摘要:

AbstractTransplantation of glial cells into demyelinating lesions in CNS offers an experimental approach which allows investigation of the complex interactions that occur between CNS glia, Schwann cells, and axons during remyelination and repair. Earlier studies have shown that (1) transplanted astrocytes are able to prevent Schwann cells from participating in CNS remyelination, but that they are only able to do so with the cooperation of cells of the oligodendrocyte lineage, and (2) transplanted mouse oligodendrocytes can remyelinate rat axons provided their rejection is controlled by immunosuppression. On the basis of these observations, we have been able to prevent the Schwann cell remyelination that normally follows ethidium bromide demyelination in the rat spinal cord by co‐transplanting isogeneic astrocytes with a potentially rejectable population of mouse oligodendrocyte lineage cells. Since male mouse cells were used it was possible to demonstrate their presence in immunosuppressed recipients using a mouse Y‐chromosome probe by in situ hydridisation. When myelinating mouse cells were rejected by removal of immunosuppression, the demyelinated axons were remyelinated by host oligodendrocytes rather than Schwann cells, whose entry was prevented by the persistence of the transplanted isogeneic astrocytes. The oligodendrocyte remyelination was extensive and rapid, indicating that the inflammation associated with cell rejection did not impede repair. If this host oligodendrocyte remyelination was prevented by local X‐irradiation, the lesion consisted of demyelinated axons surrounded by processes from the transplanted astrocytes. By this approach, it was possible to create an environment which resembled the chronic plaques of multiple sclerosis. Thus, these experiments demonstrate that in appropriate circumstances the temporary presence of a population of glial cells can alter the outcome of damage to the CNS. © 1995 Wiley‐L

ISSN:0894-1491    

DOI:10.1002/glia.440130202

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

年代:1995

数据来源: WILEY

摘要:

AbstractGlia are the predominant brain cells infected by the lentiviruses human immunodeficiency virus (HIV) and feline immunodeficiency virus (FIV). The importance of astrocytes in maintenance of central nervous system homeostasis suggests that astrocytes are likely to play a strategic role in the progression of neurological disease in lentiviral‐infected patients. In consideration of this postulate, the ability of FIV to cause injury by infection of cultured feline astroglia was examined via vital fluorescence assays. Intracellular Ca2+homeostasis, plasma membrane permeability and fluidity, and cytosolic glutathione (GSH) levels were evaluated. Although basal intracellular Ca2+was not significantly different between groups, FIV‐infected astroglia displayed both a significant delay in development of peak Ca2+levels following ionophore application and a decrease in the amount of Ca2+released from intracellular stores. Plasma membrane lipid mobility was increased in FIV‐infected cells within 24 h of infection. Glutathione levels were affected in a dose dependent fashion. With a standard viral inoculum there was a decrease in GSH which became significant after 8 days postinfection. With a high inoculum dose there was rapid loss of cell viability with an increase in GSH in surviving cells. We have identified several cellular processes altered in FIV‐infected astroglia and our findings suggest that FIV‐infection of feline astroglia affects cellular membranes, both structurally and functionally. © 1995 Wiley

ISSN:0894-1491    

DOI:10.1002/glia.440130203

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

年代:1995

数据来源: WILEY

摘要:

AbstractIt is becoming increasingly clear that astrocytes play very dynamic and interactive roles that are important for the normal functioning of the central nervous system. In culture, astrocytes express many receptors coupled to increases in intracellular calcium ([Ca2+]i). In vivo, it is likely that these receptors are important for the modulation of astrocytic functions such as the uptake of neurotransmitters and ions. Currently, however, very little is known about the expression or stimulation of such astrocytic receptors in vivo. To address this issue, confocal microscopy and calcium sensitive fluorescent dyes were used to examine the dynamic changes in astrocytic [Ca2+]i, within acutely isolated hippocampal slices. Astrocytes were subsequently identified by immunocytochemistry for glial fibrillary acidic protein. In this paper, we present data indicating that hippocampal astrocytes in situ respond to glutamate, kainate, α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA), 1‐aminocyclopentane‐trans‐1,3‐dicarboxylic acid (t‐ACPD), N‐methyl‐D‐aspartate (NMDA), and depolarization with increases in [Ca2+]i. The increases in [Ca2+]ioccurred in both the astrocytic cell bodies and the processes. Temporally the changes in [Ca2+]iwere very dynamic, and various patterns ranging from sustained elevations to oscillations of [Ca2+]iwere observed. Individual astrocytes responded to neuroligands selective for both ionotropic and metabotropic glutamate receptors with increases in [Ca2+]i. These findings indicate that astrocytes in vivo contain glutamatergic receptors coupled to increases in [C2+]iand are able to respond to neuronally released neurotransmit

ISSN:0894-1491    

DOI:10.1002/glia.440130204

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe injection of Fluoro‐Gold (FG) into the whisker pad of rats yields a stable fluorescent labeling of the motoneurons in the lateral facial subnucleus. Following resection of 8–10 mm of the facial nerve, the microglia phagocytose the FG‐preloaded neurons and assume the label. Employing this vital labeling of microglia in situ we studied the fate of sameaftercompletion of phagocytic activity. Starting at 56 days post resection (DPR) the FG‐labeled microglia spread out from the lateral facial subdivision and invaded the entire facial nucleus. The quantitative analysis of this redistribution of the fluorescent marker revealed a prolonged increase in the number of labeled microglia strictly proportional to the delayed loss of neurons. The differentiation between microglia and shrunken neurons was performed with the new method of immunoquenching: the staining of vibratome sections with anti‐rat neuron‐specific enolase (NSE) combined with an ABC‐HRP kit and DAB as detector totally extinguished (quenched) all fluorescence from the pre‐labeled facial motoneurons. The fluorescent microglia were additionally stained with GSA I‐B4and OX–42, which should completely quench all fluorescence in the section. However, a few small round cells, always closely opposed to neuronal perikarya, still fluoresced. These NSE‐negative, GSA I‐B4and OX–42 negative, but fluorescent cells may represent a new, immunologically uncharacterized microglial cell type, that participates in neuronophagia.

