摘要:

AbstractThe serine protease inhibitor and neurite outgrowth promoter glia derived nexin (GDN) is expressed in the rat CNS during embryogenesis and persists in the olfactory system of the adult where receptor neurons are replaced throughout life. We investigated whether GDN‐immunoreactivity also appears in the adult at sites of synaptic rearrangement following nerve cell death and anterograde terminal degeneration in experimental models for Parkinson's disease. Rat substantia nigra was unilaterally lesioned by stereotaxic application of different toxins: 6‐hydroxydopamine, which selectively destroys dopaminergic neurons, the excitotoxic glutamate analog ibotenic acid, or the glutamate receptor agonists N‐methyl‐D‐aspartate and quisqualate, which cause circumscript lesions of the whole substantia nigra. Nerve cell death and astroglial reactivity were monitored by parallel cresyl staining and immunocytochemistry for glial fibrillary acidic protein, at survival times ranging from 2 to 100 days.Sustained de novo synthesis of GDN occurred in the dopamine depleted caudate putamen following excitotoxin or 6‐hydroxydopamine induced degeneration of the substantia nigra and of the nigrostriatal pathway provided that the lesions were nearly complete. This is consistent with compensatory changes occurring in deafferented caudate putamen and suggests a permissive role of GDN in neuronal plasticity.In the substantia nigra astroglia exhibited GDN‐immunoreactivity following excitotoxin injection but not after application of 6‐hydroxydopamine. Thus differences in action mechanisms of neurotoxins may have distinct consequences on the astrocyte mediated response of the same affected brain region. © 1994

ISSN:0360-4012    

DOI:10.1002/jnr.490370202

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

年代:1994

数据来源: WILEY

摘要:

AbstractBecause of its proximity to the central nervous system, the cerebrospinal fluid (CSF) represents an important source of T cells that potentially could mediate putative autoimmune diseases such as multiple sclerosis (MS). To overcome the low CSF cellularity, we evaluated culture conditions that could expand CSF T cells, with a focus on the expression of T‐cell receptor Vβ genes utilized by T cells specific for the potentially encephalitogenic autoantigen myelin basic protein (BP). Expansion of “activated” CSF cells with IL‐2/IL‐4 plus accessory cells optimally retained BP‐responsive T cells that over‐expressed Vβ1, Vβ2, Vβ;5, or Vβ;18, compared to expansion using supernatants from PHA‐stimulated blood cells, or anti‐CD3 antibody that led to different V gene bias and rare reactivity to BP. Sequential evaluation of paired CSF and blood samples from a relapsing remitting MS patient indicated that BP‐reactive T cells were present in CSF during the period of clinical activity, and the pattern of BP recognition in CSF was partially reflected in blood, even after CSF reactivity had dissipated during remission. Over‐expressed Vβ genes were not always constant, however, since in three sequential evaluations of a chronic progressive MS patient, Vβ genes over‐expressed in the first BP‐reactive CSF switched to a different Vβ gene bias that was present in the second and third CSF samples. Blood samples reflected each pattern of CSF Vβ gene bias, but retained the initial bias for at least 4 months after its disappearance from CSF. These data indicate that selective expansion of IL‐2/Il‐4‐responsive CSF cells favors growth of the BP‐reactive subpopulation, and, in a limited number of patients studied, reflected clinical disease activity. In comparison, blood T cells provided a partial but longer lasting reflection of the CSF BP reactivit

ISSN:0360-4012    

DOI:10.1002/jnr.490370203

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

年代:1994

数据来源: WILEY

摘要:

