摘要:

AbstractThe EDI monoclonal antibody recognizes an antigen in lysosomal membranes of phagocytes. The expression of this antigen in cells increases during phagocytic activity. Here we describe the expression of ED1‐immunoreactivity during the various stages of both acute (monophasic) and chronic relapsing experimental autoimmune encephalomyelitis (EAE) in the Lewis rat. During the first attack of acute and chronic relapsing EAE, ED1‐immunoreactivity was present in macrophages and in cells which displayed morphologic features of activated microglial cells (i.e., cells with thick short processes). At the ultrastructural level these cells were seen to contain phagocytosed myelin structures in lysosomes. ED1‐immunoreactivity in these cells was present in the cytoplasm near lysosomes. During the remission phase of acute EAE and the relapse phase of chronic relapsing EAE, ED1‐positive cells with dendritic morphology not only were present in or nearby lesions, but were also found at sites distant from lesions throughout large parts of the brain. These cells had a morphology comparable to microglial cells in normal brain. A major difference between animals which were in remission and animals which on day 25 were suffering from a relapse, was that the latter showed the presence of lesions with darkly stained round ED1‐positive macrophages and activated microglial cells. These results indicate that during a relapse, newly recruited bloodborne macrophages infiltrate the brain and, together with activated lymphocytes and microglial cells, recommence a new demyelination process. © 1994 Wiley

ISSN:0360-4012    

DOI:10.1002/jnr.490380402

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

年代:1994

数据来源: WILEY

摘要:

AbstractInjury to the central nervous system (CNS) either from trauma or due to demyelinating/degenerating diseases results in a typical response of astrocytes, termed astrogliosis. This reaction is characterized by astrocyte proliferation, extensive hypertrophy of nuclei, cell body, and cytoplasmic processes and an increase in immunodetectable glial fibrillary acidic protein (GFAP). GFAP accumulation may cause a physical barrier preventing the reestablishment of a functional environment. Our studies have aimed at modulating astrogliosis by inhibiting or delaying GFAP synthesis in damaged and reactive astrocytes. The present study investigates the use of a recombinant retrovirus expressing antisense GFAP RNA in controlling the response of mechanically injured astrocytes. A 650 bp fragment from the coding region of mouse GFAP cDNA was cloned in the antisense orientation under the control of long terminal repeat (LTR) promoter of Moloney murine leukemia virus. Increase in GFAP as detected by immunocytochemical staining in injured astrocytes was inhibited by treatment with retrovirus expressing antisense GFAP RNA. Also, astrocytes at the site of injury in these scratched cultures did not show cell body hypertrophy compared to control cultures. These observations demonstrate that the increase in GFAP at the site of injury can be inhibited using retroviral treatment and indicate the potential of retrovirus‐mediated gene transfer in modulating scar formation in the CNS in vivo. These studies also shed light on the role of GFAP in maintaining the morphology of astrocytes. © 1994 Wiley‐Liss,

ISSN:0360-4012    

DOI:10.1002/jnr.490380403

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe neuropeptide cholecystokinin (CCK) is involved in the regulation of female, but not male, reproductive behavior. In both sexes, estrogen regulates the expression of CCK in adulthood within the bed nucleus of the stria terminalis and medial amygdaloid nucleus. These areas are parts of an interconnected limbic system‐hypothalamic circuit, the development of which is influenced by estrogen during the early postnatal period. This is the same period during which central nervous system (CNS) expression of CCK is dramatically increased, suggesting that the male and female patterns of CCK expression may be the result of early postnatal exposure to estrogen. In the present experiment, the expression of preprocholecystokinin (pCCK) mRNA was determined by in situ hybridization with an isotopically labeled pCCK complementary RNA and emulsion autoradiography in animals whose neonatal and adult gonadal steroid levels had been manipulated. The number of pCCK‐expressing cells in animals that were gonadectomized as adults was determined by neonatal estrogen, but stimulation with steroids in adulthood induced a similar number of pCCK‐expressing cells in both sexes in the medial amygdala and bed nucleus of the stria terminalis. Neonatal treatment of females with estrogen or testosterone, followed by ovariectomy in adulthood, eliminated the sex difference in pCCK mRNA expression. Males treated neonatally with the aromatase inhibitor androstenedione (to block metabolism of testosterone to estrogen) and orchidectomized in adulthood had a level of pCCK mRNA expression that was similar to that of ovariectomized females. These data suggest that, during neonatal development, estrogen determines the constitutive expression of pCCK mRNA in the medial amygdala and bed nucleus of the stria terminalis, resulting in higher levels of pCCK mRNA expression in males than in females. However, exogenous gonadal steroids induce the same levels of pCCK mRNA expression in adult females, indicating that the levels of gonadal steroids and the patterns of their secretion are the predominant influences on the sexually dimorphic adult levels of pCCK mRNA expression. © 1994 Wiley‐L

