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Sample records for neurotransmitter transporters focus

  1. Cytoplasmic permeation pathway of neurotransmitter transporters.

    PubMed

    Rudnick, Gary

    2011-09-06

    Ion-coupled solute transporters are responsible for transporting nutrients, ions, and signaling molecules across a variety of biological membranes. Recent high-resolution crystal structures of several transporters from protein families that were previously thought to be unrelated show common structural features indicating a large structural family representing transporters from all kingdoms of life. This review describes studies that led to an understanding of the conformational changes required for solute transport in this family. The first structure in this family showed the bacterial amino acid transporter LeuT, which is homologous to neurotransmitter transporters, in an extracellularly oriented conformation with a molecule of leucine occluded at the substrate site. Studies with the mammalian serotonin transporter identified positions, buried in the LeuT structure, that defined a potential pathway leading from the cytoplasm to the substrate binding site. Modeling studies utilized an inverted structural repeat within the LeuT crystal structure to predict the conformation of LeuT in which the cytoplasmic permeation pathway, consisting of positions identified in SERT, was open for diffusion of the substrate to the cytoplasm. From the difference between the model and the crystal structures, a simple "rocking bundle" mechanism was proposed, in which a four-helix bundle changed its orientation with respect to the rest of the protein to close the extracellular pathway and open the cytoplasmic one. Subsequent crystal structures from structurally related proteins provide evidence supporting this model for transport.

  2. Neurotransmitters

    NASA Video Gallery

    Our nerve cells (neurons) communicate with each other using little chemical messengers called neurotransmitters. These neurotransmitters are transferred from one neuron to the next within a space c...

  3. Mechanism for alternating access in neurotransmitter transporters.

    PubMed

    Forrest, Lucy R; Zhang, Yuan-Wei; Jacobs, Miriam T; Gesmonde, Joan; Xie, Li; Honig, Barry H; Rudnick, Gary

    2008-07-29

    Crystal structures of LeuT, a bacterial homologue of mammalian neurotransmitter transporters, show a molecule of bound substrate that is essentially exposed to the extracellular space but occluded from the cytoplasm. Thus, there must exist an alternate conformation for LeuT in which the substrate is accessible to the cytoplasm and a corresponding mechanism that switches accessibility from one side of the membrane to the other. Here, we identify the cytoplasmic accessibility pathway of the alternate conformation in a mammalian serotonin transporter (SERT) (a member of the same transporter family as LeuT). We also propose a model for the cytoplasmic-facing state that exploits the internal pseudosymmetry observed in the crystal structure. LeuT contains two structurally similar repeats (TMs1-5 and TMs 6-10) that are inverted with respect to the plane of the membrane. The conformational differences between them result in the formation of the extracellular pathway. Our model for the cytoplasm-facing state exchanges the conformations of the two repeats and thus exposes the substrate and ion-binding sites to the cytoplasm. The conformational change that connects the two states primarily involves the tilting of a 4-helix bundle composed of transmembrane helices 1, 2, 6, and 7. Switching the tilt angle of this bundle is essentially equivalent to switching the conformation of the two repeats. Extensive mutagenesis of SERT and accessibility measurements, using cysteine reagents, are accommodated by our model. These observations may be of relevance to other transporter families, many of which contain internal inverted repeats.

  4. Are vesicular neurotransmitter transporters potential treatment targets for temporal lobe epilepsy?

    PubMed Central

    Van Liefferinge, Joeri; Massie, Ann; Portelli, Jeanelle; Di Giovanni, Giuseppe; Smolders, Ilse

    2013-01-01

    The vesicular neurotransmitter transporters (VNTs) are small proteins responsible for packing synaptic vesicles with neurotransmitters thereby determining the amount of neurotransmitter released per vesicle through fusion in both neurons and glial cells. Each transporter subtype was classically seen as a specific neuronal marker of the respective nerve cells containing that particular neurotransmitter or structurally related neurotransmitters. More recently, however, it has become apparent that common neurotransmitters can also act as co-transmitters, adding complexity to neurotransmitter release and suggesting intriguing roles for VNTs therein. We will first describe the current knowledge on vesicular glutamate transporters (VGLUT1/2/3), the vesicular excitatory amino acid transporter (VEAT), the vesicular nucleotide transporter (VNUT), vesicular monoamine transporters (VMAT1/2), the vesicular acetylcholine transporter (VAChT) and the vesicular γ-aminobutyric acid (GABA) transporter (VGAT) in the brain. We will focus on evidence regarding transgenic mice with disruptions in VNTs in different models of seizures and epilepsy. We will also describe the known alterations and reorganizations in the expression levels of these VNTs in rodent models for temporal lobe epilepsy (TLE) and in human tissue resected for epilepsy surgery. Finally, we will discuss perspectives on opportunities and challenges for VNTs as targets for possible future epilepsy therapies. PMID:24009559

  5. Bound to be different: neurotransmitter transporters meet their bacterial cousins.

    PubMed

    Henry, L Keith; Meiler, Jens; Blakely, Randy D

    2007-12-01

    The neurotransmitter transporters belonging to the solute carrier 6 (SLC6) family, including the gamma-aminobutyric acid (GAT), norepinephrine (NET), serotonin (SERT) and dopamine (DAT) transporters are extremely important drug targets of great clinical relevance. These Na+, Cl(-)-dependent transporters primarily function following neurotransmission to reset neuronal signaling by transporting neurotransmitter out of the synapse and back into the pre-synaptic neuron. Recent studies have tracked down an elusive binding site for Cl(-) that facilitates neurotransmitter transport using structural differences evident with bacterial family members (e.g., the Aquifex aeolicus leucine transporter LeuT Aa) that lack Cl(-) dependence. Additionally, the crystal structures of antidepressant-bound LeuT Aa reveals a surprising mode of drug interaction that may have relevance for medication development. The study of sequence and structural divergence between LeuT Aa and human SLC6 family transporters can thus inform us as to how and why neurotransmitter transporters evolved a reliance on extracellular Cl(-) to propel the transport cycle; what residue changes and helical rearrangements give rise to recognition of different substrates; and how drugs such as antidepressants, cocaine, and amphetamines halt (or reverse) the transport process.

  6. A neurotransmitter transporter encoded by the Drosophila inebriated gene

    PubMed Central

    Soehnge, Holly; Huang, Xi; Becker, Marie; Whitley, Penn; Conover, Diana; Stern, Michael

    1996-01-01

    Behavioral and electrophysiological studies on mutants defective in the Drosophila inebriated (ine) gene demonstrated increased excitability of the motor neuron. In this paper, we describe the cloning and sequence analysis of ine. Mutations in ine were localized on cloned DNA by restriction mapping and restriction fragment length polymorphism (RFLP) mapping of ine mutants. DNA from the ine region was then used to isolate an ine cDNA. In situ hybridization of ine transcripts to developing embryos revealed expression of this gene in several cell types, including the posterior hindgut, Malpighian tubules, anal plate, garland cells, and a subset of cells in the central nervous system. The ine cDNA contains an open reading frame of 658 amino acids with a high degree of sequence similarity to members of the Na+/Cl−-dependent neurotransmitter transporter family. Members of this family catalyze the rapid reuptake of neurotransmitters released into the synapse and thereby play key roles in controlling neuronal function. We conclude that ine mutations cause increased excitability of the Drosophila motor neuron by causing the defective reuptake of the substrate neurotransmitter of the ine transporter and thus overstimulation of the motor neuron by this neurotransmitter. From this observation comes a unique opportunity to perform a genetic dissection of the regulation of excitability of the Drosophila motor neuron. PMID:8917579

  7. How LeuT shapes our understanding of the mechanisms of sodium-coupled neurotransmitter transporters.

    PubMed

    Penmatsa, Aravind; Gouaux, Eric

    2014-03-01

    Neurotransmitter transporters are ion-coupled symporters that drive the uptake of neurotransmitters from neural synapses. In the past decade, the structure of a bacterial amino acid transporter, leucine transporter (LeuT), has given valuable insights into the understanding of architecture and mechanism of mammalian neurotransmitter transporters. Different conformations of LeuT, including a substrate-free state, inward-open state, and competitive and non-competitive inhibitor-bound states, have revealed a mechanistic framework for the transport and transport inhibition of neurotransmitters. The current review integrates our understanding of the mechanistic and pharmacological properties of eukaryotic neurotransmitter transporters obtained through structural snapshots of LeuT.

  8. Antidepressant binding site in a bacterial homologue of neurotransmitter transporters.

    PubMed

    Singh, Satinder K; Yamashita, Atsuko; Gouaux, Eric

    2007-08-23

    Sodium-coupled transporters are ubiquitous pumps that harness pre-existing sodium gradients to catalyse the thermodynamically unfavourable uptake of essential nutrients, neurotransmitters and inorganic ions across the lipid bilayer. Dysfunction of these integral membrane proteins has been implicated in glucose/galactose malabsorption, congenital hypothyroidism, Bartter's syndrome, epilepsy, depression, autism and obsessive-compulsive disorder. Sodium-coupled transporters are blocked by a number of therapeutically important compounds, including diuretics, anticonvulsants and antidepressants, many of which have also become indispensable tools in biochemical experiments designed to probe antagonist binding sites and to elucidate transport mechanisms. Steady-state kinetic data have revealed that both competitive and noncompetitive modes of inhibition exist. Antagonist dissociation experiments on the serotonin transporter (SERT) have also unveiled the existence of a low-affinity allosteric site that slows the dissociation of inhibitors from a separate high-affinity site. Despite these strides, atomic-level insights into inhibitor action have remained elusive. Here we screen a panel of molecules for their ability to inhibit LeuT, a prokaryotic homologue of mammalian neurotransmitter sodium symporters, and show that the tricyclic antidepressant (TCA) clomipramine noncompetitively inhibits substrate uptake. Cocrystal structures show that clomipramine, along with two other TCAs, binds in an extracellular-facing vestibule about 11 A above the substrate and two sodium ions, apparently stabilizing the extracellular gate in a closed conformation. Off-rate assays establish that clomipramine reduces the rate at which leucine dissociates from LeuT and reinforce our contention that this TCA inhibits LeuT by slowing substrate release. Our results represent a molecular view into noncompetitive inhibition of a sodium-coupled transporter and define principles for the rational design of

  9. Antidepressant Binding Site in a Bacterial Homologue of Neurotransmitter Transporters

    SciTech Connect

    Singh,S.; Yamashita, A.; Gouaux, E.

    2007-01-01

    Sodium-coupled transporters are ubiquitous pumps that harness pre-existing sodium gradients to catalyse the thermodynamically unfavourable uptake of essential nutrients, neurotransmitters and inorganic ions across the lipid bilayer. Dysfunction of these integral membrane proteins has been implicated in glucose/galactose malabsorption, congenital hypothyroidism, Bartter's syndrome, epilepsy, depression, autism and obsessive-compulsive disorder. Sodium-coupled transporters are blocked by a number of therapeutically important compounds, including diuretics, anticonvulsants and antidepressants, many of which have also become indispensable tools in biochemical experiments designed to probe antagonist binding sites and to elucidate transport mechanisms. Steady-state kinetic data have revealed that both competitive and noncompetitive modes of inhibition exist. Antagonist dissociation experiments on the serotonin transporter (SERT) have also unveiled the existence of a low-affinity allosteric site that slows the dissociation of inhibitors from a separate high-affinity site. Despite these strides, atomic-level insights into inhibitor action have remained elusive. Here we screen a panel of molecules for their ability to inhibit LeuT, a prokaryotic homologue of mammalian neurotransmitter sodium symporters, and show that the tricyclic antidepressant (TCA) clomipramine noncompetitively inhibits substrate uptake. Cocrystal structures show that clomipramine, along with two other TCAs, binds in an extracellular-facing vestibule about 11 {angstrom} above the substrate and two sodium ions, apparently stabilizing the extracellular gate in a closed conformation. Off-rate assays establish that clomipramine reduces the rate at which leucine dissociates from LeuT and reinforce our contention that this TCA inhibits LeuT by slowing substrate release. Our results represent a molecular view into noncompetitive inhibition of a sodium-coupled transporter and define principles for the rational

  10. Selective transport of monoamine neurotransmitters by human plasma membrane monoamine transporter and organic cation transporter 3.

    PubMed

    Duan, Haichuan; Wang, Joanne

    2010-12-01

    The plasma membrane monoamine transporter (PMAT) and organic cation transporter 3 (OCT3) are the two most prominent low-affinity, high-capacity (i.e., uptake(2)) transporters for endogenous biogenic amines. Using the Flp-in system, we expressed human PMAT (hPMAT) and human OCT3 (hOCT3) at similar levels in human embryonic kidney 293 cells. Parallel and detailed kinetics analysis revealed distinct and seemingly complementary patterns for the two transporters in transporting monoamine neurotransmitters. hPMAT is highly selective toward serotonin (5-HT) and dopamine, with the rank order of transport efficiency (V(max)/K(m)) being: dopamine, 5-HT ≫ histamine, norepinephrine, epinephrine. The substrate preference of hPMAT toward these amines is substantially driven by large (up to 15-fold) distinctions in its apparent binding affinities (K(m)). In contrast, hOCT3 is less selective than hPMAT toward the monoamines, and the V(max)/K(m) rank order for hOCT3 is: histamine > norepinephrine, epinephrine > dopamine >5-HT. It is noteworthy that hOCT3 demonstrated comparable (≤2-fold difference) K(m) toward all amines, and distinctions in V(max) played an important role in determining its differential transport efficiency toward the monoamines. Real-time reverse transcription-polymerase chain reaction revealed that hPMAT is expressed at much higher levels than hOCT3 in most human brain areas, whereas hOCT3 is selectively and highly expressed in adrenal gland and skeletal muscle. Our results suggest that hOCT3 represents a major uptake(2) transporter for histamine, epinephrine, and norepinephrine. hPMAT, on the other hand, is a major uptake(2) transporter for 5-HT and dopamine and may play a more important role in transporting these two neurotransmitters in the central nervous system.

  11. Drosophila melanogaster as a genetic model system to study neurotransmitter transporters

    PubMed Central

    Martin, Ciara A.; Krantz, David E.

    2014-01-01

    The model genetic organism Drosophila melanogaster, commonly known as the fruit fly, uses many of the same neurotransmitters as mammals and very similar mechanisms of neurotransmitter storage, release and recycling. This system offers a variety of powerful molecular-genetic methods for the study of transporters, many of which would be difficult in mammalian models. We review here progress made using Drosophila to understand the function and regulation of neurotransmitter transporters and discuss future directions for its use. PMID:24704795

  12. P2Y Purinergic Regulation of the Glycine Neurotransmitter Transporters*

    PubMed Central

    Jiménez, Esperanza; Zafra, Francisco; Pérez-Sen, Raquel; Delicado, Esmerilda G.; Miras-Portugal, Maria Teresa; Aragón, Carmen; López-Corcuera, Beatriz

    2011-01-01

    The sodium- and chloride-coupled glycine neurotransmitter transporters (GLYTs) control the availability of glycine at glycine-mediated synapses. The mainly glial GLYT1 is the key regulator of the glycine levels in glycinergic and glutamatergic pathways, whereas the neuronal GLYT2 is involved in the recycling of synaptic glycine from the inhibitory synaptic cleft. In this study, we report that stimulation of P2Y purinergic receptors with 2-methylthioadenosine 5′-diphosphate in rat brainstem/spinal cord primary neuronal cultures and adult rat synaptosomes leads to the inhibition of GLYT2 and the stimulation of GLYT1 by a paracrine regulation. These effects are mainly mediated by the ADP-preferring subtypes P2Y1 and P2Y13 because the effects are partially reversed by the specific antagonists N6-methyl-2′-deoxyadenosine-3′,5′-bisphosphate and pyridoxal-5′-phosphate-6-azo(2-chloro-5-nitrophenyl)-2,4-disulfonate and are totally blocked by suramin. P2Y12 receptor is additionally involved in GLYT1 stimulation. Using pharmacological approaches and siRNA-mediated protein knockdown methodology, we elucidate the molecular mechanisms of GLYT regulation. Modulation takes place through a signaling cascade involving phospholipase C activation, inositol 1,4,5-trisphosphate production, intracellular Ca2+ mobilization, protein kinase C stimulation, nitric oxide formation, cyclic guanosine monophosphate production, and protein kinase G-I (PKG-I) activation. GLYT1 and GLYT2 are differentially sensitive to NO/cGMP/PKG-I both in brain-derived preparations and in heterologous systems expressing the recombinant transporters and P2Y1 receptor. Sensitivity to 2-methylthioadenosine 5′-diphosphate by GLYT1 and GLYT2 was abolished by small interfering RNA (siRNA)-mediated knockdown of nitric-oxide synthase. Our data may help define the role of GLYTs in nociception and pain sensitization. PMID:21245148

  13. Neurotransmitter Transporter-Like: A Male Germline-specific SLC6 Transporter Required for Drosophila Spermiogenesis

    PubMed Central

    Chatterjee, Nabanita; Rollins, Janet; Mahowald, Anthony P.; Bazinet, Christopher

    2011-01-01

    The SLC6 class of membrane transporters, known primarily as neurotransmitter transporters, is increasingly appreciated for its roles in nutritional uptake of amino acids and other developmentally specific functions. A Drosophila SLC6 gene, Neurotransmitter transporter-like (Ntl), is expressed only in the male germline. Mobilization of a transposon inserted near the 3′ end of the Ntl coding region yields male-sterile mutants defining a single complementation group. Germline transformation with Ntl cDNAs under control of male germline-specific control elements restores Ntl/Ntl homozygotes to normal fertility, indicating that Ntl is required only in the germ cells. In mutant males, sperm morphogenesis appears normal, with elongated, individualized and coiled spermiogenic cysts accumulating at the base of the testes. However, no sperm are transferred to the seminal vesicle. The level of polyglycylation of Ntl mutant sperm tubulin appears to be significantly lower than that of wild type controls. Glycine transporters are the most closely related SLC6 transporters to Ntl, suggesting that Ntl functions as a glycine transporter in developing sperm, where augmentation of the cytosolic pool of glycine may be required for the polyglycylation of the massive amounts of tubulin in the fly's giant sperm. The male-sterile phenotype of Ntl mutants may provide a powerful genetic system for studying the function of an SLC6 transporter family in a model organism. PMID:21298005

  14. Snapshot of antidepressants at work: the structure of neurotransmitter transporter proteins.

    PubMed

    Cuboni, Serena; Hausch, Felix

    2014-05-12

    In the sweet spot: Cocrystal structures of engineered neurotransmitter transporters reveal the binding mode of commonly prescribed antidepressants, providing a basis for a rational drug design for this class of proteins. The picture shows the structure of the dopamine transporter of Drosophila melanogaster in complex with the antidepressant nortriptyline.

  15. Classical neurotransmitters and neuropeptides involved in major depression in a multi-neurotransmitter system: a focus on antidepressant drugs.

    PubMed

    Werner, Felix-Martin; Coveñas, R

    2013-01-01

    We summarize the alterations of classical neurotransmitters and neuropeptides and the corresponding subreceptors involved in major depression. Neuronal circuits in the brainstem, hippocampus and hypothalamus are developed, since they can be used to derive a multimodal pharmacotherapy. In this sense, serotonin hypoactivity could occur through a strong presynaptic inhibition of glutaminergic neurons via the subtype 5 of metabotropic glutaminergic receptors, and noradrenaline hypoactivity could be due to an enhanced presynaptic inhibition of GABAergic neurons via GABAB receptors. In the hippocampus, dopamine hypoactivity leads to a decreased positive effect. In clinical trials, the antidepressant effect of drugs interfering with the mentioned subreceptors, for example the triple reuptake inhibitor amitifadine, is being investigated. Moreover, the alterations of neuropeptides, such as corticotropin-releasing hormone, neuropeptide Y and galanin are pointed out. The additional antidepressant effect of analogs, agonists and antagonists of the mentioned neuropeptides should be examined.

  16. Co-existence of Functionally Different Vesicular Neurotransmitter Transporters

    PubMed Central

    Münster-Wandowski, Agnieszka; Zander, Johannes-Friedrich; Richter, Karin; Ahnert-Hilger, Gudrun

    2016-01-01

    The vesicular transmitter transporters VGLUT, VGAT, VMAT2 and VAChT, define phenotype and physiological properties of neuronal subtypes. VGLUTs concentrate the excitatory amino acid glutamate, VGAT the inhibitory amino acid GABA, VMAT2 monoamines, and VAChT acetylcholine (ACh) into synaptic vesicle (SV). Following membrane depolarization SV release their content into the synaptic cleft. A strict segregation of vesicular transporters is mandatory for the precise functioning of synaptic communication and of neuronal circuits. In the last years, evidence accumulates that subsets of neurons express more than one of these transporters leading to synaptic co-release of different and functionally opposing transmitters and modulation of synaptic plasticity. Synaptic co-existence of transporters may change during pathological scenarios in order to ameliorate misbalances in neuronal activity. In addition, evidence increases that transporters also co-exist on the same vesicle providing another layer of regulation. Generally, vesicular transmitter loading relies on an electrochemical gradient ΔμH+ driven by the proton ATPase rendering the lumen of the vesicle with respect to the cytosol positive (Δψ) and acidic (ΔpH). While the activity of VGLUT mainly depends on the Δψ component, VMAT, VGAT and VAChT work best at a high ΔpH. Thus, a vesicular synergy of transporters depending on the combination may increase or decrease the filling of SV with the principal transmitter. We provide an overview on synaptic co-existence of vesicular transmitter transporters including changes in the excitatory/inhibitory balance under pathological conditions. Additionally, we discuss functional aspects of vesicular synergy of transmitter transporters. PMID:26909036

  17. Co-existence of Functionally Different Vesicular Neurotransmitter Transporters.

    PubMed

    Münster-Wandowski, Agnieszka; Zander, Johannes-Friedrich; Richter, Karin; Ahnert-Hilger, Gudrun

    2016-01-01

    The vesicular transmitter transporters VGLUT, VGAT, VMAT2 and VAChT, define phenotype and physiological properties of neuronal subtypes. VGLUTs concentrate the excitatory amino acid glutamate, VGAT the inhibitory amino acid GABA, VMAT2 monoamines, and VAChT acetylcholine (ACh) into synaptic vesicle (SV). Following membrane depolarization SV release their content into the synaptic cleft. A strict segregation of vesicular transporters is mandatory for the precise functioning of synaptic communication and of neuronal circuits. In the last years, evidence accumulates that subsets of neurons express more than one of these transporters leading to synaptic co-release of different and functionally opposing transmitters and modulation of synaptic plasticity. Synaptic co-existence of transporters may change during pathological scenarios in order to ameliorate misbalances in neuronal activity. In addition, evidence increases that transporters also co-exist on the same vesicle providing another layer of regulation. Generally, vesicular transmitter loading relies on an electrochemical gradient ΔμH(+) driven by the proton ATPase rendering the lumen of the vesicle with respect to the cytosol positive (Δψ) and acidic (ΔpH). While the activity of VGLUT mainly depends on the Δψ component, VMAT, VGAT and VAChT work best at a high ΔpH. Thus, a vesicular synergy of transporters depending on the combination may increase or decrease the filling of SV with the principal transmitter. We provide an overview on synaptic co-existence of vesicular transmitter transporters including changes in the excitatory/inhibitory balance under pathological conditions. Additionally, we discuss functional aspects of vesicular synergy of transmitter transporters.

  18. A putative vesicular transporter expressed in Drosophila mushroom bodies that mediates sexual behavior may define a neurotransmitter system.

    PubMed

    Brooks, Elizabeth S; Greer, Christina L; Romero-Calderón, Rafael; Serway, Christine N; Grygoruk, Anna; Haimovitz, Jasmine M; Nguyen, Bac T; Najibi, Rod; Tabone, Christopher J; de Belle, J Steven; Krantz, David E

    2011-10-20

    Vesicular transporters are required for the storage of all classical and amino acid neurotransmitters in synaptic vesicles. Some neurons lack known vesicular transporters, suggesting additional neurotransmitter systems remain unidentified. Insect mushroom bodies (MBs) are critical for several behaviors, including learning, but the neurotransmitters released by the intrinsic Kenyon cells (KCs) remain unknown. Likewise, KCs do not express a known vesicular transporter. We report the identification of a novel Drosophila gene portabella (prt) that is structurally similar to known vesicular transporters. Both larval and adult brains express PRT in the KCs of the MBs. Additional PRT cells project to the central complex and optic ganglia. prt mutation causes an olfactory learning deficit and an unusual defect in the male's position during copulation that is rescued by expression in KCs. Because prt is expressed in neurons that lack other known vesicular transporters or neurotransmitters, it may define a previously unknown neurotransmitter system responsible for sexual behavior and a component of olfactory learning.

  19. A putative vesicular transporter expressed in Drosophila mushroom bodies that mediates sexual behavior may define a novel neurotransmitter system

    PubMed Central

    Brooks, Elizabeth S.; Greer, Christina L.; Romero-Calderón, Rafael; Serway, Christine N.; Grygoruk, Anna; Haimovitz, Jasmine M.; Nguyen, Bac T.; Najibi, Rod; Tabone, Christopher J.; de Belle, J. Steven; Krantz, David E.

    2011-01-01

    Summary Storage and release of classical and amino acid neurotransmitters requires vesicular transporters. Some neurons lack known vesicular transporters, suggesting additional neurotransmitter systems remain unidentified. Insect mushroom bodies (MBs) are critical for several behaviors, including learning, but the neurotransmitters released by the intrinsic Kenyon cells (KCs) remain unknown. Likewise, KCs do not express a known vesicular transporter. We report the identification of a novel Drosophila gene portabella (prt) that is structurally similar to known vesicular transporters. Both larval and adult brains express PRT in the KCs of the MBs. Additional PRT cells project to the central complex and optic ganglia. prt mutation causes an olfactory learning deficit and an unusual defect in the male’s position during copulation that is rescued by expression in KCs. Since prt is expressed in neurons that lack other known vesicular transporters or neurotransmitters, it may define a previously unknown neurotransmitter system responsible for sexual behavior and a component of olfactory learning. PMID:22017990

  20. Structure and localisation of drug binding sites on neurotransmitter transporters.

    PubMed

    Ravna, Aina W; Sylte, Ingebrigt; Dahl, Svein G

    2009-10-01

    The dopamine (DAT), serotontin (SERT) and noradrenalin (NET) transporters are molecular targets for different classes of psychotropic drugs. The crystal structure of Aquifex aeolicus LeuT(Aa) was used as a template for molecular modeling of DAT, SERT and NET, and two putative drug binding sites (pocket 1 and 2) in each transporter were identified. Cocaine was docked into binding pocket 1 of DAT, corresponding to the leucine binding site in LeuT(Aa), which involved transmembrane helices (TMHs) 1, 3, 6 and 8. Clomipramine was docked into binding pocket 2 of DAT, involving TMHs 1, 3, 6, 10 and 11, and extracellular loops 4 and 6, corresponding to the clomipramine binding site in a crystal structure of a LeuT(Aa)-clomipramine complex. The structures of the proposed cocaine- and tricyclic antidepressant-binding sites may be of particular interest for the design of novel DAT interacting ligands.

  1. Common drugs inhibit human organic cation transporter 1 (OCT1)-mediated neurotransmitter uptake.

    PubMed

    Boxberger, Kelli H; Hagenbuch, Bruno; Lampe, Jed N

    2014-06-01

    The human organic cation transporter 1 (OCT1) is a polyspecific transporter involved in the uptake of positively charged and neutral small molecules in the liver. To date, few endogenous compounds have been identified as OCT1 substrates; more importantly, the effect of drugs on endogenous substrate transport has not been examined. In this study, we established monoamine neurotransmitters as substrates for OCT1, specifically characterizing serotonin transport in human embryonic kidney 293 cells. Kinetic analysis yielded a Km of 197 micomolar and a Vmax of 561 pmol/mg protein/minute for serotonin. Furthermore, we demonstrated that serotonin uptake was inhibited by diphenhydramine, fluoxetine, imatinib, and verapamil, with IC50 values in the low micromolar range. These results were recapitulated in primary human hepatocytes, suggesting that OCT1 plays a significant role in hepatic elimination of serotonin and that xenobiotics may alter the elimination of endogenous compounds as a result of interactions at the transporter level.

  2. Synaptic uptake and beyond: the sodium- and chloride-dependent neurotransmitter transporter family SLC6.

    PubMed

    Chen, Nian-Hang; Reith, Maarten E A; Quick, Michael W

    2004-02-01

    The SLC6 family is a diverse set of transporters that mediate solute translocation across cell plasma membranes by coupling solute transport to the cotransport of sodium and chloride down their electrochemical gradients. These transporters probably have 12 transmembrane domains, with cytoplasmic N- and C-terminal tails, and at least some may function as homo-oligomers. Family members include the transporters for the inhibitory neurotransmitters GABA and glycine, the aminergic transmitters norepinephrine, serotonin, and dopamine, the osmolytes betaine and taurine, the amino acid proline, and the metabolic compound creatine. In addition, this family includes a system B(0+) cationic and neutral amino acid transporter, and two transporters for which the solutes are unknown. In general, SLC6 transporters act to regulate the level of extracellular solute concentrations. In the central and the peripheral nervous system, these transporters can regulate signaling among neurons, are the sites of action of various drugs of abuse, and naturally occurring mutations in several of these proteins are associated with a variety of neurological disorders. For example, transgenic animals lacking specific aminergic transporters show profoundly disturbed behavioral phenotypes and probably represent excellent systems for investigating psychiatric disease. SLC6 transporters are also found in many non-neural tissues, including kidney, intestine, and testis, consistent with their diverse physiological roles. Transporters in this family represent attractive therapeutic targets because they are subject to multiple forms of regulation by many different signaling cascades, and because a number of pharmacological agents have been identified that act specifically on these proteins.

  3. The role of SNARE proteins in trafficking and function of neurotransmitter transporters.

    PubMed

    Quick, M W

    2006-01-01

    The SNARE hypothesis of vesicle fusion proposes that a series of protein-protein interactions governs the delivery of vesicles to various membrane targets such as the Golgi network and the plasma membrane. Key players in this process include members of the syntaxin family of membrane proteins. The first member identified in this family, syntaxin 1A, plays an essential role in the docking and fusion of neurotransmitter-containing vesicles to the presynaptic membrane of neurons. Syntaxin 1A and other syntaxin family members have also been shown to interact with, and directly regulate, a variety of ion channels. More recently, the family of plasma membrane neurotransmitter transporters, proteins that function in part to control transmitter levels in brain, have been shown to be direct targets of syntaxin 1A regulation. This regulation involves both the trafficking of transporters as well as the control of ion and transmitter flux through transporters. In this chapter, the functional effects of syntaxin-transporter interactions are reviewed, and how such interactions may regulate neuronal signaling are considered.

  4. Ligand Binding in the Extracellular Vestibule of the Neurotransmitter Transporter Homologue LeuT.

    PubMed

    Grouleff, Julie; Koldsø, Heidi; Miao, Yinglong; Schiøtt, Birgit

    2017-03-15

    The human monoamine transporters (MATs) facilitate the reuptake of monoamine neurotransmitters from the synaptic cleft. MATs are linked to a number of neurological diseases and are the targets of both therapeutic and illicit drugs. Until recently, no high-resolution structures of the human MATs existed, and therefore, studies of this transporter family have relied on investigations of the homologues bacterial transporters such as the leucine transporter LeuT, which has been crystallized in several conformational states. A two-substrate transport mechanism has been suggested for this transporter family, which entails that high-affinity binding of a second substrate in an extracellular site is necessary for the substrate in the central binding site to be transported. Compelling evidence for this mechanism has been presented, however, a number of equally compelling accounts suggest that the transporters function through a mechanism involving only a single substrate and a single high-affinity site. To shed light on this apparent contradiction, we have performed extensive molecular dynamics simulations of LeuT in the outward-occluded conformation with either one or two substrates bound to the transporter. We have also calculated the substrate binding affinity in each of the two proposed binding sites through rigorous free energy simulations. Results show that substrate binding is unstable in the extracellular vestibule and the substrate binding affinity within the suggested extracellular site is very low (0.2 and 3.3 M for the two dominant binding modes) compared to the central substrate binding site (14 nM). This suggests that for LeuT in the outward-occluded conformation only a single high-affinity substrate binding site exists.

  5. Substrate-modulated gating dynamics in a Na+-coupled neurotransmitter transporter homologue.

    PubMed

    Zhao, Yongfang; Terry, Daniel S; Shi, Lei; Quick, Matthias; Weinstein, Harel; Blanchard, Scott C; Javitch, Jonathan A

    2011-06-02

    Neurotransmitter/Na(+) symporters (NSSs) terminate neuronal signalling by recapturing neurotransmitter released into the synapse in a co-transport (symport) mechanism driven by the Na(+) electrochemical gradient. NSSs for dopamine, noradrenaline and serotonin are targeted by the psychostimulants cocaine and amphetamine, as well as by antidepressants. The crystal structure of LeuT, a prokaryotic NSS homologue, revealed an occluded conformation in which a leucine (Leu) and two Na(+) are bound deep within the protein. This structure has been the basis for extensive structural and computational exploration of the functional mechanisms of proteins with a LeuT-like fold. Subsequently, an 'outward-open' conformation was determined in the presence of the inhibitor tryptophan, and the Na(+)-dependent formation of a dynamic outward-facing intermediate was identified using electron paramagnetic resonance spectroscopy. In addition, single-molecule fluorescence resonance energy transfer imaging has been used to reveal reversible transitions to an inward-open LeuT conformation, which involve the movement of transmembrane helix TM1a away from the transmembrane helical bundle. We investigated how substrate binding is coupled to structural transitions in LeuT during Na(+)-coupled transport. Here we report a process whereby substrate binding from the extracellular side of LeuT facilitates intracellular gate opening and substrate release at the intracellular face of the protein. In the presence of alanine, a substrate that is transported ∼10-fold faster than leucine, we observed alanine-induced dynamics in the intracellular gate region of LeuT that directly correlate with transport efficiency. Collectively, our data reveal functionally relevant and previously hidden aspects of the NSS transport mechanism that emphasize the functional importance of a second substrate (S2) binding site within the extracellular vestibule. Substrate binding in this S2 site appears to act cooperatively

  6. Molecular characterization of the first aromatic nutrient transporter from the sodium neurotransmitter symporter family.

    PubMed

    Meleshkevitch, Ella A; Assis-Nascimento, Poincyane; Popova, Lyudmila B; Miller, Melissa M; Kohn, Andrea B; Phung, Elizabeth N; Mandal, Anita; Harvey, William R; Boudko, Dmitri Y

    2006-08-01

    Nutrient amino acid transporters (NATs, subfamily of sodium neurotransmitter symporter family SNF, a.k.a. SLC6) represent a set of phylogenetically and functionally related transport proteins, which perform intracellular absorption of neutral, predominantly essential amino acids. Functions of NATs appear to be critical for the development and survival in organisms. However, mechanisms of specific and synergetic action of various NAT members in the amino acid transport network are virtually unexplored. A new transporter, agNAT8, was cloned from the malaria vector mosquito Anopheles gambiae (SS). Upon heterologous expression in Xenopus oocytes it performs high-capacity, sodium-coupled (2:1) uptake of nutrients with a strong preference for aromatic catechol-branched substrates, especially phenylalanine and its derivatives tyrosine and L-DOPA, but not catecholamines. It represents a previously unknown SNF phenotype, and also appears to be the first sodium-dependent B(0) type transporter with a narrow selectivity for essential precursors of catecholamine synthesis pathways. It is strongly and specifically transcribed in absorptive and secretory parts of the larval alimentary canal and specific populations of central and peripheral neurons of visual-, chemo- and mechano-sensory afferents. We have identified a new SNF transporter with previously unknown phenotype and showed its important role in the accumulation and redistribution of aromatic substrates. Our results strongly suggest that agNAT8 is an important, if not the major, provider of an essential catechol group in the synthesis of catecholamines for neurochemical signaling as well as ecdysozoan melanization and sclerotization pathways, which may include cuticle hardening/coloring, wound curing, oogenesis, immune responses and melanization of pathogens.

  7. LeuT: a prokaryotic stepping stone on the way to a eukaryotic neurotransmitter transporter structure.

    PubMed

    Singh, Satinder K

    2008-01-01

    Ion-coupled secondary transport is utilized by a broad range of integral membrane proteins to catalyze the energetically unfavorable movement of solute molecules across a lipid bilayer. Members of the solute carrier 6 (SLC6) family, present in both prokaryotes and eukaryotes, are sodium-coupled symporters that play crucial roles in processes as diverse as nutrient uptake and neurotransmitter clearance. The crystal structure of LeuT, a bacterial member of this family, provided the first atomic-level glimpse into overall architecture, pinpointed the substrate and sodium binding sites and implicated candidate helices and residues in the "gating" conformational changes that accompany ion binding and release. The structure is consistent with a wealth of elegant biochemical data on the eukaryotic counterparts and has for the first time permitted the construction of accurate homology models that can be directly tested experimentally. Sequence identity is especially high near the substrate and sodium binding sites and, thus, molecular insights within these regions have been substantial. However, there are several topics relevant to transport mechanism, inhibition and regulation that structure/function studies of LeuT cannot adequately address, suggesting the need for a eukaryotic transporter crystal structure.

  8. Antibody-Conjugated Single Quantum Dot Tracking of Membrane Neurotransmitter Transporters in Primary Neuronal Cultures.

    PubMed

    Bailey, Danielle M; Kovtun, Oleg; Rosenthal, Sandra J

    2017-01-01

    Single particle tracking (SPT) experiments have provided the scientific community with invaluable single-molecule information about the dynamic regulation of individual receptors, transporters, kinases, lipids, and molecular motors. SPT is an alternative to ensemble averaging approaches, where heterogeneous modes of motion might be lost. Quantum dots (QDs) are excellent probes for SPT experiments due to their photostability, high brightness, and size-dependent, narrow emission spectra. In a typical QD-based SPT experiment, QDs are bound to the target of interest and imaged for seconds to minutes via fluorescence video microscopy. Single QD spots in individual frames are then linked to form trajectories that are analyzed to determine their mean square displacement, diffusion coefficient, confinement index, and instantaneous velocity. This chapter describes a generalizable protocol for the single particle tracking of membrane neurotransmitter transporters on cell membranes with either unmodified extracellular antibody probes and secondary antibody-conjugated quantum dots or biotinylated extracellular antibody probes and streptavidin-conjugated quantum dots in primary neuronal cultures. The neuronal cell culture, the biotinylation protocol and the quantum dot labeling procedures, as well as basic data analysis are discussed.

  9. Mefloquine and Psychotomimetics Share Neurotransmitter Receptor and Transporter Interactions In Vitro

    PubMed Central

    Janowsky, Aaron; Eshleman, Amy J.; Johnson, Robert A.; Wolfrum, Katherine M.; Hinrichs, David J.; Yang, Jongtae; Zabriskie, T. Mark; Smilkstein, Martin J.; Riscoe, Michael K.

    2014-01-01

    Rationale Mefloquine is used for the prevention and treatment of chloroquine-resistant malaria, but its use is associated with nightmares, hallucinations, and exacerbation of symptoms of post-traumatic stress disorder. We hypothesized that potential mechanisms of action for the adverse psychotropic effects of mefloquine resemble those of other known psychotomimetics. Objectives Using in vitro radioligand binding and functional assays, we examined the interaction of (+)- and (−)-mefloquine enantiomers, the non-psychotomimetic anti-malarial agent, chloroquine, and several hallucinogens and psychostimulants with recombinant human neurotransmitter receptors and transporters. Results Hallucinogens and mefloquine bound stereoselectively and with relatively high affinity (Ki = 0.71–341 nM) to serotonin (5-HT) 2A but not 5-HT1A or 5-HT2C receptors. Mefloquine but not chloroquine was a partial 5-HT2A agonist and a full 5-HT2C agonist, stimulating inositol phosphate accumulation, with similar potency and efficacy as the hallucinogen dimethyltryptamine (DMT). 5-HT receptor antagonists blocked mefloquine’s effects. Mefloquine had low or no affinity for dopamine D1, D2, D3, and D4.4 receptors, or dopamine and norepinephrine transporters. However, mefloquine was a very low potency antagonist at the D3 receptor and mefloquine but not chloroquine or hallucinogens blocked [3H]5-HT uptake by the 5-HT transporter. Conclusions Mefloquine but not chloroquine shares an in vitro receptor interaction profile with some hallucinogens and this neurochemistry may be relevant to the adverse neuropsychiatric effects associated with mefloquine use by a small percentage of patients. Additionally, evaluating interactions with this panel of receptors and transporters may be useful for characterizing effects of other psychotropic drugs and for avoiding psychotomimetic effects for new pharmacotherapies, including antimalarial quinolines. PMID:24488404

  10. Two Na+ Sites Control Conformational Change in a Neurotransmitter Transporter Homolog.

    PubMed

    Tavoulari, Sotiria; Margheritis, Eleonora; Nagarajan, Anu; DeWitt, David C; Zhang, Yuan-Wei; Rosado, Edwin; Ravera, Silvia; Rhoades, Elizabeth; Forrest, Lucy R; Rudnick, Gary

    2016-01-15

    In LeuT, a prokaryotic homolog of neurotransmitter transporters, Na(+) stabilizes outward-open conformational states. We examined how each of the two LeuT Na(+) binding sites contributes to Na(+)-dependent closure of the cytoplasmic pathway using biochemical and biophysical assays of conformation. Mutating either of two residues that contribute to the Na2 site completely prevented cytoplasmic closure in response to Na(+), suggesting that Na2 is essential for this conformational change, whereas Na1 mutants retained Na(+) responsiveness. However, mutation of Na1 residues also influenced the Na(+)-dependent conformational change in ways that varied depending on the position mutated. Computational analyses suggest those mutants influence the ability of Na1 binding to hydrate the substrate pathway and perturb an interaction network leading to the extracellular gate. Overall, the results demonstrate that occupation of Na2 stabilizes outward-facing conformations presumably through a direct interaction between Na(+) and transmembrane helices 1 and 8, whereas Na(+) binding at Na1 influences conformational change through a network of intermediary interactions. The results also provide evidence that N-terminal release and helix motions represent distinct steps in cytoplasmic pathway opening.

  11. Two Na+ Sites Control Conformational Change in a Neurotransmitter Transporter Homolog*

    PubMed Central

    Tavoulari, Sotiria; Margheritis, Eleonora; Nagarajan, Anu; DeWitt, David C.; Zhang, Yuan-Wei; Rosado, Edwin; Ravera, Silvia; Rhoades, Elizabeth; Forrest, Lucy R.; Rudnick, Gary

    2016-01-01

    In LeuT, a prokaryotic homolog of neurotransmitter transporters, Na+ stabilizes outward-open conformational states. We examined how each of the two LeuT Na+ binding sites contributes to Na+-dependent closure of the cytoplasmic pathway using biochemical and biophysical assays of conformation. Mutating either of two residues that contribute to the Na2 site completely prevented cytoplasmic closure in response to Na+, suggesting that Na2 is essential for this conformational change, whereas Na1 mutants retained Na+ responsiveness. However, mutation of Na1 residues also influenced the Na+-dependent conformational change in ways that varied depending on the position mutated. Computational analyses suggest those mutants influence the ability of Na1 binding to hydrate the substrate pathway and perturb an interaction network leading to the extracellular gate. Overall, the results demonstrate that occupation of Na2 stabilizes outward-facing conformations presumably through a direct interaction between Na+ and transmembrane helices 1 and 8, whereas Na+ binding at Na1 influences conformational change through a network of intermediary interactions. The results also provide evidence that N-terminal release and helix motions represent distinct steps in cytoplasmic pathway opening. PMID:26582198

  12. Draft Genome Sequences of Lactobacillus plantarum Strain 90sk and Lactobacillus brevis Strain 15f: Focusing on Neurotransmitter Genes

    PubMed Central

    Yunes, Roman A.; Klimina, Ksenia M.; Emelyanov, Kirill V.; Zakharevich, Natalia V.; Poluektova, Elena U.

    2015-01-01

    The genomes of Lactobacillus plantarum strain 90sk and Lactobacillus brevis strain 15f were isolated from human intestinal microbiota. Both strains synthesize gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter. Detailed genome analyses will help to understand the role of GABA in the interaction of bacteria with human intestinal cells. PMID:25883284

  13. Draft Genome Sequences of Lactobacillus plantarum Strain 90sk and Lactobacillus brevis Strain 15f: Focusing on Neurotransmitter Genes.

    PubMed

    Yunes, Roman A; Klimina, Ksenia M; Emelyanov, Kirill V; Zakharevich, Natalia V; Poluektova, Elena U; Danilenko, Valery N

    2015-04-16

    The genomes of Lactobacillus plantarum strain 90sk and Lactobacillus brevis strain 15f were isolated from human intestinal microbiota. Both strains synthesize gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter. Detailed genome analyses will help to understand the role of GABA in the interaction of bacteria with human intestinal cells.

  14. Human neurons express the polyspecific cation transporter hOCT2, which translocates monoamine neurotransmitters, amantadine, and memantine.

    PubMed

    Busch, A E; Karbach, U; Miska, D; Gorboulev, V; Akhoundova, A; Volk, C; Arndt, P; Ulzheimer, J C; Sonders, M S; Baumann, C; Waldegger, S; Lang, F; Koepsell, H

    1998-08-01

    Recently, we cloned the human cation transporter hOCT2, a member of a new family of polyspecific transporters from kidney, and demonstrated electrogenic uptake of tetraethylammonium, choline, N1-methylnicotinamide, and 1-methyl-4-phenylpyridinium. Using polymerase chain reaction amplification, cDNA sequencing, in situ hybridization, and immunohistochemistry, we now show that hOCT2 message and protein are expressed in neurons of the cerebral cortex and in various subcortical nuclei. In Xenopus laevis oocytes expressing hOCT2, electrogenic transport of norepinephrine, histamine, dopamine, serotonin, and the antiparkinsonian drugs memantine and amantadine was demonstrated by tracer influx, tracer efflux, electrical measurements, or a combination. Apparent Km values of 1.9 +/- 0.6 mM (norepinephrine), 1.3 +/- 0.3 mM (histamine), 0.39 +/- 0.16 mM (dopamine), 80 +/- 20 microM (serotonin), 34 +/- 5 microM (memantine), and 27 +/- 3 microM (amantadine) were estimated. Measurement of trans-effects in depolarized oocytes and human embryonic kidney cells expressing hOCT2 suggests that there were different rates and specificities for cation influx and efflux. The hypothesis is raised that hOCT2 plays a physiological role in the central nervous system by regulating interstitial concentrations of monoamine neurotransmitters that have evaded high affinity uptake mechanisms. We show that amantadine does not interact with the expressed human Na+/Cl- dopamine cotransporter. However, concentrations of amantadine that are effective for the treatment of Parkinson's disease may increase the interstitial concentrations of dopamine and other aminergic neurotransmitters by competitive inhibition of hOCT2.

  15. Single-file diffusion and neurotransmitter transporters: Hodgkin and Keynes model revisited.

    PubMed

    DeFelice, L J; Adams, S V; Ypey, D L

    2001-01-01

    Norepinephrine transporters (NETs) use the Na gradient to remove norepinephrine (NE) from the synaptic cleft of adrenergic neurons following NE release from the presynaptic terminal. By coupling NE to the inwardly directed Na gradient, it is possible to concentrate NE inside cells. This mechanism, which is referred to as co-transport or secondary transport (Läuger, 1991, Electrogenic Ion Pumps, Sinauer Associates) is apparently universal: Na coupled transport applies to serotonin transporters (SERTs), dopamine transporters (DATs), glutamate transporters, and many others, including transporters for osmolites, metabolites and substrates such as sugar. Recently we have shown that NETs and SERTs transport norepinephrine or serotonin as if Na and the transmitter permeated through an ion channel together 'Galli et al., 1998, PNAS 95, 13260-13265; Petersen and DeFelice, 1999, Nature Neurosci. 2, 605-610'. These data are paradoxical because it has been difficult to envisage how NE, for example, would couple to Na if these ions move passively through an open pore. An 'alternating access' model is usually evoked to explain coupling: in such models NE and Na bind to NET, which then undergoes a conformational change to release NE and Na on the inside. The empty transporter then turns outward to complete the cycle. Alternating-access models never afford access to an open channel. Rather, substrates and co-transported ions are occluded in the transporter and carried across the membrane. The coupling mechanism we propose is fundamentally different than the coupling mechanism evoked in the alternating access model. To explain coupling in co-transporters, we use a mechanism first evoked by 'Hodgkin and Keynes (1955) J. Physiol. 128, 61-88' to explain ion interactions in K-selective channels. In the Hodgkin and Keynes model, K ions move single-file through a long narrow pore. Their model accounted for the inward/outward flux ratio if they assumed that two K ions queue within the

  16. Strategies for immunohistochemical protein localization using antibodies: What did we learn from neurotransmitter transporters in glial cells and neurons.

    PubMed

    Danbolt, Niels Christian; Zhou, Yun; Furness, David N; Holmseth, Silvia

    2016-12-01

    Immunocytochemistry and Western blotting are still major methods for protein localization, but they rely on the specificity of the antibodies. Validation of antibody specificity remains challenging mostly because ideal negative controls are often unavailable. Further, immunochemical labeling patterns are also influenced by a number of other factors such as postmortem changes, fixation procedures and blocking agents as well as the general assay conditions (e.g., buffers, temperature, etc.). Western blotting similarly depends on tissue collection and sample preparation as well as the electrophoretic separation, transfer to blotting membranes and the immunochemical probing of immobilized molecules. Publication of inaccurate information on protein distribution has downstream consequences for other researchers because the interpretation of physiological and pharmacological observations depends on information on where ion channels, receptors, enzymes or transporters are located. Despite numerous reports, some of which are strongly worded, erroneous localization data are being published. Here we describe the extent of the problem and illustrate the nature of the pitfalls with examples from studies of neurotransmitter transporters. We explain the importance of supplementing immunochemical observations with other measurements (e.g., mRNA levels and distribution, protein activity, mass spectrometry, electrophysiological recordings, etc.) and why quantitative considerations are integral parts of the quality control. Further, we propose a practical strategy for researchers who plan to embark on a localization study. We also share our thoughts about guidelines for quality control. GLIA 2016;64:2045-2064.

  17. Molecular dynamics simulations of Na+/Cl(-)-dependent neurotransmitter transporters in a membrane-aqueous system.

    PubMed

    Jørgensen, Anne Marie; Tagmose, Lena; Jørgensen, Anne Marie M; Bøgesø, Klaus P; Peters, Günther H

    2007-06-01

    We have performed molecular dynamics simulations of a homology model of the human serotonin transporter (hSERT) in a membrane environment and in complex with either the natural substrate 5-HT or the selective serotonin reuptake inhibitor escitalopram. We have also included a transporter homologue, the Aquifex aeolicus leucine transporter (LeuT), in our study to evaluate the applicability of a simple and computationally attractive membrane system. Fluctuations in LeuT extracted from simulations are in good agreement with crystallographic B factors. Furthermore, key interactions identified in the X-ray structure of LeuT are maintained throughout the simulations indicating that our simple membrane system is suitable for studying the transmembrane protein hSERT in complex with 5-HT or escitalopram. For these transporter complexes, only relatively small fluctuations are observed in the ligand-binding cleft. Specific interactions responsible for ligand recognition, are identified in the hSERT-5HT and hSERT-escitalopram complexes. Our findings are in good agreement with predictions from mutagenesis studies.

  18. Modeling and dynamics of the inward-facing state of a Na+/Cl- dependent neurotransmitter transporter homologue.

    PubMed

    Shaikh, Saher Afshan; Tajkhorshid, Emad

    2010-08-26

    The leucine transporter (LeuT) has recently commanded exceptional attention due mainly to two distinctions; it provides the only crystal structures available for a protein homologous to the pharmacologically relevant neurotransmitter: sodium symporters (NSS), and, it exhibits a hallmark 5-TM inverted repeat ("LeuT-fold"), a fold recently discovered to also exist in several secondary transporter families, underscoring its general role in transporter function. Constructing the transport cycle of "LeuT-fold" transporters requires detailed structural and dynamic descriptions of the outward-facing (OF) and inward-facing (IF) states, as well as the intermediate states. To this end, we have modeled the structurally unknown IF state of LeuT, based on the known crystal structures of the OF state of LeuT and the IF state of vSGLT, a "LeuT-fold" transporter. The detailed methodology developed for the study combines structure-based alignment, threading, targeted MD and equilibrium MD, and can be applied to other proteins. The resulting IF-state models maintain the secondary structural features of LeuT. Water penetration and solvent accessibility calculations show that TM1, TM3, TM6 and TM8 line the substrate binding/unbinding pathway with TM10 and its pseudosymmetric partner, TM5, participating in the extracellular and intracellular halves of the lumen, respectively. We report conformational hotspots where notable changes in interactions occur between the IF and OF states. We observe Na2 exiting the LeuT-substrate- complex in the IF state, mainly due to TM1 bending. Inducing a transition in only one of the two pseudosymmetric domains, while allowing the second to respond dynamically, is found to be sufficient to induce the formation of the IF state. We also propose that TM2 and TM7 may be facilitators of TM1 and TM6 motion. Thus, this study not only presents a novel modeling methodology applied to obtain the IF state of LeuT, but also describes structural elements involved in

  19. Azidobupramine, an Antidepressant-Derived Bifunctional Neurotransmitter Transporter Ligand Allowing Covalent Labeling and Attachment of Fluorophores

    PubMed Central

    Werner, Anna M.; Cuboni, Serena; Rudolf, Georg C.; Höfner, Georg; Wanner, Klaus T.; Sieber, Stephan A.; Schmidt, Ulrike; Holsboer, Florian; Rein, Theo; Hausch, Felix

    2016-01-01

    The aim of this study was to design, synthesize and validate a multifunctional antidepressant probe that is modified at two distinct positions. The purpose of these modifications was to allow covalent linkage of the probe to interaction partners, and decoration of probe-target complexes with fluorescent reporter molecules. The strategy for the design of such a probe (i.e., azidobupramine) was guided by the need for the introduction of additional functional groups, conveying the required properties while keeping the additional moieties as small as possible. This should minimize the risk of changing antidepressant-like properties of the new probe azidobupramine. To control for this, we evaluated the binding parameters of azidobupramine to known target sites such as the transporters for serotonin (SERT), norepinephrine (NET), and dopamine (DAT). The binding affinities of azidobupramine to SERT, NET, and DAT were in the range of structurally related and clinically active antidepressants. Furthermore, we successfully visualized azidobupramine-SERT complexes not only in SERT-enriched protein material but also in living cells stably overexpressing SERT. To our knowledge, azidobupramine is the first structural analogue of a tricyclic antidepressant that can be covalently linked to target structures and further attached to reporter molecules while preserving antidepressant-like properties and avoiding radioactive isotopes. PMID:26863431

  20. Dendritic Release of Neurotransmitters.

    PubMed

    Ludwig, Mike; Apps, David; Menzies, John; Patel, Jyoti C; Rice, Margaret E

    2016-12-06

    Release of neuroactive substances by exocytosis from dendrites is surprisingly widespread and is not confined to a particular class of transmitters: it occurs in multiple brain regions, and includes a range of neuropeptides, classical neurotransmitters, and signaling molecules, such as nitric oxide, carbon monoxide, ATP, and arachidonic acid. This review is focused on hypothalamic neuroendocrine cells that release vasopressin and oxytocin and midbrain neurons that release dopamine. For these two model systems, the stimuli, mechanisms, and physiological functions of dendritic release have been explored in greater detail than is yet available for other neurons and neuroactive substances. © 2017 American Physiological Society. Compr Physiol 7:235-252, 2017.

  1. Methionine uptake in Corynebacterium glutamicum by MetQNI and by MetPS, a novel methionine and alanine importer of the NSS neurotransmitter transporter family.

    PubMed

    Trötschel, Christian; Follmann, Martin; Nettekoven, Jeannine A; Mohrbach, Tobias; Forrest, Lucy R; Burkovski, Andreas; Marin, Kay; Krämer, Reinhard

    2008-12-02

    The soil bacterium Corynebacterium glutamicum is a model organism in amino acid biotechnology. Here we present the identification of two different L-methionine uptake systems including the first characterization of a bacterial secondary methionine carrier. The primary carrier MetQNI is a high affinity ABC-type transporter specific for l-methionine. Its expression is under the control of the transcription factor McbR, the global regulator of sulfur metabolism in C. glutamicum. Besides MetQNI, a novel secondary methionine uptake system of the NSS (neurotransmitter:sodium symporter) family was identified and named MetP. The MetP system is characterized by a lower affinity for methionine and uses Na(+) ions for energetic coupling. It is also the main alanine transporter in C. glutamicum and is expressed constitutively. These observations are consistent with models of methionine, alanine, and leucine bound to MetP, derived from the X-ray crystal structure of the LeuT transporter from Aquifex aeolicus. Complementation studies show that MetP consists of two components, a large subunit with 12 predicted transmembrane segments and, surprisingly, an additional subunit with one predicted transmembrane segment only. Thus, this new member of the NSS transporter family adds a novel feature to this class of carriers, namely, the functional dependence on an additional small subunit.

  2. The lipid habitats of neurotransmitter receptors in brain.

    PubMed

    Borroni, María Virginia; Vallés, Ana Sofía; Barrantes, Francisco J

    2016-11-01

    Neurotransmitter receptors, the macromolecules specialized in decoding the chemical signals encrypted in the chemical signaling mechanism in the nervous system, occur either at the somatic cell surface of chemically excitable cells or at specialized subcellular structures, the synapses. Synapses have lipid compositions distinct from the rest of the cell membrane, suggesting that neurotransmitter receptors and their scaffolding and adaptor protein partners require specific lipid habitats for optimal operation. In this review we discuss some paradigmatic cases of neurotransmitter receptor-lipid interactions, highlighting the chemical nature of the intervening lipid species and providing examples of the receptor mechanisms affected by interaction with lipids. The focus is on the effects of cholesterol, glycerophospholipids and covalent fatty acid acylation on neurotransmitter receptors. We also briefly discuss the role of lipid phase states involving lateral heterogeneities of the host membrane known to modulate membrane transport, protein sorting and signaling. Modulation of neurotransmitter receptors by lipids occurs at multiple levels, affecting a wide span of activities including their trafficking, sorting, stability, residence lifetime at the cell surface, endocytosis, and recycling, among other important functional properties at the synapse.

  3. Development of a novel high-throughput assay for the investigation of GlyT-1b neurotransmitter transporter function.

    PubMed

    Allan, Lynda; Leith, J Lianne; Papakosta, Marianthi; Morrow, John A; Irving, Nicholas G; McFerran, Brian W; Clark, Alan G

    2006-01-01

    The glycine transporter (GlyT-1b) is a Na(+)/Cl(-)-dependent electrogenic transporter which mediates the rapid re-uptake of glycine from the synaptic cleft. Based on its tissue distribution, GlyT-1 has been suggested to co-localise with the NMDA receptor where it may modulate the concentration of glycine at its co-agonist binding site. This data has led to GlyT-1 inhibitors being proposed as targets for disorders such as schizophrenia and cognitive dysfunction. Radiolabelled uptake assays (e.g. [(3)H]glycine) have been traditionally used in compound screening to identify glycine transporter inhibitors. While such an assay format is useful for testing limited numbers of compounds, the identification of novel glycine uptake inhibitors requires a functional assay compatible with high-throughput screening (HTS) of large compound libraries. Here, the authors present the development of a novel homogenous cell-based assay using the FLIPR membrane potential blue dye (Molecular Devices) and FLEXstation. Pharmacological data for the GlyT-1 inhibitors Org 24598 and ALX 5407 obtained using this novel electrogenic assay correlated well with the conventional [(3)H]-glycine uptake assay format. Furthermore, the assay has been successfully miniaturised using FLIPR(3) and therefore has the potential to be used for high-throughput screening.