AbstractAn oncogene‐carrying repiication‐defective retrovirus was used to establish immortalised lines of murine glial cells. Primary cultures of early postnatal cerebellar cells were infected with a retrovirus based on the Murine Moloney Leukemia Virus containing a temperature‐sensitive mutant of the Simian Virus 40 large T antigen (SV40 T) oncogene and a gene coding for resistance to the antibiotic G418. Infected cells were selected in G418 and after several in vitro passages cells expressing the O4 antigen were established as a cell line. At a later time point O4‐positive single‐cell clones were established. Two different types of clones were obtained: (1) “plastic” clones consisting of cells which initially had a morphological and antigenic phenotype of young glial precursor cells but which gradually lost these features, and (2) “stable” cell clones including a clone with the immunological and electrophysiological characteristics of Schwann cells. Culture of the latter cells in the presence of 1 mM dibutyryl cyclic adenosine monophosphate for a period of at least 10 days induced a change in shape and a shift in antigen expression towards a more “diferentiated” maturation stage. When the SV40 T O4‐positive immortalised cell line isolated on the cell sorter was transplanted into demyelinated lesions in adult rats, cells were observed ensheathing axons and forming limited amounts of PNS‐type myelin.Glial cells immortalised with a temperature‐sensitive mutant of the SV40 T oncogene thus retain many physiological properties of their primary culture counterparts and can be induced to undergo limited differentiation in vitro and in vivo. These cell lines, which represent immature CNS glia or Schwann cells, are providing useful tools for investigating the role of cell surface antigens involved in neuron‐glial interac

ISSN:0360-4012    

DOI:10.1002/jnr.490370204

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

年代:1994

数据来源: WILEY

摘要:

AbstractAlthough normally quiescent, astrocytes in the adult brain respond to various types of brain injury by rapidly dividing, swelling, extending cellular processes, and expressing increased amounts of glial fibrillary acidic protein (GFAP). These phenomena are collectively referred to as “astrogliosis.” Similarly, astroglia in primary culture stop dividing when they attain confluency, yet, as seen in situ, they retain their proliferative capacity for extended periods and resume rapid division when subcultured. To examine the impact of glial division on secretion of neuritepromoting factors, conditioned medium (CM) was removed from subconfluent, newly confluent, and longterm confluent (“aged”) neonatal rat astrocyte cultures, and from aged confluent cultures that had been repassaged, “Lesioned” (scraping with a rubber policeman), or triturated 3 days before harvest. Secretion of neurite‐promoting factor(s) by glial cells into these CM was then assayed by treating neuroblastoma cultures with these various CM and quantitating neurite elaboration. Extensive neurite sprouting was elicited by CM from cultures just reaching confluency and from repassaged, lesioned, or triturated cultures. CM from aged confluent cultures did not induce sprouting. These results indicate that secretion of neurite‐promoting factors(s) is regulated by glial division, and suggest that gliosis in situ may contribute to neurite sprouting by similar mechanisms. Immunoblot analysis demonstrated the presence in CM of varying amounts of laminin and amyloid precursor protein (APP), including isoforms containing the Kunitz‐type protease inhibitor domain. CM from subconfluent cultures contained trace amounts of these protiens, but CM from cultures just reaching confluency contained significant amounts. Although CM from aged cultures contained barely detectable levels of either protein, trituration or repassage of aged cultures dramatically increased secretion of these proteins. APP‐and laminin‐enriched CM fractions promoted neuritogenesis to a similar level as respective unfractionated CM; anti‐APP and antilaminin antisera blocked this effect. Purified human brain APP promoted neuritogenesis when added to non‐conditioned medium and aged CM. Increased secretion of APP and laminin therefore mediates at least a portion of CM‐induced neuronal sprouting; these proteins may perform analogous functions during astrogliosis in s

ISSN:0360-4012    

DOI:10.1002/jnr.490370205

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe effect of dexamethasone on the expression of proteolipid protein (PLP) and myelin‐associated glycoprotein (MAG) genes was investigated in rat C6 glioma cells. The steady state level of the respective mRNA was quantitated by Northern blot analysis. The treatment of cells with dexamethasone transiently upregulated the expression of both genes with peak mRNA levels of approximately 10‐fold over control levels occurring at day 3 for the PLP gene and at day 5 for the MAG gene. The effect was directly related to the drug concentration in the range from 10−9to 10−5M. Combined exposure of the cells to dexamethasone and retinoic acid featured an additive effect on PLP gene expression, whereas MAG gene expression was depressed below detectability level. The dissimilarity in the response of the genes to dexamethasone and retinoic acid supports the contention that the genes are controlled by different mechanisms. Furthermore, the results indicate that the effects of dexamethasone and retinoic acid on the myelin genes are mediated by different regulatory pathways. © 1994 Wiley

ISSN:0360-4012    

DOI:10.1002/jnr.490370206

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

年代:1994

数据来源: WILEY

摘要:

