bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of expression of sulfoglucuronyl carbohydrate (HNK‐1), Amphoterin and RAGE in retinoic acid‐differentiated P19 embryonal carcinoma cells
Authors: Chou Denise K. H. , Henion Timothy R. , Jungalwala Firoze B. 
Published: July 2003

AbstractHNK‐1 antibody reactive sulfoglucuronyl carbohydrate (SGC) and SSEA‐1 antibody reactive Lewis X (Lex) epitope are expressed on several glycolipids, glycoproteins, and proteoglycans of the nervous system and have been implicated in cell–cell recognition, neurite outgrowth, and/or neuronal migration during development. Interaction of SGC with its binding protein Amphoterin and interaction of Amphoterin with a cell‐signaling molecule, receptor for advance glycation end product (RAGE) have been suggested to regulate neurite outgrowth and neuronal migration. The regulation of expression of SGC, Lex, Amphoterin, and RAGE was studied in embryonal carcinoma P19 cells after treatment with retinoic acid (RA). The untreated proliferating P19 cells strongly expressed the Lex epitope, which was mostly due to Lex‐glycoproteins. P19 cells, when differentiated into neuron‐like cells by RA, did not express the Lex epitope, but expressed increasing levels of SGC, with time in culture. Quantitative biochemical analyses showed that in the P19 cells after RA treatment, the amount of SGC‐glycoproteins increased at a significantly higher level than sulfoglucuronyl glycolipid‐1 (SGGL‐1). The increase in the levels of SGGL‐1 was due to 16‐fold upregulation in the activity of lactosylceramide: N‐acetylglucosaminyl‐transferase (Lc3 synthase), which synthesizes the key intermediate lactotriosylceramide (Lc3Cer), for lacto‐ and neolacto‐glycolipids. The large increase in the activity of Lc3 synthase appeared to regulate the levels of other neolacto glycolipids, such as Lc3Cer, nLc4Cer, nLc6Cer, disialosyl‐nLc4Cer (LD1), and Lex‐glycolipids. Strong upregulation of glucuronyl‐transferase and modest twofold enhancement in the activity of the glucuronyl‐sulfotransferase, which catalyze the final steps in the SGC synthesis, also would account for the large increase in the synthesis SGC‐glycoproteins. RA also upregulated the synthesis of Amphoterin and RAGE in P19 cells. SGC, RAGE, and Amphoterin were co‐localized in the RA‐differentiated neurons. The initiation of neurite outgrowth along with co‐ordinated upregulation of Amphoterin, RAGE, SGC‐glycoproteins, and SGGLs in RA‐treated P19 cells support the hypothesis that these molecules are involved in the neuronal process formation.
Diabetic neuropathy: inhibitory G protein dysfunction involves PKC‐dependent phosphorylation of Goα
Authors: Shangguan Yu , Hall Karen E. , Neubig Richard R. , Wiley John W. 
Published: July 2003

AbstractWe examined the hypothesis that decreased inhibitory G protein function in diabetic neuropathy is associated with increased protein kinase C (PKC)‐dependent phosphorylation of the Goα subunit. Streptozotocin‐induced diabetic rats were studied between 4 and 8 weeks after onset of diabetes and compared with aged‐matched healthy animals as controls. Opioid‐mediated inhibition of forskolin‐stimulated cyclic AMP was significantly less in dorsal root ganglia (DRGs) from diabetic rats compared with controls. Activation of PKC in DRGs from control rats was associated with a significant decrease in opioid‐mediated inhibition of forskolin‐stimulated cyclic AMP that was similar to the decrease in inhibition observed in DRGs from diabetic rats. Both basal and PKC‐mediated labeling of Goα with 32Pi was significantly less in DRGs from diabetic rats, supporting increased endogenous PKC‐dependent phosphorylation of Goα. Probing of immunoprecipitated Goα with an anti‐phospho‐serine/threonine specific antibody revealed a significant increase in baseline phosphorylation in diabetic DRGs. Activation of PKC produced a significant increase in phosphorylation in control DRGs but no significant increase in Goα in diabetic DRGs. Phosphorylation of PKC‐α was increased, PKC‐βII was unchanged and PKC‐δ decreased in diabetic DRGs. These results suggest that diminished inhibitory G protein function observed in DRGs neurons from diabetic rats involves an isoform‐specific PKC‐dependent pathway.
Involvement of mitochondrial K+ release and cellular efflux in ischemic and apoptotic neuronal death
Authors: Liu Dong , Slevin John R. , Lu Chengbiao , Chan Sic L. , Hansson Magnus , Elmér Eskil , Mattson Mark P. 
Published: July 2003

