bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction between flavonoids and the blood–brain barrier:in vitrostudies
Authors: Youdim Kuresh A. , Dobbie Michael S. , Kuhnle Gunter , Proteggente Anna R. , Abbott N. Joan , Rice‐Evans Catherine 
Published: July 2010

AbstractThere is considerable current interest in the neuroprotective effects of flavonoids. This study focuses on the potential for dietary flavonoids, and their known physiologically relevant metabolites, to enter the brain endothelium and cross the blood–brain barrier (BBB) using well‐establishedin vitromodels (brain endothelial cell lines and ECV304 monolayers co‐cultured with C6 glioma cells). We report that the citrus flavonoids, hesperetin, naringenin and their relevantin vivometabolites, as well as the dietary anthocyanins andin vivoforms, cyanidin‐3‐rutinoside and pelargonidin‐3‐glucoside, are taken up by two brain endothelial cell lines from mouse (b.END5) and rat (RBE4). In both cell types, uptake of hesperetin and naringenin was greatest, increasing significantly with time and as a function of concentration. In support of these observations we report for the first time high apparent permeability (Papp) of the citrus flavonoids, hesperetin and naringenin, across thein vitroBBB model (apical to basolateral) relative to their more polar glucuronidated conjugates, as well as those of epicatechin and itsin vivometabolites, the dietary anthocyanins and to specific phenolic acids derived from colonic biotransformation of flavonoids. The results demonstrate that flavonoids and some metabolites are able to traverse the BBB, and that the potential for permeation is consistent with compound lipophilicity.
Peripherin‐mediated death of motor neurons rescued by overexpression of neurofilament NF‐H proteins
Authors: Beaulieu Jean‐Martin , Julien Jean‐Pierre 
Published: July 2010

AbstractIn previous studies, we showed that overexpression of peripherin, a neuronal intermediate filament (IF) protein, in mice deficient for neurofilament light (NF‐L) subunits induced a progressive adult‐onset degeneration of spinal motor neurons characterized by the presence of IF inclusion bodies reminiscent of axonal spheroids found in amyotrophic lateral sclerosis (ALS). In contrast, the overexpression of human neurofilament heavy (NF‐H) proteins provoked the formation of massive perikaryal IF protein accumulations with no loss of motor neurons. To further investigate the toxic properties of IF protein inclusions, we generated NF‐L null mice thatco‐express both peripherin and NF‐H transgenes. The axonal count in L5 ventral roots from 6 and 8‐month‐old transgenic mice showed that NF‐H overexpression rescued the peripherin‐mediated degeneration of motor neurons. Our analysis suggests that the protective effect of extra NF‐H proteins is related to the sequestration of peripherin into the perikaryon of motor neurons, thereby abolishing the development of axonal IF inclusions that might block transport. These findings illustrate the importance of IF protein stoichiometry in formation, localization and toxicity of neuronal inclusion bodies.
Regulation by cycloheximide and lowered temperature of cell‐surface α7‐nicotinic acetylcholine receptor expression on transfected SH‐EP1 cells
Authors: Schroeder Katherine M. , Wu Jie , Zhao Lingke , Lukas Ronald J. 
Published: July 2010