AbstractLeukemia inhibitory factor (LIF) has several characteristics of a neurotrophic factor for sensory neurons. Here we have investigated whether LIF also supports the survival of axotomised sensory neurons in vivo. Newborn rat pups received a unilateral sciatic nerve transection and the injury site was treated with gelfoam soaked in phosphate buffered saline (PBS), nerve growth factor (NGF), or LIF. Neuronal nucleoli in the L5 dorsal root ganglia were counted, appropriate corrections applied, and the resultant neuronal loss expressed as a percentage of the contralateral intact side. In animals where LIF was administered neuronal loss was significantly reduced: 2 days after LIF treatment neuronal loss was 19.5% compared to 43% in PBS‐treated animals; 3 days after LIF treatment neuronal loss was 20.4% compared to 40.2% in PBS‐treated animals; however, 7 days after LIF treatment there was no significant reduction in the number of neurons lost. The degree of rescue of sensory neurons in vivo by LIF was found to be similar to NGF, which was not surprising as both factors supported the survival of a similar population of sensory neurons in vitro. Rescue was not observed when LIF‐containing gelfoam was placed away from the axotomised nerve, suggesting that LIF's action may be associated with its retrograde transport or direct signalling at the site of nerve injury. © 1994 Wiley‐L

ISSN:0360-4012    

DOI:10.1002/jnr.490370207

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn many regions of the rat central nervous system, oligodendrocytes develop from migratory A2B5+precursor cells. In the rat spinal cord, during early embryonic development the capacity for oligodendrogenesis appears to be restricted to ventral regions of the spinal cord, while cultures of postnatal rat spinal cord contain a distinct population of A2B5+astrocyte precursors. To determine if, as in other regions of the CNS, spinal cord A2B5+cells give rise directly to oligodendrocytes and astrocytes, the initial distribution, and subsequent dispersion, proliferation, and differentiation of spinal cord A2B5+cells have been examined in both explant and dissociated cell cultures. Spinal cord oligodendrocytes develop from A2B5+cells. At E14, A2B5+cells are restricted to ventral regions of the spinal cord and as development proceeds they become more uniformly distributed throughout the spinal cord. In explant cultures, greater than 95% of the explants that contain oligodendrocytes also contain A2B5+cells and a proportion of mature oligodendrocytes retain detectable A2B5 immunoreactivity briefly on their surface. The maturation of spinal cord oligodendrocyte precursors occurs in a number of distinct stages characterized by the expression of O4 immunoreactivity, which first appears at E16, and GC immunoreactivity, which first appears at E18. As spinal cord oligodendrocyte precursors acquire O4 immunoreactivity they appear to lose the ability to proliferate in response to PDGF but retain the ability to proliferate in response to bFGF, suggesting that the control of proliferation of oligodendrocyte precursors is, in part, dependent on their maturational state. In the presence of high serum, spinal cord A2B5+cells fail to develop in isolated E14 dorsal spinal cord cultures, while in ventral cultures they subsequently differentiate into A2B5+astrocytes suggesting that A2B5+astrocyte precursors are also initially ventrally located. Unlike oligodendrocyte differentiation, however, the differentiation of spinal cord A2B5+cells into astrocytes is delayed in early embryonic‐derived cultures compared to those from older animals. These observations suggest that local influences may regulate the timing of spinal cord A2B5+astrocyte development, but not spinal cord oligodendrocyte development. © 1994 Wiley‐Liss,

