bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphine‐induced reciprocal alterations in Gαs and opioid peptide mRNA levels in discrete brain regions
Authors: Basheer R. , Tempel A. 
Published: January 2005

AbstractThe mechanisms involved in the development of morphine tolerance and dependence are still unknown. Recently much attention has been directed toward the changes in post receptor events. Opiate receptors, like other hormone and neurotransmitter receptors, have been shown to mediate their effects through guanine nucleotide binding proteins (G‐proteins). This, in turn, may cause alterations in intracellular events, one of which is transcription of specific genes. We investigated the changes in the levels of mRNA of proenkephalin (PPE) and prodynorphin (DYN) and the stimulatory G protein alpha subunit (Gαs) in adult morphine tolerant rats. Chronic morphine treatment induced reciprocal alterations in the levels of opioid peptide mRNA and Gαs in discrete brain regions. In striatum, PPE mRNA decreased by 49% (P < .01) and in hypothalamus. DYN mRNA showed a decrease of 21% (P < .01). In contrast, Gαs mRNA increased 20% (P < .01) in striatum and 97% (P < .01), in hypothalamus. In hippocampus the changes were reversed: PPE mRNA increased (55%, P <.05) and Gαs mRNA decreased (33%, P < .01). Frontal cortex exhibited a samll decrease in PPE (11.5%, P <.05) without any change on Gαs or DYN mRNA levels. These reciprocal alterations suggest an apposing mode of regulation of Gαs and PPE/DYN gene expression in morphine tolerant animals. © 1993 Wiley‐Liss, Inc.
Maintenance of glial plasticity with aging in C‐6 glial cells and normal astrocytes in culture: Responsiveness to opioid peptides
Authors: Kozlova M. , Kentroti S. , Vernadakis A. 
Published: January 2005

AbstractIn this study we used as glial cell models, early and late passage C‐6 glial cells, 2B clone, and advanced passages of glial cells derived from aged mouse cerebral hemispheres (MACH) to examine responsiveness to opioids. We have previously reported that early passage C‐6 glial cells, 2B clone, are bipotential and can be geared toward oligodendrocyte or astrocytic expression, whereas late passage C‐6 glial cells are astrocytic. In addition, MACH cultures have been previously characterized and consist of astrocytes type 1 and 2, some oligodendrocytes, and few glial precursors. In this study, early passage (17–20) and late passage (106–108) C‐6 glial cells or MACH cells of passages 16–19 were grown from plating time until harvesting, day 7 or 8, in DMEM + 10% FBS in the presence or absence of opioid peptides, Leu‐enkephalin (10−8 to 10−10 M) or its synthetic analog, dalargin (Tyr‐D‐Ala‐Gly‐Phe‐Leu‐Arg; 10−8 to 10−10 M). We examined for the activities of glutamine synthetase (GS) and cyclic nucleotide phosphohydrolase (CNP), enzyme markers for astrocytes and oligodendrocytes, respectively. We found that CNP activity was markedly increased in the early passage following opioid treatment, indicative of a shift to oligodendrocytic expression. In the late passage cells, already committed to astrocytic expression, opioid treatment enhanced GS activity suggesting that astrocytes respond to opioids. GS activity was markedly increased in MACH cultures grown in the presence of opioids with no changes in CNP. Thus, type 1 astrocytes, the predominant glial type in MACH cultures, responded to opioids. We conclude from these findings derived from two different glial models that regulation of astrocytes by microenvironmental signals appears to be maintained with aging. © 1993 Wiley‐Liss, Inc.
Cell‐type specific segregation of transcriptional expression of glial genes in the rat peripheral neurotumor RT4 cell lines
Authors: Hagiwara N. , Imada S. , Sueoka N. 
Published: January 2005

