bluuebunny/crossref_metadata_2025 huggingface dataset:
Interactions between amino acid neurotransmitters and flurazepam in the neocortex of unanesthetized rats
Authors: Tancredi V. , Frank C. , Brancati A. , Avoli M. , White P.
Published: January 2005

The effects induced by the benzodiazepine flurazepam (FLU) upon neuronal responses to glutamic acid (GLUT), γ‐aminobutyric acid (GABA), and glycine (GLY) were studied in the cortex of unanesthetized rats using single‐unit extracellular recordings in conjunction with iontophoretic techniques. The application of FLU (5‐20 nA) did not affect excitatory responses to GLUT, but the spontaneous firing rate was depressed by equivalent doses of this benzodiazepine. A selective increase of GABA, but not of GLY‐induced responses was seen when either low currents (5–10 nA) of FLU or GLUT driving currents were used to study the neuronal responses of the inhibitory amino acids upon steady neuronal firing. Our data demonstrate that in unanesthetized animals FLU does not affect GLUT‐ induced effects while it selectively increases GABA‐mediated inhibition.
Increased phosphorylation of nuclear protein in myonuclei isolated from denervated skeletal muscle
Authors: Held Irene R.
Published: January 2005

The slow‐twitch soleus muscle of the rat hindlimb was denervated by cutting the sciatic nerve in the midthigh on one side. A sham operation was performed on the contralateral side to provide a control soleus muscle. At 24, 48, 72, and 120 hours after these surgical procedures, the animals were sacrificed and the nuclei which were isolated from these muscles incubated in a phosphorylating medium containing [γ32P]ATP. At the 48 hour denervation period only, the in vitro phosphorylation of TCA‐precipitable nuclear proteins was significantly increased compared to control values. Resolution of the SDS‐solubilized nuclear proteins by polyacry‐lamide gel electrophoresis revealed that the increased phosphorylation was more marked in some phosphoproteins than others. The significance of these early denervation changes are discussed with respect to increases in the activities of the nuclear RNA polymerases and changes in the phosphorylation of cytosolic protein.
Regional difference in density of monoamine‐accumulating cells of carp and catfish retinas
Authors: Negishi K. , Teranishi T. , Hidaka S. , Hida S. , Naka K.‐I
Published: January 2005

By means of a histofluorescence technique, a comparative study was conducted on the regional density of dopaminergic (DA) and indoleamine‐accumulating (IA) cells in carp (Cyprinus carpio) and catfish (Ictaluruspunctatus) retinas. In order to enhance detection of fluorescent cells, noradrenaline (NA; 5.0 μg) or a mixture of NA (2.5 μg) and 5,6‐dihydroxytryptamine (5,6‐DHT; 2.5 μg) was intravitreally injected into the eyes 2–3 hr before enucleation. DA and IA cells were counted systematically in space on flat‐mounted preparations. Both classes of cells were found to be distributed similarly in the two species of fish; the cell density is highest in the circumferential margin of the retina, and is slightly higher in a region dorsal to the optic disc than in the surrounding area. Differences in the distribution pattern of the cells between carp and catfish retinas were as follows: (a) the DA cell density is higher over the whole retinal field in carp (the mean density ± SD = 34 ± 16 cells/mm2) than in catfish (13 ± 7 cells/mm2); (b) the region where the density is slightly higher than in the surrounding area is restricted to a small area immediately dorsolateral to the optic disc in carp, while it is relatively broadly placed dorsal to the optic discs, forming a horizontal band in catfish; (c) the density ratio of DA cells to IA cells is 1:l in carp but 1:2 in catfish; and (d) catfish DA cells seem to be more irregular than carp DA cells in shape, size, dendritic arborization, uptake preference for monoamines intravitreally injected, and also in depth location seen in radial cryosections.
Metabolism of cadaverine and pipecolic acid in brain and other organs of the mouse
Authors: Nomura Y. , Schmidt‐Glenewinkel T. , Giacobini E. , Ortiz J.
Published: January 2005

Cadaverine and pipecolic acid metabolism was investigated in vitro in several organs of the mouse by measuring14CO2formation from labeled precursors. The liver showed the highest formation of14C02from [ 1,5‐14C]‐cadaverine, whereas brain demonstrated a much lower formation. Anaerobiosis or inhibition of monoamineoxidase (MAO) activity significantly reduced14C02formation in every organ, but inhibition of diamine oxidase (DAO) activity had no effect in brain and kidney. Piperidine was formed from cadaverine in vitro only in the large intestine and its content. This formation is probably of bacterial origin. Under a variety of experimental conditions we were unable to demonstrate any formation of piperidine in brain from cadaverine. Biosynthesis in vitro of [3H]‐piperidine from D, L‐ [3H]‐pipecolic acid was very low in brain and kidney. With the exception of brain and kidney, no other organs showed any formation of [3H]‐piperidine. Neither MAO nor DAO inhibition influenced [3H]‐piperidine formation in the large intestine with its content. Following 1 hr incubation at 37°C under aerobic conditions, the levels of [14C]‐pipecolic acid and [3H]‐piperidine recovered from mouse brain homogenate did not indicate any significant degradation of these two substances. Our results suggest that under in vitro conditions, cadaverine is not a precursor of piperidine in brain, liver, heart, and kidney and that only very low levels of piperidine can be formed from pipecolic acid in brain. Out side the brain, formation of piperidine from pipecolic acid is detectable only in kidney and in the content of the large intestine. The latter is probably of bacterial origin. Our results do not support previous findings from other authors on an endogenous origin of piperidine in brain from cadaverine and pipecolic acid, and they suggest that (a) cadaverine is not a precursor of piperidine in brain, (b) the conversion of pipecolic acid into piperidine in the brain does not constitute a major metabolic pathway, and (c) the main source of piperidine in the CNS may be of nonneural origin.
Axonal transport of glycerophospholipids in regenerating sciatic nerve of the rat during aging
Authors: Alberghina Mario , Viola M. , Moschella F. , Giuffrida A. M.
Published: January 2005

