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Rat Hippocampal Neurons (rat + hippocampal_neuron)
Kinds of Rat Hippocampal Neurons Selected AbstractsEthanol Inhibits Muscarinic Receptor-Induced Axonal Growth in Rat Hippocampal NeuronsALCOHOLISM, Issue 11 2009Kathryn L. VanDeMark Background:, In utero alcohol exposure can lead to fetal alcohol spectrum (FAS) disorders characterized by cognitive and behavioral deficits. In vivo and in vitro studies have shown that ethanol alters neuronal development. One mechanism through which ethanol has been shown to exert its effects is the perturbation of activated signaling cascades. The cholinergic agonist carbachol has been shown to induce axonal outgrowth through intracellular calcium mobilization, protein kinase C (PKC) activation, and ERK1/2 phosphorylation. This study investigated the effect of ethanol on the differentiation of rat hippocampal pyramidal neurons induced by carbachol as a possible mechanism involved in the developmental neurotoxicity of ethanol. Methods:, Prenatal rat hippocampal pyramidal neurons were treated with ethanol (50 to 75 mM) in the presence or absence of carbachol for 24 hours. Neurite outgrowth was assessed spectrophotometrically; axonal length was measured in neurons fixed and immunolabeled with the neuron-specific ,III tubulin antibody; cytotoxicity was analyzed using the thiazolyl blue tetrazolium bromide assay. The effect of ethanol on carbachol-stimulated intracellular calcium mobilization was assessed utilizing the fluorescent calcium probe, Fluo-3AM. The PepTag® assay for nonradioactive detection of PKC from Promega was used to measure PKC activity, and ERK1/2 activation was determined by densitometric analysis of Western blots probed for phospo-ERK1/2. Results:, Ethanol treatment (50 to 75 mM) caused an inhibition of carbachol-induced axonal growth, without affecting neuronal viability. Neuron treatment for 15 minutes with ethanol did not inhibit the carbachol-stimulated rise in intracellular calcium, while inhibiting PKC activity at the highest tested concentration and ERK1/2 phosphorylation at both the concentrations used in this study. On the other hand, neuron treatment for 24 hours with ethanol significantly inhibited carbachol-induced increase in intracellular calcium. Conclusions:, Ethanol inhibited carbachol-induced neurite outgrowth by inhibiting PKC and ERK1/2 activation. These effects may be, in part, responsible for some of the cognitive deficits associated with in utero alcohol exposure. [source] (S)-N-[1-(4-Cyclopropylmethyl-3,4-dihydro-2H-benzo [1,4]oxazin-6-yl)-ethyl]-3-(2-fluoro-phenyl)-acrylamide Is a Potent and Efficacious KCNQ2 Opener which Inhibits Induced Hyperexcitability of Rat Hippocampal Neurons.CHEMINFORM, Issue 31 2004Yong-Jin Wu Abstract For Abstract see ChemInform Abstract in Full Text. [source] The heterogeneous distribution of functional synaptic connections in rat hippocampal dissociated neuron culturesELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 6 2009Suguru N. Kudoh Abstract The dynamics of functional synaptic connections are critical for information processing systems in the brain, such as perception and learning. Using rat hippocampal cells cultured on multielectrode arrays, we investigated the spatiotemporal pattern of spontaneous action potentials. The neurons developed connections and a characteristic high-frequency bursting (HFB) activity was observed transiently. After the period of HFB activity, the distribution of spontaneous activity changed drastically with the appearance of neurons with frequent electrical activity and neurons with little activity in the network. The functional connections of all the combinations of recorded spike trains were estimated and depicted simultaneously in a Connection Map. This map revealed that each culture contained hublike neurons with many functional connections, suggesting that the cultures of dissociated rat hippocampal neurons on multielectrode arrays formed heterogeneous networks of functional connections. In addition, the functional connections were drastically reorganized after the induction of synaptic potentiation, and novel hub neurons emerged. These results indicate that spontaneous activity is enough to construct dynamic assemblies of neurons connected to each other by functional synaptic connections, and that synaptic potentiation can induce reorganization of such assemblies of neurons. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(6): 41,49, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10063 [source] The type 1 cannabinoid receptor is highly expressed in embryonic cortical projection neurons and negatively regulates neurite growth in vitroEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2008Tania Vitalis Abstract In the rodent and human embryonic brains, the cerebral cortex and hippocampus transiently express high levels of type 1 cannabinoid receptors (CB1Rs), at a developmental stage when these areas are composed mainly of glutamatergic neurons. However, the precise cellular and subcellular localization of CB1R expression as well as effects of CB1R modulation in this cell population remain largely unknown. We report that, starting from embryonic day 12.5, CB1Rs are strongly expressed in both reelin-expressing Cajal-Retzius cells and newly differentiated postmitotic glutamatergic neurons of the mouse telencephalon. CB1R protein is localized first to somato-dendritic endosomes and at later developmental stages it localizes mostly to developing axons. In young axons, CB1Rs are localized both to the axolemma and to large, often multivesicular endosomes. Acute maternal injection of agonist CP-55940 results in the relocation of receptors from axons to somato-dendritic endosomes, indicating the functional competence of embryonic CB1Rs. The adult phenotype of CB1R expression is established around postnatal day 5. By using pharmacological and mutational modulation of CB1R activity in isolated cultured rat hippocampal neurons, we also show that basal activation of CB1R acts as a negative regulatory signal for dendritogenesis, dendritic and axonal outgrowth, and branching. Together, the overall negative regulatory role in neurite development suggests that embryonic CB1R signaling may participate in the correct establishment of neuronal connectivity and suggests a possible mechanism for the development of reported glutamatergic dysfunction in the offspring following maternal cannabis consumption. [source] Translation of an integral membrane protein in distal dendrites of hippocampal neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2005Jeffrey C. Grigston Abstract Maintenance of synaptic plasticity requires protein translation. Because changes in synaptic strength are regulated at the level of individual synapses, a mechanism is required for newly translated proteins to specifically and persistently modify only a subset of synapses. Evidence suggests this may be accomplished through local translation of proteins at or near synapses in response to plasticity-inducing patterns of activity. A number of proteins important for synaptic function are integral membrane proteins, which require a specialized group of organelles, proteins and enzymatic activities for proper synthesis. Dendrites appear to contain machinery necessary for the proper production of these proteins, and mRNAs for integral membrane proteins have been found localized to dendrites. Experiments are described that investigate the local translation of membrane proteins in the dendrites of cultured rat hippocampal neurons, using fluorescence recovery after photobleaching. Neurons were transfected with cDNAs encoding a fluorescently labeled transmembrane protein, TGN-38. Under conditions where the transport of this reporter construct was inhibited, the appearance of newly synthesized protein was observed via fluorescent microscopy. The dendritic translation of this protein required activation of glutamate receptors. The results demonstrate a functional capacity for activity-dependent synthesis of integral membrane proteins for distal dendrites in hippocampal neurons. [source] Presynaptic source of quantal size variability at GABAergic synapses in rat hippocampal neurons in cultureEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2004Andrea Barberis Abstract The variability of quantal size depends on both presynaptic (profile of the neurotransmitter concentration in the cleft) and postsynaptic (number and gating properties of postsynaptic receptors) factors. Here we have examined the possibility that at nonsaturated synapses in cultured hippocampal neurons, changes in both the transmitter concentration peak and its clearance from the synaptic cleft may influence the variability of spontaneous miniature synaptic GABAergic currents (mIPSCs). We found that, in contrast to the slow-off GABAA receptor antagonist bicuculline, fast-off competitive antagonists such as SR-95103 and TPMPA differentially blocked small and large mIPSCs. In the presence of flurazepam, a drug believed to increase the affinity of GABA for GABAAR, small mIPSCs were enhanced more efficiently than large events. Moreover, the addition of dextran, which increases the viscosity of the extracellular fluid, preferentially increased small mIPSCs with respect to large ones. These observations suggest that changes in the concentration peak and the speed of GABA clearance in the cleft may be an important source of synaptic variability. The study of the correlation between peak amplitude and kinetics of mIPSCs allowed determination of the relative contribution of transmitter peak concentration vs. time of GABA clearance. Small synaptic responses were associated with fast onset and decay kinetics while large amplitude currents were asociated with slow kinetics, indicating a crucial role for GABA synaptic clearance in variability of mIPSCs. By using model simulations we were able to estimate the range