AbstractFour types of cells, RT4‐AC (stem cell type), RT4‐B and RT4‐E (neuronal cell types), and RT4‐D (glial cell type) were previously isolated from an ethylnitrosourea (ENU) induced rat peripheral neurotumor RT4. In a phenomenon termed cell‐type conversion, RT4‐AC spontaneously and permanently gives rise to the three other cell types in culture. In the RT4 system the expression of glial fibrillary acidic protein (GFAP) and S100β protein genes segregates in a celltype specific manner. To further characterize the RT4 family, the expression of four myelin‐forming glial genes—P0 glycoprotein, suppressed cAMP inducible POU (SCIP), 2′, 3′‐cyclic nucleotide 3′‐phosphodiesterase (CNP), and myelin basic protein (MBP)—has been studied in the RT4 cell lines. In addition to these genes, the expression of the lowaffinity nerve growth factor (LNGF) receptor (expressed in immature Schwann cells) has been examined. We have found the following results. (1) The stem cell type RT4‐AC and the glial cell type RT4‐D express mRNA transcripts of P0, SCIP, and CNP (the larger form, 2.8 kb), and the amount of mRNA of these genes was increased by forskolin. (2) RT4‐AC and RT4‐D also express a low level of MBP mRNA upon forskolin treatment. (3) The neuronal cell types RT4‐B and RT4‐E do not express any of these myelinforming glial genes with or without forskolin treatment. (4) The LNGF receptor mRNA is expressed in RT4‐AC and RT4‐D and at a lower level in RT4‐B; its expression is stimulated by forskolin. © 1993 Wiley‐Liss, Inc.
Isolation and characterization of Bsk, a growth factor receptor‐like tyrosine kinase associated with the limbic system
Authors: Zhou R. , Copeland T. D. , Kromer L. F. , Schulz N. T. 
Published: January 2005

AbstractNeuronal degeneration has been shown to be involved in various neurological disorders. Growth/trophic factors and their receptors are known to be important for the regeneration and survival of neurons. We report here the molecular cloning of a receptor‐like protein tyrosine kinase, bsk, (for brain specific kinase). Bsk is highly related to the eph/elk receptor like kinase family members. Northern blot analysis shows that is is expressed specifically in the brain, with no expression detected in adult heart, spleen, lung, liver, skeletal muscle, and kidney. In situ hybridization analysis of adult mouse brain sections indicates that bsk is expressed at high levels in the hippocampus, tenia tects, indusium griseum, and the piriform cortex, major components of the limbic system that are important for learning and memory. In addition, elevated levels of expression are found in other areas of the limbic system such as the amygdala, medial septum, and nucleus of the diagonal band, and in the olfactory bulb, which has close connections to the limbic system. The highest level of expression is found in the CA3 region of the hippocampus and the pyramidal cell layer of the piriform cortex. In 16.5 day mouse embryos, bsk is expressed predominantly in the primordial cortex of the telencephalon. An antibody against a C‐terminal peptide of bsk recognized a 105 kD protein in the 16.5 day embryonic head extract. Our analysis shows that bsk is a growth factor receptor‐like protein tyrosine kinase and that its greatest expression in the adult brain is associated with components of the limbic system. © 1994 Wiley‐Liss, Inc.
Glia‐derived nexin/protease nexin‐1 is expressed by a subset of neurons in the rat brain
Authors: Reinhard E. , Suidan H. S. , Pavlik A. , Monard D. 
Published: January 2005

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. © Wiley‐Liss, Inc.
Involvement of protein kinase C in cAMP regulation of myelin basic protein gene expression
Authors: Anderson S. , Miskimins R. 
Published: January 2005

AbstractSince synthesis of myelin components has been seen to be stimulated by cAMP in both oligodendrocytes and Schwann cells we have begun investigating the specific sequence(s) in the 5′ flanking region of the myelin basic protein (MBP) gene that are responsible for the induction of MBP transcription by cAMP. Using stably transfected cell lines containing various deletions of the MBP promoter directing the bacterial chloramphenicol acetyltransferase (CAT) gene we have identified a region of the MBP gene that is inhibitory to stimulation by increased cAMP levels. This inhibition can be overcome by pretreating the cells with 12‐O‐tetradecanoylphorbol 13‐acetate (TPA) for 48 hr. The effects on MBP gene expression modulated by TPA and cAMP involve altered DNA‐protein interactions in the 5′ end of the MBP promoter. The effect of TPA also appears to be mediated by down‐regulation of protein kinase C. © 1994 Wiley‐Liss, Inc.
Neuropeptide role of both peptide YY and neuropeptide Y in vertebrates suggested by abundant expression of their mRNAS in a cyclostome brain
Authors: Söderberg C. , Pieribone V. A. , Dahlstrand J. , Brodin L. , Larhammar D. 
Published: January 2005