The effect of age upon the axoplasmic transport of glycerophospholipids has been studied using as a model the regenerating sciatic nerve of young (2‐month‐old), young adult (6‐month‐old), middle‐aged (16‐month‐old), and aged (20‐month‐old) male rats. The right sciatic nerve was crushed 0.5 mm down the incisura ischiadica. Four and nine days after the lesion, a mixture of [2‐3H] glycerol and [methyl‐14C] choline was bilaterally injected into the spinal cord, at a level of the L4‐L5 vertebrae. The animals were killed 18 hr after the isotope injection. Proximal and distal portions of crushed nerve and of contralateral sham‐operated ones were dissected and consecutive 5‐mm segments were subjected to lipid extraction and analysis.

The findings of the present study are summarized as follows: (1) The accumulation of labeled lipid material axonally transported four days after nerve injury was mainly located at the crush site in young, young adult, middle‐aged, and aged rats. The accumulation of both 3H‐glycerolipids and 14C‐choline phospholipids in postcrush segments was markedly higher for young and young adult than for aged rats, four and nine days after crush; (2) the average rate of axonal regeneration, determined between days 4 and 9 following crush injury was 3.6 and 4.2 mm/day for 2‐month‐old and 6‐month‐old rats, respectively; it decreased to the value of 2.5 mm/day for 16–20‐month‐old rats.
Glial endocytosis of protein in the traumatized brain
Authors: Trachtenberg Michael C.
Published: January 2005

The effect of trauma on the clearance of exogenous protein from the extracellular space of the brain was examined in monkeys and rats. Manual contusion of the monkey temporal lobe or air puff contusion of the rat parietal cortex resulted in intense glial uptake of the protein marker, horseradish peroxidase (HRP). There was no evidence of punctate or diffuse material in neurons at or distant from the trauma site. Cellular uptake was evident as early as 4 hr post trauma and reached maximal expression 24 hr post injury. By 72 hr post trauma few labeled cells could be seen. The extent of the glial uptake of protein was suggested by the decrease in extracellular marker in the vicinity of the labeled cells and by calculation of the fraction of glia so labeled. Sites of labeled glia were highly localized, corresponding to regions of stress. The corpus callosum was most clearly labeled in the rat experiments. The data suggest that in cases of traumatic injury to the brain, glia may be selectively stimulated to pronounced uptake of protein marker and thus may represent a potential means of clearing the extracellular space of extravasated serum protein.
The site of the integration of muscular activity and respiration
Authors: Hoff H. E. , Schuhmann R. E. , Coles S. K.
Published: January 2005

Acutely decerebrate (midcollicular) cats do not, or rarely if ever, walk spontaneously; nor do they show phasic movements of progression. After low thoracic cordotomy in a Schiff‐Sherrington preparation with enhanced forelimb rigidity, appproximately 50% of the preparations begin to show spontaneous locomotory movements in the forelimbs. In some cases these movements are in periodic bursts, and at these times are associated with waxing hyperpnea beginning before the onset of the forelimb movements. This indicates the presence of an intrinsic exercise hyperpnea mechanism mediated within the central nervous system in centers caudal to the hypothalamus.
Effect of proteolysis on the activity of the sodium channel in isolated lobster nerve membrane
Authors: Barnola Flor V. , Torres M. E.
Published: January 2005

The effect of emymatic proteolysis on structural and functional properties of the isolated lobster nerve membrane was investigated. The membranes were treated with diffcrcnt amounts of either trypsin or unspecific protease. Sodium channel activity was determined by measuring the veratridine‐tetrodotoxin‐sensitive sodium influx in proteoliposomes prepared with nerve membrane and soybean lipids. The changes in the membrane proteins were followed by electrophoresis in polyacrylamide gradient gels. From the densitometric scan of the gels the relative area for each protein was obtained, and the ratio of enzyme‐treated to control areas was evaluated. Under a similar degree of proteolysis catalyzed either by trypsin or by unspecific protease, the sensitive sodium influx is not affected by trypsin, whereas it is about 60% diminshed by the unspecific protease. In this condition thc zoncs corresponding to molecular weights of 240,000 and 166,000 daltons appear modified in the electrophoretic gels by both enzymes. The 117,000‐dalton range is modified only by the unspecific proteasc. Increasing trypsin concentration diminishes sodium influx about 60%; and the 240,000‐, 166,000‐, and 117,000‐dalton zoncs appear modified. A further increase of the protease concentration totally abolishes the sensitive sodium influx and modifies practically all of the membrane proteins. The present results indicate the rathcr high sensitivity of thc mcmbranc sodium channel activity to proteolytic action, and show that the membrane sites that respond to veratridine appear to be highly affected by proteolysis. In contrast, the tetrodotoxin receptor retains its binding capacity even after treatment of the membrane with proteasc conccntrations 1,000 times higher than those affecting the sensitive sodium influx [Benzcr and Raftery, 1972; Villegas et al, 1973].
Taurine, hypotaurine, and GABA uptake by cultured neuroblastoma cells
Authors: Holopainen I. , Kontro P. , Frey H. J. , Oja S. S.
Published: January 2005

