摘要:

AbstractThe bewildering number of GABAAreceptor subunits, their regionally dependent expression in the brain, and their supernumerary expression in single cells present major challenges in studying the function of native GABAAreceptors. Which subunit combinations actually exist in native neurons? In this mini‐review, GABAAreceptor subunit diversity is considered in light of using the wealth of “structure‐function” information gained from studying recombinant receptor to predict the subunit composition and functional properties of native GABAAreceptors. © 1995 Wiley

ISSN:0360-4012    

DOI:10.1002/jnr.490410502

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

年代:1995

数据来源: WILEY

摘要:

AbstractWe previously reported that interleukin‐3 (IL‐3) acts as a neurotrophic factor for cholinergic neurons. However, it has not yet been determined whether the action is derived from the interaction of IL‐3 with IL‐3 receptors. As the first step to study IL‐3 receptors in the central nervous system, we examined the presence and localization of IL‐3 receptor‐associated antigen (IL‐3RAA) in mouse and rat brain. Immunohistochemically, IL‐3RAA, which is closely involved both in the IL‐3 binding to IL‐3 receptors and the tyrosine phosphorylation in the signal transduction for IL‐3 in hematopoietic cells, was demonstrated in neurons throughout the brain. This was confirmed in primary cultured neurons and neuronal cell lines by immunocytochemistry and flow cytometry. The staining intensity varied among regions and the most intense immunoreactivity for IL‐3RAA was found in large neurons in the magnocellular basal nuclei, pyramidal cells in the cerebral cortex, and neuronal cells in some nuclei of the brainstem. Not only cholinergic cell lines derived from the septal region but also other neuronal cell lines exhibited IL‐3RAA immunoreactivity by flow cytometry. Therefore, we conclude that IL‐3RAA is present in a wide variety of neurons in the brain including cholinergic neurons of the basal forebrain. Western blot analysis revealed that the candidates for IL‐3RAA are 145, 100, and 50 kDa proteins both in neuronal and IL‐3‐dependent

ISSN:0360-4012    

DOI:10.1002/jnr.490410503

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

年代:1995

数据来源: WILEY

摘要:

AbstractAntibodies were raised to two synthetic peptides with amino acid sequences encoded by a variable region of exons 10 and 11 of the tau gene. The affinity‐purified antibodies, designated E‐10 and E‐11, were used to determine whether PHF‐tau and normal tau differ in variants containing three or four repeats in the microtubule‐binding domain, respectively. Normal adult human brain was shown by gel electrophoresis to contain six isoforms of tau. All of the isoforms reacted with E‐11, whereas only four of them with slower electrophoretic mobility were recognized by E‐10. Fetal brain tau was readily recognized by E‐11 but reacted poorly with E‐10. In PHF preparations, E‐11 bound to all three polypeptides of PHF‐tau of 68 kD, 64 kD, and 60 kD and reacted intensely with a material smearing from the top of the gel to about the 50‐kD region. In contrast, E‐10 only weakly recognized the two higher molecular weight PHF‐tau polypeptides of 68 kD and 64 kD, as well as smeared material, and the binding was not affected by phosphatase treatment. Using recombinant tau with four repeats as a reference, the immunoreactivity of E‐10 with PHF‐tau was estimated to be approximately 5% of that of E‐11. By comparison, the immunoreactivity of E‐10 with four isoforms of normal tau was comparable to that of E‐11. These results indicate that the ratio of three vs. four repeat variants in PHF‐tau is higher than in normal tau and suggest that Alzheimer disease may be associated with the disproportional expression of fetal (or juvenile) forms of tau. Alternatively, the weak reactivity of PHF‐tau with E‐10 antibody could be due to post‐translational modifications other

ISSN:0360-4012    

DOI:10.1002/jnr.490410504

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

年代:1995

数据来源: WILEY

摘要:

AbstractAstrocytes and microglia play a critical role in the reaction of the central nervous system (CNS) to trauma. Although both astrocytes and microglia can produce it, accumulation of immunoreactive nerve growth factor (the prototype neurotrophin important for the survival of several classes of neurons) was observed selectively in cultured microglia and macrophages, rather than in astrocytes. Furthermore, microglia were found to display chemotaxis toward a localized source of nerve growth factor and, as demonstrated by autoradiography, take up extracellular nerve growth factor. These findings suggest that microglia, the brain's own macrophages, participate in the regulation of nerve growth factor availability in a site‐specific manner. This novel function may assume a general importance both in the CNS and the peripheral nervous system at critical times after trauma when this neurotrophin is needed for nerve cell survival. © 1995 Wiley‐Liss,

