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Rat Cortical Neurons (rat + cortical_neuron)
Kinds of Rat Cortical Neurons Selected AbstractsA Nonfibrillar Form of the Fusogenic Prion Protein Fragment [118-135] Induces Apoptotic Cell Death in Rat Cortical NeuronsJOURNAL OF NEUROCHEMISTRY, Issue 6 2000Thierry Pillot Abstract: Neuronal loss is a salient feature of prion diseases.However, its cause and mechanism, particularly its relationship with theaccumulation and precipitation of the pathogenic, protease-resistant isoformPrPSc of the cellular prion protein PrPC, are still anenigma. Several studies suggest that neuronal loss could occur through aprocess of programmed cell death, which is consistent with the lack ofinflammation in these conditions. By analogy with the pathological eventsoccurring during the development of Alzheimer's disease, controversies stillexist regarding the relationship between amyloidogenesis, prion aggregation,and neuronal loss. We recently demonstrated that a prion protein fragment(118-135) displayed membrane-destabilizing properties and was able to induce,in a nonfibrillar form, the fusion of unilamellar liposomes. To unravel themechanism of prion protein neurotoxicity, we characterize the effects of thehuman Pr[118-135] peptide on rat cortical neurons. We demonstrate that lowconcentrations of the Pr[118-135] peptide, in a nonfibrillar form, induce atime- and dose- dependent apoptotic cell death, including caspase activation,DNA condensation, and fragmentation. This toxicity might involve oxidativestress, because antioxidant molecules, such as probucol and propyl gallate,protect neurons against prion peptide toxicity. By contrast, a nonfusogenicvariant Pr[118-135, 0°] peptide, which displays the same amino acidcomposition but several amino acid permutations, is not toxic to corticalneurons, which emphasizes the critical role of the fusogenic properties of theprion peptide in its neurotoxicity. Taken together, our results suggest thatthe interaction between the Pr[118-135] peptide and the plasma membrane ofneurons might represent an early event in a cascade leading toneurodegeneration. [source] Blockade by ferrous iron of Ca2+ influx through N -methyl- d -aspartate receptor channels in immature cultured rat cortical neuronsJOURNAL OF NEUROCHEMISTRY, Issue 1 2002Noritaka Nakamichi Abstract Rat cortical neurons cultured for 3 days in vitro were loaded with the fluorescent indicator fluo-3 for assessment of intracellular free calcium ion (Ca2+) concentrations with the aid of a confocal laser-scanning microscope. In the absence of added MgCl2, the addition of NMDA induced a rapid but sustained increase in the number of fluorescent neurons in a concentration-dependent manner at a concentration range of 1,100 µm with the increase by KCl being transient. The addition of FeCl2, but not FeCl3, markedly inhibited the increase by NMDA in a reversible manner at concentrations of 10,200 µm, without affecting that by KCl. Extensive analyses revealed clear differentiation between inhibitions by ferrous iron and other channel blockers known to date. The inhibition by FeCl2 was completely prevented by the addition of two different iron chelators. Exposure to NMDA alone did not lead to cell death in immature cultured neurons, however, while further addition of FeCl2 invariably induced neuronal cell death 24 h after exposure. These results give support to our previous proposal that NMDA receptor complex may contain a novel site sensitive to blockade by ferrous iron in rat brain. [source] Rearrangement of microtubule polarity orientation during conversion of dendrites to axons in cultured pyramidal neuronsCYTOSKELETON, Issue 5 2007Daisuke Takahashi Abstract Axons and dendrites of neurons differ in the polarity orientation of their microtubules. Whereas the polarity orientation of microtubules in axons is uniform, with all plus ends distal, that in dendrites is nonuniform. The mechanisms responsible for establishment and maintenance of microtubule polarity orientation in neuronal processes remain unclear, however. We previously described a culture system in which dendrites of rat cortical neurons convert to axons. In the present study, we examined changes in microtubule polarity orientation in such dendrites. With the use of the hooking procedure and electron microscopy, we found that microtubule polarity orientation changed from nonuniform to uniform, with a plus end-distal arrangement, in dendrites that gave rise to axons during culture of neurons for 24 h. Microtubule polarity orientation remained nonuniform in dendrites that did not elongate. Axon regeneration at the dendritic tip thus triggered the disappearance of minus end-distal microtubules from dendrites. These minus end-distal microtubules also disappeared from dendrites during axon regeneration in the presence of inhibitors of actin polymerization, suggesting that actin-dependent transport of microtubules is not required for this process and implicating a previously unidentified mechanism in the establishment and maintenance of microtubule polarity orientation in neuronal processes. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source] Involvement of astroglial ceramide in palmitic acid-induced Alzheimer-like changes in primary neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2007Sachin Patil Abstract A high-fat diet has been shown to significantly increase the risk of the development of Alzheimer's disease (AD), a neurodegenerative disease histochemically characterized by the accumulation of amyloid beta (A,) protein in senile plaques and hyperphosphorylated tau in neurofibrillary tangles. Previously, we have shown that saturated free fatty acids (FFAs), palmitic and stearic acids, caused increased amyloidogenesis and tau hyperphosphorylaion in primary rat cortical neurons. These FFA-induced effects observed in neurons were found to be mediated by astroglial FFA metabolism. Therefore, in the present study we investigated the basic mechanism relating astroglial FFA metabolism and AD-like changes observed in neurons. We found that palmitic acid significantly increased de-novo synthesis of ceramide in astroglia, which in turn was involved in inducing both increased production of the A, protein and hyperphosphorylation of the tau protein. Increased amyloidogenesis and hyperphoshorylation of tau lead to formation of the two most important pathophysiological characteristics associated with AD, A, or senile plaques and neurofibrillary tangles, respectively. In addition to these pathophysiological changes, AD is also characterized by certain metabolic changes; abnormal cerebral glucose metabolism is one of the distinct characteristics of AD. In this context, we found that palmitic acid significantly decreased the levels of astroglial glucose transporter (GLUT1) and down-regulated glucose uptake and lactate release by astroglia. Our present data establish an underlying mechanism by which saturated fatty acids induce AD-associated pathophysiological as well as metabolic changes, placing ,astroglial fatty acid metabolism' at the center of the pathogenic cascade in AD. [source] Withanoside IV and its active metabolite, sominone, attenuate A,(25,35)-induced neurodegenerationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2006Tomoharu Kuboyama Abstract At the present, medication of dementia is limited to symptomatic treatments such as the use of cholinesterase inhibitors. To cure dementia completely, that is regaining neuronal function, reconstruction of neuronal networks is necessary. Therefore, we have been exploring antidementia drugs based on reconstructing neuronal networks in the damaged brain and found that withanoside IV (a constituent of Ashwagandha; the root of Withania somnifera) induced neurite outgrowth in cultured rat cortical neurons. Oral administration of withanoside IV (10 µmol/kg/day) significantly improved memory deficits in A,(25,35)-injected (25 nmol, i.c.v.) mice and prevented loss of axons, dendrites, and synapses. Sominone, an aglycone of withanoside IV, was identified as the main metabolite after oral administration of withanoside IV. Sominone (1 µm) induced axonal and dendritic regeneration and synaptic reconstruction significantly in cultured rat cortical neurons damaged by 10 µm A,(25,35). These data suggest that orally administrated withanoside IV may ameliorate neuronal dysfunction in Alzheimer's disease and that the active principle after metabolism is sominone. [source] GABA and glycine are protective to mature but toxic to immature rat cortical neurons under hypoxiaEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2005Peng Zhao Abstract Although recent studies suggest that ,-aminobutyric acid (GABA) and glycine may be ,inhibitory' to mature neurons, but ,excitatory' to immature neurons under normoxia, it is unknown whether inhibitory neurotransmitters are differentially involved in neuronal response to hypoxia in immature and mature neurons. In the present study, we exposed rat cortical neurons to hypoxia (1% O2) and examined the effects of three major inhibitory neurotransmitters (GABA, glycine and taurine) on the hypoxic neurons at different neuronal ages [days in vitro (DIV)4,20]. Our data showed that the cortical neurons expressed both GABAA and glycine receptors with differential developmental profiles. GABA (10,2000 µm) was neuroprotective to hypoxic neurons of DIV20, but enhanced hypoxic injury in neurons of <,DIV20. Glycine at low concentrations (10,100 µm) exhibited a similar pattern to GABA. However, higher concentrations of glycine (1000,2000 µm) for long-term exposure (48,72 h) displayed neuroprotection at all ages (DIV4,20). Taurine (10,2000 µm), unlike GABA and glycine, displayed protection only in DIV4 neurons, and was slightly toxic to neurons >,DIV4. In comparison with delta-opioid receptor (DOR)-induced protection in DIV20 neurons exposed to 72 h of hypoxia, glycine-induced protection was weaker than that of DOR but stronger than that of GABA and taurine. These data suggest that the effects of the inhibitory neurotransmitters on hypoxic cortical neurons are age-dependent, with GABA and glycine being neurotoxic to immature neurons and neuroprotective to mature neurons. [source] LIM-only protein 4 interacts directly with the repulsive guidance molecule A receptor NeogeninJOURNAL OF NEUROCHEMISTRY, Issue 2 2008Gregor Schaffar Abstract Repulsive guidance molecule A (RGM A) was recently described as a potent inhibitor of neuroregeneration in a rat spinal cord injury model. The receptor mediating