Uptake of [3H]taurine, [3S]hypotaurine, and [3H]γ‐arninobutyric acid (GABA) was studied in ncuroblastoma C 1300 cells in Krebs‐Ringer‐Hepes‐glucose medium (pH 7.4). The uptakes consisted of nonsaturable penetration (taurine and hypotaurine) and two saturable transport components: high affinity for taurine, hypotaurine, and GABA and low affinity for hypotaurine and GABA. The affinity of the high‐affinity uptake was highest for hypotaurine but the transport capacity was greatest for taurine. GABA uptake was almost abolished by taurine and hypotaurine. Hypotaurine also strongly inhibited taurine uptake, whereas GABA had only a moderate inhibitory effect on taurine and hypotaurine uptakes. The mutual inhibition suggests that these amino acids use the same transport sites when entering the cells.
Rat cortex synaptic and nonsynaptic mitochondria: Enzymatic characterization and pharmacological effects of naftidrofuryl
Authors: Dagani F. , Gorini A. , Polgatti M. , Villa R. F. , Benzi G.
Published: January 2005

In order to investigate the in vivo pharmacological effects of the drug naftidrofuryl, we prepared populations of synaptic and nonsynaptic mitochondria from rat brain cortex. In these different mitochondrial populations the activities of citrate synthase, malate dehydrogenase, total NADH cytochrome c reductase, cytochrome oxidase, and glutamate dehydrogenase were evaluated. Except for glutamate dehydrogenase, the specific activities of the enzymes evaluated in the „free”︁ mitochondrial fraction were higher than those observed in the „synaptic”︁ SM1 and SM2 mitochondrial fractions, the difference between SM1 and SM2 fractions being significant. The in vivo administration of naftidrofuryl induced few and different changes in the various mitochondrial populations.
Interaction of catecholamine‐derived alkaloids with central neurotransmitter receptors
Authors: Nimit Y. , Schulze I. , Cashaw J. L. , Ruchirawat S. , Davis V. E.
Published: January 2005

Catecholamine‐derived alkaloids of the simple tetrahydroisoquinoline, 1‐benzyltetrahydroisoquinoline and tetrahydroprotoberberine classes have been tested for their ability to inhibit the binding of seven different radioligands to neurotransmitter receptors of brain synaptic membranes. Alkaloids of all three classes were active in inhibiting 3H‐clonidine binding to α2‐adrenergic receptors. Stereoselectivity of tetrahydropapaveroline in binding to α2‐adrenergic receptors was evidenced by the marked activity of the S‐(—) isomer (IC50 = 0.65 m̈M) in comparison to the R‐(+) enantiomer (IC50 = 50 m̈M). The simple tetrahydroisoquinolines (3,4‐dihydroxytetrahydroisoquinoline and salsolinol), the four isomeric mono‐0‐methyl derivatives of 2,3,10,11‐tetrahydroxyberbine and tetrahydropapaveroline were the most potent inhibitors of 30H‐apomorphine binding to dopaminergic receptor agonist sites. The tetrahydroprotoberberines, as a class, were the most potent inhibitors of 3H‐spiroperidol binding to dopaminergic receptor antagonist sites and of 3H‐WB‐4101 binding to α1‐adrenergic receptors. The 1‐benzyltetrahydroisoquinolines exhibited varying degrees of interaction with β1‐adrenergic receptors. Tetrahydropapaveroline (IC50 = 0.3 m̈M) was the most active of the 24 alkaloids tested in inhibiting binding of 3H‐dihydroalprenolol to β1‐adrenergic receptors. None of the alkaloids significantly affected 3H‐QNB binding to muscarinic‐cholinergic receptors, and selected alkaloids from each class interacted only moderately with serotonergic receptors.
Investigations on myelination in vitro: IV. „Myelin‐Like”︁ or Premyelin Structures in Cultures of Dissociated Brain Cells From 14–15‐Day‐Old Embryonic Mice
Authors: Sarliève L. L. , Fabre M. , Susz J. , Matthieu J. M.
Published: January 2005

The present study reports ultrastructural and biochemical data characteristic of myelin‐related structures in 30‐ to 41‐day‐old cultures of dissociated brain cells from 14‐ to 15‐day‐old embryonic mice. Multilayered membranous material was identified and displayed an alternation of electron‐lucent and electron‐dense lamellae with a periodicity of 102 Å. In these membranes, typical myelin constituents like basic protein, cerebrosides, sulfatides, and CNPase could be identified. Although we are still unable to distinguish if these membranes are premyelin or compact myelin, which could be partly degraded, these results indicate that cultured mouse brain cells retain, to a certain extent, potential to produce myelinrelated membranes.
Differential effects of interferon on ventromedial hypothalamus and dorsal hippocampus
Authors: Prieto‐Gomez B. , Reyes‐Vazquez C. , Dafny N.
Published: January 2005

Three incremental doses of recombinant α‐interferon (IF) were applied iontophoretically to hippocampal and hypothalamic cells. IF produced a dose‐dependent long‐lasting excitation in hippocampal neurons, whereas, in the hypothalamus α‐IF elicited biphasic responses. The highest IF currents induced changes in the amplitude of the action potentials on both structures. Our observations suggest that IF could have a selective effect on the specific areas studied.
Protective effect of taurine and zinc on peroxidation‐induced damage in photoreceptor outer segments
Authors: Pasantes‐Morales H. , Cruz C.
Published: January 2005