  4. Is Aspartate an Excitatory Neurotransmitter?

    PubMed Central

    Herring, Bruce E.; Silm, Katlin

    2015-01-01

    Recent evidence has resurrected the idea that the amino acid aspartate, a selective NMDA receptor agonist, is a neurotransmitter. Using a mouse that lacks the glutamate-selective vesicular transporter VGLUT1, we find that glutamate alone fully accounts for the activation of NMDA receptors at excitatory synapses in the hippocampus. This excludes a role for aspartate and, by extension, a recently proposed role for the sialic acid transporter sialin in excitatory transmission. SIGNIFICANCE STATEMENT It has been proposed that the amino acid aspartate serves as a neurotransmitter. Although aspartate is a selective agonist for NMDA receptors, we find that glutamate alone fully accounts for neurotransmission at excitatory synapses in the hippocampus, excluding a role for aspartate. PMID:26180193

  5. How did the neurotransmitter cross the bilayer? A closer view.

    PubMed

    Sonders, Mark S; Quick, Matthias; Javitch, Jonathan A

    2005-06-01

    Plasma membrane neurotransmitter transporters for monoamines, GABA, glycine and excitatory amino acids are homologous to two sizable families of bacterial amino acid transporters. Recently, a high resolution structure was determined for a thermophilic glutamate transporter. Also, a bacterial tryptophan transporter related to the family of biogenic amine neurotransmitter transporters was functionally expressed. Structural insights from these and other bacterial transporters will help to rationalize the mechanisms for the increasingly complex functions that have been described for mammalian transporters, in addition to their modes of regulation. We touch on recent insights into the functions of neurotransmitter transporters in their physiological contexts.

  6. The putative Na⁺/Cl⁻-dependent neurotransmitter/osmolyte transporter inebriated in the Drosophila hindgut is essential for the maintenance of systemic water homeostasis.

    PubMed

    Luan, Zhuo; Quigley, Caitlin; Li, Hong-Sheng

    2015-01-23

    Most organisms are able to maintain systemic water homeostasis over a wide range of external or dietary osmolarities. The excretory system, composed of the kidneys in mammals and the Malpighian tubules and hindgut in insects, can increase water conservation and absorption to maintain systemic water homeostasis, which enables organisms to tolerate external hypertonicity or desiccation. However, the mechanisms underlying the maintenance of systemic water homeostasis by the excretory system have not been fully characterized. In the present study, we found that the putative Na(+)/Cl(-)-dependent neurotransmitter/osmolyte transporter inebriated (ine) is expressed in the basolateral membrane of anterior hindgut epithelial cells. This was confirmed by comparison with a known basolateral localized protein, the α subunit of Na(+)-K(+) ATPase (ATPα). Under external hypertonicity, loss of ine in the hindgut epithelium results in severe dehydration without damage to the hindgut epithelial cells, implicating a physiological failure of water conservation/absorption. We also found that hindgut expression of ine is required for water conservation under desiccating conditions. Importantly, specific expression of ine in the hindgut epithelium can completely restore disrupted systemic water homeostasis in ine mutants under both conditions. Therefore, ine in the Drosophila hindgut is essential for the maintenance of systemic water homeostasis.

  7. Transverse centroid oscillations in solenoidially focused beam transport lattices

    SciTech Connect

    Lund, Steven M.; Wootton, Christopher J.; Lee, Edward P.

    2008-08-01

    Linear equations of motion are derived that describe small-amplitude centroid oscillations induced by displacement and rotational misalignments of the focusing solenoids in the transport lattice, dipole steering elements, and initial centroid offset errors. These equations are analyzed in a local rotating Larmor frame to derive complex-variable"alignment functions" and"bending functions" that efficiently describe the characteristics of the centroid oscillations induced by mechanical misalignments of the solenoids and dipole steering elements. The alignment and bending functions depend only on properties of the ideal lattice in the absence of errors and steering and have associated expansion amplitudes set by the misalignments and steering fields. Applications of this formulation are presented for statistical analysis of centroid deviations, calculation of actual lattice misalignments from centroid measurements, and optimal beam steering.

  8. Transverse Centroid Oscillations in Solenoidially Focused Beam Transport Lattices

    SciTech Connect

    Lund, S M; Wootton, C J; Lee, E P

    2008-08-01

    Linear equations of motion are derived that describe small-amplitude centroid oscillations induced by displacement and rotational misalignments of the focusing solenoids in the transport lattice, dipole steering elements, and initial centroid offset errors. These equations are analyzed in a local rotating Larmor frame to derive complex-variable 'alignment functions' and 'bending functions' that efficiently describe the characteristics of the centroid oscillations induced by mechanical misalignments of the solenoids and dipole steering elements. The alignment and bending functions depend only on properties of the ideal lattice in the absence of errors and steering and have associated expansion amplitudes set by the misalignments and steering fields. Applications of this formulation are presented for statistical analysis of centroid deviations, calculation of actual lattice misalignments from centroid measurements, and optimal beam steering.

  9. Electrochemical Analysis of Neurotransmitters

    NASA Astrophysics Data System (ADS)

    Bucher, Elizabeth S.; Wightman, R. Mark

    2015-07-01

    Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements.

  10. Electrochemical Analysis of Neurotransmitters

    PubMed Central

    Bucher, Elizabeth S.; Wightman, R. Mark

    2016-01-01

    Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements. PMID:25939038

  11. Electrochemical Analysis of Neurotransmitters.

    PubMed

    Bucher, Elizabeth S; Wightman, R Mark

    2015-01-01

    Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements.

  12. Solenoidal Fields for Ion Beam Transport and Focusing

    SciTech Connect

    Lee, Edward P.; Leitner, Matthaeus

    2007-11-01

    In this report we calculate time-independent fields of solenoidal magnets that are suitable for ion beam transport and focusing. There are many excellent Electricity and Magnetism textbooks that present the formalism for magnetic field calculations and apply it to simple geometries [1-1], but they do not include enough relevant detail to be used for designing a charged particle transport system. This requires accurate estimates of fringe field aberrations, misaligned and tilted fields, peak fields in wire coils and iron, external fields, and more. Specialized books on magnet design, technology, and numerical computations [1-2] provide such information, and some of that is presented here. The AIP Conference Proceedings of the US Particle Accelerator Schools [1-3] contain extensive discussions of design and technology of magnets for ion beams - except for solenoids. This lack may be due to the fact that solenoids have been used primarily to transport and focus particles of relatively low momenta, e.g. electrons of less than 50 MeV and protons or H- of less than 1.0 MeV, although this situation may be changing with the commercial availability of superconducting solenoids with up to 20T bore field [1-4]. Internal reports from federal laboratories and industry treat solenoid design in detail for specific applications. The present report is intended to be a resource for the design of ion beam drivers for Inertial Fusion Energy [1-5] and Warm Dense Matter experiments [1-6], although it should also be useful for a broader range of applications. The field produced by specified currents and material magnetization can always be evaluated by solving Maxwell's equations numerically, but it is also desirable to have reasonably accurate, simple formulas for conceptual system design and fast-running beam dynamics codes, as well as for general understanding. Most of this report is devoted to such formulas, but an introduction to the Tosca{copyright} code [1-7] and some numerical

  13. Neurotransmitter transporter family including SLC6A6 and SLC6A13 contributes to the 5-aminolevulinic acid (ALA)-induced accumulation of protoporphyrin IX and photodamage, through uptake of ALA by cancerous cells.

    PubMed

    Tran, Tai Tien; Mu, Anfeng; Adachi, Yuka; Adachi, Yasushi; Taketani, Shigeru

    2014-01-01

    δ-Aminolevulinic acid (ALA)-induced protoporphyrin accumulation is widely used in the treatment of cancer, as photodynamic therapy (PDT). To clarify the mechanisms of ALA uptake by tumor cells, we have examined the ALA-induced accumulation of protoporphyrin by the treatment of colon cancer DLD-1 and epithelial cancer HeLa cells with γ-aminobutyric acid (GABA)-related compounds. When the cells were treated with GABA, taurine and β-alanine, the level of protoporphyrin was decreased, suggesting that plasma membrane transporters involved in the transport of neurotransmitters contribute to the uptake of ALA. By transfection with neurotransmitter transporters SLC6A6, SLC6A8 and SLC6A13 cDNA, the ALA- and ALA methylester-dependent accumulation of protoporphyrin markedly increased in HEK293T cells, dependent on an increase in the uptake of ALA. When ALA-treated cells were exposed to white light, the extent of photodamage increased in SLC6A6- and SLC6A13-expressing cells. Conversely, knockdown of SLC6A6 or SLC6A13 with siRNAs in DLD-1 and HeLa cells decreased the ALA-induced accumulation. The expression of SLC6A6 and SLC6A13 was found in some cancer cell lines. Immunohistochemical studies revealed that the presence of these transporters was elevated in colon cancerous cells. These results indicated that neurotransmitter transporters including SLC6A6 and SLC6A13 mediate the uptake of ALA and can play roles in the enhancement of ALA-induced accumulation of protoporphyrin in cancerous cells.

  14. Transportation training: Focusing on movement of hazardous substances and wastes

    SciTech Connect

    Jones, E.; Moreland, W.M.

    1988-01-01

    Over the past 25 years extensive federal legislation involving the handling and transport of hazardous materials/waste has been passed that has resulted in numerous overlapping regulations administered and enforced by different federal agencies. The handling and transport of hazardous materials/waste involves a significant number of workers who are subject to a varying degree of risk should an accident occur during handling or transport. Effective transportation training can help workers address these risks and mitigate them, and at the same time enable ORNL to comply with the federal regulations concerning the transport of hazardous materials/waste. This presentation will outline how the Environmental and Health Protection Division's Technical Resources and Training Program at the Oak Ridge National Laboratory, working with transportation and waste disposal personnel, are developing and implementing a comprehensive transportation safety training program to meet the needs of our workers while satisfying appropriate federal regulations. 8 refs., 5 figs., 3 tabs.

  15. Microsphere-chain waveguides: Focusing and transport properties

    SciTech Connect

    Allen, Kenneth W. Astratov, Vasily N.; Darafsheh, Arash; Abolmaali, Farzaneh; Mojaverian, Neda; Limberopoulos, Nicholaos I.; Lupu, Anatole

    2014-07-14

    It is shown that the focusing properties of polystyrene microsphere-chain waveguides (MCWs) formed by sufficiently large spheres (D ≥ 20λ, where D is the sphere diameter and λ is the wavelength of light) scale with the sphere diameter as predicted by geometrical optics. However, this scaling behavior does not hold for mesoscale MCWs with D ≤ 10λ resulting in a periodical focusing with gradually reducing beam waists and in extremely small propagation losses. The observed effects are related to properties of nanojet-induced and periodically focused modes in such structures. The results can be used for developing focusing microprobes, laser scalpels, and polarization filters.

  16. Stereoselectivity of chiral drug transport: a focus on enantiomer-transporter interaction.

    PubMed

    Zhou, Quan; Yu, Lu-Shan; Zeng, Su

    2014-08-01

    Drug transporters and drug metabolism enzymes govern drug absorption, distribution, metabolism and elimination. Many literature works presenting important aspects related to stereochemistry of drug metabolism are available. However, there is very little literature on stereoselectivity of chiral drug transport and enantiomer-transporter interaction. In recent years, the experimental research within this field showed good momentum. Herein, an up-to-date review on this topic was presented. Breast Cancer Resistance Protein (BCRP), Multidrug Resistance Proteins (MRP), P-glycoprotein (P-gp), Organic Anion Transporters (OATs), Organic Anion Transporting Polypeptides (OATPs), Organic Cation Transporters (OCTs), Peptide Transport Proteins (PepTs), Human Proton-Coupled Folate Transporter (PCFT) and Multidrug and Toxic Extrusion Proteins (MATEs), have been reported to exhibit either positive or negative enantio-selective substrate recognition. The approaches utilized to study chirality in enantiomer-transporter interaction include inhibition experiments of specific transporters in cell models (e.g. Caco-2 cells), transport study using drug resistance cell lines or transgenic cell lines expressing transporters in wild type or variant, the use of transporter knockout mice, pharmacokinetics association of single nucleotide polymorphism in transporters, pharmacokinetic interaction study of racemate in the presence of specific transporter inhibitor or inducer, molecule cellular membrane affinity chromatography and pharmacophore modeling. Enantiomer-enantiomer interactions exist in chiral transport. The strength and/or enantiomeric preference of stereoselectivity may be species or tissue-specific, concentration-dependent and transporter family member-dependent. Modulation of specific drug transporter by pure enantiomers might exhibit opposite stereoselectivity. Further studies with integrated approaches will open up new horizons in stereochemistry of pharmacokinetics.

  17. Stable two-plane focusing for emittance-dominated sheet-beam transport

    NASA Astrophysics Data System (ADS)

    Carlsten, B. E.; Earley, L. M.; Krawczyk, F. L.; Russell, S. J.; Potter, J. M.; Ferguson, P.; Humphries, S.

    2005-06-01

    Two-plane focusing of sheet electron beams will be an essential technology for an emerging class of high-power, 100 to 300 GHz rf sources [Carlsten et al., IEEE Trans. Plasma Sci. 33, 85 (2005), ITPSBD, 0093-3813, 10.1109/TPS.2004.841172]. In these devices, the beam has a unique asymmetry in which the transport is emittance dominated in the sheet’s thin dimension and space-charge dominated in the sheet’s wide dimension. Previous work has studied the stability of the transport of beams in the emittance-dominated regime for both wiggler and periodic permanent magnet (PPM) configurations with single-plane focusing, and has found that bigger envelope scalloping occurs for equilibrium transport, as compared to space-charge dominated beams [Carlsten et al., this issue, Phys. Rev. ST Accel. Beams 8, 062001 (2005), PRABFM, 1098-4402]. In this paper, we describe the differences in transport stability when two-plane focusing is included. Two-plane wiggler focusing degrades the transport stability slightly, whereas two-plane PPM focusing greatly compromises the transport. On the other hand, single-plane PPM focusing can be augmented with external quadrupole fields to provide weak focusing in the sheet’s wide dimension, which has stability comparable to two-plane wiggler transport.

  18. Challenges and recent advances in mass spectrometric imaging of neurotransmitters

    PubMed Central

    Gemperline, Erin; Chen, Bingming; Li, Lingjun

    2014-01-01

    Mass spectrometric imaging (MSI) is a powerful tool that grants the ability to investigate a broad mass range of molecules, from small molecules to large proteins, by creating detailed distribution maps of selected compounds. To date, MSI has demonstrated its versatility in the study of neurotransmitters and neuropeptides of different classes toward investigation of neurobiological functions and diseases. These studies have provided significant insight in neurobiology over the years and current technical advances are facilitating further improvements in this field. neurotransmitters, focusing specifically on the challenges and recent Herein, we advances of MSI of neurotransmitters. PMID:24568355

  19. Neurotransmitters of the suprachiasmatic nuclei

    PubMed Central

    Reghunandanan, Vallath; Reghunandanan, Rajalaxmy

    2006-01-01

    There has been extensive research in the recent past looking into the molecular basis and mechanisms of the biological clock, situated in the suprachiasmatic nuclei (SCN) of the anterior hypothalamus. Neurotransmitters are a very important component of SCN function. Thorough knowledge of neurotransmitters is not only essential for the understanding of the clock but also for the successful manipulation of the clock with experimental chemicals and therapeutical drugs. This article reviews the current knowledge about neurotransmitters in the SCN, including neurotransmitters that have been identified only recently. An attempt was made to describe the neurotransmitters and hormonal/diffusible signals of the SCN efference, which are necessary for the master clock to exert its overt function. The expression of robust circadian rhythms depends on the integrity of the biological clock and on the integration of thousands of individual cellular clocks found in the clock. Neurotransmitters are required at all levels, at the input, in the clock itself, and in its efferent output for the normal function of the clock. The relationship between neurotransmitter function and gene expression is also discussed because clock gene transcription forms the molecular basis of the clock and its working. PMID:16480518

  20. Increased oxidative metabolism and neurotransmitter cycling in the brain of mice lacking the thyroid hormone transporter SLC16A2 (MCT8).

    PubMed

    Rodrigues, Tiago B; Ceballos, Ainhoa; Grijota-Martínez, Carmen; Nuñez, Barbara; Refetoff, Samuel; Cerdán, Sebastian; Morte, Beatriz; Bernal, Juan

    2013-01-01

    Mutations of the monocarboxylate transporter 8 (MCT8) cause a severe X-linked intellectual deficit and neurological impairment. MCT8 is a specific thyroid hormone (T4 and T3) transporter and the patients also present unusual abnormalities in the serum profile of thyroid hormone concentrations due to altered secretion and metabolism of T4 and T3. Given the role of thyroid hormones in brain development, it is thought that the neurological impairment is due to restricted transport of thyroid hormones to the target neurons. In this work we have investigated cerebral metabolism in mice with Mct8 deficiency. Adult male mice were infused for 30 minutes with (1-(13)C) glucose and brain extracts prepared and analyzed by (13)C nuclear magnetic resonance spectroscopy. Genetic inactivation of Mct8 resulted in increased oxidative metabolism as reflected by increased glutamate C4 enrichment, and of glutamatergic and GABAergic neurotransmissions as observed by the increases in glutamine C4 and GABA C2 enrichments, respectively. These changes were distinct to those produced by hypothyroidism or hyperthyroidism. Similar increments in glutamate C4 enrichment and GABAergic neurotransmission were observed in the combined inactivation of Mct8 and D2, indicating that the increased neurotransmission and metabolic activity were not due to increased production of cerebral T3 by the D2-encoded type 2 deiodinase. In conclusion, Mct8 deficiency has important metabolic consequences in the brain that could not be correlated with deficiency or excess of thyroid hormone supply to the brain during adulthood.

  1. Mechanism of chloride interaction with neurotransmitter:sodium symporters.

    PubMed

    Zomot, Elia; Bendahan, Annie; Quick, Matthias; Zhao, Yongfang; Javitch, Jonathan A; Kanner, Baruch I

    2007-10-11

    Neurotransmitter:sodium symporters (NSS) have a critical role in regulating neurotransmission and are targets for psychostimulants, anti-depressants and other drugs. Whereas the non-homologous glutamate transporters mediate chloride conductance, in the eukaryotic NSS chloride is transported together with the neurotransmitter. In contrast, transport by the bacterial NSS family members LeuT, Tyt1 and TnaT is chloride independent. The crystal structure of LeuT reveals an occluded binding pocket containing leucine and two sodium ions, and is highly relevant for the neurotransmitter transporters. However, the precise role of chloride in neurotransmitter transport and the location of its binding site remain elusive. Here we show that introduction of a negatively charged amino acid at or near one of the two putative sodium-binding sites of the GABA (gamma-aminobutyric acid) transporter GAT-1 from rat brain (also called SLC6A1) renders both net flux and exchange of GABA largely chloride independent. In contrast to wild-type GAT-1, a marked stimulation of the rate of net flux, but not of exchange, was observed when the internal pH was lowered. Equivalent mutations introduced in the mouse GABA transporter GAT4 (SLC6A11) and the human dopamine transporter DAT (SLC6A3) also result in chloride-independent transport, whereas the reciprocal mutations in LeuT and Tyt1 render substrate binding and/or uptake by these bacterial NSS chloride dependent. Our data indicate that the negative charge, provided either by chloride or by the transporter itself, is required during binding and translocation of the neurotransmitter, probably to counterbalance the charge of the co-transported sodium ions.

  2. Increased Oxidative Metabolism and Neurotransmitter Cycling in the Brain of Mice Lacking the Thyroid Hormone Transporter Slc16a2 (Mct8)

    PubMed Central

    Rodrigues, Tiago B.; Ceballos, Ainhoa; Grijota-Martínez, Carmen; Nuñez, Barbara; Refetoff, Samuel; Cerdán, Sebastian; Morte, Beatriz; Bernal, Juan

    2013-01-01

    Mutations of the monocarboxylate transporter 8 (MCT8) cause a severe X-linked intellectual deficit and neurological impairment. MCT8 is a specific thyroid hormone (T4 and T3) transporter and the patients also present unusual abnormalities in the serum profile of thyroid hormone concentrations due to altered secretion and metabolism of T4 and T3. Given the role of thyroid hormones in brain development, it is thought that the neurological impairment is due to restricted transport of thyroid hormones to the target neurons. In this work we have investigated cerebral metabolism in mice with Mct8 deficiency. Adult male mice were infused for 30 minutes with (1-13C) glucose and brain extracts prepared and analyzed by 13C nuclear magnetic resonance spectroscopy. Genetic inactivation of Mct8 resulted in increased oxidative metabolism as reflected by increased glutamate C4 enrichment, and of glutamatergic and GABAergic neurotransmissions as observed by the increases in glutamine C4 and GABA C2 enrichments, respectively. These changes were distinct to those produced by hypothyroidism or hyperthyroidism. Similar increments in glutamate C4 enrichment and GABAergic neurotransmission were observed in the combined inactivation of Mct8 and D2, indicating that the increased neurotransmission and metabolic activity were not due to increased production of cerebral T3 by the D2-encoded type 2 deiodinase. In conclusion, Mct8 deficiency has important metabolic consequences in the brain that could not be correlated with deficiency or excess of thyroid hormone supply to the brain during adulthood. PMID:24098341

  3. Electrochemical nanoprobes for the chemical detection of neurotransmitters

    PubMed Central

    Colombo, Michelle L.

    2015-01-01

    Neurotransmitters, acting as chemical messengers, play an important role in neurotransmission, which governs many functional aspects of nervous system activity. Electrochemical probes have proven a very useful technique to study neurotransmission, especially to quantify and qualify neurotransmitters. With the emerging interests in probing neurotransmission at the level of single cells, single vesicles, as well as single synapses, probes that enable detection of neurotransmitters at the nanometer scale become vitally important. Electrochemical nanoprobes have been successfully employed in nanometer spatial resolution imaging of single nanopores of Si membrane and single Au nanoparticles, providing both topographical and chemical information, thus holding great promise for nanometer spatial study of neurotransmission. Here we present the current state of electrochemical nanoprobes for chemical detection of neurotransmitters, focusing on two types of nanoelectrodes, i.e. carbon nanoelectrode and nano-ITIES pipet electrode. PMID:26327927

  4. Emittance growth of an nonequilibrium intense electron beam in a transport channel with discrete focusing

    SciTech Connect

    Carlsten, B.E.

    1997-02-01

    The author analyzes the emittance growth mechanisms for a continuous, intense electron beam in a focusing transport channel, over distances short enough that the beam does not reach equilibrium. The emittance grows from the effect of nonlinear forces arising from (1) current density nonuniformities, (2) energy variations leading to nonlinearities in the space-charge force even if the current density is uniform, (3) axial variations in the radial vector potential, (4) an axial velocity shear along the beam, and (5) an energy redistribution of the beam as the beam compresses or expands. The emittance growth is studied analytically and numerically for the cases of balanced flow, tight focusing, and slight beam scalloping, and is additionally studied numerically for an existing 6-MeV induction linear accelerator. Rules for minimizing the emittance along a beamline are established. Some emittance growth will always occur, both from current density nonuniformities that arise along the transport and from beam radius changes along the transport.

  5. Heptanoate as a neural fuel: energetic and neurotransmitter precursors in normal and glucose transporter I-deficient (G1D) brain

    PubMed Central

    Marin-Valencia, Isaac; Good, Levi B; Ma, Qian; Malloy, Craig R; Pascual, Juan M

    2013-01-01

    It has been postulated that triheptanoin can ameliorate seizures by supplying the tricarboxylic acid cycle with both acetyl-CoA for energy production and propionyl-CoA to replenish cycle intermediates. These potential effects may also be important in other disorders associated with impaired glucose metabolism because glucose supplies, in addition to acetyl-CoA, pyruvate, which fulfills biosynthetic demands via carboxylation. In patients with glucose transporter type I deficiency (G1D), ketogenic diet fat (a source only of acetyl-CoA) reduces seizures, but other symptoms persist, providing the motivation for studying heptanoate metabolism. In this work, metabolism of infused [5,6,7-13C3]heptanoate was examined in the normal mouse brain and in G1D by 13C-nuclear magnetic resonance spectroscopy, gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS). In both groups, plasma glucose was enriched in 13C, confirming gluconeogenesis from heptanoate. Acetyl-CoA and glutamine levels became significantly higher in the brain of G1D mice relative to normal mice. In addition, brain glutamine concentration and 13C enrichment were also greater when compared with glutamate in both animal groups, suggesting that heptanoate and/or C5 ketones are primarily metabolized by glia. These results enlighten the mechanism of heptanoate metabolism in the normal and glucose-deficient brain and encourage further studies to elucidate its potential antiepileptic effects in disorders of energy metabolism. PMID:23072752

  6. Complications during intrahospital transport of critically ill patients: Focus on risk identification and prevention

    PubMed Central

    Knight, Patrick H; Maheshwari, Neelabh; Hussain, Jafar; Scholl, Michael; Hughes, Michael; Papadimos, Thomas J; Guo, Weidun Alan; Cipolla, James; Stawicki, Stanislaw P; Latchana, Nicholas

    2015-01-01

    Intrahospital transportation of critically ill patients is associated with significant complications. In order to reduce overall risk to the patient, such transports should well organized, efficient, and accompanied by the proper monitoring, equipment, and personnel. Protocols and guidelines for patient transfers should be utilized universally across all healthcare facilities. Care delivered during transport and at the site of diagnostic testing or procedure should be equivalent to the level of care provided in the originating environment. Here we review the most common problems encountered during transport in the hospital setting, including various associated adverse outcomes. Our objective is to make medical practitioners, nurses, and ancillary health care personnel more aware of the potential for various complications that may occur during patient movement from the intensive care unit to other locations within a healthcare facility, focusing on risk reduction and preventive strategies. PMID:26807395

  7. Electrokinetically-driven transport of DNA through focused ion beam milled nanofluidic channels.

    PubMed

    Menard, Laurent D; Ramsey, J Michael

    2013-01-15

    The electrophoretically driven transport of double-stranded λ-phage DNA through focused ion beam (FIB) milled nanochannels is described. Nanochannels were fabricated having critical dimensions (width and depth) corresponding to 0.5×, 1×, and 2× the DNA persistence length, or 25 nm, 50 nm, and 100 nm, respectively. The threshold field strength required to drive transport, the threading mobility, and the transport mobility were measured as a function of nanochannel size. As the nanochannel dimensions decreased, the entropic barrier to translocation increased and transport became more constrained. Equilibrium models of confinement provide a framework in which to understand the observed trends, although the dynamic nature of the experiments resulted in significant deviations from theory. It was also demonstrated that the use of dynamic wall coatings for the purpose of electroosmotic flow suppression can have a significant impact on transport dynamics that may obfuscate entropic contributions. The nonintermittent DNA transport through the FIB milled nanochannels demonstrates that they are well suited for use in nanofluidic devices. We expect that an understanding of the dynamic transport properties reported here will facilitate the incorporation of FIB-milled nanochannels in devices for single molecule and ensemble analyses.

  8. Making a semi-convex Focus area in a Focus+Glue+Context map, considering map visibility and transport access points

    NASA Astrophysics Data System (ADS)

    Hirako, Y.; Yamamoto, D.; Takahashi, N.

    2016-04-01

    We previously implemented the Focus+Glue+Context map system EMMA that provides local detailed data in Focus, global context data in Context, and connection data between both in the same view. Introducing the Glue area between Focus and Context makes it possible to provide uniform scaling for the two latter areas. This paper enhances EMMA through the implementation of a Focus creation function that considers transportation access points, such as stations and bus stops. The enhanced EMMA searches a route from the current location to the transportation access point, and allows users to identify the spatial relationship between the various locations in a small-scale Context, and view the route from the current location to the transportation access points in a large-scale Focus. However, if Focus is too large because of unnecessary areas used to identify the route, some parts of Context might be hidden by Focus. The proposed system solves this problem by implementing the following functions: (1) it searches stations that are adjacent to the current location and makes a semiconvex Focus that includes the current location and those stations in order for Focus to include really necessary areas. (2) It reduces Focus distortion by setting a fixed point as the center of the Focus area. (3) It smoothens the Focus shape in order to improve visibility in the Glue area. We developed a prototype of the proposed system that implements these functions.

  9. Neurotransmitters: The Critical Modulators Regulating Gut-Brain Axis.

    PubMed

    Mittal, Rahul; Debs, Luca H; Patel, Amit P; Nguyen, Desiree; Patel, Kunal; O'Connor, Gregory; Grati, M'hamed; Mittal, Jeenu; Yan, Denise; Eshraghi, Adrien A; Deo, Sapna K; Daunert, Sylvia; Liu, Xue Zhong

    2016-08-11

    Neurotransmitters including catecholamines and serotonin play a crucial role in maintaining homeostasis in the human body. Studies on these neurotransmitters mainly revolved around their role in the "fight or flight" response, transmitting signals across a chemical synapse and modulating blood flow throughout the body. However, recent research has demonstrated that neurotransmitters can play a significant role in the gastrointestinal (GI) physiology. Norepinephrine (NE), epinephrine (E), dopamine (DA), and serotonin have recently been a topic of interest because of their roles in the gut physiology and their potential roles in gastrointestinal and central nervous system pathophysiology. These neurotransmitters are able to regulate and control not only blood flow, but also affect gut motility, nutrient absorption, gastrointestinal innate immune system, and the microbiome. Furthermore, in pathological states such as inflammatory bowel disease (IBD) and Parkinson's disease, the levels of these neurotransmitters are dysregulated, therefore causing a variety of gastrointestinal symptoms. Research in this field has shown that exogenous manipulation of catecholamine serum concentrations can help in decreasing symptomology and/or disease progression. In this review article, we discuss the current state-of-the-art research and literature regarding the role of neurotransmitters in regulation of normal gastrointestinal physiology, their impact on several disease processes, and novel work focused on the use of exogenous hormones and/or psychotropic medications to improve disease symptomology. This article is protected by copyright. All rights reserved.

  10. Dynamic neurotransmitter interactions measured with PET

    SciTech Connect

    Schiffer, W.K.; Dewey, S.L.

    2001-04-02

    Positron emission tomography (PET) has become a valuable interdisciplinary tool for understanding physiological, biochemical and pharmacological functions at a molecular level in living humans, whether in a healthy or diseased state. The utility of tracing chemical activity through the body transcends the fields of cardiology, oncology, neurology and psychiatry. In this, PET techniques span radiochemistry and radiopharmaceutical development to instrumentation, image analysis, anatomy and modeling. PET has made substantial contributions in each of these fields by providing a,venue for mapping dynamic functions of healthy and unhealthy human anatomy. As diverse as the disciplines it bridges, PET has provided insight into an equally significant variety of psychiatric disorders. Using the unique quantitative ability of PET, researchers are now better able to non-invasively characterize normally occurring neurotransmitter interactions in the brain. With the knowledge that these interactions provide the fundamental basis for brain response, many investigators have recently focused their efforts on an examination of the communication between these chemicals in both healthy volunteers and individuals suffering from diseases classically defined as neurotransmitter specific in nature. In addition, PET can measure the biochemical dynamics of acute and sustained drug abuse. Thus, PET studies of neurotransmitter interactions enable investigators to describe a multitude of specific functional interactions in the human brain. This information can then be applied to understanding side effects that occur in response to acute and chronic drug therapy, and to designing new drugs that target multiple systems as opposed to single receptor types. Knowledge derived from PET studies can be applied to drug discovery, research and development (for review, see (Fowler et al., 1999) and (Burns et al., 1999)). Here, we will cover the most substantial contributions of PET to understanding

  11. Energy transport in plasmas produced by a high brightness krypton fluoride laser focused to a line

    SciTech Connect

    Al-Hadithi, Y.; Tallents, G.J. ); Zhang, J. ); Key, M.H.; Norreys, P.A.; Kodama, R. )

    1994-05-01

    A high brightness krypton fluoride Raman laser (wavelength 0.268 [mu]m) generating 0.3 TW, 12 ps pulses with 20 [mu]rad beam divergence and a prepulse of less than 10[sup [minus]10] has been focused to produce a 10 [mu]m wide line focus (irradiances [similar to]0.8--4[times]10[sup 15] W cm[sup [minus]2]) on plastic targets with a diagnostic sodium fluoride (NaF) layer buried within the target. Axial and lateral transport of energy has been measured by analysis of x-ray images of the line focus and from x-ray spectra emitted by the layer of NaF with varying overlay thicknesses. It is shown that the ratio of the distance between the critical density surface and the ablation surface to the laser focal width controls lateral transport in a similar manner as for previous spot focus experiments. The measured axial energy transport is compared to MEDUSA [J. P. Christiansen, D. E. T. F. Ashby, and K. V. Roberts, Comput. Phys. Commun. [bold 7], 271 (1974)] one-dimensional hydrodynamic code simulations with an average atom post-processor for predicting spectral line intensities. An energy absorption of [similar to]10% in the code gives agreement with the experimental axial penetration. Various measured line ratios of hydrogen- and helium-like Na and F are investigated as temperature diagnostics in the NaF layer using the RATION [R. W. Lee, B. L. Whitten, and R. E. Strout, J. Quant. Spectrosc. Radiat. Transfer [bold 32], 91 (1984)] code.

  12. Energy transport in plasmas produced by a high brightness krypton fluoride laser focused to a line

    NASA Astrophysics Data System (ADS)

    Al-Hadithi, Y.; Tallents, G. J.; Zhang, J.; Key, M. H.; Norreys, P. A.; Kodama, R.

    1994-05-01

    A high brightness krypton fluoride Raman laser (wavelength 0.268 μm) generating 0.3 TW, 12 ps pulses with 20 μrad beam divergence and a prepulse of less than 10-10 has been focused to produce a 10 μm wide line focus (irradiances ˜0.8-4×1015 W cm-2) on plastic targets with a diagnostic sodium fluoride (NaF) layer buried within the target. Axial and lateral transport of energy has been measured by analysis of x-ray images of the line focus and from x-ray spectra emitted by the layer of NaF with varying overlay thicknesses. It is shown that the ratio of the distance between the critical density surface and the ablation surface to the laser focal width controls lateral transport in a similar manner as for previous spot focus experiments. The measured axial energy transport is compared to medusa [J. P. Christiansen, D. E. T. F. Ashby, and K. V. Roberts, Comput. Phys. Commun. 7, 271 (1974)] one-dimensional hydrodynamic code simulations with an average atom post-processor for predicting spectral line intensities. An energy absorption of ˜10% in the code gives agreement with the experimental axial penetration. Various measured line ratios of hydrogen- and helium-like Na and F are investigated as temperature diagnostics in the NaF layer using the ration [R. W. Lee, B. L. Whitten, and R. E. Strout, J. Quant. Spectrosc. Radiat. Transfer 32, 91 (1984)] code.

  13. Time-coded neurotransmitter release at excitatory and inhibitory synapses

    PubMed Central

    Rodrigues, Serafim; Desroches, Mathieu; Krupa, Martin; Cortes, Jesus M.; Sejnowski, Terrence J.; Ali, Afia B.

    2016-01-01

    Communication between neurons at chemical synapses is regulated by hundreds of different proteins that control the release of neurotransmitter that is packaged in vesicles, transported to an active zone, and released when an input spike occurs. Neurotransmitter can also be released asynchronously, that is, after a delay following the spike, or spontaneously in the absence of a stimulus. The mechanisms underlying asynchronous and spontaneous neurotransmitter release remain elusive. Here, we describe a model of the exocytotic cycle of vesicles at excitatory and inhibitory synapses that accounts for all modes of vesicle release as well as short-term synaptic plasticity (STSP). For asynchronous release, the model predicts a delayed inertial protein unbinding associated with the SNARE complex assembly immediately after vesicle priming. Experiments are proposed to test the model’s molecular predictions for differential exocytosis. The simplicity of the model will also facilitate large-scale simulations of neural circuits. PMID:26858411

  14. Ion fluxes and neurotransmitters signaling in neural development.

    PubMed

    Andäng, Michael; Lendahl, Urban

    2008-06-01

    The brain develops and functions in a complex ionic milieu, which is a prerequisite for neurotransmitter function and neuronal signaling. Neurotransmitters and ion fluxes are, however, important not only in neuronal signaling, but also in the control of neural differentiation, and in this review, we highlight the recent advances in our understanding of how the gamma-amino butyric acid (GABA) neurotransmitter and ion fluxes are relevant for cell cycle control and neural differentiation. Conversely, proteins previously associated with ion transport across membranes have been endowed with novel ion-independent functions, and we discuss this in the context of gap junctions in cell adhesion and of the neuron-specific K(+)-Cl(-) cotransporter KCC2 in dendritic spine development. Collectively, these findings provide a richer and more complex picture of when ion fluxes are needed in neural development and when they are not.

  15. Neurotransmitters in the vestibular system.

    PubMed

    Balaban, C D

    2016-01-01

    Neuronal networks that are linked to the peripheral vestibular system contribute to gravitoinertial sensation, balance control, eye movement control, and autonomic function. Ascending connections to the limbic system and cerebral cortex are also important for motion perception and threat recognition, and play a role in comorbid balance and anxiety disorders. The vestibular system also shows remarkable plasticity, termed vestibular compensation. Activity in these networks is regulated by an interaction between: (1) intrinsic neurotransmitters of the inner ear, vestibular nerve, and vestibular nuclei; (2) neurotransmitters associated with thalamocortical and limbic pathways that receive projections originating in the vestibular nuclei; and (3) locus coeruleus and raphe (serotonergic and nonserotonergic) projections that influence the latter components. Because the ascending vestibular interoceptive and thalamocortical pathways include networks that influence a broad range of stress responses (endocrine and autonomic), memory consolidation, and cognitive functions, common transmitter substrates provide a basis for understanding features of acute and chronic vestibular disorders.

  16. Dynamics of laser-driven proton beam focusing and transport into solid density matter

    NASA Astrophysics Data System (ADS)

    Kim, J.; McGuffey, C.; Beg, F.; Wei, M.; Mariscal, D.; Chen, S.; Fuchs, J.

    2016-10-01

    Isochoric heating and local energy deposition capabilities make intense proton beams appealing for studying high energy density physics and the Fast Ignition of inertial confinement fusion. To study proton beam focusing that results in high beam density, experiments have been conducted using different target geometries irradiated by a kilojoule, 10 ps pulse of the OMEGA EP laser. The beam focus was measured by imaging beam-induced Cu K-alpha emission on a Cu foil that was positioned at a fixed distance. Compared to a free target, structured targets having shapes of wedge and cone show a brighter and narrower K-alpha radiation emission spot on a Cu foil indicating higher beam focusability. Experimentally observed images with proton radiography demonstrate the existence of transverse fields on the structures. Full-scale simulations including the contribution of a long pulse duration of the laser confirm that such fields can be caused by hot electrons moving through the structures. The simulated fields are strong enough to reflect the diverging main proton beam and pinch a transverse probe beam. Detailed simulation results including the beam focusing and transport of the focused intense proton beam in Cu foil will be presented. This work was supported by the National Laser User Facility Program through Award DE-NA0002034.

  17. Ferrographic tracking of bacterial transport in the field at the Narrow Channel focus area, Oyster, VA

    SciTech Connect

    Johnson, William P.; Zhang, Pengfei; Fuller, Mark E.; Scheibe, Timothy D. ); Mailloux, Brian J.; Onstott, Tullis C.; Deflaun, Mary F.; Hubbard, Susan; Radtke, Jon; Kovacic, William P.; Holben, William

    2001-01-01

    The first results from an innovative bacterial tracking technique, ferrographic capture, applied to bacterial transport in groundwater are reported in this paper. Ferrographic capture was used to analyze samples during an October 1999 bacterial injection experiment at the Narrow Channel Focus Area of the South Oyster Site, VA. Data obtained using this method showed that the timing of bacterial breakthrough was controlled by physical (hydraulic conductivity) heterogeneity in the vertical dimension, as opposed to variation in sediment surface or aqueous chemical properties. Ferrographic tracking yielded results that compared well with results from other tracking techniques over a concentration range of eight orders of magnitude, and provided a low detection limit relative to most other bacterial tracking techniques. The low detection limit of this method allowed observation of transport of an adhesion-deficient bacterium over distances greater than 20 m in the fine sand aquifer under lying this site.

  18. Interactions between Transporters and Herbal Medicines/Drugs: A Focus on Hepatoprotective Compounds.

    PubMed

    Zhang, Aijie; Li, Quansheng; He, Xin; Si, Duanyun; Liu, Changxiao

    2015-01-01

    Many herbal medicines and drugs are available in the clinic as potent hepatoprotective agents for the treatment of commonly occurring liver diseases. Recently, herbal medicines such as silymarin and curcumin have gained more attention and popularity for the treatment of various liver diseases because of their safety and efficacy profiles. Some of them are related to transporters for drug disposition processes, therapeutic efficacy and/or adverse drug reactions. Currently, herbal medicines and diet supplements made from natural products are widely used in patients who are being treated with conventional prescription medicines, which are related to an increasing risk of herbal-drug interactions (HDIs) and/or drug-drug interactions (DDIs). The purpose of present review is to summarize the contemporary knowledge of transporter-mediated HDIs or DDIs for herbal medicines/drugs focusing on hepatoprotective compounds. Several herbal medicines/drugs are discussed in detail in this review.

  19. Acceleration of low-energy ions at parallel shocks with a focused transport model

    SciTech Connect

    Zuo, Pingbing; Zhang, Ming; Rassoul, Hamid K.

    2013-03-19

    Here we present a test particle simulation on the injection and acceleration of low-energy suprathermal particles by parallel shocks with a focused transport model. The focused transport equation contains all necessary physics of shock acceleration, but avoids the limitation of diffusive shock acceleration (DSA) that requires a small pitch angle anisotropy. This simulation verifies that the particles with speeds of a fraction of to a few times the shock speed can indeed be directly injected and accelerated into the DSA regime by parallel shocks. At higher energies starting from a few times the shock speed, the energy spectrum of accelerated particles is a power law with the same spectral index as the solution of standard DSA theory, although the particles are highly anisotropic in the upstream region. The intensity, however, is different from that predicted by DSA theory, indicating a different level of injection efficiency. It is found that the shock strength, the injection speed, and the intensity of an electric cross-shock potential (CSP) jump can affect the injection efficiency of the low-energy particles. A stronger shock has a higher injection efficiency. In addition, if the speed of injected particles is above a few times the shock speed, the produced power-law spectrum is consistent with the prediction of standard DSA theory in both its intensity and spectrum index with an injection efficiency of 1. CSP can increase the injection efficiency through direct particle reflection back upstream, but it has little effect on the energetic particle acceleration once the speed of injected particles is beyond a few times the shock speed. Finally, this test particle simulation proves that the focused transport theory is an extension of DSA theory with the capability of predicting the efficiency of particle injection.

  20. Acceleration of low-energy ions at parallel shocks with a focused transport model

    DOE PAGES

    Zuo, Pingbing; Zhang, Ming; Rassoul, Hamid K.

    2013-03-19

    Here we present a test particle simulation on the injection and acceleration of low-energy suprathermal particles by parallel shocks with a focused transport model. The focused transport equation contains all necessary physics of shock acceleration, but avoids the limitation of diffusive shock acceleration (DSA) that requires a small pitch angle anisotropy. This simulation verifies that the particles with speeds of a fraction of to a few times the shock speed can indeed be directly injected and accelerated into the DSA regime by parallel shocks. At higher energies starting from a few times the shock speed, the energy spectrum of acceleratedmore » particles is a power law with the same spectral index as the solution of standard DSA theory, although the particles are highly anisotropic in the upstream region. The intensity, however, is different from that predicted by DSA theory, indicating a different level of injection efficiency. It is found that the shock strength, the injection speed, and the intensity of an electric cross-shock potential (CSP) jump can affect the injection efficiency of the low-energy particles. A stronger shock has a higher injection efficiency. In addition, if the speed of injected particles is above a few times the shock speed, the produced power-law spectrum is consistent with the prediction of standard DSA theory in both its intensity and spectrum index with an injection efficiency of 1. CSP can increase the injection efficiency through direct particle reflection back upstream, but it has little effect on the energetic particle acceleration once the speed of injected particles is beyond a few times the shock speed. Finally, this test particle simulation proves that the focused transport theory is an extension of DSA theory with the capability of predicting the efficiency of particle injection.« less

  1. Absorption of vitamin A and carotenoids by the enterocyte: focus on transport proteins.

    PubMed

    Reboul, Emmanuelle

    2013-09-12

    Vitamin A deficiency is a public health problem in most developing countries, especially in children and pregnant women. It is thus a priority in health policy to improve preformed vitamin A and/or provitamin A carotenoid status in these individuals. A more accurate understanding of the molecular mechanisms of intestinal vitamin A absorption is a key step in this direction. It was long thought that β-carotene (the main provitamin A carotenoid in human diet), and thus all carotenoids, were absorbed by a passive diffusion process, and that preformed vitamin A (retinol) absorption occurred via an unidentified energy-dependent transporter. The discovery of proteins able to facilitate carotenoid uptake and secretion by the enterocyte during the past decade has challenged established assumptions, and the elucidation of the mechanisms of retinol intestinal absorption is in progress. After an overview of vitamin A and carotenoid fate during gastro-duodenal digestion, our focus will be directed to the putative or identified proteins participating in the intestinal membrane and cellular transport of vitamin A and carotenoids across the enterocyte (i.e., Scavenger Receptors or Cellular Retinol Binding Proteins, among others). Further progress in the identification of the proteins involved in intestinal transport of vitamin A and carotenoids across the enterocyte is of major importance for optimizing their bioavailability.

  2. Vitamin transport and homeostasis in mammalian brain: focus on Vitamins B and E.

    PubMed

    Spector, Reynold; Johanson, Conrad E

    2007-10-01

    With the application of genetic and molecular biology techniques, there has been substantial progress in understanding how vitamins are transferred across the mammalian blood-brain barrier and choroid plexus into brain and CSF and how vitamin homeostasis in brain is achieved. In most cases (with the exception of the sodium-dependent multivitamin transporter for biotin, pantothenic acid, and lipoic acid), the vitamins are transported by separate carriers through the blood-brain barrier or choroid plexus. Then the vitamins are accumulated by brain cells by separate, specialized systems. This review focuses on six vitamins (B(1), B(3), B(6), pantothenic acid, biotin, and E) and the newer genetic information including relevant 'knockdown' or 'knockout' models in mice and humans. The overall objective is to integrate this newer information with previous physiological and biochemical observations to achieve a better understanding of vitamin transport and homeostasis in brain. This is especially important in view of the newly described non-cofactor vitamin roles in brain (e.g. of B(1), B(3), B(6), and E) and the potential roles of vitamins in the therapy of brain disorders.

  3. Absorption of Vitamin A and Carotenoids by the Enterocyte: Focus on Transport Proteins

    PubMed Central

    Reboul, Emmanuelle

    2013-01-01

    Vitamin A deficiency is a public health problem in most developing countries, especially in children and pregnant women. It is thus a priority in health policy to improve preformed vitamin A and/or provitamin A carotenoid status in these individuals. A more accurate understanding of the molecular mechanisms of intestinal vitamin A absorption is a key step in this direction. It was long thought that β-carotene (the main provitamin A carotenoid in human diet), and thus all carotenoids, were absorbed by a passive diffusion process, and that preformed vitamin A (retinol) absorption occurred via an unidentified energy-dependent transporter. The discovery of proteins able to facilitate carotenoid uptake and secretion by the enterocyte during the past decade has challenged established assumptions, and the elucidation of the mechanisms of retinol intestinal absorption is in progress. After an overview of vitamin A and carotenoid fate during gastro-duodenal digestion, our focus will be directed to the putative or identified proteins participating in the intestinal membrane and cellular transport of vitamin A and carotenoids across the enterocyte (i.e., Scavenger Receptors or Cellular Retinol Binding Proteins, among others). Further progress in the identification of the proteins involved in intestinal transport of vitamin A and carotenoids across the enterocyte is of major importance for optimizing their bioavailability. PMID:24036530

  4. Design of a superconducting beam transport channel and beam dynamics for a strong-focusing cyclotron

    NASA Astrophysics Data System (ADS)

    Badgley, Karie Elizabeth

    There is an increasing interest in high power proton accelerators for use as neutron and muon sources, accelerator driven systems (ADS) for nuclear waste transmutation, high energy physics, medical physics, nuclear physics, and medical isotope production. Accelerating high current beams has a number of challenges; including avoiding harmful resonance crossing, space charge effects and, specific to cyclotrons, sufficient turn separation at injection and extraction. The Accelerator Research Laboratory at Texas A&M University is developing a high-power strong-focusing cyclotron with two main technologies to overcome these challenges. The first is a superconducting RF cavity to provide the energy gain required for fully separated turns. The second is the use of superconducting beam transport channels within the sectors of the cyclotron to provide strong-focusing with alternating focusing and defocusing quadrupoles. A method has been developed to find the equilibrium spiral orbit through the cyclotron which maintains isochronicity. The isochronous spiral orbit was then used to perform full linear optics calculations. The strengths of the quadrupoles were adjusted to hold the horizontal and vertical betatron tunes constant per turn to avoid resonance crossing. Particle tracking was performed with a modified MAD-X-PTC code and Synergia to provide a framework for future space charge studies. Magnetic modeling was performed on a 2D cross section of the beam transport channel. The wire locations were adjusted to reduce the higher order multipoles and a good field region was obtained at 70% of the beam pipe aperture with multipoles less than 10-4 . The 2D model was also used to determine the required current density needed to produce the quadrupole gradients. MgB2 superconducting wire was chosen as it meets all the field and current requirements and can operate at a reduced cryogenic cost. A winding mandrel was also designed and fabricated which minimized the bend radius for

  5. Neurotransmitters, psychotropic drugs and microglia: clinical implications for psychiatry.

    PubMed

    Kato, T A; Yamauchi, Y; Horikawa, H; Monji, A; Mizoguchi, Y; Seki, Y; Hayakawa, K; Utsumi, H; Kanba, S

    2013-01-01

    Psychiatric disorders have long and dominantly been regarded to be induced by disturbances of neuronal networks including synapses and neurotransmitters. Thus, the effects of psychotropic drugs such as antipsychotics and antidepressants have been understood to modulate synaptic regulation via receptors and transporters of neurotransmitters such as dopamine and serotonin. Recently, microglia, immunological/inflammatory cells in the brain, have been indicated to have positive links to psychiatric disorders. Positron emission tomography (PET) imaging and postmortem studies have revealed microglial activation in the brain of neuropsychiatric disorders such as schizophrenia, depression and autism. Animal models of neuropsychiatric disorders have revealed the underlying microglial pathologies. In addition, various psychotropic drugs have been suggested to have direct effects on microglia. Until now, the relationship between microglia, neurotransmitters and psychiatric disorders has not been well understood. Therefore, in this review, at first, we summarize recent findings of interaction between microglia and neurotransmitters such as dopamine, serotonin, norepinephrine, acetylcholine and glutamate. Next, we introduce up-to-date knowledge of the effects of psychotropic drugs such as antipsychotics, antidepressants and antiepileptics on microglial modulation. Finally, we propose the possibility that modulating microglia may be a key target in the treatment of various psychiatric disorders. Further investigations and clinical trials should be conducted to clarify this perspective, using animal in vivo studies and imaging studies with human subjects.

  6. Volatiles beneath mid-ocean ridges: Deep melting, channelised transport, focusing, and metasomatism

    NASA Astrophysics Data System (ADS)

    Keller, Tobias; Katz, Richard F.; Hirschmann, Marc M.

    2017-04-01

    Deep-Earth volatile cycles couple the mantle with near-surface reservoirs. Volatiles are emitted by volcanism and, in particular, from mid-ocean ridges, which are the most prolific source of basaltic volcanism. Estimates of volatile extraction from the asthenosphere beneath ridges typically rely on measurements of undegassed lavas combined with simple petrogenetic models of the mean degree of melting. Estimated volatile fluxes have large uncertainties; this is partly due to a poor understanding of how volatiles are transported by magma in the asthenosphere. Here, we assess the fate of mantle volatiles through numerical simulations of melting and melt transport at mid-ocean ridges. Our simulations are based on two-phase, magma/mantle dynamics theory coupled to an idealised thermodynamic model of mantle melting in the presence of water and carbon dioxide. We combine simulation results with catalogued observations of all ridge segments to estimate a range of likely volatile output from the global mid-ocean ridge system. We thus predict global MOR crust production of 66-73 Gt/yr (22-24 km3/yr) and global volatile output of 52-110 Mt/yr, corresponding to mantle volatile contents of 100-200 ppm. We find that volatile extraction is limited: up to half of deep, volatile-rich melt is not focused to the axis but is rather deposited along the LAB. As these distal melts crystallise and fractionate, they metasomatise the base of the lithosphere, creating rheological heterogeneity that could contribute to the seismic signature of the LAB.

  7. Quadrupole Strong Focusing for Transport of Space-Charge Dominated Electron Beams in Traveling-Wave Tubes

    NASA Astrophysics Data System (ADS)

    Nichols, Kimberley E. L.

    Analysis of quadrupole focusing lattices for high-frequency TWT's is presented. This work is motivated by recent work performed at the Naval Research Laboratory (NRL) which demonstrated an advantageous case for strong focusing employing a Halbach quadrupole lattice. Using realistic Permanent Magnet Quadruple (PMQ) field cancellation, the advantage of using PMQ to transport higher current densities than Permanent Periodic Magnet (PPM) lattices disappears, while other advantages for employing quadrupole focusing remain. This dissertation gives a comprehensive analysis of the applicability of PMQ focusing in vacuum electronic devices.

  8. Investigation of Generation, Acceleration, Transport and Final Focusing of High-Intensity Heavy Ion Beams from Sources to Targets

    SciTech Connect

    Chiping Chen

    2006-10-26

    Under the auspices of the research grant, the Intense Beam Theoretical Research Goup at Massachusetts Institute of Technology's Plasma Science and Fusion Center made significant contributions in a number of important areas in the HIF and HEDP research, including: (a) Derivation of rms envelope equations and study of rms envelope dynamics for high-intensity heavy ion beams in a small-aperture AG focusing transport systems; (b) Identification of a new mechanism for chaotic particle motion, halo formation, and beam loss in high-intensity heavy ion beams in a small-aperture AG focusing systems; Development of elliptic beam theory; (d) Study of Physics Issues in the Neutralization Transport Experiment (NTX).

  9. Amino acid neurotransmitters in the retina: a functional overview.

    PubMed

    Wu, S M; Maple, B R

    1998-05-01

    Physiological and pharmacological mechanisms of glutamatergic, GABAergic and glycinergic synapses in the tiger salamander retina were studied. We used immunocytochemical and autoradiographic methods to study localizations of these neurotransmitters and their uptake transporters; and electrophysiological methods (intracellular, extracellular and whole cell patch electrode recordings) to study the light responses, miniature postsynaptic currents and neurotransmitter-induced postsynaptic currents in various retinal neurons. Our results are consistent with the following scheme: Glutamate is used by the photoreceptor and bipolar cell output synapses and the release of glutamate is largely mediated by calcium-dependent vesicular processes. The postsynaptic glutamate receptors in DBCs are L-AP4 receptors, in HBCs, HCs and ganglion cells are the kainate/AMPA and NMDA receptors. Subpopulations of HCs make GABAergic synapses on cones and gate chloride condunctance through GABAA receptors. GABAergic HCs do not make feedforward synapses on bipolar cell dendrites and the neurotransmitter identity of the HCs making feedforward synapses is unknown. Subpopulations of amacrine cells make GABAergic synapses on bipolar cell synaptic terminals, other amacrine cells and ganglion cells and GABA gates chloride conductances in theses cells. Glycinergic amacrine cells make synapses on bipolar cell synaptic terminals, other amacrine cells and ganglion cells and glycine opens postsynaptic chloride channels. Glycinergic interplexiform cells make synapses on bipolar cells in the outer retina and glycine released from these cells open chloride channels in bipolar cell dendrites.

  10. Microfabricated device and method for multiplexed electrokinetic focusing of fluid streams and a transport cytometry method using same

    DOEpatents

    Jacobson, Stephen C.; Ramsey, J. Michael

    2000-01-01

    A microfabricated device and method for electrokinetic transport of a liquid phase biological or chemical material is described. In accordance with one aspect of the present invention there is provided a microchip that is adapted for the simultaneous spatial confinement of electrokinetically driven fluidic material streams on a substrate. The apparatus includes a focusing chamber formed in a surface of the substrate and in fluid communication with two sample fluid channels and three focusing fluid channels. The device further includes electromotive means operatively connected to the sources of the sample fluid and the source of focusing fluid for electrokinetically driving the respective streams of the sample and focusing fluids through the respective channels into the focusing chamber such that the focusing fluid streams spatially confine the first and second sample fluid streams within the focusing chamber. In accordance with another aspect of this invention, there is provided a cytometry method for analyzing microscopic particles in a fluid medium on a microchip by utilizing the focusing function of the microchip. In the disclosed cytometry process the width of the fluid stream is narrowed in the focusing chamber. The microscopic particles in the focused sample fluid are then detected and/or measured using light scattering or other techniques.

  11. Scaling approach to tight-binding transport in realistic graphene devices: The case of transverse magnetic focusing

    NASA Astrophysics Data System (ADS)

    Beconcini, M.; Valentini, S.; Kumar, R. Krishna; Auton, G. H.; Geim, A. K.; Ponomarenko, L. A.; Polini, M.; Taddei, F.

    2016-09-01

    Ultraclean graphene sheets encapsulated between hexagonal boron nitride crystals host two-dimensional electron systems in which low-temperature transport is solely limited by the sample size. We revisit the theoretical problem of carrying out microscopic calculations of nonlocal ballistic transport in such micron-scale devices. By employing the Landauer-Büttiker scattering theory, we propose a scaling approach to tight-binding nonlocal transport in realistic graphene devices. We test our numerical method against experimental data on transverse magnetic focusing (TMF), a textbook example of nonlocal ballistic transport in the presence of a transverse magnetic field. This comparison enables a clear physical interpretation of all the observed features of the TMF signal, including its oscillating sign.

  12. Microtubule-stabilizing peptides and small molecules protecting axonal transport and brain function: focus on davunetide (NAP).

    PubMed

    Magen, Iddo; Gozes, Illana

    2013-12-01

    This review focuses on the therapeutic effects and mechanisms of action of NAP (davunetide), an eight amino acid snippet derived from activity-dependent neuroprotective protein (ADNP) which was discovered in our laboratory. We have recently described the effects of NAP in neurodegenerative disorders, and we now review the beneficial effects of NAP and other microtubule-stabilizing agents on impairments in axonal transport. Experiments in animal models of microtubule-deficiency including tauopathy (spanning from drosophila to mammals) showed protection of axonal transport by microtubule-stabilizers and NAP, which was coupled to motor and cognitive protection. Clinical trials with NAP (davunetide) are reviewed paving the path to future developments.

