bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultracytochemical localization of adenylate cyclase and guanylate cyclase in crushed peripheral nerves
Authors: Rambotti Maria Grazia , Spreca Antonio , Rende Mario , Donato Rosario 
Published: January 2005

AbstractCellular and subcellular distribution of adenylate cyclase (AC) and guanylate cyclase (GC) activities in crushed peripheral nerves during regeneration were studied at the electron microscope level. In unlesioned nerves, no AC reaction product could be evidenced, whereas GC was detectable on the plasma membranes of Schwann cells, myelinated and nonmyelinated fibers, and within nonmyelinated axons. At 24 hours after the crush, AC reaction product was found within axonal segments proximal to the zone of the crush in association with mitochondria. At this stage, macrophage‐like cells, which probably are transformed Schwann cells, polymorphonuclear leucocytes, and endothelial cells displaying an intense AC reaction product could be detected. On the other hand, at 24 hours after the crush, GC was no longer detectable, except on occasional unlesioned nerve fibers. At 48 hours after the lesion, AC reaction product was no longer detectable within axons, and all AC positivity was associated with plasma membranes of non‐neuronal cells, including transformed Schwann cells, occasional macrophages, polymorphonuclear leucocytes, fibroblasts, and elongated cells. As to GC, images similar to those obtained at 24 hours were observed until 48 hours after the crush. From the 7th to the 28th postlesion day, AC activity was localized exclusively to the plasma membranes of fibroblasts and elongated cells. Transformed Schwann cells were no longer detectable, whereas normal Schwann cells and regenerating axons could be seen, and these showed no AC reaction product in analogy to the absence of AC reaction product of unlesioned nerves. During the same period, GC again was detectable on regenerating fibers with the same subcellular localization as that of unlesioned nerves. The present results strongly suggest that starting from the second postcrush day, cells invading the lesioned zone and transformed Schwann cells, all taking part in the formation of the new perineurial tissue, display a high AC activity, which should be taken into account when measuring cyclic adenosine monophosphate (cAMP) levels under these conditions. Also, our data suggest that GC is involved primarily in regeneration processes that occur in crushed peripheral nerves. Thus, the pattern of AC distribution in peripheral unlesioned and lesioned nerves appears to be exactly the opposite of the GC localization examined under similar experimental conditions insofar as nervous fibers are concerned.
Axon‐glia transfer of a protein and a carbohydrate
Authors: Grossfeld Robert M. , Klinge Maura A. , Lieberman Edward M. , Stewart Louise C. 
Published: January 2005

AbstractWe have investigated the transfer of a fluorescent protein, the fluorescein isothiocyanate derivative of bovine serum albumin (FITC‐BSA), and a fluorescent carbohydrate, FITC‐dextran, from the crayflsh medial giant axon (MGA) to the periaxonal glial cells. The dialyzed tracer was injected into one of the two MGAs, and, after a transfer period of 15–60 min, the tissue was fixed for histological examination of fluorescence distribution. With each tracer, the periaxonal sheath of the injected MGA was specifically labeled. Similar results were obtained with several different fixatives. During the transfer period, there was no appreciable change in the resting potential or conducted action potential of the MGA or in the resting potentials of the adaxonal glial cells. Polyacrylamide gel electrophoresis indicated that the axoplasmic and sheath fluorescence was produced by the intact tracers. These results suggest that “foreign” macromolecules can be exchanged from crayfish axons to glia under physiological conditions. Such transfers may indicate a substantial intercellular traffic of molecules or a means whereby neurons can eliminate waste materials.
Effect of thyroid deficiency on the development of glia in the hippocampal formation of the rat: An immunocytochemical study
Authors: Rami Abdelhaq , Rabíe Alain 
Published: January 2005

AbstractThe development of glia in the hippocampal formation of normal and hypothyroid rats was studied using immunocytochemical staining for either glial fibrillary acidic protein (GFAP) or vimentin. Light microscopy showed lower GFAP immunoreactivity in the radial glial processes of young hypothyroid rats compared to normal animals. These processes followed the known path of neuroblast migration toward the proliferative zone of the dentate gyrus until the end of the 1st postnatal week. Vimentin immunoreactivity showed that the glial processes were present and therefore immature at least with respect to their cytoskeletal composition. We propose that this early defect in the maturation of the radial glial fibers accounts for the final deficit in the granule cells of the dentate gyrus. Later in development, thyroid deficiency also reduced the density and number of GFAP‐labeled astrocytes and the growth of their processes. This observation is in complete disagreement with the glial hypertrophy induced by thyroid deficiency in the cerebellum. The considerably increased histogenetic cell death observed in the cerebellum of young hypothyroid rats could in turn induce glial hypetrophy, whereas the hippocampal formation, where a normal low number of cell deaths is observed, is only subjected to the general depressive effect of thyroid deficiency on cell maturation.
Glutamate and kainate increase intracellular sodium activity in leech neuropile glial cells
Authors: Ballanyi K. , Dörner R. , Schlue W.‐R. 
Published: January 2005

AbstractNa+‐selective, double‐barrelled microelectrodes were used to measure intracellular Na+ activity (a) and membrane potential (Em) in neuropile glial cells of isolated segmental ganglia in the leech Hirudo medicinalis. Bath application of glutamate (10−3 M) resulted in membrane depolarizations of about 5 mV and a concomitant increase of a by between 2 and 10 mM. Kainate (10−4 M) elicited depolarizations of up to 40 mV amplitude followed by a prominent afterhyperpolarization. During kainate, a increased by 7 to 25 mM. In contrast to glutamate, an initial decrease of a was detected during the action of kainate. N‐methyl‐D‐aspartate (NMDA, 10−5–10−3M) had no effect of Em and a. The results indicate that leech glial cells have a kainate‐preferring non‐NMDA glutamate receptor.
Glia:Neuron index: Review and hypothesis to account for different values in various mammals
Authors: Reichenbach Andreas 
Published: January 2005

AbstractThe present paper proposes a hypothesis to account for different values of the glia:neuron index in comparable central nervous system tissues of various mammals. This hypothesis assumes that K+ ions released by active neurons are a mitogenic signal for glial cells. The thicker the tissue (for example, the brain wall), the more difficult is efficient K+ clearance, and more perinatal glial cell proliferation should occur. Thus, this hypothesis accounts for higher glia:neuron indices in mammals with thicker brain walls.
Pharmacological identification of the α‐adrenergic receptor type which inhibits the β‐adrenergic activated adenylate cyclase system in cultured astrocytes
Authors: Northam William J. , Bedoy Cynthia A. , Mobley Philip L. 
Published: January 2005

AbstractThe adrenergic agonist norepinephrine can exert its influence on cell function by activating both α‐ and β‐adrenergic receptors. In astrocytes, the α‐adrenergic receptor activity of norepinephrine is known to inhibit the cyclic AMP response elicited by its action at β‐adrenergic receptors. Pharmacological studies were conducted to identify the subtype of α‐adrenergic receptor which mediates this inhibitory action. The α2‐adrenergic antagonist yohimbine potentiated the cyclic AMP response elicited by norepinephrine, whereas the α1‐adrenergic antagonist prazosin did not affect the response. The α2‐adrenergic agonist clonidine inhibited the cyclic AMP response elicited by the β‐adrenergic agonist isoproterenol and this inhibition could be blocked by yohimbine but not by prazosin. In contrast, the α1‐adrenergic agonist phenylephrine did not inhibit the cyclic AMP response to isoproterenol. These studies indicate that the inhibitory action of norepinephrine is mediated by its action at α2‐adrenergic receptors.
Astrocytes in cell culture incorporate GM1 ganglioside
Authors: Masco Daniel , Flott Berenike , Seifert Wilfried 
Published: January 2005

AbstractGanglioside GM1 3H‐labelled at the terminal galactose was added to astrocyte cell cultures. GM1 incorporation was studied in the two typical forms of astrocytes in cell culture of flat and stellate morphology. There was a strong time‐ and concentration‐dependent increase in GM1 incorporation for both cell types of astrocytes. The incorporation of GM1 into the stellate form increased continuously up to 48 h (maximum time studied), while the incorporation into the flat form reached a plateau at the same time. After 2 h of GM1 incubation additional gangliosides appeared; the latter resulted from the metabolism of the GM1 incorporated, indicating that astrocytes in cell culture can biosynthesize more complex gangliosides. To confirm that GM1 was indeed incorporated into astrocytes, two other different approaches were used. Astrocyte cells treated with 3H‐GM1 were visualized using autoradiography. The specific marker for GM1, rhodamine‐labelled choleratoxin, was used to detect the incorporated GM1 using fluorescence microscopy. In both cases GM1 treated cells were intensely labelled. These observations indicate that exogenous GM1 ganglioside can also be integrated into the astrocyte membranes as occurs in other types of cells and membranes.
Patterns of gliosis in alzheimer's disease and aging cerebrum
Authors: Beach T.G. , Walker R. , McGeer E.G. 
Published: January 2005

AbstractThe distribution of astrocytic gliosis in Alzheimer's disease (AD) and aging cerebrum, as marked by immunoperoxidase staining for glial fibrillary acidic protein (GFAP), was examined in whole‐hemisphere coronal sections. Cortical gliosis in AD had an obvious laminar pattern. There were two heavy bands of staining, one in layers II–III and another in layer V. Normal aging cases sometimes displayed considerable cortical gliosis, but no specific patterns were apparent. Most AD cases, and some normal aging cases, displayed hypertrophy of immunoreactive astrocytes at grey matter‐white matter interfaces, especially the cortico‐medullary junction. Subcortical grey matter gliosis was common in both normal aging and AD, but there was no consistent pattern in either group. The deep cerebral white matter, which is stained evenly and heavily in young, healthy individuals, showed uneven staining in both normal elderly and AD brains. In both AD and aging, perivascular gliosis was prominent throughout the cerebrum and especially in the putamen. In conclusion, both AD and aging cerebri show extensive gliosis: AD cortical gliosis has a specific laminar pattern, but there does not appear to be an AD‐specific pattern of subcortical gliosis.
Cell cultures enriched in oligodendrocytes from the central nervous system of trout in terms of phenotypic expression exhibit parallels with cultured rat schwann cells
Authors: Jeserich Gunnar , Rauen Thomas 
Published: January 2005

AbstractOligodendrocytes were isolated from the white matter of young trout by Percoll density centrifugation of enzymatically dissociated tissue and cultured on poly‐D‐lysine–coated petri dishes. Using antisera recognizing myelin‐specific compounds of fish CNS (36K, IP2) up to 72% of the isolated cells could be identified as oligodendrocytes with an average yield of 4 X 106 cells per gram of wet tissue. Taken in culture, the cells rapidly regenerated their processes and soon acquired a morphology closely resembling mammalian oligodendrocytes in vitro. On the other hand, in terms of phenotypic expression, interesting parallels were revealed with the known in vitro behavior of Schwann cells: Galactocerebroside, which in mammalian oligodendrocytes is persistently expressed over longer periods of time in vitro, rapidly disappeared from the surface of cultured trout oligodendrocytes. In contrast, the fish CNS myelin glycoprotein IP2, which like IP1 is immunologically related to the major myelin product of Schwann cells, Po, was continuously expressed over several weeks in culture. Two other myelin protein constituents, 36K and IP1, transiently declined in vitro, but later on fully reappeared in the glial cells of trout. The present cell culture system offers an experimental model for studying in vitro the factors underlying oligodendroglial regeneration and remyelination in the fish CNS.
Immunohistochemical localization of glutamine synthetase in mesencephalon and telencephalon of the lizard Gallotia galloti during ontogeny
Authors: Monzon‐Mayor M. , Yanes C. , Tholey G. , De Barry J. , Gombos G. 
Published: January 2005

AbstractThe immunohistochemical localization of glutamine synthetase, an astrocyte marker in mammals, was determined in the telencephalon and mesencephalon of the lizard Gallotia galloti during development by using an antiserum raised against chicken brain glutamine synthetase. Ependymal glial cells and their radial processes were glutamine synthetase immunoreactive, and they were present also in the adult. Immunoreactivity was also detected in two populations of scattered cell bodies, each preferentially localized in different zones: star‐shaped cells morphologically similar to mammalian astrocytes, and ovoid or pear‐shaped cell bodies, the processes of which were aligned with radial fibers and formed perivascular end‐feet. Both populations displayed ultrastructural characteristics of astrocytes even though a comparison with our previous results (Monzon‐Mayor et al., 1989; Yanes et al., 1989) indicated that many of these cells did not react with antibodies directed against the astrocyte‐specific glial fibrillary acidic protein.During ontogeny, glutamine synthetase immunoreactivity appeared in radial glial processes and in ependymal glial cells of midbrain at embryonic stage 35 (E35) and of telencephalon at E37; in both regions, immunoreactivity in the radial glia increased until hatching and then decreased until adulthood, but it did not disappear. Labelled scattered cells became progressively more numerous and more immunoreactive.A comparative analysis of the distribution of these cells at different ages tends to suggest that some of the “ovoid” astrocytes originate in, and migrate out from, the proliferative zone of the different sulci, whereas the star‐shaped cells appear directly in situ, probably because they begin to express glutamine synthetase after they have reached their final location.
Short‐term post‐grafting morphological alterations of glia from an adult brain transplant
Authors: Ignacio V. , Gansmuller A. , Collins V. P. , Suard I. , Jacque C. 
Published: January 2005

AbstractFragments of corpus callosum from adult rabbit have been implanted into the brain of newborn mice. Previous studies had shown that under such conditions transplant‐derived astroglial cells differentiate in the host and survive for at least 2 months. The present study was devised to clarify the fate of the differentiated astrocytes present in the adult transplant by using combined ultrastructural and immunohistochemical approaches. These mature cells are shown to degenerate and die within 2 days after the implantation. Therefore, we suggest that stem cells present in adult tissue would account for the surviving population of transplant‐derived glial cells.
Enhanced release of plasminogen activator inhibitor(s) but not of plasminogen activators by cultured rat glial cells treated with interleukin‐1
Authors: Rogister B. , Leprince P. , Delree P. , Van Damme J. , Billiau A. , Moonen G. 
Published: January 2005

AbstractAstroglial cells are known to proliferate during development of the nervous system, as well as during post‐traumatic gliosis. We have previously shown that the proliferation of cultured astrocytes can be stimulated by the urokinase‐type (uPA) of plasminogen activator (PA) and that astrocytes are able to release such uPA upon stimulation with basic fibroblast growth factor, which is known to act as a mitogen for these cells.Here we report studies on the effects of human interleukin‐1 (IL‐1) on the release of PA activity by cultured newborn rat astroglial cells. Whereas there is controversy in the literature as to whether IL‐1 stimulates multiplication of astroglial cells, we failed to observe such an effect in our system. We did observe, however, a dose‐dependent decrease in PA activity in the supernatant of the IL‐1 treated cultures. Further analysis revealed that this apparent decrease in PA release was in fact due to an increased release of plasminogen activator inhibitor (PAI). A similar IL‐1 induced increase in PAI release was also found to occur in cultures of transformed astrocytes (human glioma LN18) and in cultured Schwann cells, but not in cultures of neurons or neuronal tumour cells.Since protease inhibitors are known to possess neuritogenic properties, our results suggest that IL‐1, by its capacity to induce PAI, may promote neuritogenesis.
Increased glutamate uptake and glutamine synthetase activity in neuronal cell cultures surviving chronic hypoxia
Authors: Sher Phyllis K. , Hu Shuxian 
Published: January 2005

AbstractTo examine the neurochemical effects of chronic hypoxia on immature nervous tissue in vitro, mixed neuronal–glial cell cultures derived from fetal mice were exposed to 5% O2 for 24 or 48 h. Those cultures subjected to longer hypoxia manifested improved neuronal survival compared to those with the shorter insult, both with respect to neuronal morphology and also cell counts. Neurochemical assays were performed on living cells in situ to determine the possible basis for differential cell survival. After both exposure conditions, Ro5–4864‐displaceable benzodiazepine (BDZ) binding, reflecting nonneuronal BDZ binding sites, was either not reduced or was elevated. Although initially reduced, binding of the excitatory amino acid (EAA) glutamate was progressively increased after both insults and, within 2 days after return to normoxia, was increased relative to control values (121 and 128% of controls, P < 0.05). The most impressive neurochemical differences between the two conditions related to changes in the predominantly or exclusively glial functions of glutamate uptake and glutamine synthetase activity. In those cultures with relatively preserved neuronal morphology: 1) high affinity uptake of glutamate was elevated compared to the shorter hypoxic insult by 3 days of recovery (104 vs 70%, P < 0.001) and 2) glutamine synthetase, an enzyme localized primarily within astrocytes, was significantly elevated even when compared to absolute control values (148%, P < 0.001). These data suggest that longer periods of hypoxia may be less deleterious to neurons than shorter hypoxic events because of a time‐dependent stimulation of specific glial cell functions which relate to increased metabolism of potentially neurotoxic EAAs such as glutamate.
Patchy myelination pattern in the jimpy mouse brain: Immunohistochemical study
Authors: Lachapelle F. , Lapie P. , Gansmuller A. , Villarroya H. , Gumpel M. 
Published: January 2005

AbstractThe jimpy (jp) mutation of the mouse leads to a dramatic decrease of myelination in the hemizygous mutant central nervous system (CNS). Several descriptions based on classical histology, immunohistochemistry, and electron microscopy (EM) have demonstrated the scarcity of myelin formation in the different parts of the CNS. The immunohistochemical study presented here showed a very singular patchy pattern of myelin distribution in the different areas of the whole mutant brain. The myelin patches are randomly dispersed without bilateral symmetry, and their density and location vary from one animal to another. No reproducible pattern of myelination could be found among the population observed. This distribution has been compared with observations on young heterozygotes and wild‐type homozygotes from the same strain. A similar patchy and random distribution of myelin could be observed in heterozygotes, which present an intermediate level of myelination. This strongly suggests that a migration of precursors or immature oligodendrocytes (ODCs) from the periventricular zone followed by local multiplication of colonies of ODCs before myelination is a general feature in normal as well as pathological conditions.
Channel‐mediated and carrier‐mediated uptake of K+ into cultured ovine oligodendrocytes
Authors: Hertz L. , Soliven B. , Hertz E. , Szuchet S. , Nelson D. J. 
Published: January 2005

AbstractUptake of radioactive K+ by mature ovine oligodendrocytes (OLGs) maintained in primary culture was measured under steady‐state conditions, i.e., in cells maintained in a normal tissue culture medium (5.4 mM K+), and in cells after depletion of intracellular K+ to less than 15% of its normal value by pre‐incubation in K+‐free medium. The latter value is dominated by an active, carrier‐mediated uptake (although it may include some diffusional uptake), wheras the former, in addition to active uptake, also reflects passive K+ diffusion through ion selective channels and possible selfexchange between extracellular and intracellular K+, which may be carrier‐mediated. The total uptake rate was 144 ± 10 nmol/min/mg protein, and the uptake after K+ depletion was 60 ± 2 nmol/min/mg protein, much lower rates than previously observed in astrocytes. The uptake into K+‐depleted cells was inhibited by about 80% in the presence of ouabain (1 mM) and about 30% in the presence of furosemide (2 mM). Activators of protein kinase C (phorbol esters) and cAMP‐dependent protein kinase (forskolin) have been shown to alter the myelinogenic metabolism as well as outward K+ current in cultured OLGs. The present study demonstrates that K+ homeostasis in OLGs is modulated through similar second messenger pathways. Active uptake was inhibited by about 60% in the presence of active phorbol esters (100 nM) but was not affected by forskolin (100 nM). Forskolin likewise had no effect on total uptake, whereas phorbol esters caused a much larger inhibition than expected from their effect on carrier‐mediated uptake alone, suggesting that channel‐mediated uptake was also reduced. The relatively small difference between the carrier‐mediated and the total uptake made it difficult to assess accurately the effects of these agents on channel‐mediated uptake. Electrophysiological experiments were carried out to assess directly the inhibitory effects of these compounds on inward rectifier K+ channel (Kir+) activation. The phorbol ester, phorbol 12‐myristate 13‐acetate (1.5 to 100 nM), decreased the amplitude of the steady‐state Kir+ current at ‐120 mV by approximately 40%; however, neither the inactive analog 4‐α phorbol‐12–13 didecanoate nor forskolin (0.1 to 1 μM) decreased current amplitude when extracellular solutions contained normal K+ concentrations. It can be concluded that both the carrier‐mediated K+ uptake and passive K+ influx through inwardly rectifying K+ channels in OLGs are modulated by protein kinase C but not by cAMP‐dependent protein kinase activation. Furthermore, both carrier‐mediated and total K+ uptake in oligodendrocytes are significantly lower than that measured in astrocytes, implying differential physiological roles for astrocytes and oligodendrocytes in K+ homeostasis.