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The article presents abstracts of research papers related to cell lineage and differentiation. They include "A novel role of carnitine derivatives in the nervous system," "Neurons differentiated from embryonic stem cells migrate along both glial and neuronal processes in vitro," and "The Alzheimer-related gene presenilin-1 facilitates sonic hedgehog signaling in Xenopus primary neurogenesis."

The article presents information on an abstract of the paper "In Vitro Myelination in Co-Cultures of Postnatal Rat Drg Neurons And Oligodendrocytes," which will be presented at the 30th meeting of the American Society for Neurochemistry. The meeting will be held in New Orleans, Louisiana, from March 14-17, 1999. The paper findings highlight that both oligodendrocytes and neurons survive longer when cultured together.

Amyloid beta (Aβ) peptide is the major constituent of the extracellular amyloid plaques deposited in the brains of Alzheimer's disease patients and is central to the pathogenic pathway causing this disease. The identity of the neurotoxic Aβ species remains elusive. We previously reported that Aβ toxicity correlates strongly with its neuronal cell binding leading us to hypothesize that neuronal cell death is caused by the binding of a specific oligomeric Aβ species. To identify the specific oligomeric Aβ species that is associated with cell death, we treated mouse cortical neuronal cultures with synthetic Aβ40 and Aβ42 peptides and identified that the cellular Aβ binding and neurotoxicity were time and concentration dependent. We found a significant correlation between the amount of trimer and tetramer species bound to neurons with increasing neurotoxicity. We prepared Aβ40 oligomers (up to tetramers) using photo-induced cross-linking of unmodified peptides to confirm this oligomer-specific neurotoxic activity. Our results identify the Aβ tetramer, followed by the trimer, as the most toxic low-order oligomers Aβ species. [ABSTRACT FROM AUTHOR]

Presents abstracts of papers featured in the "Journal of Neurochemistry" that deal with dietary and aging influences on neuronal function. "Slowing brain aging by calorie restriction and calorie restriction mimetics"; "Behavioral and neuronal effects of fruit polyphenolics"; "Molecular inflammation hypothesis of aging based on the anti-aging mechanism of calorie restriction".

J. Neurochem. (2012) 121, 561-574. Abstract Neuroserpin is a brain-specific serine protease inhibitor that is expressed in the developing and adult nervous system. Its expression profile led to suggestions that it played roles in neuronal growth and connectivity. In this study, we provide direct evidence to support a role for neuroserpin in axon and dendritic growth. We report that axon growth is enhanced while axon and dendrite diameter are reduced following neuroserpin treatment of hippocampal neurons. More complex effects are seen on dendritic growth and branching with neuroserpin-stimulating dendritic growth and branching in young neurons but switching to an inhibitory response in older neurons. The protease inhibitory activity of neuroserpin is not required to activate changes in neuronal morphology and a proportion of responses are modulated by an antagonist to the LRP1 receptor. Collectively, these findings support a key role for neuroserpin as a regulator of neuronal development through a non-inhibitory mechanism and suggest a basis for neuroserpin's effects on complex emotional behaviours and recent link to schizophrenia. [ABSTRACT FROM AUTHOR]

J. Neurochem. (2012) 121, 587-596. Abstract Changes in the density of NMDA (GluN) receptors in the neuronal membrane are critical for plasticity, whereas malfunction of precisely regulated GluN receptor activity may be involved in neurotoxicity. In cultured rat neocortical interneurons, we have studied the regulation of the surface density of GluN1, GluN2A and GluN2B subunits. Application of 5 μMol NMDA for 24 h followed by a washout period of 24 h decreased the response of GluN receptors for at least 2 days. The reduction was caused by a decrease in the surface density of GluN1/GluN2B subunits, whereas GluN2A subunits remained unaffected. Our data indicate that long but reversible low level activation of GluN receptors can cause long-term changes in their subunit composition in cultured interneurons. [ABSTRACT FROM AUTHOR]

