bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parkinson's disease transgenic mitochondrial cybrids generate Lewy inclusion bodies
Authors: Trimmer Patricia A. , Borland M. Kathleen , Keeney Paula M. , Bennett James P. , Parker W. Davis 
Published: July 2010

AbstractMany models of Parkinson's disease (PD) have succeeded in replicating dopaminergic neuron loss or α‐synuclein aggregation but not the formation of classical Lewy bodies, the pathological hallmark of PD. Our cybrid model of sporadic PD was created by introducing the mitochondrial genes from PD patients into neuroblastoma cells that lack mitochondrial DNA. Previous studies using cybrids have shown that information encoded by mitochondrial DNA in patients contributes to many pathogenic features of sporadic PD. In this paper, we report the generation of fibrillar and vesicular inclusions in a long‐term cybrid cell culture model that replicates the essential antigenic and structural features of Lewy bodies in PD brain without the need for exogenous protein expression or inhibition of mitochondrial or proteasomal function. The inclusions generated by PD cybrid cells stained with eosin, thioflavin S, and antibodies to α‐synuclein, ubiquitin, parkin, synphilin‐1, neurofilament, β‐tubulin, the proteasome, nitrotyrosine, and cytochrome c. Future studies of these cybrids will enable us to better understand how Lewy bodies form and what role they play in the pathogenesis of PD.
An ALS mouse model with a permeable blood–brain barrier benefits from systemic cyclosporine A treatment
Authors: Kirkinezos Ilias G. , Hernandez Dayami , Bradley Walter G. , Moraes Carlos T. 
Published: July 2010

AbstractTo test potentially beneficial drugs to amyotrophic lateral sclerosis (ALS), we created an ALS mouse model with a permeable blood–brain barrier, by crossing the G93A‐SOD1 transgenic mouse with a multiple drug resistance type 1a/b (mdr1a/b) gene knockout mouse. To validate the model, we administered cyclosporine A intraperitoneally to the mice. Cyclosporine A accumulated in the brain and spinal cord of this mouse model, whereas it was unable to penetrate the CNS of mdr1a/b wild‐type animals. Systemic administration of cyclosporine A extended the life of the double‐mutant male mice by approximately 12%. Surprisingly, the effect was more robust in male mice and only marginal in female mice. These results demonstrate the usefulness of this combined mouse model for the testing of potentially therapeutic drugs and support the role of mitochondrial‐mediated apoptosis in the pathway to motor neuron death in SOD1‐associated ALS.
Neuron‐glia communication: metallothionein expression is specifically up‐regulated by astrocytes in response to neuronal injury
Authors: Chung Roger S. , Adlard Paul A. , Dittmann Justin , Vickers James C. , Chuah Meng Inn , West Adrian K. 
Published: July 2010

AbstractRecent data suggests that metallothioneins (MTs) are major neuroprotective proteins within the CNS. In this regard, we have recently demonstrated that MT‐IIA (the major human MT‐I/‐II isoform) promotes neural recovery following focal cortical brain injury. To further investigate the role of MTs in cortical brain injury, MT‐I/‐II expression was examined in several different experimental models of cortical neuron injury. While MT‐I/‐II immunoreactivity was not detectable in the uninjured rat neocortex, by 4 days, following a focal cortical brain injury, MT‐I/‐II was found in astrocytes aligned along the injury site. At latter time points, astrocytes, at a distance up to several hundred microns from the original injury tract, were MT‐I/‐II immunoreactive. Induced MT‐I/‐II was found both within the cell body and processes. Using a cortical neuron/astrocyte co‐culture model, we observed a similar MT‐I/‐II response following in vitro injury. Intriguingly, scratch wound injury in pure astrocyte cultures resulted in no change in MT‐I/‐II expression. This suggests that MT induction was specifically elicited by neuronal injury. Based upon recent reports indicating that MT‐I/‐II are major neuroprotective proteins within the brain, our results provide further evidence that MT‐I/‐II plays an important role in the cellular response to neuronal injury.
Brain capillary endothelium and choroid plexus epithelium regulate transport of transferrin‐bound and free iron into the rat brain
Authors: Deane Rashid , Zheng Wei , Zlokovic Berislav V. 
Published: July 2010

AbstractIron transport into the CNS is still not completely understood. Using a brain perfusion technique in rats, we have shown a significant brain capillary uptake of circulating transferrin (Tf)‐bound and free 59Fe (1 nm) at rates of 136 ± 26 and 182 ± 23 μL/g/min, respectively, while their respective transport rates into brain parenchyma were 1.68 ± 0.56 and 1.52 ± 0.48 μL/g/min. Regional Tf receptor density (Bmax) in brain endothelium determined with 125I‐holo‐Tf correlated well with 59Fe‐Tf regional brain uptake rates reflecting significant vascular association of iron. Tf‐bound and free circulating 59Fe were sequestered by the choroid plexus and transported into the CSF at low rates of 0.17 ± 0.01 and 0.09 ± 0.02 μL/min/g, respectively, consistent with a 10‐fold brain‐CSF concentration gradient for 59Fe, Tf‐bound or free. We conclude that transport of circulating Tf‐bound and free iron could be equally important for its delivery to the CNS. Moreover, data suggest that entry of Tf‐bound and free iron into the CNS is determined by (i) its initial sequestration by brain capillaries and choroid plexus, and (ii) subsequent controlled and slow release from vascular structures into brain interstitial fluid and CSF.
Acetylcholine turnover rates in rat brain regions during cocaine self‐administration
Authors: Smith James E. , Vaughn Tina C. , Co Conchita 
Published: July 2010

AbstractThe involvement of cholinergic neurons in the brain processes underlying reinforcement has been recently demonstrated. This experiment assessed the potential role of cholinergic neurons in cocaine reinforcement by measuring the turnover rates of acetylcholine in brain regions of rats self‐administering cocaine and in yoked cocaine and yoked vehicle‐infused controls. The activity of cholinergic innervations of and/or interneurons in the olfactory tubercle, caudate putamen, diagonal band‐pre‐optic region, ventral pallidum, lateral and medial hypothalamus, hippocampus, ventral tegmental area and visual cortices reflected by the turnover rates of acetylcholine were significantly altered in rats self‐administering cocaine compared to yoked cocaine infused controls. These changes implicate the involvement of cholinergic neurons with cell bodies in the diagonal band‐pre‐optic region, the medial septum and several brainstem nuclei and interneurons in the caudate‐putamen and ventral pallidum in the processes underlying cocaine self‐administration. The identified cholinergic neuronal systems may have a broader role in the brain processes for natural reinforcers (i.e. food, water, etc.) since drugs of abuse are believed to produce reinforcing effects through these systems.
Noradrenaline transporter blockers raise extracellular dopamine in medial prefrontal but not parietal and occipital cortex: differences with mianserin and clozapine
Authors: Valentini V. , Frau R. , Di Chiara G. 
Published: July 2010

AbstractThis study compared the interaction between noradrenaline (NA) and dopamine (DA) mechanisms in the prefrontal (PFCX) and in the parietal (ParCX) and occipital (OccCX) cortex. The effect of reboxetine and desipramine, two NA transporter blockers, of mianserin, an antagonist of α2and 5‐HT2 receptors, and of clozapine, an atypical antipsychotic, on dialysate DA in the medial PFCX, ParCX and OccCX was studied. We also assessed the influence of a prior 6‐hydroxydopamine (6‐OHDA) lesion of the dorsal noradrenergic bundle (DNAB) on the effect of reboxetine and clozapine on dialysate DA in the PFCX and ParCX. Systemic administration of reboxetine and desipramine dose‐dependently increased dialysate DA in the PFCX but not in the ParCX and OccCX. In contrast, mianserin and clozapine raised dialysate DA in the ParCX and OccCX to an even larger extent than in the PFCX. 6‐OHDA lesions of DNAB abolished the increase of dialysate DA elicited by reboxetine in the PFCX and by clozapine both in the PFCX and in the ParCX. It is concluded that, although PFCX and ParCX/OccCX share the presence of a strong control of DA transmission by NA through α2receptors, they differ in the extent to which DA is cleared from the extracellular compartment by uptake through the NA transporter. This process, although extensive in the PFCX, appears insignificant in the ParCX and OccCX, probably as a result of the higher ratio of NA to DA resulting in exclusion of DA from NA transporter.
Alpha2‐adrenoceptor mediated co‐release of dopamine and noradrenaline from noradrenergic neurons in the cerebral cortex
Authors: Devoto Paola , Flore Giovanna , Pira Luigi , Longu Giorgio , Gessa Gian Luigi 
Published: July 2010

AbstractPrevious results suggest that extracellular dopamine (DA) in the rat cerebral cortex originates from dopaminergic and noradrenergic terminals. To further clarify this issue, dialysate DA, dihydroxyphenylacetic acid (DOPAC) and noradrenaline (NA) were measured both in the medial prefrontal cortex (mPFC) and in the occipital cortex (OCC), with dense and scarce dopaminergic projections, respectively. Moreover, the effect of the α2‐adrenoceptor antagonist RS 79948 and the D2‐receptor antagonist haloperidol on extracellular DA, DOPAC and NA was investigated. Extracellular DA and DOPAC concentrations in the OCC were 43% and 9%, respectively, those in the mPFC. Haloperidol (0.1 mg/kg i.p.) increased DA and DOPAC (by 35% and 150%, respectively) in the mPFC, but was ineffective in the OCC. In contrast, RS 79948 (1.5 mg/kg i.p.) increased NA, DA and DOPAC, both in the mPFC (by approximately 50%, 60% and 130%, respectively) and the OCC (by approximately 50%, 80% and 200%, respectively). Locally perfused, the DA transporter blocker GBR 12909 (10 µm) was ineffective in either cortex, whereas desipramine (DMI, 100 µm) markedly increased extracellular NA and DA in both cortices. The weak haloperidol effect on DA efflux was not enhanced after DA‐ and NA‐transporter blockade, whereas after DMI, RS 79948 markedly increased extracellular NA, and especially DA and DOPAC in both cortices. The results support the hypothesis that most extracellular DA in the cortex is co‐released with NA from noradrenergic terminals, such co‐release being primarily controlled by α2‐adrenoceptors.
In vivo efflux of serotonin in the dorsal raphe nucleus of 5‐HT1Areceptor knockout mice
Authors: Bortolozzi Analía , Amargós‐Bosch Mercè , Toth Miklos , Artigas Francesc , Adell Albert 
Published: July 2010

AbstractIn the dorsal raphe nucleus (DR), extracellular serotonin (5‐HT) regulates serotonergic transmission through 5‐HT1Aautoreceptors. In this work we usedin vivomicrodialysis to examine the effects of stressful and pharmacological challenges on DR 5‐HT efflux in 5‐HT1Areceptor knockout (5‐HT1A–/–) mice and their wild‐type counterparts (5‐HT1A+/+). Baseline 5‐HT concentrations did not differ between both lines of mice, which is consistent with a lack of tonic control of 5‐HT1Aautoreceptors on DR 5‐HT release. (R)‐(+)‐8‐Hydroxy‐2‐(di‐n‐propylamino)tetralin hydrobromide (8‐OH‐DPAT, 0.5 mg/kg) reduced 5‐HT levels to 30% of basal values in 5‐HT1A+/+ mice, but not in 5‐HT1A–/– mice. The selective 5‐HT1Breceptor agonist 1,4‐dihydro‐3‐(1,2,3,6‐tetrahydro‐4‐pyridinyl)‐5H‐pyrrolo[3,2‐b]pyridin‐5‐one dihydrochloride (CP 93129, 300 µm) reduced dialysate 5‐HT to the same extent (30–40% of baseline) in the two genotypes, which suggests a lack of compensatory changes in 5‐HT1Breceptors in the DR of such mutant mice. Both a saline injection and handling for 3 min increased DR dialysate 5‐HT in mutants, but not in 5‐HT1A+/+ mice. Fluoxetine (5 and 20 mg/kg) elevated 5‐HT in a dose‐dependent manner in both genotypes. However, this effect was markedly more pronounced in the 5‐HT1A–/– mice. The increased responsiveness of the extracellular 5‐HT in the DR of 5‐HT1Areceptor knockout mice reflects a lack of the autoinhibitory control exerted by 5‐HT1Aautoreceptors.
Dopamine neurons in culture express VGLUT2 explaining their capacity to release glutamate at synapses in addition to dopamine
Authors: Dal Bo Gregory , St‐Gelais Fannie , Danik Marc , Williams Sylvain , Cotton Mathieu , Trudeau Louis‐Eric 
Published: July 2010

AbstractDopamine neurons have been suggested to use glutamate as a cotransmitter. To identify the basis of such a phenotype, we have examined the expression of the three recently identified vesicular glutamate transporters (VGLUT1‐3) in postnatal rat dopamine neurons in culture. We found that the majority of isolated dopamine neurons express VGLUT2, but not VGLUT1 or 3. In comparison, serotonin neurons express only VGLUT3. Single‐cell RT‐PCR experiments confirmed the presence of VGLUT2 mRNA in dopamine neurons. Arguing for phenotypic heterogeneity among axon terminals, we find that only a proportion of terminals established by dopamine neurons are VGLUT2‐positive. Taken together, our results provide a basis for the ability of dopamine neurons to release glutamate as a cotransmitter. A detailed analysis of the conditions under which DA neurons gain or loose a glutamatergic phenotype may provide novel insight into pathophysiological processes that underlie diseases such as schizophrenia, Parkinson's disease and drug dependence.
Progressive sensorimotor impairment is not associated with reduced dopamine and high energy phosphate donors in a model of ataxia‐telangiectasia
Authors: Mount Howard T. J. , Martel Jean‐Claude , Fluit Paul , Wu Yingji , Gallo‐Hendrikx Eleanor , Cosi Cristina , Marien Marc R. 
Published: July 2010

AbstractAtaxia‐telangiectasia (A‐T) is a genetic disease, associated with progressive motor impairment and a lack of functional ATM protein. It has been reported that immunoreactive tyrosine hydroxylase and dopamine transporter are reduced in anAtm–/–mouse model of A‐T. These observations led to a hypothesis that A‐T is associated with loss of nigrostriatal dopamine and prompted the launch of clinical trials to evaluate a therapeutic utility of the anti‐parkinsonian drug,l‐DOPA. To test for dopamine depletion more directly, we measured regional levels of monoamines and their metabolites in theAtm–/–mouse brain. We also measured levels of NAD+, a cofactor for dopamine biosynthesis and substrate of the DNA damage surveillance enzyme, poly(ADP‐ribose) polymerase (PARP). Constitutive activation of PARP has been posited to cause NAD+depletion. We observed no reduction in monoamine transmitters and no depletion of NAD+, or other high energy phosphate donors in the adultAtm–/–cerebellum, striatum, or ventral mesencephalon. However, our studies did reveal a progressive sensorimotor impairment inAtm–/–mice that may serve as a relevant proxy for progressive neurological impairment in the human disease. Our results call into question the involvement of dopamine in A‐T and the therapeutic strategy of enhancing dopaminergic function withl‐DOPA.
Presenilin‐1 and intracellular calcium stores regulate neuronal glutamate uptake
Authors: Yang Yaxiong , Kinney Gregory A. , Spain William J. , Breitner John C. S. , Cook David G. 
Published: July 2010