AbstractWe measured and manipulated intracellular potassium (K+) fluxes in cultured hippocampal neurons in an effort to understand the involvement of K+ in neuronal death under conditions of ischemia and exposure to apoptotic stimuli. Measurements of the intracellular K+ concentration using the fluorescent probe 1,3‐benzenedicarboxylic acid, 4,4′‐[1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane‐7,16‐diylbis(5‐methoxy‐6,2‐benzofurandiyl)]bis‐, tetrakis [(acetyloxy) methyl] ester (PBFI) revealed that exposure of neurons to cyanide (chemical hypoxia), glutamate (excitotoxic insult) or staurosporine (apoptotic stimulus) results in efflux of K+ and cell death. Treatment of neurons with 5‐hydroxydecanoate (5HD), an inhibitor of mitochondrial K+ channels, reduced K+ fluxes in neurons exposed to each insult and increased the resistance of the cells to death. K+ efflux was attenuated, levels of oxyradicals were decreased, mitochondrial membrane potential was stabilized and release of cytochrome c from mitochondria was attenuated in neurons treated with 5HD. K+ was rapidly released into the cytosol from mitochondria when neurons were exposed to the K+ channel opener, diazoxide, or to the mitochondrial uncoupler, carbonyl cyanide 4(trifluoromethoxy)phenylhydrazone (FCCP), demonstrating that the intramitochondrial K+ concentration is greater than the cytosolic K+ concentration. The release of K+ from mitochondria was followed by efflux through plasma membrane K+ channels. In vivo studies showed that 5HD reduces ischemic brain damage without affecting cerebral blood flow in a mouse model of focal ischemic stroke. These findings suggest that intracellular K+ fluxes play a key role in modulating neuronal oxyradical production and cell survival under ischemic conditions, and that agents that modify K+ fluxes may have therapeutic benefit in stroke and related neurodegenerative conditions.
Central catecholamine depletion inhibits peripheral lymphocyte responsiveness in spleen and blood
Authors: Pacheco‐López Gustavo , Niemi Maj‐Britt , Kou Wei , Bildhäuser Andre , Gross Claus M. , Goebel Marion U. , Del Rey Adriana , Besedovsky Hugo O. , Schedlowski Manfred 
Published: July 2003

AbstractExperimental and clinical evidence has demonstrated extensive communication between the CNS and the immune system. To analyse the role of central catecholamines in modulating peripheral immune functions, we injected the neurotoxin 6‐hydroxydopamine (6‐OHDA) i.c.v. in rats. This treatment significantly reduced brain catecholamine content 2, 4 and 7 days after injection, and in the periphery splenic catecholamine levels were reduced 4 days after treatment. Central catecholamine depletion induced an inhibition of splenic and blood lymphocyte proliferation and splenic cytokine production and expression (interleukin‐2 and interferon‐γ) 7 days after injection. In addition, central treatment with 6‐OHDA reduced the percentage of spleen and peripheral blood natural killer (CD161 +) cells, and T‐cytotoxic (CD8 +) cells in peripheral blood. The reduction in splenocyte proliferation was not associated with a glucocorticoid alteration but was completely abolished by prior peripheral sympathectomy. These data demonstrate a crucial role of central and peripheral catecholamines in modulating immune function.
Oxidative phosphorylation by in situ synaptosomal mitochondria from whole brain of young and old rats
Authors: Joyce O. J. P. , Farmer M. K. , Tipton K. F. , Porter R. K. 
Published: July 2003

AbstractSynaptosomes, isolated from the whole brain of young (3 months) and old (24 months) rats were used to study the major bioenergetic systems of neuronal mitochondria in situ, within the synaptosome. Approximately 85% of the resting oxygen consumption of synaptosomes from both young and old rats was a result of proton leak (and possibly other ion cycling) across the mitochondrial inner membrane. There were no significant differences between synaptosomes from the young and old rats in the kinetic responses of the substrate oxidation system, the mitochondrial proton leak and the phosphorylation system to changes in the proton electrochemical gradient. Flux control coefficients of 0.71, 0.27 and 0.02 were calculated for substrate oxidation system, phosphorylation system and the proton leak, respectively, at maximal ATP producing capacity in synaptosomes from young animals. The corresponding values calculated for synaptosomes from old animals were 0.53, 0.43 and 0.05. Thus substrate oxidation had greatest control over oxygen consumption at maximal phosphorylating capacity for synaptosomes from whole brain, with proton leak, having little control under maximal ATP producing capacity. The uncoupled rate of oxygen consumption, in the presence of the mitochondrial uncoupler, carbonyl cyanide p‐trifluoromethoxyphenylhydrazone (FCCP), was significantly lower (p = 0.0124) in synaptosomes from old rats (6.08 ± 0.42, n = 11) when compared with those from the young rats (7.87 ± 0.48, n = 8). Thus, there is an impaired flux through the substrate oxidation system is synaptosomes from old rats, as compared to synaptosomes from the young animals. These in situ results may have important implications for the interpretation of theories that age‐dependent impairment of mitochondrial energy production may result in increased susceptibility to neurodegeneration.
The structure of neuromelanin as studied by chemical degradative methods
Authors: Wakamatsu Kazumasa , Fujikawa Kenichi , Zucca Fabio A. , Zecca Luigi , Ito Shosuke 
Published: July 2003