In vertebrates, a brain-specific transcript from the atypical protein kinase C (PKC) ζ gene encodes protein kinase M (PKM) ζ, a constitutively active kinase implicated in the maintenance of synaptic plasticity and memory. We have cloned the atypical PKC from Aplysia, PKC Apl III. We did not find a transcript in Aplysia encoding PKMζ, and evolutionary analysis of atypical PKCs suggests formation of this transcript is restricted to vertebrates. Instead, over-expression of PKC Apl III in Aplysia sensory neurons leads to production of a PKM fragment of PKC Apl III. This cleavage was induced by calcium and blocked by calpain inhibitors. Moreover, nervous system enriched spliced forms of PKC Apl III show enhanced cleavage. PKC Apl III could also be activated through phosphorylation downstream of phosphoinositide 3-kinase. We suggest that PKM forms of atypical PKCs play a conserved role in memory formation, but the mechanism of formation of these kinases has changed over evolution. [ABSTRACT FROM AUTHOR]

Although the potential of adult neural stem cells to repair damage via cell replacement has been widely reported, the ability of endogenous stem cells to positively modulate damage is less well studied. We investigated whether medium conditioned by adult hippocampal stem/progenitor cells altered the extent of excitotoxic cell death in hippocampal slice cultures. Conditioned medium significantly reduced cell death following 24 h of exposure to 10 μM NMDA. Neuroprotection was greater in the dentate gyrus, a region neighboring the subgranular zone where stem/progenitor cells reside compared with pyramidal cells of the cornis ammonis. Using mass spectrometric analysis of the conditioned medium, we identified a pentameric peptide fragment that corresponded to residues 26–30 of the insulin B chain which we termed ‘pentinin’. The peptide is a putative breakdown product of insulin, a constituent of the culture medium, and may be produced by insulin-degrading enzyme, an enzyme expressed by the stem/progenitor cells. In the presence of 100 pM of synthetic pentinin, the number of mature and immature neurons killed by NMDA-induced toxicity was significantly reduced in the dentate gyrus. These data suggest that progenitors in the subgranular zone may convert exogenous insulin into a peptide capable of protecting neighboring neurons from excitotoxic injury. [ABSTRACT FROM AUTHOR]

In order to determine the sequence of cellular processes in glutamate toxicity, we simultaneously recorded O2 consumption, cytosolic Ca2+ concentration ([Ca2+]i), and mitochondrial membrane potential (mΔψ) in single cortical neurons. Oxygen consumption was measured using an amperometric self-referencing platinum electrode adjacent to neurons in which [Ca2+]i and mΔψ were monitored with Fluo-4 and TMRE+, respectively, using a spinning disk laser confocal microscope. Excitotoxic doses of glutamate caused an elevation of [Ca2+]i followed seconds afterwards by an increase in O2 consumption which reached a maximum level within 1–5 min. A modest increase in mΔψ occurred during this time period, and then, shortly before maximal O2 consumption was reached, the mΔψ, as indicated by TMRE+ fluorescence, dissipated. Maximal O2 consumption lasted up to 5 min and then declined together with mΔψ and ATP levels, while [Ca2+]i further increased. mΔψ and [Ca2+]i returned to baseline levels when neurons were treated with an NMDA receptor antagonist shortly after the [Ca2+]i increased. Our unprecedented spatial and time resolution revealed that this sequence of events is identical in all neurons, albeit with considerable variability in magnitude and kinetics of changes in O2 consumption, [Ca2+]i, and mΔψ. The data obtained using this new method are consistent with a model where Ca2+ influx causes ATP depletion, despite maximal mitochondrial respiration, minutes after glutamate receptor activation. [ABSTRACT FROM AUTHOR]

5-hydroxytryptamine (5-HT) or serotonin 2A receptors play an important role in modulation of prefrontal cortex (PFC) activity and have been implicated in the physiopathology of psychiatric disorders. There is no quantitative information on the percentage of glutamatergic and GABAergic cells that express 5-HT2A receptors in human and monkey PFC. We have used double in situ hybridization to quantify the mRNA co-localization of 5-HT2A receptor with the glutamatergic transporter vesicular glutamate transporter 1, and with the GABAergic marker glutamic acid decarboxylase 65/67 and in parvalbumin and calbindin GABAergic cell populations. Our results show that nearly every glutamatergic cell (86–100%) in layers II-V expressed 5-HT2A receptor mRNA in both species. This percentage was lower in layer VI (13–31%). In contrast, not all the GABAergic interneurons (13–46%) expressed 5-HT2A receptor mRNA. This receptor was expressed in 45–69% of parvalbumin and in 61–87% of calbindin positive cells. These results indicate that, while the majority of glutamatergic neurons can be sensitive to 5-HT action via 5-HT2A receptors, this modulation occurs only in a limited population of GABAergic interneurons and provides new neuroanatomical information about the role played by serotonin through 5-HT2A receptors in the PFC and on the sites of action for drugs such as antipsychotics and antidepressants used in treatment of psychiatric disorders. [ABSTRACT FROM AUTHOR]