  13. Mapping neurotransmitter networks with PET: an example on serotonin and opioid systems.

    PubMed

    Tuominen, Lauri; Nummenmaa, Lauri; Keltikangas-Järvinen, Liisa; Raitakari, Olli; Hietala, Jarmo

    2014-05-01

    All functions of the human brain are consequences of altered activity of specific neural pathways and neurotransmitter systems. Although the knowledge of "system level" connectivity in the brain is increasing rapidly, we lack "molecular level" information on brain networks and connectivity patterns. We introduce novel voxel-based positron emission tomography (PET) methods for studying internal neurotransmitter network structure and intercorrelations of different neurotransmitter systems in the human brain. We chose serotonin transporter and μ-opioid receptor for this analysis because of their functional interaction at the cellular level and similar regional distribution in the brain. Twenty-one healthy subjects underwent two consecutive PET scans using [(11)C]MADAM, a serotonin transporter tracer, and [(11)C]carfentanil, a μ-opioid receptor tracer. First, voxel-by-voxel "intracorrelations" (hub and seed analyses) were used to study the internal structure of opioid and serotonin systems. Second, voxel-level opioid-serotonin intercorrelations (between neurotransmitters) were computed. Regional μ-opioid receptor binding potentials were uniformly correlated throughout the brain. However, our analyses revealed nonuniformity in the serotonin transporter intracorrelations and identified a highly connected local network (midbrain-striatum-thalamus-amygdala). Regionally specific intercorrelations between the opioid and serotonin tracers were found in anteromedial thalamus, amygdala, anterior cingulate cortex, dorsolateral prefrontal cortex, and left parietal cortex, i.e., in areas relevant for several neuropsychiatric disorders, especially affective disorders. This methodology enables in vivo mapping of connectivity patterns within and between neurotransmitter systems. Quantification of functional neurotransmitter balances may be a useful approach in etiological studies of neuropsychiatric disorders and also in drug development as a biomarker-based rationale for targeted

  14. LeuT-Desipramine Structure Reveals How Antidepressants Block Neurotransmitter Reuptake

    SciTech Connect

    Zhou,Z.; Zhen, J.; Karpowich, N.; Goetz, R.; Law, C.; Reith, M.; Wang, D.

    2007-01-01

    Tricyclic antidepressants exert their pharmacological effect -- inhibiting the reuptake of serotonin, norepinephrine, and dopamine -- by directly blocking neurotransmitter transporters (SERT, NET, and DAT, respectively) in the presynaptic membrane. The drug-binding site and the mechanism of this inhibition are poorly understood. We determined the crystal structure at 2.9 angstroms of the bacterial leucine transporter (LeuT), a homolog of SERT, NET, and DAT, in complex with leucine and the antidepressant desipramine. Desipramine binds at the inner end of the extracellular cavity of the transporter and is held in place by a hairpin loop and by a salt bridge. This binding site is separated from the leucine-binding site by the extracellular gate of the transporter. By directly locking the gate, desipramine prevents conformational changes and blocks substrate transport. Mutagenesis experiments on human SERT and DAT indicate that both the desipramine-binding site and its inhibition mechanism are probably conserved in the human neurotransmitter transporters.

  15. LeuT-desipramine structure reveals how antidepressants block neurotransmitter reuptake.

    PubMed

    Zhou, Zheng; Zhen, Juan; Karpowich, Nathan K; Goetz, Regina M; Law, Christopher J; Reith, Maarten E A; Wang, Da-Neng

    2007-09-07

    Tricyclic antidepressants exert their pharmacological effect-inhibiting the reuptake of serotonin, norepinephrine, and dopamine-by directly blocking neurotransmitter transporters (SERT, NET, and DAT, respectively) in the presynaptic membrane. The drug-binding site and the mechanism of this inhibition are poorly understood. We determined the crystal structure at 2.9 angstroms of the bacterial leucine transporter (LeuT), a homolog of SERT, NET, and DAT, in complex with leucine and the antidepressant desipramine. Desipramine binds at the inner end of the extracellular cavity of the transporter and is held in place by a hairpin loop and by a salt bridge. This binding site is separated from the leucine-binding site by the extracellular gate of the transporter. By directly locking the gate, desipramine prevents conformational changes and blocks substrate transport. Mutagenesis experiments on human SERT and DAT indicate that both the desipramine-binding site and its inhibition mechanism are probably conserved in the human neurotransmitter transporters.

  16. The role of cross-shock potential on pickup ion shock acceleration in the framework of focused transport theory

    DOE PAGES

    Zuo, Pingbing; Zhang, Ming; Rassoul, Hamid K.

    2013-10-03

    The focused transport theory is appropriate to describe the injection and acceleration of low-energy particles at shocks as an extension of diffusive shock acceleration (DSA). In this investigation, we aim to characterize the role of cross-shock potential (CSP) originated in the charge separation across the shock ramp on pickup ion (PUI) acceleration at various types of shocks with a focused transport model. The simulation results of energy spectrum and spatial density distribution for the cases with and without CSP added in the model are compared. With sufficient acceleration time, the focused transport acceleration finally falls into the DSA regime withmore » the power-law spectral index equal to the solution of the DSA theory. The CSP can affect the shape of the spectrum segment at lower energies, but it does not change the spectral index of the final power-law spectrum at high energies. It is found that the CSP controls the injection efficiency which is the fraction of PUIs reaching the DSA regime. A stronger CSP jump results in a dramatically improved injection efficiency. Our simulation results also show that the injection efficiency of PUIs is mass-dependent, which is lower for species with a higher mass. Additionally, the CSP is able to enhance the particle reflection upstream to produce a stronger intensity spike at the shock front. Lastly, we conclude that the CSP is a non-negligible factor that affects the dynamics of PUIs at shocks.« less

  17. Neurotransmitter properties of the newborn human retina

    SciTech Connect

    Hollyfield, J.G.; Frederick, J.M.; Rayborn, M.E.

    1983-07-01

    Human retinal tissue from a newborn was examined autoradiographically for the presence of high-affinity uptake and localization of the following putative neurotransmitters: dopamine, glycine, GABA, aspartate, and glutamate. In addition, the dopamine content of this newborn retina was measured by high pressure liquid chromatography. Our study reveals that specific uptake mechanisms for /sup 3/H-glycine, /sup 3/H-dopamine, and /sup 3/H-GABA are present at birth. However, the number and distribution of cells labeled with each of these /sup 3/H-transmitters are not identical to those observed in adult human retinas. Furthermore, the amount of endogenous dopamine in the newborn retina is approximately 1/20 the adult level. Photoreceptor-specific uptake of /sup 3/H-glutamate and /sup 3/H-aspartate are not observed. These findings indicate that, while some neurotransmitter-specific properties are present at birth, significant maturation of neurotransmitter systems occurs postnatally.

  18. Regulation of neurotransmitter release kinetics by NSF.

    PubMed

    Schweizer, F E; Dresbach, T; DeBello, W M; O'Connor, V; Augustine, G J; Betz, H

    1998-02-20

    NSF (N-ethylmaleimide-sensitive factor) is an adenosine triphosphatase (ATPase) that contributes to a protein complex essential for membrane fusion. The synaptic function of this protein was investigated by injecting, into the giant presynaptic terminal of squid, peptides that inhibit the ATPase activity of NSF stimulated by the soluble NSF attachment protein (SNAP). These peptides reduced the amount and slowed the kinetics of neurotransmitter release as a result of actions that required vesicle turnover and occurred at a step subsequent to vesicle docking. These results define NSF as an essential participant in synaptic vesicle exocytosis that regulates the kinetics of neurotransmitter release and, thereby, the integrative properties of synapses.

  19. Out-of-focus effects on microscale schlieren measurements of mass transport in a microfluidic device

    NASA Astrophysics Data System (ADS)

    Chen, Shao-Tuan; Sun, Chen-li

    2016-08-01

    The microscale schlieren technique provides a means for a non-invasive, full-field measurement for mixing microfluidics with excellent sensitivity and resolution. Nevertheless, an out-of-focus effect due to microscopic optics may lead to undesirable errors in quantifying the gradient information at high degrees of magnification. If the channel in the microfluidic device under study is too deep, light deflection caused by inhomogeneity located far from the focal plane may contributes little to the intensity change on the image plane. To address this issue, we propose the use of a weighting function that approximates a Gaussian profile with an optical-system-dependable width. We assume that the resultant intensity change is proportional to a weighted sum of the gradient across the channel depth and acquire micro-schlieren images of fluid mixing in a T-junction microchannel at various positions along the optical axis. For each objective, the width of the weighting function is then determined iteratively by curve fitting the ratio of changes in grayscale readouts for out-of-focus and focus micro-schlieren images. The standard deviation in the Gaussian distribution facilitates the quantification of the out-of-focus effect. In addition, we measure the sensitivities of a microscale schlieren system equipped with different objectives and compare the values to the model. Despite its better resolution, we find that an objective with higher magnification suffers from a more severe out-of-focus effect and a loss of sensitivity. Equations are proposed for estimations of the standard deviation and the sensitivity of microscale schlieren measurements. The outcome will facilitate the selection of proper microchannel depths for various microscale schlieren systems or vice versa, thus improving the precision of micro-schlieren measurements in microfluidic devices.

  20. COSMIC RAY TRANSPORT WITH MAGNETIC FOCUSING AND THE “TELEGRAPH” MODEL

    SciTech Connect

    Malkov, M. A.; Sagdeev, R. Z.

    2015-08-01

    Cosmic rays (CR), constrained by scattering on magnetic irregularities, are believed to propagate diffusively. However, a well-known defect of diffusive approximation, whereby some of the particles propagate unrealistically fast, has directed interest toward an alternative CR transport model based on the “telegraph” equation. Though, its derivations often lack rigor and transparency leading to inconsistent results. We apply the classic Chapman–Enskog method to the CR transport problem. We show that no “telegraph” (second order time derivative) term emerges in any order of a proper asymptotic expansion with systematically eliminated short timescales. Nevertheless, this term may formally be converted from the fourth order hyper-diffusive term of the expansion. However, both the telegraph and hyperdiffusive terms may only be important for a short relaxation period associated with either strong pitch-angle anisotropy or spatial inhomogeneity of the initial CR distribution. Beyond this period the system evolves diffusively in both cases. The term conversion, that makes the telegraph and Chapman–Enskog approaches reasonably equivalent, is possible only after this relaxation period. During this period, the telegraph solution is argued to be unphysical. Unlike the hyperdiffusion correction, it is not uniformly valid and introduces implausible singular components to the solution. These dominate the solution during the relaxation period. Because they are shown not to be inherent in the underlying scattering problem, we argue that the telegraph term is involuntarily acquired in an asymptotic reduction of the problem.

  1. Epigenetic regulation of ADME-related genes: focus on drug metabolism and transport.

    PubMed

    Zhong, Xiao-bo; Leeder, J Steven

    2013-10-01

    Epigenetic regulation of gene expression refers to heritable factors that are functionally relevant genomic modifications but that do not involve changes in DNA sequence. Examples of such modifications include DNA methylation, histone modifications, noncoding RNAs, and chromatin architecture. Epigenetic modifications are crucial for packaging and interpreting the genome, and they have fundamental functions in regulating gene expression and activity under the influence of physiologic and environmental factors. Recently, epigenetics has become one of the fastest-growing areas of science and has now become a central issue in biologic studies of development and disease pathogenesis. The interest in epigenetics is also true for studies of drug metabolism and transport. In this issue of Drug Metabolism and Disposition, a series of articles is presented to demonstrate the role of epigenetic factors in regulating the expression of genes involved in drug absorption, distribution, metabolism, and excretion in organ development, tissue-specific gene expression, sexual dimorphism, and in the adaptive response to xenobiotic exposure, both therapeutic and toxic. The articles also demonstrate that, in addition to genetic polymorphisms, epigenetics may also contribute to wide interindividual variations in drug metabolism and transport. Identification of functionally relevant epigenetic biomarkers in human specimens has the potential to improve prediction of drug responses based on patient's epigenetic profiles.

  2. Survey of Genes Involved in Biosynthesis, Transport, and Signaling of Phytohormones with Focus on Solanum lycopersicum

    PubMed Central

    Simm, Stefan; Scharf, Klaus-Dieter; Jegadeesan, Sridharan; Chiusano, Maria Luisa; Firon, Nurit; Schleiff, Enrico

    2016-01-01

    Phytohormones control the development and growth of plants, as well as their response to biotic and abiotic stress. The seven most well-studied phytohormone classes defined today are as follows: auxins, ethylene, cytokinin, abscisic acid, jasmonic acid, gibberellins, and brassinosteroids. The basic principle of hormone regulation is conserved in all plants, but recent results suggest adaptations of synthesis, transport, or signaling pathways to the architecture and growth environment of different plant species. Thus, we aimed to define the extent to which information from the model plant Arabidopsis thaliana is transferable to other plants such as Solanum lycopersicum. We extracted the co-orthologues of genes coding for major pathway enzymes in A. thaliana from the translated genomes of 12 species from the clade Viridiplantae. Based on predicted domain architecture and localization of the identified proteins from all 13 species, we inspected the conservation of phytohormone pathways. The comparison was complemented by expression analysis of (co-) orthologous genes in S. lycopersicum. Altogether, this information allowed the assignment of putative functional equivalents between A. thaliana and S. lycopersicum but also pointed to some variations between the pathways in eudicots, monocots, mosses, and green algae. These results provide first insights into the conservation of the various phytohormone pathways between the model system A. thaliana and crop plants such as tomato. We conclude that orthologue prediction in combination with analysis of functional domain architecture and intracellular localization and expression studies are sufficient tools to transfer information from model plants to other plant species. Our results support the notion that hormone synthesis, transport, and response for most part of the pathways are conserved, and species-specific variations can be found. PMID:27695302

  3. Detection and Quantification of Neurotransmitters in Dialysates

    PubMed Central

    Zapata, Agustin; Chefer, Vladimir I.; Shippenberg, Toni S.; Denoroy, Luc

    2010-01-01

    Sensitive analytical methods are needed for the separation and quantification of neurotransmitters obtained in microdialysate studies. This unit describes methods that permit quantification of nanomolar concentrations of monoamines and their metabolites (high-pressure liquid chromatography electrochemical detection), acetylcholine (HPLC-coupled to an enzyme reactor), and amino acids (HPLC-fluorescence detection; capillary electrophoresis with laser-induced fluorescence detection). PMID:19575473

  4. Chemical delivery array with millisecond neurotransmitter release

    PubMed Central

    Jonsson, Amanda; Sjöström, Theresia Arbring; Tybrandt, Klas; Berggren, Magnus; Simon, Daniel T.

    2016-01-01

    Technologies that restore or augment dysfunctional neural signaling represent a promising route to deeper understanding and new therapies for neurological disorders. Because of the chemical specificity and subsecond signaling of the nervous system, these technologies should be able to release specific neurotransmitters at specific locations with millisecond resolution. We have previously demonstrated an organic electronic lateral electrophoresis technology capable of precise delivery of charged compounds, such as neurotransmitters. However, this technology, the organic electronic ion pump, has been limited to a single delivery point, or several simultaneously addressed outlets, with switch-on speeds of seconds. We report on a vertical neurotransmitter delivery device, configured as an array with individually controlled delivery points and a temporal resolution of 50 ms. This is achieved by supplementing lateral electrophoresis with a control electrode and an ion diode at each delivery point to allow addressing and limit leakage. By delivering local pulses of neurotransmitters with spatiotemporal dynamics approaching synaptic function, the high-speed delivery array promises unprecedented access to neural signaling and a path toward biochemically regulated neural prostheses. PMID:27847873

  5. Mechanisms of glutamate transport.

    PubMed

    Vandenberg, Robert J; Ryan, Renae M

    2013-10-01

    L-Glutamate is the predominant excitatory neurotransmitter in the mammalian central nervous system and plays important roles in a wide variety of brain functions, but it is also a key player in the pathogenesis of many neurological disorders. The control of glutamate concentrations is critical to the normal functioning of the central nervous system, and in this review we discuss how glutamate transporters regulate glutamate concentrations to maintain dynamic signaling mechanisms between neurons. In 2004, the crystal structure of a prokaryotic homolog of the mammalian glutamate transporter family of proteins was crystallized and its structure determined. This has paved the way for a better understanding of the structural basis for glutamate transporter function. In this review we provide a broad perspective of this field of research, but focus primarily on the more recent studies with a particular emphasis on how our understanding of the structure of glutamate transporters has generated new insights.

  6. Simulation of Electron Beam Transport in Ion-Focused Regime Conditioning Cells

    DTIC Science & Technology

    1992-07-21

    leflhron Davis lgharay. Swft, I M. Arlington. VA 22Z02.4302. and to the office of Management and Budget. Paperwork Reduction Protect (07044 1in). Wahngon...nb(r, rz) and nh(r, rz) are the beam and ion densities, respectively, and vi is the gas ionization rate. In sir at pressure P, vi =P(torr) nsecŕ . In... Humphries and Ekdah156 and Fernsler, et al.57 FRIEZR employs a variation of Adler’s thin lens approximation to treat foil focusing. The impulse has the

  7. Intense electron-beam transport in the ion-focused regime through the collision-dominated regime

    SciTech Connect

    Sanford, T.W.L.; Poukey, J.W.; Welch, D.R.; Mock, R.C.

    1993-12-31

    This paper reviews the transport of the 19-MeV, 700-kA, 25-ns Hermes-III electron beam in long gas cells filled with N{sub 2} gas spanning six decades in pressure from 10{sup 3} to {approximately}10{sup 3} Torr. We show through measurements and theoretical analyses that the beam has two windows of stable transport: a low-pressure window (between {approximately}1 and {approximately}100 mTorr) that is dominated by propagation in the semi-collisionless IFR (ion-focused regime), and a high-pressure window (between {approximately}1 and {approximately}100 Torr) that is dominated by propagation in the resistive CDR (collision-dominated regime). In the CDR, 79{plus_minus}1.5% of the beam energy is transported over 11 m at 20 Torr. In the IFR, we show that intense radiation fields with controllable rise times and pulse widths can be generated on axis at a bremsstrahlung target. In summary, the measurements and analyses presented here provide a quantitative description of the Hermes-III beam transport over six decades in pressure.

  8. Atypical Neurotransmitters and the Neurobiology of Depression.

    PubMed

    Joca, Samia Regiane; Moreira, Fabricio Araujo; Wegener, Gregers

    2015-01-01

    Since the first report that the mechanism of action of antidepressants involves the facilitation of monoaminergic neurotransmission in the brain in the 1960s, the leading hypothesis about the neurobiology of depression has been the so called "monoaminergic hypothesis". However, a growing body of evidence from the last two decades also supports important involvement of non-monoaminergic mechanisms in the neurobiology of depression and antidepressant action. The discovery of nitric oxide (NO) and endocannabinoid signaling in the brain during the 1990s challenged the wellestablished criteria of classical neurotransmission. These transmitters are synthesized and released on demand by the postsynaptic neurons, and may act as a retrograde messenger on the presynaptic terminal, modulating neurotransmitter release. These unconventional signaling mechanisms and the important role as neural messengers have classified NO and endocannabinoids as atypical neurotransmitters. They are able to modulate neural signaling mediated by the main conventional neurotransmitters systems in the brain, including the monoaminergic, glutamatergic and GABAergic signaling systems. This review aims at discussing the fundamental aspects of NO- and endocannabinoid-mediated signaling in the brain, and how they can be related to the neurobiology of depression. Both preclinical and clinical evidence supporting the involvement of these atypical neurotransmitters in the neurobiology of depression, and in the antidepressant effects are presented here. The evidence is discussed on basis of their ability to modulate different neurotransmitter systems in the brain, including monoaminergic and glutamatergic ones. A better comprehension of NO and endocannabinoid signaling mechanisms in the neurobiology depression could provide new avenues for the development of novel non-monoamine based antidepressants.

  9. Modeling climate change impacts on maize growth with the focus on plant internal water transport

    NASA Astrophysics Data System (ADS)

    Heinlein, Florian; Biernath, Christian; Klein, Christian; Thieme, Christoph; Priesack, Eckart

    2015-04-01

    Based on climate change experiments in chambers and on field measurements, the scientific community expects regional and global changes of crop biomass production and yields. In central Europe one major aspect of climate change is the shift of precipitation towards winter months and the increase of extreme events, e.g. heat stress and heavy precipitation, during the main growing season in summer. To understand water uptake, water use, and transpiration rates by plants numerous crop models were developed. We tested the ability of two existing canopy models (CERES-Maize and SPASS) embedded in the model environment Expert-N5.0 to simulate the water balance, water use efficiency and crop growth. Additionally, sap flow was measured using heat-ratio measurement devices at the stem base of individual plants. The models were tested against data on soil water contents, as well as on evaporation and transpiration rates of Maize plants, which were grown on lysimeters at Helmholtz Zentrum München and in the field at the research station Scheyern, Germany, in summer 2013 and 2014. We present the simulation results and discuss observed shortcomings of the models. CERES-Maize and SPASS could simulate the measured dynamics of xylem sap flow. However, these models oversimplify plant water transport, and thus, cannot explain the underlying mechanisms. Therefore, to overcome these shortcomings, we additionally propose a new model, which is based on two coupled 1-D Richards equations, describing explicitly the plant and soil water transport. This model, which has previously successfully been applied to simulate water flux of 94 individual beech trees of an old-grown forest, will lead to a more mechanistic representation of the soil-plant-water-flow-continuum. This xylem water flux model was now implemented into the crop model SPASS and adjusted to simulate water flux of single maize plants. The modified version is presented and explained. Basic model input requirements are the plant

  10. Magnetotransport along a boundary: from coherent electron focusing to edge channel transport

    NASA Astrophysics Data System (ADS)

    Stegmann, T.; Wolf, D. E.; Lorke, A.

    2013-11-01

    We study theoretically how electrons, coherently injected at one point on the boundary of a two-dimensional electron system, are focused by a perpendicular magnetic field B onto another point on the boundary. Using the non-equilibrium Green's function approach, we calculate the generalized four-point Hall resistance Rxy as a function of B. In weak fields, Rxy shows the characteristic equidistant peaks observed in the experiment and explained by classical cyclotron motion along the boundary. In strong fields, Rxy shows a single extended plateau reflecting the quantum Hall effect. In intermediate fields, we find superimposed upon the lower Hall plateaus anomalous oscillations, which are neither periodic in 1/B (quantum Hall effect) nor in B (classical cyclotron motion). The oscillations are explained by the interference between the occupied edge channels, which causes beatings in Rxy. In the case of two occupied edge channels, these beatings constitute a new commensurability between the magnetic flux enclosed within the edge channels and the flux quantum. Introducing decoherence and a partially specular boundary shows that this new effect is quite robust.

  11. SIMULATION OF ENERGETIC PARTICLE TRANSPORT AND ACCELERATION AT SHOCK WAVES IN A FOCUSED TRANSPORT MODEL: IMPLICATIONS FOR MIXED SOLAR PARTICLE EVENTS

    SciTech Connect

    Kartavykh, Y. Y.; Dröge, W.; Gedalin, M.

    2016-03-20

    We use numerical solutions of the focused transport equation obtained by an implicit stochastic differential equation scheme to study the evolution of the pitch-angle dependent distribution function of protons in the vicinity of shock waves. For a planar stationary parallel shock, the effects of anisotropic distribution functions, pitch-angle dependent spatial diffusion, and first-order Fermi acceleration at the shock are examined, including the timescales on which the energy spectrum approaches the predictions of diffusive shock acceleration theory. We then consider the case that a flare-accelerated population of ions is released close to the Sun simultaneously with a traveling interplanetary shock for which we assume a simplified geometry. We investigate the consequences of adiabatic focusing in the diverging magnetic field on the particle transport at the shock, and of the competing effects of acceleration at the shock and adiabatic energy losses in the expanding solar wind. We analyze the resulting intensities, anisotropies, and energy spectra as a function of time and find that our simulations can naturally reproduce the morphologies of so-called mixed particle events in which sometimes the prompt and sometimes the shock component is more prominent, by assuming parameter values which are typically observed for scattering mean free paths of ions in the inner heliosphere and energy spectra of the flare particles which are injected simultaneously with the release of the shock.

  12. Temperature dependence of electrical properties of mixture of exogenous neurotransmitters dopamine and epinephrine

    NASA Astrophysics Data System (ADS)

    Patki, Mugdha; Patil, Vidya

    2016-05-01

    Neurotransmitters are chemical messengers that support the communication between the neurons. In vitro study of exogenous neurotransmitters Dopamine and Epinephrine and their mixture, carried out to learn about their electrical properties being dielectric constant and conductivity amongst others. Dielectric constant and conductivity of the selected neurotransmitters are found to increase with temperature. As a result, the time constant of the system increases with temperature. This change leads to increase in the time taken by the synapse to transport the action potential. The correlation between physical properties of exogenous neurotransmitters and psychological and physiological behaviour of human being may be understood with the help of current study. The response time of Epinephrine is in microseconds whereas response time of Dopamine is in milliseconds. The response time for both the neurotransmitters and their mixture is found to be increasing with temperature indicating the symptoms such as depression, apathy, chronic fatigue and low physical energy with no desire to exercise the body, which are observed during the fever.

  13. [Neurotransmitters, calcium signalling and neuronal communication].

    PubMed

    Eguiagaray, J G; Egea, J; Bravo-Cordero, J J; García, A G

    2004-04-01

    In this article we show some recent findings that constitute a great progress in the molecular knowledge of synaptic dynamics. To communicate, neurons use a code that includes electrical (action potentials) and chemical signals (neurotransmitters, neuromodulators). At the moment a great variety of molecules are known, whose neurotransmitter function in brain and the peripheral nervous system are out of question. Monoamines like acetylcholine, dopamine, noradrenaline, adrenaline, histamine, serotonin, glutamate, aspartate, glycine, ATP and GABA are good examples. Opioid neuropeptides, vasoactive intestinal peptide (VIP), neurokinines (substance P), somatostatin, neurotensin, neuropeptide Y, cholecystokinine, vasopressin or oxitocin have been related to the control of the stress response, sexual behaviour, food intake, pain, learning and memory, qualities that are also related to nitric oxide (NO). A great part of the molecular structure of the secretory machinery is known to be responsible for fast neurotransmitter release at the synapse, in response to action potentials. Proteins like sinaptobrevin (located in the membrane of the synaptic vesicle), sintaxin and SNAP-25 (both located at the presynaptic plasma membrane) constitute a trimeric complex which is responsible of the vesicular docking at the active sites for exocytosis. From this strategic location, vesicles release their neurotransmitter within few milliseconds, when the action potential invades the nerve terminal and activates the opening of the different subtypes of voltage-dependent Ca2+ channels. The asymmetric geographical distribution of each type of channel, in different neurons, rose the hypothesis that Ca2+ that enters through each subtype of channel is compartmentalised, thus favouring the generation of Ca2+ microdomains, in the cytosol and the nucleus, involved in different cellular functions. This great biochemical synaptic heterogeneity is facilitating the selection of many biological targets

  14. Microfluidic platform for neurotransmitter sensing based on cyclic voltammetry and dielectrophoresis for in vitro experiments.

    PubMed

    Mathault, Jessy; Zamprogno, Pauline; Greener, Jesse; Miled, Amine

    2015-08-01

    This paper presents a new microfluidic platform that can simultaneously measure and locally modulate neurotransmitter concentration in a neuron network. This work focuses on the development of a first prototype including a potentiostat and electrode functionalization to detect several neurotransmitter's simultaneously. We tested dopamine as proof of concept to validate functionality. The system is based on 320 bidirectional electrode array for dielectrophoretic manipulation and cyclic voltammetry. Each electrode is connected to a mechanical multiplexer in order to reduce noise interference and fully isolate the electrode. The multiplexing rate is 476 kHz and each electrode can drive a signal with an amplitude of 60 V pp for dielectrophoretic manipulation.

  15. Molecular mechanisms driving homeostatic plasticity of neurotransmitter release

    PubMed Central

    Lazarevic, Vesna; Pothula, Santosh; Andres-Alonso, Maria; Fejtova, Anna

    2013-01-01

    Homeostatic plasticity is a process by which neurons adapt to the overall network activity to keep their firing rates in a reasonable range. At the cellular level this kind of plasticity comprises modulation of cellular excitability and tuning of synaptic strength. In this review we concentrate on presynaptic homeostatic plasticity controlling the efficacy of neurotransmitter release from presynaptic boutons. While morphological and electrophysiological approaches were successful to describe homeostatic plasticity-induced changes in the presynaptic architecture and function, cellular and molecular mechanisms underlying those modifications remained largely unknown for a long time. We summarize the latest progress made in the understanding of homeostasis-induced regulation of different steps of the synaptic vesicle cycle and the molecular machineries involved in this process. We particularly focus on the role of presynaptic scaffolding proteins, which functionally and spatially organize synaptic vesicle clusters, neurotransmitter release sites and the associated endocytic machinery. These proteins turned out to be major presynaptic substrates for remodeling during homeostatic plasticity. Finally, we discuss cellular processes and signaling pathways acting during homeostatic molecular remodeling and their potential involvement in the maladaptive plasticity occurring in multiple neuropathologic conditions such as neurodegeneration, epilepsy and neuropsychiatric disorders. PMID:24348337

  16. Computational Studies of Glutamate Transporters

    PubMed Central

    Setiadi, Jeffry; Heinzelmann, Germano; Kuyucak, Serdar

    2015-01-01

    Glutamate is the major excitatory neurotransmitter in the human brain whose binding to receptors on neurons excites them while excess glutamate are removed from synapses via transporter proteins. Determination of the crystal structures of bacterial aspartate transporters has paved the way for computational investigation of their function and dynamics at the molecular level. Here, we review molecular dynamics and free energy calculation methods used in these computational studies and discuss the recent applications to glutamate transporters. The focus of the review is on the insights gained on the transport mechanism through computational methods, which otherwise is not directly accessible by experimental probes. Recent efforts to model the mammalian glutamate and other amino acid transporters, whose crystal structures have not been solved yet, are included in the review. PMID:26569328

  17. Modulation of neurotransmitter receptors and synaptic differentiation by proteins containing complement-related domains.

    PubMed

    Nakayama, Minoru; Hama, Chihiro

    2011-02-01

    Neurotransmitter receptors play central roles in basic neurotransmission and synaptic plasticity. Recent studies have revealed that some transmembrane and extracellular proteins bind to neurotransmitter receptors, forming protein complexes that are required for proper synaptic localization or gating of core receptor molecules. Consequently, the components of these complexes contribute to long-term potentiation, a process that is critical for learning and memory. Here, we review factors that regulate neurotransmitter receptors, with a focus on proteins containing CUB (complement C1r/C1s, Uegf, Bmp1) or CCP (complement control protein) domains, which are frequently found in complement system proteins. Proteins that contain these domains are structurally distinct from TARPs (transmembrane AMPA receptor regulatory proteins), and may constitute new protein families that modulate either the localization or function of neurotransmitter receptors. In addition, other CCP domain-containing proteins participate in dendritic patterning and/or synaptic differentiation, although current evidence has not identified any direct activities on neurotransmitter receptors. Some of these proteins are involved in pathologic conditions such as epileptic seizure and mental retardation. Together, these lines of information have shown that CUB and CCP domain-containing proteins contribute to a wide variety of neuronal events that ultimately establish neural circuits.

  18. Fabrication and electrical transport properties of binary Co-Si nanostructures prepared by focused electron beam-induced deposition

    SciTech Connect

    Porrati, F.; Huth, M.; Kaempken, B.; Terfort, A.

    2013-02-07

    CoSi-C binary alloys have been fabricated by focused electron beam-induced deposition by the simultaneous use of dicobaltoctacarbonyl, Co{sub 2}(CO){sub 8}, and neopentasilane, Si{sub 5}H{sub 12}, as precursor gases. By varying the relative flux of the precursors, alloys with variable chemical composition are obtained, as shown by energy dispersive x-ray analysis. Room temperature electrical resistivity measurements strongly indicate the formation of cobalt silicide and cobalt disilicide nanoclusters embedded in a carbonaceous matrix. Temperature-dependent electrical conductivity measurements show that the transport properties are governed by electron tunneling between neighboring CoSi or CoSi{sub 2} nanoclusters. In particular, by varying the metal content of the alloy, the electrical conductivity can be finely tuned from the insulating regime into the quasi-metallic tunneling coupling regime.

  19. Fabrication and electrical transport properties of binary Co-Si nanostructures prepared by focused electron beam-induced deposition

    NASA Astrophysics Data System (ADS)

    Porrati, F.; Kämpken, B.; Terfort, A.; Huth, M.

    2013-02-01

    CoSi-C binary alloys have been fabricated by focused electron beam-induced deposition by the simultaneous use of dicobaltoctacarbonyl, Co2(CO)8, and neopentasilane, Si5H12, as precursor gases. By varying the relative flux of the precursors, alloys with variable chemical composition are obtained, as shown by energy dispersive x-ray analysis. Room temperature electrical resistivity measurements strongly indicate the formation of cobalt silicide and cobalt disilicide nanoclusters embedded in a carbonaceous matrix. Temperature-dependent electrical conductivity measurements show that the transport properties are governed by electron tunneling between neighboring CoSi or CoSi2 nanoclusters. In particular, by varying the metal content of the alloy, the electrical conductivity can be finely tuned from the insulating regime into the quasi-metallic tunneling coupling regime.

  20. Neuronal release and successful astrocyte uptake of aminoacidergic neurotransmitters after spinal cord injury in lampreys.

    PubMed

    Fernández-López, Blanca; Valle-Maroto, Silvia María; Barreiro-Iglesias, Antón; Rodicio, María Celina

    2014-08-01

    In contrast to mammals, the spinal cord of lampreys spontaneously recovers from a complete spinal cord injury (SCI). Understanding the differences between lampreys and mammals in their response to SCI could provide valuable information to propose new therapies. Unique properties of the astrocytes of lampreys probably contribute to the success of spinal cord regeneration. The main aim of our study was to investigate, in the sea lamprey, the release of aminoacidergic neurotransmitters and the subsequent astrocyte uptake of these neurotransmitters during the first week following a complete SCI by detecting glutamate, GABA, glycine, Hu and cytokeratin immunoreactivities. This is the first time that aminoacidergic neurotransmitter release from neurons and the subsequent astrocytic response after SCI are analysed by immunocytochemistry in any vertebrate. Spinal injury caused the immediate loss of glutamate, GABA and glycine immunoreactivities in neurons close to the lesion site (except for the cerebrospinal fluid-contacting GABA cells). Only after SCI, astrocytes showed glutamate, GABA and glycine immunoreactivity. Treatment with an inhibitor of glutamate transporters (DL-TBOA) showed that neuronal glutamate was actively transported into astrocytes after SCI. Moreover, after SCI, a massive accumulation of inhibitory neurotransmitters around some reticulospinal axons was observed. Presence of GABA accumulation significantly correlated with a higher survival ability of these neurons. Our data show that, in contrast to mammals, astrocytes of lampreys have a high capacity to actively uptake glutamate after SCI. GABA may play a protective role that could explain the higher regenerative and survival ability of specific descending neurons of lampreys.

  1. The reverse operation of Na+/Cl−-coupled neurotransmitter transporters–why amphetamines take two to tango

    PubMed Central

    Sitte, Harald H.; Freissmuth, Michael

    2015-01-01

    Sodium-chloride coupled neurotransmitter transporters achieve reuptake of their physiological substrate by exploiting the pre-existing sodium-gradient across the cellular membrane. This terminates the action of previously released substrate in the synaptic cleft. However, a change of the transmembrane ionic gradients or specific binding of some psychostimulant drugs to these proteins, like amphetamine and its derivatives, induce reverse operation of neurotransmitter:sodium symporters. This effect eventually leads to an increase in the synaptic concentration of non-exocytotically released neurotransmitters [and – in the case of the norepinephrine transporters, underlies the well-known indirect sympathomimetic activity]. While this action has long been appreciated, the underlying mechanistic details have been surprisingly difficult to understand. Some aspects can be resolved by incorporating insights into the oligomeric nature of transporters, into the nature of the accompanying ion fluxes, and changes in protein kinase activities. PMID:19891736

  2. Characterizing Enzymatic Deposition for Microelectrode Neurotransmitter Detection

    SciTech Connect

    Hosein, W. K.; Yorita, A. M.; Tolosa, V. M.

    2016-08-12

    The enzyme immobilization process, one step in creating an enzymatic biosensor, was characterized and analyzed as a function of its physical properties. The neural glutamic biosensor is a flexible device, effectively minimizing trauma to the area of implantation. The Multielectrode Array (MEA) is composed primarily of a proprietary polymer which has been successfully implanted into human subjects in recent years. This polymer allows the device the pliability that other devices normally lack, though this poses some challenges to implantation. The electrodes are made of Platinum (Pt), and can range in number from eight to thirty two electrodes per device. These electrodes are electroplated with a semipermeable polymer layer to improve selectivity of the electrode to the neurotransmitter of interest, in this case glutamate. A signal is created from the interaction of glutamate in the brain with the glutamate oxidase (GluOx) which is immobilized on the surface of the electrode by using crosslinking chemistry in conjunction with glutaraldehyde and Bovine Serum Albumin (BSA). The glutamate is oxidized by glutamate oxidase, producing α-ketoglutarate and hydrogen peroxide (H2O2) as a by-product. The production of H2O2 is crucial for detection of the presence of the glutamate within the enzymatic coating, as it diffuses through the enzyme layer and oxidizes at the surface of the electrode. This oxidation is detectable by measurable change in the current using amperometry. Hence, the MEA allows for in vivo monitoring of neurotransmitter activity in real time. The sensitivity of the sensor to these neurotransmitters is dependent on the thickness of the layer, which is investigated in these experiments in order to optimize the efficacy of the device to detecting the substrate, once implanted.

  3. Pharmacology of neurotransmitter release: measuring exocytosis.

    PubMed

    Khvotchev, Mikhail; Kavalali, Ege T

    2008-01-01

    Neurotransmission in the nervous system is initiated at presynaptic terminals by fusion of synaptic vesicles with the plasma membrane and subsequent exocytic release of chemical transmitters. Currently, there are multiple methods to detect neurotransmitter release from nerve terminals, each with their own particular advantages and disadvantages. For instance, most commonly employed methods monitor actions of released chemical substances on postsynaptic receptors or artificial substrates such as carbon fibers. These methods are closest to the physiological setting because they have a rapid time resolution and they measure the action of the endogenous neurotransmitters rather than the signals emitted by exogenous probes. However, postsynaptic receptors only indirectly report neurotransmitter release in a form modified by the properties of receptors themselves, which are often nonlinear detectors of released substances. Alternatively, released chemical substances can be detected biochemically, albeit on a time scale slower than electrophysiological methods. In addition, in certain preparations, where presynaptic terminals are accessible to whole cell recording electrodes, fusion of vesicles with the plasma membrane can be monitored using capacitance measurements. In the last decade, in addition to electrophysiological and biochemical methods, several fluorescence imaging modalities have been introduced which report synaptic vesicle fusion, endocytosis, and recycling. These methods either take advantage of styryl dyes that can be loaded into recycling vesicles or exogenous expression of synaptic vesicle proteins tagged with a pH-sensitive GFP variant at regions facing the vesicle lumen. In this chapter, we will provide an overview of these methods with particular emphasis on their relative strengths and weaknesses and discuss the types of information one can obtain from them.

  4. PICKing on transporters.

    PubMed

    Deken, S L; Beckman, M L; Quick, M W

    2001-11-01

    Plasma membrane neurotransmitter transporters are regulators of extracellular transmitter levels in brain and are the primary sites of action for several drugs of abuse and therapy. Studies are beginning to reveal how neurons use synaptic machinery to modulate these regulators.

  5. Chloride binding site of neurotransmitter sodium symporters

    PubMed Central

    Kantcheva, Adriana K.; Quick, Matthias; Shi, Lei; Winther, Anne-Marie Lund; Stolzenberg, Sebastian; Weinstein, Harel; Javitch, Jonathan A.; Nissen, Poul

    2013-01-01

    Neurotransmitter:sodium symporters (NSSs) play a critical role in signaling by reuptake of neurotransmitters. Eukaryotic NSSs are chloride-dependent, whereas prokaryotic NSS homologs like LeuT are chloride-independent but contain an acidic residue (Glu290 in LeuT) at a site where eukaryotic NSSs have a serine. The LeuT-E290S mutant displays chloride-dependent activity. We show that, in LeuT-E290S cocrystallized with bromide or chloride, the anion is coordinated by side chain hydroxyls from Tyr47, Ser290, and Thr254 and the side chain amide of Gln250. The bound anion and the nearby sodium ion in the Na1 site organize a connection between their coordinating residues and the extracellular gate of LeuT through a continuous H-bond network. The specific insights from the structures, combined with results from substrate binding studies and molecular dynamics simulations, reveal an anion-dependent occlusion mechanism for NSS and shed light on the functional role of chloride binding. PMID:23641004

  6. The Role of Neurotrophins in Neurotransmitter Release

    PubMed Central

    Tyler, William J.; Perrett, Stephen P.; Pozzo-Miller, Lucas D.

    2009-01-01

    The neurotrophins (NTs) have recently been shown to elicit pronounced effects on quantal neurotransmitter release at both central and peripheral nervous system synapses. Due to their activity-dependent release, as well as the subcellular localization of both protein and receptor, NTs are ideally suited to modify the strength of neuronal connections by “fine-tuning” synaptic activity through direct actions at presynaptic terminals. Here, using BDNF as a prototypical example, the authors provide an update of recent evidence demonstrating that NTs enhance quantal neurotransmitter release at synapses through presynaptic mechanisms. The authors further propose that a potential target for NT actions at presynaptic terminals is the mechanism by which terminals retrieve synaptic vesicles after exocytosis. Depending on the temporal demands placed on synapses during high-frequency synaptic transmission, synapses may use two alternative modes of synaptic vesicle retrieval, the conventional slow endosomal recycling or a faster rapid retrieval at the active zone, referred to as “kiss-and-run.” By modulating Ca2+ microdomains associated with voltage-gated Ca2+ channels at active zones, NTs may elicit a switch from the slow to the fast mode of endocytosis of vesicles at presynaptic terminals during high-frequency synaptic transmission, allowing more reliable information transfer and neuronal signaling in the central nervous system. PMID:12467374

  7. Neurotransmitter signaling in the pathophysiology of microglia

    PubMed Central

    Domercq, María; Vázquez-Villoldo, Nuria; Matute, Carlos

    2013-01-01

    Microglial cells are the resident immune cells of the central nervous system. In the resting state, microglia are highly dynamic and control the environment by rapidly extending and retracting motile processes. Microglia are closely associated with astrocytes and neurons, particularly at the synapses, and more recent data indicate that neurotransmission plays a role in regulating the morphology and function of surveying/resting microglia, as they are endowed with receptors for most known neurotransmitters. In particular, microglia express receptors for ATP and glutamate, which regulate microglial motility. After local damage, the release of ATP induces microgliosis and activated microglial cells migrate to the site of injury, proliferate, and phagocytose cells, and cellular compartments. However, excessive activation of microglia could contribute to the progression of chronic neurodegenerative diseases, though the underlying mechanisms are still unclear. Microglia have the capacity to release a large number of substances that can be detrimental to the surrounding neurons, including glutamate, ATP, and reactive oxygen species. However, how altered neurotransmission following acute insults or chronic neurodegenerative conditions modulates microglial functions is still poorly understood. This review summarizes the relevant data regarding the role of neurotransmitter receptors in microglial physiology and pathology. PMID:23626522

  8. Chloride binding site of neurotransmitter sodium symporters.

    PubMed

    Kantcheva, Adriana K; Quick, Matthias; Shi, Lei; Winther, Anne-Marie Lund; Stolzenberg, Sebastian; Weinstein, Harel; Javitch, Jonathan A; Nissen, Poul

    2013-05-21

    Neurotransmitter:sodium symporters (NSSs) play a critical role in signaling by reuptake of neurotransmitters. Eukaryotic NSSs are chloride-dependent, whereas prokaryotic NSS homologs like LeuT are chloride-independent but contain an acidic residue (Glu290 in LeuT) at a site where eukaryotic NSSs have a serine. The LeuT-E290S mutant displays chloride-dependent activity. We show that, in LeuT-E290S cocrystallized with bromide or chloride, the anion is coordinated by side chain hydroxyls from Tyr47, Ser290, and Thr254 and the side chain amide of Gln250. The bound anion and the nearby sodium ion in the Na1 site organize a connection between their coordinating residues and the extracellular gate of LeuT through a continuous H-bond network. The specific insights from the structures, combined with results from substrate binding studies and molecular dynamics simulations, reveal an anion-dependent occlusion mechanism for NSS and shed light on the functional role of chloride binding.

  9. Imaging neurotransmitter release kinetics in living cells

    SciTech Connect

    Tan, Weihong; Yeung, E.S.; Haydon, P.G.

    1996-12-31

    A new UV-laser based optical microscope and CCD detection system has been developed to image neurotransmitter in living biological cells. We demonstrate the detection of serotonin that has been taken up into and released from individual living glial cells (astrocytes) based on its native fluorescence. The detection methodology has high sensitivity, low limit of detection and does not require coupling to fluorescence dyes. We have studied serotonin uptake kinetics and its release dynamics in single glial cells. Different regions of a glial cell have taken up different amounts of serotonin with a variety of kinetics. Similarly, different serotonin release mechanisms have been observed in different astrocyte cell regions. The temporal resolution of this detection system is as fast as 50 ms, and the spatial resolution is diffraction limited. We will also report on single enzyme molecule reaction studies and single metal ion detection based on CCD imaging of pL reaction vials formed by micromachining on fused silica.

  10. 13C MRS studies of neuroenergetics and neurotransmitter cycling in humans.

    PubMed

    Rothman, Douglas L; De Feyter, Henk M; de Graaf, Robin A; Mason, Graeme F; Behar, Kevin L

    2011-10-01

    In the last 25 years, (13)C MRS has been established as the only noninvasive method for the measurement of glutamate neurotransmission and cell-specific neuroenergetics. Although technically and experimentally challenging, (13)C MRS has already provided important new information on the relationship between neuroenergetics and neuronal function, the energy cost of brain function, the high neuronal activity in the resting brain state and how neuroenergetics and neurotransmitter cycling are altered in neurological and psychiatric disease. In this article, the current state of (13)C MRS as it is applied to the study of neuroenergetics and neurotransmitter cycling in humans is reviewed. The focus is predominantly on recent findings in humans regarding metabolic pathways, applications to clinical research and the technical status of the method. Results from in vivo (13)C MRS studies in animals are discussed from the standpoint of the validation of MRS measurements of neuroenergetics and neurotransmitter cycling, and where they have helped to identify key questions to address in human research. Controversies concerning the relationship between neuroenergetics and neurotransmitter cycling and factors having an impact on the accurate determination of fluxes through mathematical modeling are addressed. We further touch upon different (13)C-labeled substrates used to study brain metabolism, before reviewing a number of human brain diseases investigated using (13)C MRS. Future technological developments are discussed that will help to overcome the limitations of (13)C MRS, with special attention given to recent developments in hyperpolarized (13)C MRS.

  11. A 109 neutrons/pulse transportable pulsed D-D neutron source based on flexible head plasma focus unit

    NASA Astrophysics Data System (ADS)

    Niranjan, Ram; Rout, R. K.; Srivastava, R.; Kaushik, T. C.; Gupta, Satish C.

    2016-03-01

    A 17 kJ transportable plasma focus (PF) device with flexible transmission lines is developed and is characterized. Six custom made capacitors are used for the capacitor bank (CB). The common high voltage plate of the CB is fixed to a centrally triggered spark gap switch. The output of the switch is coupled to the PF head through forty-eight 5 m long RG213 cables. The CB has a quarter time-period of 4 μs and an estimated current of 506 kA is delivered to the PF device at 17 kJ (60 μF, 24 kV) energy. The average neutron yield measured using silver activation detector in the radial direction is (7.1 ± 1.4) × 108 neutrons/shot over 4π sr at 5 mbar optimum D2 pressure. The average neutron yield is more in the axial direction with an anisotropy factor of 1.33 ± 0.18. The average neutron energies estimated in the axial as well as in the radial directions are (2.90 ± 0.20) MeV and (2.58 ± 0.20) MeV, respectively. The flexibility of the PF head makes it useful for many applications where the source orientation and the location are important factors. The influence of electromagnetic interferences from the CB as well as from the spark gap on applications area can be avoided by putting a suitable barrier between the bank and the PF head.

  12. Secondary Abnormalities of Neurotransmitters in Infants with Neurological Disorders

    ERIC Educational Resources Information Center

    Garcia-Cazorla, A.; Serrano, M.; Perez-Duenas, B.; Gonzalez, V.; Ormazabal, A.; Pineda, M.; Fernandez-Alvarez, E.; Campistol, J. M. D.; Artuch, R. M. D.

    2007-01-01

    Neurotransmitters are essential in young children for differentiation and neuronal growth of the developing nervous system. We aimed to identify possible factors related to secondary neurotransmitter abnormalities in pediatric patients with neurological disorders. We analyzed cerebrospinal fluid (CSF) and biogenic amine metabolites in 56 infants…

  13. Chronic paroxetine treatment: effects on other non-serotonergic neurotransmitter systems.

    PubMed

    Ballesteros-Zebadua, Paola; Manjarrez-Marmolejo, Joaquin; Franco-Perez, Javier

    2013-12-01

    Due to its efficacy and acceptability, paroxetine is situated in the top ten of drugs prescribed for the treatment of major depression and essentially all anxiety disorders. Adults under paroxetine treatment report relief after 4-6 weeks of administration; furthermore, this drug can be prescribed for periods lasting longer than one year. Therefore, paroxetine treatment has a pattern of ingestion that is mainly chronic rather than acute. There is a considerable number of reviews in the literature concerning the effects of paroxetine on the serotonergic system; however, the alterations caused by chronic ingestion of this drug in other neurotransmitter systems have received little attention. For this reason, we consider very important to review the experimental studies concerning the effects of chronic paroxetine intake on neurotransmitter levels, neuronal firing rate and the expression of receptors and transporters in different neurotransmitter systems in the brain. According to the experimental data analyzed in this work, we can establish that long-term paroxetine intake has the ability to increase GABA, glutamate, dopamine and noradrenaline levels in the brain. Furthermore, high levels of AMPA, orexine-1,2 and histamine-1 receptors have been reported in different brain regions after treatment with paroxetine over several weeks. In addition, paroxetine has differential effects on neuropeptide systems, such as galanine, opioid receptors and substance P. Available data lead us to establish that chronic ingestion of paroxetine induces changes in several neurotransmitters and neuropeptides, thus illuminating how each one may contribute to the antidepressant and anxiolytic response elicited by this drug. We consider that all reported changes in the neurotransmitter systems should be further considered to individualize clinical treatment and, in the case of patients taking a drug "cocktail", to gain better control over drug interactions and adverse effects.

  14. Glycine Transporters and Their Inhibitors

    NASA Astrophysics Data System (ADS)

    Gilfillan, Robert; Kerr, Jennifer; Walker, Glenn; Wishart, Grant

    Glycine plays a ubiquitous role in many biological processes. In the central nervous system it serves as an important neurotransmitter acting as an agonist at strychnine-sensitive glycine receptors and as an essential co-agonist with glutamate at the NMDA receptor complex. Control of glycine concentrations in the vicinity of these receptors is mediated by the specific glycine transporters, GlyT1 and GlyT2. Inhibition of these transporters has been postulated to be of potential benefit in several therapeutic indications including schizophrenia and pain. In this review we discuss our current knowledge of glycine transporters and focus on recent advances in the medicinal chemistry of GlyT1 and GlyT2 inhibitors.

  15. Dirty electricity, chronic stress, neurotransmitters and disease.

    PubMed

    Milham, Samuel; Stetzer, David

    2013-12-01

    Dirty electricity, also called electrical pollution, is high-frequency voltage transients riding along the 50 or 60 Hz electricity provided by the electric utilities. It is generated by arcing, by sparking and by any device that interrupts current flow, especially switching power supplies. It has been associated with cancer, diabetes and attention deficit hyperactivity disorder in humans. Epidemiological evidence also links dirty electricity to most of the diseases of civilization including cancer, cardiovascular disease, diabetes and suicide, beginning at the turn of the twentieth century. The dirty electricity level in a public library was reduced from over 10 000 Graham/Stetzer (G/S) units to below 50 G/S units by installing plug-in capacitive filters. Before cleanup, the urinary dopamine level of only one of seven volunteers was within normal levels, while four of seven phenylethylamine levels were normal. After an initial decline, over the next 18 weeks the dopamine levels gradually increased to an average of over 215 μg/g creatinine, which is well above 170 μg/g creatinine, the high normal level for the lab. Average phenylethylamine levels also rose gradually to slightly above 70 μg/g creatinine, the high normal level for the lab. Neurotransmitters may be biomarkers for dirty electricity and other electromagnetic field exposures. We believe that dirty electricity is a chronic stressor of electrified populations and is responsible for many of their disease patterns.

  16. Effect of Dimerization on the Dynamics of Neurotransmitter:Sodium Symporters.

    PubMed

    Gur, Mert; Cheng, Mary Hongying; Zomot, Elia; Bahar, Ivet

    2017-02-07

    Dimerization is a common feature among the members of the neurotransmitter:sodium symporter (NSS) family of membrane proteins. Yet, the effect of dimerization on the mechanism of action of NSS members is not fully understood. In this study, we examined the collective dynamics of two members of the family, leucine transporter (LeuT) and dopamine transporter (DAT), to assess the significance of dimerization in modulating the functional motions of the monomers. We used to this aim the anisotropic network model (ANM), an efficient and robust method for modeling the intrinsic motions of proteins and their complexes. Transporters belonging to the NSS family are known to alternate between outward-facing (OF) and inward-facing (IF) states, which enables the uptake and release of their substrate (neurotransmitter) respectively, as the substrate is transported from the exterior to the interior of the cell. In both LeuT and DAT, dimerization is found to alter the collective motions intrinsically accessible to the individual monomers in favor of the functional transitions (OF ↔ IF), suggesting that dimerization may play a role in facilitating transport.

  17. Neurotransmitter receptors as targets for pesticides.

    PubMed

    Eldefrawi, M E; Eldefrawi, A T

    1983-01-01

    Nicotinic and muscarinic acetylcholine (ACh) receptors have been identified biochemically by means of their specific binding of [3H] alpha-bungarotoxin ([3H]alpha-BGT) and [3H]quinuclidinyl benzilate, respectively. There are some differences in the drug specificities, and sensitivities to active group reagents, of these receptors in insects when compared to those in vertebrates. Also, insect brain contains more nicotinic than muscarinic receptors, while the reverse is found in mammalian brain. Insect brain contains a third kind of putative ACh-receptor that is relatively soluble and is both nicotinic and muscarinic in its pharmacology but does not bind alpha-BGT. Toxic nicotine and analogs bind to it with high affinities. Several organophosphorus and carbamate insecticides and nereistoxin bind with high affinities to the nicotinic ACh-receptor of the electric organ of Torpedo. A few chlorinated hydrocarbon insecticides and derivatives interact with Torpedo nicotinic ACh-receptors, not at their 'receptor' sites but at their allosteric or 'channel' sites (which are identified by their specific binding of [3H]perhydrohistrionicotoxin). A few also bind to mammalian brain muscarinic receptors. The most potent on both receptors is the acaricide chlorobenzilate. Pyrethrins and synthetic pyrethroids also bind with high affinities to the channel sites of the Torpedo nicotinic ACh-receptor, though not to its receptor sites. Another group that binds to ACh-receptors is the organic and inorganic mercury compounds, which interact with both the Torpedo nicotinic and rat brain muscarinic receptors. Thus, neurotransmitter receptors act as molecular targets, primary or secondary for different pesticides.

  18. Glucagon-related peptide 1 (GLP-1): hormone and neurotransmitter.

    PubMed

    Larsen, Philip J; Holst, Jens Juul

    2005-06-15

    The interest in glucagon-like petide-1 (GLP-1) and other pre-proglucagon derived peptides has risen almost exponentially since seminal papers in the early 1990s proposed to use GLP-1 agonists as therapeutic agents for treatment of type 2 diabetes. A wealth of interesting studies covering both normal and pathophysiological role of GLP-1 have been published over the last two decades and our understanding of GLP-1 action has widened considerably. In the present review, we have tried to cover our current understanding of GLP-1 actions both as a peripheral hormone and as a central neurotransmitter. From an initial focus on glycaemic control, GLP-1 research has been diverted to study its role in energy homeostasis, neurodegeneration, cognitive functions, anxiety and many more functions. With the upcoming introduction of GLP-1 agonists on the pharmaceutical venue, we have witnessed an outstanding example of how initial ideas from basic science laboratories have paved their way to become a novel therapeutic strategy to fight diabetes.

  19. Biophysical Approaches to the Study of LeuT, a Prokaryotic Homolog of Neurotransmitter Sodium Symporters.

    PubMed

    Singh, Satinder K; Pal, Aritra

    2015-01-01

    Ion-coupled secondary transport is utilized by multiple integral membrane proteins as a means of achieving the thermodynamically unfavorable translocation of solute molecules across the lipid bilayer. The chemical nature of these molecules is diverse and includes sugars, amino acids, neurotransmitters, and other ions. LeuT is a sodium-coupled, nonpolar amino acid symporter and eubacterial member of the solute carrier 6 (SLC6) family of Na(+)/Cl(-)-dependent neurotransmitter transporters. Eukaryotic counterparts encompass the clinically and pharmacologically significant transporters for γ-aminobutyric acid (GABA), glycine, serotonin (5-hydroxytryptamine, 5-HT), dopamine (DA), and norepinephrine (NE). Since the crystal structure of LeuT was first solved in 2005, subsequent crystallographic, binding, flux, and spectroscopic studies, complemented with homology modeling and molecular dynamic simulations, have allowed this protein to emerge as a remarkable mechanistic paradigm for both the SLC6 class as well as several other sequence-unrelated SLCs whose members possess astonishingly similar architectures. Despite yielding groundbreaking conceptual advances, this vast treasure trove of data has also been the source of contentious hypotheses. This chapter will present a historical scientific overview of SLC6s; recount how the initial and subsequent LeuT structures were solved, describing the insights they each provided; detail the accompanying functional techniques, emphasizing how they either supported or refuted the static crystallographic data; and assemble these individual findings into a mechanism of transport and inhibition.