ISSN:0360-4012    

DOI:10.1002/jnr.490380404

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

年代:1994

数据来源: WILEY

摘要:

AbstractAdenosine and its nucleotides adenosine triphosphate (ATP) and adenosine diphosphate (ADP) stimulate the proliferation of brain astrocytes in vitro and augment the effects of other growth factors. Following brain injury, hypoxia, or around solid tumors with necrotic centers, such as glioblastoma multiformes, high concentrations of adenine nucleotides and adenosine are released into the extracellular space; extracellular adenosine concentrations can rise 30–100‐fold to a concentration in excess of 100 μM. Increased concentrations of extracellular adenosine and adenine nucleotides may contribute to reactive astrocytic proliferation following brain injury. To test this hypothesis, adenosine, an adenosine analog 5′‐(N‐cyclopropyl)‐carboxamidoadenosine (CPCA), or ADP was microinjected into rat cortex. The number of glial fibrillary acidic prtein‐immunopositive cells was compared between the treated and contralateral saline‐injected hemispheres. Within 48 hr, astrocyte density around the CPCA (100 μM) infusion site was almost double that around the control saline infusion site. In hemispheres into which CPCA was infused, there was an increase in astrocytes in the subpial region along fiber tracts and around blood vessels, characteristic of Scherer's secondary structures found in association with malignant astrocytic brain tumors. The increased astrogliosis elicited by CPCA was abolished by coinfusion of the adenosine A2receptor antagonist 1,3‐dipropyl‐7‐methylxanthine (DPMX). While microinjection of adenosine (1 mM) failed to stimulate astrogliosis, microinjection of ADP (500 μM) also resulted in a significant reactive astrogliosis and accumulation of astrocytes similar to Scherer's secondary structures. These data indicate that purine nucleosides and nucleotides may play a role in reactive astrogliosis following injury and may also play a role in stimulating the astrocyte migration responsible for Scherer's secondary structures around astrogliomas

ISSN:0360-4012    

DOI:10.1002/jnr.490380405

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

年代:1994

数据来源: WILEY

摘要:

AbstractMonoamine‐activated α2‐macroglobulin (α2M) has recently been shown to inhibit the growth and survival of cholinergic neurons of the basal forebrain (Liebl and Koo: J Neurosci Res 35:170–182, 1993). The mechanism of this inhibitory effect is believed to involve the regulation of growth factor activities by α2M. The objectives of this study are to determine whether monoamine‐activated α2M can inhibit choline acetyltransferase (ChAT) activity of cholinergic basal forebrain neurons, and whether some common neurotrophins in the CNS can reverse the inhibition. This study demonstrates that both methylamine‐activated α2M (MA‐α2M) and serotonin‐activated α2M (5HT‐α2M) can dose‐dependently suppress the expression of normal basal levels of ChAT activity in embryonic rat basal forebrain cells in vitro, while normal α2M has little or no effect. As little as 0.35 μM monoamine‐activated α2M can suppress the ChAT activity, whereas either nerve growth factor (NGF) or brain‐derived neurotrophic factor (BDNF), but not neurotrophin‐3 (NT‐3), stimulates ChAT expression of these cells. The addition of either NGF or BDNF to the α2M‐suppressed cells can increase ChAT activity back to its normal levels, while NT‐3 can not. These results demonstrate that (1) monoamine‐activated α2M is a potent non‐cytotoxic inhibitor of the ChAT activity in cholinergic basal forebrain neurons, and (2) NGF and BDNF are capable of not only stimulating the ChAT activity but can also specifically reverse the α2M inhibition. The potential physiological role of monoamine‐activated α2M and neurotrophins in the degeneration and regeneration of cholinergic neurons is discussed. In addition, we propose that α2M may serve as an important tool for evaluating the roles of growth fa

