摘要:

AbstractA method to purify glial fibrillary acidic protein (GFAP) from mouse spinal cord is described, which permits the measurement of GFAP in the sciatic nerve of the twitcher mutant and control mouse. Cytoskeletal proteins from sciatic nerves and purified GFAP standards were electrophoresed on gel, transferred to nitrocellulose paper, and immunostained with anti‐GFAP antibody. From the immunostained, 51,000‐dalton band, we estimated about 200 ng GFAP per 50 μg of cytoskeletal protein in the twitcher sciatic nerve. The control nerve showed no detectable GFAP. Double‐labeled fluorescence immunocytochemistry showed that in the brainstem of twitcer mutant, GFAP and vimentin were coexpressed in the majority of astr

ISSN:0894-1491    

DOI:10.1002/glia.440010202

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

年代:1988

数据来源: WILEY

摘要:

AbstractUsing a new double‐labeling immunofluorescence technique, we assessed various growth factors on their ability to promote proliferation of cultured human glial cells. Cells studied were fetal astrocytes, fetal Schwann cells, adult astrocytes, and adult oligodendrocytes. Effective agents for fetal astrocytes were glial growth factor from the bovine pituitary, platelet‐derived growth factor, fibroblast growth factor, and 4β‐phorbol 12, 13‐dibutyrate. For fetal Schwann cells, mitogens were glial growth factor from the bovine pituitary, platelet‐derived growth factor, nerve growth factor, and 4β‐phorbol 12, 13‐dibutyrate. Adult astrocytes and oligodendrocytes did not normally divide in culture, and none of the agents tested were effective in inducing their proliferation. The report that interleukin‐2 was a mitogen for oligodendrocytes could not be replicated in the present study on any of the

ISSN:0894-1491    

DOI:10.1002/glia.440010203

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe two fibroblast growth factors called acidic and basic FGF (aFGF and bFGF) show a strong homology (55%) of their amino acid sequence (Esch et al.: Proc. Nat. Acad. Sci. USA 85:6507–6511, 1985). The effects of these factors on the rate of proliferation of rat astroblasts and on the expression of glutamine synthetase activity in cells grown in primary culture were investigated and compared under various culture conditions. In all the experimental conditions used, both growth factors triggered the proliferation of the cells to the same extent and with similar dose dependence. The mitogenic activities of aFGF and bFGF were potentiated similarly by heparan sulfate and by heparin, with a maximum stimulation of about 100% at 100 μg/ml heparin. Treatment of the cells with either of the two factors resulted in identical enhancement of the activity of glutamine synthetase relative to total proteins. These results suggest that both factors act either through the same membrane receptors or through different receptors that mediate nearly identical effec

ISSN:0894-1491    

DOI:10.1002/glia.440010204

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

年代:1988

数据来源: WILEY

摘要:

AbstractWe have previously shown that cultured astrocytes from neonatal rat cerebral cortex are depolarized by GABA. The underlying ionic mechanism, activation of a Cl−−conductance and responses to an agonist and antagonists were found to be similar to those of the neuronal GABAAreceptor (Kettenmann et al.: Brain Research 404:1–9, 1987; Kettenmann and Schachner: Journal of Neuroscience 5:3295–3301, 1985). To characterize further the pharmacological properties of the GABA receptor we have tested the influence of pentobarbital and benzodiazepines on the GABA response. Pentobarbital potentiated and prolonged the GABA‐induced depolarization and enhanced the velocity of the depolarization. Agonists of the neuronal benzodiazepine receptor, flunitrazepam, diazepam, and midazolam, increased the GABA‐induced depolarization. As in neurons, an antagonist of the benzodiazepine receptor, Ro 15‐1788, blocked the flunitrazepam‐induced enhancement of the GABA response. In contrast to their effects on neurons, the inverse agonists Ro 22‐7497 and DMCM increased the GABA‐induced depolarization. The ligand of the putative peripheral benzodiazepine binding site, Ro 5‐4864, did not show consistent effects on the GABA response.These studies confirm that cultured astrocytes express GABAAreceptors. This receptor is similar to the neuronal GABAAreceptor with regard to Cl−−conductance and its pharmacological responses to muscimol, bicuculline, picrotoxin, pentobarbital, and benzodiazepine agonists and an antagonist, but it is different in its responses to inverse agonists of the benzodiazepine site. The physiological role of the glial GABAArecep

ISSN:0894-1491    

DOI:10.1002/glia.440010205

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

年代:1988

数据来源: WILEY

摘要:

AbstractWe have compared highly purified fractions of oligodendrocyte plasma membrane to myelin by one‐ and two dimensional gel electrophoresis and found them to be distinct. The major myelin proteins—proteolipid protein (PLP), DM‐20, and myelin basic protein (MBP), which dominate the sodium dodecyl sulfate polyacrylamide gel electrophoresis pattern of myelin–were minor components of the plasmalemma. However, 2′,3′, cyclic nucleotide phosphodiesterase (CNPase) and myelin‐associated glycoprotein (MAG) were represented equally in both membranes. Labeling the cells with various precursors followed by isolation of plasmalemma revealed that newly synthesized PLP, DM‐20, CNPase, and MAG were incorporated into the plasma membrane of “floating” oligodendrocytes (i.e., nonattached to substratum). This was not so with MBP. Nevertheless, scattered patches of MBP were localized on the plasma membrane of intact cells using the immunogold method at the electron microscopic level. The data are consistent with the notion that MBP is not a constituent of the plasma membrane of mature oligodendrocytes (the MBP patches on intact cells are likely remnants from past association with myelin) but is rapidly associated with the plasmalemma of myelinating oligodendrocytes (i.e., attached cells). It is suggested that phosphorylation of MBP provides the triggering signal for plasma membrane association. In order to analyze the minor proteins in myelin and compare them to the plasma membrane by two‐dimensional gel electrophoresis, myelin was extracted with chloroform:methanol to remove PLP, DM‐20, and MBP. Even in the absence of PLP, DM‐20, and MBP the pattern of extracted myelin still differed from that of plasmalemma indicating that their minor protein compositions were not the same. Myelin was characterized by a group of proteins that clustered at pI 5.5–6.5 and Mr40,000–60,000 of which α‐tubulins, β‐tubulins, and actin are part: the plasmalemma had tubulins and actin but in different proportions. Our findings indicate that in addition to PLP, DM‐20, and MPB, myelin is also enriched relative to the pla

ISSN:0894-1491    

DOI:10.1002/glia.440010206

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe tissue architecture of low‐, medium‐, and high‐density primary mouse astroglial cultures was examined in horizontal and transverse planes using the electron microscope. It was found that the low‐density (colony) cultures consisted of a true monolayer, whereas the medium‐ and high‐density (confluent) cultures consisted of anywhere from two to seven overlapping sheets enclosing a substantial intercellular space. The presence of these multiple overlapping sheets in confluent astrocyte cultures should therefore be taken into consideration when interpreting data of cell‐membrane‐related phenomena suc

ISSN:0894-1491    

DOI:10.1002/glia.440010207

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe presence of immunocytochemically detectable membrane receptors for tetanus toxin, supposedly composed of higher gangliosides, is widely accepted as a marker of neuronal cells. We now demonstrate that Müller cells, a unique glial cell type of the vertebrate retina, possess specific tetanus toxin (TT)‐binding sites. Single cell suspensions were prepared from adult rat retina by a gentle dissociation method, and the Müller cells, unequivocally identified by their morphology, could be immunocytochemically double‐labeled by antisera to vimentin and to TT. The expression of complex gangliosides by identified Müller cells was also demonstrated by immunofluorescence labeling with the monoclonal antibody A2B5. Using the double‐immunolabeling method for the identification of Müller cells we show that specific tetanus toxin binding is acquired by these cells during postnatal maturation both in vivo and in vitro. In vivo the percentage of tetanus toxin‐positive Müller cells increases from 0% in 4‐day‐old animals to 10% on postnatal day 8, reaching the adult level of about 95–100% around day 30. In retinal monolayer cultures prepared from newborn rats, the majority (65%) of vimentin‐positive non‐neuronal cells became TT‐positive during a 2‐week culture period, indicating that this population of non‐neuronal cells represents differentiating Müller cells. Again, comparable results were obtained with A2B5, supporting the conclusion that Müllerian glia expresses surface molecules, which are normall

ISSN:0894-1491    

DOI:10.1002/glia.440010208

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

年代:1988

数据来源: WILEY

摘要:

AbstractIon‐selective double‐barreled microelectrodes were used to measure the activities of intracellular K+and Na+(a ik, a iNa) and the membrane potential (Em) in neuropile glial cells as well as extracellular K+(a eK) in the neuropile of segmental ganglia in the leech,Hirudo medicinalis. Bath‐application of carbachol resulted in a prominent membrane depolarization. This depolarization was accompanied by transient increases of a iNaand a eK, whereas a iKdecreased. It is suggested that the carbachol‐induced depolarization and the underlying ion activity changes are due to activation of an acetylcholine receptor‐coupled cation channel in the membrane of the

ISSN:0894-1491    

DOI:10.1002/glia.440010209

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

年代:1988

数据来源: WILEY

ISSN:0894-1491    

DOI:10.1002/glia.440010210

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

年代:1988

数据来源: WILEY

ISSN:0894-1491    

DOI:10.1002/glia.440010201

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

年代:1988

数据来源: WILEY