bluuebunny/crossref_metadata_2025_split huggingface dataset:
Facilitation of α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate receptor transmission in the suprachiasmatic nucleus by aniracetam enhances photic responses of the biological clock in rodents
Authors: Moriya Takahiro , Ikeda Masayuki , Teshima Koji , Hara Reiko , Kuriyama Koji , Yoshioka Tohru , N. Allen Charles , Shibata Shigenobu 
Published: July 2010

AbstractThis study was designed to test whether the α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA) receptor‐facilitating drug, aniracetam, could potentiate photic responses of the biological clock in the suprachiasmatic nucleus (SCN) of rodents. Using the whole‐cell patch technique, we first demonstrated that AMPA currents elicited by either local AMPA application or optic chiasm stimulation were augmented by aniracetam in the neurons of the SCN. The AMPA application‐elicited increase of intracellular Ca2+ concentration in SCN slices was also enhanced by aniracetam treatment. The systemic injection of aniracetam dose‐dependently (10–100 mg/kg) potentiated the phase delay in behavioral rhythm induced by brief light exposure of low intensity (3 lux) but not high intensity (10 or 60 lux) during early subjective night. Under the blockade of NMDA receptors by (+) MK801, aniracetam failed to potentiate a light (3 lux)‐induced phase delay in behavioral rhythm. Aniracetam increased the photic induction of c‐Fos protein in the SCN that was elicited by low intensity light exposure (3 lux). These results suggest that AMPA receptor‐mediated responses facilitated by aniracetam can explain enhanced photic responses of the biological clock in the SCN of rodents.
Neuronal uptake and metabolism of glycerol and the neuronal expression of mitochondrial glycerol‐3‐phosphate dehydrogenase
Authors: Nguyen Nga Huynh Tran , Bråthe Anders , Hassel Bjørnar 
Published: July 2010

AbstractGlycerol is effective in the treatment of brain oedema but it is unclear if this is due solely to osmotic effects of glycerol or whether the brain may metabolize glycerol. We found that intracerebral injection of [14C]glycerol in rat gave a higher specific activity of glutamate than of glutamine, indicating neuronal metabolism of glycerol. Interestingly, the specific activity of GABA became higher than that of glutamate. NMR spectroscopy of brains of mice given 150 µmol [U‐13C]glycerol (0.5 m i.v.) confirmed this predominant labelling of GABA, indicating avid glycerol metabolism in GABAergic neurones. Uptake of [14C]glycerol into cultured cerebellar granule cells was inhibited by Hg2+, suggesting uptake through aquaporins, whereas Hg2+ stimulated glycerol uptake into cultured astrocytes. The neuronal metabolism of glycerol, which was confirmed in experiments with purified synaptosomes and cultured cerebellar granule cells, suggested neuronal expression of glycerol kinase and some isoform of glycerol‐3‐phosphate dehydrogenase. Histochemically, we demonstrated mitochondrial glycerol‐3‐phosphate dehydrogenase in neurones, whereas cytosolic glycerol‐3‐phosphate dehydrogenase was three to four times more active in white matter than in grey matter, reflecting its selective expression in oligodendroglia. The localization of mitochondrial and cytosolic glycerol‐3‐phosphate dehydrogenases in different cell types implies that the glycerol‐3‐phosphate shuttle is of little importance in the brain.
Regulation of the glutamate transporter EAAT1 by the ubiquitin ligase Nedd4‐2 and the serum and glucocorticoid‐inducible kinase isoforms SGK1/3 and protein kinase B
Authors: Boehmer Christoph , Henke Guido , Schniepp Roman , Palmada Monica , Rothstein Jeffrey D. , Bröer Stefan , Lang Florian 
Published: July 2010

AbstractSurface expression of the glial glutamate transporter EAAT1 is stimulated by insulin‐like growth factor 1 through activation of phosphatidylinositol‐3‐kinase. Downstream targets include serum and glucocorticoid‐sensitive kinase isoforms SGK1, SGK2 and SGK3, and protein kinase B. SGK1 regulates Nedd4‐2, a ubiquitin ligase that prepares cell membrane proteins for degradation. To test whether Nedd4‐2, SGK1, SGK3 and protein kinase B regulate EAAT1, cRNA encoding EAAT1 was injected into Xenopus oocytes with or without additional injection of wild‐type Nedd4‐2, constitutively active S422DSGK1, inactive K127NSGK1, wild‐type SGK3 and/or constitutively active T308D,S473DPKB. Glutamate induces a current in Xenopus oocytes expressing EAAT1, but not in water‐injected oocytes, which is decreased by co‐expression of Nedd4‐2, an effect reversed by additional co‐expression of S422DSGK1, SGK3 and T308D,S473DPKB, but not K127NSGK1. Site‐directed mutagenesis of the SGK1 phosphorylation sites in the Nedd4‐2 protein (S382A,S468ANedd4‐2) and in the EAAT1 protein (T482AEAAT1, T482DEAAT1) significantly blunts the effect of S422DSGK1. Moreover, the current is significantly larger in T482DEAAT1‐ than in T482AEAAT1‐expressing oocytes, indicating that a negative charge mimicking phosphorylation at T482 increases transport. The experiments reveal a powerful novel mechanism that regulates the activity of EAAT1. This mechanism might participate in the regulation of neuronal excitability and glutamate transport in other tissues.
Tumor necrosis factor‐α at the crossroads of neuronal life and death during HIV‐associated dementia
Authors: Saha Ramendra N. , Pahan Kalipada 
Published: July 2010

AbstractHuman immunodeficiency type‐1 (HIV‐1) infection is known to cause disorders of the CNS, including HIV‐associated dementia (HAD). It is suspected that tumor necrosis factor‐α (TNF‐α) released by infected microglia and macrophages play a role in neuronal injury seen in HAD patients. Accordingly, studies suggest that the level of TNF‐α mRNA increases with increasing severity of dementia in patients, and that inhibitors of TNF‐α release reduces neuronal injury in murine model of HAD. However, the exact role of TNF‐α in relation to neuronal dysfunction is a matter of ongoing debate. One school of thought hails TNF‐α as the inducer and mediator of neurodegeneration and their evidence suggest that TNF‐α kill neurons directly by recruiting caspases or may kill indirectly by various means. In sharp contrast to this, another concept theory envisages a role for TNF‐α in negotiating neuroprotection during HAD. The current compilation examines these contradictory concepts, and evaluates their efficacy in the light of TNF‐α signaling. It also attempts to elaborate the current consensus outlook of TNF‐α's role during HAD.
Erasure of kinase phosphorylation in astrocytes during oxygen–glucose deprivation is controlled by ATP levels and activation of phosphatases
Authors: Yung Hong Wa , Tolkovsky Aviva M. 
Published: July 2010

AbstractWe have examined the relationship between adenosine triphosphate (ATP) concentration and loss of maintenance of kinase‐signalling cascades in primary cortical astrocytes during oxygen–glucose deprivation (OGD) as this may constitute an irreversible step that commits astrocytes to cell death. We report that the phosphorylation of Akt, ERK, JNK and p38 kinases, whose activities depend on serine, threonine and tyrosine phosphorylation, were all increased during OGD. All these phosphorylations were reduced to below detection limits when ATP levels were less than 10% of normal levels. Using ERK and Akt as representative examples, we show that this erasure is not irreversible as both ERK and Akt phosphorylations can be partially restored by addition of glucose under anoxic conditions. We further investigated whether OGD caused any change in phosphatase activity. The PP1/PP2A phosphatase inhibitors okadaic acid and caliculyn A, but not cyclosporine A, delayed the removal of ERK and Akt phosphorylation under OGD. By comparing the extent of phosphorylation increase under OGD and normoxic conditions, we calculate that phosphatase activity was increased by approximately 3.6‐fold during OGD. These data show that ATP levels control an important checkpoint in kinase function, and that ATP levels may need to be considered when studies of kinase function in relation to OGD are conducted.
Puromycin selectively increases mdr1a expression in immortalized rat brain endothelial cell lines
Authors: Demeuse P. , Fragner P. , Leroy‐Noury C. , Mercier C. , Payen L. , Fardel O. , Couraud P. ‐O. , Roux F. 
Published: July 2010

AbstractThe blood–brain barrier (BBB) plays an important role in controlling the passage of molecules from blood to brain extracellular fluid. The multidrug efflux pump P‐glycoprotein (P‐gp) is highly expressed in the luminal membrane of brain endothelium and contributes to the formation of a functional barrier to lipid‐soluble drugs such as anticancer agents. The mdr1a P‐gp‐encoding gene is exclusively expressed in the rodent BBB. Primary cultures of rat brain endothelial cells and GP8.3 cells showed a dramatic decrease in mdr1a mRNA level and some expression of mdr1b mRNA. GPNT cells, derived from GP8.3 cells after transfection with a puromycin resistance gene, were chronically treated with 5 µg/mL puromycin, a P‐gp substrate. Compared with rat brain endothelial cells and GP8.3 cells, GPNT cells exhibited a very high level of expression of mdr1a mRNA together with a moderate level of mdr1b mRNA expression. Accordingly, P‐gp expression and activity were strongly increased. When GP8.3 and puromycin‐starved GPNT cells were treated with puromycin, mdr1a expression was selectively increased. High expression of mdr1a mRNA in GPNT cells may thus be related to the chronic treatment with puromycin. We conclude that GPNT cells may be used as a valuable ratin vitromodel for studying the regulation of mdr1a expression at the BBB level.
Determination of the oxidation states of manganese in brain, liver, and heart mitochondria
Authors: Gunter Thomas E. , Miller Lisa M. , Gavin Claire E. , Eliseev Roman , Salter Jason , Buntinas Linas , Alexandrov Andrei , Hammond Sean , Gunter Karlene K. 
Published: July 2010

AbstractExcess brain manganese can produce toxicity with symptoms that resemble those of Parkinsonism and causes that remain elusive. Manganese accumulates in mitochondria, a major source of superoxide, which can oxidize Mn2+to the powerful oxidizing agent Mn3+. Oxidation of important cell components by Mn3+has been suggested as a cause of the toxic effects of manganese. Determining the oxidation states of intramitochondrial manganese could help to identify the dominant mechanism of manganese toxicity. Using X‐ray absorbance near edge structure (XANES) spectroscopy, we have characterized the oxidation state of manganese in mitochondria isolated from brain, liver, and heart over concentrations ranging from physiological to pathological. Results showed that (i) spectra from different model manganese complexes of the same oxidation state were similar to each other and different from those of other oxidation states and that the position of the absorption edge increases with oxidation state; (ii) spectra from intramitochondrial manganese in isolated brain, heart and liver mitochondria were virtually identical; and (iii) under these conditions intramitochondrial manganese exists primarily as a combination of Mn2+complexes. No evidence for Mn3+was detected in samples containing more than endogenous manganese levels, even after incubation under conditions promoting reactive oxygen species (ROS) production. While the presence of Mn3+complexes cannot be proven in the spectrum of endogenous mitochondrial manganese, the shape of this spectrum could suggest the presence of Mn3+near the limit of detection, probably as MnSOD.
Ceramide pathways modulate ethanol‐induced cell death in astrocytes
Authors: Pascual María , Valles Soraya L. , Renau‐Piqueras Jaime , Guerri Consuelo 
Published: July 2010

AbstractWe showed previously that alcohol exposure duringin vivobrain development induced astroglial damage and caused cell death. Because ceramide modulates a number of biochemical and cellular responses to stress, including apoptosis, we now investigate whether ethanol‐induced cell death in astrocytes is mediated by ceramide signalling pathways triggering apoptosis. Here we show that both ethanol and ceramide are able to induce apoptotic death in cultured astrocytes, in a dose‐dependent manner, and that C2‐ceramide addition potentiates the apoptotic effects of ethanol. Cell death induced by ethanol is associated with stimulation of neutral and acidic sphingomyelinase (SMase) and ceramide generation, as well as with activation of stress‐related kinases, c‐Jun N‐terminal kinase (JNK), p38 mitogen‐activated protein kinase (p38) and extracellular signal‐regulated kinase (ERK) pathways. We also provide evidence for the participation of JNK and p38 in ethanol‐induced cell death, because pharmacological inhibitors of these kinases largely prevent the apoptosis induced by ethanol or by ethanol and C2‐ceramide. Furthermore, we show that ethanol‐induced ERK activation triggers the stimulation of cyclo‐oxygenase‐2 (COX‐2) and the release of prostaglandin E2, and that blockade of the mitogen‐activated protein kinase kinase (MEK)/ERK pathway by PD98059 abolishes the up‐regulation of COX‐2 induced by ethanol plus ceramide, and decreases the ethanol‐induced apoptosis. These results strongly suggest that ethanol is able to stimulate the SMase–ceramide pathway, leading to the activation of signalling pathways implicated in cell death. These findings provide an insight into the mechanisms involved in ethanol‐induced astroglial cell death during brain development.
Oligomerization and neurotoxicity of the amyloid ADan peptide implicated in familial Danish dementia
Authors: Gibson Gillian , Gunasekera Nicola , Lee Maria , Lelyveld Victor , El‐Agnaf Omar M. A. , Wright Andrew , Austen Brian 
Published: July 2010

AbstractFamilial Danish dementia (FDD) is a rare neurodegenerative disorder, which is pathologically characterized by widespread cerebral amyloid angiopathy, parenchymal protein deposits and neurofibrillary degeneration. FDD is associated with mutation in the BRI gene. In FDD a decamer duplication between codons 265 and 266 in the 3′ region of the BRI gene originates an amyloid peptide named ADan, 11 residues longer than the wild‐type peptide produced from the normal BRI gene. ADan deposits have been found widely distributed in the CNS of FDD cases. The deposits of ADan are predominantly non‐fibrillar aggregates. We show here that synthetic ADan forms oligomers in vitro, seen by Tricine–PAGE and gel filtration, and higher aggregates, which are seen by atomic force spectroscopy and electron microscopy as carrot‐shaped objects that bunch together. Here we report that oligomeric ADan is toxic to neuronal cell lines. We find that the soluble non‐fibrillar oligomeric species of both the reduced and oxidized forms of ADan are toxic. These results support the idea that the non‐fibrillar soluble aggregates are the pathogenic species, which may play a central role in the pathogenesis of FDD, and imply that similar mechanism may also be involved in other neurodegenerative diseases associated with amyloid deposits.
Subunit composition and quantitative importance of GABAAreceptor subtypes in the cerebellum of mouse and rat
Authors: Pöltl Angelika , Hauer Birgit , Fuchs Karoline , Tretter Verena , Sieghart Werner 
Published: July 2010

AbstractIn cerebellum, 13 different GABAAreceptor subunits are expressed. The number of different receptor subtypes formed in this tissue, their subunit composition and their quantitative importance so far has not been determined. In the present study, immunodepletion by immunoaffinity chromatography, as well as immunoprecipitation and western blot analysis was performed using 13 different subunit‐specific antibodies to provide an overview on the subunit composition and abundance of GABAAreceptor subtypes in mouse and rat cerebellum. Results obtained indicate that α1βxγ2, α1α6βxγ2, α6βxγ2, α6βxδ and α1α6βxδ are the major GABAAreceptor subtypes present in the cerebellum. In addition, small amounts of α1βxδ receptors and a series of minor receptor subtypes containing α2, α3, α4, α5, γ1or γ3subunits are also present in the cerebellum. Whereas the abundance of α1α6βxγ2, α6βxδ and α1α6βxδ receptors is different in mouse and rat cerebellum, that of other receptors is quite similar in these tissues. Data obtained for the first time provide an overview on the GABAAreceptor subtypes present in the cerebellum and represent the basis for further studies investigating changes in receptor expression and composition under pathological conditions.
Methamphetamine produces neuronal inclusions in the nigrostriatal system and in PC12 cells
Authors: Fornai Francesco , Lenzi Paola , Gesi Marco , Soldani Paola , Ferrucci Michela , Lazzeri Gloria , Capobianco Loredana , Battaglia Giuseppe , De Blasi Antonio , Nicoletti Ferdinando , Paparelli Antonio 
Published: July 2010

AbstractMice treated with the psychostimulant methamphetamine (MA) showed the appearance of intracellular inclusions in the nucleus of medium sized striatal neurones and cytoplasm of neurones of the substantia nigra pars compacta but not in the frontal cortex. All inclusions contained ubiquitin, the ubiquitin activating enzyme (E1), the ubiquitin protein ligase (E3‐like, parkin), low and high molecular weight heat shock proteins (HSP 40 and HSP 70). Inclusions found in nigral neurones stained for α‐synuclein, a proteic hallmark of Lewy bodies that are frequently observed in Parkinson's disease and other degenerative disorders. However, differing from classic Lewy bodies, MA‐induced neuronal inclusions appeared as multilamellar bodies resembling autophagic granules. Methamphetamine reproduced this effect in cultured PC12 cells, which offered the advantage of a simple cellular model for the study of the molecular determinants of neuronal inclusions. PC12 inclusions, similar to those observed in nigral neurones, were exclusively localized in the cytoplasm and stained for α‐synuclein. Time‐dependent experiments showed that inclusions underwent a progressive fusion of the external membranes and developed an electrodense core. Inhibition of dopamine synthesis by α‐methyl‐p‐tyrosine (αMpT), or administering the antioxidant S‐apomorphine largely attenuated the formation of inclusions in PC12 cells exposed to MA. Inclusions were again observed when αMpT‐treated cells were loaded with l‐DOPA, which restored intracellular dopamine levels.
Annonacin, a lipophilic inhibitor of mitochondrial complex I, induces nigral and striatal neurodegeneration in rats: possible relevance for atypical parkinsonism in Guadeloupe
Authors: Champy Pierre , Höglinger Günter U. , Féger Jean , Gleye Christophe , Hocquemiller Reynald , Laurens Alain , Guérineau Vincent , Laprévote Olivier , Medja Fadia , Lombès Anne , Michel Patrick P. , Lannuzel Annie , Hirsch Etienne C. , Ruberg Merle 
Published: July 2010