Recent studies showed that endocytosis is enhanced in neurons exposed to an excitototoxic stimulus. We here confirm and analyze this new phenomenon using dissociated cortical neuronal cultures. NMDA-induced uptake (FITC-dextran or FITC or horseradish peroxidase) occurs in these cultures and is due to endocytosis, not to cell entry through damaged membranes; it requires an excitotoxic dose of NMDA and is dependent on extracellular calcium, but occurs early, while the neuron is still intact and viable. It involves two components, NMDA-induced and constitutive, with different characteristics. Neither component involves specific binding of the endocytosed molecules to a saturable receptor. Strikingly, molecules internalized by the NMDA-induced component are targeted to neuronal nuclei. This component, but not the constitutive one, is blocked by a c- Jun N-terminal protein kinase inhibitor. In conclusion, an excitotoxic dose of NMDA triggers c- Jun N-terminal protein kinase-dependent endocytosis in cortical neuronal cultures, providing an in vitro model of the excitotoxicity-induced endocytosis reported in intact tissues. [ABSTRACT FROM AUTHOR]

Synaptic transmission depends on the regulated surface expression of neurotransmitter receptors, but many of the cellular processes required to achieve this remain poorly understood. To better define specific mechanisms for the GABAB receptor (GABABR) trafficking, we screened for proteins that bind to the carboxy-terminus of the GABAB1 subunit. We report the identification and characterization of a novel 130-kDa protein, GPCR interacting scaffolding protein (GISP), that interacts directly with the GABAB1 subunit via a coiled-coil domain. GISP co-fractionates with GABABR and with the postsynaptic density and co-immunoprecipitates with GABAB1 and GABAB2 from rat brain. In cultured hippocampal neurons, GISP displays a punctate dendritic distribution and has an overlapping localization with GABABRs. When co-expressed with GABABRs in human embryonic kidney cells, GISP promotes GABABR surface expression and enhances both baclofen-evoked extracellular signal-regulated kinase (ERK) phosphorylation and G-protein inwardly rectifying potassium channel (GIRK) currents. These results suggest that GISP is involved in the forward trafficking and stabilization of functional GABABRs. [ABSTRACT FROM AUTHOR]

Glycerotoxin (GLTx) is capable of stimulating neurotransmitter release at the frog neuromuscular junction by directly interacting with N-type Ca2+ (Cav2.2) channels. Here we have utilized GLTx as a tool to investigate the functionality of Cav2.2 channels in various mammalian neuronal preparations. We first adapted a fluorescent-based high-throughput assay to monitor glutamate release from rat cortical synaptosomes. GLTx potently stimulates glutamate secretion and Ca2+ influx in synaptosomes with an EC50 of 50 pm. Both these effects were prevented using selective Cav2.2 channel blockers suggesting the functional involvement of Cav2.2 channels in mediating glutamate release in this system. We further show that both Cav2.1 (P/Q-type) and Cav2.2 channels contribute equally to depolarization-induced glutamate release. We then investigated the functionality of Cav2.2 channels at the neonatal rat neuromuscular junction. GLTx enhances both spontaneous and evoked neurotransmitter release causing a significant increase in the frequency of postsynaptic action potentials. These effects were blocked by specific Cav2.2 channel blockers demonstrating that either GLTx or its derivatives could be used to selectively enhance the neurotransmitter release from Cav2.2-expressing mammalian neurons. [ABSTRACT FROM AUTHOR]