ISSN:0360-4012    

DOI:10.1002/jnr.490380406

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

年代:1994

数据来源: WILEY

摘要:

AbstractMurine RSV‐M glioma cells were genetically labeled with a retroviral BAG vector carrying theEscherichia coliβ‐galactosidase gene. The X‐gal‐positive stable cell line RSV‐M/BAG was obtained by the FDG‐FACS method. To examine the behavior of glioma cells in the brain, we homografted RSV‐M/BAG cells into the brain of C3H/HeN mice as cell suspensions. Individual grafted glioma cells were easily detected by histochemical staining for B‐galactosidase (β‐gal). Three days after grafting, the β‐gal‐positive cells were mainly found in the subependymal zone of the lateral ventricle. In addition, some solitary labeled cells were found at locations distant from the injection sites. On the seventh day after implantation, tumor masses were observed and graft‐derived glioma cells were migrating bilaterally along the fibers in the corpus callosum. Other labeled cells extended into the brain parenchya via the perivascular (Virchow‐Robin) spaces. Rapid and extensive migration of individual glioma cells was thus clearly demonstrated by intracerebral transplantation of RSV‐M/BAG

ISSN:0360-4012    

DOI:10.1002/jnr.490380407

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe local synthesis and subsequent retrograde axonal transport of [35S]methionine‐labelled proteins was studied in the in vitro regenerating adult frog sciatic sensory axons. By the use of a three compartment culture system, proteins in the outgrowth region were selectively labelled. After 2 days in culture a rise in TCA‐insoluble radioactivity was detected in the dorsal root ganglia, which could be prevented by the addition of viblastine or 2,4‐dinitrophenol to the nerve proximal to the crush site. Two‐dimensional polyacrylamide gel electrophoresis of ganglionic proteins revealed a pattern of 35 labelled polypeptides with apparent molecular masses (Mm) ranging from<15 to 95 kDa and with isoelectric points (pI) ranging from 4.5 to 6.5. The major ones, representing about 75% of the activity in a gel, were of Mm/pI 47/5.4, 48/6.1, ©57/6.0, 62/5.2, 65/4.9–5.0, 65/5.2, and 81/5.4 respectively. One of these polypeptides (47/5.4) was identified as actin and another (81/5.4) as a member of the heat shock protein 70 family. The spots at 65/4.9‐‐5.0 were tubulin isoforms. There was a striking similarity between transported proteins on one hand, and proteins synthesized in the injured nerve on the other, with respect to the Mm/pI of at least 14 protein species. The results suggest that selected set of proteins, synthesized by non‐neuronal cells, e.g., Schwann cells, is transferred to the ganglionic cell bodies by retrograde axonal transport.© 199