AbstractThe evolution of the neuropeptide Y (NPY) family of peptides has been unclear despite sequence information from many vertebrates. We describe here two NPY‐related peptides deduced from cDNA clones of the river lamprey (Lampetra fluviatilis), a cyclostome providing one of the best models of a primitive vertebrate brain. One peptide corresponds to NPY as it has 83% identity to human NPY and its mRNA is expressed in the lateral brainstem, dorsal spinal cord and retina. The second lamprey peptide corresponds anatomically to peptide YY (PYY) as its mRNA is found in gut cells and in medial brainstem neurons. Its sequence is 60–70% identical to both PYY and NPY of mammals. These data suggest that the gene duplication leading to NPY and PYY had already occurred in the ancestral vertebrate 450 million years ago. The expression of the presumed PYY homolog in both gut and central nervous system indicates that PYY has served the dual role as a hormone and a neuropeptide from an early stage in vertebrate evolution. The similarities in the location of NPY‐ and PYY‐expressing cells between lamprey and mammals suggest that the functions of these peptides may have been conserved. © 1994 Wiley‐Liss, Inc.
Nerve growth factor regulates the subcellular localization of the nerve growth factor‐inducible protein PC4 in PC12 cells
Authors: Guardavaccaro D. , Montagnoli A. , Ciotti M. T. , Gatti A. , Lotti L. , Di Lazzaro C. , Torrisi M. R. , Tirone F. 
Published: January 2005

AbstractThe immediate early gene (IEG) PC4, which encodes a protein related to γ interferon, is activated at the onset of the neuronal differentiation induced by nerve growth factor (NGF) in PC12 cells. With an antibody raised to a bacterial β gal‐PC4 fusion protein, the PC4 protein is detected as an immunoreactive molecular species of 49 kDa, whose synthesis is rapidly induced by NGF in parallel with the induction of its mRNA. Immunofluorescence, electron microscopy and subfractionation studies indicate that the PC4 immunoreactivity is localized in the cytoplasm of PC12 cells, where it is increased transiently by NGF within 3 hr of treatment. In addition, the PC4 immunoreactivity presents an NGF‐dependent pattern of intracellular localization. In fact, within 3 hr after addition of NGF, PC4 is also significantly expressed on the inner face of the plasma membrane, to which it is physically associated. After longer NGF treatment, PC4 disappears from the plasma membrane and appears in the nucleus, with reduced cytoplasmic expression. Localization in the nucleus is reversed by removal of NGF and closely parallels changes in the state of differentiation of the cell. The existence within the PC4 protein of a consensus sequence for the addition of myristic acid and of a putative sequence for the nuclear localization suggests possible mechanisms for the NGF‐dependent redistribution. For an NGF‐inducible IEG product, such growth factor‐dependent localization of PC4 is a novel type of regulation in the pathways from the NGF receptor to the adjacent membrane proteins and to the nucleus. © 1994 Wiley‐Liss, Inc.
Involvement of glutamate receptors, lipases, and phospholipases in long‐term potentiation and neurodegeneration
Authors: Farooqui A. A. , Horrocks L. A. 
Published: January 2005

AbstractGlutamate is the primary excitatory amino acid in the mammalian central nervous system. Normal excitation of glutamate receptors initiates the stimulation of phospholipases and lipases with the generation of second messengers that are necessary for normal cell function. The overstimulation of glutamate receptors can initiate a cascade of biochemical events including stimulation of membrane phospholipid turnover, excessive calcium entry, abnormal phosphorylation, and proteolysis. These events may be responsible for neuronal injury and degeneration found in Alzheimer disease, ischemia, spinal cord trauma, epilepsy, and Huntington disease.
L‐glutamate‐stimulated taurine release from rat cerebral cultured astrocytes
Authors: Koyama Y. , Ishibashi T. , Tanaka K. , Baba A. 
Published: January 2005