of variability of both the concentration and the speed of clearance of the GABA transient in the synaptic cleft. [source] Saturation and self-inhibition of rat hippocampal GABAA receptors at high GABA concentrationsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2002Katarzyna Mercik Abstract Current responses to ultrafast ,-aminobutyric acid (GABA) applications were recorded from excised patches in rat hippocampal neurons to study the gating properties of GABAA receptors at GABA concentrations close to saturating ones and higher. The amplitude of currents saturated at approximately 1 mm, while the onset rate of responses reached saturation at 4,6 mm GABA. At high GABA concentrations (> 10 mm), the amplitude of current responses was reduced in a dose-dependent manner with a half-blocking GABA concentration of approximately 50 mm. The peak reduction at high GABA doses was accompanied by a tendency to increase the steady-state to peak ratio. At concentrations higher than 30 mm, this effect took the form of a rebound current, i.e. during the prolonged GABA applications, the current firstly declined due to desensitization onset and then, instead of decreasing towards a steady-state value, clearly increased. Both the self-inhibition of GABAA receptors by high GABA doses and rebound were clearly voltage dependent, being larger at positive holding potentials. The fast desensitization component accelerated with depolarization at all saturating [GABA] tested. The rebound phenomenon indicates that the self-block of GABAA receptors is state dependent, and suggests that the sojourn in the desensitized conformation provides a ,rescue' from the block. We propose that high GABA concentrations inhibit the receptors by direct occlusion of the channel pore having no effect on the receptor gating. [source] Changes in the expression of plasma membrane calcium extrusion systems during the maturation of hippocampal neuronsHIPPOCAMPUS, Issue 1 2006Sertac N. Kip Abstract Spatial and temporal control of intracellular calcium signaling is essential for neuronal development and function. The termination of local Ca2+ signaling and the maintenance of basal Ca2+ levels require specific extrusion systems in the plasma membrane. In rat hippocampal neurons (HNs) developing in vitro, transcripts for all isoforms of the plasma membrane Ca2+ pump and the Na/Ca2+ exchanger, and the major nonphotoreceptor Na+/Ca2+,K+ exchangers (NCKX) were strongly upregulated during the second week in culture. Upregulation of plasma membrane calcium ATPases (PMCAs)1, 3, and 4 mRNA coincided with a splice shift from the ubiquitous b-type to the neuron-specific a-type with altered calmodulin regulation. Expression of all PMCA isoforms increased over 5-fold during the first 2 weeks. PMCA immunoreactivity was initially concentrated in the soma and growth cones of developing HNs. As the cells matured, PMCAs concentrated in the dendritic membrane and often colocalized with actin-rich dendritic spines in mature neurons. In the developing rat hippocampal CA1 region, immunohistochemistry confirmed the upregulation of all PMCAs and showed that by the end of the second postnatal week, PMCAs1, 2, and 3 were concentrated in the neuropil, with less intense staining of cell bodies in the pyramidal layer. PMCA4 staining was restricted to a few cells showing intense labeling of the cell periphery and neurites. These results establish that all major Ca2+ extrusion systems are strongly upregulated in HNs during the first 2 weeks of postnatal development. The overall increase in Ca2+ extrusion systems is accompanied by changes in the expression and cellular localization of different isoforms of the Ca2+ pumps and exchangers. The accumulation of PMCAs in dendrites and dendritic spines coincides with the functional maturation in these neurons, suggesting the importance of the proper spatial organization of Ca2+ extrusion systems for synaptic function and development. © 2005 Wiley-Liss, Inc. [source] Calcium/calmodulin-dependent protein kinase type IV is a target gene of the Wnt/,-catenin signaling pathway,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2009Macarena S. Arrázola Calcium/calmodulin-dependent protein kinase IV (CaMKIV) plays a key role in the regulation of calcium-dependent gene expression. The expression of CaMKIV and the activation of CREB regulated genes are involved in memory and neuronal survival. We report here that: (a) a bioinformatic analysis of 15,476 promoters of the human genome predicted several Wnt target genes, being CaMKIV a very interesting candidate; (b) CaMKIV promoter contains TCF/LEF transcription motifs similar to those present in Wnt target genes; (c) biochemical studies indicate that lithium and the canonical ligand Wnt-3a induce CaMKIV mRNA and protein expression levels in rat hippocampal neurons as well as CaMKIV promoter activity; (d) treatment of hippocampal neurons with Wnt-3a increases the binding of ,-catenin to the CaMKIV promoter: (e) In vivo activation of the Wnt signaling improve spatial memory impairment and restores the expression of CaMKIV in a mice double transgenic model for Alzheimer's disease which shows decreased levels of the kinase. We conclude that CaMKIV is regulated by the Wnt signaling pathway and that its expression could play a role in the neuroprotective function of the Wnt signaling against the Alzheimer's amyloid peptide. J. Cell. Physiol. 