Exposure of isolated frog rod outer segments (ROS) to ferrous sulfate in a Krebsbicarbonate medium causes a time‐dependent disruption of the membrane organization of the discs. Ferrous sulfate also causes ROS swelling and aggregation. Addition of taurine (5–20 mM) and zinc sulfate (250 μM) to the incubation medium markedly protected ROS from the disrupting effect of ferrous sulfate. Of other amino acids tested, only β‐alanine had a protective effect on ROS structure. Ferrous sulfate caused an increase in lipid peroxidation, measured by malonaldehyde formation. The protective effect of taurine and zinc is not accompanied by a reduction of lipid peroxidation. Water accumulation occurs as a consequence of the peroxidative action of ferrous sulfate, and this effect was counteracted by taurine and zinc. Ferrous sulfate did not cause damage to ROS structure when incubation was carried out in sucrose‐HEPES. Sodium, chloride, and bicarbonate ions caused ferrous sulfate to disrupt ROS structure. It is concluded that taurine and zinc protect ROS membranes from ion and/or water entry occurring as a consequence of membrane lipid peroxidation.
Production and characterization of monoclonal antibodies to the myelin glycolipid sulfatide
Authors: Hofstetter W. , Bologa L. , Wetterwald A. , Z'graggen A. , Blaser K. , Herschkowitz N.
Published: January 2005

Sulfatide is enriched in the myelin sheath and accounts for 5% of the total lipids in this membrane. In the present work we describe the production and characterization of mouse monoclonal antibodies against sulfatide. The antibodies were detected and characterized in a previously described ELISA test system.

The clone AIC3IA2 produced antibodies of the IgG3 class with high specificity for sulfatide. These antibodies showed almost no cross‐reactivity with galactocerebroside or with any of the other lipids we tested. When used with the peroxidase antiperoxidase technique the antibodies stained a cell population either in fixed or unfixed brain cell cultures, indicating a surface localization of sulfatide in the respective cell population. In double‐staining experiments the stained cell population was identified as myelin basic protein‐positive oligodendrocytes.
An SEM examination of granule cell migration in the mouse cerebellum
Authors: Grovas A. C. , O'Shea K. S.
Published: January 2005

The inward migration of external granule cells (EGC) from the pial surface of the developing cerebellum to from the (internal) granule cell layer was examined using SEM. Cerebella from male mice ranging in age from days 1–20 were fixed, then fractured through the developing pyramid region.

EGC were initially unspecialized cells, forming 2–3 layers at the pial surface. EGC layers increased to 6–8, granule cells in the deeper regions elongated, and a prominent space formed between superficial and deep (premigratory) strata. During peak migration (days 8–12), nests of 4–6 EGC were associated with Bergmann glial fibers (BF) of the Golgi epithelial cells, which crossed molecular and EGC layers to terminate as spiny endfeet at the pial surface. Fibrils of extracellular material (ECM) often linked both premigratory and migrating EGC with a nearby BF. The molecular layer thickened considerably and the parallel fibers were traversed by an increasing number of Bergmann fibers and Purkinje cell processes during this period. As active migration slowed (days 13–20) and EGC reached their destination below the Purkinje cell layer, they lost their polarity and were enmeshed in ECM.

The role of the Bergmann fibers and extracellular material in granule cell migration is considered.
Inhibition in corticotrophin and corticosterone secretion following photic stimulation in rats with 6‐hydroxydopamine injection into the medial forebrain bundle
Authors: Feldman S. , Melamed E. , Conforti N. , Weidenfeld J.
Published: January 2005

Changes in corticotrophin (ACTH) and corticosterone (CS) serum levels, were examined in rats in which either 6‐hydroxydopamine or vehicle were injected into the medial forebrain bundle (MFB) and which were sacrificed by decapitation 14 days later. The injection of the neurotoxin, which depleted very significantly the norepinephrine (NE) content of the mediobasal hypothalamus, elevated significantly the basal levels of serum ACTH and CS, but inhibited the rise in the levels of these hormones following photic stimulation. These results would suggest that the hypothalamic NE system has normally an inhibitory effect on basal ACTH and CS secretion and that the hormonal response to photic stimulation is mediated by that system and possibly by NE MFB fibers.
Cytosolic gangliosides of rat brain: Their fractionation into protein‐bound complexes of different ganglioside compositions
Authors: Sonnino S. , Ghidoni R. , Fiorilli A. , Venerando B. , Tettamanti G.
Published: January 2005

The sialic acid moiety of rat brain cytosolic gangliosides was radiolabeled by intracranial injection of N‐(3H)acetylmannosamine. Upon ammonium sulphate fractionation, Sepharose 6B gel filtration, and hydroxylapatite‐cellulose chromatography, ganglioside‐bound radioactivity of brain cytosolic extract followed the behavior of protein and not that of purified gangliosides. This indicates that cytosolic gangliosides occur as ganglioside‐protein complexes.

By application of hydroxylapatite‐cellulose column chromatography, fractions were obtained having different ganglioside composition. In particular, one fraction contained GM1, one GD1a, and one GT1b with a ganglioside homogeneity better than 95% in each fraction. This indicates the occurrence in brain cytosol of a GM1‐protein complex, a GD1a‐protein complex, and a GT1b‐protein complex.
Gangliosides of human spinal cord: Aberrant composition of cords from patients with amyotrophic lateral sclerosis
Authors: Dawson G. , Stefansson K.
Published: January 2005

The ganglioside content of formalin‐fixed human spinal cords and fresh human spinal cords was found to be both quantitatively and qualitatively similar. However, the spinal cord was found to be heterogeneous with respect to ganglioside content. In particular, a gradient of GD1a was observed, increasing from a low content in the cervical region to a relatively high content in the sacral region. Comparison of the ganglioside content of nine normal spinal cords and nine spinal cords from clinically diagnosed amyotrophic lateral sclerosis (ALS) patients revealed no major quantitative differences, but the unique presence of three additional gangliosides in ALS spinal cords. One of these was tentatively identified as sialosylglobotetraosylceramide and was absent from eight of nine control spinal cord samples, the sole exception being the cord from a 97‐year‐old female.
Differential expression of gangliosides on the surfaces of myelinated nerve fibers
Authors: Ganser A. L. , Kirschner D. A.
Published: January 2005

The binding of cholera and tetanus toxins to receptors on the surfaces of teased nerve fibers was used to localize GM1 and G1b‐series gangliosides, respectively, by immunocytochemical methods. Native fibers and fibers treated with various hydrolytic enzymes to degrade specific surface components were studied. With native fibers, both toxins bound abundantly to nodes of Ranvier and poorly to the most external, internodal Schwann cell surfaces. Treatment of the fibers with proteases, hyaluronidase, and chondroitin ABC lyase neither eliminated receptors at the nodes nor unmasked receptors over the internodes. The axolemma underlying the paranodal or internodal myelin, exposed by extensive treatment with protease, bound both toxins in large amounts. Neuraminidase action induced cholera toxin receptors on the Schwann cell surface; these receptors were insensitive to protease. The results indicate that GM1 and G1b‐series gangliosides are predominantly localized to axonal and glial structures of the node of Ranvier and to paranodal/internodal axolemma, and that polysialogangliosides not of the G1b‐series are present on the internodal Schwann cell surface.
Biosynthesis of gangliosides in the developing chick embryo retina
Authors: Cortassa S. , Panzetta P. , Maccioni H. J. F.
Published: January 2005

Chick embryo retinas were cultured with [3H]glucosamine on each day between days 6 and 12 of development. The total labeling of gangliosides decreased from day 6 to day 12. The decrease was mostly due to the decrease in the labeling of disialosyllactosylceramide (GD3), which diminished to less than 2%, while the labeling of the disialoganglioside GD1a decreased to about 30%. Labeling of endogenous gangliosides by incubating retina homogenates with CMP‐[3H]N‐acetylneuraminic acid, in addition to showing a decrease in the labeling of GD3, showed a twofold increase in the labeling of GD1a. The changes in the pattern of labeling correlated with the decrease of both the incorporation of [3H]thymidine into DNA and the activity of CMP‐NeuAc:GM3 sialosyltransferase and with the increase of both the activities of UDP‐Ga1NAc:GM3 N‐acetylgalactosaminyltransferase and choline acetyltransferase. The results suggest that the shift in the pattern of labeling of gangliosides occurs in association with the transition from the proliferative to the nonproliferative state of neuronal cells.

Retinas at each age cultured with [3H]glucosamine for 22 hr maintain the radioactivity in gangliosides for at least 4 additional days in culture. This indicates that within this developmental interval there is not a period characterized by having a high turnover rate of gangliosides.
Dorsal root ganglia and nerve growth factor: A model for understanding the mechanism of GM1 effects on neuronal repair
Authors: Leon A. , Benvegnù D. , Toso R. Dal , Presti D. , Facci L. , Giorgi O. , Toffano G.
Published: January 2005

The experimental strategy of adding monosialoganglioside GM1 to a culture medium of fetal chick dorsal root ganglia (DRG) was utilized as a model system in which to examine the potential role of GM1 in modulation of neuronal cell responsiveness to nerve growth factor (NGF). Data indicate that the addition of GM1 to DRG explants or to DRG dissociated neuronal cells in culture enhances NGF‐induced neurite outgrowth, neurite complexity, and neuronal cell survival following NGF withdrawal. The GM1 molecule apparently facilitates the acquisition or maintenance of the NGF‐induced specific neuronal properties. Results are consistent with the hypothesis that the presence of GM1 molecules on the neuronal cell surface, either endogenous or following stable insertion of exogenous molecules, plays a prominent role in the modulation of functional neuronal cell behavior in response to varying neuronotrophic signals. This may prove to be relevant for the comprehension of GM1 effects on the facilitation of central nervous system repair processes.
Tryptophan fluorescence properties of cholera toxin upon interacting with ganglioside GD1b
Authors: Mestrallet M. G. , Bennun F. R. , Maggio B. , Cumar F. A.
Published: January 2005

A blue shift of the tryptophan fluorescence emission spectra of cholera toxin or the B protomer is induced by disialoganglioside GD1b with a capacity similar to that of monosialoganglioside GM1. Both gangliosides were also capable of decreasing or reversing the fluorescence quenching by iodide ion of the toxin. The quenching constants (Ksv) for the toxin fluorescence in absence of gangliosides was 2.8 M−1; in presence of GM1 or GD1b, Ksv was 0.8 M−1 and 0.7 M−1, respectively. Gangliosides GD1a and GT1b were unable to decrease the quenching effect. The results suggest that GD1b induces a perturbation in the tryptophan environment of the toxin molecule similar to that induced by GM1.
Effects of ganglioside treatments on lesion‐induced behavioral impairments and sprouting in the CNS
Authors: Fass B. , Ramirez J. J.
Published: January 2005

Recent findings suggest that exogenous gangliosides improve recovery of a learned behavior (alternation in a T‐maze) which is thought to be related to sprouting after lesions of the entorhinal cortex. In the present investigation, we studied an unlearned behavior (the open‐field hyperactivity resulting from bilateral entorhinal lesions) to evaluate whether ganglioside treatments reduce the severity of initial postlesion impairments or improve recovery. We also examined whether the treatments enhance the sprouting of septodentate fibers which parallels the recovery of open‐field activity. The typical behavioral changes induced by bilateral entorhinal lesions include hyperactivity, reduced habituation of activity, and a gradual time‐dependent return toward control levels. We found that rats treated with total brain gangliosides (30 mg/kg) showed a smaller lesion‐induced increase, consistently lower levels, and greater within‐session habituation of activity than did saline‐treated counterparts. Control rats treated with gangliosides did not exhibit a reduction in activity, suggesting that the effect was on lesion‐induced hyperactivity rather than on activity, per se. Ganglioside‐treated rats showed a slight, but consistently smaller lesion‐induced sprouting response by the septodentate pathway than did untreated counterparts at all postlesion intervals examined (3, 5, 7, and 10 days). The present findings indicate that ganglioside treatments reduce the severity of the initial behavioral effects after entorhinal lesions without enhancing the sprouting by septodentate fibers.
Reduction of cerebral edema with GM1 ganglioside
Authors: Karpiak S. E. , Mahadik S. P.
Published: January 2005

Administration of exogenous gangliosides has been reported to accelerate neurite outgrowth in vitro, and to enhance peripheral nerve regeneration and central nervous system recovery subsequent to damage. After injury, facilitation of CNS recovery with GM1 ganglioside treatment has been postulated to be due to enhanced neuronal regeneration. Since maximal recovery is achieved when experimental animals are treated before injury with GM1 ganglioside, an alternative or parallel mechanism is that gangliosides are “protecting” the CNS by limiting the extent of damage (ie, cell loss, process degeneration, membrane disruption). This may be due to a reduction in the edema subsequent to injury.

In this study, rats were treated for 2 days with 20 mg/kg/day of GM1 ganglioside. On the third day they were subjected to a unilateral lesion (mechanical) of one cerebral hemisphere and given another 20 mg/kg of GM1. On the fourth day brains were removed for analysis of edema resulting from the injury. In treated animals there was a significant reduction in edema as measured either in the entire injured hemisphere (23%) or in the area of injury (33%). No effect was seen outside the damaged area. Since exogenous gangliosides can spontaneously “insert” into membranes, it is postulated that the effect of the GM1 may be due to alterations of membrane processes (eg, lipid hydrolysis, phospholipase activation, levels and membrane action of arachidonic acid, ionic permeation) that are characteristic of edema.
Monoclonal antibody to intermediate filament proteins in astrocytes
Authors: Pixley S. K. R. , Kobayashi Y. , de Vellis J.
Published: January 2005

A monoclonal antibody was developed using rat astrocytes purified in vitro as the starting antigenic material. Selection of the monoclonal was on the basis of astrocyte binding specificity in brain sections using indirect immunofluorescence techniques. The antibody (RBA2) that was chosen was specific for astrocytes in that it did not stain neurons or oligodendrocytes in frozen brain sections. It did, however, show binding to vascular smooth muscle and meningeal cells. The antigenic determinant(s) was determined to be on filaments of the intermediatesize class in cultured astrocytes and fibroblasts. From analysis of binding patterns in various tissues and in immunoblots, it was found that RBA2 cross‐reacted strongly with glial fibrillary acidic protein (GFAP) and desmin. There was a weaker cross‐reactivity to a vimentin‐associated component. It is proposed that this antibody can be used as an astrocyte and blood vessel marker in brain sections, a vimentin marker in cultures and as a probe of intermediate filament composition and distribution.
The threshold quantity of nerve required to induce limb regeneration in the chick embryo
Authors: Sisken B. F. , Fowler I. , Barr E. J. , Kryscio R. J.
Published: January 2005

Wingbuds of 4‐day chick embryos were amputated at the future elbow joint and a segment of embryonic neural tube was implanted longitudinally in the stump. The cross‐sectional area and number of nerve bundles were determined in limbs in which limb regeneration occurred and compared with similar measurments in control limbs without neural tube implant. The number of nerve bundles in regenerated limbs was not significantly greater than in control limbs which did not regenerate. However, the cross‐sectional area of nerve bundles was significantly greater in the limbs that had undergone regeneration. The data support the view that the amount of axoplasm available at the amputation (surface) site is the essential factor in determining the success or failure of regeneration.
Influences of the neural cell adhesion molecule on axon growth and guidance
Authors: Rutishauser U.
Published: January 2005

The neural cell adhesion molecule (NCAM) has been shown to be a ligand in the formation of cell‐cell bonds. This molecule is present on essentially the entire surface of differentiated nerve cells, including the cell body, neurite shaft, and growth cone. In mediating membrane‐membrane adhesion, NCAM appears to ligate with itself, and one of its most obvious functions is in the self‐association of nerve fibers to form fascicles. In most cases fasciculation occurs by the successive elongation of axons along other axons and, therefore, is likely to represent a growth cone‐neurite shaft interaction as well as a shaft‐to‐shaft adhesion. Competition between neurite shafts and the surrounding substrate for growth cone adhesion probably represents a major factor in the branching of nerve bundles. In addition to neurons, NCAM appears on some glial and muscle cells. Recent experiments suggest that this molecule is involved in growth cone guidance along adhesive pathways on glial precursors in the vertebrate central nervous system, and in the initial interaction of axons with muscle prior to synaptogenesis.
Morphological properties and membrane channels of the growth cones induced in PC12 cells by nerve growth factor
Authors: O'Lague P.H. , Huttner S.L. , Vandenberg C.A. , Morrison‐Graham K. , Horn R.
Published: January 2005