RGM A's repulsive activity was shown to be Neogenin, a member of the Deleted in Colorectal Cancer (DCC) family of netrin receptors. Binding of RGM A to Neogenin induces activation of the small GTPase RhoA and of its effector Rho-kinase by an unknown mechanism. Here we show, that the cytoplasmic tail of Neogenin interacts directly with the transcriptional coactivator LIM domain only 4 (LMO4) in human SH-SY5Y cells, human Ntera neurons, and in embryonic rat cortical neurons. RGM A binding to Neogenin but not binding of Netrin-1, induces release of LMO4 from Neogenin. Down-regulation of LMO4 neutralizes the repulsive activity of RGM A in neuronal cell lines and embryonic rat cortical neurons and prevents RhoA activation. These results show for the first time that an interaction of Neogenin with LMO4 is involved in the RGM A , Neogenin signal transduction pathway for RhoA activation. [source] CaM kinase II and protein kinase C activations mediate enhancement of long-term potentiation by nefiracetam in the rat hippocampal CA1 regionJOURNAL OF NEUROCHEMISTRY, Issue 3 2008Shigeki Moriguchi Abstract Nefiracetam is a pyrrolidine-related nootropic drug exhibiting various pharmacological actions such as cognitive-enhancing effect. We previously showed that nefiracetam potentiates NMDA-induced currents in cultured rat cortical neurons. To address questions whether nefiracetam affects NMDA receptor-dependent synaptic plasticity in the hippocampus, we assessed effects of nefiracetam on NMDA receptor-dependent long-term potentiation (LTP) by electrophysiology and LTP-induced phosphorylation of synaptic proteins by immunoblotting analysis. Nefiracetam treatment at 1,1000 nM increased the slope of fEPSPs in a dose-dependent manner. The enhancement was associated with increased phosphorylation of ,-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor through activation of calcium/calmodulin-dependent protein kinase II (CaMKII) without affecting synapsin I phosphorylation. In addition, nefiracetam treatment increased PKC, activity in a bell-shaped dose,response curve which peaked at 10 nM, thereby increasing phosphorylation of myristoylated alanine-rich protein kinase C substrate and NMDA receptor. Nefiracetam treatment did not affect protein kinase A activity. Consistent with the bell-shaped PKC, activation, nefiracetam treatment enhanced LTP in the rat hippocampal CA1 region with the same bell-shaped dose,response curve. Furthermore, nefiracetam-induced LTP enhancement was closely associated with CaMKII and PKC, activation with concomitant increases in phosphorylation of their endogenous substrates except for synapsin I. These results suggest that nefiracetam potentiates AMPA receptor-mediated fEPSPs through CaMKII activation and enhances NMDA receptor-dependent LTP through potentiation of the post-synaptic CaMKII and protein kinase C activities. Together with potentiation of nicotinic acetylcholine receptor function, nefiracetam-enhanced AMPA and NMDA receptor functions likely contribute to improvement of cognitive function. [source] Insensitivity to glutamate neurotoxicity mediated by NMDA receptors in association with delayed mitochondrial membrane potential disruption in cultured rat cortical neuronsJOURNAL OF NEUROCHEMISTRY, Issue 5 2008Yuki Kambe Abstract We have attempted to elucidate mechanisms underlying differential vulnerability to glutamate (Glu) using cultured neurons prepared from discrete structures of embryonic rat brains. Brief exposure to Glu led to a significant decrease in the mitochondrial activity in hippocampal neurons cultured for 9 or 12 days at 10 ,M to 1 mM with an apoptosis-like profile, without markedly affecting that in cortical neurons. Brief exposure to Glu also increased lactate dehydrogenase release along with a marked decrease in the number of cells immunoreactive for a neuronal marker protein in hippocampal, but not cortical, neurons. Similar insensitivity was seen to the cytotoxicity by NMDA, but not to that by tunicamycin, 2,4-dinitrophenol, hydrogen peroxide or A23187, in cortical neurons. However, NMDA was more efficient in increasing intracellular free Ca2+ levels in cortical neurons than in hippocampal neurons. Antagonists for neuroprotective metabotropic Glu receptors failed to significantly affect the insensitivity to Glu, while NMDA was more effective in disrupting mitochondrial membrane potentials in hippocampal than cortical neurons. These results suggest that cortical neurons would be insensitive to the apoptotic neurotoxicity mediated by NMDA receptors through a mechanism related to mitochondrial membrane potentials, rather than intracellular free Ca2+ levels, in the rat brain. [source] The Kv4.2 mediates excitatory activity-dependent regulation of neuronal excitability in rat cortical neuronsJOURNAL OF NEUROCHEMISTRY, Issue 3 2008Bin Shen Abstract Neuronal excitability can cooperate with synaptic transmission to control the information storage. This regulation of neuronal plasticity can be affected by alterations in neuronal inputs and accomplished by modulation of voltage-dependent ion channels. In this study, we report that enhanced excitatory input negatively regulated neuronal excitability. Enhanced excitatory input by glutamate, electric field stimulation or high K+ increased transient outward K+ current, whereas did not affect the delayed rectifier K+ current in rat cultured cortical neurons. Both the voltage-dependent K+ channel 4.2 and 4.3 subunits contributed to the increase. The increase in the K+ current density by Kv4.2 was ascribed to its cytoplasmic membrane translocation, which was mediated by NMDA type of glutamate receptor. Furthermore, enhanced excitatory input inhibited neuronal excitability. Taken together, our results suggest that excitatory neurotransmission affects neuronal excitability via the regulation of the K+ channel membrane translocation. [source] Neuroprotective actions of noradrenaline: effects on glutathione synthesis and activation of peroxisome proliferator activated receptor deltaJOURNAL OF NEUROCHEMISTRY, Issue 5 2007Jose L. M. Madrigal Abstract The endogenous neurotransmitter noradrenaline (NA) can protect neurons from the toxic consequences of various inflammatory stimuli, however the exact mechanisms of neuroprotection are not well known. In the current study, we examined neuroprotective effects of NA in primary cultures of rat cortical neurons. Exposure to oligomeric amyloid beta (A,) 1-42 peptide induced neuronal damage revealed by increased staining with fluorojade, and toxicity assessed by LDH release. A,-dependent neuronal death did not involve neuronal expression of the inducible nitric oxide synthase 2 (NOS2), since A, did not induce nitrite production from neurons, LDH release was not reduced by co-incubation with NOS2 inhibitors, and neurotoxicity was similar in wildtype and NOS2 deficient neurons. Co-incubation with NA partially reduced A,-induced neuronal LDH release, and completely abrogated the increase in fluorojade staining. Treatment of neurons with NA increased expression of ,-glutamylcysteine ligase, reduced levels of GSH peroxidase, and increased neuronal GSH levels. The neuroprotective effects of NA were partially blocked by co-treatment with an antagonist of peroxisome proliferator activated receptors (PPARs), and replicated by incubation with a selective PPARdelta (PPAR,) agonist. NA also increased expression and activation of PPAR,. Together these data demonstrate that NA can protect neurons from A,-induced damage, and suggest that its actions may involve activation of PPAR, and increases in GSH production. [source] Robust stimulation of TrkB induces delayed increases in BDNF and Arc mRNA expressions in cultured rat cortical neurons via distinct mechanismsJOURNAL OF NEUROCHEMISTRY, Issue 2 2007Makoto Yasuda Abstract In cultures of rat cortical neurons, we found that stimulation of tyrosine receptor kinase B (TrkB) with brain-derived neurotrophic factor (BDNF) induced a biphasic expression of BDNF exon IV,IX mRNA, which became obvious 1,3 h (primary induction) and 24,72 h (delayed induction) after the stimulation, and characterized the delayed induction in relation to the mRNA expression of activity-regulated cytoskeleton-associated protein (Arc). Withdrawal of BDNF from the medium after stimulation for 3 h allowed the delayed induction, which was caused at the transcriptional level and dependent upon the initial contact between exogenously added BDNF and TrkB, the effect of which was time- and dose-dependent. The primary induction was controlled by the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) whereas the secondary induction by the calcium (Ca2+) signaling pathway. The enhanced Arc or Zif268 mRNA expression was controlled by activation of the ERK/MAPK pathway, both of which were repressed by blocking the binding of endogenously synthesized BDNF to TrkB. Thus, robust stimulation of TrkB autonomously induces delayed BDNF mRNA expression in an activity-dependent manner in rat cortical neurons, resulting in the stimulation of Arc mRNA expression through endogenously synthesized BDNF, the process being orchestrated by the Ca2+ and ERK/MAPK signaling pathways. [source] Soluble oligomers from a non-disease related protein mimic A,-induced tau hyperphosphorylation and neurodegenerationJOURNAL OF NEUROCHEMISTRY, Issue 2 2007Marcelo N. N. Vieira Abstract Protein aggregation and amyloid accumulation in different tissues are associated with cellular dysfunction and toxicity in important human pathologies, including Alzheimer's disease and various forms of systemic amyloidosis. Soluble oligomers formed at the early stages of protein aggregation have been increasingly recognized as the main toxic species in amyloid diseases. To gain insight into the mechanisms of toxicity instigated by soluble protein oligomers, we have investigated the aggregation of hen egg white lysozyme (HEWL), a normally harmless protein. HEWL initially aggregates into ,-sheet rich, roughly spherical oligomers which appear to convert with time into protofibrils and mature amyloid fibrils. HEWL oligomers are potently neurotoxic to rat cortical neurons in culture, while mature amyloid fibrils are little or non-toxic. Interestingly, when added to cortical neuronal cultures HEWL oligomers induce tau hyperphosphorylation at epitopes that are characteristically phosphorylated in neurons exposed to soluble oligomers of the amyloid-, peptide. Furthermore, injection of HEWL oligomers in the cerebral cortices of adult rats induces extensive neurodegeneration in different brain areas. These results show that soluble oligomers from a non-disease related protein can mimic specific neuronal pathologies thought to be induced by soluble amyloid-, peptide oligomers in Alzheimer's disease and support the notion that amyloid oligomers from different proteins may share common structural determinants that would explain their generic cytotoxicities. [source] Neuroprotection by stem cell factor in rat cortical neurons involves AKT and NF,BJOURNAL OF NEUROCHEMISTRY, Issue 1 2005Krishnan M. Dhandapani Abstract Stem cell factor (SCF) is a highly expressed cytokine in the central nervous system. In the present study, we demonstrate a neuroprotective role for SCF and its tyrosine kinase receptor, c-kit, against camptothecin-induced apoptosis and glutamate excitotoxicity in rat cortical neurons. This protection was blocked by pharmacological or molecular inhibition of either the MEK/ERK or PI3K/Akt signaling pathways. The importance of these pathways was further confirmed by the activation of both ERK, in a MEK-dependent manner, and Akt, via PI3K. Activation of Akt increased the binding of the p50 and p65 subunits of NF,B, which was also important for neuroprotection. Akt inhibition prevented NF,B binding, suggesting a role for Akt in SCF-induced NF,B. Pharmacological inhibition of NF,B or dominant negative I,B also prevented neuroprotection by SCF. SCF up-regulated the anti-apoptotic genes, bcl-2 and bcl-xL in an NF,B-dependent manner. Together, these findings demonstrate a neuroprotective role for SCF in cortical neurons, an effect that was mediated by Akt and ERK, as well as NF,B-mediated gene transcription. SCF represents a novel therapeutic target in the treatment of neurodegenerative disease. [source] Blockade by ferrous iron of Ca2+ influx through N -methyl- d -aspartate receptor channels in immature cultured rat cortical neuronsJOURNAL OF NEUROCHEMISTRY, Issue 1 2002Noritaka Nakamichi Abstract Rat cortical neurons cultured for 3 days in vitro were loaded with the fluorescent indicator fluo-3 for assessment of intracellular free calcium ion (Ca2+) concentrations with the aid of a confocal laser-scanning microscope. In the absence of added MgCl2, the addition of NMDA induced a rapid but sustained increase in the number of fluorescent neurons in a concentration-dependent manner at a concentration range of 1,100 µm with the increase by KCl being transient. The addition of FeCl2, but not FeCl3, markedly inhibited the increase by NMDA in a reversible manner at concentrations of 10,200 µm, without affecting that by KCl. Extensive analyses revealed clear differentiation between inhibitions by ferrous iron and other channel blockers known to date. The inhibition by FeCl2 was completely prevented by the addition of two different iron chelators. Exposure to NMDA alone did not lead to cell death in immature cultured neurons, however, while further addition of FeCl2 invariably induced neuronal cell death 24 h after exposure. These results give support to our previous proposal that NMDA receptor complex may contain a novel site sensitive to blockade by ferrous iron in rat brain. [source] A Nonfibrillar Form of the Fusogenic Prion Protein Fragment [118-135] Induces Apoptotic Cell Death in Rat Cortical NeuronsJOURNAL OF NEUROCHEMISTRY, Issue 6 2000Thierry Pillot Abstract: Neuronal loss is a salient feature of prion diseases.However, its cause and mechanism, particularly its relationship with theaccumulation and precipitation of the pathogenic, protease-resistant isoformPrPSc of the cellular prion protein PrPC, are still anenigma. Several studies suggest that neuronal loss could occur through aprocess of programmed cell death, which is consistent with the lack ofinflammation in these conditions. By analogy with the pathological eventsoccurring during the development of Alzheimer's disease, controversies stillexist regarding the relationship between amyloidogenesis, prion aggregation,and neuronal loss. We recently demonstrated that a prion protein fragment(118-135) displayed membrane-destabilizing properties and was able to induce,in a nonfibrillar form, the fusion of unilamellar liposomes. To unravel themechanism of prion protein neurotoxicity, we characterize the effects of thehuman Pr[118-135] peptide on rat cortical neurons. We demonstrate that lowconcentrations of the Pr[118-135] peptide, in a nonfibrillar form, induce atime- and dose- dependent apoptotic cell death, including caspase activation,DNA condensation, and fragmentation. This toxicity might involve oxidativestress, because antioxidant molecules, such as probucol and propyl gallate,protect neurons against prion peptide toxicity. By contrast, a nonfusogenicvariant Pr[118-135, 0°] peptide, which displays the same amino acidcomposition but several amino acid permutations, is not toxic to corticalneurons, which emphasizes the critical role of the fusogenic properties of theprion peptide in its neurotoxicity. Taken together, our results suggest thatthe interaction between the Pr[118-135] peptide and the plasma membrane ofneurons might represent an early event in a cascade leading toneurodegeneration. [source] The small heat shock protein Hsp27 protects cortical neurons against the toxic effects of ,-amyloid peptideJOURNAL OF NEUROSCIENCE RESEARCH, Issue 14 2009Michael King Abstract Neurofibrillary tangles and amyloid plaques are considered to be hallmarks of Alzheimer's disease (AD), and the toxic effects of amyloid-, peptide (A,) lead to activation of stress-related signaling and neuronal loss. The small heat shock protein Hsp27 is reported to be increased in AD brains and to accumulate in plaques, but whether this represents a potentially protective response to stress or is part of the disease process is not known. We hypothesized that increased expression of Hsp27 in neurons can promote neuronal survival and stabilize the cytoskeleton in the face of A, exposure. By using neonatal rat cortical neurons, we investigated the potential role of Hsp27 in neuronal cultures in the presence or absence of A,. We initially tested whether a heat stress (HS) would be sufficient to induce endogenous Hsp27 expression. HS not only did not result in neuronal Hsp27 up-regulation but made the cells more vulnerable to A, exposure. We then used cDNA transfection to overexpress EGFP-Hsp27 (or the empty vector) in cultures and then assessed neuronal survival and growth. Transfected neurons appeared healthy and had robust neuritic outgrowth. A, treatment induced significant cell death by 48,72 hr in nontransfected and empty-vector-expressing cultures. In contrast, cultures expressing Hsp27 did not display significant apoptosis. Our results show that Hsp27-expressing neurons were selectively protected against the deleterious effects of A, treatment; neuronal degeneration was prevented, and A,-induced alterations in mitochondrial size were attenuated. We also demonstrate that Hsp27 expression can enhance neurite growth in cortical neurons compared with control vector-transfected cells. Overall, our study provides new evidence that Hsp27 can provide a protective influence in primary cortical neurons in the face of toxic concentrations of amyloid. © 2009 Wiley-Liss, Inc. [source] Neuroprotective effect of hypothermia at defined intraischemic time courses in cortical culturesJOURNAL OF NEUROSCIENCE RESEARCH, Issue 6 2001Sriranganathan Varathan Abstract Many experimental and clinical studies have shown that hypothermia confers cerebroprotective benefits against ischemic insults. Because of the many conflicting reports on hypothermic neuroprotection, we undertook this cellular study to identify the optimal temperature or a range of temperatures for maximal neuroprotection at different times (6,24 hr) during ischemic insults. Cultured Wistar rat cortical neurons were exposed to oxygen deprivation at defined times and temperatures (37°C normothermia, 32°C mild hypothermia, 27°C moderate hypothermia, 22°C deep hypothermia, and 17°C profound hypothermia). The survival rate of neurons was evaluated by assessing viable neurons on photomicrographs. The normothermic group demonstrated a significantly lower survival rate of cultured neurons (6 hr, 80.3% ± 2.7%; 12 hr, 56.1% ± 2.1%; 18 hr, 34.2% ± 1%; 24 hr, 18.1% ± 2.2%) compared to hypothermic groups (P < 0.001). The survival rate for the profound hypothermic group was significantly reduced (P < 0.01) compared to other hypothermic groups (at 17°C: 12 hr, 85.9% ± 2.5%, 18 hr, 74.7% ± 3.7%, 24 hr, 58.7% ± 2.7%). Almost equal survival rates were observed among mild, moderate, and deep hypothermic groups following <18 hr exposure to hypoxia, but the deep hypothermic group showed a significantly higher survival rate (84.1% ± 1.6%; P < 0.001) when subjected to hypoxia for 24 hr. In conclusion, hypothermia offers marked neuroprotection against hypoxia, but attenuation of neuronal cell death was less with profound hypothermia compared to mild, moderate, and deep hypothermia. Deep hypothermia affords maximal protection of neurons compared to mild and moderate hypothermia during long-lasting hypoxia (>18 hr). J. Neurosci. Res. 65:583,590, 2001. © 2001 Wiley-Liss, Inc. [source] Design and synthesis of new trehalose-conjugated pentapeptides as inhibitors of A,(1,42) fibrillogenesis and toxicity,JOURNAL OF PEPTIDE SCIENCE, Issue 3 2009Paolo De Bona Abstract Aggregation of the amyloid A, peptide and its accumulation into insoluble deposits (plaques) are believed to be the main cause of neuronal dysfunction associated with Alzheimer's disease (AD); small molecules that can interfere with the A, amyloid fibril formation are therefore of interest for a potential therapeutic strategy. Three new trehalose-conjugated peptides of the well known ,-sheet breaker peptide iA,5p, were synthesized. The disaccharide was covalently attached to different sites of the LPFFD peptide chain, i.e. at the N-terminus, C-terminus or at the Asp side chain. CD spectroscopy in different solvents was used to assess changes in the peptide conformation of these compounds. The effects of these glycopeptides on the self-assembly and morphology of A, aggregates were investigated by ThT fluorescence assay and dynamic Scanning Force Microscopy, respectively. All the synthesized compounds were tested as inhibitors of A, toxicity toward pure cultures of rat cortical neurons. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd. [source] Pharmacological profile of an essential oil derived from Melissa officinalis with anti-agitation properties: focus on ligand-gated channelsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2008Sawsan Abuhamdah A dual radioligand binding and electrophysiological study, focusing on a range of ligand-gated ion channels, was performed with a chemically-validated essential oil derived from Melissa officinalis (MO), which has shown clinical benefit in treating agitation. MO inhibited binding of [35S] t -butylbicyclophosphorothionate (TBPS) to the rat forebrain gamma-aminobutyric acid (GABA)A receptor channel (apparent IC50 0.040±0.001 mg mL,1), but had no effect on N -methyl- d -aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropianate (AMPA) or nicotinic acetylcholine receptors. Electrophysiological analyses with primary cultures of rat cortical neurons demonstrated that MO reversibly inhibited GABA-induced currents in a concentration-dependent manner (0.01,1 mg mL,1), whereas no inhibition of NMDA- or AMPA-induced currents was noted. Interestingly, MO elicited a significant dose-dependent reduction in both inhibitory and excitatory transmission, with a net depressant effect on neurotransmission (in contrast to the classical GABAA antagonist picrotoxinin which evoked profound epileptiform burst firing in these cells). The anti-agitation effects in patients and the depressant effects of MO in in-vitro we report in neural membranes are unlikely to reflect a sedative interaction with any of the ionotropic receptors examined here. [source] Neuroprotective effect of luteolin on amyloid , protein (25,35)-induced toxicity in cultured rat cortical neuronsPHYTOTHERAPY RESEARCH, Issue S1 2010Hao-Yuan Cheng Abstract The present study was carried out to investigate the neuroprotective effect of luteolin on amyloid , (A,) (25,35)-induced neurotoxicity using cultured rat cortical neurons. After exposure of primary cultures of rat cortical cells to 10 ,M A, (25,35) for 48 h, cortical cell cultures exhibited marked apoptotic death. Pretreatment with luteolin (1, 10 ,M) significantly protected cortical cell cultures against A, (25,35)-induced toxicity. Luteolin (1, 10 ,M) showed a concentration-dependent inhibition on 10 ,M A, (25,35)-induced apoptotic neuronal death, as assessed by MTT assay. Furthermore, luteolin reduced apoptotic characteristics by DAPI staining. For Western blot analysis, the results showed that the protective effect of luteolin on A, (25,35)-induced neurotoxicity was mediated by preventing of ERK-p, JNK, JNK-p, P38-p and caspase 3 activations in rat primary cortical cultures. Taken together, the results suggest that luteolin prevents A, (25,35)-induced apoptotic neuronal death through inhibiting the protein level of JNK, ERK and p38 MAP kinases and caspase 3 activations. Copyright © 2009 John Wiley & Sons, Ltd. [source] Protective effect of Toki-shakuyaku-san on amyloid ,25,35 -induced neuronal damage in cultured rat cortical neuronsPHYTOTHERAPY RESEARCH, Issue 5 2005Nobuaki Egashira Abstract Amyloid , protein (A,) is the major component of senile plaques, the pathological hallmark of the neurodegeneration associated with Alzheimer's disease (AD). This study investigated the effect of Toki-shakuyaku-san (TSS), a traditional medicine, on A,25,35 -induced neuronal death and lipid peroxidation assessed by measuring lactate dehydrogenase (LDH) and malondialdehyde (MDA), respectively. A,25,35 at 10 µM induced neuronal damage and increased the LDH and MDA. TSS at concentrations of 100 and 300 µg/mL significantly reduced the A,25,35 -induced neuronal death and the lipid peroxidation. These results suggest that TSS has a protective effect against A,25,35 -induced neuronal damage. TSS may be beneficial for the treatment of AD. Copyright © 2005 John Wiley & Sons, Ltd. [source] Developmental change in GABAA receptor desensitization kinetics and its role in synapse function in rat cortical neuronsTHE JOURNAL OF PHYSIOLOGY, Issue 1 2000Bruce Hutcheon We examined the maturation of GABAA receptor synapses in cortical pyramidal neurons cultured from embryonic rats. The decay kinetics of GABAA receptor-mediated miniature postsynaptic currents (mPSCs) were compared with those of responses evoked by GABA in excised membrane patches. Fast perfusion of 1 or 10 mM GABA on membrane patches evoked currents with different desensitizing time courses in young and old neurons. For neurons older than 4 days in vitro (DIV), GABAA currents had a fast component of desensitization (median , 3 ms) seldom seen in patches from younger neurons. In contrast, mPSCs exhibited a substantial fast component of decay at 2,4 DIV that became more prominent with further development although the median value of its time constant remained unchanged. The selective ,3 subunit positive modulator SB-205384 had no effect on mPSCs at any time in vitro but potentiated extrasynaptic activity. This suggests that synapse maturation does not proceed by a gradual exchange of early embryonic GABAA receptor subforms for adult forms. At all ages, the kinetic properties of mPSCs were heterogeneous. This heterogeneity extended to the level of mPSCs from single neurons and may be a normal aspect of synaptic functioning. These results suggest that inhibitory synapses in developing neurons are capable of selectively capturing GABAA receptors having fast desensitization kinetics. This functional preference probably reflects the developmental turning point from an inwardly looking trophic capacity of embryonic GABAA receptors to a role concerned with information processing. [source] Acute exposure to low-level CW and GSM-modulated 900 MHz radiofrequency does not affect Ba2+ currents through voltage-gated calcium channels in rat cortical neuronsBIOELECTROMAGNETICS, Issue 8 2007Daniela Platano Abstract We have studied the non-thermal effects of radiofrequency (RF) electromagnetic fields (EMFs) on Ba2+ currents () through voltage-gated calcium channels (VGCC), recorded in primary cultures of rat cortical neurons using the patch-clamp technique. To assess whether low-level acute RF field exposure could modify the amplitude and/or the voltage-dependence of , Petri dishes containing cultured neurons were exposed for 1,3 periods of 90 s to 900 MHz RF-EMF continuous wave (CW) or amplitude-modulated according to global system mobile communication standard (GSM) during whole-cell recording. The specific absorption rates (SARs) were 2 W/kg for CW and 2 W/kg (time average value) for GSM-modulated signals, respectively. The results obtained indicate that single or multiple acute exposures to either CW or GSM-modulated 900 MHz RF-EMFs do not significantly alter the current amplitude or the current,voltage relationship of , through VGCC. Bioelectromagnetics 28:599,607, 2007. © 2007 Wiley-Liss, Inc. [source] Effects of mood stabilizers on the inhibition of adenylate cyclase via dopamine D2 -like receptorsBIPOLAR DISORDERS, Issue 3 2007Liliana P Montezinho Objective:, The mood stabilizing drugs lithium, carbamazepine and valproate modulate brain adenosine monophosphate (cAMP) levels, which are assumed to be elevated in bipolar disorder patients. The aim of this work was to investigate how these three mood stabilizing agents affect the regulation of cAMP levels by dopamine D2 -like receptors in vitro in rat cortical neurons in culture and in vivo in the rat prefrontal cortex. Methods:, The production of cAMP was measured in the cultured cortical neurons or in microdialysis samples collected from the prefrontal cortex of freely moving rats using the [8- 3H] and [125I] radioimmunoassay kits. Results:,In vitro and in vivo data showed that the treatment with the mood stabilizing drugs had no effect on basal cAMP levels in vitro, but had differential effects in vivo. Direct stimulation of adenylate cyclase (AC) with forskolin increased cAMP levels both in vitro and in vivo, and this effect was significantly inhibited by all three mood stabilizers. Activation of dopamine D2 -like receptors with quinpirole partially inhibited forskolin-induced increase in cAMP in untreated cultures, but no effect was observed in cortical neuron cultures treated with the mood stabilizing drugs. Similar results were obtained by chronic treatment with lithium and valproate in the prefrontal cortex in vivo. However, surprisingly, in carbamazepine-treated rats the activation of dopamine D2 -like receptors enhanced the responsiveness of AC to subsequent activation by forskolin, possibly as a consequence of chronic inhibition of the activity of the enzyme. Conclusions:, It was shown that each of these drugs affects basal- and forskolin-evoked cAMP levels in a distinct way, resulting in differential responses to dopamine D2 -like receptors activation. [source] Promotion of axonal maturation and prevention of memory loss in mice by extracts of Astragalus mongholicusBRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2006C Tohda Background and purpose: Neurons with atrophic neurites may remain alive and therefore may have the potential to regenerate even when neuronal death has occurred in some parts of the brain. This study aimed to explore effects of drugs that can facilitate the regeneration of neurites and the reconstruction of synapses even in severely damaged neurons. Experimental approach: We investigated the effects of extracts of Astragalus mongholicus on the cognitive defect in mice caused by injection with the amyloid peptide A,(25-35). We also examined the effect of the extract on the regeneration of neurites and the reconstruction of synapses in cultured neurons damaged by A,(25-35). Key results: A. mongholicus extract (1 g kg,1 day,1 for 15 days, p.o.) reversed A,(25-35)-induced memory loss and prevented the loss of axons and synapses in the cerebral cortex and hippocampus in mice. Treatment with A,(25-35) (10 ,M) induced axonal atrophy and synaptic loss in cultured rat cortical neurons. Subsequent treatment with A. mongholicus extract (100 ,g/ml) resulted in significant axonal regeneration, reconstruction of neuronal synapses, and prevention of A,(25-35)-induced neuronal death. Similar extracts of A. membranaceus had no effect on axonal atrophy, synaptic loss, or neuronal death. The major known components of the extracts (astragalosides I, II, and IV) reduced neurodegeneration, but the activity of the extracts did not correlate with their content of these three astragalosides. Conclusion and implications: A. mongholicus is an important candidate for the treatment of memory disorders and the main active constituents may not be the known astragalosides. British Journal of Pharmacology (2006) 149, 532,541. doi:10.1038/sj.bjp.0706865 [source] | |||||||||||||