ISSN:0360-4012    

DOI:10.1002/jnr.490380408

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe present study was designed to determine the extent to which cultured glial cells phagocytose normal central nervous system (CNS) myelin and CNS myelin opsonized with serum or purified antibody against myelin basic protein (MBP). Glial cells studied were mixed cultures (consisting of astrocytes, microglia, and oligodendrocytes) and enriched microglia established from adult human brain specimens and enriched astrocytes from fetal human brain. A human monocytic cell line, THP‐1, was included as a control. Uptake of125I‐labelled myelin was followed over a 24 hr time period. An assay of oxidative burst (30 min) and cytokine bioassays measuring IL‐1, IL‐6, and tumor necrosis factor (TNF) production (6‐‐48 hr) were used to investigate short‐ and longterm activation of phagocytosing cells. Maximum myelin uptake by phagocytosing glial cells occurred within 12‐‐24 hr following myelin incubation. Opsonization of myelin prior to the phagocytosis assay resulted in greater myelin uptake by mixed glial cell cultures, microglia, and THP‐1 cells over that of nontreated myelin. The magnitude of myelin phagocytosis by astrocytes was considerably lower than microglia and THP‐, and was not affected by myelin opsonization. Within 30 min of myelin phagocytosis, microglia and THP‐1 cells underwent oxidative burst; opsonization of myelin by purified anti‐MBP IgG and heat‐inactivated serum enhanced the microglial oxidative burst activity. Production of IL‐1, TNF, and most markedly IL‐6 by microglia was increased following 12‐‐24 hr of myelin ingestion. Our data demonstrate that myelin phagocytosis by adult human‐derived microglia occurs in vitro, is augmented when myelin is opsonized, and results in the activation of microglia as assessed by oxidative burst and cytoki

ISSN:0360-4012    

DOI:10.1002/jnr.490380409

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe regeneration of explants prepared from goldfish retinas with a prior crush of the optic nerve is stimulated by the sulphur amino acid, taurine. Serotonin has been reported to modify survival, proliferation, and outgrowth of nervous tissue. In the present work we evaluated the effect of serotonin and some serotonergic agonists on the neuritic outgrowth from goldfish retinal explants. Serotonin, its precursor, 5‐hydroxytryptophan, and the 5HT1Areceptor agonists, 8‐hydroxy‐2‐(di‐n‐propylamino)tetralin and busprione, inhibited the outgrowth. The blockers of serotonin uptake, imipramine and citalopram, were also inhibitors of neurite sprouting. Imipramine favoured the inhibitory effect of serotonin at 10 days in culture. The concentration of serotonin and its metabolite, 5‐hydroxyindoleacetic acid, decreased in the retina at 3 and 5 days after the crush of the optic nerve. Serotonin levels started to recover after 5 days post‐lesion, and the metabolite also increased. This indicates that the lesion increases the turnover rate of serotonin and this may be related to its role in regeneration. Serotonin concentration was elevated by the intraocular administration of its precursor, 5‐hydroxytryptophan, indicating that the capacity for synthesis was preserved after the crush, but that it was smaller in the post‐lesioned retinas. The trophic effect of taurine was impaired by a low concentration of serotonin, probably by opposing the final effect on growth via different targets. These results support a role of serotonin in the regeneration of goldfish retina probably through 5HT1Areceptors. ©

ISSN:0360-4012    

DOI:10.1002/jnr.490380410

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn earlier studies, we established glial cell cultures derived from aged (18‐month‐old) mouse cerebral hemispheres (MACH) and have maintained them frozen at various passages. These cultures were characterized immunocytochemically and consist of: 5% oligodendrocytes (GalC+), 75% astrocytes‐type 1 (GFAP+only), 15% astrocytes‐type 2 (GFAP++ A2B5+), and 5% progenitor glial cells (A2B5+only). In the present study, we isolated colonies from MACH passage 29 cultures and also colonies from MACH passage 19 transfected with the gene for SV40 large T antigen and further subcultured for 8 passages. Using double‐staining immunocytochemistry, we found in non‐transfected MACH passage 19 colonies consisting primarily of cells exhibiting only vimentin‐positive staining and are considered to be immature glioblasts; colonies consisting primarily of cells exhibiting GFAP++ vimentin+which are considered to be astrocytes at an intermediate stage of maturation; and colonies consisting predominantly of cells exhibiting GFAP+only which are considered to be mature astrocytes. In contrast, colonies isolated from transfected MACH cultures consisted primarily of vimentin+cells. In conclusion, astrocytes in cultures derived from aged brain continue to be variable as they are during development. However, their response to the microenvironment may differ during development and during aging. Thus, the availability of clones of mature and immature astrocytes offers the opportunity to study neuron‐glia interactions and the role of mature and immature astrocytes in neuronal aging and regeneration. © 1994

ISSN:0360-4012    

DOI:10.1002/jnr.490380411

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

年代:1994

数据来源: WILEY