  20. Biophysical Approaches to the Study of LeuT, a Prokaryotic Homolog of Neurotransmitter Sodium Symporters

    PubMed Central

    Singh, Satinder K.; Pal, Aritra

    2016-01-01

    Ion-coupled secondary transport is utilized by multiple integral membrane proteins as a means of achieving the thermodynamically unfavorable translocation of solute molecules across the lipid bilayer. The chemical nature of these molecules is diverse and includes sugars, amino acids, neurotransmitters, and other ions. LeuT is a sodium-coupled, nonpolar amino acid symporter and eubacterial member of the solute carrier 6 (SLC6) family of Na+/Cl−-dependent neurotransmitter transporters. Eukaryotic counterparts encompass the clinically and pharmacologically significant transporters for γ-aminobutyric acid (GABA), glycine, serotonin (5-hydroxytryptamine, 5-HT), dopamine (DA), and norepinephrine (NE). Since the crystal structure of LeuT was first solved in 2005, subsequent crystallographic, binding, flux, and spectroscopic studies, complemented with homology modeling and molecular dynamic simulations, have allowed this protein to emerge as a remarkable mechanistic paradigm for both the SLC6 class as well as several other sequence-unrelated SLCs whose members possess astonishingly similar architectures. Despite yielding groundbreaking conceptual advances, this vast treasure trove of data has also been the source of contentious hypotheses. This chapter will present a historical scientific overview of SLC6s; recount how the initial and subsequent LeuT structures were solved, describing the insights they each provided; detail the accompanying functional techniques, emphasizing how they either supported or refuted the static crystallographic data; and assemble these individual findings into a mechanism of transport and inhibition. PMID:25950965

  1. Transition metal ion FRET uncovers K+ regulation of a neurotransmitter/sodium symporter

    PubMed Central

    Billesbølle, Christian B.; Mortensen, Jonas S.; Sohail, Azmat; Schmidt, Solveig G.; Shi, Lei; Sitte, Harald H.; Gether, Ulrik; Loland, Claus J.

    2016-01-01

    Neurotransmitter/sodium symporters (NSSs) are responsible for Na+-dependent reuptake of neurotransmitters and represent key targets for antidepressants and psychostimulants. LeuT, a prokaryotic NSS protein, constitutes a primary structural model for these transporters. Here we show that K+ inhibits Na+-dependent binding of substrate to LeuT, promotes an outward-closed/inward-facing conformation of the transporter and increases uptake. To assess K+-induced conformational dynamics we measured fluorescence resonance energy transfer (FRET) between fluorescein site-specifically attached to inserted cysteines and Ni2+ bound to engineered di-histidine motifs (transition metal ion FRET). The measurements supported K+-induced closure of the transporter to the outside, which was counteracted by Na+ and substrate. Promoting an outward-open conformation of LeuT by mutation abolished the K+-effect. The K+-effect depended on an intact Na1 site and mutating the Na2 site potentiated K+ binding by facilitating transition to the inward-facing state. The data reveal an unrecognized ability of K+ to regulate the LeuT transport cycle. PMID:27678200

  2. Transition metal ion FRET uncovers K(+) regulation of a neurotransmitter/sodium symporter.

    PubMed

    Billesbølle, Christian B; Mortensen, Jonas S; Sohail, Azmat; Schmidt, Solveig G; Shi, Lei; Sitte, Harald H; Gether, Ulrik; Loland, Claus J

    2016-09-28

    Neurotransmitter/sodium symporters (NSSs) are responsible for Na(+)-dependent reuptake of neurotransmitters and represent key targets for antidepressants and psychostimulants. LeuT, a prokaryotic NSS protein, constitutes a primary structural model for these transporters. Here we show that K(+) inhibits Na(+)-dependent binding of substrate to LeuT, promotes an outward-closed/inward-facing conformation of the transporter and increases uptake. To assess K(+)-induced conformational dynamics we measured fluorescence resonance energy transfer (FRET) between fluorescein site-specifically attached to inserted cysteines and Ni(2+) bound to engineered di-histidine motifs (transition metal ion FRET). The measurements supported K(+)-induced closure of the transporter to the outside, which was counteracted by Na(+) and substrate. Promoting an outward-open conformation of LeuT by mutation abolished the K(+)-effect. The K(+)-effect depended on an intact Na1 site and mutating the Na2 site potentiated K(+) binding by facilitating transition to the inward-facing state. The data reveal an unrecognized ability of K(+) to regulate the LeuT transport cycle.

  3. Overview of transport and MHD stability study: focusing on the impact of magnetic field topology in the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Ida, K.; Nagaoka, K.; Inagaki, S.; Kasahara, H.; Evans, T.; Yoshinuma, M.; Kamiya, K.; Ohdach, S.; Osakabe, M.; Kobayashi, M.; Sudo, S.; Itoh, K.; Akiyama, T.; Emoto, M.; Dinklage, A.; Du, X.; Fujii, K.; Goto, M.; Goto, T.; Hasuo, M.; Hidalgo, C.; Ichiguchi, K.; Ishizawa, A.; Jakubowski, M.; Kawamura, G.; Kato, D.; Morita, S.; Mukai, K.; Murakami, I.; Murakami, S.; Narushima, Y.; Nunami, M.; Ohno, N.; Pablant, N.; Sakakibara, S.; Seki, T.; Shimozuma, T.; Shoji, M.; Tanaka, K.; Tokuzawa, T.; Todo, Y.; Wang, H.; Yokoyama, M.; Yamada, H.; Takeiri, Y.; Mutoh, T.; Imagawa, S.; Mito, T.; Nagayama, Y.; Watanabe, K. Y.; Ashikawa, N.; Chikaraishi, H.; Ejiri, A.; Furukawa, M.; Fujita, T.; Hamaguchi, S.; Igami, H.; Isobe, M.; Masuzaki, S.; Morisaki, T.; Motojima, G.; Nagasaki, K.; Nakano, H.; Oya, Y.; Suzuki, C.; Suzuki, Y.; Sakamoto, R.; Sakamoto, M.; Sanpei, A.; Takahashi, H.; Tsuchiya, H.; Tokitani, M.; Ueda, Y.; Yoshimura, Y.; Yamamoto, S.; Nishimura, K.; Sugama, H.; Yamamoto, T.; Idei, H.; Isayama, A.; Kitajima, S.; Masamune, S.; Shinohara, K.; Bawankar, P. S.; Bernard, E.; von Berkel, M.; Funaba, H.; Huang, X. L.; T., Ii; Ido, T.; Ikeda, K.; Kamio, S.; Kumazawa, R.; Kobayashi, T.; Moon, C.; Muto, S.; Miyazawa, J.; Ming, T.; Nakamura, Y.; Nishimura, S.; Ogawa, K.; Ozaki, T.; Oishi, T.; Ohno, M.; Pandya, S.; Shimizu, A.; Seki, R.; Sano, R.; Saito, K.; Sakaue, H.; Takemura, Y.; Tsumori, K.; Tamura, N.; Tanaka, H.; Toi, K.; Wieland, B.; Yamada, I.; Yasuhara, R.; Zhang, H.; Kaneko, O.; Komori, A.; Collaborators

    2015-10-01

    The progress in the understanding of the physics and the concurrent parameter extension in the large helical device since the last IAEA-FEC, in 2012 (Kaneko O et al 2013 Nucl. Fusion 53 095024), is reviewed. Plasma with high ion and electron temperatures (Ti(0) ˜ Te(0) ˜ 6 keV) with simultaneous ion and electron internal transport barriers is obtained by controlling recycling and heating deposition. A sign flip of the nondiffusive term of impurity/momentum transport (residual stress and convection flow) is observed, which is associated with the formation of a transport barrier. The impact of the topology of three-dimensional magnetic fields (stochastic magnetic fields and magnetic islands) on heat momentum, particle/impurity transport and magnetohydrodynamic stability is also discussed. In the steady state operation, a 48 min discharge with a line-averaged electron density of 1 × 1019 m-3 and with high electron and ion temperatures (Ti(0) ˜ Te(0) ˜ 2 keV), resulting in 3.36 GJ of input energy, is achieved.

  4. Glycine receptors support excitatory neurotransmitter release in developing mouse visual cortex

    PubMed Central

    Kunz, Portia A; Burette, Alain C; Weinberg, Richard J; Philpot, Benjamin D

    2012-01-01

    Glycine receptors (GlyRs) are found in most areas of the brain, and their dysfunction can cause severe neurological disorders. While traditionally thought of as inhibitory receptors, presynaptic-acting GlyRs (preGlyRs) can also facilitate glutamate release under certain circumstances, although the underlying molecular mechanisms are unknown. In the current study, we sought to better understand the role of GlyRs in the facilitation of excitatory neurotransmitter release in mouse visual cortex. Using whole-cell recordings, we found that preGlyRs facilitate glutamate release in developing, but not adult, visual cortex. The glycinergic enhancement of neurotransmitter release in early development depends on the high intracellular to extracellular Cl− gradient maintained by the Na+–K+–2Cl− cotransporter and requires Ca2+ entry through voltage-gated Ca2+ channels. The glycine transporter 1, localized to glial cells, regulates extracellular glycine concentration and the activation of these preGlyRs. Our findings demonstrate a developmentally regulated mechanism for controlling excitatory neurotransmitter release in the neocortex. PMID:22988142

  5. Biochemical and Neurotransmitters Changes Associated with Tramadol in Streptozotocin-Induced Diabetes in Rats

    PubMed Central

    Ezzeldin, Essam; Souror, Wafaa A. H.; El-Nahhas, Toqa; Soudi, Abdel Nasser M. M.; Shahat, Abdelaaty A.

    2014-01-01

    The incidence of diabetes is increasing worldwide. Chronic neuropathic pain occurs in approximately 25% of diabetic patients. Tramadol, an atypical analgesic with a unique dual mechanism of action, is used in the management of painful diabetic neuropathy. It acts on monoamine transporters to inhibit the reuptake of norepinephrine (NE), serotonin (5-HT), and dopamine (DA). The purpose of this study was to evaluate the effects of diabetes on the brain neurotransmitter alterations induced by tramadol in rats, and to study the hepatic and renal toxicities of the drug. Eighty Sprague-Dawley rats were divided randomly into two sets: the normal set and the diabetic set. Diabetes was induced in rats. Tramadol was administered orally once daily for 28 days. The levels of DA, NE, and 5-HT in cerebral cortex, thalamus/hypothalamus, midbrain, and brainstem were evaluated in rats. In addition, the renal toxicity and histopathological effects of the drug were assessed. The induction of diabetes altered neurotransmitter levels. Oral administration of tramadol significantly decreased the neurotransmitter levels. Diabetes significantly altered the effects of tramadol in all brain regions. Tramadol affected function and histology of the liver and kidney. The clinical effects of tramadol in diabetic patients should be stressed. PMID:24971322

  6. Selected hormonal and neurotransmitter mechanisms regulating feed intake in sheep.

    PubMed

    Sartin, J L; Daniel, J A; Whitlock, B K; Wilborn, R R

    2010-11-01

    Appetite control is a major issue in normal growth and in suboptimal growth performance settings. A number of hormones, in particular leptin, activate or inhibit orexigenic or anorexigenic neurotransmitters within the arcuate nucleus of the hypothalamus, where feed intake regulation is integrated. Examples of appetite regulatory neurotransmitters are the stimulatory neurotransmitters neuropeptide Y (NPY), agouti-related protein (AgRP), orexin and melanin-concentrating hormone and the inhibitory neurotransmitter, melanocyte-stimulating hormone (MSH). Examination of messenger RNA (using in situ hybridization and real-time PCR) and proteins (using immunohistochemistry) for these neurotransmitters in ruminants has indicated that physiological regulation occurs in response to fasting for several of these critical genes and proteins, especially AgRP and NPY. Moreover, intracerebroventricular injection of each of the four stimulatory neurotransmitters can increase feed intake in sheep and may also regulate either growth hormone, luteinizing hormone, cortisol or other hormones. In contrast, both leptin and MSH are inhibitory to feed intake in ruminants. Interestingly, the natural melanocortin-4 receptor (MC4R) antagonist, AgRP, as well as NPY can prevent the inhibition of feed intake after injection of endotoxin (to model disease suppression of appetite). Thus, knowledge of the mechanisms regulating feed intake in the hypothalamus may lead to mechanisms to increase feed intake in normal growing animals and prevent the wasting effects of severe disease in animals.

  7. Radiotracers for PET and SPECT studies of neurotransmitter systems

    SciTech Connect

    Fowler, J.S.

    1991-01-01

    The study of neurotransmitter systems is one of the major thrusts in emission tomography today. The current generation of Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) radiotracers examines neurotransmitter properties from a number of different perspectives including their pre and post synaptic sites and the activity of the enzymes which regulate their concentration. Although the dopamine system has been the most extensively investigated, other neurotransmitter systems including the acetylcholine muscarine, serotonin, benzodiazepine, opiate, NMDA and others are also under intensive development. Enzymes involved in the synthesis and regulation of neurotransmitter concentration, for example monoamine oxidase and amino acid decarboxylase has also been probed in vivo. Medical applications range from the study of normal function and the characterization of neurotransmitter activity in neurological and psychiatric diseases and in heart disease and cancer to the study of the binding of therapeutic drugs and substances of abuse. This chapter will provide an overview of the current generation of radiotracers for PET and SPECT studies of neurotransmitter systems including radiotracer design, synthesis localization mechanisms and applications in emission tomography. 60 refs., 1 tab.

  8. TRANSPORT

    EPA Science Inventory

    Presentation outline: transport principles, effective solubility; gasoline composition; and field examples (plume diving).
    Presentation conclusions: MTBE transport follows from - phyiscal and chemical properties and hydrology. Field examples show: MTBE plumes > benzene plu...

  9. IL-4 Inhibits IL-1β-Induced Depressive-Like Behavior and Central Neurotransmitter Alterations.

    PubMed

    Park, Hyun-Jung; Shim, Hyun-Soo; An, Kyungeh; Starkweather, Angela; Kim, Kyung Soo; Shim, Insop

    2015-01-01

    It has been known that activation of the central innate immune system or exposure to stress can disrupt balance of anti-/proinflammatory cytokines. The aim of the present study was to investigate the role of pro- and anti-inflammatory cytokines in the modulation of depressive-like behaviors, the hormonal and neurotransmitter systems in rats. We investigated whether centrally administered IL-1β is associated with activation of CNS inflammatory pathways and behavioral changes and whether treatment with IL-4 could modulate IL-1β-induced depressive-like behaviors and central neurotransmitter systems. Infusion of IL-4 significantly decreased IL-1β-induced anhedonic responses and increased social exploration and total activity. Treatment with IL-4 markedly blocked IL-1β-induced increase in PGE2 and CORT levels. Also, IL-4 reduced IL-1β-induced 5-HT levels by inhibiting tryptophan hydroxylase (TPH) mRNA and activating serotonin transporter (SERT) in the hippocampus, and levels of NE were increased by activating tyrosine hydroxylase (TH) mRNA expression. These results demonstrate that IL-4 may locally contribute to the regulation of noradrenergic and serotonergic neurotransmission and may inhibit IL-1β-induced behavioral and immunological changes. The present results suggest that IL-4 modulates IL-1β-induced depressive behavior by inhibiting IL-1β-induced central glial activation and neurotransmitter alterations. IL-4 reduced central and systemic mediatory inflammatory activation, as well as reversing the IL-1β-induced alterations in neurotransmitter levels. The present findings contribute a biochemical pathway regulated by IL-4 that may have therapeutic utility for treatment of IL-1β-induced depressive behavior and neuroinflammation which warrants further study.

  10. IL-4 Inhibits IL-1β-Induced Depressive-Like Behavior and Central Neurotransmitter Alterations

    PubMed Central

    Park, Hyun-Jung; Shim, Hyun-Soo; An, Kyungeh; Starkweather, Angela; Kim, Kyung Soo; Shim, Insop

    2015-01-01

    It has been known that activation of the central innate immune system or exposure to stress can disrupt balance of anti-/proinflammatory cytokines. The aim of the present study was to investigate the role of pro- and anti-inflammatory cytokines in the modulation of depressive-like behaviors, the hormonal and neurotransmitter systems in rats. We investigated whether centrally administered IL-1β is associated with activation of CNS inflammatory pathways and behavioral changes and whether treatment with IL-4 could modulate IL-1β-induced depressive-like behaviors and central neurotransmitter systems. Infusion of IL-4 significantly decreased IL-1β-induced anhedonic responses and increased social exploration and total activity. Treatment with IL-4 markedly blocked IL-1β-induced increase in PGE2 and CORT levels. Also, IL-4 reduced IL-1β-induced 5-HT levels by inhibiting tryptophan hydroxylase (TPH) mRNA and activating serotonin transporter (SERT) in the hippocampus, and levels of NE were increased by activating tyrosine hydroxylase (TH) mRNA expression. These results demonstrate that IL-4 may locally contribute to the regulation of noradrenergic and serotonergic neurotransmission and may inhibit IL-1β-induced behavioral and immunological changes. The present results suggest that IL-4 modulates IL-1β-induced depressive behavior by inhibiting IL-1β-induced central glial activation and neurotransmitter alterations. IL-4 reduced central and systemic mediatory inflammatory activation, as well as reversing the IL-1β-induced alterations in neurotransmitter levels. The present findings contribute a biochemical pathway regulated by IL-4 that may have therapeutic utility for treatment of IL-1β-induced depressive behavior and neuroinflammation which warrants further study. PMID:26417153

  11. Neurotransmitter/sodium symporter orthologue LeuT has a single high-affinity substrate site.

    PubMed

    Piscitelli, Chayne L; Krishnamurthy, Harini; Gouaux, Eric

    2010-12-23

    Neurotransmitter/sodium symporters (NSSs) couple the uptake of neurotransmitter with one or more sodium ions, removing neurotransmitter from the synaptic cleft. NSSs are essential to the function of chemical synapses, are associated with multiple neurological diseases and disorders, and are the targets of therapeutic and illicit drugs. LeuT, a prokaryotic orthologue of the NSS family, is a model transporter for understanding the relationships between molecular mechanism and atomic structure in a broad range of sodium-dependent and sodium-independent secondary transporters. At present there is a controversy over whether there are one or two high-affinity substrate binding sites in LeuT. The first-reported crystal structure of LeuT, together with subsequent functional and structural studies, provided direct evidence for a single, high-affinity, centrally located substrate-binding site, defined as the S1 site. Recent binding, flux and molecular simulation studies, however, have been interpreted in terms of a model where there are two high-affinity binding sites: the central, S1, site and a second, the S2 site, located within the extracellular vestibule. Furthermore, it was proposed that the S1 and S2 sites are allosterically coupled such that occupancy of the S2 site is required for the cytoplasmic release of substrate from the S1 site. Here we address this controversy by performing direct measurement of substrate binding to wild-type LeuT and to S2 site mutants using isothermal titration calorimetry, equilibrium dialysis and scintillation proximity assays. In addition, we perform uptake experiments to determine whether the proposed allosteric coupling between the putative S2 site and the S1 site manifests itself in the kinetics of substrate flux. We conclude that LeuT harbours a single, centrally located, high-affinity substrate-binding site and that transport is well described by a simple, single-substrate kinetic mechanism.

  12. Focused helium-ion beam irradiation effects on electrical transport properties of few-layer WSe2: Enabling nanoscale direct write homo-junctions

    SciTech Connect

    Stanford, Michael; Noh, Joo Hyon; Koehler, Michael R.; Mandrus, David G.; Duscher, Gerd; Rondinone, Adam Justin; Ivanov, Ilia N.; Ward, Thomas Zac; Rack, Philip D.; Pudasaini, Pushpa Raj; Belianinov, Alex; Cross, Nicholas

    2016-06-06

    Atomically thin transition metal dichalcogenides (TMDs) are currently receiving significant attention due to their promising opto-electronic properties. Tuning optical and electrical properties of mono and few-layer TMDs, such as tungsten diselenide (WSe2), by controlling the defects, is an intriguing opportunity to synthesize next generation two dimensional material opto-electronic devices. Here, we report the effects of focused helium ion beam irradiation on the structural, optical and electrical properties of few-layer WSe2, via high resolution scanning transmission electron microscopy, Raman spectroscopy, and electrical transport measurements. By controlling the ion irradiation dose, we selectively introduce precise defects in few-layer WSe2 thereby locally tuning the resistivity and transport properties of the material. Hole transport in the few layer WSe2 is degraded more severely relative to electron transport after helium ion irradiation. Moreover, by selectively exposing material with the ion beam, we demonstrate a simple yet highly tunable method to create lateral homo-junctions in few layer WSe2 flakes, which constitutes an important advance towards two dimensional opto-electronic devices.

  13. Focused helium-ion beam irradiation effects on electrical transport properties of few-layer WSe2: enabling nanoscale direct write homo-junctions

    NASA Astrophysics Data System (ADS)

    Stanford, Michael G.; Pudasaini, Pushpa Raj; Belianinov, Alex; Cross, Nicholas; Noh, Joo Hyon; Koehler, Michael R.; Mandrus, David G.; Duscher, Gerd; Rondinone, Adam J.; Ivanov, Ilia N.; Ward, T. Zac; Rack, Philip D.

    2016-06-01

    Atomically thin transition metal dichalcogenides (TMDs) are currently receiving significant attention due to their promising opto-electronic properties. Tuning optical and electrical properties of mono and few-layer TMDs, such as tungsten diselenide (WSe2), by controlling the defects, is an intriguing opportunity to synthesize next generation two dimensional material opto-electronic devices. Here, we report the effects of focused helium ion beam irradiation on the structural, optical and electrical properties of few-layer WSe2, via high resolution scanning transmission electron microscopy, Raman spectroscopy, and electrical transport measurements. By controlling the ion irradiation dose, we selectively introduce precise defects in few-layer WSe2 thereby locally tuning the resistivity and transport properties of the material. Hole transport in the few layer WSe2 is degraded more severely relative to electron transport after helium ion irradiation. Furthermore, by selectively exposing material with the ion beam, we demonstrate a simple yet highly tunable method to create lateral homo-junctions in few layer WSe2 flakes, which constitutes an important advance towards two dimensional opto-electronic devices.

  14. Focused helium-ion beam irradiation effects on electrical transport properties of few-layer WSe2: Enabling nanoscale direct write homo-junctions

    DOE PAGES

    Stanford, Michael; Noh, Joo Hyon; Koehler, Michael R.; ...

    2016-06-06

    Atomically thin transition metal dichalcogenides (TMDs) are currently receiving significant attention due to their promising opto-electronic properties. Tuning optical and electrical properties of mono and few-layer TMDs, such as tungsten diselenide (WSe2), by controlling the defects, is an intriguing opportunity to synthesize next generation two dimensional material opto-electronic devices. Here, we report the effects of focused helium ion beam irradiation on the structural, optical and electrical properties of few-layer WSe2, via high resolution scanning transmission electron microscopy, Raman spectroscopy, and electrical transport measurements. By controlling the ion irradiation dose, we selectively introduce precise defects in few-layer WSe2 thereby locally tuningmore » the resistivity and transport properties of the material. Hole transport in the few layer WSe2 is degraded more severely relative to electron transport after helium ion irradiation. Moreover, by selectively exposing material with the ion beam, we demonstrate a simple yet highly tunable method to create lateral homo-junctions in few layer WSe2 flakes, which constitutes an important advance towards two dimensional opto-electronic devices.« less

  15. Altered Expression of Genes Encoding Neurotransmitter Receptors in GnRH Neurons of Proestrous Mice

    PubMed Central

    Vastagh, Csaba; Rodolosse, Annie; Solymosi, Norbert; Liposits, Zsolt

    2016-01-01

    Gonadotropin-releasing hormone (GnRH) neurons play a key role in the central regulation of reproduction. In proestrous female mice, estradiol triggers the pre-ovulatory GnRH surge, however, its impact on the expression of neurotransmitter receptor genes in GnRH neurons has not been explored yet. We hypothesized that proestrus is accompanied by substantial changes in the expression profile of genes coding for neurotransmitter receptors in GnRH neurons. We compared the transcriptome of GnRH neurons obtained from intact, proestrous, and metestrous female GnRH-GFP transgenic mice, respectively. About 1500 individual GnRH neurons were sampled from both groups and their transcriptome was analyzed using microarray hybridization and real-time PCR. In this study, changes in mRNA expression of genes involved in neurotransmitter signaling were investigated. Differential gene expression was most apparent in GABA-ergic (Gabbr1, Gabra3, Gabrb3, Gabrb2, Gabrg2), glutamatergic (Gria1, Gria2, Grin1, Grin3a, Grm1, Slc17a6), cholinergic (Chrnb2, Chrm4) and dopaminergic (Drd3, Drd4), adrenergic (Adra1b, Adra2a, Adra2c), adenosinergic (Adora2a, Adora2b), glycinergic (Glra), purinergic (P2rx7), and serotonergic (Htr1b) receptors. In concert with these events, expression of genes in the signaling pathways downstream to the receptors, i.e., G-proteins (Gnai1, Gnai2, Gnas), adenylate-cyclases (Adcy3, Adcy5), protein kinase A (Prkaca, Prkacb) protein kinase C (Prkca) and certain transporters (Slc1a4, Slc17a6, Slc6a17) were also changed. The marked differences found in the expression of genes involved in neurotransmitter signaling of GnRH neurons at pro- and metestrous stages of the ovarian cycle indicate the differential contribution of these neurotransmitter systems to the induction of the pre-ovulatory GnRH surge, the known prerequisite of the subsequent hormonal cascade inducing ovulation. PMID:27774052

  16. Infrared photodissociation spectroscopy of protonated neurotransmitters in the gas phase

    NASA Astrophysics Data System (ADS)

    MacLeod, N. A.; Simons, J. P.

    2007-03-01

    Protonated neurotransmitters have been produced in the gas phase via a novel photochemical scheme: complexes of the species of interest, 1-phenylethylamine, 2-amino-1-phenylethanol and the diastereo-isomers, ephedrine and pseudoephedrine, with a suitable proton donor, phenol (or indole), are produced in a supersonic expansion and ionized by resonant two photon ionization of the donor. Efficient proton transfer generates the protonated neurotransmitters, complexed to a phenoxy radical. Absorption of infrared radiation, and subsequent evaporation of the phenoxy tag, coupled with time of flight mass spectrometry, provides vibrational spectra of the protonated (and also hydrated) complexes for comparison with the results of quantum chemical computation. Comparison with the conformational structures of the neutral neurotransmitters (established previously) reveals the effect of protonation on their structure. The photochemical proton transfer strategy allows spectra to be recorded from individual laser shots and their quality compares favourably with that obtained using electro-spray or matrix assisted laser desorption ion sources.

  17. THE PURINERGIC NEUROTRANSMITTER REVISITED: A SINGLE SUBSTANCE OR MULTIPLE PLAYERS?

    PubMed Central

    Mutafova-Yambolieva, Violeta N.; Durnin, Leonie

    2014-01-01

    The past half century has witnessed tremendous advances in our understanding of extracellular purinergic signaling pathways. Purinergic neurotransmission, in particular, has emerged as a key contributor in the efficient control mechanisms in the nervous system. The identity of the purine neurotransmitter, however, remains controversial. Identifying it is difficult because purines are present in all cell types, have a large variety of cell sources, and are released via numerous pathways. Moreover, studies on purinergic neurotransmission have relied heavily on indirect measurements of integrated postjunctional responses that do not provide direct information for neurotransmitter identity. This paper discusses experimental support for adenosine 5′-triphosphate (ATP) as a neurotransmitter and recent evidence for possible contribution of other purines, in addition to or instead of ATP, in chemical neurotransmission in the peripheral, enteric and central nervous systems. Sites of release and action of purines in model systems such as vas deferens, blood vessels, urinary bladder and chromaffin cells are discussed. This is preceded by a brief discussion of studies demonstrating storage of purines in synaptic vesicles. We examine recent evidence for cell type targets (e.g., smooth muscle cells, interstitial cells, neurons and glia) for purine neurotransmitters in different systems. This is followed by brief discussion of mechanisms of terminating the action of purine neurotransmitters, including extracellular nucleotide hydrolysis and possible salvage and reuptake in the cell. The significance of direct neurotransmitter release measurements is highlighted. Possibilities for involvement of multiple purines (e.g., ATP, ADP, NAD+, ADP-ribose, adenosine, and diadenosine polyphosphates) in neurotransmission are considered throughout. PMID:24887688

  18. Regulation of cognition and symptoms of psychosis: focus on GABA(A) receptors and glycine transporter 1.

    PubMed

    Möhler, Hanns; Rudolph, Uwe; Boison, Detlev; Singer, Philipp; Feldon, Joram; Yee, Benjamin K

    2008-07-01

    Adaptive purposeful behaviour depends on appropriate modifications of synaptic connectivity that incorporate an organism's past experience. At least some forms of such synaptic plasticity are believed to be mediated by NMDA receptors (NMDARs). Complementary interaction with inhibitory neurotransmission mediated by GABA(A) receptors, and upstream control of the excitability of NMDARs by glycine availability can greatly influence the efficacy of NMDAR mediated neuroplasticity, and thereby exert significant effects on cognition. Memory, selective attention or sensorimotor gating functions can be modified in mice with a reduction of alpha(5)GABA(A) receptors in the hippocampus or a selective deletion of glycine transporter 1 (GlyT1) in the forebrain. Both genetic manipulations altered the formation or persistence of associative links leading to distinct phenotypes on trace conditioning, extinction learning, latent inhibition, working memory, and object recognition. Behavioural assays of latent inhibition, prepulse inhibition, working memory, and sensitivity to psychostimulants in particular suggest that alpha(3) and alpha(5) subunit-containing GABA(A) receptors as well as GlyT1 are potential sites for ameliorating psychotic-like behaviour. Taken together, these results qualify distinct GABA-A receptor subtypes and GlyT1 as molecular targets for the development of a new pharmacology in the treatment of cognitive decline and psychotic symptoms.

  19. Benzodiazepine receptor and neurotransmitter studies in the brain of suicides

    SciTech Connect

    Manchon, M.; Kopp, N.; Rouzioux, J.J.; Lecestre, D.; Deluermoz, S.; Miachon, S.

    1987-12-14

    The characteristics of benzodiazepine binding sites were studied on frozen sections of hippocampus of 7 suicides and 5 controls subjects, using biochemical and autoradiographic techniques. /sup 3/H flunitrazepam was used as ligand, clonazepam and CL 218,872 as displacing agents. Some neurotransmitters or their derivatives were evaluated quantitatively in parallel in the hippocampal tissue by liquid chromatography. The authors observed mainly an increase in the Ki of CL 218,872 subtype I binding sites in suicides, and an increase in % of type I binding sites. Among neurotransmitters, only norepinephrine differed significantly between controls and suicides. 36 references, 3 figures, 1 table.

  20. Changes in cerebral neurotransmitters and metabolites induced by acute donepezil and memantine administrations: a microdialysis study.

    PubMed

    Shearman, E; Rossi, S; Szasz, B; Juranyi, Z; Fallon, S; Pomara, N; Sershen, H; Lajtha, A

    2006-03-31

    Cholinesterase inhibitors including donepezil, rivastigmine, and galantamine and the N-methyl-D-aspartate (NMDA) antagonist, memantine are the medications currently approved for the treatment of Alzheimer's disease (AD). In addition to their beneficial effects on cognitive and functional domains typically disrupted in AD, these agents have also been shown to slow down the emergence of behavioral and psychotic symptoms associated with this disease. However, the underlying mechanisms for these therapeutic effects remain poorly understood and could involve effects of these medications on non-cholinergic or non-glutamatergic neurotransmitter systems respectively. These considerations prompted us to initiate a series of investigations to examine the acute and chronic effects of donepezil (Aricept (+/-)-2,3-dihydro-5,6-dimethoxy-2-[[1-(phenylmethyl)-4-piperidinyl]methyl]-1H-inden-1-1 hydrochloride and memantine (1-amino-3,5-dimethyladamantane hydrochloride C12H21N.HCl)). The present study focuses on the acute effects of donepezil and memantine on brain extracellular levels of acetylcholine, dopamine, serotonin, norepinephrine and their metabolites. We assayed changes in the ventral and dorsal hippocampus and the prefrontal and medial temporal cortex by microdialysis. Memantine resulted in significant increases in extracellular dopamine (DA), norepinephrine (NE), and their metabolites, in the cortical regions, and in a reduction of DA in the hippocampus. Donepezil produced an increase in extracellular DA in the cortex and in the dorsal hippocampus. Norepinephrine increased in the cortex; with donepezil it increased in the dorsal hippocampus and the medial temporal cortex, and decreased in the ventral hippocampus. Interestingly both compounds decreased extracellular serotonin (5HT) levels. The metabolites of the neurotransmitters were increased in most areas. We also found an increase in extracellular acetylcholine (ACh) by memantine in the nucleus accumbens and the

  1. Ricardo Miledi and the calcium hypothesis of neurotransmitter release.

    PubMed

    Jeng, Jade-Ming

    2002-01-01

    Ricardo Miledi has made significant contributions to our basic understanding of how synapses work. Here I discuss aspects of Miledi's research that helped to establish the requirement of presynaptic calcium for neurotransmitter release, from his earliest scientific studies to his classic experiments in the squid giant synapse.

  2. Construction of cell-based neurotransmitter fluorescently engineered reporters (CNiFERs) for optical detection of neurotransmitters in vivo

    PubMed Central

    Lacin, Emre; Muller, Arnaud; Fernando, Marian; Kleinfeld, David; Slesinger, Paul A

    2016-01-01

    Cell-based neurotransmitter fluorescent engineered reporters (CNiFERs) provide a new tool for neuroscientists to optically detect the release of neurotransmitters in the brain in vivo. A specific CNiFER is created from a human embryonic kidney cell that stably expresses a specific G protein-coupled receptor, which couples to Gq/11 G proteins, and a FRET-based Ca2+-detector, TN-XXL – activation of the receptor leads to an increase in the FRET signal. Because a CNiFER clone utilizes the native receptor for a particular neurotransmitter (e.g. D2R for dopamine), it has nanomolar sensitivity and a temporal response of seconds. CNiFERs are directly implanted into the brain, enabling them to sense neurotransmitter release with a spatial resolution of less than one hundred micrometers, making them ideal to measure volume transmission in vivo. CNiFERs can also be used to screen other drugs for potential cross-reactivity in vivo. We recently expanded the family of CNiFERs to include GPCRs that couple to Gi/o G proteins. CNiFERs are available for detecting acetylcholine (ACh), dopamine (DA) and norepinephrine (NE). Given that any GPCR can be used to create a novel CNiFER and that there are approximately 800 GPCRs in the human genome, we describe here the general procedure to design, realize, and test any type of CNiFER. PMID:27214050

  3. Role of neurotransmitters in palate development and teratologic implications.

    PubMed

    Zimmerman, E F

    1985-01-01

    It is hypothesized that neuropharmacologic agents are more teratogenic to humans. Since many neuropharmacologic agents function through neurotransmitter mechanisms, then neurotransmitters should function to regulate embryonic development. Evidence has been obtained that neurotransmitters do indeed function as biological signals in palate development. It has been shown that palate reorientation is modulated by neurotransmitters with a wide range of diversity, similar to the CNS. Thus serotonin and acetylcholine stimulate and GABA inhibits the reorientation process. Spatial diversity is also observed: serotonin functions at the anterior and acetylcholine at the posterior end, and GABA functions more efficiently at either end in different inbred strains. Many criteria for functioning neurotransmitters have been obtained. Both serotonin and GABA have been measured in the palate and developmental changes observed. Physiologic responses to serotonin have been monitored. Serotonin has been shown to stimulate palate cell motility as well as protein carboxyl methylation and cyclic GMP. The serotonin effects on protein carboxyl methylation and cyclic GMP could function to stimulate palate reorientation by modulating cell contractility and protein secretion. Further support for the hypothesis that neuropharmacologic agents could be teratogenic by perturbation of neurotransmitter mechanisms comes from studying GABA and diazepam. Evidence has been obtained that diazepam induces cleft palate by mimicking GABA in a functional GABAergic system in palate development. A significant finding is that genetic differences in both diazepam teratogenesis and in a GABAergic system have been observed. Comparing the SWV and AJ strains, the SWV mouse showed (1) a greater sensitivity to diazepam-induced cleft palate, (2) a greater sensitivity to GABA and diazepam inhibition of palate reorientation in embryo culture, (3) a greater concentration of palatal GABA and (4) a more efficient GABA

  4. Deletion of mouse FXR gene disturbs multiple neurotransmitter systems and alters neurobehavior

    PubMed Central

    Huang, Fei; Wang, Tingting; Lan, Yunyi; Yang, Li; Pan, Weihong; Zhu, Yonghui; Lv, Boyang; Wei, Yuting; Shi, Hailian; Wu, Hui; Zhang, Beibei; Wang, Jie; Duan, Xiaofeng; Hu, Zhibi; Wu, Xiaojun

    2015-01-01

    Farnesoid X receptor (FXR) is a nuclear hormone receptor involved in bile acid synthesis and homeostasis. Dysfunction of FXR is involved in cholestasis and atherosclerosis. FXR is prevalent in liver, gallbladder, and intestine, but it is not yet clear whether it modulates neurobehavior. In the current study, we tested the hypothesis that mouse FXR deficiency affects a specific subset of neurotransmitters and results in an unique behavioral phenotype. The FXR knockout mice showed less depressive-like and anxiety-related behavior, but increased motor activity. They had impaired memory and reduced motor coordination. There were changes of glutamatergic, GABAergic, serotoninergic, and norepinephrinergic neurotransmission in either hippocampus or cerebellum. FXR deletion decreased the amount of the GABA synthesis enzyme GAD65 in hippocampus but increased GABA transporter GAT1 in cerebral cortex. FXR deletion increased serum concentrations of many bile acids, including taurodehydrocholic acid, taurocholic acid, deoxycholic acid (DCA), glycocholic acid (GCA), tauro-α-muricholic acid, tauro-ω-muricholic acid, and hyodeoxycholic acid (HDCA). There were also changes in brain concentrations of taurocholic acid, taurodehydrocholic acid, tauro-ω-muricholic acid, tauro-β-muricholic acid, deoxycholic acid, and lithocholic acid (LCA). Taken together, the results from studies with FXR knockout mice suggest that FXR contributes to the homeostasis of multiple neurotransmitter systems in different brain regions and modulates neurobehavior. The effect appears to be at least partially mediated by bile acids that are known to cross the blood-brain barrier (BBB) inducing potential neurotoxicity. PMID:25870546

  5. Conformational dynamics of a neurotransmitter:sodium symporter in a lipid bilayer.

    PubMed

    Adhikary, Suraj; Deredge, Daniel J; Nagarajan, Anu; Forrest, Lucy R; Wintrode, Patrick L; Singh, Satinder K

    2017-03-07

    Neurotransmitter:sodium symporters (NSSs) are integral membrane proteins responsible for the sodium-dependent reuptake of small-molecule neurotransmitters from the synaptic cleft. The symporters for the biogenic amines serotonin (SERT), dopamine (DAT), and norepinephrine (NET) are targets of multiple psychoactive agents, and their dysfunction has been implicated in numerous neuropsychiatric ailments. LeuT, a thermostable eubacterial NSS homolog, has been exploited as a model protein for NSS members to canvass the conformational mechanism of transport with a combination of X-ray crystallography, cysteine accessibility, and solution spectroscopy. Despite yielding remarkable insights, these studies have primarily been conducted with protein in the detergent-solubilized state rather than embedded in a membrane mimic. In addition, solution spectroscopy has required site-specific labeling of nonnative cysteines, a labor-intensive process occasionally resulting in diminished transport and/or binding activity. Here, we overcome these limitations by reconstituting unlabeled LeuT in phospholipid bilayer nanodiscs, subjecting them to hydrogen-deuterium exchange coupled with mass spectrometry (HDX-MS), and facilitating interpretation of the data with molecular dynamics simulations. The data point to changes of accessibility and dynamics of structural elements previously implicated in the transport mechanism, in particular transmembrane helices (TMs) 1a and 7 as well as extracellular loops (ELs) 2 and 4. The results therefore illuminate the value of this strategy for interrogating the conformational mechanism of the more clinically significant mammalian membrane proteins including SERT and DAT, neither of which tolerates complete removal of endogenous cysteines, and whose activity is heavily influenced by neighboring lipids.

  6. Dynamic Control of Neurotransmitter Release by Presynaptic Potential

    PubMed Central

    Zbili, Mickael; Rama, Sylvain; Debanne, Dominique

    2016-01-01

    Action potentials (APs) in the mammalian brain are thought to represent the smallest unit of information transmitted by neurons to their postsynaptic targets. According to this view, neuronal signaling is all-or-none or digital. Increasing evidence suggests, however, that subthreshold changes in presynaptic membrane potential before triggering the spike also determines spike-evoked release of neurotransmitter. We discuss here how analog changes in presynaptic voltage may regulate spike-evoked release of neurotransmitter through the modulation of biophysical state of voltage-gated potassium, calcium and sodium channels in the presynaptic compartment. The contribution of this regulation has been greatly underestimated and we discuss the impact for information processing in neuronal circuits. PMID:27994539

  7. Imaging Mass Spectrometric Analysis of Neurotransmitters: A Review

    PubMed Central

    Romero-Perez, Gustavo A.; Takei, Shiro; Yao, Ikuko

    2014-01-01

    Imaging mass spectrometry (IMS) is a toolbox of versatile techniques that enable us to investigate analytes in samples at molecular level. In recent years, IMS, and especially matrix-assisted laser desorption/ionisation (MALDI), has been used to visualise a wide range of metabolites in biological samples. Simultaneous visualisation of the spatial distribution of metabolites in a single sample with little tissue disruption can be considered as one important advantage of MALDI over other techniques. However, several technical hurdles including low concentrations and rapid degradation rates of small molecule metabolites, matrix interference of signals and poor ionisation, need to be addressed before MALDI can be considered as a reliable tool for the analysis of metabolites such as neurotransmitters in brain tissues from different sources including humans. In the present review we will briefly describe current MALDI IMS techniques used to study neurotransmitters and discuss their current status, challenges, as well as future prospects. PMID:26819893

  8. Alterations in Brain Monoamine Neurotransmitter Release at High Pressure

    DTIC Science & Technology

    1989-01-01

    exposure results from a general imbalance of encephalopathies. Parkinson’s Syndrome, MPTP the three monoamine neurotransmitter systems toxicity . or...the [3 H]monoamines by Dopamine release, on the other hand, was reduced synaptosomes isolated from the CNS. 5-A n 4 A Pn5 p<.05 0.05 LI * 4- U) 4...Lffect of’ pressure of 3.4-miethylenledioxy-miethamiiphetamnine ( MDMA ) and re- on the release of radioaetive glycine and (IABA from spinal lated

  9. Profiling neurotransmitter receptor expression in the Ambystoma mexicanum brain.

    PubMed

    Reyes-Ruiz, Jorge Mauricio; Limon, Agenor; Korn, Matthew J; Nakamura, Paul A; Shirkey, Nicole J; Wong, Jamie K; Miledi, Ricardo

    2013-03-22

    Ability to regenerate limbs and central nervous system (CNS) is unique to few vertebrates, most notably the axolotl (Ambystoma sp.). However, despite the fact the neurotransmitter receptors are involved in axonal regeneration, little is known regarding its expression profile. In this project, RT-PCR and qPCR were performed to gain insight into the neurotransmitter receptors present in Ambystoma. Its functional ability was studied by expressing axolotl receptors in Xenopus laevis oocytes by either injection of mRNA or by direct microtransplantation of brain membranes. Oocytes injected with axolotl mRNA expressed ionotropic receptors activated by GABA, aspartate+glycine and kainate, as well as metabotropic receptors activated by acetylcholine and glutamate. Interestingly, we did not see responses following the application of serotonin. Membranes from the axolotl brain were efficiently microtransplanted into Xenopus oocytes and two types of native GABA receptors that differed in the temporal course of their responses and affinities to GABA were observed. Results of this study are necessary for further characterization of axolotl neurotransmitter receptors and may be useful for guiding experiments aimed at understanding activity-dependant limb and CNS regeneration.

  10. Electrochemical techniques for subsecond neurotransmitter detection in live rodents.

    PubMed

    Hascup, Kevin N; Hascup, Erin R

    2014-08-01

    Alterations in neurotransmission have been implicated in numerous neurodegenerative and neuropsychiatric disorders, including Alzheimer disease, Parkinson disease, epilepsy, and schizophrenia. Unfortunately, few techniques support the measurement of real-time changes in neurotransmitter levels over multiple days, as is essential for ethologic and pharmacodynamic testing. Microdialysis is commonly used for these research paradigms, but its poor temporal and spatial resolution make this technique inadequate for measuring the rapid dynamics (milliseconds to seconds) of fast signaling neurotransmitters, such as glutamate and acetylcholine. Enzymatic microelectrode arrays (biosensors) coupled with electrochemical recording techniques have demonstrated fast temporal resolution (less than 1 s), excellent spatial resolution (micron-scale), low detection limits (≤200 nM), and minimal damage (50 to 100 μm) to surrounding brain tissue. Here we discuss the benefits, methods, and animal welfare considerations of using platinum microelectrodes on a ceramic substrate for enzyme-based electrochemical recording techniques for real-time in vivo neurotransmitter recordings in both anesthetized and awake, freely moving rodents.

  11. Neurotransmitters act as paracrine signals to regulate insulin secretion from the human pancreatic islet.

    PubMed

    Rodriguez-Diaz, Rayner; Menegaz, Danusa; Caicedo, Alejandro

    2014-08-15

    In this symposium review we discuss the role of neurotransmitters as paracrine signals that regulate pancreatic islet function. A large number of neurotransmitters and their receptors has been identified in the islet, but relatively little is known about their involvement in islet biology. Interestingly, neurotransmitters initially thought to be present in autonomic axons innervating the islet are also present in endocrine cells of the human islet. These neurotransmitters can thus be released as paracrine signals to help control hormone release. Here we propose that the role of neurotransmitters may extend beyond controlling endocrine cell function to work as signals modulating vascular flow and immune responses within the islet.

  12. Unsaturated Analogues of the Neurotransmitter GABA: trans-4-Aminocrotonic, cis-4-Aminocrotonic and 4-Aminotetrolic Acids.

    PubMed

    Johnston, Graham A R

    2016-03-01

    Analogues of the neurotransmitter GABA containing unsaturated bonds are restricted in the conformations they can attain. This review traces three such analogues from their synthesis to their use as neurochemicals. trans-4-Aminocrotonic acid was the first conformationally restricted analogue to be extensively studied. It acts like GABA across a range of macromolecules from receptors to transporters. It acts similarly to GABA on ionotropic receptors. cis-4-Aminocrotonic acid selectively activates bicuculline-insensitive GABAC receptors. 4-Aminotetrolic acid, containing a triple bond, activates bicuculline-sensitive GABAA receptors. These findings indicate that GABA activates GABAA receptors in extended conformations and GABAC receptors in folded conformations. These and related analogues are important for the molecular modelling of ionotropic GABA receptors and to the development of new agents acting selectively on these receptors.

  13. Recent advances in transport of water-soluble vitamins in organs of the digestive system: a focus on the colon and the pancreas

    PubMed Central

    2013-01-01

    This review focuses on recent advances in our understanding of the mechanisms and regulation of water-soluble vitamin (WSV) transport in the large intestine and pancreas, two important organs of the digestive system that have only recently received their fair share of attention. WSV, a group of structurally unrelated compounds, are essential for normal cell function and development and, thus, for overall health and survival of the organism. Humans cannot synthesize WSV endogenously; rather, WSV are obtained from exogenous sources via intestinal absorption. The intestine is exposed to two sources of WSV: a dietary source and a bacterial source (i.e., WSV generated by the large intestinal microbiota). Contribution of the latter source to human nutrition/health has been a subject of debate and doubt, mostly based on the absence of specialized systems for efficient uptake of WSV in the large intestine. However, recent studies utilizing a variety of human and animal colon preparations clearly demonstrate that such systems do exist in the large intestine. This has provided strong support for the idea that the microbiota-generated WSV are of nutritional value to the host, and especially to the nutritional needs of the local colonocytes and their health. In the pancreas, WSV are essential for normal metabolic activities of all its cell types and for its exocrine and endocrine functions. Significant progress has also been made in understanding the mechanisms involved in the uptake of WSV and the effect of chronic alcohol exposure on the uptake processes. PMID:23989008

  14. The importance of synapsin I and II for neurotransmitter levels and vesicular storage in cholinergic, glutamatergic and GABAergic nerve terminals.

    PubMed

    Bogen, Inger Lise; Haug, Kristin Huse; Roberg, Bjørg; Fonnum, Frode; Walaas, S Ivar

    2009-01-01

    The aim of this study was to examine the importance of the vesicle-associated synapsin I and II phosphoproteins for the accumulation of neurotransmitters in central cholinergic as compared to central glutamatergic and GABAergic nerve terminals. In brain homogenate samples from mice devoid of synapsin I and II, the levels of vesicular transporters for glutamate (VGLUT1-2) and GABA (VGAT) were decreased by 35-40% in striatum and cortex, while no change was apparent for the vesicular acetylcholine transporter (VAChT). The severe decrease in the levels of amino acid vesicular transporters caused only minor changes in the concentrations of the respective neurotransmitters in homogenates of the three selected brain areas from synapsin I- and II-deficient mice. However, when measured in a crude vesicular fraction, the concentrations of glutamate and GABA were decreased by 48-60% in synapsin-deficient mice, with a similar decrease in the levels of VGLUT1, VGLUT2 and VGAT. In comparison, the concentration of acetylcholine and the level of VAChT were not significantly different from wild-type in the vesicular fraction. No changes were seen in the activity of specific enzymes involved in the synthesis of acetylcholine, glutamate or GABA, however, immunoblotting indicated a decrease in the protein level of glutamic acid decarboxylase, isoform 65 (GAD(65)). In conclusion, the results indicate that neurotransmitter regulation in central cholinergic synapses may be less dependent on synapsin I and II compared to the marked alterations seen in the glutamatergic and GABAergic synapses.

  15. Stress, neurotransmitters, corticosterone and body-brain integration.

    PubMed

    Mora, Francisco; Segovia, Gregorio; Del Arco, Alberto; de Blas, Marta; Garrido, Pedro

    2012-10-02

    Stress can be defined as a brain-body reaction towards stimuli arising from the environment or from internal cues that are interpreted as a disruption of homeostasis. The organization of the response to a stressful situation involves not only the activity of different types of neurotransmitter systems in several areas of the limbic system, but also the response of neurons in these areas to several other chemicals and hormones, chiefly glucocorticoids, released from peripheral organs and glands. Thus, stress is probably the process through which body-brain integration plays a major role. Here we review first the responses to an acute stress in terms of neurotransmitters such as dopamine, acetylcholine, glutamate and GABA in areas of the brain involved in the regulation of stress responses. These areas include the prefrontal cortex, amygdala, hippocampus and nucleus accumbens and the interaction among those areas. Then, we consider the role of glucocorticoids and review some recent data about the interaction of these steroids with several neurotransmitters in those same areas of the brain. Also the actions of other substances (neuromodulators) released from peripheral organs such as the pancreas, liver or gonads (insulin, IGF-1, estrogens) are reviewed. The role of an environmental enrichment on these same responses is also discussed. Finally a section is devoted to put into perspective all these environmental-brain-body-brain interactions during stress and their consequences on aging. It is concluded that the integrative perspective framed in this review is relevant for better understanding of how the organism responds to stressful challenges and how this can be modified through different environmental conditions during the process of aging. This article is part of a Special Issue entitled: Brain Integration.

  16. Neurotransmitters in the Gas Phase: La-Mb Studies

    NASA Astrophysics Data System (ADS)

    Cabezas, C.; Mata, S.; López, J. C.; Alonso, J. L.

    2011-06-01

    LA-MB-FTMW spectroscopy combines laser ablation with Fourier transform microwave spectroscopy in supersonic jets overcoming the problems of thermal decomposition associated with conventional heating methods. We present here the results on LA-MB-FTMW studies of some neurotransmitters. Six conformers of dopamine, four of adrenaline, five of noradrenaline and three conformers of serotonin have been characterized in the gas phase. The rotational and nuclear quadrupole coupling constants extracted from the analysis of the rotational spectrum are directly compared with those predicted by ab initio methods to achieve the conclusive identification of different conformers and the experimental characterization of the intramolecular forces at play which control conformational preferences.

  17. Name that neurotransmitter: using music to teach psychopharmacology concepts.

    PubMed

    Hermanns, Melinda; Lilly, Mary LuAnne; Wilson, Kathy; Russell, Nathan Andrew

    2012-09-01

    The purpose of this article is to discuss the use of music (i.e., two original songs, "Neurotransmitter Twitter" and "Parkinson's Shuffle") to teach aspects of psychopharmacology to students in the course Psychiatric/Mental Health Nursing. Songs were incorporated in both the clinical and classroom settings. This innovative teaching method allowed students the opportunity to revisit the information through multiple exposures of the content for reinforcement and enhancement of student learning in a fun, creative approach. Brain-based research will be discussed, along with the process of development.

  18. Carbon Nanotube-based microelectrodes for enhanced detection of neurotransmitters

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher B.

    Fast-scan cyclic voltammetry (FSCV) is one of the common techniques used for rapid measurement of neurotransmitters in vivo. Carbon-fiber microelectrodes (CFMEs) are typically used for neurotransmitter detection because of sub-second measurement capabilities, ability to measure changes in neurotransmitter concentration during neurotransmission, and the small size electrode diameter, which limits the amount of damage caused to tissue. Cylinder CFMEs, typically 50 -- 100 microm long, are commonly used for in vivo experiments because the electrode sensitivity is directly related to the electrode surface area. However the length of the electrode can limit the spatial resolution of neurotransmitter detection, which can restrict experiments in Drosophila and other small model systems. In addition, the electrode sensitivity toward dopamine and serotonin detection drops significantly for measurements at rates faster than 10 Hz, limiting the temporal resolution of CFMEs. While the use of FSCV at carbon-fiber microelectrodes has led to substantial strides in our understanding of neurotransmission, techniques that expand the capabilities of CFMEs are crucial to fully maximize the potential uses of FSCV. This dissertation introduces new methods to integrate carbon nanotubes (CNT) into microelectrodes and discusses the electrochemical enhancements of these CNT-microelectrodes. The electrodes are specifically designed with simple fabrication procedures so that highly specialized equipment is not necessary, and they utilize commercially available materials so that the electrodes could be easily integrated into existing systems. The electrochemical properties of CNT modified CFMEs are characterized using FSCV and the effect of CNT functionalization on these properties is explored in Chapter 2. For example, CFME modification using carboxylic acid functionalized CNTs yield about a 6-fold increase in dopamine oxidation current, but modification with octadecylamine CNTs results in a

  19. Beta-amyloid peptides undergo regulated co-secretion with neuropeptide and catecholamine neurotransmitters.

    PubMed

    Toneff, Thomas; Funkelstein, Lydiane; Mosier, Charles; Abagyan, Armen; Ziegler, Michael; Hook, Vivian

    2013-08-01

    Beta-amyloid (Aβ) peptides are secreted from neurons, resulting in extracellular accumulation of Aβ and neurodegeneration of Alzheimer's disease. Because neuronal secretion is fundamental for the release of neurotransmitters, this study assessed the hypothesis that Aβ undergoes co-release with neurotransmitters. Model neuronal-like chromaffin cells were investigated, and results illustrate regulated, co-secretion of Aβ(1-40) and Aβ(1-42) with peptide neurotransmitters (galanin, enkephalin, and NPY) and catecholamine neurotransmitters (dopamine, norepinephrine, and epinephrine). Regulated secretion from chromaffin cells was stimulated by KCl depolarization and nicotine. Forskolin, stimulating cAMP, also induced co-secretion of Aβ peptides with peptide and catecholamine neurotransmitters. These data suggested the co-localization of Aβ with neurotransmitters in dense core secretory vesicles (DCSV) that store and secrete such chemical messengers. Indeed, Aβ was demonstrated to be present in DCSV with neuropeptide and catecholamine transmitters. Furthermore, the DCSV organelle contains APP and its processing proteases, β- and γ-secretases, that are necessary for production of Aβ. Thus, Aβ can be generated in neurotransmitter-containing DCSV. Human IMR32 neuroblastoma cells also displayed regulated secretion of Aβ(1-40) and Aβ(1-42) with the galanin neurotransmitter. These findings illustrate that Aβ peptides are present in neurotransmitter-containing DCSV, and undergo co-secretion with neuropeptide and catecholamine neurotransmitters that regulate brain functions.

  20. Substrate-induced Unlocking of the Inner Gate Determines the Catalytic Efficiency of a Neurotransmitter:Sodium Symporter*

    PubMed Central

    Billesbølle, Christian B.; Krüger, Mie B.; Shi, Lei; Quick, Matthias; Li, Zheng; Stolzenberg, Sebastian; Kniazeff, Julie; Gotfryd, Kamil; Mortensen, Jonas S.; Javitch, Jonathan A.; Weinstein, Harel; Loland, Claus J.; Gether, Ulrik

    2015-01-01

    Neurotransmitter:sodium symporters (NSSs) mediate reuptake of neurotransmitters from the synaptic cleft and are targets for several therapeutics and psychostimulants. The prokaryotic NSS homologue, LeuT, represents a principal structural model for Na+-coupled transport catalyzed by these proteins. Here, we used site-directed fluorescence quenching spectroscopy to identify in LeuT a substrate-induced conformational rearrangement at the inner gate conceivably leading to formation of a structural intermediate preceding transition to the inward-open conformation. The substrate-induced, Na+-dependent change required an intact primary substrate-binding site and involved increased water exposure of the cytoplasmic end of transmembrane segment 5. The findings were supported by simulations predicting disruption of an intracellular interaction network leading to a discrete rotation of transmembrane segment 5 and the adjacent intracellular loop 2. The magnitude of the spectroscopic response correlated inversely with the transport rate for different substrates, suggesting that stability of the intermediate represents an unrecognized rate-limiting barrier in the NSS transport mechanism. PMID:26363074

  1. Substrate-induced unlocking of the inner gate determines the catalytic efficiency of a neurotransmitter:sodium symporter.

    PubMed

    Billesbølle, Christian B; Krüger, Mie B; Shi, Lei; Quick, Matthias; Li, Zheng; Stolzenberg, Sebastian; Kniazeff, Julie; Gotfryd, Kamil; Mortensen, Jonas S; Javitch, Jonathan A; Weinstein, Harel; Loland, Claus J; Gether, Ulrik

    2015-10-30

    Neurotransmitter:sodium symporters (NSSs) mediate reuptake of neurotransmitters from the synaptic cleft and are targets for several therapeutics and psychostimulants. The prokaryotic NSS homologue, LeuT, represents a principal structural model for Na(+)-coupled transport catalyzed by these proteins. Here, we used site-directed fluorescence quenching spectroscopy to identify in LeuT a substrate-induced conformational rearrangement at the inner gate conceivably leading to formation of a structural intermediate preceding transition to the inward-open conformation. The substrate-induced, Na(+)-dependent change required an intact primary substrate-binding site and involved increased water exposure of the cytoplasmic end of transmembrane segment 5. The findings were supported by simulations predicting disruption of an intracellular interaction network leading to a discrete rotation of transmembrane segment 5 and the adjacent intracellular loop 2. The magnitude of the spectroscopic response correlated inversely with the transport rate for different substrates, suggesting that stability of the intermediate represents an unrecognized rate-limiting barrier in the NSS transport mechanism.

