bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interferon Suppresses Sympathetic Neuronal Cell Death Caused by Nerve Growth Factor Deprivation
Authors: Chang Jason Y. , Martin David P. , Johnson Eugene M. 
Published: October 2006

AbstractCultured rat sympathetic neurons die within 48 h after being deprived of nerve growth factor. Addition of interferons (IFN‐α/β or IFN‐γ) prevented the cell death in a dose‐dependent manner. Upon longer periods of nerve growth factor deprivation, IFNs failed to maintain survival. Thus, IFNs retarded neuronal death, but did not prevent it. Ligand binding, autoradiography, and cross‐linking experiments demonstrated the presence of specific IFN‐γ receptors on sympathetic neurons similar to those seen on other cell types. The possible relationships of the death‐suppressing actions of IFNs are compared to the mechanisms of the antiviral or antiproliferative actions of IFNs.
N‐Methyl‐D‐Aspartate Receptor Activation and Ca2+ Account for Poor Pyramidal Cell Structure in Hippocampal Slices
Authors: Feig Sherry , Lipton Peter 
Published: October 2006

AbstractThe CA1 pyramidal cells appear damaged in micrographs of guinea pig hippocampal slices incubated in normal physiological buffer at 36–37°C. This is remedied if slices are incubated in modified buffers for the first 45 min. Cell morphology is improved if this buffer is devoid of added Ca2+ and much improved if it contains N‐methyl‐D‐aspartate (NMDA) receptor antagonists or 0 mM Ca2+ and 10 mM Mg2+. The cells then appear similar to CA1 pyramidal cells in situ. These findings support the notion that NMDA receptor activation and Ca2+, acting in the period immediately after slice preparation, permanently damage CA1 pyramidal cells in vitro.
Characterization of a Nerve Growth Factor‐Stimulated Protein Kinase in PC12 Cells Which Phosphorylates Microtubule‐Associated Protein 2 and pp250
Authors: Landreth Gary E. , Smith Deanna S. , McCabe Craig , Gittinger Cynthia 
Published: October 2006

AbstractTreatment of PC12 cells with nerve growth factor (NGF) resulted in the rapid, but transient, activation of a protein kinase which specifically phosphorylated an endogenous 250‐kDa cytoskeletal protein (pp250). We report that the microtubule‐associated protein, MAP2, is an alternative substrate for the NGF‐activated kinase. NGF treatment maximally activated the kinase within 5 min; however, the activity declined with longer exposure to NGF. The enzyme was localized predominantly in microsomal and soluble fractions and phosphorylated MAP2 on serine and threonine residues. The soluble enzyme was fractionated by DEAE chromatography and gel filtration and had an apparent Mr of 45,000. The enzyme was purified to near homogeneity by chromatofocussing and had a pl of 4.9. Kinetic analysis revealed that NGF treatment caused a sevenfold increase in Vmax for MAP2. The Km with respect to the MAP2 substrate was approximately 50 nM and was not altered by NGF treatment. A novel feature of the NGF‐stimulated enzyme was its sharp dependence on Mn2+ concentration. The active enzyme is likely to be phosphorylated, because inclusion of phosphatase inhibitors was required for recovery of optimal activity and the activity was lost on treatment of the enzyme with alkaline phosphatase. Histones, tubulin, casein, bovine serum albumin, and the ribosomal subunit protein S‐6 were not phosphorylated by this enzyme. The NGF‐stimulated kinase was distinct from A kinase, C kinase, or other NGF‐stimulated kinases. The rapid and transient activation of the protein kinase upon NGF treatment suggests that the enzyme may play a role in signal transduction in PC12 cells.
Autoradiographic Localization of Angiotensin II Receptor Binding Sites on Noradrenergic Neurons of the Locus Coeruleus of the Rat
Authors: Rowe Brian P. , Kalivas Peter W. , Speth Robert C. 
Published: October 2006