AbstractHeterologous expression of functional, nicotinic acetylcholine receptors (nAChR) in mammalian cells has been difficult to achieve or optimize, even for nAChR containing only one kind of subunit. In this study, we determined effects of lowered temperature or of exposure to the protein synthesis inhibitor cycloheximide (CHX) on cell surface expression of homomeric α7‐nAChR in transfected SH‐EP1 human epithelial cells. We found that incubation of cells for 2 days at 25°C or in the presence of 0.5–2 μg/mL of CHX caused ∼four‐ or ∼eight‐fold increases, respectively, in surface binding sites for125I‐labeled α‐bungarotoxin (I‐Bgt). These increases were accompanied by increases in peak whole‐cell current responses to nicotinic agonists. Either treatment lowered protein synthesis and cell proliferation, but experiments using puromycin indicated that a reduction in protein synthesis or cell proliferation per se was not sufficient to increase surface binding. I‐Bgt binding to whole‐cell membrane pools increased in response to either treatment, suggesting that the increase in surface binding was due, at least in part, to an increase in intracellular receptor levels. The cyclophilin inhibitor cyclosporin A reduced surface expression in untreated as well as CHX‐ or 25°C‐treated cells. The results suggest practical means for increasing cell surface and functional expression of α7‐nAChR. Although these effects are not simply due to protein synthesis inhibition or reduced cell proliferation, they do involve an increase in intracellular receptor pool size.
Glutamate regulation of non‐quantal release of acetylcholine in the rat neuromuscular junction
Authors: Malomouzh Artem I. , Mukhtarov Marat R. , Nikolsky Eugen E. , Vyskočil František , Lieberman Edward M. , Urazaev Albert K. 
Published: July 2010

AbstractGlutamate, previously demonstrated to participate in regulation of the resting membrane potential in skeletal muscles, also regulates non‐quantal acetylcholine (ACh) secretion from rat motor nerve endings. Non‐quantal ACh secretion was estimated by the amplitude of endplate hyperpolarization (H‐effect) following blockade of skeletal muscle post‐synaptic nicotinic receptors by (+)‐tubocurarine and cholinesterase by armin (diethoxy‐p‐nitrophenyl phosphate). Glutamate was shown to inhibit non‐quantal release but not spontaneous and evoked quantal secretion of ACh. Glutamate‐induced decrease of the H‐effect was enhanced by glycine. Glycine alone also lowered the H‐effect, probably due to potentiation of the effect of endogenous glutamate present in the synaptic cleft. Inhibition ofN‐methyl‐d‐aspartate (NMDA) receptors with (+)‐5‐methyl‐10,11‐dihydro‐5H‐dibenzocyclohepten‐5,10‐imine (MK801),dl‐2‐amino‐5‐phosphopentanoic acid (AP5) and 7‐chlorokynurenic acid or the elimination of Ca2+from the bathing solution prevented the glutamate‐induced decrease of the H‐effect with or without glycine. Inhibition of muscle nitric oxide synthase byNG‐nitro‐l‐arginine methyl ester (l‐NAME), soluble guanylyl cyclase by 1H[1,2,4]oxadiazolo[4,3‐a]quinoxalin‐1‐one (ODQ) and binding and inactivation of extracellular nitric oxide (NO) by haemoglobin removed the action of glutamate and glycine on the H‐effect. The results suggest that glutamate, acting on post‐synaptic NMDA receptors to induce sarcoplasmic synthesis and release of NO, selectively inhibits non‐quantal secretion of ACh from motor nerve terminals. Non‐quantal ACh is known to modulate the resting membrane potential of muscle membrane via control of activity of chloride transport and a decrease in secretion of non‐quantal transmitter following muscle denervation triggers the early post‐denervation depolarization of muscle fibres.
ASK1–p38 MAPK/JNK signaling cascade mediates anandamide‐induced PC12 cell death
Authors: Sarker Krishna Pada , Biswas Kamal Krishna , Yamakuchi Munekazu , Lee Ki‐Young , Hahiguchi Teruto , Kracht Michael , Kitajima Isao , Maruyama Ikuro 
Published: July 2010