  2. Natural polyphenols: Influence on membrane transporters

    PubMed Central

    Hussain, Saad Abdulrahman; Sulaiman, Amal Ajaweed; Alhaddad, Hasan; Alhadidi, Qasim

    2016-01-01

    Accumulated evidence has focused on the use of natural polyphenolic compounds as nutraceuticals since they showed a wide range of bioactivities and exhibited protection against variety of age-related disorders. Polyphenols have variable potencies to interact, and hence alter the activities of various transporter proteins, many of them classified as anion transporting polypeptide-binding cassette transporters like multidrug resistance protein and p-glycoprotein. Some of the efflux transporters are, generally, linked with anticancer and antiviral drug resistance; in this context, polyphenols may be beneficial in modulating drug resistance by increasing the efficacy of anticancer and antiviral drugs. In addition, these effects were implicated to explain the influence of dietary polyphenols on drug efficacy as result of food-drug interactions. However, limited data are available about the influence of these components on uptake transporters. Therefore, the objective of this article is to review the potential efficacies of polyphenols in modulating the functional integrity of uptake transporter proteins, including those terminated the effect of neurotransmitters, and their possible influence in neuropharmacology. PMID:27069731

  3. Re-examining how complexin inhibits neurotransmitter release

    PubMed Central

    Trimbuch, Thorsten; Xu, Junjie; Flaherty, David; Tomchick, Diana R; Rizo, Josep; Rosenmund, Christian

    2014-01-01

    Complexins play activating and inhibitory functions in neurotransmitter release. The complexin accessory helix inhibits release and was proposed to insert into SNARE complexes to prevent their full assembly. This model was supported by ‘superclamp’ and ‘poor-clamp’ mutations that enhanced or decreased the complexin-I inhibitory activity in cell–cell fusion assays, and by the crystal structure of a superclamp mutant bound to a synaptobrevin-truncated SNARE complex. NMR studies now show that the complexin-I accessory helix does not insert into synaptobrevin-truncated SNARE complexes in solution, and electrophysiological data reveal that superclamp mutants have slightly stimulatory or no effects on neurotransmitter release, whereas a poor-clamp mutant inhibits release. Importantly, increasing or decreasing the negative charge of the complexin-I accessory helix inhibits or stimulates release, respectively. These results suggest a new model whereby the complexin accessory helix inhibits release through electrostatic (and perhaps steric) repulsion enabled by its location between the vesicle and plasma membranes. DOI: http://dx.doi.org/10.7554/eLife.02391.001 PMID:24842998

  4. Detection and Monitoring of Neurotransmitters - a Spectroscopic Analysis

    NASA Astrophysics Data System (ADS)

    Manciu, Felicia; Lee, Kendall; Durrer, William; Bennet, Kevin

    2012-10-01

    In this work we demonstrate the capability of confocal Raman mapping spectroscopy for simultaneously and locally detecting important compounds in neuroscience such as dopamine, serotonin, and adenosine. The Raman results show shifting of the characteristic vibrations of the compounds, observations consistent with previous spectroscopic studies. Although some vibrations are common in these neurotransmitters, Raman mapping was achieved by detecting non-overlapping characteristic spectral signatures of the compounds, as follows: for dopamine the vibration attributed to C-O stretching, for serotonin the indole ring stretching vibration, and for adenosine the adenine ring vibrations. Without damage, dyeing, or preferential sample preparation, confocal Raman mapping provided positive detection of each neurotransmitter, allowing association of the high-resolution spectra with specific micro-scale image regions. Such information is particularly important for complex, heterogeneous samples, where modification of the chemical or physical composition can influence the neurotransmission processes. We also report an estimated dopamine diffusion coefficient two orders of magnitude smaller than that calculated by the flow-injection method.

  5. [Mechanisms of neurotransmitter release facilitation in strontium solutions].

    PubMed

    Mukhamed'iarov, M A; Kochunova, Iu O; Telina, E N; Zefirov, A L

    2008-02-01

    Mechanisms of neurotransmitter release facilitation were studied using electrophysiological recording of end-plate currents (EPC) and nerve ending (NE) responses after substitution of extracellular Ca ions with Sr ions at the frog neuromuscular junction. The solutions with 0.5 mM concentration of Ca ions (calcium solution) or 1 mM concentration of Sr ions (strontium solution) were used where baseline neurotransmitter release (at low-frequency stimulation) is equal. Decay of paired-pulse facilitation of EPC at calcium solutions with increase of interpulse interval from 5 to 500 ms was well described by three-exponential function consisting of early, first and second components. Facilitation at strontium solutions was significantly diminished due mainly to decrease of early and first components. At the same time, EPC facilitation with rhythmic stimulation (10 or 50 imp/s) at strontium solutions was significantly increased. Also more pronounced decrease of NE response 3rd phase, reflecting potassium currents was detected under rhythmic stimulation of 50 imp/s at strontium solutions comparing to calcium solutions. It was concluded that facilitation sites underlying first and early components had lower affinity to Sr ions than to Ca ions. The enhancement of frequency facilitation at strontium solutions is mediated by two mechanisms: more pronounced broadening of NE action potential and increase of bivalent cation influx due to feebly marked activation of Ca(2+)-dependent potassium current by Sr ions, and slower dynamics of Sr(2+) removal from NE axoplasm comparing to Ca(2+).

  6. A 10(9) neutrons/pulse transportable pulsed D-D neutron source based on flexible head plasma focus unit.

    PubMed

    Niranjan, Ram; Rout, R K; Srivastava, R; Kaushik, T C; Gupta, Satish C

    2016-03-01

    A 17 kJ transportable plasma focus (PF) device with flexible transmission lines is developed and is characterized. Six custom made capacitors are used for the capacitor bank (CB). The common high voltage plate of the CB is fixed to a centrally triggered spark gap switch. The output of the switch is coupled to the PF head through forty-eight 5 m long RG213 cables. The CB has a quarter time-period of 4 μs and an estimated current of 506 kA is delivered to the PF device at 17 kJ (60 μF, 24 kV) energy. The average neutron yield measured using silver activation detector in the radial direction is (7.1 ± 1.4) × 10(8) neutrons/shot over 4π sr at 5 mbar optimum D2 pressure. The average neutron yield is more in the axial direction with an anisotropy factor of 1.33 ± 0.18. The average neutron energies estimated in the axial as well as in the radial directions are (2.90 ± 0.20) MeV and (2.58 ± 0.20) MeV, respectively. The flexibility of the PF head makes it useful for many applications where the source orientation and the location are important factors. The influence of electromagnetic interferences from the CB as well as from the spark gap on applications area can be avoided by putting a suitable barrier between the bank and the PF head.

  7. Pituitary adenylate cyclase-activating polypeptide is a sympathoadrenal neurotransmitter involved in catecholamine regulation and glucohomeostasis.

    PubMed

    Hamelink, Carol; Tjurmina, Olga; Damadzic, Ruslan; Young, W Scott; Weihe, Eberhard; Lee, Hyeon-Woo; Eiden, Lee E

    2002-01-08

    The adrenal gland is important for homeostatic responses to metabolic stress: hypoglycemia stimulates the splanchnic nerve, epinephrine is released from adrenomedullary chromaffin cells, and compensatory glucogenesis ensues. Acetylcholine is the primary neurotransmitter mediating catecholamine secretion from the adrenal medulla. Accumulating evidence suggests that a secretin-related neuropeptide also may function as a transmitter at the adrenomedullary synapse. Costaining with highly specific antibodies against the secretin-related neuropeptide pituitary adenylate cyclase-activating peptide (PACAP) and the vesicular acetylcholine transporter (VAChT) revealed that PACAP is found in nerve terminals at all mouse adrenomedullary cholinergic synapses. Mice with a targeted deletion of the PACAP gene had otherwise normal cholinergic innervation and morphology of the adrenal medulla, normal adrenal catecholamine and blood glucose levels, and an intact initial catecholamine secretory response to insulin-induced hypoglycemia. However, insulin-induced hypoglycemia was more profound and longer-lasting in PACAP knock-outs, and was associated with a dose-related lethality absent in wild-type mice. Failure of PACAP-deficient mice to adequately counterregulate plasma glucose levels could be accounted for by impaired long-term secretion of epinephrine, secondary to a lack of induction of tyrosine hydroxylase, normally occurring after insulin hypoglycemia in wild-type mice, and a consequent depletion of adrenomedullary epinephrine stores. Thus, PACAP is needed to couple epinephrine biosynthesis to secretion during metabolic stress. PACAP appears to function as an "emergency response" cotransmitter in the sympathoadrenal axis, where the primary secretory response is controlled by a classical neurotransmitter but sustained under paraphysiological conditions by a neuropeptide.

  8. [Glutamatergic neurotransmitter system in regulation of the gastrointestinal tract motor activity].

    PubMed

    Alekseeva, E V; Popova, T S; Sal'nikov, P S

    2015-01-01

    The review include actual facts, demonstrating high probability of glutamatergic neurotransmitter system role in the regulation of the gastrointestinal tract motor activity. These facts suggest significant role of the glutamatergic neurotransmitter system dysfunction in forming motor activity disorders of the digestive tract, including in patients in critical condition. The analysis is based on results of multiple experimental and clinical researches of glutamic acid and other components of the glutamatergic neurotransmitter system in central nervous system and autonomic nervous system (with the accent on the enteral nervous system) in normal conditions and with functioning changes of the glutamatergic neurotransmitter system in case of inflammation, hupoxia, stress and in critical condition.

  9. Wireless Power Transfer for Autonomous Wearable Neurotransmitter Sensors

    PubMed Central

    Nguyen, Cuong M.; Kota, Pavan Kumar; Nguyen, Minh Q.; Dubey, Souvik; Rao, Smitha; Mays, Jeffrey; Chiao, J.-C.

    2015-01-01

    In this paper, we report a power management system for autonomous and real-time monitoring of the neurotransmitter L-glutamate (L-Glu). A low-power, low-noise, and high-gain recording module was designed to acquire signal from an implantable flexible L-Glu sensor fabricated by micro-electro-mechanical system (MEMS)-based processes. The wearable recording module was wirelessly powered through inductive coupling transmitter antennas. Lateral and angular misalignments of the receiver antennas were resolved by using a multi-transmitter antenna configuration. The effective coverage, over which the recording module functioned properly, was improved with the use of in-phase transmitter antennas. Experimental results showed that the recording system was capable of operating continuously at distances of 4 cm, 7 cm and 10 cm. The wireless power management system reduced the weight of the recording module, eliminated human intervention and enabled animal experimentation for extended durations. PMID:26404311

  10. Mimicking subsecond neurotransmitter dynamics with femtosecond laser stimulated nanosystems

    NASA Astrophysics Data System (ADS)

    Nakano, Takashi; Chin, Catherine; Myint, David Mo Aung; Tan, Eng Wui; Hale, Peter John; Krishna M., Bala Murali; Reynolds, John N. J.; Wickens, Jeff; Dani, Keshav M.

    2014-06-01

    Existing nanoscale chemical delivery systems target diseased cells over long, sustained periods of time, typically through one-time, destructive triggering. Future directions lie in the development of fast and robust techniques capable of reproducing the pulsatile chemical activity of living organisms, thereby allowing us to mimic biofunctionality. Here, we demonstrate that by applying programmed femtosecond laser pulses to robust, nanoscale liposome structures containing dopamine, we achieve sub-second, controlled release of dopamine - a key neurotransmitter of the central nervous system - thereby replicating its release profile in the brain. The fast delivery system provides a powerful new interface with neural circuits, and to the larger range of biological functions that operate on this short timescale.

  11. Attenuation of forgetting by pharmacological stimulation of aminergic neurotransmitter systems.

    PubMed

    Quartermain, D; Judge, M E; Leo, P

    1988-05-01

    Mice were trained in one-way active avoidance to a criterion of 3/4 avoidances and tested under extinction conditions one week later when substantial forgetting had occurred. Thirty min prior to testing animals were injected with either saline or different doses of drugs which activate the noradrenergic (phenylephrine, salbutamol, clonidine) dopaminergic (L-dopa(Sinemet) transdihydrolisuride, apomorphine) and serotonergic (fluoxetine, 5-methoxy DMT) neurotransmitter systems. Results showed that all agents alleviated forgetting in a dose dependent fashion. Untrained mice treated with the most effective dose of representative drugs from each class did not exhibit avoidance behavior at testing indicating that the improved performance of trained animals was probably not the result of increased activity or other non-memorial effects of the drugs. It was concluded that pharmacological agents which stimulate monoamine systems may improve memory retrieval by activating a non-specific neural system which controls arousal, attention and motor readiness.

  12. Terahertz identification and quantification of neurotransmitter and neurotrophy mixture

    PubMed Central

    Peng, Yan; Yuan, Xiaorong; Zou, Xiang; Chen, Wanqing; Huang, Hui; Zhao, Hongwei; Song, Bo; Chen, Liang; Zhu, Yiming

    2016-01-01

    Terahertz spectroscopy has been widely used for investigating the fingerprint spectrum of different substances. For cancerous tissues, the greatest difficulty is the absorption peaks of various substances contained in tissues overlap with each other, which are hard to identify and quantitative analyze. As a result, it is very hard to measure the presence of cancer cell and then to diagnose accurately. In this paper, we select three typical neurotransmitters (γ-aminobutyric acid, L-glutamic acid, dopamine hydrochloride) and two typical metabolites (inositol and creatine) in neurons to measure their terahertz spectra with different mixture ratios. By choosing characteristic absorption peaks, removing baseline and using the least square method, we can identify the components and proportions of each mixture, where the goodness of fit to practical situation is up to 94%. These results provide important evidences for identifying nerve substances and obtaining exact quantitative analysis. PMID:27895988

  13. Teaching medical students basic neurotransmitter pharmacology using primary research resources.

    PubMed

    Halliday, Amy C; Devonshire, Ian M; Greenfield, Susan A; Dommett, Eleanor J

    2010-12-01

    Teaching pharmacology to medical students has long been seen as a challenge, and one to which a number of innovative approaches have been taken. In this article, we describe and evaluate the use of primary research articles in teaching second-year medical students both in terms of the information learned and the use of the papers themselves. We designed a seminar where small groups of students worked on different neurotransmitters before contributing information to a plenary session. Student feedback suggested that when the information was largely novel, students learned considerably more. Crucially, this improvement in knowledge was seen even when they had not directly studied a particular transmitter in their work groups, suggesting a shared learning experience. Moreover, the majority of students reported that using primary research papers was easy and useful, with over half stating that they would use them in future study.

  14. Orquestic regulation of neurotransmitters on reward-seeking behavior

    PubMed Central

    2014-01-01

    The ventral tegmental area is strongly associated with the reward system. Dopamine is released in areas such as the nucleus accumbens and prefrontal cortex as a result of rewarding experiences such as food, sex, and neutral stimuli that become associated with them. Electrical stimulation of the ventral tegmental area or its output pathways can itself serve as a potent reward. Different drugs that increase dopamine levels are intrinsically rewarding. Although the dopaminergic system represent the cornerstone of the reward system, other neurotransmitters such as endogenous opioids, glutamate, γ-Aminobutyric acid, acetylcholine, serotonin, adenosine, endocannabinoids, orexins, galanin and histamine all affect this mesolimbic dopaminergic system. Consequently, genetic variations of neurotransmission are thought influence reward processing that in turn may affect distinctive social behavior and susceptibility to addiction. Here, we discuss current evidence on the orquestic regulation of different neurotranmitters on reward-seeking behavior and its potential effect on drug addiction. PMID:25061480

  15. Wireless Power Transfer for Autonomous Wearable Neurotransmitter Sensors.

    PubMed

    Nguyen, Cuong M; Kota, Pavan Kumar; Nguyen, Minh Q; Dubey, Souvik; Rao, Smitha; Mays, Jeffrey; Chiao, J-C

    2015-09-23

    In this paper, we report a power management system for autonomous and real-time monitoring of the neurotransmitter L-glutamate (L-Glu). A low-power, low-noise, and high-gain recording module was designed to acquire signal from an implantable flexible L-Glu sensor fabricated by micro-electro-mechanical system (MEMS)-based processes. The wearable recording module was wirelessly powered through inductive coupling transmitter antennas. Lateral and angular misalignments of the receiver antennas were resolved by using a multi-transmitter antenna configuration. The effective coverage, over which the recording module functioned properly, was improved with the use of in-phase transmitter antennas. Experimental results showed that the recording system was capable of operating continuously at distances of 4 cm, 7 cm and 10 cm. The wireless power management system reduced the weight of the recording module, eliminated human intervention and enabled animal experimentation for extended durations.

  16. Macrocyclic Gd(3+) complexes with pendant crown ethers designed for binding zwitterionic neurotransmitters.

    PubMed

    Oukhatar, Fatima; Meudal, Hervé; Landon, Céline; Logothetis, Nikos K; Platas-Iglesias, Carlos; Angelovski, Goran; Tóth, Éva

    2015-07-27

    A series of Gd(3+) complexes exhibiting a relaxometric response to zwitterionic amino acid neurotransmitters was synthesized. The design concept involves ditopic interactions 1) between a positively charged and coordinatively unsaturated Gd(3+) chelate and the carboxylate group of the neurotransmitters and 2) between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. The chelates differ in the nature and length of the linker connecting the cyclen-type macrocycle that binds the Ln(3+) ion and the crown ether. The complexes are monohydrated, but they exhibit high proton relaxivities (up to 7.7 mM(-1)  s(-1) at 60 MHz, 310 K) due to slow molecular tumbling. The formation of ternary complexes with neurotransmitters was monitored by (1) H relaxometric titrations of the Gd(3+) complexes and by luminescence measurements on the Eu(3+) and Tb(3+) analogues at pH 7.4. The remarkable relaxivity decrease (≈80 %) observed on neurotransmitter binding is related to the decrease in the hydration number, as evidenced by luminescence lifetime measurements on the Eu(3+) complexes. These complexes show affinity for amino acid neurotransmitters in the millimolar range, which can be suited to imaging concentrations of synaptically released neurotransmitters. They display good selectivity over non-amino acid neurotransmitters (acetylcholine, serotonin, and noradrenaline) and hydrogenphosphate, but selectivity over hydrogencarbonate was not achieved.

  17. RECENT DEVELOPMENTS IN ELECTROCHEMICAL SENSORS FOR THE DETECTION OF NEUROTRANSMITTERS FOR APPLICATIONS IN BIOMEDICINE.

    PubMed

    Özel, Rıfat Emrah; Hayat, Akhtar; Andreescu, Silvana

    2015-05-03

    Neurotransmitters are important biological molecules that are essential to many neurophysiological processes including memory, cognition, and behavioral states. The development of analytical methodologies to accurately detect neurotransmitters is of great importance in neurological and biological research. Specifically designed microelectrodes or microbiosensors have demonstrated potential for rapid, real-time measurements with high spatial resolution. Such devices can facilitate study of the role and mechanism of action of neurotransmitters and can find potential uses in biomedicine. This paper reviews the current status and recent advances in the development and application of electrochemical sensors for the detection of small-molecule neurotransmitters. Measurement challenges and opportunities of electroanalytical methods to advance study and understanding of neurotransmitters in various biological models and disease conditions are discussed.

  18. RECENT DEVELOPMENTS IN ELECTROCHEMICAL SENSORS FOR THE DETECTION OF NEUROTRANSMITTERS FOR APPLICATIONS IN BIOMEDICINE

    PubMed Central

    Özel, Rıfat Emrah; Hayat, Akhtar; Andreescu, Silvana

    2015-01-01

    Neurotransmitters are important biological molecules that are essential to many neurophysiological processes including memory, cognition, and behavioral states. The development of analytical methodologies to accurately detect neurotransmitters is of great importance in neurological and biological research. Specifically designed microelectrodes or microbiosensors have demonstrated potential for rapid, real-time measurements with high spatial resolution. Such devices can facilitate study of the role and mechanism of action of neurotransmitters and can find potential uses in biomedicine. This paper reviews the current status and recent advances in the development and application of electrochemical sensors for the detection of small-molecule neurotransmitters. Measurement challenges and opportunities of electroanalytical methods to advance study and understanding of neurotransmitters in various biological models and disease conditions are discussed. PMID:26973348

  19. Mechanism of the association between Na+ binding and conformations at the intracellular gate in neurotransmitter:sodium symporters

    DOE PAGES

    Stolzenberg, Sebastian; Quick, Matthias; Zhao, Chunfeng; ...

    2015-04-13

    Neurotransmitter:sodium symporters (NSSs) terminate neurotransmission by Na+-dependent reuptake of released neurotransmitters. Previous studies suggested that Na+-binding reconfigures dynamically coupled structural elements in an allosteric interaction network (AIN) responsible for function-related conformational changes, but the intramolecular pathway of this mechanism has remained uncharted. Here we describe a new approach for the modeling and analysis of intramolecular dynamics in the bacterial NSS homolog LeuT. From microsecond-scale molecular dynamics simulations and cognate experimental verifications in both LeuT and human dopamine transporter (hDAT), we apply the novel method to identify the composition and the dynamic properties of their conserved AIN. In LeuT, two differentmore » perturbations disrupting Na+ binding and transport (i.e. replacing Na+ with Li+ or the Y268A mutation at the intracellular gate) affect the AIN in strikingly similar ways. In contrast, other mutations that affect the intracellular gate (i.e. R5A and D369A) do not significantly impair Na+ cooperativity and transport. Our analysis shows these perturbations to have much lesser effects on the AIN, underscoring the sensitivity of this novel method to the mechanistic nature of the perturbation. Notably, this set of observations holds as well for hDAT, where the aligned Y335A, R60A, and D436A mutations also produce different impacts on Na+ dependence. Furthermore, the detailed AIN generated from our method is shown to connect Na+ binding with global conformational changes that are critical for the transport mechanism. Lastly, that the AIN between the Na+ binding sites and the intracellular gate in bacterial LeuT resembles that in eukaryotic hDAT highlights the conservation of allosteric pathways underlying NSS function.« less

  20. Mechanism of the Association between Na+ Binding and Conformations at the Intracellular Gate in Neurotransmitter:Sodium Symporters.

    PubMed

    Stolzenberg, Sebastian; Quick, Matthias; Zhao, Chunfeng; Gotfryd, Kamil; Khelashvili, George; Gether, Ulrik; Loland, Claus J; Javitch, Jonathan A; Noskov, Sergei; Weinstein, Harel; Shi, Lei

    2015-05-29

    Neurotransmitter:sodium symporters (NSSs) terminate neurotransmission by Na(+)-dependent reuptake of released neurotransmitters. Previous studies suggested that Na(+)-binding reconfigures dynamically coupled structural elements in an allosteric interaction network (AIN) responsible for function-related conformational changes, but the intramolecular pathway of this mechanism has remained uncharted. We describe a new approach for the modeling and analysis of intramolecular dynamics in the bacterial NSS homolog LeuT. From microsecond-scale molecular dynamics simulations and cognate experimental verifications in both LeuT and human dopamine transporter (hDAT), we apply the novel method to identify the composition and the dynamic properties of their conserved AIN. In LeuT, two different perturbations disrupting Na(+) binding and transport (i.e. replacing Na(+) with Li(+) or the Y268A mutation at the intracellular gate) affect the AIN in strikingly similar ways. In contrast, other mutations that affect the intracellular gate (i.e. R5A and D369A) do not significantly impair Na(+) cooperativity and transport. Our analysis shows these perturbations to have much lesser effects on the AIN, underscoring the sensitivity of this novel method to the mechanistic nature of the perturbation. Notably, this set of observations holds as well for hDAT, where the aligned Y335A, R60A, and D436A mutations also produce different impacts on Na(+) dependence. Thus, the detailed AIN generated from our method is shown to connect Na(+) binding with global conformational changes that are critical for the transport mechanism. That the AIN between the Na(+) binding sites and the intracellular gate in bacterial LeuT resembles that in eukaryotic hDAT highlights the conservation of allosteric pathways underlying NSS function.

  1. [Preliminary research on multi-neurotransmitters' change regulation in 120 depression patients' brains].

    PubMed

    Chi, Ming; Qing, Xue-Mei; Pan, Yan-Shu; Xu, Feng-Quan; Liu, Chao; Zhang, Cheng; Xu, Zhen-Hua

    2014-04-01

    In view of the effective traditional Chinese medicine (TCM) in the treatment of clinical depression, the mechanism is not clear, this study attempts to research the cause of depression in a complex situation to lay the foundation for the next step of TCM curative effect evaluation. Based on the brain wave of 120 depression patients and 40 ordinary person, the change regulation of acetylcholine, dopamine, norepinephrine, depression neurotransmitters and excited neurotransmitters in the whole and various encephalic regions' multi-neurotransmitters of depression patients-serotonin are analysed by search of encephalo-telex (SET) system, which lays the foundation for the diagnosis of depression. The result showed that: contrased with the normal person group, the mean value of the six neurotransmitters in depression patients group are: (1) in the whole encephalic region of depression patients group the dopamine fall (P < 0.05), and in the double centralregions, right temporal region and right parietal region distinct fall (P < 0.01); (2) in the right temporal region of depression patients group the serotonin rise (P < 0.05); (3) in the right central region, left parietal region of depression patients group the acetylcholine fall (P < 0.05), left rear temporal region fall obviously (P < 0.01). The correlation research between antagonizing pairs of neurotransmitters and neurotransmitters: (1) the three antagonizing pairs of neurotransmitters-serotonin and dopamine, acetylcholine and norepinephrine, depression neurotransmitters and excited neurotransmitters, in ordinary person group and depression patients group are characterizeed by middle or strong negative correlation. Serotonin and dopamine, which are characterized by weak negative correlation in the right rear temporal region of ordinary person group, are characterized by strong negative correlation in the other encephalic regions and the whole encephalic (ordinary person group except the right rear temporal region

  2. Single molecule imaging of conformational dynamics in sodium-coupled transporters

    NASA Astrophysics Data System (ADS)

    Terry, Daniel S.

    Neurotransmitter:sodium symporter (NSS) proteins remove neurotransmitters released into the synapse through a transport process driven by the physiological sodium ion (Na+) gradient. NSSs for dopamine, noradrenaline, and serotonin are targeted by the psychostimulants cocaine and amphetamines, as well as by antidepressants. The crystal structure of LeuT, a prokaryotic NSS homologue, revealed the NSS molecular architecture and has been the basis for extensive structural, biochemical, and computational investigations of the mechanism of transporter proteins with a LeuT-like fold. In this dissertation, the conformational states sampled by LeuT are explored using single-molecule fluorescence resonance energy transfer imaging methods, with special focus on the motions of transmembrane helix 1a that lead to inward release of substrate. We also explored how dynamics are modulated by substrate, Na+, and protons to produce efficient transport. These advances represent a first of a kind study of the dynamics of an integral membrane protein at a truly single-molecule scale. Advances in instrumentation, analysis tools, and organic fluorophores were all required to achieve these goals, and such advances are also described. While these experiments were performed with detergent-solubilized protein, preliminary work suggests that imaging of LeuT in proteoliposomes is feasible and a fluorescence sensor assay could be used to simultaneously detect conformational dynamics and transport function.

  3. Inhibitory and excitatory amino acid neurotransmitters are utilized by the projection from the dorsal deep mesencephalic nucleus to the sublaterodorsal nucleus REM sleep induction zone

    PubMed Central

    Liang, Chang-Lin; Nguyen, Tin Quang; Marks, Gerald A.

    2014-01-01

    The sublaterodorsal nucleus (SLD) in the pons of the rat is a locus supporting short-latency induction of a REM sleep-like state following local application of a GABAA receptor antagonist or kainate, glutamate receptor agonist. One putatively relevant source of these neurotransmitters is from the region of the deep mesencephalic nucleus (DpMe) just ventrolateral to the periaquiductal gray, termed the dorsal DpMe (dDpMe). Here, the amino acid neurotransmitter innervation of SLD from dDpMe was studied utilizing anterograde tract-tracing with biotinylated dextranamine (BDA) and fluorescence immunohistochemistry visualized with laser scanning confocal microscopy. Both markers for inhibitory and excitatory amino acid neurotransmitters were found in varicose axon fibers in SLD originating from dDpMe. Vesicular glutamate transporter2 (VGLUT2) represented the largest number of anterogradely labeled varicosities followed by vesicular GABA transporter (VGAT). Numerous VGAT and VGLUT2 labeled varicosities were observed apposed to dDpMe-labeled axon fibers indicating both excitatory and inhibitory presynaptic, local modulation within the SLD. Some double-labeled BDA/VGAT varicosities were seen apposed to small somata labeled for glutamate consistent with being presynaptic to the phenotype of REM sleep-active SLD neurons. Results found support the current theoretical framework of the interaction of dDpMe and SLD in control of REM sleep, while also indicating operation of mechanisms with a greater level of complexity. PMID:24751569

  4. Single Molecule Imaging of Conformational Dynamics in Sodium-Coupled Transporters

    ERIC Educational Resources Information Center

    Terry, Daniel S.

    2013-01-01

    Neurotransmitter:sodium symporter (NSS) proteins remove neurotransmitters released into the synapse through a transport process driven by the physiological sodium ion (Na[superscript +]) gradient. NSSs for dopamine, noradrenaline, and serotonin are targeted by the psychostimulants cocaine and amphetamines, as well as by antidepressants. The…

  5. What is an antidepressant binding site doing in a bacterial transporter?

    PubMed

    Rudnick, Gary

    2007-09-21

    LeuT is a bacterial amino acid transporter belonging to a large family of membrane proteins, including the neurotransmitter transporters that are targets for antidepressant drugs. The high-resolution structure of LeuT has provided an important model for understanding structure and function in this family. Two recent papers found that LeuT can bind tricyclic antidepressants, raising the possibility that it may also serve as a model for the pharmacological properties of neurotransmitter transporters.

  6. REM Sleep at its Core – Circuits, Neurotransmitters, and Pathophysiology

    PubMed Central

    Fraigne, Jimmy J.; Torontali, Zoltan A.; Snow, Matthew B.; Peever, John H.

    2015-01-01

    Rapid eye movement (REM) sleep is generated and maintained by the interaction of a variety of neurotransmitter systems in the brainstem, forebrain, and hypothalamus. Within these circuits lies a core region that is active during REM sleep, known as the subcoeruleus nucleus (SubC) or sublaterodorsal nucleus. It is hypothesized that glutamatergic SubC neurons regulate REM sleep and its defining features such as muscle paralysis and cortical activation. REM sleep paralysis is initiated when glutamatergic SubC cells activate neurons in the ventral medial medulla, which causes release of GABA and glycine onto skeletal motoneurons. REM sleep timing is controlled by activity of GABAergic neurons in the ventrolateral periaqueductal gray and dorsal paragigantocellular reticular nucleus as well as melanin-concentrating hormone neurons in the hypothalamus and cholinergic cells in the laterodorsal and pedunculo-pontine tegmentum in the brainstem. Determining how these circuits interact with the SubC is important because breakdown in their communication is hypothesized to underlie narcolepsy/cataplexy and REM sleep behavior disorder (RBD). This review synthesizes our current understanding of mechanisms generating healthy REM sleep and how dysfunction of these circuits contributes to common REM sleep disorders such as cataplexy/narcolepsy and RBD. PMID:26074874

  7. Flavonoid nutraceuticals and ionotropic receptors for the inhibitory neurotransmitter GABA.

    PubMed

    Johnston, Graham A R

    2015-10-01

    Flavonoids that are found in nutraceuticals have many and varied effects on the activation of ionotropic receptors for GABA, the major inhibitory neurotransmitter in our brains. They can act as positive or negative modulators enhancing or reducing the effect of GABA. They can act as allosteric agonists. They can act to modulate the action of other modulators. There is considerable evidence that these flavonoids are able to enter the brain to influence brain function. They may have a range of effects including relief of anxiety, improvement in cognition, acting as neuroprotectants and as sedatives. All of these effects are sought after in nutraceuticals. A number of studies have likened flavonoids to the widely prescribed benzodiazepines as 'a new family of benzodiazepine receptor ligands'. They are much more than that with many flavonoid actions on ionotropic GABA receptors being insensitive to the classic benzodiazepine antagonist flumazenil and thus independent of the classic benzodiazepine actions. It is time to consider flavonoids in their own right as important modulators of these vital receptors in brain function. Flavonoids are rarely consumed as a single flavonoid except as dietary supplements. The effects of mixtures of flavonoids and other modulators on GABAA receptors need to be more thoroughly investigated.

  8. Neurotransmitter-precursor-supplement intervention for detoxified heroin addicts.

    PubMed

    Chen, Dingyan; Liu, Yan; He, Wulong; Wang, Hongxing; Wang, Zengzhen

    2012-06-01

    This study examined the effects of combined administration of tyrosine, lecithin, L-glutamine and L-5-hydroxytryptophan (5-HTP) on heroin withdrawal syndromes and mental symptoms in detoxified heroin addicts. In the cluster-randomized placebo-controlled trial, 83 detoxified heroin addicts were recruited from a detoxification treatment center in Wuhan, China. Patients in the intervention group (n=41) were given the combined treatment with tyrosine, lecithin, L-glutamine and 5-HTP and those in the control group (n=42) were administered the placebo. The sleep status and the withdrawal symptoms were observed daily throughout the study, and the mood states were monitored pre- and post-intervention. The results showed that the insomnia and withdrawal scores were significantly improved over time in participants in the intervention group as compared with those in the control group. A greater reduction in tension-anxiety, depression-dejection, anger-hostility, fatigue-inertia and total mood disturbance, and a greater increase in their vigor-activity symptoms were found at day 6 in the intervention group than in the control group (all P<0.05). It was concluded that the neurotransmitter-precursor-supplement intervention is effective in alleviating the withdrawal and mood symptoms and it may become a supplementary method for patients' recovery from heroin addiction.

  9. Calcitonin gene related peptide as inhibitory neurotransmitter in the ureter.

    PubMed

    Maggi, C A; Giuliani, S; Meini, S; Santicioli, P

    1995-07-01

    A dense plexus of calcitonin gene related peptide (CGRP) containing nerve fibres is present in the mammalian ureter, from which CGRP is released by depolarizing stimuli, including chemical normally present in the urine. CGRP exerts a profound, receptor-mediated, inhibitory effect on the evoked motility of the ureter by suppressing latent pacemakers in the smooth muscle. This effect is largely glibenclamide sensitive, indicating the activation of potassium (K) channels in its genesis. Electrical stimulation of intramural nerves in the guinea-pig ureter produces a transient membrane hyperpolarization, which is blocked by glibenclamide or by capsaicin pretreatment, enhanced in a low-K medium, and inhibited by a CGRP receptor antagonist. Thus endogenous CGRP acts as a neurotransmitter K channel opener in the ureter. The refractory period of the guinea-pig ureter is markedly and similarly reduced by capsaicin pretreatment or administration of a CGRP receptor antagonist, indicating that endogenous CGRP can modulate the maximal frequency of ureteral peristalsis. Using a three-chamber organ bath that enabled the separate perfusion of the renal, middle, and bladder regions of the organ, evidence was obtained that CGRP blocks propagation of impulses along the ureter through a glibenclamide-sensitive mechanism. These findings indicate a role of CGRP in the local regulation of ureteral motility and peristalsis.

  10. The neurotransmitter dopamine modulates vascular permeability in the endothelium

    PubMed Central

    Bhattacharya, Resham; Sinha, Sutapa; Yang, Su-Ping; Patra, Chittaranjan; Dutta, Shamit; Wang, Enfeng; Mukhopadhyay, Debabrata

    2008-01-01

    Background Vascular permeability factor/Vascular endothelial growth factor (VPF/VEGF), a multifunctional cytokine, is a potent inducer of vascular permeability, an important early step in angiogenesis. It is known that the neurotransmitter dopamine can inhibit VPF/VEGF mediated angiogenesis, in particular microvascular permeability, but the effectors of this action remain unclear. Results Here, we define the signaling pathway modulated by dopamine that inhibits VPF/VEGF induced vascular permeability in endothelial cells. Signals from VPF/VEGF lead to changes in the phosphorylation of tight junction protein zonula occludens (ZO-1) and adherens junction proteins like VE-cadherin and associated catenins, thus weakening endothelial cell-cell adhesion and increasing vascular permeability. We found VEGF receptor-2 (VEGFR-2) to be part of a multi-protein complex involving ZO-1, VE-cadherin and β-catenin. VPF/VEGF induced phosphorylations of VE-cadherin, β-catenin and ZO-1 were inhibited by dopamine treatment. Association of occludin with ZO-1 and ZO-1 with VE-cadherin were significantly inhibited by dopamine in VEGF treated cells. Furthermore, we identified Src as an important target for dopamine-mediated inhibition of VPF/VEGF induced permeability. Conclusion Taken together, our results provide molecular insights of dopamine function in the vascular endothelium and suggest a central role of Src in regulating key molecules that control vascular permeability. PMID:18662404

  11. Polyethylenimine Carbon Nanotube Fiber Electrodes for Enhanced Detection of Neurotransmitters

    PubMed Central

    2015-01-01

    Carbon nanotube (CNT)-based microelectrodes have been investigated as alternatives to carbon-fiber microelectrodes for the detection of neurotransmitters because they are sensitive, exhibit fast electron transfer kinetics, and are more resistant to surface fouling. Wet spinning CNTs into fibers using a coagulating polymer produces a thin, uniform fiber that can be fabricated into an electrode. CNT fibers formed in poly(vinyl alcohol) (PVA) have been used as microelectrodes to detect dopamine, serotonin, and hydrogen peroxide. In this study, we characterize microelectrodes with CNT fibers made in polyethylenimine (PEI), which have much higher conductivity than PVA-CNT fibers. PEI-CNT fibers have lower overpotentials and higher sensitivities than PVA-CNT fiber microelectrodes, with a limit of detection of 5 nM for dopamine. The currents for dopamine were adsorption controlled at PEI-CNT fiber microelectrodes, independent of scan repetition frequency, and stable for over 10 h. PEI-CNT fiber microelectrodes were resistant to surface fouling by serotonin and the metabolite interferant 5-hydroxyindoleacetic acid (5-HIAA). No change in sensitivity was observed for detection of serotonin after 30 flow injection experiments or after 2 h in 5-HIAA for PEI-CNT electrodes. The antifouling properties were maintained in brain slices when serotonin was exogenously applied multiple times or after bathing the slice in 5-HIAA. Thus, PEI-CNT fiber electrodes could be useful for the in vivo monitoring of neurochemicals. PMID:25117550

  12. Delayed release of neurotransmitter from cerebellar granule cells.

    PubMed

    Atluri, P P; Regehr, W G

    1998-10-15

    At fast chemical synapses the rapid release of neurotransmitter that occurs within a few milliseconds of an action potential is followed by a more sustained elevation of release probability, known as delayed release. Here we characterize the role of calcium in delayed release and test the hypothesis that facilitation and delayed release share a common mechanism. Synapses between cerebellar granule cells and their postsynaptic targets, stellate cells and Purkinje cells, were studied in rat brain slices. Presynaptic calcium transients were measured with calcium-sensitive fluorophores, and delayed release was detected with whole-cell recordings. Calcium influx, presynaptic calcium dynamics, and the number of stimulus pulses were altered to assess their effect on delayed release and facilitation. Following single stimuli, delayed release can be separated into two components: one lasting for tens of milliseconds that is steeply calcium-dependent, the other lasting for hundreds of milliseconds that is driven by low levels of calcium with a nearly linear calcium dependence. The amplitude, calcium dependence, and magnitude of delayed release do not correspond to those of facilitation, indicating that these processes are not simple reflections of a shared mechanism. The steep calcium dependence of delayed release, combined with the large calcium transients observed in these presynaptic terminals, suggests that for physiological conditions delayed release provides a way for cells to influence their postsynaptic targets long after their own action potential activity has subsided.

  13. Fast neurotransmitter release regulated by the endocytic scaffold intersectin

    PubMed Central

    Sakaba, Takeshi; Kononenko, Natalia L.; Bacetic, Jelena; Pechstein, Arndt; Schmoranzer, Jan; Yao, Lijun; Barth, Holger; Shupliakov, Oleg; Kobler, Oliver; Aktories, Klaus; Haucke, Volker

    2013-01-01

    Sustained fast neurotransmission requires the rapid replenishment of release-ready synaptic vesicles (SVs) at presynaptic active zones. Although the machineries for exocytic fusion and for subsequent endocytic membrane retrieval have been well characterized, little is known about the mechanisms underlying the rapid recruitment of SVs to release sites. Here we show that the Down syndrome-associated endocytic scaffold protein intersectin 1 is a crucial factor for the recruitment of release-ready SVs. Genetic deletion of intersectin 1 expression or acute interference with intersectin function inhibited the replenishment of release-ready vesicles, resulting in short-term depression, without significantly affecting the rate of endocytic membrane retrieval. Acute perturbation experiments suggest that intersectin-mediated vesicle replenishment involves the association of intersectin with the fissioning enzyme dynamin and with the actin regulatory GTPase CDC42. Our data indicate a role for the endocytic scaffold intersectin in fast neurotransmitter release, which may be of prime importance for information processing in the brain. PMID:23633571

  14. Does chronic nicotine alter neurotransmitter receptors involved in Parkinson's disease

    SciTech Connect

    Reilly, M.A.; Lapin, E.P.; Lajtha, A.; Maker, H.S.

    1986-03-05

    Cigarette smokers are fewer in number among Parkinson's Disease (PD) patients than among groups of persons who do not have PD. Several hypotheses have been proposed to explain this observation. One which must be tested is the possibility that some pharmacologic agent present in cigarette smoke may interact with some central nervous system component involved in PD. To this end, they have investigated the effect of chronic nicotine administration on receptors for some of the neurotransmitters that are affected in PD. Rats were injected for six weeks with saline or nicotine 0.8 mg/kg S.C., then killed and brains removed and dissected. The binding of (/sup 3/H)-ketanserin to serotonin receptors in frontal cortex and of (/sup 3/H)-domperidone to dopamine receptors in caudate was not affected. However, the binding of (/sup 3/H)-domperidone in nucleus accumbens was altered: the K/sub d/ increased from 0.16 +/- 0.02 nM to 0.61 +/- 0.07 nM, and the B/sub max/ increased from 507 +/- 47 fmol/mg protein to 910 +/- 43 fmol/mg (p < 0.001 for both comparisons). These values are based on three ligand concentrations. Additional studies are in progress to substantiate the data. It is concluded that chronic nicotine administration may alter dopamine receptors in nucleus accumbens.

  15. Fluorescent false neurotransmitter reveals functionally silent dopamine vesicle clusters in the striatum

    PubMed Central

    Pereira, Daniela B.; Schmitz, Yvonne; Mészáros, József; Merchant, Paolomi; Hu, Gang; Li, Shu; Henke, Adam; Lizardi-Ortiz, José E.; Karpowicz, Richard J.; Morgenstern, Travis J.; Sonders, Mark S.; Kanter, Ellen; Rodriguez, Pamela C.; Mosharov, Eugene V.; Sames, Dalibor; Sulzer, David

    2016-01-01

    Neurotransmission at dopaminergic synapses has been studied with techniques that provide high temporal resolution but cannot resolve individual synapses. To elucidate the spatial dynamics and heterogeneity of individual dopamine boutons, we developed fluorescent false neurotransmitter 200 (FFN200), a vesicular monoamine transporter 2 (VMAT2) substrate that is the first probe to selectively trace monoamine exocytosis in both neuronal cell culture and brain tissue. By monitoring electrically-evoked Ca2+ transients with GCaMP3 and FFN200 release simultaneously, we find that only a small fraction of dopamine boutons that exhibit Ca2+ influx engage in exocytosis, a result confirmed with activity-dependent loading of the endocytic probe FM 1-43. Thus, only a low fraction of striatal dopamine axonal sites with uptake-competent VMAT2 vesicles are capable of transmitter release. This is consistent with the presence of functionally “silent” dopamine vesicle clusters and represents a first report suggestive of presynaptically silent neuromodulatory synapses. PMID:26900925

  16. Early Antipsychotic Treatment in Juvenile Rats Elicits Long-Term Alterations to the Dopamine Neurotransmitter System.

    PubMed

    De Santis, Michael; Lian, Jiamei; Huang, Xu-Feng; Deng, Chao

    2016-11-22

    Prescription of antipsychotic drugs (APDs) to children has substantially increased in recent years. Whilst current investigations into potential long-term effects have uncovered some alterations to adult behaviours, further investigations into potential changes to neurotransmitter systems are required. The current study investigated potential long-term changes to the adult dopamine (DA) system following aripiprazole, olanzapine and risperidone treatment in female and male juvenile rats. Levels of tyrosine hydroxylase (TH), phosphorylated-TH (p-TH), dopamine active transporter (DAT), and D₁ and D₂ receptors were measured via Western blot and/or receptor autoradiography. Aripiprazole decreased TH and D₁ receptor levels in the ventral tegmental area (VTA) and p-TH levels in the prefrontal cortex (PFC) of females, whilst TH levels decreased in the PFC of males. Olanzapine decreased PFC p-TH levels and increased D₂ receptor expression in the PFC and nucleus accumbens (NAc) in females only. Additionally, risperidone treatment increased D₁ receptor levels in the hippocampus of females, whilst, in males, p-TH levels increased in the PFC and hippocampus, D₁ receptor expression decreased in the NAc, and DAT levels decreased in the caudate putamen (CPu), and elevated in the VTA. These results suggest that early treatment with various APDs can cause different long-term alterations in the adult brain, across both treatment groups and genders.

  17. Early Antipsychotic Treatment in Juvenile Rats Elicits Long-Term Alterations to the Dopamine Neurotransmitter System

    PubMed Central

    De Santis, Michael; Lian, Jiamei; Huang, Xu-Feng; Deng, Chao

    2016-01-01

    Prescription of antipsychotic drugs (APDs) to children has substantially increased in recent years. Whilst current investigations into potential long-term effects have uncovered some alterations to adult behaviours, further investigations into potential changes to neurotransmitter systems are required. The current study investigated potential long-term changes to the adult dopamine (DA) system following aripiprazole, olanzapine and risperidone treatment in female and male juvenile rats. Levels of tyrosine hydroxylase (TH), phosphorylated-TH (p-TH), dopamine active transporter (DAT), and D1 and D2 receptors were measured via Western blot and/or receptor autoradiography. Aripiprazole decreased TH and D1 receptor levels in the ventral tegmental area (VTA) and p-TH levels in the prefrontal cortex (PFC) of females, whilst TH levels decreased in the PFC of males. Olanzapine decreased PFC p-TH levels and increased D2 receptor expression in the PFC and nucleus accumbens (NAc) in females only. Additionally, risperidone treatment increased D1 receptor levels in the hippocampus of females, whilst, in males, p-TH levels increased in the PFC and hippocampus, D1 receptor expression decreased in the NAc, and DAT levels decreased in the caudate putamen (CPu), and elevated in the VTA. These results suggest that early treatment with various APDs can cause different long-term alterations in the adult brain, across both treatment groups and genders. PMID:27879654

  18. Novel repeat polymorphisms of the dopaminergic neurotransmitter genes among dogs and wolves.

    PubMed

    Hejjas, Krisztina; Vas, Judit; Kubinyi, Eniko; Sasvari-Szekely, Maria; Miklosi, Adam; Ronai, Zsolt

    2007-12-01

    Genetic polymorphisms of the neurotransmission systems are intensively studied in the human because of a possible influence on personality traits and the risk of psychiatric disorders. The investigation of genetic variations of the dog genome has recently been a promising approach, as a considerable similarity can be observed between dogs and humans, in both genetic and social aspects, suggesting that the dog could become an appropriate animal model of human behavioral genetic studies. The aim of our study was the identification and analysis of variable number of tandem repeats polymorphisms (VNTRs) in the genes of the dopaminergic neurotransmitter system of dogs. The in silico search was followed by the development of PCR-based techniques for the analysis of the putative VNTRs. Highly variable repetitive sequence regions were found in the tyrosine hydroxylase (TH), dopamine transporter (DAT), and dopamine beta-hydroxylase (DBH) genes. Allele frequency and genotype distribution of these novel polymorphisms together with the exon 3 and exon 1 VNTR of the dopamine D4 receptor gene were determined in a large sample involving four dog breeds (German Shepherd, Belgian Tervueren, Groenandael, and Malinois) and European Grey Wolves. A significant difference of allele and genotype frequencies was demonstrated among the analyzed breeds; therefore, an association analysis was also carried out between the activity-impulsivity phenotype and the described VNTRs. Preliminary findings are presented that polymorphisms of the DRD4, DBH, and DAT genes can be associated with attention deficit among Belgian Tervuerens.

  19. Direct assessment of substrate binding to the Neurotransmitter:Sodium Symporter LeuT by solid state NMR

    PubMed Central

    Erlendsson, Simon; Gotfryd, Kamil; Larsen, Flemming Hofmann; Mortensen, Jonas Sigurd; Geiger, Michel-Andreas; van Rossum, Barth-Jan; Oschkinat, Hartmut; Gether, Ulrik; Teilum, Kaare; Loland, Claus J

    2017-01-01

    The Neurotransmitter:Sodium Symporters (NSSs) represent an important class of proteins mediating sodium-dependent uptake of neurotransmitters from the extracellular space. The substrate binding stoichiometry of the bacterial NSS protein, LeuT, and thus the principal transport mechanism, has been heavily debated. Here we used solid state NMR to specifically characterize the bound leucine ligand and probe the number of binding sites in LeuT. We were able to produce high-quality NMR spectra of substrate bound to microcrystalline LeuT samples and identify one set of sodium-dependent substrate-specific chemical shifts. Furthermore, our data show that the binding site mutants F253A and L400S, which probe the major S1 binding site and the proposed S2 binding site, respectively, retain sodium-dependent substrate binding in the S1 site similar to the wild-type protein. We conclude that under our experimental conditions there is only one detectable leucine molecule bound to LeuT. DOI: http://dx.doi.org/10.7554/eLife.19314.001 PMID:28117663

  20. Effects of low dose endosulfan exposure on brain neurotransmitter levels in the African clawed frog Xenopus laevis.

    PubMed

    Preud'homme, Valérie; Milla, Sylvain; Gillardin, Virginie; De Pauw, Edwin; Denoël, Mathieu; Kestemont, Patrick

    2015-02-01

    Understanding the impact of pesticides in amphibians is of growing concern to assess the causes of their decline. Among pesticides, endosulfan belongs to one of the potential sources of danger because of its wide use and known effects, particularly neurotoxic, on a variety of organisms. However, the effect of endosulfan was not yet evaluated on amphibians at levels encompassing simultaneously brain neurotransmitters and behavioural endpoints. In this context, tadpoles of the African clawed frog Xenopus laevis were submitted to four treatments during 27 d: one control, one ethanol control, and two low environmental concentrations of endosulfan (0.1 and 1 μg L(-1)). Endosulfan induced a significant increase of brain serotonin level at both concentrations and a significant increase of brain dopamine and GABA levels at the lower exposure but acetylcholinesterase activity was not modified by the treatment. The gene coding for the GABA transporter 1 was up-regulated in endosulfan contaminated tadpoles while the expression of other genes coding for the neurotransmitter receptors or for the enzymes involved in their metabolic pathways was not significantly modified by endosulfan exposure. Endosulfan also affected foraging, and locomotion in links with the results of the physiological assays, but no effects were seen on growth. These results show that low environmental concentrations of endosulfan can induce adverse responses in X. laevis tadpoles. At a broader perspective, this suggests that more research using and linking multiple markers should be used to understand the complex mode of action of pollutants.

  1. Direct assessment of substrate binding to the Neurotransmitter:Sodium Symporter LeuT by solid state NMR.

    PubMed

    Erlendsson, Simon; Gotfryd, Kamil; Larsen, Flemming Hofmann; Mortensen, Jonas Sigurd; Geiger, Michel-Andreas; van Rossum, Barth-Jan; Oschkinat, Hartmut; Gether, Ulrik; Teilum, Kaare; Loland, Claus J

    2017-01-24

    The Neurotransmitter:Sodium Symporters (NSSs) represent an important class of proteins mediating sodium-dependent uptake of neurotransmitters from the extracellular space. The substrate binding stoichiometry of the bacterial NSS protein, LeuT, and thus the principal transport mechanism, has been heavily debated. Here we used solid state NMR to specifically characterize the bound leucine ligand and probe the number of binding sites in LeuT. We were able to produce high-quality NMR spectra of substrate bound to microcrystalline LeuT samples and identify one set of sodium-dependent substrate-specific chemical shifts. Furthermore, our data show that the binding site mutants F253A and L400S, which probe the major S1 binding site and the proposed S2 binding site, respectively, retain sodium-dependent substrate binding in the S1 site similar to the wild-type protein. We conclude that under our experimental conditions there is only one detectable leucine molecule bound to LeuT.

  2. Coupled global and local changes direct substrate translocation by neurotransmitter-sodium symporter ortholog LeuT.

    PubMed

    Cheng, Mary Hongying; Bahar, Ivet

    2013-08-06

    Significant advances have been made in recent years in characterizing neurotransmitter:sodium symporter (NSS) family structure and function. Yet, many time-resolved events and intermediates that control the various stages of transport cycle remain to be elucidated. Whether NSSs harbor one or two sites for binding their substrates (neurotransmitters or amino acids), and what the role of the secondary site S2 is, if any, are still unresolved. Using molecular modeling and simulations for LeuT, a bacterial NSS, we present a comprehensive account of substrate-binding and -stabilization events, and subsequently triggered interactions leading to substrate (alanine) release. LeuT instantaneous conformation as it reconfigures from substrate-receiving (outward-facing) to -releasing (inward-facing) state appears to be a determinant of its affinity to bind substrate at site S2. In the outward-facing state, S1 robustly binds alanine and regulates subsequent redistribution of interactions to trigger extracellular gate closure; whereas S2 is only a transient binding site. The substrate-binding affinity at S2 increases in an intermediate close to inward-facing state. LeuT harbors the two substrate-binding sites, and small displacements of second substrate near S2 are observed to induce concerted small translocations in the substrate bound to primary site S1, although complete release requires collective structural rearrangements that fully expose the intracellular vestibule to the cytoplasm.

  3. Contributions to the field of neurotransmitters by Japanese scientists, and reflections on my own research.

    PubMed

    Otsuka, Masanori

    2007-03-01

    PART I DESCRIBES IMPORTANT CONTRIBUTIONS MADE BY SOME JAPANESE PIONEERS IN THE FIELD OF NEUROTRANSMITTERS: (their achievements in parentheses) J. Takamine (isolation and crystallization of adrenaline); K. Shimidzu (early hint for acetylcholine as a neurotransmitter); F. Kanematsu (donation of the Kanematsu Memorial Institute in Sydney); T. Hayashi (discovery of the excitatory action of glutamate and the inhibitory action of GABA); and I. Sano (discovery of a high concentration of dopamine in striatum, its reduction in a patient with Parkinson's disease and the treatment with DOPA). In Part II, I present some of my reflections on my research on neurotransmitters. The work of my colleagues and myself has made some significant contributions to the establishment of neurotransmitter roles played by GABA and substance P, the first amino acid and the first peptide neurotransmitters, respectively. By the early 1960s, 3 substances, i.e., acetylcholine, noradrenaline, and adrenaline, had been established as neurotransmitters. Now the number of neurotransmitters is believed to be as many as 50 or even more mainly due to the inclusion of several amino acids and a large number of peptide transmitters.

  4. Contributions to the field of neurotransmitters by Japanese scientists, and reflections on my own research

    PubMed Central

    Otsuka, Masanori

    2007-01-01

    Part I describes important contributions made by some Japanese pioneers in the field of neurotransmitters: (their achievements in parentheses) J. Takamine (isolation and crystallization of adrenaline); K. Shimidzu (early hint for acetylcholine as a neurotransmitter); F. Kanematsu (donation of the Kanematsu Memorial Institute in Sydney); T. Hayashi (discovery of the excitatory action of glutamate and the inhibitory action of GABA); and I. Sano (discovery of a high concentration of dopamine in striatum, its reduction in a patient with Parkinson’s disease and the treatment with DOPA). In Part II, I present some of my reflections on my research on neurotransmitters. The work of my colleagues and myself has made some significant contributions to the establishment of neurotransmitter roles played by GABA and substance P, the first amino acid and the first peptide neurotransmitters, respectively. By the early 1960s, 3 substances, i.e., acetylcholine, noradrenaline, and adrenaline, had been established as neurotransmitters. Now the number of neurotransmitters is believed to be as many as 50 or even more mainly due to the inclusion of several amino acids and a large number of peptide transmitters. PMID:24019584

  5. Hurdles with using in vitro models to predict human blood-brain barrier drug permeability: a special focus on transporters and metabolizing enzymes.

    PubMed

    Shawahna, Ramzi; Decleves, Xavier; Scherrmann, Jean-Michel

    2013-01-01

    The penetration of drugs into the human brain through the blood-brain barrier (BBB) is a major obstacle limiting the development of successful neuropharmaceuticals. This restricted permeability is due to the delicate intercellular junctions, efflux transporters and metabolizing enzymes present at the BBB. The pharmaceutical industry and academic research relies heavily on permeability studies conducted in animals and in vitro models of the BBB. This text reviews the available animal and in vitro BBB models with special emphasis on the situation in freshly isolated human brain microvessels and the unique tightness between brain endothelial cells, drug transport pathways and metabolic capacity. We first outline the delicate structure of the intercellular junctions and the particular interaction between the brain endothelial cells and other components of the neurovascular unit. We then examine the differences in transporters and metabolizing enzymes between species and in vitro systems and those found in isolated brain microvessels. Finally, we review the possibilities of benchmarking in vitro models of the BBB in terms of gene and protein expression.

  6. Phorbol Ester Effects on Neurotransmission: Interaction with Neurotransmitters and Calcium in Smooth Muscle

    NASA Astrophysics Data System (ADS)

    Baraban, Jay M.; Gould, Robert J.; Peroutka, Stephen J.; Snyder, Solomon H.

    1985-01-01

    Stimulation of the phosphatidylinositol cycle by neurotransmitters generates diacylglycerol, an activator of protein kinase C, which may regulate some forms of neurotransmission. Phorbol esters, potent inflammatory and tumorpromoting compounds, also activate protein kinase C. We demonstrate potent and selective effects of phorbol esters on smooth muscle, indicating a role for protein kinase C in neurotransmission. In rat vas deferens and dog basilar artery, phorbol esters synergize with calcium to mimic the contractile effects of neurotransmitters that act through the phosphatidylinositol cycle. In guinea pig ileum and rat uterus, phorbol esters block contractions produced by these neurotransmitters.

  7. Neurotransmitters and neuromodulators controlling the anterior byssus retractor muscle of Mytilus edulis.

    PubMed

    Muneoka, Y; Fujisawa, Y; Matsuura, M; Ikeda, T

    1991-01-01

    1. The anterior byssus retractor muscle (ABRM) of Mytilus edulis is innervated by at least two kinds of nerves, excitatory and relaxing nerves. The principal neurotransmitters released from these nerves have been shown to be acetylcholine and serotonin, respectively. 2. Some other monoamines, such as dopamine and octopamine, and various peptides, such as FMRFamide-related peptides, Mytilus inhibitory peptides, SCP-related peptides and a catch-relaxing peptide, may also be involved in the regulation of the muscle as neurotransmitters or neuromodulators. 3. The ABRM seems to be typical of invertebrate muscles controlled by multiple neurotransmitters and neuromodulators.