ISSN:0360-4012    

DOI:10.1002/jnr.490410505

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

年代:1995

数据来源: WILEY

摘要:

AbstractNeural expression of constitutive hsc70 mRNA and hyperthermia‐inducible hsp70 mRNA is examined using radioactive and non‐radioactive in situ hybridization procedures. A strong induction of hsp70 mRNA was noted in cell populations in cerebellar layers and in the brainstem which demonstrated expression of mRNA encoding proteolipid protein, an oligodendrocyte marker. The non‐radioactive in situ hybridization procedure using digoxigenin (DIG)‐UTP‐labeled riboprobes permitted improved signal localization, and stress‐inducible hsp70 mRNA was detected at the cytoplasmic cap areas of individual oligodendrocytes. Cell types which express constitutive members of the hsc/hsp70 multigene family were also identified. Neurons in the brainstem and in the deep white matter and molecular layer of the cerebellum showed expression of hsc70 mRNA while signal was not detected in adjacent glial cells. A neuron‐specific enolase riboprobe aided in the identification of neuronal cell types. The non‐radioactive DIG riboprobe revealed that hsc70 mRNA was highly localized to the cyto‐plasm of individual neurons. High constitutive levels of hsc70 in certain neurons may dampen hsp70 induction after hyperthermia in these cell populations. © 19

ISSN:0360-4012    

DOI:10.1002/jnr.490410506

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

年代:1995

数据来源: WILEY

摘要:

AbstractKindling is an animal model of epilepsy which is accompanied by morphological and biochemical changes in the brain, including sprouting of fibers and increased transmitter release. Here we have examined the immunocytochemical expression of (1) GAP‐43, a growth‐associated protein, which is a neuron‐specific PKC substrate, particularly expressed in development and regeneration and (2) glial fibrillary acidic protein (GFAP), part of the astrocytic cytoskeleton, after perforant path kiraling. Subsequent to kindling, GAP‐43 imimunoreacliviiy was increased in CAI stratum lacunosum‐moleculare and the inner and outer molecular layer of the fascia dentata. Other hippocampal subregions showed a lower increase. GFAP immunoreactivity was increased in the entire hippocampus, but especially in stratum lacunosum‐moleculare of the CAI and the hilus of fascia dentata. The difference between the number of GFAP‐positive profiles in the hippocampus of control rats and in fully kindled rats was found to be non‐significant. We interpret these findings as being related to both plastic neuronal changes and possible neuronal degeneration. © 1995

ISSN:0360-4012    

DOI:10.1002/jnr.490410507

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

年代:1995

数据来源: WILEY

摘要:

AbstractBased upon Blalock's complementary recognition approach, a complementary or antisense peptide (CP) was designed to the experimental autoiramune encephalomyelitis (EAE) epitope peptide, rat myelin basic protein (MBP) peptide 72‐82. This peptide (EAE CP) was shown to have some sequence similarities to T‐cell receptors (TCR) and MHC II molecules in a sequence homology search. Solid‐phase binding as‐says demonstrated specific and high affinity binding (3 and 4 μM) between the EAE CP and the rat and guinea pig EAE epitope peptides (Rt72‐82 and Gp69‐82), respectively. This EAE CP was also found to be immunogenic in rats in an ear swelling test for delayed type hypersensitivity (DTH) reactions and an ELISA for antibody responses. However, a rabbit antibody generated to EAE CP was shown to be unable to stain the Vβ8+EAE susceptible T‐cells in immunofluorescence analyses. This EAE CP was also used in attempts to down‐regulate EAE and the results showed that prior immunization with EAE CP in complete Freund's adjuvant could not prevent the Lewis rats from developing EAE. Although the data on sense‐antisense peptide interaction were positive and the EAE CP was immunogenic, the inability of EAE CP to regulate EAE indicates that the CP approach may not be generally applicable. ©