221: 658,667, 2009. © 2009 Wiley-Liss, Inc. [source] Isoflurane enhances spontaneous Ca2+ oscillations in developing rat hippocampal neurons in vitroACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2009Q. XIANG Background: During the nervous system development, spontaneous synchronized Ca2+ oscillations are thought to possess integrative properties because their amplitude and frequency can influence the patterning of neuronal connection, neuronal differentiation, axon outgrowth, and long-distance wiring. Accumulating studies have confirmed that some drugs such as volatile anesthetic isoflurane produced histopathologic changes in the central nervous system in juvenile animal models. Because the hippocampus plays an important role in learning and memory, the present work was designed to characterize the Ca2+ oscillations regulated by volatile anesthetic isoflurane in primary cultures of developing hippocampal neurons (5-day-cultured). Methods: Primary cultures of rat hippocampal neurons (5-day-cultured) were loaded with the Ca2+ indicator Fluo-4AM (4 ,M) and were studied with a confocal laser microscope. Results: Approximately 22% of 5-day-cultured hippocampal neurons exhibited typical Ca2+ oscillations. These oscillations were dose-dependently enhanced by isoflurane (EC50 0.5 MAC, minimum alveolar concentration) and this effect could be reverted by bicuculline (50 ,M), a specific ,-aminobutyric acid (GABAA) receptor antagonist. Conclusion: Unlike its depressant effect on the Ca2+ oscillations in adult neurons in previous researches, isoflurane dose-dependently enhanced calcium oscillations in developing hippocampal neurons by activating GABAA receptors, a major excitatory receptor in synergy with N -methyl- d -aspartate receptors at the early stages of development. It may be involved in the mechanism of an isoflurane-induced neurotoxic effect in the developing rodent brain. [source] Altered distribution of mitochondria impairs calcium homeostasis in rat hippocampal neurons in cultureJOURNAL OF NEUROCHEMISTRY, Issue 1 2003Guang Jian Wang Abstract The specificity of Ca2+ signals is conferred in part by limiting changes in cytosolic Ca2+ to subcellular domains. Mitochondria play a major role in regulating Ca2+ in neurons and may participate in its spatial localization. We examined the effects of changes in the distribution of mitochondria on NMDA-induced Ca2+ increases. Hippocampal cultures were treated with the microtubule-destabilizing agent vinblastine, which caused the mitochondria to aggregate and migrate towards one side of the neuron. This treatment did not appear to decrease the energy status of mitochondria, as indicated by a normal membrane potential and pH gradient across the inner membrane. Moreover, electron microscopy showed that vinblastine treatment altered the distribution but not the ultrastructure of mitochondria. NMDA (200 µm, 1 min) evoked a greater increase in cytosolic Ca2+ in vinblastine-treated cells than in untreated cells. This increase did not result from impaired Ca2+ efflux, enhanced Ca2+ influx, opening of the mitochondrial permeability transition pore or altered function of endoplasmic reticulum Ca2+ stores. Ca2+ uptake into mitochondria was reduced by 53% in vinblastine-treated cells, as reported by mitochondrially targeted aequorin. Thus, the distribution of mitochondria maintained by microtubules is critical for buffering Ca2+ influx. A subset of mitochondria close to a Ca2+ source may preferentially regulate Ca2+ microdomains, set the threshold for Ca2+ -induced toxicity and participate in local ATP production. [source] Carbohydrate,protein interactions between HNK-1-reactive sulfoglucuronyl glycolipids and the proteoglycan lectin domain mediate neuronal cell adhesion and neurite outgrowthJOURNAL OF NEUROCHEMISTRY, Issue 2 2001Ryu Miura Lecticans, a family of chondroitin sulfate proteoglycans, represent the largest group of proteoglycans expressed in the nervous system. We previously showed that the C-type lectin domains of lecticans bind two classes of sulfated cell surface glycolipids, sulfatides and HNK-1-reactive sulfoglucuronylglycolipids (SGGLs). In this paper, we demonstrate that the interaction between the lectin domain of brevican, a nervous system-specific lectican, and cell surface SGGLs acts as a novel cell recognition system that promotes neuronal adhesion and neurite outgrowth. The Ig chimera of the brevican lectin domain bind to the surface of SGGL-expressing rat hippocampal neurons. The substrate of the brevican chimera