AbstractThe biosynthesis, structure and function of neuromelanin (NM), the dark brown melanin‐like pigment present in the substantia nigra (SN), are not well characterized, in spite of the possible involvement of NM in the etiology and pathogenesis of Parkinson's disease. NM was isolated from the SN of five non‐Parkinsonian human brains. NM and synthetic melanins, employed as models, were characterized by chemical analysis. Alkaline hydrogen peroxide (H2O2) oxidation of NM generated four degradation products, pyrrole‐2,3‐dicarboxylic acid (PDCA), pyrrole‐2,3,5‐tricarboxylic acid (PTCA), thiazole‐4,5‐dicarboxylic acid (TDCA) and thiazole‐2,3,5‐tricarboxylic acid (TTCA), whose ratios, especially the TTCA to PDCA ratio, indicate that NM is derived mostly from dopamine (DA) with 25% incorporation of cysteine (Cys) in the form of a benzothiazine structure. Hydriodic acid (HI) reductive hydrolysis of NM yielded 4‐amino‐3‐hydroxyphenylethylamine (4‐AHPEA) as a marker of cysteinyldopamine (CysDA)‐derived units. The 4‐AHPEA to PDCA ratio indicates a 21% incorporation of CysDA‐derived units into NM. These degradative experiments also suggest that DOPA is not incorporated into NM to a significant extent (approximately 6% the level of DA). It is concluded that the TTCA to PDCA ratio is a useful indicator of CysDA‐derived units in NM, and NM consists mainly of DA‐melanin with some contribution from CysDA‐melanin. The involvement of DA and CysDA as building blocks of NM demonstrates the detoxifying role of NM synthesis, since it prevents the intraneuronal accumulation of DA and CysDA, which would cause toxic effects.
Mitochondrial peroxiredoxin‐3 protects hippocampal neurons from excitotoxic injury in vivo
Authors: Hattori Fumiyuki , Murayama Norihito , Noshita Takafumi , Oikawa Shinzo 
Published: July 2003

AbstractMitochondria are involved in excitotoxic damage of nerve cells. Following the breakdown of the calcium‐buffering ability of mitochondria, mitochondrial calcium overload induces reactive oxygen species (ROS) bursts that produce free radicals and open permeability transition pores, ultimately leading to neuronal cell death. In the present study, we focused on a mitochondrial antioxidant protein, peroxiredoxin‐3 (Prx‐3), to investigate the mechanism by which toxic properties of ROS were up‐regulated in mitochondria of damaged nerve cells. Immunohistochemical analysis revealed that Prx‐3 protein exists in mitochondria of rat hippocampus, whereas we found a significant decrease in Prx‐3 mRNA and protein levels associated with an increase in nitrated proteins in the rat hippocampus injured by microinjection of ibotenic acid. Furthermore, in vivo adenoviral gene transfer of Prx‐3 completely inhibited protein nitration and markedly reduced gliosis, a post‐neuronal cell death event. Since mitochondrial Prx‐3 seems to be neuroprotective against oxidative insults, our findings suggest that Prx‐3 up‐regulation might be a useful novel approach for the management of neurodegenerative diseases.
Evidence for functional adenosine A3 receptors in microglia cells
Authors: Hammarberg Christian , Schulte Gunnar , Fredholm Bertil B. 
Published: July 2003