AbstractAnandamide is a neuroimmunoregulatory molecule that triggers apoptosis in a number of cell types including PC12 cells. Here, we investigated the molecular mechanisms underlying anandamide‐induced cell death in PC12 cells. Anandamide treatment resulted in the activation of p38 mitogen‐activated protein kinase (MAPK), c‐Jun N‐terminal kinase (JNK), and p44/42 MAPK in apoptosing cells. A selective p38 MAPK inhibitor, SB203580, or dn‐JNK, JNK1(A‐F) or SAPKβ(K‐R), blocked anandamide‐induced cell death, whereas a specific inhibitor of MEK‐1/2, U0126, had no effect, indicating that activation of p38 MAPK and JNK is critical in anandamide‐induced cell death. An important role for apoptosis signal‐regulating kinase 1 (ASK1) in this event was also demonstrated by the inhibition of p38 MAPK/JNK activation and death in cells overexpressing dn‐ASK1, ASK1 (K709M). Conversely, the constitutively active ASK1, ASK1ΔN, caused prolonged p38 MAPK/JNK activation and increased cell death. These indicate that ASK1 mediates anandamide‐induced cell death via p38 MAPK and JNK activation. Here, we also found that activation of p38 MAPK/JNK is accompanied by cytochromecrelease from the mitochondria and caspase activation (which can be inhibited by SB203580), suggesting that anandamide triggers a mitochondrial dependent apoptotic pathway. The caspase inhibitor, zVAD, and the mitochondrial pore opening inhibitor, cyclosporine A, blocked anandamide‐induced cell death but not p38 MAPK/JNK activation, suggesting that activation of these kinases may occur upstream of mitochondrial associated events.
Contribution of two conserved glycine residues to fibrillogenesis of the 106–126 prion protein fragment. Evidence that a soluble variant of the 106–126 peptide is neurotoxic
Authors: Florio Tullio , Paludi Domenico , Villa Valentina , Principe Daniela Rossi , Corsaro Alessandro , Millo Enrico , Damonte Gianluca , D'Arrigo Cristina , Russo Claudio , Schettini Gennaro , Aceto Antonio 
Published: July 2010

AbstractThe fibrillogenic peptide corresponding to the residues 106–126 of the prion protein sequence (PrP 106–126) is largely used to explore the neurotoxic mechanisms underlying the prion disease. However, whether the neuronal toxicity of PrP 106–126 is caused by a soluble or fibrillar form of this peptide is still unknown. The aim of this study was to correlate the structural state of this peptide with its neurotoxicity. Here we show that the two conserved Gly114 and Gly119 residues, in force of their intrinsic flexibility, prevent the peptide assuming a structured conformation, favouring its aggregation in amyloid fibrils. The substitution of both Gly114 and Gly119 with alanine residues (PrP 106–126 AA mutated peptide) reduces the flexibility of this prion fragment and results in a soluble, β‐structured peptide. Moreover, PrP 106–126 AA fragment was highly toxic when incubated with neuroblastoma cells, likely behaving as a neurotoxic protofibrillar intermediate of the wild‐type PrP 106–126. These data further confirm that the fibrillar aggregation is not necessary for the induction of the toxic effects of PrP 106–126.
High‐frequency stimulation of the subthalamic nucleus enhances striatal dopamine release and metabolism in rats
Authors: Meissner Wassilios , Harnack Daniel , Reese René , Paul Gesine , Reum Torsten , Ansorge Mark , Kusserow Heike , Winter Christine , Morgenstern Rudolf , Kupsch Andreas 
Published: July 2010

AbstractHigh‐frequency stimulation of the subthalamic nucleus is believed to exert its main effects via the basal ganglia output structures. Previously, we have shown a concomitant increase in striatal dopamine (DA) metabolites in normal and 6‐hydroxydopamine‐lesioned rats. The present study was designed to determine whether this increase in striatal DA metabolites reflects enhanced intraneuronal DA turnover or, alternatively, is due to increased DA release with subsequent rapid and efficient reuptake and/or metabolism. Thus, high‐frequency stimulation of the subthalamic nucleus was performed in normal rats after inhibition of DA reuptake, metabolism or DA depletion. Extracellular levels of striatal DA and its metabolites were assessed using microdialysis. Our data suggest that subthalamic high‐frequency stimulation increases striatal DA release and activates independent striatal DA metabolism. Since such changes could be triggered by modification of either the activity or the gene expression of the rate‐limiting enzyme tyrosine hydroxylase, an activity assay and RT‐PCR of striatal and nigral samples were performed. Subthalamic stimulation increased striatal tyrosine hydroxylase activity without affecting gene expression. We, therefore, conclude that the application of subthalamic high‐frequency stimulation could partially compensate for the DA deficit by inducing increased striatal DA release and metabolism.
Tetrahydrobiopterin precursor sepiapterin provides protection against neurotoxicity of 1‐methyl‐4‐phenylpyridinium in nigral slice cultures
Authors: Madsen Jakob Torp , Jansen Pernille , Hesslinger Christian , Meyer Morten , Zimmer Jens , Gramsbergen Jan Bert 
Published: July 2010

AbstractComplex‐I inhibition and oxidative processes have been implicated in the loss of nigral dopamine neurones in Parkinson's disease and the toxicity of MPTP and its metabolite MPP+. Tetrahydrobiopterin, an essential cofactor for tyrosine hydroxylase, may act as an antioxidant in dopaminergic neurones and protects against the toxic consequences of glutathione depletion. Here we studied the effects of manipulating tetrahydrobiopterin levels on MPP+toxicity in organotypic, rat ventral mesencephalic slice cultures. In cultures exposed to 30 µmMPP+for 2 days, followed by 8 days ‘recovery’ in control medium, we measured dopamine and its metabolites in the tissue and culture medium by HPLC, lactate dehydrogenase release to the culture medium, cellular uptake of propidium iodide and counted the tyrosine hydroxylase‐immunoreactive neurones. Inhibition of tetrahydrobiopterin synthesis by 2,4‐diamino‐6‐hydroxypyrimidine had no significant synergistic effect on MPP+toxicity. In contrast, the tetrahydrobiopterin precursorl‐sepiapterin attenuated the MPP+‐induced dopamine depletion and loss of tyrosine hydroxylase‐positive cells in a dose‐dependent manner with 40 µm l‐sepiapterin providing maximal protection. Accordingly, increasing intracellular tetrahydrobiopterin levels may protect against oxidative stress by complex‐I inhibition.
δ‐Opioid receptors exhibit high efficiency when activating trimeric G proteins in membrane domains
Authors: Bourova Lenka , Kostrnova Alexandra , Hejnova Lucie , Moravcova Zuzana , Moon Hyo‐Eun , Novotny Jiri , Milligan Graeme , Svoboda Petr 
Published: July 2010

AbstractLow‐density membrane fragments (domains) were separated from the bulk of plasma membranes of human embryonic kidney (HEK)293 cells expressing a δ‐opioid (DOP) receptor‐Gi1α fusion protein by drastic homogenization and flotation on equilibrium sucrose density gradients. The functional activity of trimeric G proteins and capacity of the DOP receptor to stimulate both the fusion protein‐linked Gi1α and endogenous pertussis‐toxin sensitive G proteins was measured asd‐Ala2,d‐Leu5‐enkephalin stimulated high‐affinity GTPase or guanosine‐5′‐[γ‐35S]triphosphate ([35S]GTPγS) binding. The maximumd‐Ala2‐d‐Leu5 enkephalin (DADLE)‐stimulated GTPase was two times higher in low‐density membrane fragments than in bulk of plasma membranes; 58 and 27 pmol/mg/min, respectively. The same difference was obtained for [35S]GTPγS binding. Contrarily, the low‐density domains contained no more than half the DOP receptor binding sites (Bmax = 6.6 pmol/mg versus 13.6 pmol/mg). Thus, when corrected for expression levels of the receptor, low‐density domains exhibited four times higher agonist‐stimulated GTPase and [35S]GTPγS binding than the bulk plasma membranes. The regulator of G protein signaling RGS1, enhanced further the G protein functional activity but did not remove the difference between domain‐bound and plasma membrane pools of G protein. The potency of the agonist in functional studies and the affinity of specific [3H]DADLE binding to the receptor were, however, the same in both types of membranes – EC50 = 4.5 ± 0.1 × 10−8and 3.2 ± 1.4 × 10−8 mfor GTPase;Kd = 1.2 ± 0.1 and 1.3 ± 0.1 nmfor [3H]DADLE radioligand binding assay. Similar results were obtained when sodium bicarbonate was used for alkaline isolation of membrane domains. By contrast, detergent‐insensitive membrane domains isolated following treatment of cells with Triton X100 exhibited no DADLE‐stimulated GTPase or GTPγS binding. Functional coupling between the DOP receptor and cognate G proteins was also blocked by high‐energy ultrasound and repeated freezing‐thawing. Our data indicate, for the first time, that membrane domains isolated using ‘detergent‐free’ procedures exhibit higher efficiency of coupling between a G protein‐coupled receptor and its corresponding G protein(s) than bulk plasma membranes. Detergent‐extraction diminishes these interactions, even when the receptor and G proteins are physically tethered together.
Fluorescent two‐dimensional difference gel electrophoresis and mass spectrometry identify age‐related protein expression differences for the primary visual cortex of kitten and adult cat
Authors: Van den Bergh Gert , Clerens Stefan , Cnops Lieselotte , Vandesande Frans , Arckens Lutgarde 
Published: July 2010

AbstractThe recent introduction of fluorescent two‐dimensional difference gel electrophoresis, combined with mass spectrometry, has greatly simplified the analysis and identification of differentially expressed proteins by eliminating intergel variability. In this report, we describe the successful application of this functional proteomics approach to compare protein expression levels in visual cortical area 17 of adult cats and 30‐day‐old kittens, in order to identify proteins expressed in an age‐related fashion. We identified 16 proteins that were more abundantly expressed in kitten striate cortex and 12 proteins with a pronounced expression in adult cat area 17. Among those isolated from kitten area 17 were proteins related to axon growth and growth cone guidance and to the formation of cytoskeletal filaments. Glial fibrillary acidic protein, as identified in adult cat area 17, has been implicated previously in the termination of the critical period for cortical plasticity in kittens. In situ hybridization experiments for two of the identified proteins, glial fibrillary acidic protein and collapsin response mediator protein 5, confirmed and extended their differential expression to the mRNA level. Our findings show that two‐dimensional difference gel electrophoresis combined with mass spectrometry is a powerful approach that permits the identification of small protein expression differences correlated to different physiological conditions.
State‐dependent phosphorylation of ε‐isozyme of protein kinase C in adult rat dorsal root ganglia after inflammation and nerve injury
Authors: Zhou Yu , Li Guo‐Dong , Zhao Zhi‐Qi 
Published: July 2010

AbstractThe ε‐isozyme of protein kinase C (PKCε) and the vanilloid receptor 1 (VR1) are both expressed in dorsal root ganglion (DRG) neurons and are reported to be predominantly and specifically involved in nociceptive function. Using phosphospecific antibody against the C‐terminal hydrophobic site Ser729 of PKCε as a marker of enzyme activation, the state‐dependent activation of PKCε, as well as the expression of VR1 in rat DRG neurons, was evaluated in different experimental pain models in vivo. Quantitative analysis showed that phosphorylation of PKCε in DRG neurons was significantly up‐regulated after carrageen‐ and Complete Freund's Adjuvant‐induced inflammation, while it was markedly down‐regulated after chronic constriction injury. A double‐labeling study showed that phosphorylation of PKCε was expressed predominantly in VR1 immunoreactivity positive small diameter DRG neurons mediating the nociceptive information from peripheral tissue to spinal cord. The VR1 protein expression showed no significant changes after either inflammation or chronic constriction injury. These data indicate that functional activation of PKCε has a close relationship with the production of inflammatory hyperalgesia and the sensitization of the nociceptors. Inflammatory mediator‐induced activation of PKCε and subsequent sensitization of VR1 to noxious stimuli by PKCε may be involved in nociceptor sensitization.
Zinc inhibition of cellular energy production: implications for mitochondria and neurodegeneration
Authors: Dineley Kirk E. , Votyakova Tatyana V. , Reynolds Ian J. 
Published: July 2010

AbstractAn increasing body of evidence suggests that high intracellular free zinc promotes neuronal death by inhibiting cellular energy production. A number of targets have been postulated, including complexes of the mitochondrial electron transport chain, components of the tricarboxylic acid cycle, and enzymes of glycolysis. Consequences of cellular zinc overload may include increased cellular reactive oxygen species (ROS) production, loss of mitochondrial membrane potential, and reduced cellular ATP levels. Additionally, zinc toxicity might involve zinc uptake by mitochondria and zinc induction of mitochondrial permeability transition. The present review discusses these processes with special emphasis on their potential involvement in brain injury.
Xenobiotic response element binding enriched in both nuclear and microsomal fractions of rat cerebellum
Authors: Kuramoto Nobuyuki , Baba Katsuhiro , Gion Keiko , Sugiyama Chie , Taniura Hideo , Yoneda Yukio 
Published: July 2010

AbstractXenobiotic response element (XRE) is a core nucleotide sequence at the upstream of inducible target genes for the transcription factor aryl hydrocarbon receptor (AhR) that is responsible for signal transduction of exogenous environmental pollutants in eukaryotic cells. Immunoblotting analysis revealed the constitutive expression of AhR‐related proteins in rat liver and brain, while specific binding of a radiolabelled probe containing XRE was detected in nuclear preparations of both liver and brain on gel retardation electrophoresis. Among discrete rat brain structures examined, cerebellum exhibited the highest XRE binding with less potent binding in hypothalamus, midbrain, medulla‐oblongata, hippocampus, cerebral cortex and striatum. In contrast to liver and hippocampus, cerebellum also contained unusually higher XRE binding in microsomal fractions than that in either nuclear or mitochondrial fractions. Limited proteolysis by V8 protease did not markedly affect XRE binding in cerebellar nuclear extracts, with concomitant diminution of that in hepatic and hippocampal nuclear extracts. In primary cultured cerebellar neurons, indigo was effective in significantly increasing XRE binding only when determined immediately after sustained exposure for 120 min in the presence of high potassium chloride. These results suggest the abundance of as‐yet unidentified proteins with high affinity for XRE and responsiveness to indigo in both nuclear and microsomal fractions of rat cerebellum.
Social isolation‐induced increase in the sensitivity of rats to the steroidogenic effect of ethanol
Authors: Serra Mariangela , Pisu M. Giuseppina , Floris Ivan , Cara Valeria , Purdy Robert H. , Biggio Giovanni 
Published: July 2010

AbstractSocial isolation of rats for 30 days immediately after weaning results in marked decreases in the cerebrocortical and plasma concentrations of pregnenolone, progesterone, 3α‐hydroxy‐5α‐pregnan‐20‐one (3α,5α‐TH PROG), and 3α,5α‐tetrahydrodeoxycorticosterone (3α,5α‐TH DOC), as well as a moderate increase in the plasma concentration of corticosterone. This mildly stressful condition has now been shown to increase the sensitivity of rats to the effect of acute ethanol administration on the cerebrocortical and plasma concentrations of neuroactive steroids. The percentage increases in the brain and plasma concentrations of pregnenolone, progesterone, 3α,5α‐TH PROG, and 3α,5α‐TH DOC, apparent 20 min after a single intraperitoneal injection of ethanol (1 g/kg), were thus markedly greater in isolated rats than in group‐housed animals. A subcutaneous injection of isoniazid (300 mg/kg) also induced greater percentage increases in the concentrations of these steroids in isolated rats than in group‐housed animals. These results suggest that mild chronic stress, such as that induced by social isolation, enhances the steroidogenic effect of ethanol, a drug abused by humans under stress or affected by neuropsychiatric disorders. Social isolation also induced hyper‐responsiveness of the hypothalamic–pituitary–adrenal (HPA) axis, as was apparent after reduction of GABA‐mediated inhibitory tone by isoniazid administration.