AbstractThe locus coeruleus (LC) of the rat was lesioned by microinjection of selective neurotoxins into the brainstem. 6‐Hydroxydopamine (6‐OHDA), 3 μg/μl, given unilaterally at two sites 0.6 mm apart on the rostro‐caudal axis of the LC, was used to lesion catecholamine‐containing neuronal elements. Ibotenic acid, 2.5 μg/0.5 μl, administered similarly was used to lesion nerve cell bodies. Two weeks after administration of the neurotoxin, lesion efficacy was determined based on the norepinephrine content of the cerebral cortex ipsi‐ and contralateral to the lesion. 6‐OHDA lesions of the LC caused a 46% reduction in ipsilateral cortical norepinephrine and a 60% reduction in specific 125I‐[Sar1, Ile8]‐angiotensin II (125I‐SIAII) binding in the LC. Ibotenic acid lesions of the LC caused a 73% reduction in ipsilateral cortical norepinephrine and a 81% reduction in specific 125I‐SIAII binding in the LC. These results indicate that All receptor binding sites in the LC are localized on noradrenergic nerve cell bodies or their dendritic and axonal ramifications within the LC.
Adenosine Transport by Rat and Guinea Pig Synaptosomes: Basis for Differential Sensitivity to Transport Inhibitors
Authors: Shank Richard P. , Baldy William J. 
Published: October 2006

AbstractAdenosine transport by rat and guinea pig synaptosomes was studied to establish the basis for the marked differences in the potency of some transport inhibitors in these species. An analysis of transport kinetics in the presence and absence of nitrobenzylthioinosine (NBTI) using synaptosomes derived from several areas of rat and guinea pig brain indicated that at least three systems contributed to adenosine uptake, the Km values of which were ˜0.4, 3, and 15 μM in both species. In both species, the system with the Km of 3 μM was potently (IC50 of ˜0.3 nM) and selectively inhibited by NBTI. This NBTI‐sensitive system accounted for a greater proportion of the total uptake in the guinea pig than in the rat and was inhibited by dipyridamole, mioflazine, and related compounds more potently in the guinea pig. Preliminary experiments with other species indicate that adenosine transport in the mouse is similar to that in the rat, whereas in the dog and rabbit, it is more like that in the guinea pig. In the rat, none of the systems appeared to require Na+, but the two systems possessing the higher affinities for adenosine were inhibited by veratridine‐ and K+‐induced depolarization. The transport systems were active over a broad pH range, with maximal activity between pH 6.5 and 7.0. Our results are consistent with the possibility that adenosine transport systems may be differentiated into uptake and release systems.
Protein Phosphorylation in Intact Superior Cervical Ganglion During Regeneration
Authors: Watterson J. G. , Good R. , Hearn M. T. W. , Austin L. 
Published: October 2006

AbstractThe incorporation of radioactive phosphate into proteins of both normal and regenerating superior cervical ganglion nerve of the rat is reported. Incorporation studies carried out by in vitro and in vivo methods are compared. In the in vitro method, excised intact ganglia or their homogenates were incubated in the presence of inorganic phosphate or ATP, respectively, under various conditions. Proteins were analyzed by gel electrophoresis followed by autoradiography, in which quantitative but not qualitative differences between regenerating and control cases were apparent. In the in vivo procedure, inorganic phosphate was injected into the living animal 4 h before removal of ganglia. At least fivefold more proteins became labeled in vivo than in vitro, whereas no similarity in the pattern of labeling between the two methods was observed. For example, the most heavily labeled protein in the in vivo method, tentatively identified as micro tubule‐associated protein‐2, was not detected on autoradiograms of proteins labeled by the in vitro method. In this latter method, an 85‐kDa species and growth‐associated pro‐tein‐43 were always labeled, and the extent of their phosphorylation was enhanced by the additional presence of phosphatidylserine and Ca2+, a result indicating that these labeled species are substrates of protein kinase C. The in vitro conditions also led to the labeling of proteins identified as a‐and β‐tubulin. Comparison of the methods suggests that removal of the ganglion interferes with the function of protein phosphorylation systems and that this effect involves elements of the cytoskeleton.
Presence of the Plasma Membrane Proteolipid (Plasmolipin) in Myelin
Authors: Cochary Elizabeth F. , Bizzozero Oscar A. , Sapirstein Victor S. , Nolan Charles E. , Fischer Itzhak 
Published: October 2006

AbstractPlasma membrane proteolipid (plasmolipin), which was originally isolated from kidney membranes, has also been shown to be present in brain. In this study, we examined the distribution of plasmolipin in brain regions, myelin, and oligodendroglial membranes. Immunoblot analysis of different brain regions revealed that plasmolipin levels were higher in regions rich in white matter. Plasmolipin was also detected in myelin, myelin subfractions, and oligodendroglial membranes. Immunocytochemical analysis of the cerebellum revealed that plasmolipin was localized in the myelinated tracts. Plasmolipin levels in myelin were enriched during five successive cycles of myelin purification, similar to the enrichment of myelin proteolipid apoprotein (PLP) and myelin basic protein (MBP). In contrast, levels of Na+, K+‐ATPase and a 70‐kDa protein were decreased. When myelin or white matter was extracted with chloroform/methanol, it contained, in addition to PLP, a significant amount of plasmolipin. Quantitative immunoblot analysis suggested that plasmolipin constitutes in the range of 2.2–4.8% of total myelin protein. Plasmolipin, purified from kidney membranes, was detected by silver stain on gels at 18 kDa and did not show immunological cross‐reactivity with either PLP or MBP. Thus, it is concluded that plasmolipin is present in myelin, possibly as a component of the oligodendroglial plasma membrane, but is structurally and immunologically different from the previously characterized myelin proteolipids.
An Inhibitor of Endopeptidase‐24.15 Blocks the Degradation of Intraventricularly Administered Dynorphins
Authors: Molineaux Christopher J. , Ayala Julia M. 
Published: October 2006