ISSN:0894-1491    

DOI:10.1002/glia.440130205

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe primary olfactory pathway contains non‐myelinating glial cells, called ensheathing cells, that exhibit a variety of phenotypes depending on their immediate environment. In vivo, these cells normally possess a mixture of astrocyte‐ and Schwann cell‐specific phenotypic features. When co‐cultured with dorsal root ganglion neurons, their phenotype can become more like that of a myelinating Schwann cell. The objective of this study was to determine whether ensheathing cells would express a myelinating phenotype in culture in the absence of neurons but in the presence of cAMP analogues that are known to induce the expression of myelin associated molecules in Schwann cell cultures. The ensheathing cell cultures were initiated using the nerve fiber layers of Theiler stage 23 rat olfactory bulb primordia and were fed for 1 day to 3 weeks with serum containing (1% or 10% FBS) or serum‐free media to which was added different concentrations of dBcAMP (0.1 to 1 mM) or forskolin (10 M). These cultures were double‐labelled with a rabbit polyclonal antibody to S100 in combination with mouse anti‐GAL‐C (01 and BRD1 hybridomas) or anti‐MBP monoclonal antibodies. The remaining cultures were double‐labeled with a rabbit polyclonal antibody to GFAP in combination with the BRD1 antibody. Treatment with dBcAMP or forskolin failed to induce ensheathing cells to express MBP regardless of the concentration. On the other hand, the treatment induced approximately one tenth of the cells to express GAL‐C, and virtually all of the cells to express GFAP. These results indicate that although ensheathing cells can synthesize myelin associated molecules, the cAMP second messenger system appears to play a lesser role in controlling the expression of a myelinating phenotype in ensheathing cells than it does in Schwann cells.

ISSN:0894-1491    

DOI:10.1002/glia.440130206

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

年代:1995

数据来源: WILEY

摘要:

AbstractThis study investigates glucagon binding in primary cultures of differentiated mouse astrocytes and the effect of glucagon on intracellular cAMP accumulation.Binding of125I‐glucagon (0.53 nM) to mouse astrocyte suspensions reached equilibrium after 10 min at 22°. Equilibrium binding corresponded to 46 · 15 pmol/mg protein (n = 3) representing approximately 10,000 occupied sites per cell at the tracer concentration used. Dissociation occurred with a half‐time of 2.5 min at 22°C and was not accelerated in the presence of unlabelled glucagon (1 M). Scatchard analysis suggested the presence of more than one class of binding site. The Ka for the higher affinity sites was 5.7–7.4 × 106M−1. The Ka for the lower affinity sites was 3.6–5.3 104M−1. The results suggest the presence of approximately 43,000 high affinity sites per cell. Binding was inhibited by unlabelled glucagon with an IC50of 50 nM but unaffected by insulin and somatostatin. However, no125I‐glucagon binding could be detected when intact monolayer cells attached to culture dishes were used.Glucagon stimulated cyclic‐AMP accumulation in both cell suspensions and intact monolayer cells in a dose‐dependent fashion. However high concentrations were required when compared to the receptor‐binding studies.Marked degradation of125I‐glucagon by astrocytes during binding experiments was observed and this was inhibited by unlabelled glucagon but also by insulin and desoctapeptide insuli

ISSN:0894-1491    

DOI:10.1002/glia.440130207

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

年代:1995

数据来源: WILEY

摘要:

AbstractUsing immunohistochemistry, we investigated changes in phosphotyrosine (P‐Tyr) immunoreactivity on the microglia of the rat substantia nigra (SN) following striatal ischemic injury produced by transient middle cerebral artery (MCA) occlusion. Anterograde axonal degeneration in the SN due to striatal ischemic injury was detected by depletion of calcineurin immunoreactivity in that region from 1 day after operation. From 3 days to 1 month (the longest period examined in this study) after MCA occlusion, there was a significant increase in P‐Tyr immunoreactivity in the SN ipsilateral to the MCA occlusion. Also, light microscopic observation showed that the microglia exhibited an increased immunoreactivity for P‐Tyr and characteristic morphological changes in the ipsilateral SN. The present results indicate that a signal transducing cascade(s) associated with tyrosine phosphorylation may be involved in the activation of the microglia in the SN responding to anterograde degeneration of the striatonigral pathway. © 1995 Wiley‐L

ISSN:0894-1491    

DOI:10.1002/glia.440130208

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

年代:1995

数据来源: WILEY

ISSN:0894-1491    

DOI:10.1002/glia.440130209

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

年代:1995

数据来源: WILEY

ISSN:0894-1491    

DOI:10.1002/glia.440130201

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

年代:1995

数据来源: WILEY