promotes adhesion and neurite outgrowth of hippocampal neurons. The authentic, full-length brevican also promotes neuronal cell adhesion and neurite outgrowth. These activities of brevican substrates are neutralized by preincubation of cells with HNK-1 monoclonal antibodies and by pretreatment of the brevican substrates with purified SGGLs. Brevican and HNK-1 carbohydrates are coexpressed in specific layers of the developing hippocampus where axons from entorhinal neurons elongate. Our observations suggest that cell surface SGGLs and extracellular lecticans comprise a novel cell-substrate recognition system operating in the developing nervous system. [source] Glutamate-induced calcium increase mediates magnesium release from mitochondria in rat hippocampal neuronsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 14 2010Yutaka Shindo Abstract Excess administration of glutamate is known to induce Ca2+ overload in neurons, which is the first step in excitotoxicity. Although some reports have suggested a role for Mg2+ in the excitotoxicity, little is known about its actual contribution. To investigate the role of Mg2+ in the excitotoxicity, we simultaneously measured intracellular Ca2+ and Mg2+, using fluorescent dyes, Fura red, a fluorescent Ca2+ probe, and KMG-104, a highly selective fluorescent Mg2+ probe developed by our group, respectively. Administration of 100 ,M glutamate supplemented with 10 ,M glycine to rat hippocampal neurons induced an increase in intracellular Mg2+ concentration ([Mg2+]i). Extracellular Mg2+ was not required for this glutamate-induced increase in [Mg2+]i, and no increase in intracellular Ca2+ concentration ([Ca2+]i) or [Mg2+]i was observed in neurons in nominally Ca2+ -free medium. Application of 5 ,M carbonyl cyanide p -(trifluoromethoxy) phenylhydrazone (FCCP), an uncoupler of mitochondrial inner membrane potential, also elicited increases in [Ca2+]i and [Mg2+]i. Subsequent administration of glutamate and glycine following FCCP treatment did not induce a further increase in [Mg2+]i but did induce an additive increase in [Ca2+]i. Moreover, the glutamate-induced increase in [Mg2+]i was observed only in mitochondria localized areas. These results support the idea that glutamate is able to induced Mg2+ efflux from mitochondria to the cytosol. Furthermore, pretreatment with Ru360, an inhibitor of the mitochondrial Ca2+ uniporter, prevented this [Mg2+]i increase. These results indicate that glutamate-induced increases in [Mg2+]i result from the Mg2+ release from mitochondria and that Ca2+ accumulation in the mitochondria is required for this Mg2+ release. © 2010 Wiley-Liss, Inc. [source] Dock4 regulates dendritic development in hippocampal neuronsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 14 2008Shuhei Ueda Abstract Dendrite development is required for establishing proper neuronal connectivity. Rho-family small GTPases have been reported to play important roles in the regulation of dendritic growth and morphology. However, the molecular mechanisms that control the activities of Rho GTPases in developing dendrites are not well understood. In the present study we found Dock4, an activator of the small GTPase Rac, to have a role in regulating dendritic growth and branching in rat hippocampal neurons. Dock4 is highly expressed in the developing rat brain, predominantly in hippocampal neurons. In dissociated cultured hippocampal neurons, the expression of Dock4 protein is up-regulated after between 3 and 8 days in culture, when dendrites begin to grow. Knockdown of endogenous Dock4 results in reduced dendritic growth and branching. Conversely, overexpression of Dock4 with its binding partner ELMO2 enhances the numbers of dendrites and dendritic branches. These morphological effects elicited by Dock4 and ELMO2 require Rac activation and the C-terminal Crk-binding region of Dock4. Indeed, Dock4 forms a complex with ELMO2 and CrkII in hippocampal neurons. These findings demonstrate a new function of the Rac activator Dock4 in dendritic morphogenesis in hippocampal neurons. © 2008 Wiley-Liss, Inc. [source] Role of kainate receptor activation and desensitization on the [Ca2+]i changes in cultured rat hippocampal neuronsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2001Ana P. Silva Abstract We investigated the role of kainate (KA) receptor activation and desensitization in inducing the increase in the intracellular free Ca2+ concentration ([Ca2+]i) in individual cultured rat hippocampal neurons. The rat hippocampal neurons in the cultures were shown to express kainate receptor subunits, KA2 and GluR6/7, either by immunocytochemistry or by immunoblot analysis. The effect of LY303070, an ,-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA) receptor antagonist, on the alterations in the [Ca2+]i caused by kainate showed cell-to-cell variability. The [Ca2+]i increase caused by kainate was mostly mediated by the activation of AMPA receptors because LY303070 inhibited the response