AbstractWe characterized L‐glutamate‐stimulated taurine release from cultured astrocytes prepared from rat cerebrum. L‐glutamate (0.5 mM) stimulated release of 3H‐labeled and endogenous taurine, where the rate of release reached maximum in 40 min. L‐glutamate increased astrocytic volume [3H‐O‐methyl‐D‐glucose (3H‐OMG) space] with a similar time course to 3H‐taurine release. Quisqualate, L‐aspartate, DL‐homocysteate, and L‐cysteate increased both astrocytic 3H‐OMG space and 3H‐taurine release from cultured astrocytes, while kainate (1 mM) stimulated 3H‐taurine release without affecting astrocytic volume. N‐methyl‐D‐aspartate had no effect on 3H‐taurine release and astrocytic volume. Treatment of astrocytes with dibutyryl cAMP reduced the effect of kainate on 3H‐taurine release. L‐glutamate‐stimulated 3H‐taurine release was attenuated by removal of extracellular Cl− and in hyperosmotic medium, which prevented L‐glutamate‐induced increase in 3H‐OMG space of cultured astrocytes. These results indicate that L‐glutamate stimulates taurine release from astrocytes through swelling‐triggered mechanisms and that kainate causes the release through volume‐independent mechanisms. © 1994 Wiley‐Liss, Inc.
Study of the phorbol ester effect on Alzheimer amyloid precursor processing: Sequence requirements and involvement of a Cholera toxin sensitive protein
Authors: Efthimiopoulos S. , Felsenstein K. M. , Sambamurti K. , Robakis N. K. , Refolo L. M. 
Published: January 2005

AbstractPhorbol esters (PDBu) stimulate α‐secretase cleavage and secretion of the Alzheimer amyloid precursor protein (APP). To determine whether any cytoplasmic residues or sequence motifs mediate the PDBu effect on APP processing, this region of APP was altered by point mutations or deletions. To differentiate the mutated APP from the endogenous APP, the APP751 ectodomain between amino acids 1 and 647 was replaced by a human secreted alkaline phosphatase derivative (SEAP). The resultant fusion protein (SEAP‐APP751) was cleaved by α‐secretase at the same site as full‐length APP, and its secretion was stimulated by PDBu at a level similar to APP751. However, PDBu‐stimulated secretion of the SEAP‐APP751 fusion protein reached its maximum level after 30 min of treatment, while secretion of APP751 reached its maximum after 60 min, suggesting that the APP ectodomain affects the kinetics of APP secretion.Mutation of the cytoplasmic serines to alanines had no effect on the PDBu‐stimulated secretion of the SEAP‐APP, indicating that protein kinase C (PKC) phosphorylation of the cytoplasmic domain of APP is not important for stimulation of APP secretion. Similarly, deletion of the cytoplasmic domain between amino acids 719 and 751 had no effect on the PDBu‐stimulated secretion. However, deletion of amino acids 707–751 resulted in a significant increase in the secretory cleavage of the SEAP‐APP707ΔC construct, suggesting that the sequence 707–719 is important for the regulated secretion of APP.Cholera toxin, but not pertussis toxin, reduced the PDBu‐induced secretion of APP by more than two‐fold, suggesting that the PDBu response may be modulated by a cholera toxin sensitive heterotrimeric G‐protein. © 1994 Wiley‐Liss, Inc.
Preparation and affinity purification of a novel, biologically active, CNTF fusion protein
Authors: Rabinovsky E. D. , Browder D. P. , McManaman J. L. 
Published: January 2005

AbstractA biologically active fusion protein comprising a short hydrophilic leader peptide fused to the N‐terminus of rat CNTF was generated using commercially available materials. The coding region for rat CNTF was sub‐cloned into the pFLAG‐1 vector and transfected into the JM 109 strain of E. coli. The transfected cells expressed high levels of the fusion protein (FLAG‐CNTF) following induction by isopropyl β‐D‐thiogalactoside (IPTG). FLAG‐CNTF is expressed as insoluble material that was resolubilized by extraction with guanidine hydrochloride and purified by immuno‐affinity chromatography. Analysis of the purified material by reverse phase HPLC and Western blot analysis indicated that FLAG‐CNTF was composed of two closely related species that are greater than 99% pure after affinity chromatography. The purified FLAG‐CNTF migrated as a 27 KD doublet on SDS polyacrylamide gel electrophoresis. Both bands of the doublet were shown to contain the FLAG peptide and CNTF by Western blot analysis, and amino acid sequence analysis demonstrated a single amino acid sequence corresponding to FLAG peptide and the N‐terminus of CNTF. The purified fusion protein was tested for biological activity using the IMR‐32 human neuroblastoma cell line. Treatment of IMR‐32 cells with FLAG‐CNTF increased the level of choline acetyltransferase (ChAT) in these cells 2–3‐fold over that of control cells in a dose dependent manner. A direct comparison of the effects of FLAG‐CNTF and recombinant human CNTF on IMR‐32 ChAT activity showed that both factors exhibited similar potencies. Our studies demonstrate the use of simple, commercially available, recombinant technology to efficiently generate large quantities of purified, biologically active CNTF. © 1994 Wiley‐Liss, Inc.
Basic fibroblast growth factor improves recovery after chemically induced breakdown of myelin‐like membranes in pure oligodendrocyte cultures
Authors: Fressinaud C. , Vallat J. M. 
Published: January 2005

