PMT region with neonatal thyroid

ISSN:0894-1491    

DOI:10.1002/glia.440030408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAstrocytes, as well as Schwann cells (SC), can provide suitable substrata for embryonic neurites during development, but their abilities to support adult regenerating neurites have not been directly compared. The aim of the present study was to determine the ability of astrocytes to promote adult rat retinal ganglion cell (RGC) regeneration in vitro and to compare this to previously determined growth on the surface of Schwann cells. We prepared Type I astrocytes (Raff et al:J. Neurosci.3:1289–1300, 1983) from perinatal rats. These were subcultured and maintained in either a serum‐free medium for at least 2 weeks (stellate astrocytes with little immunoreactivity for laminin) or in serum containing medium for 7 to 10 days (flat and polygonal astrocytes with immunoreactivity for laminin). Stellate astrocytes might therefore represent mature astrocytes in vivo (Ard and Bunge:J. Neurosci.8:2844–2858, 1988), while flat astrocytes might resemble immature brain astrocytes (Liesi et al:J. Cell Biol.96:920–924, 1983). Adult RGC survival and axonal regrowth on these glia populations was compared to that observed on different SC populations, as previously reported (Baehr and Bunge:Exp. Neurol.106:27–40, 1989). Both astrocyte populations (either flat or stellate astrocytes) did not enhance RGC survival. Stellate astrocytes were less effective in supporting RGC axon regeneration than flat astrocytes. When these date were compared to RGC survival and axon growth on SC (Baehr and Bunge:Exp. Neurol.106:27–40, 1989) only “ctivated” mature SC populations were superior to astrocytes in enhancing RGC survival and neurite regrowth. These results suggest 1) that astrocytes and “immature” SC are similar in their ability to support RGC survival; 2) “activated” mature SC populations are significantly better than astrocytes and “immature” SC in enhancing RGC survival and neurite growth; 3) stellate (“mature”) astrocytes, although permissive for regrowing axons, are not a favorable substrate for regenerating adult RGC neurites, nor do they e

ISSN:0894-1491    

DOI:10.1002/glia.440030409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe reaction of astroglia was investigated after unilateral destruction of the dorsal lateral geniculate nucleus in the primary visual cortex of adult albino rats. The destruction of the dorsal lateral geniculate nucleus was performed by stereotaxic injections of ibotenic acid, and the location was verified in Nissl stained sections in each animal. Electron microscopic observations demonstrated the presence of degenerating axon terminals surrounded by hypertrophic astroglial processes mainly in layers III and IV of the ipsilateral primary visual cortex. The ipsilateral (impaired) and contralateral (control) sides of the primary visual cortex showed light microscopically a clearly differing appearance and distribution of glial fibrillary acidic protein (GFAP) immunoreactivity 7 to 11 days after the unilateral injection of ibotenic acid into the dorsal lateral geniculate nucleus. Whereas the control side of the primary visual cortex showed GFAP staining only in the subpial zone of layer I and close to the white matter, all layers of the impaired cortex showed an intense GFAP immunoreactivity. The increase in immunoreactivity was confined to the primary visual cortex. The extent of and increase in immunoreactivity was corroborated by image analysis. These findings were interpreted as a localized hypertrophy of astroglia caused by the anterograde degeneration of geniculocortical terminals. This hypertrophy is accompanied by an increase in GFAP, which may represent the stabilization of the cytoskeleton of newly formed glial processes involved in the rearrangement of the impaired neuropil.

ISSN:0894-1491    

DOI:10.1002/glia.440030410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractNeonatal administration of cytosine arabinoside (Ara‐C) induced marked hypoplasia of the mouse cerebellum. In 17–20‐day‐old mice with neonatal Ara‐C injections, the external granular layer was still preserved as an irregular cell laminae in the superficial part of the cerebellum, in contrast to its complete disappearance in normal animals at these stages. Immunohistochemical examination using anti‐glial fibrillary acidic protein and monoclonal antibody‐1D11 (Ono et al:Dev. Brain Res., 50:154–159, 1989) demonstrated malformation of a palisade‐like arrangement of labeled glial fibers in the superficial part of the Ara‐C treated mouse cerebellum. Furthermore, the immunoreactive astroglia were observed just beneath the pial membrane and their processes were oriented to the deeper part of

ISSN:0894-1491    

DOI:10.1002/glia.440030411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY