bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endogenous ADP‐Ribosylation in Brain: Initial Characterization of Substrate Proteins
Authors: Duman Ronald S. , Terwilliger Rose Z. , Nestler Eric J. 
Published: October 2006

AbstractCholera and pertussis toxin‐mediated ADP‐ribo‐sylation has been used extensively to study regulation of guanine nucleotide binding proteins (G proteins) in the nervous system, but much less is known about possible endogenous ADP‐ribosylation of G proteins in brain. The present study demonstrates endogenous ADP‐ribosylation, in the absence of cholera and pertussis toxins, of four predominate proteins in homogenates of rat cerebral cortex. These proteins showed apparent molecular masses of 20, 42, 45, and SO kDa by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. The 42‐ and 45‐kDa proteins comigrated precisely with the major cholera toxin‐labeled bands. Furthermore, the endogenous ADP‐ribosylated and cholera toxin‐ADP‐ribosylated bands yielded identical 32p‐labeled peptide fragments by one‐dimensional peptide mapping, indicating that they are probably the same proteins, presumably the α‐subunits of Gs. In contrast, peptide maps of the 50‐kDa protein, which migrated close to a 48‐kDa cholera toxin‐labeled band, demonstrated that this protein is distinct from the toxin‐labeled band and from Gsα. Levels of endogenous ADP‐ribosylation activity showed regional heterogeneity in brain, with a nearly threefold variation observed among the brain regions examined. Chronic administration (7 days) of corticosterone significantly increased overall levels of endogenous ADP‐ribosylation, indicating that components of this system may be under hormonal control in vivo. Attempts to identify neurotransmitters or second messenger systems that regulate endogenous ADP‐ribosylation activity in brain have so far been unsuccessful with one exception. Sodium nitroprusside, which increases the formation of nitric oxide, dramatically stimulated the endogenous ADP‐ribosylation of a 36‐kDa protein, as reported previously by others, and, under certain conditions, also stimulated ADP‐ribosylation of the 42‐, 45‐, and 50‐kDa proteins, although to a lesser extent than the 36‐kDa protein. These findings demonstrate that GSα and additional, as yet unidentified, proteins are ADP‐ribosylated in brain in the absence of bacterial toxins and suggest that such endogenous covalent modification may regulate the functional activity of these proteins in vivo.
Intranigral Iron Injection Induces Behavioral and Biochemical “Parkinsonism” in Rats
Authors: Ben‐Shachar D. , Youdim M. B. H. 
Published: October 2006

AbstractElevated iron concentrations in the substantia nigra (SN) pars compacta have been implicated in the development of idiopathic Parkinson's disease. Because, as a transitional metal, iron promotes free radical formation, the role of iron in the degeneration of the nigrostriatal dopamine neurons in Parkinson's disease has received much attention. This study further investigates the cytotoxic effects of iron in the SN. Various concentrations of FeCl3 (1, 5, and 50 μg of Fe3+ in 5 μl) were unilaterally injected into the SN of adult rats. The two lower doses of iron had no effect on striatal dopamine levels or on the behavioral responses of the rats. However, injection of 50 μg of Fe3+ resulted in a substantial selective decrease of striaial dopamine (95%), 3,4‐dihydroxyphenylacetic acid (82%), and homo‐vanillic acid (45%), without any change in norepinephrine concentration. Dopamine‐related behavioral responses, such as spontaneous movements in a novel space and rearing, were significantly impaired, whereas amphetamine administration induced ipsilatcral rotation in the iron‐treated rats. The present study indicates that the nigrostriatal dopamine neurons are susceptible to the presence of ionic iron and thus supports the assumption that iron initiates dopaminergic neu‐rodegeneration in Parkinson's disease.
A One‐Step Procedure for Isolation of Poly(A)+ mRNA from Isolated Brain Capillaries and Endothelial Cells in Culture
Authors: Boado Ruben J. , Pardridge William M. 
Published: October 2006

AbstractThe study of the regulation of low‐abundance blood‐brain barrier (BBB) transcripts either in isolated brain microvessels or in endothelial cells in tissue culture (ECL cells) requires isolation of poly(A)+ mRNA. Therefore, we describe here a single‐step method for isolation of polyfA)+ mRNA from brain capillaries or ECL cells using proteinase K/sodium dodecyl sulfate cell lysis and oligo‐de‐oxythymidine cellulose affinity chromatography. The yield of poly(A)+ mRNA was—15‐19 #g/g of brain or choroid plexus, 14‐17 μg per batch of isolated capillaries in a single bovine forebrain (190 g), and 6‐12 μg/107 ECL cells. Northern blot analysis showed characteristic and undegraded 2.1‐and 1.7‐kb actin transcripts in brain capillaries and a 2.1‐kb actin mRNA in brain and ECL cells. Northern analysis was also used to quantify the glucose transporter type I transcript, which is very rare in basal ECL cells, and this mRNA was shown to be up‐regulated by glucose deprivation. This method represents a significant improvement in the mRNA yield for brain capillaries or cultured endothelial cells compared with the conventional two‐step method.
Heterogeneity of N‐Methyl‐D‐Aspartate Receptors Regulating the Release of Dopamine and Acetylcholine from Striatal Slices
Authors: Cai Ning‐sheng , Kiss Béla , Erdö Sándor L. 
Published: October 2006

AbstractIn an attempt to examine some functional characteristics of the N‐methyl‐D‐aspartate (NMDA) receptor complex, the NMDA‐evoked effluxes of endogenous dopamine (DA) and [3H]acetylcholine ([3H]ACh) were simultaneously examined in a rat Striatal slice preparation. NMDA induced release of both DA and ACh in a concentration‐dependent, Ca2+‐, Mg2+‐, and tetrodotoxin‐sensitive manner. These release responses were remarkably reduced by long‐term pre‐treatment with a low concentration of NMDA. an indication of the desensitization of the NMDA receptor. Glycine was potent in reversing the desensitization‐related reduction of DA release but failed to reverse the diminution of ACh release in the same slices. Our results indicate that the NMDA receptors regulating the release of DA and ACh are different with respect to their glycine modulatory site. This finding is consistent with a functional heterogeneity of the NMDA receptor complex in the rat striatum.
Presynaptic Glutamate Receptors Modulate Dopamine Release from Striatal Synaptosomes
Authors: Wang James K. T. 
Published: October 2006

AbstractThe wide‐ranging neuronal actions of glutamate arc thought to be mediated by postsynaptic N‐methyl‐D‐aspartate (NMDA) and non‐NMDA receptors. The present report demonstrates the existence of presynaptic glutamate receptors in isolated striatal dopaminergic nerve terminals (synaptosomes). Activation of these receptors, by NMDA in the absence of Mg2+ and presence of glycine and by non‐NMDA agonists in the presence of Mg2+, results in Ca2+‐depeodent release of dopamine from striatal synaptosomes. The release stimulated by NMDA is blocked by Mg2+ and by selective NMDA antagonists, whereas the release stimulated by selective non‐NMDA agonists is blocked by a non‐NMDA antagonist but not by Mg2+ or NMDA antagonists. Thus, these presynaptic glutamate receptors, localized on dopaminergic terminals in the striatum, appear to be pharmacologically similar to both the NMDA and the non‐NMDA postsynaptic receptors. By modulating the release of dopamine, these presynaptic receptors may play an important rote in transmitter interactions in die striatum.
Tumor Necrosis Factor‐Induced Proliferation of Astrocytes from Mature Brain Is Associated with Down‐Regulation of Glial Fibrillary Acidic Protein mRNA
Authors: Selmaj Krzysztof , Shafit‐Zagardo Bridget , Aquino Dennis A. , Farooq Muhammad , Raine Cedric S. , Norton William T. , Brosnan Celia F. 
Published: October 2006

AbstractPrevious results from this laboratory have shown that tumor necrosis factor (TNF) is mitogenic for bovine astrocytes in chemically defined (CO) medium. The maximum mitogenic response was detected with 200 U/ml at 48 h. We have now extended these studies to assess the effect of TNF on message levels for the intermediate filament proteins glial fibrillary acidic protein (GFAP) and vimentin. The results have shown that, whereas TNF had only a slight effect on vimentin mRNA, TNF induced a marked decrease to 4.3 ± 2.0% of controls in GFAP mRNA which was both time and dose dependent. The lowest effective dose was 50 U/ml and the maximal effective dose was 200 U/ml. Kinetic analysis of this response demonstrated that a marked decrease in GFAP mRNA was present at 12 h and continued to decrease through 72 h. To determine the reversibility of the TNF effect, astrocyte cultures were exposed to 200 U/ml TNF for varying periods of tee and then cultured in fresh CD medium. A 1‐h pulse with TNF was sufficient to reduce GFAP mRNA levels when measured 24 h later. However, cultures incubated with 200 U/ml TNF for 48 h followed by incubation in CD medium without TNF for 7 days showed that GFAP mRNA levels had returned to 60% of the control values. Nuclear runoff assays showed that the effect of TNF on GFAP mRNA was at the posttranscriptional level. Polyacrylamide gel electrophoretic analysis of astrocyte cytoskeletal proteins demonstrated that GFAP levels were reduced after a 5‐day incubation with 200 U/ml TNF whereas protein levels of vimentin and actin were not significantly changed. Western blots confirmed that GFAP levels were reduced to 36% of the control values. Thus the effect of TNF on GFAP mRNA expression was not due to a generalized effect on intermediate filament metabolism.
Developmental Expression of HNK‐1‐Reactive Antigens in Rat Cerebral Cortex and Molecular Heterogeneity of Sulfoglucuronylneolactotetraosylceramide in CNS Versus PNS
Authors: Chou Denise K. H. , Prasadarao Nemani , Koul Omanand , Jungalwala Firoze B. 
Published: October 2006

AbstractMonoclonal antibody HNK‐1 reacts with a carbohydrate epitope present in proteins, proteoglycans, and sulfoglucuronylglycolipids (SGGLs). On high‐performance TLC plates, SGGLs of the CNS from several species migrated consistently slower than those from the PNS, a result indicating possible differences in the structures. The structural characteristics of the major SGGL, sulfoglucuronylneolac‐totetraosylceramide (SGGL‐1), from CNS was compared with those of SGGL‐1 from PNS. Although the composition, sequence, and linkages of the carbohydrate moiety of the SGGL‐1 species were identical, SGGL‐1 from CNS contained mainly short‐chain fatty acids, 16:0, 18:0, and 18:1, amounting to 85% of the total fatty acids, whereas SGGL‐1 from PNS contained large proportions (59%) of long‐chain fatty acids (> 18:0). These differences in the fatty acid composition accounted for the different migration pattern observed. The developmental expression of SGGLs and HNK‐1‐reactive proteins was studied in rat cerebral cortex between embryonic day (ED) 15 to adulthood. SGGLs in the rat cortex were maximally expressed around ED 19 and almost completely disappeared by postnatal day (PD) 20. This expression was contrary to their increasing expression in the cerebellum and sciatic nerve with postnatal development. Six to eight protein bands with a molecular mass of > 160 kDa were HNK‐1 reactive in the rat cerebral cortex at different ages. The major HNK‐1 reactivity to the 160‐kDa protein band seen in ED 19 to PD 10 cortex decreased and completely disappeared from the adult cortex, whereas several other proteins remained HNK‐1 reactive even in the adult. Western blot analyses of the neural cell adhesion molecules (N‐CAMs) during development of the rat cortex with a polyclonal anti‐N‐CAM antibody showed that the major HNK‐1‐reactive protein bands were not N‐CAMs. Between PD 1 and 10, 190–200‐kDa N‐CAM was the major N‐CAM, and between PD 15 to adulthood, 180‐kDa N‐CAM was the only N‐CAM present in the rat cortex.
Activation of Excitatory Amino Acid Receptors Cannot Alone Account for Anoxia‐Induced Impairment of Protein Synthesis in Rat Hippocampal Slices
Authors: Carter Adrian J. , Müller R. Enzio 
Published: October 2006

AbstractWe have investigated the contribution of excitatory amino acid receptor activation to the inhibition of protein synthesis observed after anoxia in rat hippocampal slices. Protein synthesis was assessed in normoxic medium by measuring the incorporation of [14C]lysine into perchloric acid‐insoluble tissue extracts. Protein synthesis was impaired after anoxia; the extent of inhibition was dependent on the duration of anoxia and on the time allowed for postanoxic recovery. There was a similar impairment under normoxic conditions when the N‐methyl‐D‐aspartate (NMDA) receptor channel was activated by removing Mg2+ and adding NMDA. This was prevented by noncompetitive antagonists of the NMDA receptor channel (MK‐801, phencyclidine, and N‐allylnor‐metazocine). In contrast, incubation with the NMDA antagonists failed to prevent the protein synthesis inhibition caused by anoxia, although it moderately facilitated the postanoxic recovery. Protein synthesis was also impaired under normoxic conditions after incubation with quisqualate and kainate, agonists of non‐NMDA glutamate receptors. This impairment was prevented by 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione, an antagonist of these receptors. Although 6‐cyano‐7‐nitroquin‐oxaline‐2,3‐dione alone failed to prevent anoxic damage, when used in combination with an NMDA antagonist it did partially enhance the later recovery of protein synthesis. These results indicate that the activation of excitatory amino acid receptors cannot alone account for anoxia‐induced impairment of protein synthesis in rat hippocampal slices.
Different Mechanisms of β‐Adrenoceptor Down‐Regulation by Chronic Imipramine and Electroconvulsive Treatment: Possible Role for Protein Kinase C
Authors: Nalepa Irena , Vetulani Jerzy 
Published: October 2006

AbstractThe aim of this study was to find out how protein kinase C (PKC) is involved in down‐regulation of the β‐adrenoceptor in cortical slices of rats subjected to antidepressant treatments. The responses of the cyclic AMP generating system to forskolin, isoproterenol, and noradrenaline were tested in the absence and presence of a PKC activator, 12‐O‐tetradecanoylphorbol 13‐acetate (TPA). The anti‐depressive treatments applied were chronic administration of imipramine and electroconvulsive shock. The potentiating effect of the phorbol ester on cyclic AMP response to isoproterenol was retained in imipramine‐treated animals and even accentuated in rats subjected to electroconvulsive treatment; the TPA effect on noradrenaline‐induced cyclic AMP response was blunted in rats receiving imipramine. but augmented in those receiving electroconvulsive treatment. In imipramine‐treated rats the β‐down‐regulation was still evident in the presence of TPA; after electroconvulsive treatment the phorbol ester‐induced potentiation was so high that no significant β‐downregulation could be observed. No procedure affected the response to forskolin. The β‐down‐regulation that develops during chronic imipramine treatment differs from that caused by chronic electroconvulsive treatment; in both cases it is not related to the direct effect on adenylate cyclase.
Kininogen and Kinin in Experimental Spinal Cord Injury
Authors: Xu Jian , Hsu Chung Y. , Junker Herman , Chao Steven , Hogan Edward L. , Chao Julie 
Published: October 2006

AbstractActivation of the kallikrein‐kinin system has been implicated in the pathogenesis of vasogenic brain edema and posttraumatic vascular injury. We determined the levels of kininogen and kinin in an experimental spinal cord injury model in the rat. Kininogen content in traumatized cord segments increased in a time‐dependent manner. Western blot analysis showed that the kininogen in traumatized cord comigrates with 68K low‐molecular‐weight kininogen or T‐ kininogen. Trypsin treatment of the kininogen in traumatized cord released both bradykinin and T‐kinin, which were separated by HPLC and quantified with a kinin radioimmu‐ noassay. Endogenous kinin levels in the frozen spinal cord also increased up to 40‐fold 2 h after injury as compared with controls. The results demonstrate an increased accumulation of kininogen and its conversion to vasoactive kinins in experimental spinal cord injury.
Prolonged Alterations in Canine Striatal Dopamine Metabolism Following Subtoxic Doses of l‐Methyl‐4‐Phenyl‐ 1,2,3,6‐Tetrahydropyridine (MPTP) and 4′‐Amino‐MPTP Are Linked to the Persistence of Pyridinium Metabolites
Authors: Johannessen An N. , Sobotka Thomas J. , Weise Virginia K. , Markey Sanford P. 
Published: October 2006

AbstractSingle toxic doses of l‐methyl‐4‐phenyl‐l,2,3,6‐ tetrahydropyridine (MPTP)‐HCI (2.5 mg/kg i.v.) and 4′‐ amino‐MPTP · 2HCI (22.5 mg/kg) induce loss of striatal dopamine (DA) and tyrosine hydroxylase (TH) activity and of nigral DA neurons in the dog. To examine the subacute neurochemical changes induced by low doses of MPTP and 4′‐ amino‐MPTP, dose‐response studies of these compounds were carried out in the dog, using 6‐ and 3‐week survival times for these two compounds, respectively. Low single doses of MPTP (1.0, 0.5, and 0.1 mg/kg i.v.) and 4′‐amino‐MPTP (15, 7.5, and 3.75 mg/kg i.v.) did not cause depletion of canine striatal DA or TH or a loss of nigral neurons. However, levels of the DA metabolites 3,4‐dihydroxyphenylacetic acid (DO‐ PAC) and homovanillic acid (HVA) were decreased in a doserelated fashion, with significant loss of DOPAC being evident 6 weeks after the lowest administered dose of MPTP and 3 weeks after 4′‐amino‐MPTP. This selective loss of DA metabolites following nontoxic doses of MPTP and 4′‐amino‐ MPTP led to a shift in the ratio of DA to DOPAC or HVA, which was characteristic for each compound. The measurement of striatal l‐methyl‐4‐phenylpyridinium (MPP+) and 4′‐amino‐MPP+ levels revealed that high concentrations (up to 150 μM) persist in the striatum for weeks following administration of a single nontoxic dose of MPTP or 4′‐amino‐ MPTP. A causal relationship between the striatal concentration of MPP+ or 4‐amino‐MPP+ and the change in DA metabolism as reflected in the DA/DOPAC ratio is suggested by a significant correlation between these measures. It is suggested that presynaptic sequestration and retention of MPP+ and 4′‐amino‐MPP+ by striatal DA terminals result in the inhibition of the monoamine oxidase contained within these terminals.
Nucleotide Sequence and Regulatory Studies of VGF, a Nervous System‐Specific mRNA That Is Rapidly and Relatively Selectively Induced by Nerve Growth Factor
Authors: Salton Stephen R. J. 
Published: October 2006

AbstractA nervous system‐specific mRNA that is rapidly induced in PC 12 cells to a greater extent by nerve growth factor (NGF) than by epidermal growth factor treatment has been cloned. The polypeptide deduced from the nucleic acid sequence of the NGF33.1 cDNA clone contains regions of amino acid sequence identity with that predicted by the cDNA clone VGF, and further analysis suggests that both NGF33.1 and VGF cDNA clones very likely correspond to the same mRNA (VGF). In this report both the nucleic acid sequence that corresponds to VGF mRNA and the polypeptide predicted by the NGF33.1 cDNA clone are presented. Genomic Southern analysis and database comparison did not detect additional sequences with high homology to the VGF gene. Induction of VGF mRNA by depolarization and phorbol 12‐myristate 13‐acetate treatment was greater than by serum stimulation or protein kinase A pathway activation. These studies suggest that VGF mRNA is induced to the greatest extent by NGF treatment and that VGF is one of the most rapidly regulated neuronal mRNAs identified in PC12 cells.
Recombinant Human and Rat Ciliary Neurotrophic Factors
Authors: Masiakowski Piotr , Liu Haoxing , Radziejewski Czeslaw , Lottspeich Friedrich , Oberthuer Walter , Wong Vivien , Lindsay Ronald M. , Furth Mark E. , Panayotatos Nikos 
Published: October 2006

