摘要:

AbstractInterferon‐γ (IFN‐γ) is known to be an antiproliferative, differentiation agent in many cell types, including neuroblastoma. In this study, we determined the effects of IFN‐γ on cellular growth and expression of insulin‐like growth factor II (IGF‐II) and IGF receptors in the human neuroblastoma cell line SH‐SY5Y. Incubation of SH‐SY5Y cells in IFN‐γ (20–100 U/ml) induced the formation of long neuritic processes. IFN‐γ treatment also induced decreases in [3H]TdR incorporation, as well as serum‐dependent changes in cell number. Treatment with IFN‐γ reduced cell number 33% in the presence of serum but had no effect on cell number in the absence of serum. IGF‐II mRNA content was 60% inhibited by IFN‐γ, and was not serum dependent. The concentration of immunoreactive IGF‐II in SH‐SY5Y conditioned medium was also reduced in the presence of IFN‐γ, to less than half of control levels. In contrast, type I IGF receptor mRNA content was increased more than three‐fold after treatment with IFN‐γ and serum. Co‐incubation in IFN‐γ (20–100 U/ml) and IGF‐II on (3–10 nM) prevented the inhibitory effects of IFN‐γ on [3H]TdR ncorporation in serum‐free media. Our results suggest that IFN‐γ may inhibit DNA synthesis and cell growth by interfering with an

ISSN:0360-4012    

DOI:10.1002/jnr.490340502

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

年代:1993

数据来源: WILEY

摘要:

AbstractBasic fibroblast growth factor (bFGF) is a heparinbinding protein, expressing potent mitogenic and angiogenic properties. Elevated levels of bFGF have been identified in human gliomas and glioma cell lines, suggesting that bFGF expression is involved in the aberrant growth patterns associated with these tumors. In the present study, the influence of bFGF on additional parameters of glioma cell malignancy was evaluated utilizing three distinct methods to suppress bFGF expression or activity including antisense oligonucleotide primers, a neutralizing monoclonal antibody or an inhibitor of the agonist action of bFGF: (1) The addition of 30 μM bFGF‐specific antisense oligonucleotide primer to the human glioma cell line SNB‐19 resulted in a 55% inhibition in colony formation in soft agar. This effect was dose‐dependent and specific, as sense strand primer was ineffective in suppressing growth. In addition to exhibiting fewer colonies, antisense treatment significantly altered colony morphology. (2) SNB‐19 cell growth in culture was suppressed in the presence of a neutralizing bFGF‐specific monoclonal antibody. (3) Inositolhexakisphosphate, a newly identified antagonist of FGF binding and activity, suppressed SNB‐19 cell growth in soft agar culture. These results demonstrate that bFGF may regulate glioma growth and progression independent of its role in tumor angiogenesis and that bFGF release or secretion may be required for these actions. © 1993 Wi

ISSN:0360-4012    

DOI:10.1002/jnr.490340503

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

年代:1993

数据来源: WILEY

摘要:

AbstractDorsolateral and ventomedial surgical deafferentation of the hypothalamus were used to study the capacity of different types of neuropeptide Y‐containing axons afferent to the dorsal hypothalamus to regenerate through surgical lesions. The kinetics of the postlesional responses of transected neuropeptide Y‐axons was studied on 30–40 μm thick vibratome sections, either (i) by light or electron microscopy after peroxidase immunostaining for neuropeptide Y or (ii) by confocal microscopy after double fluorescence immunostaining for neuropeptide Y and for glial fibrillary acidic protein. The dorsolateral cut was found to sever 2 main pathways containing neuropeptide Y axons located, respectively, below the bed nucleus of the stria terminalis and in the perifornical region. In both regions transected fibers were found to abut onto the surgical lesion, but even 45 days after the lesion, they were very rarely observed to penetrate into the astroglial scar formed along the lesion. The ventromedial cut was found to sever numerous neuropeptide axons that originate in the underlying arcuate nucleus. Seven to 15 days after the lesion neuropeptide Y fibers located below this type of cut presented a dramatic increase in both their numerical density and their immunostaining intensity. With increasing post‐surgery times, an increased number of neuropeptide Y fibers was observed to penetrate and to cross the lesional scar formed by densely packed astrocytic processes. Electron microscope observations further demonstrated that 45 days after the lesion, numerous neuropeptide Y‐immunoreactive axonal profiles were included in the scar matrix, which appeared to be mainly composed of closely interdigitating astrocytic processes containing dense bundles of filaments. These data indicate that, in contrast to other neuropeptide Y neurons innervating the dorsal hypothalamus, neuropeptide Y neurons of the arcuate nucleus regenerate axons through the astroglial scar produced by a surgical lesion placed in the ventromedial hypothalamus. © 1993 Wile