To identify the intracellular signaling pathways that mediate the pro-survival activity of NMDA receptors (NMDARs), we studied effects of exogenous NMDA on cultured rat cortical and hippocampal neurons that were treated with a phosphatidylinositol-3-kinase (PI3K) inhibitor, LY294002. NMDA at 5 or 10 µm protected against LY294002-induced apoptosis, suggesting NMDAR-mediated activation of a survival signaling pathway that is PI3K-independent. NR2B-specific NMDAR blockers antagonized anti-apoptotic effects of NMDA, indicating a critical role of NR2B NMDARs in the neuroprotection. NMDA at 10 µm suppressed LY294002-induced activation of a pro-apoptotic kinase, glycogen synthase kinase 3β (GSK3β). GSK3β activation by LY294002 was associated with decreased levels of inhibitory GSK3β phosphorylation at the Ser9 residue. However, NMDA did not prevent the LY294002-mediated decline of phospho-Ser9 levels. In addition, NMDA inhibited cortical neuron apoptosis induced by the overexpression of either wild type (wt) or Ser9Ala mutant form of GSK3β, suggesting that NMDA suppressed GSK3β in a Ser9-independent manner. Finally, inhibition of NR2B NMDARs reduced the NMDA protection against overexpression of GSK3βwt. These data indicate that moderate stimulation of NR2B NMDAR protects against inhibition of PI3K by a Ser9-independent inhibition of the pro-apoptotic activity of GSK3β. Hence, the activation of NR2B and the Ser9-independent inhibition of GSK3β are two newly identified elements of the signaling network that mediates the pro-survival effects of NMDA. [ABSTRACT FROM AUTHOR]

The article presents abstracts of papers related to pain. They include "P2Y receptor-mediated calcium signaling in capsaicin-sensitive dorsal root ganglion neurons," "Neuropeptide Y and Y1 receptor like immunoreactivity in dorsal root ganglia and spinal cord after colchicine application to the sciatic nerve in the rat," and "Elevation of S-100b level in rat brain and blood serum under postoperative pain."

The specific roles of syntaxin 5 (Syx 5) in the interaction with presenilin (PS) and the accumulation of β-amyloid precursor protein (βAPP), as well as the secretion of β-amyloid peptide (Aβ peptide) were examined in NG108-15 cells. Syx 5, which localizes from the endoplasmic reticulum (ER) to the Golgi, bound to PS holoproteins, while the other Syxs studied did not. Among familial Alzheimer's disease (FAD)-linked PS mutants, PS1ΔE9, which lacks the endoproteolytic cleavage site, showed markedly decreased binding to Syx 5. The interaction domains in Syx 5 were mapped to the transmembrane region and to the cytoplasmic region containing the α-helical domains, which are distinct from the H3 (SNARE motif). Among all of the Syxs examined, only overexpression of Syx 5 resulted in the accumulation of βAPP in the ER to cis-Golgi compartment, an attenuation of the amount of the C-terminal fragment (APP-CTF) of βAPP, and a reduction in the secretion of Aβ peptides. Furthermore, co-expression of Syx 5 with C99 resulted in an increase in APP-CTF and suppressed Aβ secretion. Taken together, these results indicate that Syx 5 may play a specific role in the modulation of processing and/or trafficking of FAD-related proteins in neuronal cells by interaction with PS holoproteins in the early secretory compartment of neuronal cells. [ABSTRACT FROM AUTHOR]

NMDA receptors are involved in a variety of brainstem functions. The excitatory postsynaptic NMDA currents of pre-Bötzinger complex interneurons and hypoglossal motoneurons, which are located in the medulla oblongata, show remarkably fast deactivation kinetics of approximately 30 ms compared with NMDA receptors in other types of neurons. Because structural heterogeneity might be the basis for physiological properties, we examined the expression of six NMDA receptor subunits (NMDAR1, NR2A−2D, and NR3A) plus eight NMDR1 splice variants in pre-Bötzinger complex, hypoglossal and, for comparison, neurons from the nucleus of the solitary tract in young rats using single cell multiplex RT–PCR. Expression of NR2A, NR2B, and NR2D was observed in all three cell types while NR3A was much more abundant in pre-Bötzinger complex interneurons, which belong to the rhythm generator of respiratory activity. In hypoglossal neurons, the NMDAR1 splice variants NMDAR1–4a and NMDAR1–4b were found. In neurons of the nucleus of the solitary tract, instead of NMDAR1–4b, the NMDAR1–2a splice variant was detected. This differential expression of modulatory splice variants might be the molecular basis for the characteristic functional properties of NMDA receptors, as neurons expressing a special NMDAR1 splice variant at the mRNA level show fast kinetics compared with neurons lacking this splice variant. [ABSTRACT FROM AUTHOR]

The effects of nine polyphenolic compounds on glutamate-mediated toxicity were investigated. The underlying mechanisms by which a polyphenolic compound confers its effect were also elucidated. Treatment of cortical neurons with 50 µmglutamate for 24 h decreased cell viability by 45.8 ± 7.9%, and 50 µmof tournefolic acid B methyl ester attenuated glutamate-induced cell death by 46.8 ± 17.8%. Glutamate increased the activity of caspase 35.2-fold, and to a similar extent for caspase 2, 6, 8 and 9. Tournefolic acid B methyl ester abrogated glutamate-induced activation of caspase 2, 3, 6 and 9 by about 70%, and to a lesser extent for caspase 8. Treatment with glutamate for 1 h elevated reactive oxygen species (ROS) by 208.3 ± 21.3%. Tournefolic acid B methyl ester eliminated the glutamate-induced accumulation of ROS. Glutamate increased the phosphorylation of p54-c-jun N-terminal kinase (JNK) concomitantly with activation of the endogenous antioxidant defense system. Tournefolic acid B methyl ester at 50 µmdiminished the activity of p54-JNK in control and glutamate-treated cells, coinciding with theabolishment of the glutamate-triggered antioxidant defense system. Therefore, tournefolic acid B methyl ester blocked the activation of the caspase cascade, eliminated ROS accumulation and abrogated the activation of JNK, thereby conferring a neuroprotective effect on glutamate-mediated neurotoxicity. [ABSTRACT FROM AUTHOR]

The environmental context in which psychostimulant drugs are experienced influences their ability to induce immediate early genes (lEGs) in the striatum. When given in the home cage amphetamine induces lEGs predominately in striatonigral neurons, but when given in a novel test environment amphetamine also induces lEGs in striatopallidal neurons. The source of the striatopetal projections that regulate the ability of amphetamine to differentially engage these two striatofugal circuits has never been described. We report that transection of corticostriatal afferents selectively blocks, whereas enhancement of cortical activity with an ampakine selectively augments, the number of amphetamine-evoked c-fos-positive striatopallidal (but not striatonigral) neurons. In addition, blockade of the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) signaling cascade preferentially inhibits the number of amphetamine-evoked c-fos-positive striatopallidal neurons. These results suggest that glutamate released from corticostriatal afferents modulates the ability of amphetamine to engage striatopallidal neurons through an ERK/MAPK signaling-dependent mechanism. We speculate that this may be one mechanism by which environmental context facilitates some forms of drug experience-dependent plasticity, such as psychomotor sensitization. [ABSTRACT FROM AUTHOR]

Arc is an effector immediate early gene whose expression is induced in situations of increased neuronal activity. However, there is no report on the influence of stress on Arc expression. Here, we compared the induction of both c-fos and Arc mRNAs in the brain of rats exposed to one of three different stressful situations: novel environment, forced swimming and immobilization. An absent or weak c-fos mRNA signal was observed in control rats, whereas those exposed to one of three stressors showed enhanced c-fos expression in a wide range of brain areas. Constitutive Arc expression was observed in some areas such as cortex, striatum, hippocampus, reticular thalamic nucleus and cerebellar cortex. In response to stressors, a strong induction of Arc was observed, but the pattern was different from that of c-fos. For instance, activation of Arc but not c-fos was observed in the nucleus accumbens after immobilization and in the hippocampus after novel environment. No Arc induction was observed in diencephalic and brainstem areas. The present data show that Arc has a neuroanatomically restricted pattern of induction in the brain after emotional stress. Telencephalic activation suggests that a more intense induction of synaptic plasticity is occurring in this area after exposure to emotional stressors. [ABSTRACT FROM AUTHOR]