  8. Synaptic Assembly of the Brain in the Absence of Neurotransmitter Secretion

    NASA Astrophysics Data System (ADS)

    Verhage, Matthijs; Maia, Ascanio S.; Plomp, Jaap J.; Brussaard, Arjen B.; Heeroma, Joost H.; Vermeer, Hendrika; Toonen, Ruud F.; Hammer, Robert E.; van den Berg, Timo K.; Missler, Markus; Geuze, Hans J.; Südhof, Thomas C.

    2000-02-01

    Brain function requires precisely orchestrated connectivity between neurons. Establishment of these connections is believed to require signals secreted from outgrowing axons, followed by synapse formation between selected neurons. Deletion of a single protein, Munc18-1, in mice leads to a complete loss of neurotransmitter secretion from synaptic vesicles throughout development. However, this does not prevent normal brain assembly, including formation of layered structures, fiber pathways, and morphologically defined synapses. After assembly is completed, neurons undergo apoptosis, leading to widespread neurodegeneration. Thus, synaptic connectivity does not depend on neurotransmitter secretion, but its maintenance does. Neurotransmitter secretion probably functions to validate already established synaptic connections.

  9. Water-transporting proteins.

    PubMed

    Zeuthen, Thomas

    2010-04-01

    Transport through lipids and aquaporins is osmotic and entirely driven by the difference in osmotic pressure. Water transport in cotransporters and uniporters is different: Water can be cotransported, energized by coupling to the substrate flux by a mechanism closely associated with protein. In the K(+)/Cl(-) and the Na(+)/K(+)/2Cl(-) cotransporters, water is entirely cotransported, while water transport in glucose uniporters and Na(+)-coupled transporters of nutrients and neurotransmitters takes place by both osmosis and cotransport. The molecular mechanism behind cotransport of water is not clear. It is associated with the substrate movements in aqueous pathways within the protein; a conventional unstirred layer mechanism can be ruled out, due to high rates of diffusion in the cytoplasm. The physiological roles of the various modes of water transport are reviewed in relation to epithelial transport. Epithelial water transport is energized by the movements of ions, but how the coupling takes place is uncertain. All epithelia can transport water uphill against an osmotic gradient, which is hard to explain by simple osmosis. Furthermore, genetic removal of aquaporins has not given support to osmosis as the exclusive mode of transport. Water cotransport can explain the coupling between ion and water transport, a major fraction of transepithelial water transport and uphill water transport. Aquaporins enhance water transport by utilizing osmotic gradients and cause the osmolarity of the transportate to approach isotonicity.

  10. High harmonics focusing undulator

    SciTech Connect

    Varfolomeev, A.A.; Hairetdinov, A.H.; Smirnov, A.V.; Khlebnikov, A.S.

    1995-12-31

    It was shown in our previous work that there exist a possibility to enhance significantly the {open_quote}natural{close_quote} focusing properties of the hybrid undulator. Here we analyze the actual undulator configurations which could provide such field structure. Numerical simulations using 2D code PANDIRA were carried out and the enhanced focusing properties of the undulator were demonstrated. The obtained results provide the solution for the beam transport in a very long (short wavelength) undulator schemes.

  11. The role of serotonin and neurotransmitters during craniofacial development.

    PubMed

    Moiseiwitsch, J R

    2000-01-01

    Several neurotransmitters, in particular serotonin (5-HT), have demonstrated multiple functions during early development and mid-gestational craniofacial morphogenesis. Early studies indicated that 5-HT is present in the oocyte, where it appears to function as a regulator of cell cleavage. Later, it has a significant role during gastrulation, during which there are significant areas of 5-HT uptake in the primitive streak. Subsequently, in association with neurulation, 5-HT uptake is seen in the floor plate of the developing neural tube. During neural crest formation and branchial arch formation, 5-HT has been demonstrated to facilitate cell migration and stimulate cell differentiation. During morphogenesis of the craniofacial structures, 5-HT stimulates dental development and may aid in cusp formation. All of the most commonly prescribed antidepressant drugs inhibit serotonin uptake, yet they do not appear to cause major craniofacial malformations in vivo. Given the wide spectrum of effects that 5-HT has during development, it is difficult to understand why these anti-depressants are not major teratogens. Redundancy within the system may allow receptor and uptake pathways to function normally even with lower than normal levels of circulating serotonin. Serotonin-binding proteins, that are expressed in most craniofacial regions at critical times during craniofacial development, may have a buffering capacity that maintains adequate 5-HT tissue concentrations over a wide range of 5-HT serum concentrations. Dental development appears to be particularly sensitive to even small fluctuations in concentrations of 5-HT. Therefore, it may be that children of patients who have received selective serotonergic re-uptake inhibitors (such as Prozac and Zoloft) or the less selective tricyclic anti-depressant drugs (such as Elavil) would be at a higher risk for developmental dental defects such as anodontia and hypodontia. In this review, the evidence supporting a role for 5-HT

  12. Acute effects of tianeptine on circulating neurotransmitters and cardiovascular parameters.

    PubMed

    Lechin, Fuad; van der Dijs, Bertha; Hernández, Gerardo; Orozco, Beatriz; Rodríguez, Simon; Baez, Scarlet

    2006-03-01

    Tianeptine is a serotonin-uptake enhancer drug whose antidepressant effectiveness is based on its ability to reduce rather than increase serotonin availability at the synaptic cleft. This paradoxical neuropharmacological mechanism has raised doubt among neuropharmacologists and psychiatrists as to the role of tianeptine as a trusty-reliable antidepressant drug. This controversial issue led us to investigate the acute effects of a single, oral dose (12.5 mg) of this drug on circulating neurotransmitters and cardiovascular parameters in 50 healthy subjects. The drug provoked a striking and significant reduction of plasma noradrenaline (NA) and plasma serotonin (f-5-HT) while it increased plasma dopamine (DA) and platelet serotonin (p-5-HT) concentrations within the 4-h study period. No adrenaline (Ad) changes were registered. The NA/Ad ratio and the f-5-HT/p-5-HT ratio showed significant reduction throughout the test. Finally, although diastolic blood pressure (DBP) showed significant decrease, neither systolic blood pressure (SBP) nor heart rate (HR) showed significant change. These findings are consistent with the postulation that tianeptine reduces both neural sympathetic activity and parasympathetic activity without affecting adrenal sympathetic activity, enabling us to discuss the possible mechanisms involved in the antidepressant effects of tianeptine. The well-known fact that major depressed patients always show raised NA plus lower than normal p-5-HT levels, both disorders which are normalized by tianeptine, gives neurochemical support to the clinical improvement triggered by the drug in these patients. Summarizing, the results presented in this study demonstrate that tianeptine triggers significant reduction of circulating noradrenaline and plasma serotonin while increasing circulating dopamine and platelet serotonin. Other possible neuropharmacological effects are also discussed.

  13. Neurotransmitter-based strategies for the treatment of cognitive dysfunction in Down syndrome.

    PubMed

    Das, Devsmita; Phillips, Cristy; Hsieh, Wayne; Sumanth, Krithika; Dang, Van; Salehi, Ahmad

    2014-10-03

    Down syndrome (DS) is a multisystem disorder affecting the cardiovascular, respiratory, gastrointestinal, neurological, hematopoietic, and musculoskeletal systems and is characterized by significant cognitive disability and a possible common pathogenic mechanism with Alzheimer's disease. During the last decade, numerous studies have supported the notion that the triplication of specific genes on human chromosome 21 plays a significant role in cognitive dysfunction in DS. Here we reviewed studies in trisomic mouse models and humans, including children and adults with DS. In order to identify groups of genes that contribute to cognitive disability in DS, multiple mouse models of DS with segmental trisomy have been generated. Over-expression of these particular genes in DS can lead to dysfunction of several neurotransmitter systems. Therapeutic strategies for DS have either focused on normalizing the expression of triplicated genes with important roles in DS or restoring the function of these systems. Indeed, our extensive review of studies on the pathogenesis of DS suggests that one plausible strategy for the treatment of cognitive dysfunction is to target the cholinergic, serotonergic, GABA-ergic, glutamatergic, and norepinephrinergic system. However, a fundamental strategy for treatment of cognitive dysfunction in DS would include reducing to normal levels the expression of specific triplicated genes in affected systems before the onset of neurodegeneration.

  14. Early toxic effect of 6-hydroxydopamine on extracellular concentrations of neurotransmitters in the rat striatum: an in vivo microdialysis study.

    PubMed

    Tobón-Velasco, Julio César; Silva-Adaya, Daniela; Carmona-Aparicio, Liliana; García, Esperanza; Galván-Arzate, Sonia; Santamaría, Abel

    2010-12-01

    The early effects of 6-OHDA as a Parkinsonian model in rodents are relevant since pharmacological and toxicological points of view, as they can explain the acute and chronic deleterious events occurring in the striatum. In this study, we focused our attention on the neurochemical and motor dysfunction produced after a pulse infusion of 6-OHDA, paying special attention to the capacity of this molecule to induce neurotransmitter release and behavioural alterations. Extracellular levels of dopamine, serotonin, norepinephrine, glutamate, glutamine, aspartate, glycine and GABA were all assessed in striatal dialysates in freely moving rats immediately after exposed to a single pulse of 6-OHDA in dorsal striatum, and major behavioural markers of motor alterations were simultaneously explored. Enhanced release of dopamine, serotonin and norepinephrine was found immediately after 6-OHDA pulse. Delayed glutamate and glycine release were detected and a biphasic effect on GABA was observed. Mostly serotonin and dopamine outflow, followed by glutamate, correlated with wet dog shakes and other behavioural qualitative alterations. Early dopamine release, accompanied by other neurotransmitters, can generate an excitatory environment affecting the striatal neurons with immediate consequences for behavioural performance. In turn, these changes might be accounting for later features of toxicity described in this model.

  15. Mimicking Neurotransmitter Release in Chemical Synapses via Hysteresis Engineering in MoS2 Transistors.

    PubMed

    Arnold, Andrew J; Razavieh, Ali; Nasr, Joseph R; Schulman, Daniel S; Eichfeld, Chad M; Das, Saptarshi

    2017-03-28

    Neurotransmitter release in chemical synapses is fundamental to diverse brain functions such as motor action, learning, cognition, emotion, perception, and consciousness. Moreover, improper functioning or abnormal release of neurotransmitter is associated with numerous neurological disorders such as epilepsy, sclerosis, schizophrenia, Alzheimer's disease, and Parkinson's disease. We have utilized hysteresis engineering in a back-gated MoS2 field effect transistor (FET) in order to mimic such neurotransmitter release dynamics in chemical synapses. All three essential features, i.e., quantal, stochastic, and excitatory or inhibitory nature of neurotransmitter release, were accurately captured in our experimental demonstration. We also mimicked an important phenomenon called long-term potentiation (LTP), which forms the basis of human memory. Finally, we demonstrated how to engineer the LTP time by operating the MoS2 FET in different regimes. Our findings could provide a critical component toward the design of next-generation smart and intelligent human-like machines and human-machine interfaces.

  16. Neurotransmitter signaling pathways required for normal development in Xenopus laevis embryos: a pharmacological survey screen

    PubMed Central

    Sullivan, Kelly G.; Levin, Michael

    2016-01-01

    Neurotransmitters are not only involved in brain function but are also important signaling molecules for many diverse cell types. Neurotransmitters are widely conserved, from evolutionarily ancient organisms lacking nervous systems through man. Here, we report results from a loss- and gain-of-function survey, using pharmacologic modulators of several neurotransmitter pathways to examine possible roles in normal embryogenesis. Applying reagents targeting the glutamatergic, adrenergic, and dopaminergic pathways to embryos of Xenopus laevis from gastrulation to organogenesis stages, we observed and quantified numerous malformations including craniofacial defects, hyperpigmentation, muscle mispatterning, and miscoiling of the gut. These data implicate several key neurotransmitters in new embryonic patterning roles, reveal novel earlier stages for processes involved in eye development, suggest new targets for subsequent molecular-genetic investigation, and highlight the necessity for in-depth toxicology studies of psychoactive compounds to which human embryos might be exposed during pregnancy. PMID:27060969

  17. Ion focusing

    DOEpatents

    Cooks, Robert Graham; Baird, Zane; Peng, Wen-Ping

    2017-01-17

    The invention generally relates to apparatuses for focusing ions at or above ambient pressure and methods of use thereof. In certain embodiments, the invention provides an apparatus for focusing ions that includes an electrode having a cavity, at least one inlet within the electrode configured to operatively couple with an ionization source, such that discharge generated by the ionization source is injected into the cavity of the electrode, and an outlet. The cavity in the electrode is shaped such that upon application of voltage to the electrode, ions within the cavity are focused and directed to the outlet, which is positioned such that a proximal end of the outlet receives the focused ions and a distal end of the outlet is open to ambient pressure.

  18. Ion focusing

    SciTech Connect

    Cooks, Robert Graham; Baird, Zane; Peng, Wen-Ping

    2015-11-10

    The invention generally relates to apparatuses for focusing ions at or above ambient pressure and methods of use thereof. In certain embodiments, the invention provides an apparatus for focusing ions that includes an electrode having a cavity, at least one inlet within the electrode configured to operatively couple with an ionization source, such that discharge generated by the ionization source is injected into the cavity of the electrode, and an outlet. The cavity in the electrode is shaped such that upon application of voltage to the electrode, ions within the cavity are focused and directed to the outlet, which is positioned such that a proximal end of the outlet receives the focused ions and a distal end of the outlet is open to ambient pressure.

  19. Smart Growth and Transportation

    EPA Pesticide Factsheets

    Describes the relationship between smart growth and transportation, focusing smart and sustainable street design, transit-oriented development, parking management, sustainable transportation planning, and related resources.

  20. Amphetamine, 3,4-methylenedioxymethamphetamine, lysergic acid diethylamide, and metabolites of the catecholamine neurotransmitters are agonists of a rat trace amine receptor.

    PubMed

    Bunzow, J R; Sonders, M S; Arttamangkul, S; Harrison, L M; Zhang, G; Quigley, D I; Darland, T; Suchland, K L; Pasumamula, S; Kennedy, J L; Olson, S B; Magenis, R E; Amara, S G; Grandy, D K

    2001-12-01

    The trace amine para-tyramine is structurally and functionally related to the amphetamines and the biogenic amine neurotransmitters. It is currently thought that the biological activities elicited by trace amines such as p-tyramine and the psychostimulant amphetamines are manifestations of their ability to inhibit the clearance of extracellular transmitter and/or stimulate the efflux of transmitter from intracellular stores. Here we report the discovery and pharmacological characterization of a rat G protein-coupled receptor that stimulates the production of cAMP when exposed to the trace amines p-tyramine, beta-phenethylamine, tryptamine, and octopamine. An extensive pharmacological survey revealed that psychostimulant and hallucinogenic amphetamines, numerous ergoline derivatives, adrenergic ligands, and 3-methylated metabolites of the catecholamine neurotransmitters are also good agonists at the rat trace amine receptor 1 (rTAR1). These results suggest that the trace amines and catecholamine metabolites may serve as the endogenous ligands of a novel intercellular signaling system found widely throughout the vertebrate brain and periphery. Furthermore, the discovery that amphetamines, including 3,4-methylenedioxymethamphetamine (MDMA; "ecstasy"), are potent rTAR1 agonists suggests that the effects of these widely used drugs may be mediated in part by this receptor as well as their previously characterized targets, the neurotransmitter transporter proteins.

  1. Cryogenic fluid management (base R/T): Cryogenic fluid systems, Cryogenic Orbital Nitrogen Experiment (CONE), Cryogenic Orbital Hydrogen Experiment (COHE). (Transportation focused technology)

    NASA Technical Reports Server (NTRS)

    Symons, Pat

    1991-01-01

    The topics presented are covered in viewgraph form. The concluded remarks are: (1) advanced cryogenic fluid systems technology is enhancing or enabling to all known transportation scenarios for space exploration; (2) an integrated/coordinated program involving LeRC/MSFC has been formulated to address all known CFM needs - new needs should they develop, can be accommodated within available skills/facilities; (3) all required/experienced personnel and facilities are finally in place - data from initial ground-based experiments is being collected and analyzed - small scale STS experiments are nearing flight - program is beginning to yield significant results; (4) future proposed funding to primarily come from two sources; and (5) cryogenic fluid experimentation is essential to provide required technology and assure implementation in future NASA missions.

  2. Electrochemical sensors and biosensors for determination of catecholamine neurotransmitters: A review.

    PubMed

    Ribeiro, José A; Fernandes, Paula M V; Pereira, Carlos M; Silva, F

    2016-11-01

    This work describes the state of the art of electrochemical devices for the detection of an important class of neurotransmitters: the catecholamines. This class of biogenic amines includes dopamine, noradrenaline (also called norepinephrine) and adrenaline (also called epinephrine). Researchers have focused on the role of catecholamine molecules within the human body because they are involved in many important biological functions and are commonly associated with several diseases, such as Alzheimer's and Parkinson. Furthermore, the release of catecholamines as a consequence of induced stimulus is an important indicator of reward-related behaviors, such as food, drink, sex and drug addiction. Thus, the development of simple, fast and sensitive electroanalytical methodologies for the determination of catecholamines is currently needed in clinical and biomedical fields, as they have the potential to serve as clinically relevant biomarkers for specific disease states or to monitor treatment efficacy. Currently, three main strategies have used by researchers to detect catecholamine molecules, namely: the use electrochemical materials in combination with, for example, HPLC or FIA, the incorporation of new materials/layers on the sensor surfaces (Tables 1-7) and in vivo detection, manly by using FSCV at CFMEs (Section 10). The developed methodologies were able not only to accurately detect catecholamines at relevant concentration levels, but to do so in the presence of co-existing interferences in samples detected (ascorbate, for example). This review examines the progress made in electrochemical sensors for the selective detection of catecholamines in the last 15 years, with special focus on highly innovative features introduced by nanotechnology. As the literature in rather extensive, we try to simplify this work by summarizing and grouping electrochemical sensors according to the manner their substrates were chemically modified. We also discuss the current and future

  3. HIGHWAY INFRASTRUCTURE FOCUS AREA NEXT-GENERATION INFRASTRUCTURE MATERIALS VOLUME I - TECHNICAL PROPOSAL & MANAGEMENTENHANCEMENT OF TRANSPORTATION INFRASTRUCTURE WITH IRON-BASED AMORPHOUS-METAL AND CERAMIC COATINGS

    SciTech Connect

    Farmer, J C

    2007-12-04

    The infrastructure for transportation in the United States allows for a high level of mobility and freight activity for the current population of 300 million residents, and several million business establishments. According to a Department of Transportation study, more than 230 million motor vehicles, ships, airplanes, and railroads cars were used on 6.4 million kilometers (4 million miles) of highways, railroads, airports, and waterways in 1998. Pipelines and storage tanks were considered to be part of this deteriorating infrastructure. The annual direct cost of corrosion in the infrastructure category was estimated to be approximately $22.6 billion in 1998. There were 583,000 bridges in the United States in 1998. Of this total, 200,000 bridges were steel, 235,000 were conventional reinforced concrete, 108,000 bridges were constructed using pre-stressed concrete, and the balance was made using other materials of construction. Approximately 15 percent of the bridges accounted for at this point in time were structurally deficient, primarily due to corrosion of steel and steel reinforcement. Iron-based amorphous metals, including SAM2X5 (Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4}) and SAM1651 (Fe{sub 48}Mo{sub 14}Cr{sub 15}Y{sub 2}C{sub 15}B{sub 6}) have been developed, and have very good corrosion resistance. These materials have been prepared as a melt-spun ribbons, as well as gas atomized powders and thermal-spray coatings. During electrochemical testing in several environments, including seawater at 90 C, the passive film stabilities of these materials were found to be comparable to that of more expensive high-performance alloys, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. These materials also performed very well in standard salt fog tests. Chromium (Cr), molybdenum (Mo) and tungsten (W) provided corrosion resistance, and boron (B) enabled glass formation

  4. Nod Factor Effects on Root Hair-Specific Transcriptome of Medicago truncatula: Focus on Plasma Membrane Transport Systems and Reactive Oxygen Species Networks

    PubMed Central

    Damiani, Isabelle; Drain, Alice; Guichard, Marjorie; Balzergue, Sandrine; Boscari, Alexandre; Boyer, Jean-Christophe; Brunaud, Véronique; Cottaz, Sylvain; Rancurel, Corinne; Da Rocha, Martine; Fizames, Cécile; Fort, Sébastien; Gaillard, Isabelle; Maillol, Vincent; Danchin, Etienne G. J.; Rouached, Hatem; Samain, Eric; Su, Yan-Hua; Thouin, Julien; Touraine, Bruno; Puppo, Alain; Frachisse, Jean-Marie; Pauly, Nicolas; Sentenac, Hervé

    2016-01-01

    Root hairs are involved in water and nutrient uptake, and thereby in plant autotrophy. In legumes, they also play a crucial role in establishment of rhizobial symbiosis. To obtain a holistic view of Medicago truncatula genes expressed in root hairs and of their regulation during the first hours of the engagement in rhizobial symbiotic interaction, a high throughput RNA sequencing on isolated root hairs from roots challenged or not with lipochitooligosaccharides Nod factors (NF) for 4 or 20 h was carried out. This provided a repertoire of genes displaying expression in root hairs, responding or not to NF, and specific or not to legumes. In analyzing the transcriptome dataset, special attention was paid to pumps, transporters, or channels active at the plasma membrane, to other proteins likely to play a role in nutrient ion uptake, NF electrical and calcium signaling, control of the redox status or the dynamic reprogramming of root hair transcriptome induced by NF treatment, and to the identification of papilionoid legume-specific genes expressed in root hairs. About 10% of the root hair expressed genes were significantly up- or down-regulated by NF treatment, suggesting their involvement in remodeling plant functions to allow establishment of the symbiotic relationship. For instance, NF-induced changes in expression of genes encoding plasma membrane transport systems or disease response proteins indicate that root hairs reduce their involvement in nutrient ion absorption and adapt their immune system in order to engage in the symbiotic interaction. It also appears that the redox status of root hair cells is tuned in response to NF perception. In addition, 1176 genes that could be considered as “papilionoid legume-specific” were identified in the M. truncatula root hair transcriptome, from which 141 were found to possess an ortholog in every of the six legume genomes that we considered, suggesting their involvement in essential functions specific to legumes. This

  5. Nod Factor Effects on Root Hair-Specific Transcriptome of Medicago truncatula: Focus on Plasma Membrane Transport Systems and Reactive Oxygen Species Networks.

    PubMed

    Damiani, Isabelle; Drain, Alice; Guichard, Marjorie; Balzergue, Sandrine; Boscari, Alexandre; Boyer, Jean-Christophe; Brunaud, Véronique; Cottaz, Sylvain; Rancurel, Corinne; Da Rocha, Martine; Fizames, Cécile; Fort, Sébastien; Gaillard, Isabelle; Maillol, Vincent; Danchin, Etienne G J; Rouached, Hatem; Samain, Eric; Su, Yan-Hua; Thouin, Julien; Touraine, Bruno; Puppo, Alain; Frachisse, Jean-Marie; Pauly, Nicolas; Sentenac, Hervé

    2016-01-01

    Root hairs are involved in water and nutrient uptake, and thereby in plant autotrophy. In legumes, they also play a crucial role in establishment of rhizobial symbiosis. To obtain a holistic view of Medicago truncatula genes expressed in root hairs and of their regulation during the first hours of the engagement in rhizobial symbiotic interaction, a high throughput RNA sequencing on isolated root hairs from roots challenged or not with lipochitooligosaccharides Nod factors (NF) for 4 or 20 h was carried out. This provided a repertoire of genes displaying expression in root hairs, responding or not to NF, and specific or not to legumes. In analyzing the transcriptome dataset, special attention was paid to pumps, transporters, or channels active at the plasma membrane, to other proteins likely to play a role in nutrient ion uptake, NF electrical and calcium signaling, control of the redox status or the dynamic reprogramming of root hair transcriptome induced by NF treatment, and to the identification of papilionoid legume-specific genes expressed in root hairs. About 10% of the root hair expressed genes were significantly up- or down-regulated by NF treatment, suggesting their involvement in remodeling plant functions to allow establishment of the symbiotic relationship. For instance, NF-induced changes in expression of genes encoding plasma membrane transport systems or disease response proteins indicate that root hairs reduce their involvement in nutrient ion absorption and adapt their immune system in order to engage in the symbiotic interaction. It also appears that the redox status of root hair cells is tuned in response to NF perception. In addition, 1176 genes that could be considered as "papilionoid legume-specific" were identified in the M. truncatula root hair transcriptome, from which 141 were found to possess an ortholog in every of the six legume genomes that we considered, suggesting their involvement in essential functions specific to legumes. This

  6. Microstructural analysis and transport properties of MoO and MoC nanostructures prepared by focused electron beam-induced deposition.

    PubMed

    Makise, Kazumasa; Mitsuishi, Kazutaka; Shimojo, Masayuki; Shinozaki, Bunju

    2014-07-18

    By electron-beam-induced deposition, we have succeeded in the direct fabrication of nanowires of molybdenum oxide (MoOx) and molybdenum carbide (MoC) on a SiO2 substrate set in a scanning electron microscope. In order to prepare MoOx specimens of high purity, a precursor gas of molybdenum hexacarbonyl [Mo(CO)6] is used, mixed with oxygen gas. On the other hand, MoC is grown by mixing H2O gas with the precursor gas. The electrical transport properties of the nanowires are investigated by the DC four-terminal method. A highly resistive MoOx nanowire prepared from an as-deposited specimen by annealing in air shows nonlinear current-voltage characteristics and a high photoconductivity. The resistivity ρ of an as-deposited amorphous MoC (a-MoC) nanowire takes its maximum at a temperature T ≈ 10 K and decreases to ≈ 0 with decreasing temperature. This behavior of ρ(T) indicates the possible occurrence of superconductivity in a-MoC nanowires. The characteristic of ρ(T) below the superconducting transition temperature Tc ≈ 4 K can be well explained by the quantum phase-slip model with a coherence length ξ(0) ≈ 8 nm at T = 0.

  7. Microstructural analysis and Transport Properties of MoO and MoC nanostructures prepared by focused electron beam-induced deposition

    PubMed Central

    Makise, Kazumasa; Mitsuishi, Kazutaka; Shimojo, Masayuki; Shinozaki, Bunju

    2014-01-01

    By electron-beam-induced deposition, we have succeeded in the direct fabrication of nanowires of molybdenum oxide (MoOx) and molybdenum carbide (MoC) on a SiO2 substrate set in a scanning electron microscope. In order to prepare MoOx specimens of high purity, a precursor gas of molybdenum hexacarbonyl [Mo(CO)6] is used, mixed with oxygen gas. On the other hand, MoC is grown by mixing H2O gas with the precursor gas. The electrical transport properties of the nanowires are investigated by the DC four-terminal method. A highly resistive MoOx nanowire prepared from an as-deposited specimen by annealing in air shows nonlinear current-voltage characteristics and a high photoconductivity. The resistivity ρ of an as-deposited amorphous MoC (a-MoC) nanowire takes its maximum at a temperature T ≈ 10 K and decreases to ≈ 0 with decreasing temperature. This behavior of ρ(T) indicates the possible occurrence of superconductivity in a-MoC nanowires. The characteristic of ρ(T) below the superconducting transition temperature Tc ≈ 4 K can be well explained by the quantum phase-slip model with a coherence length ξ(0) ≈ 8 nm at T = 0. PMID:25033894

  8. Microstructural analysis and Transport Properties of MoO and MoC nanostructures prepared by focused electron beam-induced deposition

    NASA Astrophysics Data System (ADS)

    Makise, Kazumasa; Mitsuishi, Kazutaka; Shimojo, Masayuki; Shinozaki, Bunju

    2014-07-01

    By electron-beam-induced deposition, we have succeeded in the direct fabrication of nanowires of molybdenum oxide (MoOx) and molybdenum carbide (MoC) on a SiO2 substrate set in a scanning electron microscope. In order to prepare MoOx specimens of high purity, a precursor gas of molybdenum hexacarbonyl [Mo(CO)6] is used, mixed with oxygen gas. On the other hand, MoC is grown by mixing H2O gas with the precursor gas. The electrical transport properties of the nanowires are investigated by the DC four-terminal method. A highly resistive MoOx nanowire prepared from an as-deposited specimen by annealing in air shows nonlinear current-voltage characteristics and a high photoconductivity. The resistivity ρ of an as-deposited amorphous MoC (a-MoC) nanowire takes its maximum at a temperature T ~ 10 K and decreases to ~ 0 with decreasing temperature. This behavior of ρ(T) indicates the possible occurrence of superconductivity in a-MoC nanowires. The characteristic of ρ(T) below the superconducting transition temperature Tc ~ 4 K can be well explained by the quantum phase-slip model with a coherence length ξ(0) ~ 8 nm at T = 0.

  9. Pulsed Laser-Assisted Focused Electron-Beam-Induced Etching of Titanium with XeF 2 : Enhanced Reaction Rate and Precursor Transport

    DOE PAGES

    Noh, J. H.; Fowlkes, J. D.; Timilsina, R.; ...

    2015-01-28

    We introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing; we do this in order to enhance the etch rate of electron-beam-induced etching. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. Moreover, the evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. Finally, the increased etch rate is attributed to photothermally enhancedmore » Ti–F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.« less

  10. Pulsed Laser-Assisted Focused Electron-Beam-Induced Etching of Titanium with XeF 2 : Enhanced Reaction Rate and Precursor Transport

    SciTech Connect

    Noh, J. H.; Fowlkes, J. D.; Timilsina, R.; Stanford, M. G.; Lewis, B. B.; Rack, P. D.

    2015-01-28

    We introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing; we do this in order to enhance the etch rate of electron-beam-induced etching. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. Moreover, the evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. Finally, the increased etch rate is attributed to photothermally enhanced Ti–F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.

  11. Pulsed laser-assisted focused electron-beam-induced etching of titanium with XeF2: enhanced reaction rate and precursor transport.

    PubMed

    Noh, J H; Fowlkes, J D; Timilsina, R; Stanford, M G; Lewis, B B; Rack, P D

    2015-02-25

    In order to enhance the etch rate of electron-beam-induced etching, we introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. The evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. The increased etch rate is attributed to photothermally enhanced Ti-F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.

  12. Enkephalin co-expression with classic neurotransmitters in the amygdaloid complex of the rat.

    PubMed

    Poulin, Jean-François; Castonguay-Lebel, Zoé; Laforest, Sylvie; Drolet, Guy

    2008-02-20

    This study aimed at characterizing the neurotransmitter phenotype of enkephalin neurons in the rat amygdaloid complex. We first established the detailed distribution of vesicular glutamate transporters 1 and 2 (VGLUT1 and -2) and glutamate decarboxylase 65 (GAD65) in the amygdala by using in situ hybridization. In the amygdaloid complex, GAD65 is strongly expressed in striatal-like divisions, namely, the anterior amygdaloid area, the central nucleus (CEA), the intercalated nuclei, and the dorsal part of the medial nucleus (MEA). VGLUT1 and -2 expression is mostly segregated to specific divisions of the amygdale, with VGLUT2 being expressed only in the MEA, the anterior cortical nucleus (COAa), and the anterior basomedial nucleus (BMAa), whereas VGLUT1 is expressed in all other divisions of the amygdala. Second, we assessed the co-expression of preproenkephalin (ppENK) with GAD65, VGLUT1, or VGLUT2 by using double fluorescent in situ hybridization. We found that ppENK mRNA co-localized exclusively with GAD65 in all striatal-like structures of the amygdaloid complex with the exception of the MEA, where ENK also co-localized with VGLUT2 mRNA. This co-localization is most apparent in the posteroventral part of the MEA, where 70% of ENKergic cells expressed VGLUT2. In addition, ppENK also co-localized with VGLUT1 because more than 95% of ENK cells in the basolateral amygdala expressed VGLUT1. In contrast, less than 25% of ENKergic cells expressed VGLUT1 in the lateral nucleus of the amygdale, with the majority of ENK cells expressing GAD65 mRNA in this nucleus. These results have broad implications for understanding the functional roles of enkephalinergic neurotransmission in the amygdaloid complex.

  13. Neurotransmitter regulation of circadian structural changes in the fly's visual system.

    PubMed

    Meinertzhagen, I A; Pyza, E

    1999-04-15

    The visual system of the fly's compound eye undergoes a number of cyclical day/night changes that have a circadian basis. Such responses are seen in the synaptic terminals of the photoreceptors and in their large monopolar-cell interneurons in the first optic neuropile, or lamina. These changes include, in the photoreceptor terminals, rhythms in the numbers of synapses and the vertical migration of screening pigment; and, in the monopolar cells L1 and L2, a rhythm in the transients of the electroretinogram and in the cyclical swelling of L1 and L2 lamina axons, as well as of the epithelial glia that surround these. Some of these changes are seen in both the housefly and the fruit fly, but the time-course of such changes differs between the two species. Many of the changes are influenced by the injection of various transmitter candidates, in a direction that can be reconciled with the possibility of normal endogenous release of two substances, 5HT from the neurites of 5HT-immunoreactive neurons, and pigment dispersing factor peptide from the neurites of PDH cells. Consistent with this interpretation, the immunoreactive varicosities of PDH cells exhibit size changes attributable to their cyclical release of peptide, or to its cyclical synthesis and/or transport from the PDH cell somata. Thus, neurotransmitter substances not only have rapid electrophysiological actions in the optic lobe, but also longer-lasting, presumably indirect, neuromodulatory actions, which are manifest as structural changes among the lamina's neurons and synapses. These actions involve an interplay between aminergic and peptidergic systems, but the exact role and especially the site of action of each has still to be elucidated.

  14. Evidence for histamine as a neurotransmitter in the cardiac sympathetic nervous system.

    PubMed

    Li, Mingkai; Hu, Jing; Chen, Zhong; Meng, Jia; Wang, Haifang; Ma, Xue; Luo, Xiaoxing

    2006-07-01

    The colocalization of histamine (HA) and norepinephrine (NE) immunoreactivities was identified within the superior cervical ganglia neurons of the guinea pig. HA and NE immunoreactivity levels were significantly attenuated after chemical sympathectomy with 6-hydroxydopamine (6-OHDA). Coexistence of NE and HA was also visualized in the cardiac sympathetic axon and varicosities labeled with anterograde tracer biotinylated dextran amine. Depolarization of cardiac sympathetic nerve endings (synaptosomes) with 50 mM potassium stimulated endogenous HA release, which was significantly attenuated by 6-OHDA or a vesicular monoamine transporter 2 (VMAT2) inhibitor reserpine pretreatments. Compound 48/80, a mast cell releaser, did not affect cardiac synaptosome HA exocytosis. Furthermore, K+ -evoked HA release was abolished by the N-type Ca2+ -channel blocker omega-conotoxin but was not affected by the L-type Ca2+ -channel blocker lacidipine. Cardiac synaptosome HA exocytosis was augmented by the enhanced synthesis of HA or the inhibition of HA metabolism. HA H3-receptor activation by (R)-alpha-methylhistamine inhibited high K+ -evoked histamine release. The HA H3 receptor antagonist thioperamide enhanced K+ -evoked HA release and blocked the (R)-alpha-methylhistamine effect. The K+ -evoked endogenous NE release was attenuated by preloading the cardiac synaptosomes with L-histidine or quinacrine. These inhibitory effects were reversed by thioperamide or antagonized by alpha-fluoromethylhistidine. Our findings indicate that high K+ -evoked corelease of NE and HA may be inhibited by endogenous HA via activation of presynaptic HA H3-receptors. The H3-receptor may function as an autoreceptor, rather than a heteroreceptor, in the regulation of sympathetic neurotransmission and HA may be a novel sympathetic neurotransmitter.

  15. Effects of cognitive-behavioral therapy on Eating Disorders: neurotransmitter secretory response to treatment.

    PubMed

    Brambilla, F; Dalle Grave, R; Calugi, S; Marchesini, G; Baroni, S; Marazziti, D

    2010-06-01

    The effects of cognitive-behavioral therapy (CBT) on central dopamine (DA), noradrenaline (NE) and serotonin (5-HT) secretion were studied in a group of 50 female inpatients, of which 14 suffered from anorexia nervosa restricted type (AN-R), 14 from anorexia nervosa bingeing-purging type (AN-BP), and 22 from bulimia nervosa (BN). The aim of the study was to see whether or not CBT modifies the secretion of central DA (blood homovanillic acid=HVA), NE (blood 3-methoxy-4-hydroxy-phenylglycol=MHPG) and the 5-HT transporter (as evaluated by the platelet paroxetine binding=[(3)H]-Par-binding), if the physical and psychological effects of CBT correlate with changes of the neurotransmitter secretion; and if the biological effects of CBT are linked to specific psychopathological aspect of the disorders. The treatment lasted 20 weeks. Body-mass Index, bingeing and purging, specific AN-BN psychopathological (EDE 12-OD), depression (Beck Inventory), anxiety (STAY Form-Y-1), impulsiveness (Barratt Impulsiveness Scale), self-esteem (Rosenberg Self-Biochemical Scale) and temperament (Temperament and Character Inventory, Cloninger Scale) were assessed at baseline and at the end of the treatment. CBT significantly improved the psychophysical aspects of the diseases. HVA and MHPG concentrations did not change. The [(3)H]-Par-binding parameters, the maximum binding capacity (B(max)) and dissociation constant (K(d)) values did not change in either AN-R or AN-BP patients, while the [(3)H]-Par B(max) (and not the K(d)) increased significantly in BN patients. Correlations emerged between basal and final [(3)H]-Par B(max) values and psychopathological scores, but not between CBT-induced differences between basal and final values. Our data suggest that only in BN CBT may act through changes in 5-HT system function.

  16. Transverse field focused system

    DOEpatents

    Anderson, Oscar A.

    1986-01-01

    A transverse field focused (TFF) system for transport or acceleration of an intense sheet beam of negative ions in which a serial arrangement of a plurality of pairs of concentric cylindrical-arc electrodes is provided. Acceleration of the sheet beam can be achieved by progressively increasing the mean electrode voltage of successive electrode pairs. Because the beam is curved by the electrodes, the system can be designed to transport the beam through a maze passage which is baffled to prevent line of sight therethrough. Edge containment of the beam can be achieved by shaping the side edges of the electrodes to produce an electric force vector directed inwardly from the electrode edges.

  17. The solute carrier 6 family of transporters

    PubMed Central

    Bröer, Stefan; Gether, Ulrik

    2012-01-01

    The solute carrier 6 (SLC6) family of the human genome comprises transporters for neurotransmitters, amino acids, osmolytes and energy metabolites. Members of this family play critical roles in neurotransmission, cellular and whole body homeostasis. Malfunction or altered expression of these transporters is associated with a variety of diseases. Pharmacological inhibition of the neurotransmitter transporters in this family is an important strategy in the management of neurological and psychiatric disorders. This review provides an overview of the biochemical and pharmacological properties of the SLC6 family transporters. LINKED ARTICLES BJP published a themed section on Transporters in 2011. To view articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.2011.164.issue-7/issuetoc PMID:22519513

  18. Decomposing the profile of PM in two low polluted German cities--mapping of air mass residence time, focusing on potential long range transport impacts.

    PubMed

    Dimitriou, Konstantinos; Kassomenos, Pavlos

    2014-07-01

    This paper aims to decompose the profile of particulates in Karlsruhe and Potsdam (Germany), focusing on the localization of PM potential transboundary sources. An air mass cluster analysis was implemented, followed by a study of air mass residence time on a grid of a 0.5° × 0.5° resolution. Particulate/gaseous daily air pollution and meteorological data were used to indicate PM local sources. Four Principal Component Analysis (PCA) components were produced: traffic, photochemical, industrial/domestic and particulate. PM2.5/PM10 ratio seasonal trends, indicated production of PMCOARSE (PM10-PM2.5) from secondary sources in Potsdam during warm period (WP). The residing areas of incoming slow moving air masses are potential transboundary PM sources. For Karlsruhe those areas were mainly around the city. An air mass residence time secondary peak was observed over Stuttgart. For Potsdam, areas with increased dwelling time of the arriving air parcels were detected particularly above E/SE Germany.

  19. Recent progress and challenges in nanotechnology for biomedical applications: an insight into the analysis of neurotransmitters.

    PubMed

    Shankaran, Dhesingh Ravi; Miura, Norio

    2007-01-01

    Nanotechnology offers exciting opportunities and unprecedented compatibilities in manipulating chemical and biological materials at the atomic or molecular scale for the development of novel functional materials with enhanced capabilities. It plays a central role in the recent technological advances in biomedical technology, especially in the areas of disease diagnosis, drug design and drug delivery. In this review, we present the recent trend and challenges in the development of nanomaterials for biomedical applications with a special emphasis on the analysis of neurotransmitters. Neurotransmitters are the chemical messengers which transform information and signals all over the body. They play prime role in functioning of the central nervous system (CNS) and governs most of the metabolic functions including movement, pleasure, pain, mood, emotion, thinking, digestion, sleep, addiction, fear, anxiety and depression. Thus, development of high-performance and user-friendly analytical methods for ultra-sensitive detection of neurotransmitters remain a major challenge in modern biomedical analysis. Nanostructured materials are emerging as a powerful mean for diagnosis of CNS disorders because of their unique optical, size and surface characteristics. This review provides a brief outline on the basic concepts and recent advancements of nanotechnology for biomedical applications, especially in the analysis of neurotransmitters. A brief introduction to the nanomaterials, bionanotechnology and neurotransmitters is also included along with discussions on most of the patents published in these areas.

  20. Electrophoretic Focusing

    NASA Technical Reports Server (NTRS)

    Snyder, Robert S.

    2001-01-01

    Electrophoretic focusing is a new method of continuous flow electrophoresis that introduces precision flow control to achieve high resolution separations. The electric field is applied perpendicular to an incoming sample lamina and buffer but also perpendicular to the broad faces of the thin rectangular chamber. A uniform fluid cross-flow then enters and exits the separation chamber through the same broad faces which are porous. A balance is achieved by adjusting either the electric field or the cross-flow so the desired sample fraction with its specific migration velocity encounters an opposing flow of the same velocity. Applying an electric field transverse to the incoming sample lamina and opposing this field with a carefully configured buffer flow, a sample constituent can be selected and focused into a narrow stream for subsequent analysis. Monotonically changing either electric field or buffer cross-flow will yield a scan of all constituents of the sample. Stopping the scan increases the collection time for minor constituents to improve their analysis. Using the high voltage gradients and/or cross-flow to rapidly deflect extraneous sample through the porous screens and into either of the side (purge) chambers, the selected sample is focused in the center plane of the separation chamber and collected without contact or interaction with the separation chamber walls. Results will be presented on the separation of a range of materials including dyes, proteins, and monodisperse polystyrene latexes. Sources of sample dispersion inherent in other electrokinetic techniques will be shown to be negligible for a variety of sample concentrations, buffer properties and operating conditions.

  1. Transport Phenomena.

    ERIC Educational Resources Information Center

    McCready, Mark J.; Leighton, David T.

    1987-01-01

    Discusses the problems created in graduate chemical engineering programs when students enter with a wide diversity of understandings of transport phenomena. Describes a two-semester graduate transport course sequence at the University of Notre Dame which focuses on fluid mechanics and heat and mass transfer. (TW)

  2. Pharmacogenomics in psychiatry: the relevance of receptor and transporter polymorphisms.

    PubMed

    Reynolds, Gavin P; McGowan, Olga O; Dalton, Caroline F

    2014-04-01

    The treatment of severe mental illness, and of psychiatric disorders in general, is limited in its efficacy and tolerability. There appear to be substantial interindividual differences in response to psychiatric drug treatments that are generally far greater than the differences between individual drugs; likewise, the occurrence of adverse effects also varies profoundly between individuals. These differences are thought to reflect, at least in part, genetic variability. The action of psychiatric drugs primarily involves effects on synaptic neurotransmission; the genes for neurotransmitter receptors and transporters have provided strong candidates in pharmacogenetic research in psychiatry. This paper reviews some aspects of the pharmacogenetics of neurotransmitter receptors and transporters in the treatment of psychiatric disorders. A focus on serotonin, catecholamines and amino acid transmitter systems reflects the direction of research efforts, while relevant results from some genome-wide association studies are also presented. There are many inconsistencies, particularly between candidate gene and genome-wide association studies. However, some consistency is seen in candidate gene studies supporting established pharmacological mechanisms of antipsychotic and antidepressant response with associations of functional genetic polymorphisms in, respectively, the dopamine D2 receptor and serotonin transporter and receptors. More recently identified effects of genes related to amino acid neurotransmission on the outcome of treatment of schizophrenia, bipolar illness or depression reflect the growing understanding of the roles of glutamate and γ-aminobutyric acid dysfunction in severe mental illness. A complete understanding of psychiatric pharmacogenomics will also need to take into account epigenetic factors, such as DNA methylation, that influence individual responses to drugs.

  3. Pharmacogenomics in psychiatry: the relevance of receptor and transporter polymorphisms

    PubMed Central

    Reynolds, Gavin P; McGowan, Olga O; Dalton, Caroline F

    2014-01-01

    The treatment of severe mental illness, and of psychiatric disorders in general, is limited in its efficacy and tolerability. There appear to be substantial interindividual differences in response to psychiatric drug treatments that are generally far greater than the differences between individual drugs; likewise, the occurrence of adverse effects also varies profoundly between individuals. These differences are thought to reflect, at least in part, genetic variability. The action of psychiatric drugs primarily involves effects on synaptic neurotransmission; the genes for neurotransmitter receptors and transporters have provided strong candidates in pharmacogenetic research in psychiatry. This paper reviews some aspects of the pharmacogenetics of neurotransmitter receptors and transporters in the treatment of psychiatric disorders. A focus on serotonin, catecholamines and amino acid transmitter systems reflects the direction of research efforts, while relevant results from some genome-wide association studies are also presented. There are many inconsistencies, particularly between candidate gene and genome-wide association studies. However, some consistency is seen in candidate gene studies supporting established pharmacological mechanisms of antipsychotic and antidepressant response with associations of functional genetic polymorphisms in, respectively, the dopamine D2 receptor and serotonin transporter and receptors. More recently identified effects of genes related to amino acid neurotransmission on the outcome of treatment of schizophrenia, bipolar illness or depression reflect the growing understanding of the roles of glutamate and γ-aminobutyric acid dysfunction in severe mental illness. A complete understanding of psychiatric pharmacogenomics will also need to take into account epigenetic factors, such as DNA methylation, that influence individual responses to drugs. PMID:24354796

  4. Hindbrain lactostasis regulates hypothalamic AMPK activity and metabolic neurotransmitter mRNA and protein responses to hypoglycemia.

    PubMed

    Gujar, Amit D; Ibrahim, Baher A; Tamrakar, Pratistha; Cherian, Ajeesh Koshy; Briski, Karen P

    2014-04-01

    Nerve cell metabolic activity is monitored in multiple brain regions, including the hypothalamus and hindbrain dorsal vagal complex (DVC), but it is unclear if individual metabolosensory loci operate autonomously or interact to coordinate central nervous system (CNS) reactivity to energy imbalance. This research addressed the hypothesis that hypoglycemia-associated DVC lactoprivation stimulates hypothalamic AMPK activity and metabolic neurotransmitter expression. As DVC catecholaminergic neurons express biomarkers for metabolic monitoring, we investigated whether these cells are a source of lactate deficit signaling to the hypothalamus. Caudal fourth ventricle (CV4) infusion of the glucose metabolite l-lactate during insulin-induced hypoglycemia reversed changes in DVC A2 noradrenergic, arcuate neuropeptide Y (NPY) and pro-opiomelanocortin (POMC), and lateral hypothalamic orexin-A (ORX) neuronal AMPK activity, coincident with exacerbation of hypoglycemia. Hindbrain lactate repletion also blunted hypoglycemic upregulation of arcuate NPY mRNA and protein. This treatment did not alter hypoglycemic paraventricular oxytocin (OT) and lateral hypothalamic ORX mRNA profiles, but exacerbated or reversed adjustments in OT and ORX neuropeptide synthesis, respectively. CV4 delivery of the monocarboxylate transporter inhibitor, 4-CIN, increased A2 phosphoAMPK (pAMPK), elevated circulating glucose, and stimulated feeding, responses that were attenuated by 6-hydroxydopamine pretreatment. 4-CIN-infused rats exhibited increased (NPY, ORX neurons) or decreased (POMC neurons) pAMPK concurrent with hyperglycemia. These data show that hindbrain lactoprivic signaling regulates hypothalamic AMPK and key effector neurotransmitter responses to hypoglycemia. Evidence that A2 AMPK activity is lactate-dependent, and that DVC catecholamine cells are critical for lactoprivic control of glucose, feeding, and hypothalamic AMPK, implies A2 derivation of this metabolic regulatory stimulus.

  5. Frontal cortex and hippocampus neurotransmitter receptor complex level parallels spatial memory performance in the radial arm maze.

    PubMed

    Shanmugasundaram, Bharanidharan; Sase, Ajinkya; Miklosi, András G; Sialana, Fernando J; Subramaniyan, Saraswathi; Aher, Yogesh D; Gröger, Marion; Höger, Harald; Bennett, Keiryn L; Lubec, Gert

    2015-08-01

    Several neurotransmitter receptors have been proposed to be involved in memory formation. However, information on receptor complexes (RCs) in the radial arm maze (RAM) is missing. It was therefore the aim of this study to determine major neurotransmitter RCs levels that are modulated by RAM training because receptors are known to work in homo-or heteromeric assemblies. Immediate early gene Arc expression was determined by immunohistochemistry to show if prefrontal cortices (PFC) and hippocampi were activated following RAM training as these regions are known to be mainly implicated in spatial memory. Twelve rats per group, trained and untrained in the twelve arm RAM were used, frontal cortices and hippocampi were taken, RCs in membrane protein were quantified by blue-native PAGE immunoblotting. RCs components were characterised by co-immunoprecipitation followed by mass spectrometrical analysis and by the use of the proximity ligation assay. Arc expression was significantly higher in PFC of trained as compared to untrained rats whereas it was comparable in hippocampi. Frontal cortical levels of RCs containing AMPA receptors GluA1, GluA2, NMDA receptors GluN1 and GluN2A, dopamine receptor D1, acetylcholine nicotinic receptor alpha 7 (nAChR-α7) and hippocampal levels of RCs containing D1, GluN1, GluN2B and nAChR-α7 were increased in the trained group; phosphorylated dopamine transporter levels were decreased in the trained group. D1 and GluN1 receptors were shown to be in the same complex. Taken together, distinct RCs were paralleling performance in the RAM which is relevant for interpretation of previous and design of future work on RCs in memory studies.

  6. SLC1 Glutamate Transporters

    PubMed Central

    Grewer, Christof; Gameiro, Armanda; Rauen, Thomas

    2014-01-01

    The plasma membrane transporters for the neurotransmitter glutamate belong to the solute carrier 1 (SLC1) family. They are secondary active transporters, taking up glutamate into the cell against a substantial concentration gradient. The driving force for concentrative uptake is provided by the cotransport of Na+ ions and the countertransport of one K+ in a step independent of the glutamate translocation step. Due to eletrogenicity of transport, the transmembrane potential can also act as a driving force. Glutamate transporters are expressed in many tissues, but are of particular importance in the brain, where they contribute to the termination of excitatory neurotransmission. Glutamate transporters can also run in reverse, resulting in glutamate release from cells. Due to these important physiological functions, glutamate transporter expression and, therefore, the transport rate, are tightly regulated. This review summarizes recent literature on the functional and biophysical properties, structure-function relationships, regulation, physiological significance, and pharmacology of glutamate transporters. Particular emphasis is on the insight from rapid kinetic and electrophysiological studies, transcriptional regulation of transporter expression, and reverse transport and its importance for pathophysiological glutamate release under ischemic conditions. PMID:24240778

  7. Protons are a neurotransmitter that regulates synaptic plasticity in the lateral amygdala.

    PubMed

    Du, Jianyang; Reznikov, Leah R; Price, Margaret P; Zha, Xiang-ming; Lu, Yuan; Moninger, Thomas O; Wemmie, John A; Welsh, Michael J

    2014-06-17

    Stimulating presynaptic terminals can increase the proton concentration in synapses. Potential receptors for protons are acid-sensing ion channels (ASICs), Na(+)- and Ca(2+)-permeable channels that are activated by extracellular acidosis. Those observations suggest that protons might be a neurotransmitter. We found that presynaptic stimulation transiently reduced extracellular pH in the amygdala. The protons activated ASICs in lateral amygdala pyramidal neurons, generating excitatory postsynaptic currents. Moreover, both protons and ASICs were required for synaptic plasticity in lateral amygdala neurons. The results identify protons as a neurotransmitter, and they establish ASICs as the postsynaptic receptor. They also indicate that protons and ASICs are a neurotransmitter/receptor pair critical for amygdala-dependent learning and memory.

  8. Differential stimulation of the retina with subretinally injected exogenous neurotransmitter: A biomimetic alternative to electrical stimulation

    NASA Astrophysics Data System (ADS)

    Rountree, Corey M.; Inayat, Samsoon; Troy, John B.; Saggere, Laxman

    2016-12-01

    Subretinal stimulation of the retina with neurotransmitters, the normal means of conveying visual information, is a potentially better alternative to electrical stimulation widely used in current retinal prostheses for treating blindness from photoreceptor degenerative diseases. Yet, no subretinal electrical or chemical stimulation study has stimulated the OFF and ON pathways differentially through inner retinal activation. Here, we demonstrate the feasibility of differentially stimulating retinal ganglion cells (RGCs) through the inner nuclear layer of the retina with glutamate, a primary neurotransmitter chemical, in a biomimetic way. We show that controlled pulsatile delivery of glutamate into the subsurface of explanted wild-type rat retinas elicits highly localized simultaneous inhibitory and excitatory spike rate responses in OFF and ON RGCs. We also present the spatiotemporal characteristics of RGC responses to subretinally injected glutamate and the therapeutic stimulation parameters. Our findings could pave the way for future development of a neurotransmitter-based subretinal prosthesis offering more naturalistic vision and better visual acuity than electrical prostheses.

  9. Neurotransmitter Specific, Cellular-Resolution Functional Brain Mapping Using Receptor Coated Nanoparticles: Assessment of the Possibility

    PubMed Central

    Forati, Ebrahim; Sabouni, Abas; Ray, Supriyo; Head, Brian; Schoen, Christian; Sievenpiper, Dan

    2015-01-01

    Receptor coated resonant nanoparticles and quantum dots are proposed to provide a cellular-level resolution image of neural activities inside the brain. The functionalized nanoparticles and quantum dots in this approach will selectively bind to different neurotransmitters in the extra-synaptic regions of neurons. This allows us to detect neural activities in real time by monitoring the nanoparticles and quantum dots optically. Gold nanoparticles (GNPs) with two different geometries (sphere and rod) and quantum dots (QDs) with different sizes were studied along with three different neurotransmitters: dopamine, gamma-Aminobutyric acid (GABA), and glycine. The absorption/emission spectra of GNPs and QDs before and after binding of neurotransmitters and their corresponding receptors are reported. The results using QDs and nanorods with diameter 25nm and aspect rations larger than three were promising for the development of the proposed functional brain mapping approach. PMID:26717196

  10. Convergent Pathways for Steroid Hormone-and Neurotransmitter-Induced Rat Sexual Behavior

    NASA Astrophysics Data System (ADS)

    Mani, S. K.; Allen, J. M. C.; Clark, J. H.; Blaustein, J. D.; O'Malley, B. W.

    1994-08-01

    Estrogen and progesterone modulate gene expression in rodents by activation of intracellular receptors in the hypothalamus, which regulate neuronal networks that control female sexual behavior. However, the neurotransmitter dopamine has been shown to activate certain steroid receptors in a ligand-independent manner. A dopamine receptor stimulant and a D_1 receptor agonist, but not a D_2 receptor agonist, mimicked the effects of progesterone in facilitating sexual behavior in female rats. The facilitatory effect of the neurotransmitter was blocked by progesterone receptor antagonists, a D_1 receptor antagonist, or antisense oligonucleotides to the progesterone receptor. The results suggest that in rodents neurotransmitters may regulate in vivo gene expression and behavior by means of cross-talk with steroid receptors in the brain.

  11. Monoamine transporters: insights from molecular dynamics simulations

    PubMed Central

    Grouleff, Julie; Ladefoged, Lucy Kate; Koldsø, Heidi; Schiøtt, Birgit

    2015-01-01

    The human monoamine transporters (MATs) facilitate the reuptake of the neurotransmitters serotonin, dopamine, and norepinephrine from the synaptic cleft. Imbalance in monoaminergic neurotransmission is linked to various diseases including major depression, attention deficit hyperactivity disorder, schizophrenia, and Parkinson’s disease. Inhibition of the MATs is thus an important strategy for treatment of such diseases. The MATs are sodium-coupled transport proteins belonging to the neurotransmitter/Na+ symporter (NSS) family, and the publication of the first high-resolution structure of a NSS family member, the bacterial leucine transporter LeuT, in 2005, proved to be a major stepping stone for understanding this family of transporters. Structural data allows for the use of computational methods to study the MATs, which in turn has led to a number of important discoveries. The process of substrate translocation across the membrane is an intrinsically dynamic process. Molecular dynamics simulations, which can provide atomistic details of molecular motion on ns to ms timescales, are therefore well-suited for studying transport processes. In this review, we outline how molecular dynamics simulations have provided insight into the large scale motions associated with transport of the neurotransmitters, as well as the presence of external and internal gates, the coupling between ion and substrate transport, and differences in the conformational changes induced by substrates and inhibitors. PMID:26528185

  12. GABA Not Only a Neurotransmitter: Osmotic Regulation by GABAAR Signaling

    PubMed Central

    Cesetti, Tiziana; Ciccolini, Francesca; Li, Yuting

    2012-01-01

    Mature macroglia and almost all neural progenitor types express γ-aminobutyric (GABA) A receptors (GABAARs), whose activation by ambient or synaptic GABA, leads to influx or efflux of chloride (Cl−) depending on its electro-chemical gradient (ECl). Since the flux of Cl− is indissolubly associated to that of osmotically obliged water, GABAARs regulate water movements by modulating ion gradients. In addition, since water movements also occur through specialized water channels and transporters, GABAAR signaling could affect the movement of water by regulating the function of the channels and transporters involved, thereby affecting not only the direction of the water fluxes but also their dynamics. We will here review recent observations indicating that in neural cells GABAAR-mediated osmotic regulation affects the cellular volume thereby activating multiple intracellular signaling mechanisms important for cell proliferation, maturation, and survival. In addition, we will discuss evidence that the osmotic regulation exerted by GABA may contribute to brain water homeostasis in physiological and in pathological conditions causing brain edema, in which the GABAergic transmission is often altered. PMID:22319472

  13. A practical guide to the synthesis of dinitroindolinyl-caged neurotransmitters

    PubMed Central

    Ellis-Davies, Graham C R

    2014-01-01

    This protocol describes a method for efficient chemical synthesis of dinitroindolinyl derivatives of glutamate and gamma-aminobutyric acid. these caged neurotransmitters are currently the most chemically and photochemically efficient probes for two-photon photolysis in living brain slices. the protocol only requires basic organic synthesis equipment, and no silica gel column chromatography or NMR spectroscopy is needed at any stage. Hplc is used to purify the caged transmitters at the end of the syntheses. thus, the synthesis of dinitroindolinyl-caged neurotransmitters is within the scope of a modestly equipped chemistry laboratory. PMID:21372812

  14. Regulatory role of intracellular sodium ions in neurotransmitter secretion.

    PubMed

    Melinek, R; Lev-Tov, A; Meiri, H; Erulkar, S D; Rahamimoff, R

    1982-01-01

    Calcium ions are the main inducer of quantal transmitter release of the frog neuromuscular junction; but even in their virtual absence from the extracellular medium, nerve stimulation causes a prolonged augmentation of transmitter release. These facts led to the hypothesis that an accumulation of intracellular sodium can serve as a slow secondary regulator of neurosecretion. Three lines of evidence presented in this article substantiate this hypothesis: firstly, veratridine, which is known to increase sodium fluxes through the voltage-dependent sodium channels, increases transmitter release after nerve stimulation. Secondly, monensin, which was shown to induce sodium transport through nerve membranes, increases evoked transmitter release, tetanic potentiation and posttetanic potentiation. Thirdly, sodium-filled phosphatidylcholine liposomes increase transmitter release. These effects of sodium are probably not due to a direct effect on the transmitter release mechanism, but are caused by sodium-induced calcium translocation from intracellular stores.