AbstractIn Guadeloupe, epidemiological data have linked atypical parkinsonism with fruit and herbal teas from plants of the Annonaceae family, particularly Annona muricata. These plants contain a class of powerful, lipophilic complex I inhibitors, the annonaceous acetogenins. To determine the neurotoxic potential of these substances, we administered annonacin, the major acetogenin of A. muricata, to rats intravenously with Azlet osmotic minipumps (3.8 and 7.6 mg per kg per day for 28 days). Annonacin inhibited complex I in brain homogenates in a concentration‐dependent manner, and, when administered systemically, entered the brain parenchyma, where it was detected by matrix‐associated laser desorption ionization – time of flight mass spectrometry, and decreased brain ATP levels by 44%. In the absence of evident systemic toxicity, we observed neuropathological abnormalities in the basal ganglia and brainstem nuclei. Stereological cell counts showed significant loss of dopaminergic neurones in the substantia nigra (− 31.7%), and cholinergic (− 37.9%) and dopamine and cyclic AMP‐regulated phosphoprotein (DARPP‐32)‐immunoreactive GABAergic neurones (− 39.3%) in the striatum, accompanied by a significant increase in the number of astrocytes (35.4%) and microglial cells (73.4%). The distribution of the lesions was similar to that in patients with atypical parkinsonism. These data are compatible with the theory that annonaceous acetogenins, such as annonacin, might be implicated in the aetiology of Guadeloupean parkinsonism and support the hypothesis that some forms of parkinsonism might be induced by environmental toxins.
Increased expression and processing of caspase‐12 after traumatic brain injury in rats
Authors: Larner Stephen F. , Hayes Ronald L. , McKinsey Deborah M. , Pike Brian R. , Wang Kevin K. W. 
Published: July 2010

AbstractTraumatic brain injury (TBI) disrupts tissue homeostasis resulting in pathological apoptotic activation. Recently, caspase‐12 was reported to be induced and activated by the unfolded protein response following excess endoplasmic reticulum (ER) stress. This study examined rat caspase‐12 expression using the controlled cortical impact TBI model. Immunoblots of fractionalized cell lysates found elevated caspase‐12 proform (∼60 kDa) and processed form (∼12 kDa), with peak induction observed within 24 h post‐injury in the cortex (418% and 503%, respectively). Hippocampus caspase‐12 proform induction peaked at 24 h post‐injury (641%), while processed form induction peaked at 6 h (620%). Semi‐quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) analysis confirmed elevated caspase‐12 mRNA levels after TBI. Injury severity (1.0, 1.2 or 1.6 mm compression) was associated with increased caspase‐12 mRNA expression, peaking at 5 days in the cortex (657%, 651% and 1259%, respectively) and 6 h in the hippocampus (435%, 451% and 460%, respectively). Immunohistochemical analysis revealed caspase‐12 induction in neurons in both the cortex and hippocampus as well as in astrocytes at the contusion site. This is the first report of increased expression of caspase‐12 following TBI. Our results suggest that the caspase‐12‐mediated ER apoptotic pathway may play a role in rat TBI pathology independent of the receptor‐ or mitochondria‐mediated apoptotic pathways.
Developmental changes in expression and subcellular localization of the DNA repair glycosylase, MYH, in the rat brain
Authors: Lee Heung‐Man , Hu Zhaoyong , Ma Huaxian , Greeley George H. , Wang Cheng , Englander Ella W. 
Published: July 2010

AbstractMammalian cells employ a network of DNA repair pathways. DNA repair is required during development to ensure accuracy of DNA replication in the rapidly dividing embryonic cells and to maintain genomic integrity in the mature organism. An enzyme involved in repair of replication errors generated on either normal or oxidatively damaged DNA templates, is the mammalian ortholog of the Escherichia coli MutY DNA glycosylase (MYH). We show that levels of MYH isoform, detected at the E14 embryonic stage, decrease during embryonic and neonatal rat development, while new isoforms appear and gradually increase in the neonate and adult brain. The temporally declining expression of embryonic MYH resembles the pattern of proliferating cell nuclear antigen (PCNA) decline during this period. Immunohistochemical analyses of the embryonic brain show that cells staining for MYH initially coincide with cells staining for PCNA. At later stages PCNA declines, while MYH is detected primarily outside the nucleus. MutY‐like glycosylase activity for adenines misincorporated opposite oxidized guanines is detected in both, embryonic and adult brain extracts. Together, these findings suggest that in proliferating embryonic cells, MYH might be primarily involved in post replicative repair of nuclear DNA, whereas in post mitotic neurons, in the repair of mitochondrial DNA.