Large growth cones were produced in vitro by nerve growth factor (NGF) treatment of multinucleate cells produced by chemical fusion of cells of the neuron‐like clone PC12. These endings were studied both at the light microscopic and ultrastructural levels. The activity of ionic channels at growth cones was recorded with intracellular microelectrodes, patch recording of single channels, and whole cone recording from mechanically isolated growth cones. Morphologically, these large growth cones were characterized by the presence of microspikes and filopodia, by the presence of actin demonstrated immunohistochemically, and by the presence of catecholamine fluorescence. At the ultrastructural level they contained a broad spectrum of organelles with a distribution characteristic of neuronal growth cones, including dense core vesicles, abundant smooth membrane cisternae, microtubules, and a filamentous network. The presence of channels capable of generating action potentials was revealed by intracellular microelectrode recording from the growth cone in the presence of locally applied tetraethylammonium (TEA). TEA appeared to block outward current channels that could effectively shunt inward current activated by depolarization. Action potentials elicited by depolarizing current in the presence of TEA could be blocked reversibly by Cd2+, a specific blocker of Ca channels. These action potentials were often followed by a long after‐hyperpolarization lasting hundreds of milliseconds. This after‐hyperpolarization was similar to that recorded in the cell body of PC12 cells where it appears to be mediated by Ca‐activated K current. Single channel recording from outside‐out excised patches of membrane from the growth cones perfused with KF revealed the presence of voltage sensitive Na channels, Ca‐activated K channels, and K channels resembling delayed rectifier K channels. Macroscopic currents recorded from mechanically isolated growth cones in the “whole cone” configuration showed rapid inward currents at potentials ≥ ‐40 mV, followed by delayed outward currents at more positive potentials, a finding providing additional evidence for the presence of Na and K channels in growth cones.
Myelin basic protein‐responsive blood T lymphocytes in patients with multiple sclerosis
Authors: Hashim G.A. , Brewen M.
Published: January 2005

Previous studies from our laboratory showed the development of circulating T lymphocytes sensitized to myelin basic protein (MBP) in guinea pigs challenged with MBP. Also, lymphocytes sensitized to MBP were found in patients with multiple sclerosis (MS). In this report, we describe the kinetics of MBP‐sensitized lymphocytes in a longitudinal study (140–316 days) of seven MS patients using the MBP‐stimulated active rosette‐forming T cell assay (MBP‐ARFC). Expressed as the ratio of MBP‐ARFC over ARFC (early and 37°C stable rosette‐forming T lymphocytes without added antigen), the results show a considerable degree of variation in the levels of MBP‐ARFC. Although the levels of ARFC during the study period were relatively unchanged for each patient, increases in the MBP‐ARFC/ARFC ratios were associated with the development of neurological symptoms of disease. The results of this study demonstrate the development of T‐cell‐mediated immunity to MBP in patients with MS. Detection of MBP‐sensitive cells was possible during the course of the disease. The level of sensitivity was influenced by the clinical status, degree of neurological deficit, and particular treatment course.
The effect of nerve lesions on the inflammatory response to injury
Authors: Helme R.D. , Andrews P.V.
Published: January 2005

The effects of surgical denervation, capsaicin, and 6‐Hydroxydopamine pretreatment on the inflammatory response to thermal injury have been investigated in the rat. Surgical denervation and capsaicin pretreatment reduced the cellular and exudative reactions to the injury. 6‐Hydroxydopamine appeared to have a selective effect on the exudative reaction only. The effects of surgical denervation are partly explained by local and systemic effects of the procedure.
The effect of inhibiting brain thromboxane biosynthesis on pentylenetetrazole‐induced seizure threshold
Authors: McGinley S. , Centra M. , Lysz T.W.
Published: January 2005

The effect of inhibiting endogenous brain thromboxane (TXB2) on pentylenetetrazole‐induced seizures was studied using the thromboxane synthetase inhibitors OKY‐1581 (20 mg/kg) and UK 38,485 (50 mg/kg). Both compounds selectively decreased (> 90%) TXB2 production in brain measured after 2 min of convulsive activity but had no effect on brain PGE2, PGF2α, or 6‐keto‐PGF1α No effect of these agents on the tonic seizure threshold was observed, whereas 10 mg/kg ip indomethacin, an agent which inhibits both TXB2 and prostaglandin production, reduced the tonic seizure threshold from 78 ± 2.6 mg/kg in controls to 62 ± 3.7 mg/kg. Thus, this study concludes that the availability of TXB2 with convulsant activity is unlikely to be a factor in altering tonic seizure activity observed with indomethacin.
Response of abdominal muscle to graded mechanical loads
Authors: Baker J.P. , Frazier D.T.
Published: January 2005

Abdominal muscle electromyograms were monitored in response to graded mechanical loads added to either inspiration or expiration in anesthetized cats. The surgical preparation, the apparatus, and the levels of loads applied (resistive, tracheal occlusion, and continuous positive pressure) were matched with those employed in our previous study on medullary expiratory neurons [Baker et al, 1979]. Although expiratory neuron firing was significantly increased by each of three graded levels of expiratory resistive loads, abdominal muscles were activated in only about 50% of the animals exposed to the highest‐level resistive load. The smaller resistive loads failed to elicit any discernible abdominal muscle activity. These findings suggest that the lower motor neurons have a higher threshold for activation than the medullary neurons. Recruitment of medullary expiratory neurons and integration of synaptic input at the spinal level must play important roles in the response to expiratory loading. Abdominal muscles did not respond to mechanical loading during inspiration. Bilateral cervical vagotomy eliminated the abdominal muscle responses to expiratory loads.
Prenatal and postnatal hypothyroidism abolishes lesion‐induced noradrenergic sprouting in the adult rat
Authors: Gottesfeld Z. , Butler I. J. , Findley W. E.
Published: January 2005