to kainate in a high percentage of neurons. The response to kainate was potentiated by concanavalin A (Con A), which inhibits kainate receptor desensitization, in 82.1% of the neurons, and this potentiation was not reversed by LY303070 in about 38% of the neurons. Also, upon stimulation of the cells with 4-methylglutamate (MGA), a selective kainate receptor agonist, in the presence of Con A, it was possible to observe [Ca2+]i changes induced by kainate receptor activation, because LY303070 did not inhibit the response in all neurons analyzed. In toxicity studies, cultured rat hippocampal neurons were exposed to the drugs for 30 min, and the cell viability was evaluated at 24 hr using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The selective activation of kainate receptors with MGA, in the presence of Con A, induced a toxic effect, which was not prevented by LY303070, revealing a contribution of a small subpopulation of neurons expressing kainate receptors that independently mediate cytotoxicity. Taken together, these results indicate that cultured hippocampal neurons express not only AMPA receptors, but also kainate receptors, which can modulate the [Ca2+]i and toxicity. J. Neurosci. Res. 65:378,386, 2001. © 2001 Wiley-Liss, Inc. [source] AMPA receptor antibodies in limbic encephalitis alter synaptic receptor location,ANNALS OF NEUROLOGY, Issue 4 2009Meizan Lai MD Objective To report the clinical and immunological features of a novel autoantigen related to limbic encephalitis (LE) and the effect of patients' antibodies on neuronal cultures. Methods We conducted clinical analyses of 10 patients with LE. Immunoprecipitation and mass spectrometry were used to identify the antigens. Human embryonic kidney 293 cells expressing the antigens were used in immunocytochemistry and enzyme-linked immunoabsorption assay. The effect of patients' antibodies on cultures of live rat hippocampal neurons was determined with confocal microscopy. Results Median age was 60 (38,87) years; 9 were women. Seven had tumors of the lung, breast, or thymus. Nine patients responded to immunotherapy or oncological therapy, but neurological relapses, without tumor recurrence, were frequent and influenced the long-term outcome. One untreated patient died of LE. All patients had antibodies against neuronal cell surface antigens that by immunoprecipitation were found to be the glutamate receptor 1 (GluR1) and GluR2 subunits of the ,-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR). Human embryonic kidney 293 cells expressing GluR1/2 reacted with all patients' sera or cerebrospinal fluid, providing a diagnostic test for the disorder. Application of antibodies to cultures of neurons significantly decreased the number of GluR2-containing AMPAR clusters at synapses with a smaller decrease in overall AMPAR cluster density; these effects were reversed after antibody removal. Interpretation Antibodies to GluR1/2 associate with LE that is often paraneoplastic, treatment responsive, and has a tendency to relapse. Our findings support an antibody-mediated pathogenesis in which patients' antibodies alter the synaptic localization and number of AMPARs. Ann Neurol 2009;65:424,434 [source] Bicuculline, pentobarbital and diazepam modulate spontaneous GABAA channels in rat hippocampal neuronsBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2000Bryndis Birnir Spontaneously opening, chloride-selective channels that showed outward rectification were recorded in ripped-off patches from rat cultured hippocampal neurons and in cell-attached patches from rat hippocampal CA1 pyramidal neurons in slices. In both preparations, channels had multiple conductance states and the most common single-channel conductance varied. In the outside-out patches it ranged from 12 to 70 pS (Vp=40 mV) whereas in the cell-attached patches it ranged from 56 to 85 pS (,Vp=80 mV). Application of GABA to a patch showing spontaneous channel activity evoked a rapid, synchronous activation of channels. During prolonged exposure to either 5 or 100 ,M GABA, the open probability of channels decreased. Application of GABA appeared to have no immediate effect on single-channel conductance. Exposure of the patches to 100 ,M bicuculline caused a gradual decrease on the single-channel conductance of the spontaneous channels. The time for complete inhibition to take place was slower in the outside-out than in the cell-attached patches. Application of 100 ,M pentobarbital or 1 ,M diazepam caused 2,4 fold increase in the maximum channel conductance of low conductance (<40 pS) spontaneously active channels. The observation of spontaneously opening GABAA channels in cell-attached patches on neurons in slices suggests that they may have a role in neurons in vivo and could be an important site of action for some drugs such as benzodiazepines, barbiturates and general anaesthetics. British Journal of Pharmacology (2000) 131, 695,704; doi:10.1038/sj.bjp.0703621 [source] | ||||||||||||||||