ISSN:0360-4012    

DOI:10.1002/jnr.490410508

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe specificity of nerve growth factor (NGF) action was examined by comparing early tyrosine phosphorylation events induced by NGF, epidermal growth factor (EGF), and basic fibroblast growth factor (bFGF). In PC12 cells, administration of either the differentiation factor NGF or the mitogenic factor EGF led to tyrosine phosphorylation of multiple polypeptides in the 100–110 kDa size range associated with PI‐3 kinase. However, NGF induced a more prolonged phosphorylation, relative to a transient EGF effect. In contrast, the differentiation factor bFGF failed to induce measurable tyrosine phosphorylation of PI‐3 kinase‐associated proteins. Similarly, NGF but not bFGF induced marked tyrosine phosphorylation of PLCγ, another early signaling molecule, suggesting that multiple pathways exist for promoting differentiation, and/or that these signaling molecules are not essential for differentiation. TrkA signaling was also compared between PC 12 cells and NIH‐3T3 cells heterologously expressing trkA, where receptor activation promotes mitogenesis. In this comparison, significant differences were observed in the tyrosine phosphorylation pattern of PI‐3 kinase‐associated polypeptides, suggesting the existence of cell type‐specific molecular interactions influencing trkA signaling. Mechanistically, NGF stimulation of PC12 cells resulted in a weak or possibly indirect association between trkA and PI‐3 kinase. Furthermore, NGF did not appear to activate or substantially alter the overall level of PI‐3 kinase activity, raising the possibility that ligand‐induced phosphorylation may serve instead to relocalize constitutively active PI‐3 kinase molecules within the cell. Taken together, data presented suggest that the temporal pattern of induced phosphorylation, the nature of induced associations with other phosphoproteins, and cell type‐specific components may all contribute to the generation of NGF signaling specifici

ISSN:0360-4012    

DOI:10.1002/jnr.490410509

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

年代:1995

数据来源: WILEY

摘要:

AbstractIn order to characterize the antiproliferative effect of methylazoxymethanol neuroepithelial cells derived from the rat striata primordia at embryonic day 14 have been exposed to graded doses of this compound. It was found that methylazoxymethanol application to striatal neuroblasts elicits a blockade of cell proliferation at a dose which does not interfere with cell survival. By using synchronized cells and short term exposures to this compound, we found that the antiproliferative effect of methylazoxymethanol is strikingly correlated to the number of cells actively dividing in culture, thus indicating that the cells targeted by methylazoxymethanol must be in an active mitotic phase. To test for the selectivity of actien of Methylazoxymethanol for dividing neuroblasts either cultures composed of mature proliferating astrocytes or muscle cells have been subjected to the same treatment. It has been observed that astrocytes proliferation was not affected by the dose of methylazoxymethanol shown to be effective on neuroepithelial cells. Finally we demonstrated that methylazoxymethanol is able only transiently to interfere with smooth muscle cell division, further supporting its selectivity of action within the developing CNS. © 1995 Wiley‐Liss, I

ISSN:0360-4012    

DOI:10.1002/jnr.490410510

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe proliferation of neonatal Schwann cells (SCs) in response to mitogenic agents has been well analyzed in vitro, but a limited range of mitogens have been defined. We investigated whether three identified neonatal SC mitogens [glial growth factor (GGF), platelet‐derived growth factor BB (PDGF‐BB), and basic fibroblast growth factor (bFGF)] are required to stimulate mitosis of adult SCs. Adult SCs were isolated from mouse sciatic nerves by mechanical and chemical dissociation, following three experimental steps: (1) culturing the dissociated cells for 24 hr in 10% FCS‐F12 medium, (2) culturing these cells in serum‐free medium for the next 48 hr, and (3) purifying adult SCs by differential adhesion. We describe a new method for preparation of SCs from peripheral nerves of adult mouse that provides 99.5% pure SCs populations at cell yields of greater than 3 × 103cells/mg of starting nerve wet weight within 5 culture days. Although mitosis of SCs in culture in response to mitogens requires the presence of serum, the complex nature of serum renders difficult a complete analysis of mitogens required for SCs DNA synthesis, so we examined the proliferating response of adult SCs to GGF, PDGF‐BB, and bFGF in serum‐free medium. GGF alone had mitogenicity for adult SCs in a dose‐dependent manner, and synergistic activation coupling with forskolin was not observed. Neither PDGF‐BB nor bFGF was mitogenic for adult SCs when used alone or with forskolin. Measurement of intracellular cyclic AMP levels in SCs cultured with these growth factors showed that cAMP levels were not changed by GGF and bFGF, and PDGF‐BB reduced the cAMP level to half of basal one. This study demonstrated that adult SCs could proliferate without serum factors and forskolin in response to GGF, and adult SCs were activated by GGF through a signal transduction pathway separate from the cyclic AMP‐dependent system. In addition, PDGF‐BB or bFGF has no mitogenic effect on adult SCs under serum‐free conditions

ISSN:0360-4012    

DOI:10.1002/jnr.490410511

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

年代:1995

数据来源: WILEY