  15. Treatment with Tyrosine a Neurotransmitter Precursor Reduces Environmental Stress in Humans

    DTIC Science & Technology

    1989-01-01

    brain norepinephrine and dopamine. catecholaminergic neurotransmitters. In animals, administration of tyrosine, a food constituent and precursor of the...Profile of Mood States. Stanford Sleepiness Scale) ENVIRONMENTAL STRESSORS that have been employed to evaluate a variety of psychoactive drugs foods ... tyramine . However. Plasma tyrosine levels were significantly elevated during behav- this amine is not detectable in the plasma of animals after they

  16. Neurotransmitter, peptide and cytokine processes in relation to depressive disorder: comorbidity between depression and neurodegenerative disorders.

    PubMed

    Anisman, Hymie; Merali, Zul; Hayley, Shawn

    2008-05-01

    Given the array of biological changes induced by stressors, it is not surprising that these experiences may provoke a variety of illnesses. Among others things, stressors promote functional changes of neuropeptide and classical neurotransmitter systems. The peptidergic changes, for instance, include alterations of corticotropin releasing hormone, arginine vasopressin, and bombesin-like peptides at specific brain sites. Similarly some of the neurotransmitter systems influenced by stressors include GABAergic and monoamine functioning. Variations of these processes may limit neurogenesis (and dysregulation of growth factors such as BDNF) and influence cellular viability (through NFkappaB and MAP kinase pathways). As well, stressors activate the inflammatory immune system, notably the release of signaling molecules (cytokines), which may provoke many of the same neuropeptide (and other neurotransmitter) changes. By virtue of their actions on neuronal functioning, inflammatory processes may influence stress-related illness, such as depression, and may be a common denominator for the comorbidity that exists between depression and neurological conditions, including Parkinson's and Alzheimer's diseases, as well as cardiovascular-related pathology. The present report provides an overview of biological endophenotypes associated with stressors that are thought to be related to major depressive disorder and related comorbid conditions. The view is taken that synergy between stressors and inflammatory factors may promote pathological outcomes through their actions on neuropeptides and several neurotransmitters. As well, stressful events may result in the sensitization of neurochemical and cytokine processes, so that later re-exposure to these stimuli may promote rapid and exaggerated responses that favor illness recurrence.

  17. Ectopic vesicular neurotransmitter release along sensory axons mediates neurovascular coupling via glial calcium signaling.

    PubMed

    Thyssen, Anne; Hirnet, Daniela; Wolburg, Hartwig; Schmalzing, Günther; Deitmer, Joachim W; Lohr, Christian

    2010-08-24

    Neurotransmitter release generally is considered to occur at active zones of synapses, and ectopic release of neurotransmitters has been demonstrated in a few instances. However, the mechanism of ectopic neurotransmitter release is poorly understood. We took advantage of the intimate morphological and functional proximity of olfactory receptor axons and specialized glial cells, olfactory ensheathing cells (OECs), to study ectopic neurotransmitter release. Axonal stimulation evoked purinergic and glutamatergic Ca(2+) responses in OECs, indicating ATP and glutamate release. In axons expressing synapto-pHluorin, stimulation evoked an increase in synapto-pHluorin fluorescence, indicative of vesicle fusion. Transmitter release was dependent on Ca(2+) and could be inhibited by bafilomycin A1 and botulinum toxin A. Ca(2+) transients in OECs evoked by ATP, axonal stimulation, and laser photolysis of NP-EGTA resulted in constriction of adjacent blood vessels. Our results indicate that ATP and glutamate are released ectopically by vesicles along axons and mediate neurovascular coupling via glial Ca(2+) signaling.

  18. Rapid structural alterations of the active zone lead to sustained changes in neurotransmitter release.

    PubMed

    Matz, Jacob; Gilyan, Andrew; Kolar, Annette; McCarvill, Terrence; Krueger, Stefan R

    2010-05-11

    The likelihood with which an action potential elicits neurotransmitter release, the release probability (p(r)), is an important component of synaptic strength. Regulatory mechanisms controlling several steps of synaptic vesicle (SV) exocytosis may affect p(r), yet their relative importance in determining p(r) and eliciting temporal changes in neurotransmitter release at individual synapses is largely unknown. We have investigated whether the size of the active zone cytomatrix is a major determinant of p(r) and whether changes in its size lead to corresponding alterations in neurotransmitter release. We have used a fluorescent sensor of SV exocytosis, synaptophysin-pHluorin, to measure p(r) at individual synapses with high accuracy and employed a fluorescently labeled cytomatrix protein, Bassoon, to quantify the amount of active zone cytomatrix present at these synapses. We find that, for synapses made by a visually identified presynaptic neuron, p(r) is indeed strongly correlated with the amount of active zone cytomatrix present at the presynaptic specialization. Intriguingly, active zone cytomatrices are frequently subject to synapse-specific changes in size on a time scale of minutes. These spontaneous alterations in active zone size are associated with corresponding changes in neurotransmitter release. Our results suggest that the size of the active zone cytomatrix has a large influence on the reliability of synaptic transmission. Furthermore, they implicate mechanisms leading to rapid structural alterations at active zones in synapse-specific forms of plasticity.

  19. Waterborne lead affects circadian variations of brain neurotransmitters in fathead minnows

    SciTech Connect

    Spieler, R.E.; Russo, A.C.; Weber, D.N.

    1995-09-01

    Lead is a potent neurotoxin affecting brain levels of a number of vertebrate neurotransmitters. Reports on these effects are, however, not consistent either among or within species. For example, with lead-intoxicated rats there are reports of decreased acetylcholine (ACh) release and decreased ACh brain levels as well as reports of increased levels or no change in levels. Also, with rats there are reports of increased levels, decreased levels, or no change in brain catecholamines, with lead producing similar changes in both norephinephrine (NE) and dopamine (DA) in some cases and differences in response between the two in others. Although most early reports dealt with whole brain levels, reports on neurotransmitter levels in specific brain regions can be equally conflicting. Similar sorts of discrepancies exist among studies with fishes. Much of the variation among studies on lead effects on neurotransmitters is, no doubt, due to differences among the studies in variables such as: species, age, dosage and duration, route of administration. However, lead can apparently affect circadian locomotor rhythms of both rats and fishes. Therefore, another possible cause for the variation among studies is that there is an interaction among dosage, sampling time and endogenous rhythms. A lead-produced phase shift or disruption in endogenous neurotransmitter rhythms could in turn elicit a host of varying results and interpretations depending on the circadian time of sampling. We elected to examine this possibility in the fathead minnow, Pimephales promelas, a freshwater species widely used for toxicity studies. 15 refs., 3 figs.

  20. Effect of Curare on Responses to Different Putative Neurotransmitters in Aplysia.

    DTIC Science & Technology

    1976-06-01

    The effects of curare on responses resulting from ionophoretic application of several putative neurotransmitters onto Aplysia neurons were studied...In Aplysia nervous tissue, curare appears to be a specfic blocking agent for a class of receptor-activated Na and Cl responses.

  1. Mechanism of the association between Na+ binding and conformations at the intracellular gate in neurotransmitter:sodium symporters

    SciTech Connect

    Stolzenberg, Sebastian; Quick, Matthias; Zhao, Chunfeng; Gotfryd, Kamil; Khelashvili, George; Gether, Ulrik; Loland, Claus J.; Javitch, Jonathan A.; Noskov, Sergei; Weinstein, Harel; Shi, Lei

    2015-04-13

    Neurotransmitter:sodium symporters (NSSs) terminate neurotransmission by Na+-dependent reuptake of released neurotransmitters. Previous studies suggested that Na+-binding reconfigures dynamically coupled structural elements in an allosteric interaction network (AIN) responsible for function-related conformational changes, but the intramolecular pathway of this mechanism has remained uncharted. Here we describe a new approach for the modeling and analysis of intramolecular dynamics in the bacterial NSS homolog LeuT. From microsecond-scale molecular dynamics simulations and cognate experimental verifications in both LeuT and human dopamine transporter (hDAT), we apply the novel method to identify the composition and the dynamic properties of their conserved AIN. In LeuT, two different perturbations disrupting Na+ binding and transport (i.e. replacing Na+ with Li+ or the Y268A mutation at the intracellular gate) affect the AIN in strikingly similar ways. In contrast, other mutations that affect the intracellular gate (i.e. R5A and D369A) do not significantly impair Na+ cooperativity and transport. Our analysis shows these perturbations to have much lesser effects on the AIN, underscoring the sensitivity of this novel method to the mechanistic nature of the perturbation. Notably, this set of observations holds as well for hDAT, where the aligned Y335A, R60A, and D436A mutations also produce different impacts on Na+ dependence. Furthermore, the detailed AIN generated from our method is shown to connect Na+ binding with global conformational changes that are critical for the transport mechanism. Lastly, that the AIN between the Na+ binding sites and the intracellular gate in bacterial LeuT resembles that in eukaryotic hDAT highlights the conservation of allosteric pathways underlying NSS function.

  2. Focused crossed Andreev reflection

    NASA Astrophysics Data System (ADS)

    Haugen, H.; Brataas, A.; Waintal, X.; Bauer, G. E. W.

    2011-03-01

    We consider non-local transport mediated by Andreev reflection in a two-dimensional electron gas (2DEG) connected to one superconducting and two normal metal terminals. A robust scheme is presented for observing crossed Andreev reflection (CAR) between the normal metal terminals based on electron focusing by weak perpendicular magnetic fields. At slightly elevated temperatures the CAR signature can be easily distinguished from a background of quantum interference fluctuations. The CAR-induced entanglement between electrons can be switched on and off over large distances by the magnetic field.

  3. Kv3.3 immunoreactivity in the vestibular nuclear complex of the rat with focus on the medial vestibular nucleus: targeting of Kv3.3 neurones by terminals positive for vesicular glutamate transporter 1.

    PubMed

    Brooke, Ruth Elizabeth; Corns, Laura; Edwards, Ian James; Deuchars, Jim

    2010-07-23

    Kv3 voltage-gated K(+) channels are important in shaping neuronal excitability and are abundant in the CNS, with each Kv3 gene exhibiting a unique expression pattern. Mice lacking the gene encoding for the Kv3.3 subunit exhibit motor deficits. Furthermore, mutations in this gene have been linked to the human disease spinocerebellar ataxia 13, associated with cerebellar and extra-cerebellar symptoms such as imbalance and nystagmus. Kv subunit localisation is important in defining their functional roles and thus, we investigated the distribution of Kv3.3-immunoreactivity in the vestibular nuclear complex of rats with particular focus on the medial vestibular nucleus (MVN). Kv3.3-immunoreactivity was widespread in the vestibular nuclei and was detected in somata, dendrites and synaptic terminals. Kv3.3-immunoreactivity was observed in distinct neuronal populations and dual labelling with the neuronal marker NeuN revealed 28.5+/-1.9% of NeuN labelled MVN neurones were Kv3.3-positive. Kv3.3-immunoreactivity co-localised presynaptically with the synaptic vesicle marker SV2, parvalbumin, the vesicular glutamate transporter VGluT2 and the glycine transporter GlyT2. VGluT1 terminals were scarce within the MVN (2.5+/-1.1 per 50 microm(2)) and co-localisation was not observed. However, 85.4+/-9.4% of VGluT1 terminals targeted and enclosed Kv3.3-immunoreactive somata. Presynaptic Kv3.3 co-localisation with the GABAergic marker GAD67 was also not observed. Cytoplasmic GlyT2 labelling was observed in a subset of Kv3.3-positive neurones. Electron microscopy confirmed a pre- and post-synaptic distribution of the Kv3.3 protein. This study provides evidence supporting a role for Kv3.3 subunits in vestibular processing by regulating neuronal excitability pre- and post-synaptically.

  4. Duck cerebellum participates in regulation of food intake via the neurotransmitters serotonin and neuropeptide Y.

    PubMed

    Liu, Hua Z; Li, Xin Y; Tong, Jing J; Qiu, Zheng Y; Zhan, Han C; Sha, Jun N; Peng, Ke M

    2008-10-01

    Two important neurotransmitters, serotonin (5-hydroxytryptamine, 5-HT) and neuropeptide Y (NPY), have been confirmed to be involved in food intake regulation. To clarify whether the cerebellum participates in modulation of food intake through these two neurotransmitters, we investigated the distribution and expression levels of 5-HT and NPY in cerebellum of the duck. Our results showed that 5-HT and NPY were distributed only at the Purkinje cell layer of the duck cerebellum. Moreover, the expression level of 5-HT in fasted (4 h) and tryptophan (100-200 mg/kg)-treated ducks was significantly higher than that in control animals (P<0.01), whereas the expression of NPY was significantly decreased (P<0.01). Therefore, our results indicated that inhibitory regulation of food intake respectively increased and decreased cerebellar 5-HT and NPY in the duck.

  5. Miniaturized and Wireless Optical Neurotransmitter Sensor for Real-Time Monitoring of Dopamine in the Brain

    PubMed Central

    Kim, Min H.; Yoon, Hargsoon; Choi, Sang H.; Zhao, Fei; Kim, Jongsung; Song, Kyo D.; Lee, Uhn

    2016-01-01

    Real-time monitoring of extracellular neurotransmitter concentration offers great benefits for diagnosis and treatment of neurological disorders and diseases. This paper presents the study design and results of a miniaturized and wireless optical neurotransmitter sensor (MWONS) for real-time monitoring of brain dopamine concentration. MWONS is based on fluorescent sensing principles and comprises a microspectrometer unit, a microcontroller for data acquisition, and a Bluetooth wireless network for real-time monitoring. MWONS has a custom-designed application software that controls the operation parameters for excitation light sources, data acquisition, and signal processing. MWONS successfully demonstrated a measurement capability with a limit of detection down to a 100 nanomole dopamine concentration, and high selectivity to ascorbic acid (90:1) and uric acid (36:1). PMID:27834927

  6. Microfluidic in-channel multi-electrode platform for neurotransmitter sensing

    NASA Astrophysics Data System (ADS)

    Kara, A.; Mathault, J.; Reitz, A.; Boisvert, M.; Tessier, F.; Greener, J.; Miled, A.

    2016-03-01

    In this project we present a microfluidic platform with in-channel micro-electrodes for in situ screening of bio/chemical samples through a lab-on-chip system. We used a novel method to incorporate electrochemical sensors array (16x20) connected to a PCB, which opens the way for imaging applications. A 200 μm height microfluidic channel was bonded to electrochemical sensors. The micro-channel contains 3 inlets used to introduce phosphate buffer saline (PBS), ferrocynide and neurotransmitters. The flow rate was controlled through automated micro-pumps. A multiplexer was used to scan electrodes and perform individual cyclic voltammograms by a custom potentiostat. The behavior of the system was linear in terms of variation of current versus concentration. It was used to detect the neurotransmitters serotonin, dopamine and glutamate.

  7. [Detection of neurotransmitter interactions with PET and SPECT by pharmacological challenge paradigms].

    PubMed

    Schlösser, R

    2000-01-01

    Functional brain imaging with positron emission tomography (PET) and single photon emission computerized tomography (SPECT) enables the in vivo study of specific neurochemical processes in the context of normal regulatory mechanisms and pathophysiological alterations of the brain. By combining these methods with pharmacological challenge-paradigms, the study of functional interactions of different neurotransmitter systems is possible. This review will present data from animal and healthy volunteer studies as well as first data from investigations in different patient populations with regard to this research direction. Especially, interactions of different neurotransmitter systems with the dopaminergic and the cholinergic system will be discussed. The database acquired so far confirms existing models of neuronal feedback-circuits, and the first clinical results are consistent with the hypothesis of an increased dopaminergic responsivity in schizophrenic patients. These results open up new perspectives for a further evaluation of treatment response predictors from drug-challenge studies and for the development of new drug treatments for neuropsychiatric disorders.

  8. Analysis of neurotransmitter tissue content of Drosophila melanogaster in different life stages.

    PubMed

    Denno, Madelaine E; Privman, Eve; Venton, B Jill

    2015-01-21

    Drosophila melanogaster is a widely used model organism for studying neurological diseases with similar neurotransmission to mammals. While both larva and adult Drosophila have central nervous systems, not much is known about how neurotransmitter tissue content changes through development. In this study, we quantified tyramine, serotonin, octopamine, and dopamine in larval, pupal, and adult fly brains using capillary electrophoresis coupled to fast-scan cyclic voltammetry. Tyramine and octopamine content varied between life stages, with almost no octopamine being present in the pupa, while tyramine levels in the pupa were very high. Adult females had significantly higher dopamine content than males, but no other neurotransmitters were dependent on sex in the adult. Understanding the tissue content of different life stages will be beneficial for future work comparing the effects of diseases on tissue content throughout development.

  9. New Trends and Perspectives in the Evolution of Neurotransmitters in Microbial, Plant, and Animal Cells.

    PubMed

    Roshchina, Victoria V

    2016-01-01

    The evolutionary perspective on the universal roles of compounds known as neurotransmitters may help in the analysis of relations between all organisms in biocenosis-from microorganisms to plant and animals. This phenomenon, significant for chemosignaling and cellular endocrinology, has been important in human health and the ability to cause disease or immunity, because the "living environment" influences every organism in a biocenosis relationship (microorganism-microorganism, microorganism-plant, microorganism-animal, plant-animal, plant-plant and animal-animal). Non-nervous functions of neurotransmitters (rather "biomediators" on a cellular level) are considered in this review and ample consideration is given to similarities and differences that unite, as well as distinguish, taxonomical kingdoms.

  10. Quantification of Amino Acid Neurotransmitters in Cerebrospinal Fluid of Patients with Neurocysticercosis

    PubMed Central

    Camargo, José Augusto; Bertolucci, Paulo Henrique Ferreira

    2015-01-01

    Background : Neurocysticercosis is a parasitic disease that affects the central nervous system. Its main clinical manifestations are epileptic seizures. The objective of this study was to investigate the correlation between neurotransmitter concentrations in cerebrospinal fluid (CSF) and the different evolutive forms of neurocysticercosis with or without seizures. Methods : Neurotransmitter concentrations (Aspartate, Glutamate, GABA, Glutamine, Glycine, Taurine) were determined in CSF samples from 42 patients with neurocysticercosis divided into patients with the active cystic form (n = 24, 12 with and 12 without seizures) and patients with calcified form (n = 18, 12 with and 6 without seizures), and a control group consisting of 59 healthy subjects. Results : Alterations in amino acid concentration were observed in all patients with neurocysticercosis. Conclusion : We conclude that disturbances in amino acid metabolism accompany the presentation of neurocysticercosis. Replacement of the terms inactive cyst by reactive inactive cyst and calcification by reactive calcification is suggested. PMID:26157521

  11. Probe-pin device for optical neurotransmitter sensing in the brain

    NASA Astrophysics Data System (ADS)

    Kim, Min Hyuck; Song, Kyo D.; Yoon, Hargsoon; Park, Yeonjoon; Choi, Sang H.; Lee, Dae-Sung; Shin, Kyu-Sik; Hwang, Hak-In; Lee, Uhn

    2015-04-01

    Development of an optical neurotransmitter sensing device using nano-plasmonic probes and a micro-spectrometer for real time monitoring of neural signals in the brain is underway. Clinical application of this device technology is to provide autonomous closed-loop feedback control to a deep brain stimulation (DBS) system and enhance the accuracy and efficacy of DBS treatment. By far, we have developed an implantable probe-pin device based on localized field enhancement of surface plasmonic resonance on a nanostructured sensing domain which can amplify neurochemical signals from evoked neural activity in the brain. In this paper, we will introduce the details of design and sensing performance of a proto-typed microspectrometer and nanostructured probing devices for real time measurement of neurotransmitter concentrations.

  12. FMRP regulates neurotransmitter release and synaptic information transmission by modulating action potential duration via BK channels.

    PubMed

    Deng, Pan-Yue; Rotman, Ziv; Blundon, Jay A; Cho, Yongcheol; Cui, Jianmin; Cavalli, Valeria; Zakharenko, Stanislav S; Klyachko, Vitaly A

    2013-02-20

    Loss of FMRP causes fragile X syndrome (FXS), but the physiological functions of FMRP remain highly debatable. Here we show that FMRP regulates neurotransmitter release in CA3 pyramidal neurons by modulating action potential (AP) duration. Loss of FMRP leads to excessive AP broadening during repetitive activity, enhanced presynaptic calcium influx, and elevated neurotransmitter release. The AP broadening defects caused by FMRP loss have a cell-autonomous presynaptic origin and can be acutely rescued in postnatal neurons. These presynaptic actions of FMRP are translation independent and are mediated selectively by BK channels via interaction of FMRP with BK channel's regulatory β4 subunits. Information-theoretical analysis demonstrates that loss of these FMRP functions causes marked dysregulation of synaptic information transmission. FMRP-dependent AP broadening is not limited to the hippocampus, but also occurs in cortical pyramidal neurons. Our results thus suggest major translation-independent presynaptic functions of FMRP that may have important implications for understanding FXS neuropathology.

  13. Carbon nanotube yarn electrodes for enhanced detection of neurotransmitter dynamics in live brain tissue.

    PubMed

    Schmidt, Andreas C; Wang, Xin; Zhu, Yuntian; Sombers, Leslie A

    2013-09-24

    This work demonstrates the potential of nanoscale carbon electrode materials for improved detection of electroactive neurotransmitter dynamics in the brain. Individual multiwalled carbon nanotubes were synthesized via chemical vapor deposition, spun into yarns, and used in the fabrication of disk microelectrodes that were subsequently characterized using scanning electron and atomic force microscopies. The carbon nanotube yarn electrodes were coupled with fast-scan cyclic voltammetry and used to discriminately detect rapid neurotransmitter fluctuations in acute brain slices. The results demonstrate that the distinct structural and electronic properties of the nanotubes result in improved selectivity, sensitivity, and spatial resolution, as well as faster apparent electron transfer kinetics when compared to the conventional carbon-fiber microelectrodes typically used in vivo.

  14. Phosphorylation of Complexin by PKA Regulates Activity-dependent Spontaneous Neurotransmitter Release and Structural Synaptic Plasticity

    PubMed Central

    Cho, Richard W.; Buhl, Lauren K.; Volfson, Dina; Tran, Adrienne; Li, Feng; Akbergenova, Yulia; Littleton, J. Troy

    2016-01-01

    Summary Synaptic plasticity is a fundamental feature of the nervous system that allows adaptation to changing behavioral environments. Most studies of synaptic plasticity have examined the regulated trafficking of postsynaptic glutamate receptors that generates alterations in synaptic transmission. Whether and how changes in the presynaptic release machinery contribute to neuronal plasticity is less clear. The SNARE complex mediates neurotransmitter release in response to presynaptic Ca++ entry. Here we show that the SNARE fusion clamp Complexin undergoes activity-dependent phosphorylation that alters the basic properties of neurotransmission in Drosophila. Retrograde signaling following stimulation activates PKA-dependent phosphorylation of the Complexin C-terminus that selectively and transiently enhances spontaneous release. Enhanced spontaneous release is required for activity-dependent synaptic growth. These data indicate that SNARE-dependent fusion mechanisms can be regulated in an activity-dependent manner and highlight the key role of spontaneous neurotransmitter release as a mediator of functional and structural plasticity. PMID:26590346

  15. Neuron-glia signaling in developing retina mediated by neurotransmitter spillover.

    PubMed

    Rosa, Juliana M; Bos, Rémi; Sack, Georgeann S; Fortuny, Cécile; Agarwal, Amit; Bergles, Dwight E; Flannery, John G; Feller, Marla B

    2015-08-14

    Neuron-glia interactions play a critical role in the maturation of neural circuits; however, little is known about the pathways that mediate their communication in the developing CNS. We investigated neuron-glia signaling in the developing retina, where we demonstrate that retinal waves reliably induce calcium transients in Müller glial cells (MCs). During cholinergic waves, MC calcium transients were blocked by muscarinic acetylcholine receptor antagonists, whereas during glutamatergic waves, MC calcium transients were inhibited by ionotropic glutamate receptor antagonists, indicating that the responsiveness of MCs changes to match the neurotransmitter used to support retinal waves. Using an optical glutamate sensor we show that the decline in MC calcium transients is caused by a reduction in the amount of glutamate reaching MCs. Together, these studies indicate that neurons and MCs exhibit correlated activity during a critical period of retinal maturation that is enabled by neurotransmitter spillover from retinal synapses.

  16. Computational approaches for the study of serotonin and its membrane transporter SERT: implications for drug design in neurological sciences.

    PubMed

    Pratuangdejkul, J; Schneider, B; Launay, J-M; Kellermann, O; Manivet, P

    2008-01-01

    Serotonin (5-hydroxytryptamine, 5-HT), a monoamine neurotransmitter of the central nervous and peripheral systems (CNS), plays a critical role in a wide variety of physiological and behavioral processes. In the serotonergic system, deregulation of the tightly controlled extracellular concentration of 5-HT appears to be at the origin of a host of metabolic and psychiatric disorders. A key step that regulates 5-HT external level is the re-uptake of 5-HT into cells by the 5-HT transporter (SERT), which is besides the target of numerous drugs interacting with the serotonergic system. Therapeutic strategies have mainly focused on the development of compounds that block the activity of SERT, for instance reuptake inhibitors (e.g. tricyclics, "selective" serotonin reuptake inhibitors) and in the past, specific substrate-type releasers (e.g. amphetamine and cocaine derivatives). Today, generation of new drugs targetting SERT with enhanced selectivity and reduced toxicity is one of the most challenging tasks in drug design. In this context, studies aiming at characterizing the physicochemical properties of 5-HT as well as the biological active conformation of SERT are a prerequisite to the design of new leads. However, the absence of a high-resolution 3D-structure for SERT has hampered the design of new transporter inhibitors. Using computational approaches, numerous efforts were made to shed light on the structure of 5-HT and its transporter. In this review, we compared several in silico methods dedicated to the modeling of 5-HT and SERT with an emphasis on i) quantum chemistry for study of 5-HT conformation and ii) ligand-based (QSAR and pharmacophore models) and transporter-based (homology models) approaches for studying SERT molecule. In addition, we discuss some methodological aspects of the computational work in connection with the construction of putative but reliable 3D structural models of SERT that may help to predict the mechanisms of neurotransmitter transport.

  17. SLC Transporters as Therapeutic Targets: Emerging Opportunities

    PubMed Central

    Lin, Lawrence; Yee, Sook Wah; Kim, Richard B.; Giacomini, Kathleen M.

    2015-01-01

    Solute carrier (SLC) transporters — a family of more than 300 membrane-bound proteins that facilitate the transport of a wide array of substrates across biological membranes — have important roles in physiological processes ranging from the cellular uptake of nutrients to the absorption of drugs and other xenobiotics. Several classes of marketed drugs target well-known SLC transporters, such as neurotransmitter transporters, and human genetic studies have provided powerful insight into the roles of more-recently characterized SLC transporters in both rare and common diseases, indicating a wealth of new therapeutic opportunities. This Review summarizes knowledge on the roles of SLC transporters in human disease, describes strategies to target such transporters, and highlights current and investigational drugs that modulate SLC transporters, as well as promising drug targets. PMID:26111766

  18. Aspects of astrocyte energy metabolism, amino acid neurotransmitter homoeostasis and metabolic compartmentation.

    PubMed

    Kreft, Marko; Bak, Lasse K; Waagepetersen, Helle S; Schousboe, Arne

    2012-04-27

    Astrocytes are key players in brain function; they are intimately involved in neuronal signalling processes and their metabolism is tightly coupled to that of neurons. In the present review, we will be concerned with a discussion of aspects of astrocyte metabolism, including energy-generating pathways and amino acid homoeostasis. A discussion of the impact that uptake of neurotransmitter glutamate may have on these pathways is included along with a section on metabolic compartmentation.

  19. Regulation of nonsmall-cell lung cancer stem cell like cells by neurotransmitters and opioid peptides.

    PubMed

    Banerjee, Jheelam; Papu John, Arokya M S; Schuller, Hildegard M

    2015-12-15

    Nonsmall-cell lung cancer (NSCLC) is the leading type of lung cancer and has a poor prognosis. We have shown that chronic stress promoted NSCLC xenografts in mice via stress neurotransmitter-activated cAMP signaling downstream of beta-adrenergic receptors and incidental beta-blocker therapy was reported to improve clinical outcomes in NSCLC patients. These findings suggest that psychological stress promotes NSCLC whereas pharmacologically or psychologically induced decreases in cAMP may inhibit NSCLC. Cancer stem cells are thought to drive the development, progression and resistance to therapy of NSCLC. However, their potential regulation by stress neurotransmitters has not been investigated. In the current study, epinephrine increased the number of cancer stem cell like cells (CSCs) from three NSCLC cell lines in spheroid formation assays while enhancing intracellular cAMP and the stem cell markers sonic hedgehog (SHH), aldehyde dehydrogenase-1 (ALDH-1) and Gli1, effects reversed by GABA or dynorphin B via Gαi -mediated inhibition of cAMP formation. The growth of NSCLC xenografts in a mouse model of stress reduction was significantly reduced as compared with mice maintained under standard conditions. Stress reduction reduced serum levels of corticosterone, norepinephrine and epinephrine while the inhibitory neurotransmitter γ-aminobutyric acid (GABA) and opioid peptides increased. Stress reduction significantly reduced cAMP, VEGF, p-ERK, p-AKT, p-CREB, p-SRc, SHH, ALDH-1 and Gli1 in xenograft tissues whereas cleaved caspase-3 and p53 were induced. We conclude that stress neurotransmitters activate CSCs in NSCLC via multiple cAMP-mediated pathways and that pharmacologically or psychologically induced decreases in cAMP signaling may improve clinical outcomes in NSCLC patients.

  20. The role of peripheral nerve fibers and their neurotransmitters in cartilage and bone physiology and pathophysiology.

    PubMed

    Grässel, Susanne G

    2014-01-01

    The peripheral nervous system is critically involved in bone metabolism, osteogenesis, and bone remodeling. Nerve fibers of sympathetic and sensory origin innervate synovial tissue and subchondral bone of diathrodial joints. They modulate vascularization and matrix differentiation during endochondral ossification in embryonic limb development, indicating a distinct role in skeletal growth and limb regeneration processes. In pathophysiological situations, the innervation pattern of sympathetic and sensory nerve fibers is altered in adult joint tissues and bone. Various resident cell types of the musculoskeletal system express receptors for sensory and sympathetic neurotransmitters. Osteoblasts, osteoclasts, mesenchymal stem cells, synovial fibroblasts, and different types of chondrocytes produce distinct subtypes of adrenoceptors, receptors for vasointestinal peptide, for substance P and calcitonin gene-related peptide. Many of these cells even synthesize neuropeptides such as substance P and calcitonin gene-related peptide and are positive for tyrosine-hydroxylase, the rate-limiting enzyme for biosynthesis of catecholamines. Sensory and sympathetic neurotransmitters modulate osteo-chondrogenic differentiation of mesenchymal progenitor cells during endochondral ossification in limb development. In adults, sensory and sympathetic neurotransmitters are critical for bone regeneration after fracture and are involved in the pathology of inflammatory diseases as rheumatoid arthritis which manifests mainly in joints. Possibly, they might also play a role in pathogenesis of degenerative joint disorders, such as osteoarthritis. All together, accumulating data imply that sensory and sympathetic neurotransmitters have crucial trophic effects which are critical for proper limb formation during embryonic skeletal growth. In adults, they modulate bone regeneration, bone remodeling, and articular cartilage homeostasis in addition to their classic neurological actions.

  1. Aspects of astrocyte energy metabolism, amino acid neurotransmitter homoeostasis and metabolic compartmentation

    PubMed Central

    Kreft, Marko; Bak, Lasse K; Waagepetersen, Helle S; Schousboe, Arne

    2012-01-01

    Astrocytes are key players in brain function; they are intimately involved in neuronal signalling processes and their metabolism is tightly coupled to that of neurons. In the present review, we will be concerned with a discussion of aspects of astrocyte metabolism, including energy-generating pathways and amino acid homoeostasis. A discussion of the impact that uptake of neurotransmitter glutamate may have on these pathways is included along with a section on metabolic compartmentation. PMID:22435484

  2. OATPs, OATs and OCTs: the organic anion and cation transporters of the SLCO and SLC22A gene superfamilies

    PubMed Central

    Roth, Megan; Obaidat, Amanda; Hagenbuch, Bruno

    2012-01-01

    The human organic anion and cation transporters are classified within two SLC superfamilies. Superfamily SLCO (formerly SLC21A) consists of organic anion transporting polypeptides (OATPs), while the organic anion transporters (OATs) and the organic cation transporters (OCTs) are classified in the SLC22A superfamily. Individual members of each superfamily are expressed in essentially every epithelium throughout the body, where they play a significant role in drug absorption, distribution and elimination. Substrates of OATPs are mainly large hydrophobic organic anions, while OATs transport smaller and more hydrophilic organic anions and OCTs transport organic cations. In addition to endogenous substrates, such as steroids, hormones and neurotransmitters, numerous drugs and other xenobiotics are transported by these proteins, including statins, antivirals, antibiotics and anticancer drugs. Expression of OATPs, OATs and OCTs can be regulated at the protein or transcriptional level and appears to vary within each family by both protein and tissue type. All three superfamilies consist of 12 transmembrane domain proteins that have intracellular termini. Although no crystal structures have yet been determined, combinations of homology modelling and mutation experiments have been used to explore the mechanism of substrate recognition and transport. Several polymorphisms identified in members of these superfamilies have been shown to affect pharmacokinetics of their drug substrates, confirming the importance of these drug transporters for efficient pharmacological therapy. This review, unlike other reviews that focus on a single transporter family, briefly summarizes the current knowledge of all the functionally characterized human organic anion and cation drug uptake transporters of the SLCO and the SLC22A superfamilies. LINKED ARTICLES BJP recently published a themed section on Transporters. To view the papers in this section visit http://dx.doi.org/10.1111/bph.2011

  3. The molecular basis of memory. Part 3: tagging with “emotive” neurotransmitters

    PubMed Central

    Marx, Gerard; Gilon, Chaim

    2014-01-01

    Many neurons of all animals that exhibit memory (snails, worms, flies, vertebrae) present arborized shapes with many varicosities and boutons. These neurons, release neurotransmitters and contain ionotropic receptors that produce and sense electrical signals (ephaptic transmission). The extended shapes maximize neural contact with the surrounding neutrix [defined as: neural extracellular matrix (nECM) + diffusible (neurometals and neurotransmitters)] as well as with other neurons. We propose a tripartite mechanism of animal memory based on the dynamic interactions of splayed neurons with the “neutrix.” Their interactions form cognitive units of information (cuinfo), metal-centered complexes within the nECM around the neuron. Emotive content is provided by NTs, which embody molecular links between physiologic (body) responses and psychic feelings. We propose that neurotransmitters form mixed complexes with cuinfo used for tagging emotive memory. Thus, NTs provide encoding option not available to a Turing, binary-based, device. The neurons employ combinatorially diverse options, with >10 NMs and >90 NTs for encoding (“flavoring”) cuinfo with emotive tags. The neural network efficiently encodes, decodes and consolidates related (entangled) sets of cuinfo into a coherent pattern, the basis for emotionally imbued memory, critical for determining a behavioral choice aimed at survival. The tripartite mechanism with tagging of NTs permits of a causal connection between physiology and psychology. PMID:24778616

  4. Altered levels of brain neurotransmitter from new born rabbits with intrauterine restriction.

    PubMed

    Hernández-Andrade, E; Cortés-Camberos, A J; Díaz, N F; Flores-Herrera, H; García-López, G; González-Jiménez, M; Santamaría, A; Molina-Hernández, A

    2015-01-01

    Fetal intrauterine growth restriction generates chronic hypoxia due to placental insufficiency. Despite the hemodynamic process of blood flow, redistributions are taking place in key organs such as the fetal brain during intrauterine growth restriction, in order to maintain oxygen and nutrients supply. The risk of short- and long-term neurological effects are still present in hypoxic offspring. Most studies previously reported the effect of hypoxia on the levels of a single neurotransmitter, making it difficult to have a better understanding of the relationship among neurotransmitter levels and the defects reported in products that suffer intrauterine growth restriction, such as motor development, coordination and execution of movement, and the learning-memory process. The aim of this study was to evaluate the levels of gamma-aminobutyric acid, glutamate, dopamine and serotonin in three structures of the brain related to the above-mentioned function such as the cerebral cortex, the striatum, and the hippocampus in the chronic hypoxic newborn rabbit model. Our results showed a significant increase in glutamate and dopamine levels in all studied brain structures and a significant decrease in gamma-aminobutyric acid levels but only in the striatum, suggesting that the imbalance on the levels of several neurotransmitters could be involved in new born brain damage due to perinatal hypoxia.

  5. Sex and intrauterine growth restriction modify brain neurotransmitters profile of newborn piglets.

    PubMed

    Vázquez-Gómez, M; Valent, D; García-Contreras, C; Arroyo, L; Óvilo, C; Isabel, B; Bassols, A; González-Bulnes, A

    2016-12-01

    The current study aimed to determine, using a swine model of intrauterine growth restriction (IUGR), whether short- and long-term neurological deficiencies and interactive dysfunctions of Low Birth-Weight (LBW) offspring might be related to altered pattern of neurotransmitters. Hence, we compared the quantities of different neurotransmitters (catecholamines and indoleamines), which were determined by HPLC, at brain structures related to the limbic system (hippocampus and amygdala) in 14 LBW and 10 Normal Body-Weight (NBW) newborn piglets. The results showed, firstly, significant effects of sex on the NBW newborns, with females having higher dopamine (DA) concentrations than males. The IUGR processes affected DA metabolism, with LBW piglets having lower concentrations of noradrenaline at the hippocampus and higher concentrations of the DA metabolites, homovanillic acid (HVA), at both the hippocampus and the amygdala than NBW neonates. The effects of IUGR were modulated by sex; there were no significant differences between LBW and NBW females, but LBW males had higher HVA concentration at the amygdala and higher concentration of 5-hydroxyindoleacetic acid, the serotonin metabolite, at the hippocampus than NBW males. In conclusion, the present study shows that IUGR is mainly related to changes, modulated by sex, in the concentrations of catecholamine neurotransmitters, which are related to adaptation to physical activity and to essential cognitive functions such as learning, memory, reward-motivated behavior and stress.

  6. Differential stimulation of the retina with subretinally injected exogenous neurotransmitter: A biomimetic alternative to electrical stimulation

    PubMed Central

    Rountree, Corey M.; Inayat, Samsoon; Troy, John B.; Saggere, Laxman

    2016-01-01

    Subretinal stimulation of the retina with neurotransmitters, the normal means of conveying visual information, is a potentially better alternative to electrical stimulation widely used in current retinal prostheses for treating blindness from photoreceptor degenerative diseases. Yet, no subretinal electrical or chemical stimulation study has stimulated the OFF and ON pathways differentially through inner retinal activation. Here, we demonstrate the feasibility of differentially stimulating retinal ganglion cells (RGCs) through the inner nuclear layer of the retina with glutamate, a primary neurotransmitter chemical, in a biomimetic way. We show that controlled pulsatile delivery of glutamate into the subsurface of explanted wild-type rat retinas elicits highly localized simultaneous inhibitory and excitatory spike rate responses in OFF and ON RGCs. We also present the spatiotemporal characteristics of RGC responses to subretinally injected glutamate and the therapeutic stimulation parameters. Our findings could pave the way for future development of a neurotransmitter-based subretinal prosthesis offering more naturalistic vision and better visual acuity than electrical prostheses. PMID:27929043

  7. Modulation of monoamine neurotransmitters in fighting fish Betta splendens exposed to waterborne phytoestrogens.

    PubMed

    Clotfelter, Ethan D; McNitt, Meredith M; Carpenter, Russ E; Summers, Cliff H

    2010-12-01

    Endogenous estrogens are known to affect the activity of monoamine neurotransmitters in vertebrate animals, but the effects of exogenous estrogens on neurotransmitters are relatively poorly understood. We exposed sexually mature male fighting fish Betta splendens to environmentally relevant and pharmacological doses of three phytoestrogens that are potential endocrine disruptors in wild fish populations: genistein, equol, and β-sitosterol. We also exposed fish to two doses of the endogenous estrogen 17β-estradiol, which we selected as a positive control because phytoestrogens are putative estrogen mimics. Our results were variable, but the effects were generally modest. Genistein increased dopamine levels in the forebrains of B. splendens at both environmentally relevant and pharmacological doses. The environmentally relevant dose of equol increased dopamine levels in B. splendens forebrains, and the pharmacological dose decreased norepinephrine (forebrain), dopamine (hindbrain), and serotonin (forebrain) levels. The environmentally relevant dose of β-sitosterol decreased norepinephrine and dopamine in the forebrain and hindbrain, respectively. Our results suggest that sources of environmental phytoestrogens, such as runoff or effluent from agricultural fields, wood pulp mills, and sewage treatment plants, have the potential to modulate neurotransmitter activity in free-living fishes in a way that could interfere with normal behavioral processes.

  8. Simultaneous analysis of multiple neurotransmitters by hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry.

    PubMed

    Tufi, Sara; Lamoree, Marja; de Boer, Jacob; Leonards, Pim

    2015-05-22

    Neurotransmitters are endogenous metabolites that allow the signal transmission across neuronal synapses. Their biological role is crucial for many physiological functions and their levels can be changed by several diseases. Because of their high polarity, hydrophilic interaction liquid chromatography (HILIC) is a promising tool for neurotransmitter analysis. Due to the large number of HILIC stationary phases available, an evaluation of the column performances and retention behaviors has been performed on five different commercial HILIC packing materials (silica, amino, amide and two zwitterionic stationary phases). Several parameters like the linear correlation between retention and the distribution coefficient (logD), the separation factor k and the column resolution Rs have been investigated and the column performances have been visualized with a heat map and hierarchical clustering analysis. An optimized and validated HILIC-MS/MS method based on the ZIC-cHILIC column is proposed for the simultaneous detection and quantification of twenty compounds consisting of neurotransmitters, precursors and metabolites: 3-methoxytyramine (3-MT), 5-hydroxyindoleacetic acid (5-HIAA), 5-hydroxy-L-tripthophan, acetylcholine, choline, L-3,4-dihydroxyphenylalanine (L-DOPA), dopamine, epinephrine, γ-aminobutyric acid (GABA), glutamate, glutamine, histamine, histidine, L-tryptophan, L-tyrosine, norepinephrine, normetanephrine, phenylalanine, serotonin and tyramine. The method was applied to neuronal metabolite profiling of the central nervous system of the freshwater snail Lymnaea stagnalis. This method is suitable to explore neuronal metabolism and its alteration in different biological matrices.

  9. Individual differences in visual motion perception and neurotransmitter concentrations in the human brain.

    PubMed

    Takeuchi, Tatsuto; Yoshimoto, Sanae; Shimada, Yasuhiro; Kochiyama, Takanori; Kondo, Hirohito M

    2017-02-19

    Recent studies have shown that interindividual variability can be a rich source of information regarding the mechanism of human visual perception. In this study, we examined the mechanisms underlying interindividual variability in the perception of visual motion, one of the fundamental components of visual scene analysis, by measuring neurotransmitter concentrations using magnetic resonance spectroscopy. First, by psychophysically examining two types of motion phenomena-motion assimilation and contrast-we found that, following the presentation of the same stimulus, some participants perceived motion assimilation, while others perceived motion contrast. Furthermore, we found that the concentration of the excitatory neurotransmitter glutamate-glutamine (Glx) in the dorsolateral prefrontal cortex (Brodmann area 46) was positively correlated with the participant's tendency to motion assimilation over motion contrast; however, this effect was not observed in the visual areas. The concentration of the inhibitory neurotransmitter γ-aminobutyric acid had only a weak effect compared with that of Glx. We conclude that excitatory process in the suprasensory area is important for an individual's tendency to determine antagonistically perceived visual motion phenomena.This article is part of the themed issue 'Auditory and visual scene analysis'.

  10. Protein-protein interactions and protein modules in the control of neurotransmitter release.

    PubMed Central

    Benfenati, F; Onofri, F; Giovedí, S

    1999-01-01

    Information transfer among neurons is operated by neurotransmitters stored in synaptic vesicles and released to the extracellular space by an efficient process of regulated exocytosis. Synaptic vesicles are organized into two distinct functional pools, a large reserve pool in which vesicles are restrained by the actin-based cytoskeleton, and a quantitatively smaller releasable pool in which vesicles approach the presynaptic membrane and eventually fuse with it on stimulation. Both synaptic vesicle trafficking and neurotransmitter release depend on a precise sequence of events that include release from the reserve pool, targeting to the active zone, docking, priming, fusion and endocytotic retrieval of synaptic vesicles. These steps are mediated by a series of specific interactions among cytoskeletal, synaptic vesicle, presynaptic membrane and cytosolic proteins that, by acting in concert, promote the spatial and temporal regulation of the exocytotic machinery. The majority of these interactions are mediated by specific protein modules and domains that are found in many proteins and are involved in numerous intracellular processes. In this paper, the possible physiological role of these multiple protein-protein interactions is analysed, with ensuing updating and clarification of the present molecular model of the process of neurotransmitter release. PMID:10212473

  11. Sympathetic Neurotransmitters Modulate Osteoclastogenesis and Osteoclast Activity in the Context of Collagen-Induced Arthritis

    PubMed Central

    Muschter, Dominique; Schäfer, Nicole; Stangl, Hubert; Straub, Rainer H.; Grässel, Susanne

    2015-01-01

    Excessive synovial osteoclastogenesis is a hallmark of rheumatoid arthritis (RA). Concomitantly, local synovial changes comprise neuronal components of the peripheral sympathetic nervous system. Here, we wanted to analyze if collagen-induced arthritis (CIA) alters bone marrow-derived macrophage (BMM) osteoclastogenesis and osteoclast activity, and how sympathetic neurotransmitters participate in this process. Therefore, BMMs from Dark Agouti rats at different CIA stages were differentiated into osteoclasts in vitro and osteoclast number, cathepsin K activity, matrix resorption and apoptosis were analyzed in the presence of acetylcholine (ACh), noradrenaline (NA) vasoactive intestinal peptide (VIP) and assay-dependent, adenylyl cyclase activator NKH477. We observed modulation of neurotransmitter receptor mRNA expression in CIA osteoclasts without affecting protein level. CIA stage-dependently altered marker gene expression associated with osteoclast differentiation and activity without affecting osteoclast number or activity. Neurotransmitter stimulation modulated osteoclast differentiation, apoptosis and activity. VIP, NA and adenylyl cyclase activator NKH477 inhibited cathepsin K activity and osteoclastogenesis (NKH477, 10-6M NA) whereas ACh mostly acted pro-osteoclastogenic. We conclude that CIA alone does not affect metabolism of in vitro generated osteoclasts whereas stimulation with NA, VIP plus specific activation of adenylyl cyclase induced anti-resorptive effects probably mediated via cAMP signaling. Contrary, we suggest pro-osteoclastogenic and pro-resorptive properties of ACh mediated via muscarinic receptors. PMID:26431344

  12. Organic anion transporter (Slc22a) family members as mediators of toxicity

    SciTech Connect

    Sweet, Douglas H. . E-mail: sweetd@musc.edu

    2005-05-01

    Exposure of the body to toxic organic anions is unavoidable and occurs from both intentional and unintentional sources. Many hormones, neurotransmitters, and waste products of cellular metabolism, or their metabolites, are organic anions. The same is true for a wide variety of medications, herbicides, pesticides, plant and animal toxins, and industrial chemicals and solvents. Rapid and efficient elimination of these substances is often the body's best defense for limiting both systemic exposure and the duration of their pharmacological or toxicological effects. For organic anions, active transepithelial transport across the renal proximal tubule followed by elimination via the urine is a major pathway in this detoxification process. Accordingly, a large number of organic anion transport proteins belonging to several different gene families have been identified and found to be expressed in the proximal nephron. The function of these transporters, in combination with the high volume of renal blood flow, predisposes the kidney to increased toxic susceptibility. Understanding how the kidney mediates the transport of organic anions is integral to achieving desired therapeutic outcomes in response to drug interactions and chemical exposures, to understanding the progression of some disease states, and to predicting the influence of genetic variation upon these processes. This review will focus on the organic anion transporter (OAT) family and discuss the known members, their mechanisms of action, subcellular localization, and current evidence implicating their function as a determinant of the toxicity of certain endogenous and xenobiotic agents.

  13. Individual synaptic vesicles from the electroplaque of Torpedo californica, a classic cholinergic synapse, also contain transporters for glutamate and ATP

    PubMed Central

    Li, Huinan; Harlow, Mark L.

    2014-01-01

    Abstract The type of neurotransmitter secreted by a neuron is a product of the vesicular transporters present on its synaptic vesicle membranes and the available transmitters in the local cytosolic environment where the synaptic vesicles reside. Synaptic vesicles isolated from electroplaques of the marine ray, Torpedo californica, have served as model vesicles for cholinergic neurotransmission. Many lines of evidence support the idea that in addition to acetylcholine, additional neurotransmitters and/or neuromodulators are also released from cholinergic synapses. We identified the types of vesicular neurotransmitter transporters present at the electroplaque using immunoblot and immunofluoresence techniques with antibodies against the vesicle acetylcholine transporter (VAChT), the vesicular glutamate transporters (VGLUT1, 2, and 3), and the vesicular nucleotide transporter (VNUT). We found that VAChT, VNUT, VGLUT 1 and 2, but not 3 were present by immunoblot, and confirmed that the antibodies were specific to proteins of the axons and terminals of the electroplaque. We used a single‐vesicle imaging technique to determine whether these neurotransmitter transporters were present on the same or different populations of synaptic vesicles. We found that greater than 85% of vesicles that labeled for VAChT colabeled with VGLUT1 or VGLUT2, and approximately 70% colabeled with VNUT. Based upon confidence intervals, at least 52% of cholinergic vesicles isolated are likely to contain all four transporters. The presence of multiple types of neurotransmitter transporters – and potentially neurotransmitters – in individual synaptic vesicles raises fundamental questions about the role of cotransmitter release and neurotransmitter synergy at cholinergic synapses. PMID:24744885

  14. Environment- and activity-dependent dopamine neurotransmitter plasticity in the adult substantia nigra.

    PubMed

    Aumann, Tim D

    2016-04-01

    The ability of neurons to change the amount or type of neurotransmitter they use, or 'neurotransmitter plasticity', is an emerging new form of adult brain plasticity. For example, it has recently been shown that neurons in the adult rat hypothalamus up- or down-regulate dopamine (DA) neurotransmission in response to the amount of light the animal receives (photoperiod), and that this in turn affects anxiety- and depressive-like behaviors (Dulcis et al., 2013). In this Chapter I consolidate recent evidence from my laboratory suggesting neurons in the adult mouse substantia nigra pars compacta (SNc) also undergo DA neurotransmitter plasticity in response to persistent changes in their electrical activity, including that driven by the mouse's environment or behavior. Specifically, we have shown that the amounts of tyrosine hydroxylase (TH, the rate-limiting enzyme in DA synthesis) gene promoter activity, TH mRNA and TH protein in SNc neurons increases or decreases after ∼20h of altered electrical activity. Also, infusion of ion-channel agonists or antagonists into the midbrain for 2 weeks results in ∼10% (∼500 neurons) more or fewer TH immunoreactive (TH+) SNc neurons, with no change in the total number of SNc neurons (TH+ and TH-). Targeting ion-channels mediating cell-autonomous pacemaker activity in, or synaptic input and afferent pathways to, SNc neurons are equally effective in this regard. In addition, exposing mice to different environments (sex pairing or environment enrichment) for 1-2 weeks induces ∼10% more or fewer TH+ SNc (and ventral tegmental area or VTA) neurons and this is abolished by concurrent blockade of synaptic transmission in midbrain. Although further research is required to establish SNc (and VTA) DA neurotransmitter plasticity, and to determine whether it alters brain function and behavior, it is an exciting prospect because: (1) It may play important roles in movement, motor learning, reward, motivation, memory and cognition; and (2

  15. Pharmacology of Glutamate Transport in the CNS: Substrates and Inhibitors of Excitatory Amino Acid Transporters (EAATs) and the Glutamate/Cystine Exchanger System x c -

    NASA Astrophysics Data System (ADS)

    Bridges, Richard J.; Patel, Sarjubhai A.

    As the primary excitatory neurotransmitter in the mammalian CNS, l-glutamate participates not only in standard fast synaptic communication, but also contributes to higher order signal processing, as well as neuropathology. Given this variety of functional roles, interest has been growing as to how the extracellular concentrations of l-glutamate surrounding neurons are regulated by cellular transporter proteins. This review focuses on two prominent systems, each of which appears capable of influencing both the signaling and pathological actions of l-glutamate within the CNS: the sodium-dependent excitatory amino acid transporters (EAATs) and the glutamate/cystine exchanger, system x c - (Sx c -). While the family of EAAT subtypes limit access to glutamate receptors by rapidly and efficiently sequestering l-glutamate in neurons and glia, Sxc - provides a route for the export of glutamate from cells into the extracellular environment. The primary intent of this work is to provide an overview of the inhibitors and substrates that have been developed to delineate the pharmacological specificity of these transport systems, as well as be exploited as probes with which to selectively investigate function. Particular attention is paid to the development of small molecule templates that mimic the structural properties of the endogenous substrates, l-glutamate, l-aspartate and l-cystine and how strategic control of functional group position and/or the introduction of lipophilic R-groups can impact multiple aspects of the transport process, including: subtype selectivity, inhibitory potency, and substrate activity.

  16. The Role of TM5 in Na2 Release and the Conformational Transition of Neurotransmitter:Sodium Symporters toward the Inward-Open State.

    PubMed

    Stolzenberg, Sebastian; Li, Zheng; Quick, Matthias; Malinauskaite, Lina; Nissen, Poul; Weinstein, Harel; Javitch, Jonathan A; Shi, Lei

    2017-03-20

    Neurotransmitter:sodium symporters (NSS) terminate neurotransmission by the reuptake of released neurotransmitters. This active accumulation of substrate against its concentration gradient is driven by the transmembrane Na+ gradient and requires that the transporter traverses several conformational states. LeuT, a prokaryotic NSS homolog, has been crystallized in outward-open, outward-occluded and inward-open states. Two crystal structures of another prokaryotic NSS homolog, the multi-hydrophobic amino acid transporter (MhsT) from Bacillus halodurans have been resolved in novel inward-occluded states, with the extracellular vestibule closed and the intracellular portion of TM5 (TM5i) in either an unwound or a helical conformation. We have investigated the potential involvement of TM5i in binding and unbinding of Na2, i.e. the Na(+) bound in the Na2 site, by carrying out comparative molecular dynamics simulations of the models derived from the two MhsT structures. We find that the helical TM5i conformation is associated with a higher propensity for Na2 release, which leads to the repositioning of the N terminus (NT) and transition to an inward-open state. By using comparative interaction network analysis, we also identify allosteric pathways connecting TM5i and the Na2 binding site to the extracellular and intracellular regions. Based on our combined computational and mutagenesis studies of MhsT and LeuT, we propose that TM5i plays a key role in Na2 binding and release associated with the conformational transition toward the inward-open state, a role that is likely to be shared across the NSS family.

  17. An Update of the Classical and Novel Methods Used for Measuring Fast Neurotransmitters During Normal and Brain Altered Function

    PubMed Central

    Cifuentes Castro, Victor Hugo; López Valenzuela, Carmen Lucía; Salazar Sánchez, Juan Carlos; Peña, Kenia Pardo; López Pérez, Silvia J.; Ibarra, Jorge Ortega; Villagrán, Alberto Morales

    2014-01-01

    To understand better the cerebral functions, several methods have been developed to study the brain activity, they could be related with morphological, electrophysiological, molecular and neurochemical techniques. Monitoring neurotransmitter concentration is a key role to know better how the brain works during normal or pathological conditions, as well as for studying the changes in neurotransmitter concentration with the use of several drugs that could affect or reestablish the normal brain activity. Immediate response of the brain to environmental conditions is related with the release of the fast acting neurotransmission by glutamate (Glu), γ-aminobutyric acid (GABA) and acetylcholine (ACh) through the opening of ligand-operated ion channels. Neurotransmitter release is mainly determined by the classical microdialysis technique, this is generally coupled to high performance liquid chromatography (HPLC). Detection of neurotransmitters can be done by fluorescence, optical density, electrochemistry or other detection systems more sophisticated. Although the microdialysis method is the golden technique to monitor the brain neurotransmitters, it has a poor temporal resolution. Recently, with the use of biosensor the drawback of temporal resolution has been improved considerably, however other inconveniences have merged, such as stability, reproducibility and the lack of reliable biosensors mainly for GABA. The aim of this review is to show the important advances in the different ways to measure neurotransmitter concentrations; both with the use of classic techniques as well as with the novel methods and alternant approaches to improve the temporal resolution. PMID:25977677

  18. Coupled ion Binding and Structural Transitions Along the Transport Cycle of Glutamate Transporters

    SciTech Connect

    Verdon, Gregory; Oh, SeCheol; Serio, Ryan N.; Boudker, Olga

    2014-05-19

    Membrane transporters that clear the neurotransmitter glutamate from synapses are driven by symport of sodium ions and counter-transport of a potassium ion. Previous crystal structures of a homologous archaeal sodium and aspartate symporter showed that a dedicated transport domain carries the substrate and ions across the membrane. We report new crystal structures of this homologue in ligand-free and ions-only bound outward- and inward-facing conformations. We then show that after ligand release, the apo transport domain adopts a compact and occluded conformation that can traverse the membrane, completing the transport cycle. Sodium binding primes the transport domain to accept its substrate and triggers extracellular gate opening, which prevents inward domain translocation until substrate binding takes place. Moreover, we describe a new cation-binding site ideally suited to bind a counter-transported ion. We suggest that potassium binding at this site stabilizes the translocation-competent conformation of the unloaded transport domain in mammalian homologues.