ISSN:0360-4012    

DOI:10.1002/jnr.490370208

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe hypothesis of satellite cell diversity in slow and fast mammalian muscles was tested by examining acetylcholinesterase (AChE) regulation in muscles regenerating (1) under conditions of muscle disuse (tenotomy, leg immobilization) in which the pattern of neural stimulation is changed, and (2) after cross‐transplantation when the regenerating muscle develops under a foreign neural stimulation pattern. Soleus (SOL) and extensor digitorum longus (EDL) muscles of the rat were allowed to regenerate after ischemic‐toxic injury either in their own sites or had been cross‐transplanted to the site of the other muscle. Molecular forms of AChE in regenerating muscles were analyzed by velocity sedimentation in linear sucrose gradients. Neither tenotomy nor limb immobilization significantly affected the characteristic pattern of AChE molecular forms in regenerating SOL muscles, suggesting that the neural stimulation pattern is probably not decisive for its induction. During an early phase of regeneration, the general pattern of AChE molecular forms in the cross‐transplanted regenerating muscle was predominantly determined by the type of its muscle of origin, and much less by the innervating nerve which exerted only a modest modifying effect. However, alkali‐resistant myofibrillar ATPase activity on which the separation of muscle fibers into type I and type II is based, was determined predominantly by the motor nerve innervating the regenerating muscle. Mature regenerated EDL muscles (13 weeks after injury) which had been innervated by the SOL nerve became virtually indistinguishable from the SOL muscles in regard to their pattern of AChE molecular forms. However, AChE patterns of mature regenerated SOL muscles that had been innervated by the EDL nerve still displayed some features of the SOL pattern. In regard to AChE regulation, muscle satellite cells from slow or fast rat muscles convey to their descendant myotubes the information shifting their initial development in the direction of either slow or fast muscle, respectively. The satellite cells in fast or slow muscles are, therefore, intrinsically different. Intrinsic information is expressed mostly during an early phase of regeneration whereas later on the regulatory influence of the motor nerve more or less predominates. © 1994 Wiley

ISSN:0360-4012    

DOI:10.1002/jnr.490370209

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe presence of acetylcholinesterase has been reported in chick dorsal root ganglia at early developmental stages although acetylcholine is not known to play a role in these ganglia. Recently, we reported that during development the level of acetylcholinesterase increases continuously and the enzyme becomes gradually expressed in all sensory neurons. These observations prompted the study of the developmental pattern of expression of other cholinergic markers, such as choline acetyltransferase (ChAT) and the high affinity transport mechanism for choline. ChAT activity is barely detectable at early developmental stages (E7) and increases markedly thereafter, with an activity profile similar to that described for acetylcholinesterase. A similar increase in enzyme activity is also observed when ChAT is measured in dorsal root ganglia explants and in dissociated cells in culture. The study of ChAT activity in cultured cells shows an increase over a period of 3 days, thus ruling out the hypothesis that motor fibers, still associated to the ganglia, may represent a possible source of the enzyme. Immunostaining of whole ganglia or cultured cells shows that ChAT immunoreactivity is not restricted to a specific neuronal subpopulation but appears as a common marker of sensory neurons. High affinity choline uptake, blocked by hemicholinium, is present in sensory neurons cultured from E7 dorsal root ganglia. Observations on cultured neurons from later stages (E18) indicate that choline transport is not a transient property of sensory neurons. These observations show a similar pattern of expression of several cholinergic markers during development. Such a pattern is maintained at significant levels also in mature ganglia. © 1994 Wiley‐Liss, I

ISSN:0360-4012    

DOI:10.1002/jnr.490370210

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

年代:1994

数据来源: WILEY

摘要:

AbstractGlia‐derived nexin/protease nexin‐1 (GDN/Pn‐1) is a serine protease inhibitor that is secreted by glial cells and fibroblasts in culture. In the adult mammalian nervous system it has been shown to be expressed in the olfactory system and by some glial cells in response to neuronal injury. In situ hybridization and immunocytochemical studies were performed to identify the structures expressing GDN/PN‐1 in the developing and adult rat brain. In contrast to a transient widespreat expression during pre‐and postnatal development, some brain structures constitutively express GDN/PN‐1. These include the olfactory nerve layer of the olfactory bulb, basal forebrain, striatum, pyramidal neurons of layer V in the cortex, thalamic nuclei, pars compacta of the substantia nigra, inferior and superior colliculi, and deep cerebellar nuclei. All of these parts, excluding the olfactory nerve layer, are characterized by a high neuronal cell density. Neurons in these regions were immunoreactive for GDN/PN‐1. Furthermore GDN/PN‐1 expression in cell lines showed that the active protein was synthesized and secreted from B104 but not from NB2a neuroblastoma cells. Although GDN/PN‐1 has only been reported to be synthesized by glia, the results presented here demonstrate that in addition, a subset of neurons express this protease inhibitor.

ISSN:0360-4012    

DOI:10.1002/jnr.490370211

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

年代:1994

数据来源: WILEY