ISSN:0360-4012    

DOI:10.1002/jnr.490340504

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe fine organization of lesional scars was studied in adult rats at the level of 2 types of surgical cuts aimed at deafferentating the dorsal hypothalamus from its neuropeptide‐Y innervation. These included (i) lesions located dorsolateral to the dorsal hypothalamus, which were shown to form a permanent obstacle to the regeneration of transected neuropeptide‐Y‐fibers, and (ii) lesions located in the ventromedial hypothalamus, where transected neuropeptide‐Y‐fibers were shown to penetrate and eventually cross the lesional area. Double labeling immunocytochemistry and conventional electron microscopy were used to identify various molecules produced by reactive astrocytes and to visualize their ultrastructural organization within the scars, respectively. In the different portions of the dorsolateral scars, the large majority of reactive astrocytes was characterized by a strong immunoreactivity to glial fibrillary acidic protein, vimentin, and embryonic (polysialilated) NCAM. Intense laminin‐immunoreactivity was also observed over large patches included in the scar. Electron microscope observations further indicated that the matrix of the scar was mainly composed of tightly packed astrocytic perikarya and processes connected by extended gap junctions. All around the extracellular and perivascular spaces, these astrocyte profiles were bordered by a thick basal lamina. Only scarce axonal profiles were detected in the core of the scar, most of which exhibited degenerative features. In the ventromedial hypothalamic scars, reactive astrocytes were found to exhibit intense immunoreactivity to both glial fibrillary acidic protein and vimentin. On the other hand, only slight immunostaining to embryonic NCAM and laminin were associated with this type of lesional scar. At the ultrastructural level, the main differences with the dorsolateral scars concerned (i) the gap junctions, which were less frequent and involved shorter portions of adjacent membranes; (ii) the basal lamina, which was essentially localized to the perivascular spaces; and (iii) the axonal profiles, which were frequently observed throughout the scar matrix. These data indicate that reactive astrocytes that formed the glial scar differ in the mediobasal hypothalamus and in other forebrain regions. This provides strong support for the hypothesis that the regeneration of neuropeptide‐Y axons through a mediobasal hypothalamic surgical cut depends mainly on the particular organization of the astroglial scar. © 1993 W

ISSN:0360-4012    

DOI:10.1002/jnr.490340505

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

年代:1993

数据来源: WILEY

摘要:

AbstractTo examine the regulation of nerve growth factor (NGF) gene expression with respect to neural trauma, we examined the effects of T cell‐derived lymphokines on NGF synthesis/secretion in cultured mouse astrocytes. Interleukin (IL)‐4 and IL‐5 significantly increased the amount of NGF secreted by astrocytes, whereas IL‐2, IL‐3, and IL‐6 had no significant effect. IL‐4 and IL‐5 produced marked increases in NGF mRNA levels in astrocytes as demonstrated by the reverse transcription‐polymerase chain reaction (RT‐PCR) method. The effect of IL‐4 and IL‐5 was greater in quiescent astrocytes than in growing cells. Neither increase in thymidine incorporation nor any morphological change was observed during the treatment with IL‐4 and IL‐5. The stimulatory effect of IL‐4 and IL‐5 on NGF synthesis was completely inhibited by the addition of anti‐IL‐4 monoclonal antibody and anti‐IL‐5 monoclonal antibody, respectively. The results indicate that IL‐4 and IL‐5 specifically trigger a cascade of events to regulate NGF synthesis in astrocytes, indepen

ISSN:0360-4012    

DOI:10.1002/jnr.490340506

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

年代:1993

数据来源: WILEY

摘要:

AbstractMn2+has been shown to promote cell–substrate adhesion and cell spreading in many cell culture systems. In this study, we present data demonstrating that Mn2+not only promotes spreading, but also induces process outgrowth in rat pheochromocytoma (PC12) cells. In the presence of 1.0 mM MnCl2, cell spreading was apparent by 6 hr, and nearly 50% of the exposed cells extended neurite‐like processes. These morphological effects of Mn2+were both time‐ and dose‐dependent. In the presence of cycloheximide, a protein synthesis inhibitor, both Mn2+‐induced spreading and neurite outgrowth were prevented, indicating that de novo protein synthesis is required for the effects of Mn2+to take place. Of the other divalent cations tested, Mg2+, Cd2+, Cu2+, Ni2+, and Zn2+were ineffective, and only Co2+partially mimicked the effects of Mn2+. Although Mn2+‐induced cell adhesion and spreading have been extensively studied, this is the first report that this divalent cation can cause neurite outgrowth. The neurite outgrowth‐promoting effects of Mn2+were distinct from those of nerve growth factor in that the response to Mn2+was considerably more rapid, but apparently lacked the ability to sustain continuous outgrowth and networking of neurites. Mn2+also induced the levels of GAP‐43 and peripherin, two proteins associated with neuronal differentiation of PC‐12 cells. In cells grown in serum‐free defined medium, Mn2+was capable of promoting neurite outgrowth when the cells were plated on surfaces pretreated with normal growth medium, vitronectin, or fibronectin, while it failed to cause these morphological changes in cells plated on untreated or poly‐D‐lysine‐coated substrata. Similarly, Mn2+also promoted neurite outgrowth from rat sympathetic neurons attached to laminin‐treated substrate, but had no effect on neurons maintained on substrate with polylysine only. The pentapeptide Gly‐Arg‐Gly‐Asp‐Ser nearly completely prevented the morphological effects of Mn2+on PC12 cells. These findings are consistent with a hypothesis that Mn2+‐mediated alteration of an RGD‐dependent extracellular matrix‐integrin interaction is responsible for the neu