AbstractConversion of the octapeptide dynorphin (Dyn) A‐(1–8) to Leu5‐enkephalin (LE) by endopeptidase EC 3.4.24.15 (EP‐24,15) in vivo was examined using the technique of ventriculocisternal perfusion. Peptides were administered intra‐cerebroventricularly in the presence or absence of the EP‐24.15 inhibitor N‐[1‐(R,S)‐carboxy‐3‐phenylpropyl]‐Ala‐Ala‐Phe‐p‐aminobenzoate (cFPAAF‐pAB) via cannulae placed into the lateral ventricle of urethane‐anesthetized rats. The concentration of Dyn‐like peptides and LE within the CSF was monitored by radioimmunoassay in samples of CSF taken from a second cannula placed in the cisterna magna. In the absence of inhibitor, <5% of the Dyn A‐(1–8) administered was recovered in CSF. Immunoreactive LE, which is normally not found in CSF, increased rapidly in content following Dyn A‐(1–8) infusion, an observation suggesting that the larger peptide is converted to LE. When the inhibitor cFPAAF‐pAB was coadministered with Dyn A‐(1–8), the concentration of immunoreactive Dyn A‐(1–8) after 5 min was 40 times higher than that found in the absence of inhibitor. The angiotensin converting enzyme inhibitor captopril reduced the degradation of Dyn A‐(1–8) to a much lesser degree. The inhibitor of EP‐24.15 also afforded some protection of other Dyn‐like peptides. No EP‐24.15 activity was found in rat CSF, whereas high activity was found in the choroid plexus. Taken together, these data clearly indicate that an ectoenzyme form of EP‐24.15 rapidly converts intra‐cerebroventricularly administered Dyn‐like peptides to LE. Key Words: Dynorphin—Enkephalin—Enkephalinase—Ectoenzyme—Ventriculocisternal—Angiotensin converting enzyme. Molíneaux C. J. and Ayala J. M. An inhibitor of endopeptidase‐24.15 blocks the degradation of intraventricularly administered dynorphins. J. Neurochem. 55, 611–618 (1990).
Imaging the Dopamine Uptake Site with Ex Vivo [18F]GBR 13119 Binding Autoradiography in Rat Brain
Authors: Ciliax Brian J. , Kilbourn Michael R. , Haka Michael S. , Penney John B. 
Published: October 2006

AbstractWe studied the binding of [18F]GBR 13119 {1‐[[(4‐[18F]fluorophenyl) (phenyl)methoxy]ethyl]‐4‐(3‐phenylpropyl)piperazine} to rat brain with autoradiography after intravenous injection. The rank order of binding was dorsal striatum > nucleus accumbens = olfactory tubercle > sub‐stantia nigra = ventral tegmental area > other areas. Binding was blocked by prior injection of dopamine uptake blockers but not by injection of dopamine receptor antagonists or drugs that bind to the dialkylpiperazine site. Unilateral 6‐hydroxy dopamine lesions of dopamine neurons caused a marked decrease in striatal and nigral binding on the side of the lesion. We conclude that intravenous injection of [18F]GBR 13119 provides a useful marker of presynaptic dopamine uptake sites.
Distinct Muscarinic Receptor Subtypes Differentially Modulate Acetylcholine Release from Corticocerebral Synaptosomes
Authors: Pittel Zipora , Heldman Eliahu , Rubinstein Rachel , Cohen Sasson 
Published: October 2006

AbstractThe effect of McN‐A‐343 and oxotremorine on acetylcholine (ACh) release and choline (Ch) transport was studied in corticocerebral synaptosomes of the guinea pig. The synaptosomes were preloaded with [3H]Ch after treatment with the irreversible cholinesterase inhibitor, diisopropyl fluorophosphate, and then tested for their ability to release isotope‐labeled ACh and Ch in the presence and absence of these agents. The kinetics of release were determined at the resting state (basal release) and in the presence of 50 mM K+. Under either condition, McN‐A‐343 enhanced the release of isotope‐labeled ACh, whereas oxotremorine inhibited the K+‐evoked release but had no effect on the basal release. The enhancing effect of McN‐A‐343 on basal ACh release was fully blocked by the selective M1 muscarinic antagonist, pirenzepine (100 nM). In contrast to its enhancing effect on ACh release, McN‐A‐343 potently inhibited Ch efflux as well as Ch influx. These effects were not blocked by atropine, a nonselective muscarinic antagonist. Oxotremorine had no effect on Ch transport. Binding studies showed that McN‐A‐343 was 3.6‐fold more potent in displacing radiolabeled quinuclidinyl benzilate from cerebral cortex muscarinic receptors (mostly M1 subtype) than from cerebellar receptors (mostly M2 subtype), whereas oxotremorine was 2.6‐fold more potent in the cerebellum. The displacements of radio‐labeled pirenzepine and m‐dioxolane confirmed the M1 subtype preference of McN‐A‐343 and the M2 subtype preference of oxotremorine. These observations suggest that (a) activation of one subpopulation of muscarinic receptors by McN‐A‐343 enhances ACh release, whereas activation of another subpopulation by oxotremorine decreases this process (these subpopulations may correspond to the M1 and M2 subtypes, respectively), (b) the effect of the stimulatory receptors is pronounced at the resting state and that of the inhibitory receptors during depolarization, and (c) activation of the stimulatory receptors may be inversely related to the activity of the Ch transporter.
Posttetanic Long‐Term Potentiation in Rat Dentate Area Increases Postsynaptic 411B Immunoreactivity
Authors: Bullock Sarah , Lössner Bernd , Krug Manfred , Frey Sabine , Rose Steven P. R. , Matthies Hansjürgen 
Published: October 2006

Abstract411B is a monoclonal antibody raised to chick forebrain postsynaptic densities (PSDs) which also recognises an antigen in brain tissue from adult Wistar rats but not liver, heart, or lung. This antigen is enriched in the PSD fraction and appears to be a useful biochemical marker for plastic changes of postsynaptic structures in the rat brain. The aim of this study was to investigate whether 411B immunoreactivity is changed in various hippocampal subregions by post‐tetanic long‐term potentiation (LTP). LTP was elicited in freely moving rats by applying four trains of 300 square‐wave pulses (frequency 200 Hz, pulse duration 0.2 ms, and intensity 300 mA) into the right perforant path; this included an increase in transmission efficacy at the ipsilateral perforant path‐granular cell synapse of the dentate gyrus lasting several days. Eight hours after tetanisation, antigens recognised by monoclonal 411B and a polyclonal anti‐actin antiserum were assayed in lysed homogenates of ipsi‐ and contralateral CA1, CA3, and CA4/dentate area hippocampal subfields as well as in visual cortex, cerebellum, and olfactory bulb dissected from LTP rats, and compared to passive controls. Under these experimental conditions, tetanisation of the perforant path resulted in a significant increase in the titre of 411B in the ipsilateral CA4/dentate area subfield (+34.0%; p < 0.001) compared with passive controls, whereas in all other brain regions studied no differences between experimental and control rats were observed. In no region were anti‐actin titres significantly different from controls. Our results support the hypothesis that the “late phase” of posttetanic LTP is accompanied by, or even based on, macromolecular changes elicited at the postsynaptic site of perforant path‐granular cell synapses.
Induction of Nerve Growth Factor Gene Expression by 12‐O‐Tetradecanoyl Phorbol 13‐Acetate
Authors: D'Mello Santosh R. , Heinrich Gerhard 
Published: October 2006

AbstractNerve injury leads to activation of fibroblasts, including stimulation of nerve growth factor (NGF) gene expression. Although interleukin‐1 has been implicated as a mediator of NGF gene induction, the underlying mechanisms are not known. We investigated whether 12‐O‐tetradecanoyl phorbol 13‐acetate (TPA), also a known stimulator of protein kinase C, regulates NGF gene expression. We show here that TPA stimulates NGF mRNA in mouse kidney and L929 fibroblasts but not in dispersed salivary cells. NGF mRNA stimulation in L929 cells is delayed by 2h, is transient, and is followed by a parallel increase in NGF secretion. The induction of NGF mRNA is inhibited by cycloheximide. NGF mRNA levels decrease to similar values after 4 h of incubation with actinomycin D alone or in combination with TPA. These results indicate that the TPA response is cell specific and suggest that it is mediated at the transcriptional level via newly synthesized protein.
Neuronal Intermediate Filament Expression During Neurite Outgrowth from Explanted Goldfish Retina: Effect of Retinoic Acid
Authors: Hall Christina M. , Else Cindy , Schechter Nisson 
Published: October 2006