AbstractGlutamate uptake by high affinity glutamate transporters is essential for preventing excitotoxicity and maintaining normal synaptic function. We have discovered a novel role for presenilin‐1 (PS1) as a regulator of glutamate transport. PS1‐deficient neurons showed a decrease in glutamate uptake of approximately 50% compared to wild‐type neurons. Gamma‐secretase inhibitor treatment mimicked the effects of PS1 deficiency on glutamate uptake. PS1 loss‐of‐function, accomplished by PS1 deficiency or γ‐secretase inhibitor treatment, caused a corresponding decrease in cell surface expression of the neuronal glutamate transporter, EAAC1. PS1 deficiency is known to reduce intracellular calcium stores. To explore the possibility that PS1 influences glutamate uptake via regulation of intracellular calcium stores, we examined the effects of treating neurons with caffeine, thapsigargin, and SKF‐96365. These compounds depleted intracellular calcium stores by distinct means. Nonetheless, each treatment mimicked PS1 loss‐of‐function by impairing glutamate uptake and reducing EAAC1 expression at the cell surface. Blockade of voltage‐gated calcium channels, activation and inhibition of protein kinase C (PKC), and protein kinase A (PKA) all had no effect on glutamate uptake in neurons. Taken together, these findings indicate that PS1 and intracellular calcium stores may play a significant role in regulating glutamate uptake and therefore may be important in limiting glutamate toxicity in the brain.
Pseudophosphorylation of tau protein alters its ability for self‐aggregation
Authors: Haase C. , Stieler J. T. , Arendt T. , Holzer M. 
Published: July 2010

AbstractFilamentous tau protein deposits are a pathological hallmark of a group of neurodegenerative disorders (tauopathies). Tau protein in these aggregates is highly phosphorylated at different phosphorylation sites. Although tau filaments can be formed by heparin‐induced aggregation of unphosphorylated recombinant tau, it is not known how tau phosphorylation modulates aggregation behaviour. Analysis of the effect of tau phosphorylation at defined single or multiple sites is hampered by the low specificity of protein kinases and the highly dynamic turnover of phosphorylation in vivo. To overcome this problem we employed site‐directed mutagenesis to convert serine and threonine to aspartic acid or glutamic acid, which introduce a negative charge and conformational change that mimic phosphorylation. We tested 14 different mutated tau proteins for their propensity for self‐aggregation and formation of tau filaments. Tau aggregation was monitored with thioflavin S fluorescence in the presence of different inducers such as heparin, Al3+, Fe2+ and Fe3+. We found that mutations in the N‐terminal portion up to amino acid 208 mainly suppress tau aggregation, whereas mutations in the C‐terminal region mainly lead to an enhanced aggregation. Mutations in the middle portion of tau showed a mixed picture of suppression and enhancement of aggregation. A single amino acid change Ser422Glu has aggregation‐favouring properties with all four inducers.
M1 and M4 muscarinic receptors from hippocampus are positively involved in memory consolidation
Authors: Jerusalinsky D. , Kornisiuk E. , Romanelli Ferreira A. , Sánchez G. , Fürstenau L. , Blanco C. , Cerveñansky C. , Quillfeldt J. 
Published: July 2010

The muscarinic antagonist scopolamine causes amnesia in rats, both systemically or administered into the hippocampus after training, supporting the involvement of muscarinic receptors (MAChR) in memory. The role of MAChR subtypes was poorly understood in vivo due to the lack of enough selective pharmacological tools. Central M1, M3 and M5 receptors are mainly coupled to the phosphoinositide pathway, while central M2 and M4 receptors couple to the inhibition of stimulated adenylate cyclase (AC).Muscarinic toxins (MTs) from Dendroaspis snakes venom are selective for MAChR subtypes. MT1 and MT2, with affinity order M1M4 other subtypes, behaved as M1 agonists in various preparations. MT3 is highly selective for M4 receptors. These MTs fully antagonised the muscarinic inhibition of FSK‐stimulated hippocampal AC. As these MTs have negligible binding to M2 receptor, the M4 subtype must be responsible for most of the AC inhibition. Pirenzepine, an antagonist with similar affinity for M1 and M4, given into the hippocampus after an inhibitory avoidance task was amnesic. MT1 and MT2 facilitated memory consolidation, corroborating the positive involvement of M1 receptors. At a higher dose of MT2, the facilitation disappeared, suggesting that it was acting at another site, likely blocking M4 receptors. These results strongly support that M4 receptor of the hippocampus, responsible for muscarinic inhibition of AC, positively modulates memory consolidation.
Metabolic influence of gabapentin in brain
Authors: LaNoue K. F. , Kreiger J. , Xu Y. , Wood M. , Berkich D. A. , Hutson S. M. 
Published: July 2010