ISSN:0360-4012    

DOI:10.1002/jnr.490340507

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe action of 5‐hydroxytryptamine (5HT) on nicotinic acetylcholine receptor (nAChR) channels was investigated in mouse myotubes, human cloned TE671/RD cells, andXenopus laevisoocytes. The decay of the ACh‐activated whole‐cell currents was reversibly accelerated in the presence of 5HT (10−5to 10−3M), in a dose‐dependent manner. 5HT also reduced the size and accelerated the decay of currents elicited by ACh inXenopusoocytes injected with mRNA extracted from C2 myotubes or Torpedo electroplaques, or oocytes injected with cloned mouse muscle AChR subunit mRNAs. The effect of 5HT was promptly reversed after washout, or by depolarizing the oocyte beyond −10 mV. In patch‐clamp recordings from myotubes, bath‐application of 5HT did not exert an indirect influence on the ACh‐activated channels within the patch membrane. In contrast, when the patch membrane was exposed to 5HT (10−6M), ACh unit responses appeared as bursts of short pulses. It is concluded that the regulation of ACh responses by 5HT results from a fast noncompetitive blocking action of nAChR‐channels. These results show that ligand‐gated channels, activated by their specific neurotransmitter, may be regulated by a different neurotransmitter through a direct action on the receptor molecul

ISSN:0360-4012    

DOI:10.1002/jnr.490340508

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

年代:1993

数据来源: WILEY

摘要:

AbstractProtein kinase C (PKC) and its potential role in myelin gene expression were investigated in primary cultured rat oligodendrocytes. The major myelin genes were expressed in a developmentally coordinated manner in cultured oligodendrocytes. PKC activity in these cells was similarly regulated with differential expression transiently and was most abundant in 9‐day cells in vitro. PKC‐α and PKC‐β mRNAs were present at low levels throughout development in these cells, and their expression increased in 18–25 day cells. Immunocytochemical colocalization of PKC with oligodendrocyte‐specific markers—O4, galactosyl cerebroside, MBP, and PLP—in enriched oligodendrocyte cultures suggested that the PKC predominantly contributed by oligodendrocytes. PKC inhibition resulting from long‐term exposure to 4β‐phorbol‐12,13‐dibutyrate (4β‐PDB) reduced steady‐state levels of MBP, PLP, MAG, CNP, and PKC‐α mRNAs, as detected by slot blots or in situ hybridization, and downregulated the oligodendrocyte‐specific markers O4, galactosyl cerebroside, and the major consitutent proteins MBP and PLP, as detected by immunocytochemistry. PKC‐mediated downmodulation of myelin gene expression was most profound in normally differentiating oligodendrocytes at or before the onset of myelin protein synthesis. Six‐day oligodendrocytes were most susceptible to such modulation. To elucidate the mechanism of reduction in various myelin gene messages upon modulation of PKC, we analyzed mRNA levels in oligodendrocytes, which were pretreated with either the transcriptional inhibitor actinomycin D or the protein synthesis blocker cycloheximide before exposure to 4β‐PDB. Our results demonstrate that the PKC inhibition‐mediated loss in myelin mRNA levels did not require the transcription of any genes, but appeared to be at least partially dependent on continuou

ISSN:0360-4012    

DOI:10.1002/jnr.490340509

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe development of cells of the oligodendroglial lineage, from immature progenitor to myelinating cells, occurs largely in a neuronal environment, yet little is known about specific interactions between these 2 cell types. We have tested the effects of medium conditioned by cultures of rat cerebral cortical neurons (CCM), cerebellar granule interneurons (GCM), and a dorsal root ganglion derived cell line (NDCM) on cells of the oligodendroglial lineage in culture. Different stages of the lineage were defined using the cell surface antigens GD3, 04, and GalC. CCM and NDCM were mitogenic for the early GD3+/04−oligodendroglial progenitor, whereas GCM was mitogenic for the later GD3+/04+stage. Neutralising antibodies to PDGF and bFGF were able to eliminate the mitogenic activity of NDCM and GCM, respectively, but did not abolish the mitogenic effect of CCM. We have demonstrated that neurons in primary culture from distinct CNS regions exert diffent influences on cells of the oligodendroglial lineage, and specifically that cortical neurons release an unknown mitogen for GD3+/04−oligodendroglial progenitors. © 1993 Wiley‐Lis

ISSN:0360-4012    

DOI:10.1002/jnr.490340510

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

年代:1993

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490340512

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

年代:1993

数据来源: WILEY