All tissues contain the enzymes that modify and remove O-GIcNAc dynamically from nucleocytoplasmic proteins. These enzymes have been shown to play a role in the control of transcription, vesicular trafficking and, more recently, proteasome function. Modification by O-GIcNAc of the 19S cap of the proteasome inhibits proteasomal function. Transcripts of both O-GIcNAc transferase and O-GlcNAcase are very abundant in the brain, with the highest concentrations in hippocampal neurons and Purkinje cells. When the on-rate of modification is favored over the off-rate by intraventricular administration of a drug, streptozocin, these areas of the brain display the most rapid accumulation of O-GIcNAc. Cerebral proteasome function is reduced and ubiquitin and p53 accumulate in these brain regions, with the subsequent activation of a p53-dependent transgene and the endogenous Mdm2 gene. Later, some hippocampal cells, but not Purkinje cells, undergo apoptosis. These observations suggest that the O- GlcNAc system may participate in neurodegeneration, particularly in the hippocampus. [ABSTRACT FROM AUTHOR]

Childhood-onset dystonia is an autosomal dominant movement disorder associated with a three base pair (GAG) deletion mutation in the DYT1 gene. This gene encodes a novel ATP-binding protein called torsinA, which in the central nervous system is expressed exclusively in neurons. Neither the function of torsinA nor its role in the pathophysiology of DYT1 dystonia is known. In order to better understand the cellular functions of torsinA, we established PC12 cell lines overexpressing wild-type or mutant torsinA and subjected them to various conditions deleterious to cell survival. Treatment of control PC12 cells with an inhibitor of proteasomal activity, an oxidizing agent, or trophic withdrawal, resulted in cell death, whereas PC12 cells that overexpressed torsinA were significantly protected against each of these treatments. Overexpression of mutant torsinA failed to protect cells against trophic withdrawal. These results suggest that torsinA may play a protective role in neurons against a variety of cellular insults. [ABSTRACT FROM AUTHOR]

The article presents an abstract of the research paper "Immunocytochemical Localization of ß-Methylcrotonyl-Coa Carboxylase in Astroglial Cells and Neurons in Culture." It will be presented in the joint meeting of the International Society for Neurochemistry and the European Society of Neurochemistry that will be held in Berlin, Germany from August 8-14, 1999. Branched-chain amino acids particularly leucine were metabolized as energy substrates.

The article presents an abstract of the study "Neurotrophin Signal Transduction in the Survival of Neurons and Neural Tumor Cells." The study reports on how multiple signaling proteins and pathways contribute to the elaboration of the neuronal phenotype. The research paper for the study would be presented in the 30th Annual Meeting of the American Society for Neurochemistry, on March 14-17, 1999, in New Orleans, Louisiana.

The article presents an abstract of the study "Cocaine Inhibition of Neuronal Differentiation in NGF-Induced PC12 Cells is Independent of RAS Signaling." The study reports that, cocaine and dopamine affect the NGF signaling downstream or independent of Ras. The research paper for the study would be presented in the 30th Annual Meeting of the American Society for Neurochemistry, on March 14-17, 1999, in New Orleans, Louisiana.

The article presents an abstract of the study "Expression of Neuregulin 1 Isoforms and Receptors in E18 Rat Basal Forebrain Neuron-Enriched Cultures." The study reports that, embryonic basal forebrain neurons may be a source of multiple Neuregulin 1 isoforms that can produce diverse neurotrophic and gliotrophic effects. The research paper for the study would be presented in the 30th Annual Meeting of the American Society for Neurochemistry, on March 14-17, 1999, in New Orleans, Louisiana.

The article presents an abstract of the study "Target Tissues Influence Dendritic Growth in Sympathetic Neurons via Osteogenic Protein-1." The study reported that dendritic growth in cultured sympathetic neuronal cell type may be regulated through retrograde interactions with target-derived osteogenic protein-1. The research paper for the study would be presented in the 30th Annual Meeting of the American Society for Neurochemistry, on March 14-17, 1999, in New Orleans, Louisiana.

The author reflects on the study conducted by E. S. Lippmann and colleagues on the blood-brain barrier (BBB) modeling. The author states that the study is important, considering the difficulties in getting human neurons and astrocytes for the in vitro modeling of BBB. Meanwhile, author mentions that in vitro BBB models have become increasingly hard to analyze the interactions of neurovascular unit's various cell types.