Abstract: Regulation of the goldfish neuronal intermediate filament proteins ON1 and ON2 was investigated in a retinal explant system. The synthesis of these proteins in explanted retina decreased with increasing time in culture, despite continuing neurite outgrowth. Thus, ON1/ON2 neurofilament expression is regulated independently from neurite outgrowth. During regeneration of the goldfish optic nerve in vivo, the expression of these proteins increased during the later phase of the process, when growing axons make contact with the optic tectum. The declining synthesis of ON1 and ON2 during neurite outgrowth in culture suggests that factors extrinsic to the retina are necessary to support synthesis of these proteins.Treating retinal explants with retinoic acid stimulated the synthesis of the ON1/ON2 proteins in a dose‐dependent manner. This stimulation was effective during a period of declining synthesis of the ON1/ON2 proteins, restoring their synthesis towards initial levels of expression. These results show that retinoic acid serves as a modulator of neurofilament expression in this in vitro model of nerve regeneration.
Incorporation of Very‐Long‐Chain Fatty Acids into Sphingolipids of Cultured Neural Cells
Authors: Saito Mariko , Saito Mitsuo 
Published: October 2006

AbstractWe examined effects of exogenous very‐long‐chain fatty acids on lipids of cultured chick neurons and astrocytes. When chick neurons were incubated in chemically defined medium containing 10 μMnervonic acid (C24:1) for 7 days, it was found that a major fatty acid moiety of gangliosides and sphingomyelin was nervonic acid itself, which was not normally detected in the sphingolipid fraction. This alteration in the fatty acid composition apparently occurred in each ganglioside species. Under these experimental conditions, nervonic acid was not found in the glycerophospholipid fraction, and the amounts of triacylglycerol and free nervonic acid increased. Addition of behenic acid (C22:0) or erucic acid (C22:l) also induced changes in the fatty acid composition of gangliosides. When chick astrocytes were incubated in the presence of 10 μM nervonic acid for 7 days, no significant change was observed in the fatty acid composition of gangliosides. These studies indicate that the manipulation of the fatty acid moiety of sphingolipids in cultured neurons is possible.
Epidermal Growth Factor Enhances Striatal Dopaminergic Parameters in the 1‐Methyl‐4‐Phenyl‐l, 2, 3, 6‐Tetrahydropyridine‐Treated Mouse
Authors: Hadjiconstantinou Maria , Fitkin James G. , Dalia Asad , Neff Norton H. 
Published: October 2006

AbstractIntracerebroventricular infusion of epidermal growth factor (EOF) into mice with 1‐methyl‐4‐phenyl‐1, 2, 3, 6‐tetrahydropyridine (MPTP)‐induced degeneration of dopaminergic nigrostriatal neurons partially enhanced the content of dopamine (DA) and 3, 4‐dihydroxyphenylacetic acid as well as the activity of tyrosine hydroxylase in the striatum. EGF also enhanced these parameters in control, unlesioned animals. Neurotrophic activity also was observed in embryonic mesencephalic cultures, where EGF enhanced DA uptake after a lesion with the neurotoxic metabolite of MPTP, 1‐methyl‐4‐phenylpyridinium ion. Our in vivo and in vitro studies suggest that EGF may be a neurotrophic factor for dopaminergic neurons, or may act indirectly by inducing the release of a dopaminergic trophic factor from other cells.
Molecular Cloning and Expression of Biologically Active Human Glia Maturation Factor‐β
Authors: Kaplan Ruth , Zaheer Asgar , Jaye Michael , Lim Ramon 
Published: October 2006

AbstractGlia maturation factor‐β, a protein found in the brains of all vertebrates thus far examined, appears to play a role in the differentiation, maintenance, and regeneration of the nervous system. Using oligonucleotide probes based on the sequences of three tryptic peptides derived from bovine glia maturation factor‐β, we screened a human brainstem cDNA library in δll. A 0.7‐kb clone was isolated, sequenced in its entirety, and found to encode a polypeptide of 142 amino acids which contained regions identical to the three bovine peptides. This polypeptide, human recombinant glia maturation factor‐β, has been expressed in Escherichia coli and found to possess structural characteristics and biological activity indistinguishable from those of the native bovine protein.