AbstractThe human ciliary neurotrophic factor (CNTF) gene was identified and cloned, based on homology with the recently cloned rat cDNA. The gene encodes a protein of 200 amino acids, which shares about 80% sequence identity with rat and rabbit CNTF and, like these homologues, lacks an apparent secretion signal sequence. The human CNTF gene, like the rat gene, appears to contain a single intron separating two protein coding exons. An intronless human CNTF gene was constructed by the use of polymerase chain reactions and introduced into vectors designed for expression of foreign proteins in E. coli. The rat CNTF gene was also introduced into similar vectors. Both the human and rat proteins were expressed at exceptionally high levels, at 20–40% and 60–70% of total protein, respectively. Extraction of the recombinant proteins from inclusion bodies by guanidinium chloride, followed by two column chromatography steps, produced high yields of pure CNTF that supported survival and neurite outgrowth from embryonic chick ciliary neurons in culture. The biological activity of both recombinant proteins was comparable to that of native rat CNTF.
Biological and Immunological Properties of Recombinant Human, Rat, and Chicken Nerve Growth Factors: A Comparative Study
Authors: Ibáñez Carlos F. , Hallböök Finn , Söderström Stine , Ebendal Ted , Perssdon Håkan 
Published: October 2006

AbstractBiological and immunological properties of recombinant human, rat, and chicken nerve growth factors (NGFs) were studied and compared. Recombinant NGF proteins were produced in a transient expression system using COS cells and levels of secreted NGF protein were assessed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of conditioned media from in vivo [35S]cysteine‐labeled cell cultures. Antigenic differences among the three NGFs were studied by immunoblotting and immunoprecipitation of secreted cell products using a rabbit polyclonal antiserum against purified mouse NGF, and by a two‐site enzyme im‐munoassay (EIA) with a monoclonal antibody against mouse NGF. Although all three NGFs were recognized equally well in the immunoblotting, only one‐third of the chicken NGF protein could be detected by immunoprecipitation or by the EIA as compared to the rat and human NGFs. Thus, changes in the three‐dimensional structure of the NGF molecule are most likely responsible for the antigenic differences between avian and mammalian NGFs. The three NGF proteins were also compared in their ability to displace 125I‐mouse NGF from low‐affinity NGF receptors on rat pheochromocytoma PC12 cells. Similar displacement curves and values were obtained for each NGF protein, indicating that structural differences among these molecules do not affect low‐affinity binding to NGF receptors. Biological activities were studied by the ability of the conditioned media to promote neurite outgrowth from explants of 9 chick sympathetic ganglia and from PC12 ceils. Although the rat system showed a slight preference for the homologous molecule, the morphological changes, dose‐response curves, and maximal stimulation values obtained with the different NGFs were practically indistinguishable in the chicken bioassay. The observed differences and similarities among the three NGF proteins are discussed in the context of their evolutionary relationship and their potential therapeutic applications.
Striatal Restricted Adenosine A2 Receptor (RDC8) Is Expressed by Enkephalin but Not by Substance P Neurons: An In Situ Hybridization Histochemistry Study
Authors: Schiffmann Serge N. , Jacobs Olivier , Vanderhaeghen Jean‐Jacques 
Published: October 2006

AbstractRDC8 has been recently cloned and characterized as an adenosine A2 receptor. This receptor is expressed exclusively by medium‐sized neurons of the striatum as demonstrated by in situ hybridization. We have now studied the relationship of this receptor with three major components of the rat caudate‐putamen: enkephalin, substance P, and choline acetyltransferase. Our results demonstrate that the adenosine A2 receptor is expressed exclusively by the enkephalinergic striatal subpopulation but not by the substance P‐containing or cholinergic neurons.