bluuebunny/crossref_metadata_2025_split huggingface dataset:
Outstations of the golgi complex are present in the processes of cultured rat oligodendrocytes
Authors: de Vries H. , Schrage C. , Hoekstra K. , Kok J. W. , van der Haar M. E. , Kalicharan D. , Liem R. S. B. , Copray J. C. V. M. , Hoekstra D. 
Published: January 2005

AbstractPrimary cultures of rat oligodendrocytes were incubated with a fluorescent sphingolipid precursor, 6‐[N‐(7‐nitrobenz‐2‐oxa‐1,3,‐diazol‐4‐yl)amino]hexanoylceramide (C6NBD‐ceramide). This compound is known to stain the Golgi complex specifically. Within 30 min of incubation at 37°C most of the C6NBD‐ceramide was incorporated into the perinuclear Golgi system, as revealed by conventional and confocal laser fluorescence microspcopy. Interestingly, C6NBD‐ceramide was found to acculmulate also in smaller, oval‐shaped structures in many of the processes, at distances up to 30 μm from the nucleus. This implies the possibility that these structures are Golgi (‐derived) complexes. Indeed, after incubation of oligodendrocytes with C6‐ceramide and rhodamine‐labeled transferrin both fluorescent labels colocalized in the Golgi system of the cell body as well as in the structres in the processes. Additional support for the Golgi character of these structures was obtained by transmission electron microscopy. Particularly in oligodendrocytes cocultured with neurons, many Golgi structures were present all over the processes. The results lead us to conclude that, in the oligodendrocyte, the Golgi complex does not only reside in the perikaryor, but also in the processes. One can speculate that a polarized biosynthetic activity, involving the presence of the Golgi near the site of myelin synthesis, may be advantageous to the oligodendrocyte for assembly and/or repair of the myelin membrane at the distal end of the processes. © 1993 Wiley‐Liss, Inc.
AMPA‐Selective glutamate receptor subunits in astroglial cultures
Authors: Condorelli D. F. , Dell'Albani P. , Corsaro M. , Barresi V. , Stella A. M. Giuffrida 
Published: January 2005

AbstractWe analysed AMPA ionotropic receptor subunits at the mRNA level (GluR‐1 to ‐4) and at the protein level (GluR‐1 and GluR‐2/3/4C) in “primary astroglial cultures” (non‐neuronal cell cultures highly enriched in glial fibrillary acidic protein [GFAP] positive cells) prepared from newborn rat cerebral hemispheres, cerebral cortex, hippocamps, and striatum and in “brain non‐neuronal cell cultures” (low percentage of GFAP positive cells) prepared from cerebellum, brainstem, mesencephalon, and hypothalamus. For comparison, we also determined ampa subunit mRNA and protein levels in different brain regions. By Northern blot analysis mRNAs for the AMPA receptor subunits (glur‐1,‐2,‐3,‐4) were detected in primary rat cerebral hemispheres astroglial cultures. Immunoblotting analysis with anti‐GluR‐1 and anti GluR‐2/3/4C polyclonal antibodies confirmed the presence of low leve of immunoreactive proteins of the same size of those identifice in vivo as GluR subunits. Expression of GluR genes varied depending on the brain area used as starting material for the preparation of the cultures: GluR‐1, ‐2, and ‐3 were mailly expressed in cortical cultures, while GluR‐4 expression predominated in brainstem derived cultures. Interestingly this pattern of expression correlates with that observed in the intact brain, where high levels of GluR‐4 mRNA and low levels of the other GluR subunits were found in the brainstem. In conclusion our results confirm the existence of glutmate ionotropic receptors of the AMPA type in primary astroglial cultrues and suggest that GluR‐4 is the main AMPA receptor subunit expressed in non neuronal cells of the central nervous system. © 1993 Wiley‐Liss, Inc.
Myelin gene activation: A glucose sensitive critical period in development
Authors: Royland J. E. , Konat G. W. , Wiggins R. C. 
Published: January 2005

AbstractGlucose deprivation was employed to model caloric undernutrition in newborn rat mixed glial cultures. Six day‐old cultures were placed in serum‐free media containing glucose concentrations from 0.55 mg/ml to 10 mg/ml. The expression of the myelin PLP, BP, and MAG genes was determined by Northern blot analysis. The activation of the myelin genes began at approximately 6 day in vitro (DIV), and a period of rapid upregulation followed through 14 DIV. The gene activity was directly related to the glucose concentrat.The increase in glucose concentration from 0.55 to 1.5 mg/ml (which spans the physiological range) resulted in 2–3 fold increases in expression of the myelin genes, whereas further increases in glucose (2–10 mg/ml) produced only slight additional elevation in the gene activity. We used high glucose (5–6 mg/ml) as control, or low glucose (0.55 mg/ml) as deprived, to delineate possible critical periods of oligodendrocytic differentiation. Cultures were deprived for 4‐day intervals, staggered from 6 to 22 DIV. Deprivation from 6 to 10 DIV produced an 80–90% suppression of the myelin gene upregulation at 22 DIV; deprivation from 10 to 14 DIV produced 60–70% suppression; whereas deprivation from 14 to 18 DIV was fully recoverable by 22 DIV. These results show that mixed glial cultures model the developmental pattern of myelin gene expression, as well as their vulnerability. Furthermore, the period of rapid upregulation of the myelin genes appears to be a critical period in development, during which glucose deprivation irreversibly alters oligodendrocyte differentiation. © 1993 Wiley‐Liss, Inc.
Temporal and spatial distribution of heat shock mRNA and protein (hsp70) in the rabbit cerebellum in response to hyperthermia
Authors: Manzerra P. , Rush S. J. , Brown I. R. 
Published: January 2005

AbstractWe have previously investigated the expression of hsp70 genes in the hyperthermic rabbit brain at the mRNA level by Northern blot and in situ hybridization procedures. Our studies have now been extended to the protein level utilizing Western blot and immunocytochemistry. Using an antibody which is specific to inducible hsp70, a prominent induction of hsp70 protein in glial cells of hyperthermic animals was noted. In particular, Bergmann glial cells in the cerebellum are strongly immunoreactive while adjacent Purkinje neurons are immunonegative. Extension of our in situ hybridization studies to a time course analysis revealed that the initial glial induction events were followed by a delayed accumulation of inducible hsp70 mRNA in Purkinje neurons at 10 hr post‐heat shock. In control animals, high levels of constitutively expressed hsc70 mRNA and protein were observed in Purkinje neurons. Similar hsc70 and hsp70 mRNA observations were also made in neurons of the deep cerebellar nuclei and in motor neurons of the spinal cord. Our results suggest that these neuronal cell types accmulate hsp70 mRNA in response to hyperthermic treatment; however, the response is delayed when compared to the rapid response seen in glial cells. The high constitutive levels of hsc70 in certain neuronal cell types may play a role in the initial dampening of the hsp70 induction response in these cells. © 1993 Wiley‐Liss, Inc.
Transferrin in the central nervous system of the shiverer mouse myelin mutant
Authors: Connor J. R. , Roskams A. J. , Menzies S. L. , Williams M. E. 
Published: January 2005

AbstractTransferrin, the iron mobilization protein, and its mRNA are normally present in oligodendrocytes. Previous reports using myelin mutants have shown both a decrease in transferrin protein and mRNA when the oligodendrocyte population is compromised. In this study the shiverer mouse mutant in which the oligodendrocyte population is numerically normal, but has both quantitatively diminished and qualitatively abnormal myelin was used. This animal model was chosen to address the question whether expression of the transferrin message and/or protein correlated more closely to the number of oligodendrocytes (normal) or the amount of myelin (abnormally low). A 1/2 to 2/3 decrease in transferrin protein occurred in all brain regions examined except for the spinal cord in the shiverer group compared to both heterozygous littermates and wild type controls. Levels of transferrin transcripts in the brain are not affected by the shiverer mutation. These results taken with previous reports from this laboratory indicate that the presence of oligodendrocytes is a requirement for normal expression of transferrin mRNA in brain but is not sufficient for normal values of the protein. The level of Tf protein correlates more closely with the amount of myelin present than it does with the numbers of oligodendrocytes present. These data are consistent with previous reports from our laboratory that transferrin accumulation by oligodendrocytes is associated with myelin production by these cells. These data further suggest transferrin mRNA may be constitutively expressed by oligodendrocytes and that the protein expression is regulated at the level of translation. © 1993 Wiley‐Liss, Inc.
Oxygen radical‐induced neurotoxicity in spinal cord neuron cultures
Authors: Michikawa M. , Lim K. T. , McLarnon J. G. , Kim S. U. 
Published: January 2005

AbstractThe neurotoxic effects of oxygen radical on spinal cord neuron cultures derived from fetal mouse have been studies. Oxygen radicals, superoxide radical and hydrogen peroxide, were generated by adding xanthine oxidase and hypoxanthine in the culture medium. Exposure of neurons to this oxygen radical generating system resulted in a significant cell death and decrease of choline acetyltransferase (ChAT) activity in a time‐dependent manner in spinal cord neuron cultures. The decrease in cell viability and ChAT enzyme activity induced by the oxygen radicals was blocked by scavengers such as superoxide dismutase (SOD), catalase, and tetrakis (2‐pyridylmethyl) ethylenediamine (TPEN), a metal chelator. Antagonista of the N‐methyl‐D‐aspartate (NMDA) receptor, including MK801 (a noncompetitive NMDA antagonist), D‐2‐amino‐5‐phosphonovaleric acid (APV) (a competitive NMDA antagonist), and 7‐chlorokynurenic acid (an antagonist at the glycine site associated with the NMDA receptor), similarly blocked oxygen radical‐induced decrease in cell viability and ChAT activity in spinal cord neuron cultures. These results indicate that both oxygen radicals and excitotoxic amino acids were involved in the oxidant‐ititiated neurotoxicity of spinal cord neurons. © 1994 Wiley‐Liss, Inc.
Autoradiographic characterization of the non‐N‐methyl‐D‐aspartate binding sites in human cerebellum using the antagonist [3H]6‐cyano‐7‐nitroquinoxaline‐2,3‐dione
Authors: Hatziefthimiou A. , Mitsacos A. , Kouvelas E. D. 
Published: January 2005

AbstractUsing quantitative autoradiography, we have characterized the binding properties of the non‐N‐methyl‐D‐aspartate (NMDA) glutamate receptor antagonist [3H]6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX) in adult human cerebellum. Saturation experiments revealed [3H]CNQX binding to a single class of sites with similar affinity in the molecular and granule cell layer (Kd = 89.0 ± 6.4 and 83.3 ± 9.9nM, respectively). The maximum number of [3H]CNQX binding sites was much higher in the molecular compared to the granule cell layer (Bmax = 16.2 ± 1.1 and 2.8 ± 0.5 pmol/mg protein, respectively). Inhibition experiments were performed in order to examine the pharmacological profile of [3H]CNQX binding in the molecular layer. [3H]CNQX labeled sites with high affinity for both non‐NMDA agonists, (RS)‐α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionic acid (AMPA) and kainate. Dose‐response curves for inhibition of [3H]CNQX by AMPA and Kainate were biphasic. The potency of AMPA for displacement of [3H]CNQX binding (Ki © 1994 Wiley‐Liss, Inc.:2.8 ± 0.8 nM and 12.5 ± 0.8 μM) was 4‐ to 6‐fold greater than the corresponding potency of kainate (Ki:18.1 ± 5.7 nm and 48.7 ± 9.3 μM). In conclusion, the pharmacological analysis of [3H]CNQX binding in the human cerebellar molecular layer reflects the existence of multiple binding sites of the non‐NMDA receptor that have different affinities for both AMPA and kainate. © 1994 Wiley‐Liss, Inc.
Isoforms of ferritin have a specific cellular distribution in the brain
Authors: Connor J. R. , Boeshore K. L. , Benkovic S. A. , Menzies S. L. 
Published: January 2005

AbstractFerritin is the major iron storage protein and accounts for the majority of the iron in the brain. Thus, ferritin is a key component in protecting the brain from iron induced oxidative damage. The high lipid content, high rate of oxidative metabolism, and high iron content combine to make the brain the organ most susceptible to oxidative stress. The role of oxidative damage and disruption of brain iron homeostasis is considered clinically important to normal aging and a potential pathogenic component of a number of neurologic disorders including Alzheimer's disease and Parkinson's disease. Little is known, however, of the mechanism by which the brain maintains iron homeostasis at either the whole organ or cellular level. In this study we report the cellular distribution of the two isoforms of ferritin in the brain of adult subhuman primates. A subset of neurons immunolabel specifically for the H‐chain ferritin protein, whereas cells resembling microglia are immunolabeled only after exposure to the L‐chain ferritin antibody. Only one cell type immunostains for both H‐and L‐chain ferritin; these cells are morphologically similar and have the same distribution pattern as oligodendrocytes. Neither ferritin isoform is usually detected in astrocytes. These data indicate considerable differences in iron sequestration and use between neurons and glia and among neuronal and glial subtypes. This information will be essential in determining the role of each of these cells in maintaining general brain iron homeostasis and the relative abilities of these cells to withstand oxidative stress. © 1994 Wiley‐Liss, Inc.
Phosphorylation of neurofilament H subunit as related to arrangement of neurofilaments
Authors: Gotow T. , Tanaka J. 
Published: January 2005

AbstractTo find out what causes differences in phosphorylation states in neurofilaments (NF), we selected two types of dendrite, one provided with very few NFs (Purkinje cell) and the other with relatively many (anterior horn cell). We examined these with four monoclonal antibodies selected by the Western blot analysis, two (NE14 and SMI31) recongnizing only phosphorylated, SMI32 recognizing only nonphosphorylated, and N52 recognizing phosphorylation‐independent epitopes of NF‐H. The immunoperoxidase labeling of dendrites, and also of perikarya, in both neurons was detectable with all four antibodies. After the tissue was treated with Triton X‐100, the labeling was still detectable with SMI32 or N52, but undetectable with NE14 and SMI31. The brain homogenate Triton‐extracted supernatant after centrifugation at 100,000g for 1 hr showed the staining of NE14, SMI31, and N52 but not that of SMI32. In Purkinje cell dendrite and perikaryon, NFs always appeared singly. In the immunogold labeling, they were labeled only with SMI32 or N52. Labeling by NE14 or SMI31 was distributed throughout the cytoplasm and hardly associated with NFs. In the anterior horn cell dendrite and perikaryon, NFs appeared both single and in bundles. They were predominantly labeled with SMI31 or N52 when they were single, and with NE14, SMI31, or N52 when they were bundled. Even in one NF, portions that appeared single were labeled mostly with SMI32 or N52, while the remainder, to which other NFs approached closely, were labeled mostly with NE14, SMI31, or N52. Thus, when NFs appear singly, NF‐H in their projections or cross‐bridges with other organelles is not phosphorylated, while when NFs are bundled, NF‐H is phosphorylated in crossbridges between NF core filaments. These data may explain why the NF‐H is heavily phosphorylated in axons, where NFs are abundant, and not in dendrites and perikarya, where NFs are sparse. Wiley‐Liss, Inc.
Induction of heat shock (stress) protein 70 and its mRNA in the normal and light‐damaged rat retina after whole body hyperthermia
Authors: Tytell M. , Barbe M. F. , Brown I. R. 
Published: January 2005

AbstractIn situ hybridization and immunocytochemistry were used to investigate the distribution of the 70 kDa heat shock or stress protein (hsp70) and its mRNA in specific layers of the retina of adult rats at 0, 4, 18, and 48 or 50 hr after a brief whole body hyperthermic treatment. Induction of hsp70 mRNA was noted in the photoreceptor layer of the retina within 4 hr after hyperthermia. Pronounced accumulation of inducible hsp70 immunoreactivity was observed in cytoplasmic extensions of the photoreceptor cells, especially the inner segment zone which attained peak levels at the 18 hr time point. Selective destruction of photoreceptors by light damage prior to hyperthermia inhibited the post‐hyperthermic rise in newly synthesized retinal hsp70. Our results suggest that the photoreceptor cell layer is the primary site of synthesis of hsp70 in the rat retina and that the greatest increase in hsp70 immunoreactivity following such a hyperthermic stress occurs in that layer. This stress response of the photoreceptors is discussed in relation to their location and function in the retina. © 1994 Wiley‐Liss, Inc.
Dibutyryl cAMP, interleukin‐1β, and macrophage conditioned medium enhance the ability of astrocytes to promote neurite growth
Authors: Miller C. , Tsatas O. , David S. 
Published: January 2005