The effects of altered thyroid states on regeneration in the nervous system are equivocal. This work was undertaken to examine the influence of propylthiouracil‐induced (PTU‐induced) pre‐ and postnatal hypothyroidism on collateral sprouting of noradrenergic (NA) axons in the habenula (Hb), following lesions in the stria medullaris (SM) of the adult rat. Ten pregnant dams were divided into control and PTU‐treated groups. Control rats had free access to food and water and the hypothyroid group received, in addition, 0.05% (w/v) of PTU in their drinking water, beginning on day 12 of gestation and continuing post partum through lactation until the offspring were weaned at age 22 days. The pregnant dams received, in addition, daily injections of thyroxine (25 μg/kg, ip) and only male pups were used in the study. At weaning he pups were removed from the dams and placed in cages with free access to food and water. The hypothyroid offspring received 0.05% (w/v) PTU in the drinking water until sacrificed at 10 weeks of age. At 6 weeks, some rats in each group received bilateral lesions in the SM and the remainder were sham‐operated. All rats were sacrificed 4 weeks after operation. Thus, four groups wre formed: (1) control/sham, (2) control/lesion, (3) PTU/sham, (4) PTU/lesion. Sprouting of NA fibers in discrete regions of the Hb was identified by norepinephrine (NE) levels and by fluorescence histochemistry. Blood levels of thyroid stimulating hormone (TSH) were determined. The results show that pre‐ and postnatal induced chronic hypothyroidism abolished NA sprouing in the partially deafferented Hb. Furthermore, lesions of the SM resulted in a marked decrease in serum TSH levels.
Intraocular kainic acid injection suppresses fast axonal transport in the developing rat optic nerve
Authors: Riccio R. V. , Calle R. P. , Matthews M. A.
Published: January 2005

A single intraocular injection of 1 or 3 nmol kainic acid (KA) into the right eye of rats aged 5 days postnatal (5 dpn) significantly reduced the incorporation of 3H‐proline into retinal proteins and suppressed the amount of 3H‐proline‐labeled materials fast axonally transported in the optic nerve for at least 2 weeks thereafter. Intraocular KA injection within this dose range had no adverse effect on the optic axon population compared to normal nerves determined at 21 dpn; however, doses above 3 nmol (i.e., 6 nmol) caused significant axonal degeneration. Although partially recovered by 21 dpn this effect of KA on protein synthesis and axonal transport suggests that, as in the adult, retinal ganglion cells are also KA‐sensitive during postnatal development.
Modulation of immunoactive levels of DSIP and blood‐brain barrier permeability by lighting and diurnal rhythm
Authors: Banks W. A. , Kastin A. J. , Selznick J. K.
Published: January 2005

The brain and plasma levels of immunoactive delta sleep‐inducing peptide (DSIP) as well as the permeability of the blood‐brain barrier (BBB) to radioiodinated N‐Tyr‐DSIP (125I‐DSIP) were measured at 0400, 0800, 1200, 1600, 2000, and 2400 hr in rats in a normal 12‐hr‐light/12‐hr‐dark cycle and at 0800 in rats in constant light or constant dark. Both brain and blood levels of immunoactivity showed statistically significant dirunal changes, whereas the measurement of BBB permeability varied in a regular fashion over time without the changes reaching statistical significance. Immunoactive levels of DSIP in both plasma and the brain were higher and permeability of the BBB to 125I‐DSIP increased in both the constant light and especially the constant dark groups incomparison with the cycled 0800 group. Diurnal variations continued to occur in the blood levels of immunoactive DSIP in the constant dark animals. Studies with radioiodinated serum albumin (RISA) showed that these findings did not result from a change in brain hemodynamics. Immunoactive levels of DSIP in the plasma correlated with brain immunoactive levels and with BBB permeability to 125I‐DSIP. The increase in penetration of 125I‐DSIP into the brain that occurred with changes in the lighting cycle appeared to be magnified by pre‐treatment with aluminum. The results show interrelationships among various aspects of the neuroendocrine axis for DSIP and their modulation by physiological factors.
Cerebral citric acid cycle enzymes in methionine sulfoximine toxicity
Authors: Ratnakumari L. , Subbalakshmi G. Y. C. V. , Murthy Ch. R. K.
Published: January 2005

The activity levels of pyruvate dehydrogenase, enzymes of the citric acid cycle, aspartate and alanine aminotransferases, and NADP+ ‐isocitrate dehydrogenase were determined in the cerebral cortex, cerebellum, brain stem, corpus striatum, hippocampus, and midbrain regions of normal rats and rats injected with acute and subacute doses of methionine sulfoximine (MSI). In both conditions there was an elevation in the activities of pyruvate dehydrogenase and all the enzymes of the citric acid cycle except malate dehydrogenase, whereas the activities of aminotransferases and NADP+ ‐isocitrate dehydrogenase were suppressed in all the cerebral regions. It is suggested that the operational rates of the citric acid cycle would be enhanced in MSI‐induced hyperammonemia and that there might be a derangement in the transport of reducing equivalents across mitochondrial membranes. It has been suggested that the convulsant action of the drug is due to its effects on ionic gradients and may not be due to depletion of α‐ketoglutarate from the citric acid cycle.