AbstractThe putative role of growth factors in remyelination was investigated in pure oligodendrocyte (OL) secondary cultures derived from newborn rat brain. These cells form myelin‐like membranes and were used as a model system for toxic attack. A 24 hr treatment with 2.10–5 M lysophosphatidylcholine (LPC) induced a loss of 59% of the cells in these cultures, with a 64% reduction in [125I]‐iododeoxyuridine incroporation compared to untreated controls. An absence of processes and myelin‐like sheaths was observed in the remaining cells. Numerous intractoplasmic inclusions were observed on transmission electron microscopy. Immunocytochemical studies with A2B5 monoclonal antibody (mAb), which recognizes oligodendrocyte‐type 2 astrocyte (O‐2A) precursors, OL‐1 mAb (directed against cell surface sulfatides), and anti‐myelin basic protein (anti‐MBP) antibody showed that the entire OL lineage was affected at all stages of maturation. A 3 day treatment with 10 ng/ml basic fibroblast growth factor (bFGF) induced reconstruction of myelin‐like membranes, albeit less compacted than in untreated controls. The doubling in number of cells and the 46% increase in [125I]‐iododeoxyuridine incorporation was due essentially to proliferation of O‐2A progenitors. These results indicate that if bFGF release occurs during demyelination, it may participate in myelin repair mechanisms in the central nervous system. © 1994 Wiley‐Liss, Inc.
Secretion of nerve growth factor from septum stimulates neurite outgrowth and release of the amyloid protein precursor of Alzheimer's disease from hippocampal explants
Authors: Clarris H. J. , Nurcombe V. , Small D. H. , Beyreuther K. , Masters C. L. 
Published: January 2005

AbstractAlzheimer's disease (AD) is characterized by the deposition of amyloid in the extracellular and intracellular compartments of the cerebral cortex. The extracellular amyloid consists of a protein (βA4) which is derived from a larger precursor, the amyloid protein precursor (APP). Several studies have implicated APP in the regulation of neurite outgrowth during development, although the precise function of APP remains unknown. To examine the role of APP in the regulation of neutrite outgrowth from hippocampal neurons, an explant culture system was developed. Explants of E18 mouse hippocampus were found to extend neurites when co‐cultured with explants of E18 mouse septum. This finding demonstrated that the septum can release a neurite outgrowth‐promoting factor (NOPF). As nerve growth factor (NGF) was also able to stimulate neurite outgrowth from the hippocampal explants, this suggested that the NOPF might be NGF. Immunoprecipitation of NGF from septal conditioned medium using a specific monoclonal antibody (27/21) completely blocked the neurite outgrowth‐promoting effect, supporting this conclusion. Concomitant with its ability to stimulate neurite outgrowth, NGF stimulated the release of APP from the hippocampal explants. As previous studies have suggested that the binding of APP to heparan sulfate proteoglycans (HSPGs) in the extracellular matrix might be an important step in the regulation of neurite outgrowth by NGF, we examined the effect of APP on neurite outgrowth from dissociated hippocampal cells cultured on various protein substrates. When cells were cultured on a substrate of APP and HSPG, neurite outgrowth was markedly stimulated. No stimulation of neurite outgrowth was seen when neurons were cultured on substrates of either APP or HSPG alone. The results suggest that secreted forms of APP may be involved in stimulating neurite outgrowth from hippocampal neurons and that interactions between APP and HSPG may be important for a neurite outgrowth‐promoting function. © 1994 Wiley‐Liss, Inc.