AbstractAdenosine exerts its effects through four subtypes of G‐protein‐coupled receptors (GPCRs): adenosine A1 and A3 receptors (A3R), which generally couple to Gi proteins and adenosine A2A and A2B receptors that activate Gs proteins. Though there is evidence for the expression of mRNA for the A3R in the central nervous system, evidence for functional receptors has depended on drugs with uncertain specificity. Here, we show that A3Rs mediating functional responses are present in microglia cells. By selectively stimulating the A3R in both primary mouse microglia cells and the N13 microglia cell line with the agonist Cl‐IB‐MECA, we have found a biphasic, partly Gi protein‐dependent influence on the phosphorylation of the extracellular signal‐regulated protein kinase 1/2 (ERK1/2). ERK1/2 activation was assessed by immunoblotting with phospho‐specific antibodies. The involvement of the A3R in Cl‐IB‐MECA‐induced ERK1/2 phosphorylation was confirmed by demonstrating that those effects are absent in primary mouse microglia cells isolated from mice lacking the gene for the A3R.
Collapsin response mediator protein‐2 accelerates axon regeneration of nerve‐injured motor neurons of rat
Authors: Suzuki Yasuhiro , Nakagomi Saya , Namikawa Kazuhiko , Kiryu‐Seo Sumiko , Inagaki Naoyuki , Kaibuchi Kozo , Aizawa Hitoshi , Kikuchi Kenjiro , Kiyama Hiroshi 
Published: July 2003

AbstractThe rat collapsin response mediator protein‐2 (CRMP‐2) is a member of CRMP family (CRMP‐1–5). The functional consequence of CRMP‐2 during embryonic development, particularly in neurite elongation, is relatively understood; however, the role in nerve regeneration is unclear. Here we examined the role of CRMP‐2 during nerve regeneration using rat hypoglossal nerve injury model. Among the members, CRMP‐1, CRMP‐2, CRMP‐5 mRNA expressions increased after nerve injury, whereas CRMP‐3 and CRMP‐4 mRNA did not show any significant change. In the N1E‐115 cells, CRMP‐2 has the most potent neurite elongation activity among the CRMP family members. In dorsal root ganglion (DRG) organ culture, CRMP‐2 overexpression by adenoviral vector demonstrated substantial neurite elongation. On the other hand, CRMP‐2 (ΔC381), which acts as a dominant negative form of CRMP‐2, inhibited neurite formation. Collectively, it would be plausible that CRMP‐2 has potent nerve regeneration activity after nerve injury. We therefore examined whether CRMP‐2 overexpression in the injured hypoglossal motor neurons accelerates nerve regeneration. A retrograde‐tracer, Fluoro‐Gold (FG), was used to evaluate the number of reprojecting motor neurons after nerve injury. CRMP‐2‐overexpressing motor neurons demonstrated the accelerated reprojection. The present study suggests that CRMP‐2 has potent neurite elongation activity in nerve regeneration in vivo.
A complex signaling cascade links the serotonin2A receptor to phospholipase A2 activation: the involvement of MAP kinases
Authors: Kurrasch‐Orbaugh Deborah M. , Parrish Jason C. , Watts Val J. , Nichols David E. 
Published: July 2003

AbstractPrevious studies in our laboratory have shown that in NIH3T3–5HT2A cells, 5‐HT‐induced AA release is PLA2‐coupled and independent of 5‐HT2A receptor‐mediated PLC activation. Although 5‐HT2A receptor‐mediated PLC activation is known to be Gαq‐coupled, much less is understood about 5‐HT2A receptor‐mediated PLA2 activation. Therefore, the studies presented here were aimed at elucidating the signal transduction pathway linking stimulation of the 5‐HT2A receptor to PLA2 activation. By employing various selective inhibitors, toxins, and antagonistic peptide constructs, we propose that the 5‐HT2A receptor can couple to PLA2 activation through two parallel signaling cascades. Initial experiments were designed to examine the role of pertussis toxin‐sensitive G proteins, namely Gαi/o, as well as pertussis toxin‐insensitive G proteins, namely Gα12/13, in 5‐HT‐induced AA release. Furthermore, inactivation of both Gβγ heterodimers and Rho proteins resulted in decreased agonist‐induced AA release, without having any effect on PLC‐IP accumulation. We also demonstrated 5‐HT2A receptor‐mediated phosphorylation of ERK1,2 and p38. Moreover, pretreatment with selective ERK1,2 and p38 inhibitors resulted in decreased 5‐HT‐induced AA release. Taken together, these results suggest that the 5‐HT2A receptor expressed in NIH3T3 cells can couple to PLA2 activation though a complex signaling mechanism involving both Gαi/o‐associated Gβγ‐mediated ERK1,2 activation and Gα12/13‐coupled, Rho‐mediated p38 activation.
The role of the RE1 element in activation of the NR1 promoter during neuronal differentiation
Authors: Bai Guang , Zhuang Zhiye , Liu Anguo , Chai Yanfeng , Hoffman Peter W. 
Published: July 2003