De novo synthesis of glutamate in excised rat retinas results in incorporation of 14CO2 into neuronal glutamate that is partially (30%) inhibited by the neuroactive drug gabapentin (Lieth et al. 2001). Gabapentin inhibits the cytosolic form of branched chain aminotransferase (BCATc) and prevents formation of glutamate via transamination of α‐ketoglutarate by branched chain aminoacids. The present study was an evaluation of the influence of gabapentin on glutamate synthesis in the whole brain in vivo. Gabapentin or vehicle was given IP (100 mg/kg) 30 min prior to the experiment. The rats were continuously infused through the jugular vein with H14CO3 (1.0 mCi/h) and U13C‐glucose (1 mm) while blood samples were taken from the carotid artery. Blood H14CO3 specific activity and U13C glucose concentration remained constant throughout infusions and rats were sacrificed at 5, 10, 20, 40 and 60 min Heads were quick frozen in liquid nitrogen and frozen brains removed and extracted with perchloric acid. 14C‐metabolites were separated chromatographically and assayed as described previously. The 13C data are currently being analyzed to determine 13C‐glutamate turnover. The 14C‐glutamate specific activity increased with a half‐life of 6 ± 1 min in control rats and 9 ± min in gabapentin treated rats. At steady state, the H14CO3 in the control glutamate pool was 8.90 ± 0.3 and 7.92 ± 0.6 nmoles/mg protein in the gabapentin pool. The corresponding values in the glutamine pools were 9.48 ± 0.4 and 7.73 ± 0.6 nmoles/mg protein. The data suggest that gabapentin also inhibits de novo synthesis of glutamate in the whole brain but less so than in the intact excised retina. Nevertheless, gabapentin may induce larger changes in brain areas with high concentrations of glutamatergic neurons.
Perforin and granzyme mediated toxicity on cultured oligodendrocytes
Authors: Knapp P. E. , Adams M. H. , Holder J. M. , Hudig D. 
Published: July 2010

Oligodendrocytes (OLs) are major targets of immune‐mediated demyelination in multiple sclerosis. Perforin, a pore‐forming protein released from cytolytic granules of cytotoxic T‐cells and NK cells, is implicated as an effector in inflammatory conditions leading to demyelination. Cytolytic granules contain other proteins which may also promote demyelination, including the serine dependent protease granzyme B. We used a repeated measures assay to test effects of enriched perforin, granzymes and total granule extracts on survival of individual OLs over 72 h. Granules were isolated from rat RNK‐16 cells. Granzymes and perforin were isolated by Cu + 2‐immobilized metal affinity chromatography. Lytic activity/mL at 4 h was calculated for all preparations. We assayed survival of both mature and immature OLs to determine developmental sensitivity. Cells were exposed to perforin, granzymes, perforin + granzymes, granule extract or control buffers for 1–3 h. Survival of mature OLs with large processes and membrane expansions was reduced by granule extracts but unaffected by perforin and granzymes. Immature OLs with a bipolar morphology or with multiple, thin processes were vulnerable to both perforin and granzymes alone and in combination, and to granule extracts. The majority of cell death in all cases occurred by 24 h. Results suggest that cytolytic granules contain factors that are toxic to OLs at all developmental stages and that immature OLs are differentially sensitive to perforin and/or granzyme mediated toxicity. Cytolytic granules may thus have a dual effect, to promote demyelination and to limit remyelination by targeting newly generated OLs.Acknowledgements: Supported by Natl. MS Soc. (PEK) & NIH R01 CA38942 (DH).