AbstractAstrocytes purified from the neonatal rat brain were cultured for up to 3 weeks prior to being treated with agents that can induce reactive changes in astrocytes. These agents included dibutyryl cAMP, interleukin‐1β, and macrophage conditioned media. After treating astrocytes for 3 days, the agents were removed and the ability of the astrocytes to support neurite growth was assessed by plating neonatal rat cerebellar cortical neurons. All the agents increased the ability of astrocytes to support the growth of long neurites. This was particularly evident with astrocytes treated with dibutyryl cAMP and LPS macrophageconditioned medium. These results provide direct evidence that the reactive changes induced in astrocytes in this in vitro model might aid the growth of neurites. Similar changes may underlie the injury‐induced axonal sprouting that occurs in vivo. © 1994 Wiley‐Liss, Inc.
Actin‐Binding protein, drebrin, accumulates in submembranous regions in parallel with neuronal differentiation
Authors: Asada H. , Uyemura K. , Shirao T. 
Published: January 2005

AbstractDrebrins are developmentally regulated actin‐binding proteins. In this study, we analyzed subcellular distribution of drebrin E in neuroblastoma cells (SHSY5Y) in culture, especially in terms of its relationship to actin filaments. In undifferentiated cells, drebrin E was scattered as flocculus small dots along the stress fibers and also accumulated at adhesion plaques. In parallel with the neuronal differentiation following retinoic acid treatment, drebrin E was accumulated, accompanying filamentous (F) actin, in the submembranous cortical cytoplasm. Similar submembranous localization of drebrins was observed in primary cultured neurons. In the presence of drebrin E F‐actin was more stable against cytochalasin D than F‐actin lacking drebrin E. These results suggest that drebrin E plays a role in neuronal morphological differentiation by changing its subcellular localization with stabilized F‐actin. © 1994 Wiley‐Liss, Inc.
Effect of L‐glutamic acid on acid secretion and immunohistochemical localization of glutamatergic neurons in the rat stomach
Authors: Tsai L. H. , Tsai W. , Wu J.‐Y. 
Published: January 2005

AbstractGlutamatergic neurons in the rat stomach were localized immunohistochemically using antibodies against L‐glutamate (L‐Glu) as well as glutamate synthesizing enzyme, glutaminase (GLNase). Myenteric ganglia and nerve bundles in the circular muscle and the longitudinal muscle were found to contain GLU‐ and GLNase‐positive nerve fibers, while submucosa and mucosa were devoid of glutamatergic innervation. The distribution of glutamatergic neurons and their processes in both myenteric ganglia and circular muscle is heterogeneous within the stomach. The effect of L‐Glu on gastric acid secretion was investigated on an everted preparation of isolated rat stomach. L‐Glu at 10−7 and 10−8 M alone had no effect on acid secretion. It was found that the oxotremorine‐, histamine‐, or gastrin‐stimulated acid secretion was markedly reduced by L‐Glu at 10−8 M, whereas L‐Glu had little effect on the acid secretion stimulated by dimethyl‐phenylpiperazinium (DMPP) at this concentration. However, at higher concentration, e.g., 10−7 M, L‐Glu also markedly reduced DMPP‐induced acid secretion. Among L‐Glu receptor agonists tested, quisqualic acid (QA) is most potent, followed by kainic acid (KA) and N‐methyl‐D‐aspartic acid (NMDA) in inhibiting oxotremorine‐stimulated acid secretion. Furthermore, this inhibitory effect of L‐Glu on oxotremorine‐stimulated acid secretion is blocked by 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX), a specific non‐NMDA receptor antagonist.All these results suggest that glutamatergic neurons are involved in the modulation of gastric acid secretion via ionotropic QA/KA receptors, probably through openings of Ca2+ channels. © 1994 Wiley‐Liss, Inc.
Monoamine‐activated α2‐macroglobulin inhibits choline acetyltransferase of embryonic basal forebrain neurons and reversal of the inhibition by NGF and BDNF but not NT‐3
Authors: Liebl D. J. , Koo P. H. 
Published: January 2005

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 factors in the nervous system. © 1994 Wiley‐Liss, Inc.