AbstractTo understand the genetic mechanism controlling the expression of the NMDA subtype of glutamate receptors during neuronal differentiation, we studied activation of the N‐methyl‐D‐aspartate receptor subunit 1 (NR1) gene and the role of the repressor element‐1 (RE1) element in NR1 promoter activation. Following neuronal differentiation of P19 embryonic carcinoma cells, the NR1 transcription rate and mRNA level were significantly increased, while the nuclear level of the repressor RE1 silencing transcription factor (REST)/neuron‐restriction silencer factor (NRSF) was reduced. Nuclear REST/NRSF from undifferentiated cells formed a large complex with the NR1 RE1 element. While this complex was significantly reduced after the differentiation, REST/NRSF from differentiated cells formed a new, faster migrating complex. In transient transfections, deletion of the RE1 element increased activity of the 5.4‐kb NR1 promoter sixfold in undifferentiated cells, but only induced approximately 1.4‐fold increase in differentiated cells. Forced expression of REST/NRSF in differentiated cells suppressed the promoter, while forced expression of a dominant‐negative REST/NRSF induced promoter activity as well as the mRNA of the NR1 gene in undifferentiated cells. In stable transfectants, the wild‐type promoter showed a robust increase in activity following differentiation in a pattern similar to the NR1 mRNA increase. Conversely, the promoter lacking the RE1 element showed only a moderate increase. Our data suggest that the NR1 gene up‐regulation during neuronal differentiation is controlled by its promoter activation, which is largely determined by the interaction between the RE1 element and the repressor REST/NRSF.
Neurotoxins in the Neurobiology of Pain
Authors: Silberstein Stephen D. 
Published: July 2003

Migraine is a common, chronic, incapacitating, neurovascular disorder that affects an estimated 12% of the population. Understanding the basic mechanisms of pain is important when treating patients with chronic pain disorders.Pain, an unpleasant sensory and emotional experience, is usually triggered by stimulation of peripheral nerves and often associated with actual or potential tissue damage. Peripheral nerve fibers transmit pain signals from the periphery toward the spinal cord or brain stem. The different diameter pain fibers (A and C) vary in the speed of conduction and the type of pain transmitted (eg, sharp versus dull). When stimulated, peripheral pain fibers carrying sensory input from the body enter at different layers of the dorsal horn, which is then propagated toward the thalamus via the spinothalamic tract within the spinal cord. Conversely, sensory input from the face does not enter the spinal cord but enters the brain stem via the trigeminal nerve.This review describes in detail the neurobiological mechanisms and pathways for pain sensation, with a focus on migraine pain.
Evidence for Antinociceptive Activity of Botulinum Toxin Type A in Pain Management
Authors: Aoki K. Roger 
Published: July 2003

The neurotoxin, botulinum toxin type A, has been used successfully, in some patients, as an analgesic for myofascial pain syndromes, migraine, and other headache types. The toxin inhibits the release of the neurotransmitter, acetylcholine, at the neuromuscular junction thereby inhibiting striated muscle contractions. In the majority of pain syndromes where botulinum toxin type A is effective, inhibiting muscle spasms is an important component of its activity. Even so, the reduction of pain often occurs before the decrease in muscle contractions suggesting that botulinum toxin type A has a more complex mechanism of action than initially hypothesized. Current data points to an antinociceptive effect of botulinum toxin type A that is separate from its neuromuscular activity. The common biochemical mechanism, however, remains the same between botulinum toxin type A's effect on the motor nerve or the sensory nerve: enzymatic blockade of neurotransmitter release. The antinociceptive effect of the toxin was reported to block substance P release using in vitro culture systems.1The current investigation evaluated the in vivo mechanism of action for the antinociceptive action of botulinum toxin type A. In these studies, botulinum toxin type A was found to block the release of glutamate. Furthermore, Fos, a product of the immediate early gene, c‐fos, expressed with neuronal stimuli was prevented upon peripheral exposure to the toxin.These findings suggest that botulinum toxin type A blocks peripheral sensitization and, indirectly, reduces central sensitization. The recent hypothesis that migraine involves both peripheral and central sensitization may help explain how botulinum toxin type A inhibits migraine pain by acting on these two pathways. Further research is needed to determine whether the antinociceptive mechanism mediated by botulinum toxin type A affects the neuronal signaling pathways that are activated during migraine.