  19. Cloning of the cocaine-sensitive bovine dopamine transporter

    SciTech Connect

    Usdin, T.B.; Chen, C.; Brownstein, M.J.; Hoffman, B.J. ); Mezey, E. )

    1991-12-15

    A cDNA encoding the dopamine transporter from bovine brain substantia nigra was identified on the basis of its structural homology to other, recently cloned, neurotransmitter transporters. The sequence of the 693-amino acid protein is quite similar to those of the rat {gamma}-aminobutyric acid, human norepinephrine, and rat serotonin transporters. Dopamine transporter mRNA was detected by in situ hybridization in the substantia nigra but not in the locus coeruleus, raphe, caudate, or other brain areas. ({sup 3}H)Dopamine accumulation in tissue culture cells transfected with the cDNA was inhibited by amphetamine, cocaine, and specific inhibitors of dopamine transports, including GBR12909.

  20. Selective amino acid substitutions convert the creatine transporter to a gamma-aminobutyric acid transporter.

    PubMed

    Dodd, Joanna R; Christie, David L

    2007-05-25

    The creatine transporter (CRT) is a member of a large family of sodium-dependent neurotransmitter and amino acid transporters. The CRT is closely related to the gamma-aminobutyric acid (GABA) transporter, GAT-1, yet GABA is not an effective substrate for the CRT. The high resolution structure of a prokaryotic homologue, LeuT has revealed precise details of the substrate binding site for leucine (Yamashita, A., Singh, S. K., Kawate, T., Jin, Y., and Gouaux, E. (2005) Nature 437, 215-223). We have now designed mutations based on sequence comparisons of the CRT with GABA transporters and the LeuT structural template in an attempt to alter the substrate specificity of the CRT. Combinations of two or three amino acid substitutions at four selected positions resulted in the loss of creatine transport activity and gain of a specific GABA transport function. GABA transport by the "gain of function" mutants was sensitive to nipecotic acid, a competitive inhibitor of GABA transporters. Our results show LeuT to be a good structural model to identify amino acid residues involved in the substrate and inhibitor selectivity of eukaryotic sodium-dependent neurotransmitter and amino acid transporters. However, modification of the binding site alone appears to be insufficient for efficient substrate translocation. Additional residues must mediate the conformational changes required for the diffusion of substrate from the binding site to the cytoplasm.

  1. High dose sapropterin dihydrochloride therapy improves monoamine neurotransmitter turnover in murine phenylketonuria (PKU).

    PubMed

    Winn, Shelley R; Scherer, Tanja; Thöny, Beat; Harding, Cary O

    2016-01-01

    Central nervous system (CNS) deficiencies of the monoamine neurotransmitters, dopamine and serotonin, have been implicated in the pathophysiology of neuropsychiatric dysfunction in phenylketonuria (PKU). Increased brain phenylalanine concentration likely competitively inhibits the activities of tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH), the rate limiting steps in dopamine and serotonin synthesis respectively. Tetrahydrobiopterin (BH4) is a required cofactor for TH and TPH activity. Our hypothesis was that treatment of hyperphenylalaninemic Pah(enu2/enu2) mice, a model of human PKU, with sapropterin dihydrochloride, a synthetic form of BH4, would stimulate TH and TPH activities leading to improved dopamine and serotonin synthesis despite persistently elevated brain phenylalanine. Sapropterin (20, 40, or 100mg/kg body weight in 1% ascorbic acid) was administered daily for 4 days by oral gavage to Pah(enu2/enu2) mice followed by measurement of brain biopterin, phenylalanine, tyrosine, tryptophan and monoamine neurotransmitter content. A significant increase in brain biopterin content was detected only in mice that had received the highest sapropterin dose, 100mg/kg. Blood and brain phenylalanine concentrations were unchanged by sapropterin therapy. Sapropterin therapy also did not alter the absolute amounts of dopamine and serotonin in brain but was associated with increased homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), dopamine and serotonin metabolites respectively, in both wild type and Pah(enu2/enu2) mice. Oral sapropterin therapy likely does not directly affect central nervous system monoamine synthesis in either wild type or hyperphenylalaninemic mice but may stimulate synaptic neurotransmitter release and subsequent metabolism.

  2. Chemical stimulation of rat retinal neurons: feasibility of an epiretinal neurotransmitter-based prosthesis

    NASA Astrophysics Data System (ADS)

    Inayat, Samsoon; Rountree, Corey M.; Troy, John B.; Saggere, Laxman

    2015-02-01

    Objective. No cure currently exists for photoreceptor degenerative diseases, which cause partial or total blindness in millions of people worldwide. Electrical retinal prostheses have been developed by several groups with the goal of restoring vision lost to these diseases, but electrical stimulation has limitations. It excites both somas and axons, activating retinal pathways nonphysiologically, and limits spatial resolution because of current spread. Chemical stimulation of retinal ganglion cells (RGCs) using the neurotransmitter glutamate has been suggested as an alternative to electrical stimulation with some significant advantages. However, sufficient scientific data to support developing a chemical-based retinal prosthesis is lacking. The goal of this study was to investigate the feasibility of a neurotransmitter-based retinal prosthesis and determine therapeutic stimulation parameters. Approach. We injected controlled amounts of glutamate into rat retinas from the epiretinal side ex vivo via micropipettes using a pressure injection system and recorded RGC responses with a multielectrode array. Responsive units were identified using a spike rate threshold of 3 Hz. Main results. We recorded both somal and axonal units and demonstrated successful glutamatergic stimulation across different RGC subtypes. Analyses show that exogenous glutamate acts on RGC synapses similar to endogenous glutamate and, unlike electrical prostheses, stimulates only RGC somata. The spatial spread of glutamate stimulation was ˜ 290 μm from the injection site, comparable to current electrical prostheses. Further, the glutamate injections produced spatially differential responses in OFF, ON, and ON-OFF RGC subtypes, suggesting that differential stimulation of the OFF and ON systems may be possible. A temporal resolution of 3.2 Hz was obtained, which is a rate suitable for spatial vision. Significance. We provide strong support for the feasibility of an epiretinal neurotransmitter

  3. Cofactor-dependent conformational heterogeneity of GAD65 and its role in autoimmunity and neurotransmitter homeostasis

    PubMed Central

    Kass, Itamar; Hoke, David E.; Costa, Mauricio G. S.; Reboul, Cyril F.; Porebski, Benjamin T.; Cowieson, Nathan P.; Leh, Hervé; Pennacchietti, Eugenia; McCoey, Julia; Kleifeld, Oded; Borri Voltattorni, Carla; Langley, David; Roome, Brendan; Mackay, Ian R.; Christ, Daniel; Perahia, David; Buckle, Malcolm; Paiardini, Alessandro; De Biase, Daniela; Buckle, Ashley M.

    2014-01-01

    The human neuroendocrine enzyme glutamate decarboxylase (GAD) catalyses the synthesis of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) using pyridoxal 5′-phosphate as a cofactor. GAD exists as two isoforms named according to their respective molecular weights: GAD65 and GAD67. Although cytosolic GAD67 is typically saturated with the cofactor (holoGAD67) and constitutively active to produce basal levels of GABA, the membrane-associated GAD65 exists mainly as the inactive apo form. GAD65, but not GAD67, is a prevalent autoantigen, with autoantibodies to GAD65 being detected at high frequency in patients with autoimmune (type 1) diabetes and certain other autoimmune disorders. The significance of GAD65 autoinactivation into the apo form for regulation of neurotransmitter levels and autoantibody reactivity is not understood. We have used computational and experimental approaches to decipher the nature of the holo → apo conversion in GAD65 and thus, its mechanism of autoinactivation. Molecular dynamics simulations of GAD65 reveal coupling between the C-terminal domain, catalytic loop, and pyridoxal 5′-phosphate–binding domain that drives structural rearrangement, dimer opening, and autoinactivation, consistent with limited proteolysis fragmentation patterns. Together with small-angle X-ray scattering and fluorescence spectroscopy data, our findings are consistent with apoGAD65 existing as an ensemble of conformations. Antibody-binding kinetics suggest a mechanism of mutually induced conformational changes, implicating the flexibility of apoGAD65 in its autoantigenicity. Although conformational diversity may provide a mechanism for cofactor-controlled regulation of neurotransmitter biosynthesis, it may also come at a cost of insufficient development of immune self-tolerance that favors the production of GAD65 autoantibodies. PMID:24927554

  4. Cofactor-dependent conformational heterogeneity of GAD65 and its role in autoimmunity and neurotransmitter homeostasis.

    PubMed

    Kass, Itamar; Hoke, David E; Costa, Mauricio G S; Reboul, Cyril F; Porebski, Benjamin T; Cowieson, Nathan P; Leh, Hervé; Pennacchietti, Eugenia; McCoey, Julia; Kleifeld, Oded; Borri Voltattorni, Carla; Langley, David; Roome, Brendan; Mackay, Ian R; Christ, Daniel; Perahia, David; Buckle, Malcolm; Paiardini, Alessandro; De Biase, Daniela; Buckle, Ashley M

    2014-06-24

    The human neuroendocrine enzyme glutamate decarboxylase (GAD) catalyses the synthesis of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) using pyridoxal 5'-phosphate as a cofactor. GAD exists as two isoforms named according to their respective molecular weights: GAD65 and GAD67. Although cytosolic GAD67 is typically saturated with the cofactor (holoGAD67) and constitutively active to produce basal levels of GABA, the membrane-associated GAD65 exists mainly as the inactive apo form. GAD65, but not GAD67, is a prevalent autoantigen, with autoantibodies to GAD65 being detected at high frequency in patients with autoimmune (type 1) diabetes and certain other autoimmune disorders. The significance of GAD65 autoinactivation into the apo form for regulation of neurotransmitter levels and autoantibody reactivity is not understood. We have used computational and experimental approaches to decipher the nature of the holo → apo conversion in GAD65 and thus, its mechanism of autoinactivation. Molecular dynamics simulations of GAD65 reveal coupling between the C-terminal domain, catalytic loop, and pyridoxal 5'-phosphate-binding domain that drives structural rearrangement, dimer opening, and autoinactivation, consistent with limited proteolysis fragmentation patterns. Together with small-angle X-ray scattering and fluorescence spectroscopy data, our findings are consistent with apoGAD65 existing as an ensemble of conformations. Antibody-binding kinetics suggest a mechanism of mutually induced conformational changes, implicating the flexibility of apoGAD65 in its autoantigenicity. Although conformational diversity may provide a mechanism for cofactor-controlled regulation of neurotransmitter biosynthesis, it may also come at a cost of insufficient development of immune self-tolerance that favors the production of GAD65 autoantibodies.

  5. Effects of colistin on amino acid neurotransmitters and blood-brain barrier in the mouse brain.

    PubMed

    Wang, Jian; Yi, Meishuang; Chen, Xueping; Muhammad, Ishfaq; Liu, Fangping; Li, Rui; Li, Jian; Li, Jichang

    2016-01-01

    Neurotoxicity is one of the major potential side effects of colistin therapy. However, the mechanistic aspects of colistin-induced neurotoxicity remain largely unknown. The objective of this study was to examine the effects of colistin on the blood-brain barrier (BBB) and amino acid neurotransmitters in the cerebral cortex of mouse. Mice were divided into four groups (n=5) and were administrated intravenously with 15mg/kg/day of colistin sulfate for 1, 3 and 7days successively while the control group was administrated intravenously with saline solution. The permeability and ultrastructure of the BBB were detected using the Evans blue (EB) dye and transmission electron microscopy (TEM), and the expression of Claudin-5 were determined by real-time PCR examination and western blotting. The brain uptake of colistin was measured by high-performance liquid chromatography (HPLC). The effects of colistin on amino acid neurotransmitters and their receptors were also examined by HPLC and real-time PCR. The results of EB extravasation, TEM and expression of Claudin-5 showed that colistin treatment did not affect the BBB integrity. In addition, multiple doses of colistin could induce accumulation of this compound in the brain parenchyma although there was poor brain uptake of colistin. Moreover, colistin exposure significantly increased the contents of glutamate (Glu) and gamma aminobutyric acid (GABA), and enhanced the mRNA expression levels of gamma aminobutyric acid type A receptor (GABAAR), gamma aminobutyric acid type B receptor (GABABR), N-methyl-d-aspartate 1 receptor (NR1), N-methyl-d-aspartate 2A receptor (NR2A) and N-methyl-d-aspartate 2B receptor (NR2B) in the cerebral cortex. Our data demonstrate that colistin is able to accumulate in the mouse brain and elevate the levels of amino acid neurotransmitters. These findings may be associated with colistin-induced neurotoxicity.

  6. Differential effects of ethanol on regional glutamatergic and GABAergic neurotransmitter pathways in mouse brain.

    PubMed

    Tiwari, Vivek; Veeraiah, Pandichelvam; Subramaniam, Vaidyanathan; Patel, Anant Bahadur

    2014-03-01

    This study investigates the effects of ethanol on neuronal and astroglial metabolism using (1)H-[(13)C]-NMR spectroscopy in conjunction with infusion of [1,6-(13)C2]/[1-(13)C]glucose or [2-(13)C]acetate, respectively. A three-compartment metabolic model was fitted to the (13)C turnover of GluC3 , GluC4, GABAC 2, GABAC 3, AspC3 , and GlnC4 from [1,6-(13)C2 ]glucose to determine the rates of tricarboxylic acid (TCA) and neurotransmitter cycle associated with glutamatergic and GABAergic neurons. The ratio of neurotransmitter cycle to TCA cycle fluxes for glutamatergic and GABAegic neurons was obtained from the steady-state [2-(13)C]acetate experiment and used as constraints during the metabolic model fitting. (1)H MRS measurement suggests that depletion of ethanol from cerebral cortex follows zero order kinetics with rate 0.18 ± 0.04 μmol/g/min. Acute exposure of ethanol reduces the level of glutamate and aspartate in cortical region. GlnC4 labeling was found to be unchanged from a 15 min infusion of [2-(13)C]acetate suggesting that acute ethanol exposure does not affect astroglial metabolism in naive mice. Rates of TCA and neurotransmitter cycle associated with glutamatergic and GABAergic neurons were found to be significantly reduced in cortical and subcortical regions. Acute exposure of ethanol perturbs the level of neurometabolites and decreases the excitatory and inhibitory activity differentially across the regions of brain. Depletion of ethanol and its effect on brain functions were measured using (1)H and (1)H-[(13)C]-NMR spectroscopy in conjunction with infusion of (13)C-labeled substrates. Ethanol depletion from brain follows zero order kinetics. Ethanol perturbs level of glutamate, and the excitatory and inhibitory activity in mice brain.

  7. Acute Exposure to Pacific Ciguatoxin Reduces Electroencephalogram Activity and Disrupts Neurotransmitter Metabolic Pathways in Motor Cortex.

    PubMed

    Kumar, Gajendra; Au, Ngan Pan Bennett; Lei, Elva Ngai Yu; Mak, Yim Ling; Chan, Leanne Lai Hang; Lam, Michael Hon Wah; Chan, Leo Lai; Lam, Paul Kwan Sing; Ma, Chi Him Eddie

    2016-09-10

    Ciguatera fish poisoning (CFP) is a common human food poisoning caused by consumption of ciguatoxin (CTX)-contaminated fish affecting over 50,000 people worldwide each year. CTXs are classified depending on their origin from the Pacific (P-CTXs), Indian Ocean (I-CTXs), and Caribbean (C-CTXs). P-CTX-1 is the most toxic CTX known and the major source of CFP causing an array of neurological symptoms. Neurological symptoms in some CFP patients last for several months or years; however, the underlying electrophysiological properties of acute exposure to CTXs remain unknown. Here, we used CTX purified from ciguatera fish sourced in the Pacific Ocean (P-CTX-1). Delta and theta electroencephalography (EEG) activity was reduced remarkably in 2 h and returned to normal in 6 h after a single exposure. However, second exposure to P-CTX-1 induced not only a further reduction in EEG activities but also a 2-week delay in returning to baseline EEG values. Ciguatoxicity was detected in the brain hours after the first and second exposure by mouse neuroblastoma assay. The spontaneous firing rate of single motor cortex neuron was reduced significantly measured by single-unit recording with high spatial resolution. Expression profile study of neurotransmitters using targeted profiling approach based on liquid chromatography-tandem mass spectrometry revealed an imbalance between excitatory and inhibitory neurotransmitters in the motor cortex. Our study provides a possible link between the brain oscillations and neurotransmitter release after acute exposure to P-CTX-1. Identification of EEG signatures and major metabolic pathways affected by P-CTX-1 provides new insight into potential biomarker development and therapeutic interventions.

  8. Secondary neurotransmitter deficiencies in epilepsy caused by voltage-gated sodium channelopathies: A potential treatment target?

    PubMed

    Horvath, Gabriella A; Demos, Michelle; Shyr, Casper; Matthews, Allison; Zhang, Linhua; Race, Simone; Stockler-Ipsiroglu, Sylvia; Van Allen, Margot I; Mancarci, Ogan; Toker, Lilah; Pavlidis, Paul; Ross, Colin J; Wasserman, Wyeth W; Trump, Natalie; Heales, Simon; Pope, Simon; Cross, J Helen; van Karnebeek, Clara D M

    2016-01-01

    We describe neurotransmitter abnormalities in two patients with drug-resistant epilepsy resulting from deleterious de novo mutations in sodium channel genes. Whole exome sequencing identified a de novo SCN2A splice-site mutation (c.2379+1G>A, p.Glu717Gly.fs*30) resulting in deletion of exon 14, in a 10-year old male with early onset global developmental delay, intermittent ataxia, autism, hypotonia, epileptic encephalopathy and cerebral/cerebellar atrophy. In the cerebrospinal fluid both homovanillic acid and 5-hydroxyindoleacetic acid were significantly decreased; extensive biochemical and genetic investigations ruled out primary neurotransmitter deficiencies and other known inborn errors of metabolism. In an 8-year old female with an early onset intractable epileptic encephalopathy, developmental regression, and progressive cerebellar atrophy, a previously unreported de novo missense mutation was identified in SCN8A (c.5615G>A; p.Arg1872Gln), affecting a highly conserved residue located in the C-terminal of the Nav1.6 protein. Aside from decreased homovanillic acid and 5-hydroxyindoleacetic acid, 5-methyltetrahydrofolate was also found to be low. We hypothesize that these channelopathies cause abnormal synaptic mono-amine metabolite secretion/uptake via impaired vesicular release and imbalance in electrochemical ion gradients, which in turn aggravate the seizures. Treatment with oral 5-hydroxytryptophan, l-Dopa/Carbidopa, and a dopa agonist resulted in mild improvement of seizure control in the male case, most likely via dopamine and serotonin receptor activated signal transduction and modulation of glutamatergic, GABA-ergic and glycinergic neurotransmission. Neurotransmitter analysis in other sodium channelopathy patients will help validate our findings, potentially yielding novel treatment opportunities.

  9. Self administration of oxycodone by adolescent and adult mice affects striatal neurotransmitter receptor gene expression.

    PubMed

    Mayer-Blackwell, B; Schlussman, S D; Butelman, E R; Ho, A; Ott, J; Kreek, M J; Zhang, Y

    2014-01-31

    Illicit use of prescription opioid analgesics (e.g., oxycodone) in adolescence is a pressing public health issue. Our goal was to determine whether oxycodone self administration differentially affects striatal neurotransmitter receptor gene expression in the dorsal striatum of adolescent compared to adult C57BL/6J mice. Groups of adolescent mice (4 weeks old, n=12) and of adult mice (11 weeks old, n=11) underwent surgery during which a catheter was implanted into their jugular veins. After recovering from surgery, mice self administered oxycodone (0.25 mg/kg/infusion) 2 h/day for 14 consecutive days or served as yoked saline controls. Mice were sacrificed within 1h after the last self-administration session and the dorsal striatum was isolated for mRNA analysis. Gene expression was analyzed with real time PCR using a commercially available neurotransmitter receptor PCR array containing 84 genes. We found that adolescent mice self administered less oxycodone than adult mice over the 14 days. Monoamine oxidase A (Maoa) and neuropeptide Y receptor 5 mRNA levels were lower in adolescent mice than in adult mice without oxycodone exposure. Oxycodone self administration increased Maoa mRNA levels compared to controls in both age groups. There was a positive correlation of the amount of oxycodone self administered in the last session or across 14 sessions with Maoa mRNA levels. Gastrin-releasing peptide receptor mRNA showed a significant Drug × Age interaction, with point-wise significance. More genes in the dorsal striatum of adolescents (19) changed in response to oxycodone self administration compared to controls than in adult (4) mice. Overall, this study demonstrates that repeated oxycodone self administration alters neurotransmitter receptors gene expression in the dorsal striatum of adolescent and adult mice.

  10. Familial orthostatic tachycardia due to norepinephrine transporter deficiency

    NASA Technical Reports Server (NTRS)

    Robertson, D.; Flattem, N.; Tellioglu, T.; Carson, R.; Garland, E.; Shannon, J. R.; Jordan, J.; Jacob, G.; Blakely, R. D.; Biaggioni, I.

    2001-01-01

    Orthostatic intolerance (OI) or postural tachycardia syndrome (POTS) is a syndrome primarily affecting young females, and is characterized by lightheadedness, palpitations, fatigue, altered mentation, and syncope primarily occurring with upright posture and being relieved by lying down. There is typically tachycardia and raised plasma norepinephrine levels on upright posture, but little or no orthostatic hypotension. The pathophysiology of OI is believed to be very heterogeneous. Most studies of the syndrome have focused on abnormalities in norepinephrine release. Here the hypothesis that abnormal norepinephrine transporter (NET) function might contribute to the pathophysiology in some patients with OI was tested. In a proband with significant orthostatic symptoms and tachycardia, disproportionately elevated plasma norepinephrine with standing, impaired systemic, and local clearance of infused tritiated norepinephrine, impaired tyramine responsiveness, and a dissociation between stimulated plasma norepinephrine and DHPG elevation were found. Studies of NET gene structure in the proband revealed a coding mutation that converts a highly conserved transmembrane domain Ala residue to Pro. Analysis of the protein produced by the mutant cDNA in transfected cells demonstrated greater than 98% reduction in activity relative to normal. NE, DHPG/NE, and heart rate correlated with the mutant allele in this family. CONCLUSION: These results represent the first identification of a specific genetic defect in OI and the first disease linked to a coding alteration in a Na+/Cl(-)-dependent neurotransmitter transporter. Identification of this mechanism may facilitate our understanding of genetic causes of OI and lead to the development of more effective therapeutic modalities.

  11. In Vivo Assessment of Neurotransmitters and Modulators with Magnetic Resonance Spectroscopy: Application to Schizophrenia

    PubMed Central

    Wijtenburg, S. Andrea; Yang, Shaolin; Fischer, Bernard A.; Rowland, Laura M.

    2015-01-01

    In vivo measurement of neurotransmitters and modulators is now feasible with advanced proton magnetic resonance spectroscopy (1H-MRS) techniques. This review provides a basic tutorial of MRS, describes the methods available to measure brain glutamate, glutamine, γ-aminobutyric acid, glutathione, N-acetylaspartylglutamate, glycine, and serine at magnetic field strengths of 3Tesla or higher, and summarizes the neurochemical findings in schizophrenia. Overall, 1H-MRS holds great promise for producing biomarkers that can serve as treatment targets, prediction of disease onset, or illness exacerbation in schizophrenia and other brain diseases. PMID:25614132

  12. Noncovalent Complexation of Monoamine Neurotransmitters and Related Ammonium Ions by Tetramethoxy Tetraglucosylcalix[4]arene

    NASA Astrophysics Data System (ADS)

    Torvinen, Mika; Kalenius, Elina; Sansone, Francesco; Casnati, Alessandro; Jänis, Janne

    2012-02-01

    The noncovalent complexation of monoamine neurotransmitters and related ammonium and quaternary ammonium ions by a conformationally flexible tetramethoxy glucosylcalix[4]arene was studied by electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. The glucosylcalixarene exhibited highest binding affinity towards serotonin, norepinephrine, epinephrine, and dopamine. Structural properties of the guests, such as the number, location, and type of hydrogen bonding groups, length of the alkyl spacer between the ammonium head-group and the aromatic ring structure, and the degree of nitrogen substitution affected the complexation. Competition experiments and guest-exchange reactions indicated that the hydroxyl groups of guests participate in intermolecular hydrogen bonding with the glucocalixarene.

  13. Modulation of extracellular neurotransmitter levels in the nucleus accumbens by a taurine uptake inhibitor.

    PubMed

    Olive, M F; Mehmert, K K; Hodge, C W

    2000-12-15

    Using in vivo microdialysis, we examined the effect of local perfusion of the taurine uptake inhibitor guanidinoethyl sulfonate on extracellular levels of various neurotransmitters in the rat nucleus accumbens. Guanidinoethyl sulfonate (500 microM-50 mM) produced a concentration-dependent increase in extracellular taurine levels. While 500 microM and 5 mM concentrations of guanidinoethyl sulfonate were largely without effect, 50 mM guanidinoethyl sulfonate produced a significant decrease in extracellular levels of aspartate, glutamate and glycine, with no effect on extracellular dopamine levels. These results indicate that guanidinoethyl sulfonate can modulate extracellular amino acid levels in the nucleus accumbens.

  14. Synaptic optical imaging platforms: Examining pharmacological modulation of neurotransmitter release at discrete synapses.

    PubMed

    Merchant, Paolomi; Sulzer, David; Sames, Dalibor

    2015-11-01

    Chemical synapses are not only fundamental functional units of the brain but also anatomical and functional biomarkers of numerous brain disorders. Therefore, new experimental readouts of synaptic function are needed--with the spatial resolution of single synapses and the scale to image large ensembles of synapses in specific circuits--for the study of both acute and chronic effects of pharmacological agents on synaptic plasticity in living mammals. In this article we discuss the design and use of fluorescent false neurotransmitters (FFNs) as an important step in the development of versatile synaptic imaging platforms. This article is part of the Special Issue entitled 'Fluorescent Tools in Neuropharmacology'.

  15. Exploration of inclusion complexes of neurotransmitters with β-cyclodextrin by physicochemical techniques

    NASA Astrophysics Data System (ADS)

    Roy, Mahendra Nath; Saha, Subhadeep; Kundu, Mitali; Saha, Binoy Chandra; Barman, Siti

    2016-07-01

    Molecular assemblies of β-cyclodextrin with few of the most important neurotransmitters, viz., dopamine hydrochloride, tyramine hydrochloride and (±)-epinephrine hydrochloride in aqueous medium have been explored by reliable spectroscopic and physicochemical techniques as potential drug delivery systems. Job plots confirm the 1:1 host-guest inclusion complexes, while surface tension and conductivity studies illustrate the inclusion process. The inclusion complexes were characterized by 1H NMR spectroscopy and association constants have been calculated by using Benesi-Hildebrand method. Thermodynamic parameters for the formation of inclusion complexes have been derived by van't Hoff equation, which demonstrate that the overall inclusion processes are thermodynamically favorable.

  16. Coexistence of Several Putative Neurotransmitters in Single Identified Neurosn of Aplysia

    PubMed Central

    Brownstein, Michael J.; Saavedra, Juan M.; Axelrod, Julius; Zeman, Gary H.; Carpenter, David O.

    1974-01-01

    By sensitive enzymatic micromethods several putative neurotransmitters were measured in four identifiable neurons of Aplysia californica (R-2, R-14, L-11, and C-1). Serotonin was found in all of these neurons, and octopamine in all but C-1. Acetylcholine has been previously reported to be present in R-2 and L-11. The catecholamines, norepinephrine and dopamine, were not detected in the four cells examined. The possible biological consequence of the presence of several putative transmitters in single identifiable neurons is discussed. PMID:4373726

  17. HPLC-ESI-MS/MS of brain neurotransmitter modulator lobeline and related piperidine alkaloids in Lobelia inflata L.

    PubMed

    Kursinszki, László; Szőke, Éva

    2015-05-01

    There is a renewed interest in lobelia alkaloids because of their activity on the central nervous system. Lobeline, the most active of them, a nicotinic receptor ligand and neurotransmitter transporter inhibitor, is a candidate pharmacotherapy for metamphetamine abuse. In the present work, high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry in positive ion mode was used for investigating the alkaloid profile in Lobelia inflata L. Chromatographic separations were achieved on a Gemini C6-phenyl reversed-phase column providing good peak shape and improved selectivity. Being mostly 2,6-disubstituted piperidines, lobelia alkaloids presented abundant [M + H](+) ions with typical fragmentation. Identification was possible from a few specific ions, especially those resulting from excision of one of the substituents. Based on fragmentation pattern of lobeline as reference compound, 52 alkaloids were identified in the aqueous methanolic extract of L. inflata in contrast to the previously known some 20. Structural variability of these alkaloids identified arises basically from their substituents which can be phenyl-2-ketoethyl- or phenyl-2-hydroxyethyl units as well as their methyl-, ethyl- or propyl- homologues attached in different combinations. Several propyl homologue lobelia alkaloids and five hydroxypiperidine derivatives were found in the plant at the first time. In addition to 8-O-esters of 2-monosubstituted piperidine alkaloids previously reported by us in L. inflata, a 3-hydroxy-3-phenylpropanoic acid ester of hydroxyallosedamine ring-substituted was also identified as a new natural product. High-performance liquid chromatography-electrospray ionization tandem mass spectrometry can be successfully applied to Lobeliacae plant samples in the routine screening for new and known bioactive constituents, quality control of the crude drug, lobelia herba, alkaloid production studies, breeding and chemotaxonomy.

  18. EDITORIAL: Focus on Graphene

    NASA Astrophysics Data System (ADS)

    Peres, N. M. R.; Ribeiro, Ricardo M.

    2009-09-01

    Graphene physics is currently one of the most active research areas in condensed matter physics. Countless theoretical and experimental studies have already been performed, targeting electronic, magnetic, thermal, optical, structural and vibrational properties. Also, studies that modify pristine graphene, aiming at finding new physics and possible new applications, have been considered. These include patterning nanoribbons and quantum dots, exposing graphene's surface to different chemical species, studying multilayer systems, and inducing strain and curvature (modifying in this way graphene's electronic properties). This focus issue includes many of the latest developments on graphene research. Focus on Graphene Contents Electronic properties of graphene and graphene nanoribbons with 'pseudo-Rashba' spin-orbit coupling Tobias Stauber and John Schliemann Strained graphene: tight-binding and density functional calculations R M Ribeiro, Vitor M Pereira, N M R Peres, P R Briddon and A H Castro Neto The effect of sublattice symmetry breaking on the electronic properties of doped graphene A Qaiumzadeh and R Asgari Interfaces within graphene nanoribbons J Wurm, M Wimmer, I Adagideli, K Richter and H U Baranger Weak localization and transport gap in graphene antidot lattices J Eroms and D Weiss Electronic properties of graphene antidot lattices J A Fürst, J G Pedersen, C Flindt, N A Mortensen, M Brandbyge, T G Pedersen and A-P Jauho Splitting of critical energies in the n=0 Landau level of graphene Ana L C Pereira Double-gated graphene-based devices S Russo, M F Craciun, M Yamamoto, S Tarucha and A F Morpurgo Pinning and switching of magnetic moments in bilayer graphene Eduardo V Castro, M P López-Sancho and M A H Vozmediano Electronic transport properties of graphene nanoribbons Katsunori Wakabayashi, Yositake Takane, Masayuki Yamamoto and Manfred Sigrist Many-body effects on out-of-plane phonons in graphene J González and E Perfetto Graphene zigzag ribbons, square

  19. Diffusiophoretic Focusing of Suspended Colloids

    NASA Astrophysics Data System (ADS)

    Shi, Nan; Nery-Azevedo, Rodrigo; Abdel-Fattah, Amr I.; Squires, Todd M.

    2016-12-01

    Using a microfluidic system to impose and maintain controlled, steady-state multicomponent p H and electrolyte gradients, we present systems where the diffusiophoretic migration of suspended colloids leads them to focus at a particular position, even in steady-state gradients. We show that naively superpositing effects of each gradient may seem conceptually and qualitatively reasonable, yet is invalid due to the coupled transport of these multicomponent electrolytes. In fact, reformulating the classic theories in terms of the flux of each species (rather than local gradients) reveals rather stringent conditions that are necessary for diffusiophoretic focusing in steady gradients. Either particle surface properties must change as a function of local composition in solution (akin to isoelectric focusing in electrophoresis), or chemical reactions must occur between electrolyte species, for such focusing to be possible. The generality of these findings provides a conceptual picture for understanding, predicting, or designing diffusiophoretic systems.

  20. Simulations of neutralized final focus

    SciTech Connect

    Welch, D.R.; Rose, D.V.; Genoni, T.C.; Yu, S.S.; Barnard, J.J.

    2005-01-18

    In order to drive an inertial fusion target or study high energy density physics with heavy ion beams, the beam radius must be focused to < 3 mm and the pulse length must be compressed to < 10 ns. The conventional scheme for temporal pulse compression makes use of an increasing ion velocity to compress the beam as it drifts and beam space charge to stagnate the compression before final focus. Beam compression in a neutralizing plasma does not require stagnation of the compression, enabling a more robust method. The final pulse shape at the target can be programmed by an applied velocity tilt. In this paper, neutralized drift compression is investigated. The sensitivity of the compression and focusing to beam momentum spread, plasma, and magnetic field conditions is studied with realistic driver examples. Using the 3D particle-in-cell code, we examine issues associated with self-field generation, stability, and vacuum-neutralized transport transition and focusing.

  1. Effect of handling on neurotransmitter profile in pig brain according to fear related behaviour.

    PubMed

    Arroyo, Laura; Carreras, Ricard; Valent, Daniel; Peña, Raquel; Mainau, Eva; Velarde, Antonio; Sabrià, Josefa; Bassols, Anna

    2016-12-01

    Chemical neurotransmitters (NT) are principal actors in all neuronal networks of animals. The central nervous system plays an important role in stress susceptibility and organizes the response to a stressful situation through the interaction of the dopaminergic and the serotonergic pathways, leading to the activation of the hypothalamus-pituitary-adrenal axis (HPA). This study was designed to investigate: a) the effects of stressful handling of pigs at the slaughterhouse on the neurotransmitter profile in four brain areas: amygdala, prefrontal cortex (PFC), hippocampus and hypothalamus, and b) whether the alterations in the brain NT profile after stressful handling were associated with fear, determined by the tonic immobility (TI) test. In the first place, the characterization of the NT profile allowed to distinguish the four brain areas in a principal component analysis. The most crucial pathway involved in the reaction of pigs to a stressful handling was the serotonergic system, and changes were observed in the amygdala with a decrease in serotonin (5-HT) and total indoleamines, and in the hippocampus, where this pathway was activated. Fearful and non-fearful pigs did not show significant differences in their NT profile in control conditions, but when subjected to a stressful handling in the slaughterhouse, fearful animals showed a significant variation in the serotonin pathway and, in a lesser extent, the dopamine (DA) pathway. In conclusion, the existence of an underlying biological trait - possibly fearfulness - may be involved in the pig's response toward stressful challenges, and the serotonergic system seems to play a central role in this response.

  2. Genetic variants of neurotransmitter-related genes and miRNAs in Egyptian autistic patients.

    PubMed

    Salem, Ahmed M; Ismail, Samira; Zarouk, Waheba A; Abdul Baky, Olwya; Sayed, Ahmed A; Abd El-Hamid, Sawsan; Salem, Sohair

    2013-01-01

    Autism is a neurodevelopmental disorder with indisputable evidence for a genetic component. This work studied the association of autism with genetic variations in neurotransmitter-related genes, including MAOA uVNTR, MAOB rs1799836, and DRD2 TaqI A in 53 autistic patients and 30 healthy individuals. The study also analyzed sequence variations of miR-431 and miR-21. MAOA uVNTR was genotyped by PCR, MAOB and DRD2 polymorphisms were analyzed by PCR-based RFLP, and miR-431 and miR-21 were sequenced. Low expressing allele of MAOA uVNTR was frequently higher in female patients compared to that in controls (OR = 2.25). MAOB G allele frequency was more significantly increased in autistic patients than in controls (P < 0.001 for both males and females). DRD2 A1+ genotype increased autism risk (OR = 5.1). Severity of autism tends to be slightly affected by MAOA/B genotype. Plasma MAOB activity was significantly reduced in G than in A allele carrying males. There was no significant difference in patients and maternal plasma MAOA/B activity compared to controls. Neither mutations nor SNPs in miR-431 and miR-21 were found among studied patients. This study threw light on some neurotransmitter-related genes suggesting their potential role in Autism pathogenesis that warrants further studies and much consideration.

  3. Determination of neurotransmitter levels in models of Parkinson's disease by HPLC-ECD.

    PubMed

    Yang, Lichuan; Beal, M Flint

    2011-01-01

    Parkinson's disease (PD) is a neurological disorder caused by progressive degeneration of dopaminergic neurons in the nigrostriatal area of the brain. The decrease in dopamine (DA) neurotransmitter levels in the striatum and substantia nigra pars compacta is a neurochemistry hallmark of PD. Therefore, determination of dopamine and its metabolites levels in biological samples provides an important key to understanding the neurochemistry profile of PD. This chapter describes the use of reversed-phase HPLC with electrochemical detection (ECD) for simultaneously measuring monoamine neurotransmitters, including dopamine and its metabolites, norepinephrine as well as serotonin and its metabolite. ECD provides an ultrasensitive measurement, which detects at the picogram level. One run for each sample finishes within 18 min, shows clear chromatographic peaks and a complete separation, and produces excellent precision and reproducibility. Once set up, HPLC-ECD is economic and efficient for analyzing a large number of samples. This method has been broadly used for analyzing a variety of biological samples, such as cerebrospinal fluids, plasma, microdialysis elutes, tissues, and cultured cells. In recent days, it has been reported to be able to detect the dopamine level in a single drosophila head.

  4. Metabolic Profiling and Quantification of Neurotransmitters in Mouse Brain by Gas Chromatography-Mass Spectrometry.

    PubMed

    Jäger, Christian; Hiller, Karsten; Buttini, Manuel

    2016-09-01

    Metabolites are key mediators of cellular functions, and have emerged as important modulators in a variety of diseases. Recent developments in translational biomedicine have highlighted the importance of not looking at just one disease marker or disease inducing molecule, but at populations thereof to gain a global understanding of cellular function in health and disease. The goal of metabolomics is the systematic identification and quantification of metabolite populations. One of the most pressing issues of our times is the understanding of normal and diseased nervous tissue functions. To ensure high quality data, proper sample processing is crucial. Here, we present a method for the extraction of metabolites from brain tissue, their subsequent preparation for non-targeted gas chromatography-mass spectrometry (GC-MS) measurement, as well as giving some guidelines for processing of raw data. In addition, we present a sensitive screening method for neurotransmitters based on GC-MS in selected ion monitoring mode. The precise multi-analyte detection and quantification of amino acid and monoamine neurotransmitters can be used for further studies such as metabolic modeling. Our protocol can be applied to shed light on nervous tissue function in health, as well as neurodegenerative disease mechanisms and the effect of experimental therapeutics at the metabolic level. © 2016 by John Wiley & Sons, Inc.

  5. Effects of delayed treatment with nebracetam on neurotransmitters in brain regions after microsphere embolism in rats

    PubMed Central

    Takeo, Satoshi; Hayashi, Hideki; Miyake, Keiko; Takagi, Kaori; Tadokoro, Mina; Takagi, Norio; Oshikawa, Sayuri

    1997-01-01

    The effects of delayed treatment with nebracetam, a novel nootropic drug, on neurotransmitters of brain regions were examined in rats with microsphere embolism-induced cerebral ischaemia. Cerebral ischaemia was induced by administration of 900 microspheres (48 μm) into the internal carotid artery. The rats with stroke-like symptoms were treated p.o. with 30 mg kg−1 nebracetam twice daily. The levels of acetylcholine, dopamine, noradrenaline, 5-hydroxytryptamine (5-HT) and their metabolites in the cerebral cortex, striatum and hippocampus of animals with microsphere embolism were determined by high performance liquid chromatography (h.p.l.c.) on the 3rd and 7th days after the operation. Although the microsphere embolism induced significant changes in most of the neurotransmitters and some of their metabolites in the brain regions, the delayed treatment with nebracetam partially restored only the hippocampal 5-HT and the striatal dopamine metabolite contents on the 3rd day. The hippocampal in vivo 5-HT synthesis, but not the striatal dopamine synthesis, was attenuated in rats with microsphere embolism on the 3rd day, but was restored by treatment with nebracetam. In vivo striatal dopamine turnover rate of the rats with microsphere embolism was inhibited on the 3rd day irrespective of treatment with nebracetam. The present study provides evidence for a possible action of nebracetam on 5-HT metabolism in the ischaemic brain. PMID:9179389

  6. Effect of champagne compared to still white wine on peripheral neurotransmitter concentrations.

    PubMed

    Boyer, Jean-Christophe; Bancel, Etiennette; Perray, Pascale Fabbro; Pouderoux, Philippe; Balmes, Jean-Louis; Bali, Jean-Pierre

    2004-09-01

    To evaluate how the peripheral release of neurotransmitters such as serotonin, dopamine, cholecystokinin, and beta-endorphin is involved in drinking behavior, blood concentrations of these neurotransmitters were followed in 40 healthy young volunteers during the first hour after ingestion of a moderate dose of some common alcoholic beverages (champagne, still white wine) as compared to water. Concerning serotonin levels, two groups of subjects are statistically distinct: one with low basal serotonin levels (< 620 nmol/L) which responded with an increase in serotonin (52% in 10 minutes), and a second group with higher basal serotonin levels (> 620 nmol/L) which responded with a decrease ( 190% in 60 minutes). Variations in serotonin concentrations appear to depend upon the alcoholic content of the beverage. A rapid increase in plasma dopamine concentrations after consumption of champagne seems to be due to the nonalcoholic content of the beverage. Cholecystokinin values were not significantly different between the three beverages: the observed increase can be explained by a moderate gastric distention. Beta-endorphin levels didn't change significantly after drinking. In conclusion, some significant blood variations of serotonin and dopamine appeared even after moderately dose of champagne or still white wine. These changes might be partially responsible for the different drinking behavior.

  7. Chiral analysis of neurotransmitters using cyclodextrin-modified capillary electrophoresis equipped with microfabricated interdigitated electrodes.

    PubMed

    Male, Keith B; Luong, John H T

    2003-06-27

    We present cyclodextrin-modified capillary electrophoresis equipped with a microfabricated chip consisting of an array of eight interdigitated microband platinum electrodes (IDs) for simultaneous analysis of three chiral models: epinephrine, norepinephrine and isoproterenol. The IDE chip, positioned very close to the capillary outlet, served as an amplification/detection system. Emerging neurotransmitters at the IDE surface were oxidized at +1.1 V by seven electrodes of the array and then detected by the remaining electrode, poised at +0.0 V. There was an amplification effect on the detecting electrode owing to the recycle between the reduced and oxidized forms of the optical isomers at the electrode surface. The detecting "amplification" current response was governed by the applied potential, the detecting electrode position, the number of adjacent electrodes used for recycling and the distance between the oxidative and reductive electrodes. The six chiral forms of the three neurotransmitters were resolved using 25 mM heptakis(2,6,di-o-methyl)-beta-cyclodextrin with a detection limit of approximately 5 microM. The scheme detected a reduced compound at a reducing potential instead of conventional oxidation detection to alleviate electrode fouling and electroactive interferences. The concurrent oxidation/reduction detection of compounds also facilitated and ascertained peak identification as interfering compounds were unlikely to have the same oxidative/reductive characteristics and mobilities as the analytes of interrogation.

  8. Postnatal development of neurotransmitter systems and their relevance to extinction of conditioned fear.

    PubMed

    Kim, Jee Hyun; Perry, Christina J; Ganella, Despina E; Madsen, Heather B

    2017-02-01

    Remembering and forgetting are fundamental features of an organism. Extinction is a type of forgetting where there is a decrease in the significance and/or the meaning of an associative memory when elements of that memory no longer predict one another. The neural mechanisms underlying extinction of fear memories have been extensively studied in the laboratory because extinction processes are clinically relevant to exposure therapies that treat anxiety disorders. However, only in the last decade have we begun to unveil the similarities and differences in plasticity underlying extinction across development. So far it is clear that extinction is a developmentally dissociated process in behavior and in pharmacology, however there are many large gaps in the literature in understanding how the developmental trajectory of different neurotransmitters contribute to changes in the nature of extinction across development. We attempt to address these gaps in the present review. Major neurotransmitter systems including the glutamatergic and GABAergic systems, the monoamines, the endogenous opioid and cannabinoid systems, acetylcholines, and neuropeptides such as oxytocin have all been identified to play some role in extinction of fear memories and have been covered in this review. We hope to facilitate more research into mechanisms of extinction at different stages of life, especially noting that mental disorders are increasingly classified as neurodevelopmental disorders.

  9. Evidence for NO. redox form of nitric oxide as nitrergic inhibitory neurotransmitter in gut.

    PubMed

    Goyal, R K; He, X D

    1998-11-01

    A nitric oxide (NO)-like product of the L-arginine NO synthase pathway has been shown to be a major inhibitory neurotransmitter that is involved in the slow component of the inhibitory junction potential (IJP) elicited by stimulation of nonadrenergic, noncholinergic nerves. However, the exact nature of the nitrergic transmitter, the role of cGMP, and the involvement of a potassium or a chloride conductance in the slow IJP remain unresolved. We examined the effects of soluble guanylate cyclase inhibitors LY-83583 and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), potassium-channel blockers and putative chloride-channel blockers diphenylamine-2-carboxylate (DPC) and niflumic acid (NFA) on the hyperpolarization elicited by an NO. donor, diethylenetriamine/NO adduct (DNO), NO in solution, and an NO+ donor, sodium nitroprusside (SNP), in the guinea pig ileal circular muscle. Effects of these blockers on purinergic (fast) and nitrergic (slow) IJP were also examined. DNO-induced hyperpolarization and nitrergic slow IJP were suppressed by LY-83583 or ODQ and DPC or NFA but not by the potassium-channel blocker apamin. In contrast, hyperpolarization caused by SNP or solubilized NO gas and purinergic fast IJP were antagonized by apamin but not by inhibitors of guanylate cyclase or chloride channels. These results demonstrate biological differences in the actions of different redox states of NO and suggest that NO. is the nitrergic inhibitory neurotransmitter.

  10. Validity of urinary monoamine assay sales under the "spot baseline urinary neurotransmitter testing marketing model".

    PubMed

    Hinz, Marty; Stein, Alvin; Uncini, Thomas

    2011-01-01

    Spot baseline urinary monoamine assays have been used in medicine for over 50 years as a screening test for monoamine-secreting tumors, such as pheochromocytoma and carcinoid syndrome. In these disease states, when the result of a spot baseline monoamine assay is above the specific value set by the laboratory, it is an indication to obtain a 24-hour urine sample to make a definitive diagnosis. There are no defined applications where spot baseline urinary monoamine assays can be used to diagnose disease or other states directly. No peer-reviewed published original research exists which demonstrates that these assays are valid in the treatment of individual patients in the clinical setting. Since 2001, urinary monoamine assay sales have been promoted for numerous applications under the "spot baseline urinary neurotransmitter testing marketing model". There is no published peer-reviewed original research that defines the scientific foundation upon which the claims for these assays are made. On the contrary, several articles have been published that discredit various aspects of the model. To fill the void, this manuscript is a comprehensive review of the scientific foundation and claims put forth by laboratories selling urinary monoamine assays under the spot baseline urinary neurotransmitter testing marketing model.

  11. Near-future carbon dioxide levels alter fish behaviour by interfering with neurotransmitter function

    NASA Astrophysics Data System (ADS)

    Nilsson, Göran E.; Dixson, Danielle L.; Domenici, Paolo; McCormick, Mark I.; Sørensen, Christina; Watson, Sue-Ann; Munday, Philip L.

    2012-03-01

    Predicted future CO2 levels have been found to alter sensory responses and behaviour of marine fishes. Changes include increased boldness and activity, loss of behavioural lateralization, altered auditory preferences and impaired olfactory function. Impaired olfactory function makes larval fish attracted to odours they normally avoid, including ones from predators and unfavourable habitats. These behavioural alterations have significant effects on mortality that may have far-reaching implications for population replenishment, community structure and ecosystem function. However, the underlying mechanism linking high CO2 to these diverse responses has been unknown. Here we show that abnormal olfactory preferences and loss of behavioural lateralization exhibited by two species of larval coral reef fish exposed to high CO2 can be rapidly and effectively reversed by treatment with an antagonist of the GABA-A receptor. GABA-A is a major neurotransmitter receptor in the vertebrate brain. Thus, our results indicate that high CO2 interferes with neurotransmitter function, a hitherto unrecognized threat to marine populations and ecosystems. Given the ubiquity and conserved function of GABA-A receptors, we predict that rising CO2 levels could cause sensory and behavioural impairment in a wide range of marine species, especially those that tightly control their acid-base balance through regulatory changes in HCO3- and Cl- levels.

  12. Expression of functional neurotransmitter receptors in Xenopus oocytes after injection of human brain membranes

    PubMed Central

    Miledi, Ricardo; Eusebi, Fabrizio; Martínez-Torres, Ataúlfo; Palma, Eleonora; Trettel, Flavia

    2002-01-01

    The Xenopus oocyte is a very powerful tool for studies of the structure and function of membrane proteins, e.g., messenger RNA extracted from the brain and injected into oocytes leads to the synthesis and membrane incorporation of many types of functional receptors and ion channels, and membrane vesicles from Torpedo electroplaques injected into oocytes fuse with the oocyte membrane and cause the appearance of functional Torpedo acetylcholine receptors and Cl− channels. This approach was developed further to transplant already assembled neurotransmitter receptors from human brain cells to the plasma membrane of Xenopus oocytes. Membranes isolated from the temporal neocortex of a patient, operated for intractable epilepsy, were injected into oocytes and, within a few hours, the oocyte membrane acquired functional neurotransmitter receptors to γ-aminobutyric acid, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, and glycine. These receptors were also expressed in the plasma membrane of oocytes injected with mRNA extracted from the temporal neocortex of the same patient. All of this makes the Xenopus oocyte a more useful model than it already is for studies of the structure and function of many human membrane proteins and opens the way to novel pathophysiological investigations of some human brain disorders. PMID:12237406

  13. Expression of functional neurotransmitter receptors in Xenopus oocytes after injection of human brain membranes

    NASA Astrophysics Data System (ADS)

    Miledi, Ricardo; Eusebi, Fabrizio; Martínez-Torres, Ataúlfo; Palma, Eleonora; Trettel, Flavia

    2002-10-01

    The Xenopus oocyte is a very powerful tool for studies of the structure and function of membrane proteins, e.g., messenger RNA extracted from the brain and injected into oocytes leads to the synthesis and membrane incorporation of many types of functional receptors and ion channels, and membrane vesicles from Torpedo electroplaques injected into oocytes fuse with the oocyte membrane and cause the appearance of functional Torpedo acetylcholine receptors and Cl channels. This approach was developed further to transplant already assembled neurotransmitter receptors from human brain cells to the plasma membrane of Xenopus oocytes. Membranes isolated from the temporal neocortex of a patient, operated for intractable epilepsy, were injected into oocytes and, within a few hours, the oocyte membrane acquired functional neurotransmitter receptors to -aminobutyric acid, -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, and glycine. These receptors were also expressed in the plasma membrane of oocytes injected with mRNA extracted from the temporal neocortex of the same patient. All of this makes the Xenopus oocyte a more useful model than it already is for studies of the structure and function of many human membrane proteins and opens the way to novel pathophysiological investigations of some human brain disorders.

  14. Cholinergic and other neurotransmitter mechanisms in Parkinson's disease, Parkinson's disease dementia, and dementia with Lewy bodies.

    PubMed

    Francis, Paul T; Perry, Elaine K

    2007-09-01

    It is now 30 years since the beginning of intensive efforts to understand the neurotransmitter biochemistry of dementia as exemplified by Alzheimer's disease and such studies have led to the development of rational treatment strategies, which are continuing to benefit patients. However, as studies became more sophisticated and clinicians rediscovered an interest in dementia, because of the potential for symptomatic treatment, it has become clear that there are several different neurodegenerative conditions that gives rise to dementia syndromes and that each has distinct neurochemical pathology. This has important treatment implications since what works for one may not work for another or at the extreme, may make matters worse. Therefore it is clear that a detailed understanding of the neurotransmitter function in each condition is not merely academic but can lead to rationale drug design and treatment strategies appropriate for that group of patients. Dementia with Lewy bodies (DLB) has clinico-pathological features, which overlap with either AD or Parkinson's disease (PD) as well as features that help to distinguish it, such as fluctuations in cognitive impairment and a higher prevalence of visual hallucinations. On this basis, it would be expected that the neurochemistry would have some similarities with both disorders.

  15. Peptidergic and aminergic neurotransmitters of the exocrine pancreas of the Houbara bustard (Chlamydotis undulata).

    PubMed

    Mensah-Brown, E P; Pallot, D J

    2000-04-01

    The immunochemical distribution of peptidergic and aminergic neurotransmitters in the exocrine pancreas of the Houbara bustard, Chlamydotis undulata, was determined. Immunoreactivity to choline acetyltransferase (ChAT), vasoactive intestinal polypeptide (VIP), and galanin (Gal) occurred mainly as varicose terminals in the walls of capillaries around the acini and arterioles within the connective tissue. Neuronal cell bodies immunoreactive to ChAT were infrequently observed. Neuropeptide Y (NPY), pancreatic polypeptide (PP), and somatostatin (Som) were observed mainly in intra-acinar cell bodies but nerve fibers immunoreactive to these neuropeptides were also seen along the basal surfaces of the acini. Immunoreactivity to NPY and PP was also discernible in cells of the pancreatic ducts. In addition, NPY occurred as varicose terminals in vessels around the ducts. SP occurred rarely in interacinar ganglia. The distribution of tyrosine hydroxylase (TH) was similar to that of ChAT and, in addition, the occasional TH immunoreactive intra-acinar neuronal cell body was observed. Neuronal nitric oxide synthase (nNOS) occurred in neuronal cell bodies among the acinar cells as well as nerve fibers along the bases of the acini. The potential roles of these peptidergic and aminergic neurotransmitters in the neurohormonal control of pancreatic secretion are discussed.

  16. FMRP Regulates Neurotransmitter Release and Synaptic Information Transmission by Modulating Action Potential Duration via BK channels

    PubMed Central

    Deng, Pan-Yue; Rotman, Ziv; Blundon, Jay A.; Cho, Yongcheol; Cui, Jianmin; Cavalli, Valeria; Zakharenko, Stanislav S.; Klyachko, Vitaly A.

    2013-01-01

    SUMMARY Loss of FMRP causes Fragile X syndrome (FXS), but the physiological functions of FMRP remain highly debatable. Here we show that FMRP regulates neurotransmitter release in CA3 pyramidal neurons by modulating action potential (AP) duration. Loss of FMRP leads to excessive AP broadening during repetitive activity, enhanced presynaptic calcium influx and elevated neurotransmitter release. The AP broadening defects caused by FMRP loss have a cell-autonomous presynaptic origin and can be acutely rescued in postnatal neurons. These presynaptic actions of FMRP are translation-independent and are mediated selectively by BK channels via interaction of FMRP with BK channel’s regulatory β4 subunits. Information-theoretical analysis demonstrates that loss of these FMRP functions causes marked dysregulation of synaptic information transmission. FMRP-dependent AP broadening is not limited to the hippocampus, but also occurs in cortical pyramidal neurons. Our results thus suggest major translation-independent presynaptic functions of FMRP that may have important implications for understanding FXS neuropathology. PMID:23439122

  17. Dystrobrevin controls neurotransmitter release and muscle Ca2+ transients by localizing BK channels in C. elegans

    PubMed Central

    Chen, Bojun; Liu, Ping; Zhan, Haiying; Wang, Zhao-Wen

    2011-01-01

    Dystrobrevin is a major component of a dystrophin-associated protein complex (DAPC). It is widely expressed in mammalian tissues including the nervous system, where it is localized to the presynaptic nerve terminal with unknown function. In a genetic screen for suppressors of a lethargic phenotype caused by a gain-of-function (gf) isoform of SLO-1 in C. elegans, we isolated multiple loss-of-function (lf) mutants of the dystrobrevin gene dyb-1. dyb-1(lf) phenocopied slo-1(lf), causing increased neurotransmitter release at the neuromuscular junction, increased frequency of Ca2+ transients in body-wall muscle, and abnormal locomotion behavior. Neuron- and muscle-specific rescue experiments suggest that DYB-1 is required for SLO-1 function in both neurons and muscle cells. DYB-1 colocalized with SLO-1 at presynaptic sites in neurons and dense body regions in muscle cells, and dyb-1(lf) caused SLO-1 mislocalization in both types of cells without altering SLO-1 protein level. The neuronal phenotypes of dyb-1(lf) were partially rescued by mouse α-dystrobrevin-1 (αDB1). These observations revealed novel functions of the BK channel in regulating muscle Ca2+ transients, and of dystrobrevin in controlling neurotransmitter release and muscle Ca2+ transients by localizing the BK channel. PMID:22131396

  18. LKB1 Regulates Mitochondria-Dependent Presynaptic Calcium Clearance and Neurotransmitter Release Properties at Excitatory Synapses along Cortical Axons

    PubMed Central

    Kwon, Seok-Kyu; Sando, Richard; Maximov, Anton; Polleux, Franck

    2016-01-01

    Individual synapses vary significantly in their neurotransmitter release properties, which underlie complex information processing in neural circuits. Presynaptic Ca2+ homeostasis plays a critical role in specifying neurotransmitter release properties, but the mechanisms regulating synapse-specific Ca2+ homeostasis in the mammalian brain are still poorly understood. Using electrophysiology and genetically encoded Ca2+ sensors targeted to the mitochondrial matrix or to presynaptic boutons of cortical pyramidal neurons, we demonstrate that the presence or absence of mitochondria at presynaptic boutons dictates neurotransmitter release properties through Mitochondrial Calcium Uniporter (MCU)-dependent Ca2+ clearance. We demonstrate that the serine/threonine kinase LKB1 regulates MCU expression, mitochondria-dependent Ca2+ clearance, and thereby, presynaptic release properties. Re-establishment of MCU-dependent mitochondrial Ca2+ uptake at glutamatergic synapses rescues the altered neurotransmitter release properties characterizing LKB1-null cortical axons. Our results provide novel insights into the cellular and molecular mechanisms whereby mitochondria control neurotransmitter release properties in a bouton-specific way through presynaptic Ca2+ clearance. PMID:27429220

  19. Impact of Synaptic Neurotransmitter Concentration Time Course on the Kinetics and Pharmacological Modulation of Inhibitory Synaptic Currents

    PubMed Central

    Barberis, Andrea; Petrini, Enrica Maria; Mozrzymas, Jerzy W.

    2011-01-01

    The time course of synaptic currents is a crucial determinant of rapid signaling between neurons. Traditionally, the mechanisms underlying the shape of synaptic signals are classified as pre- and post-synaptic. Over the last two decades, an extensive body of evidence indicated that synaptic signals are critically shaped by the neurotransmitter time course which encompasses several phenomena including pre- and post-synaptic ones. The agonist transient depends on neurotransmitter release mechanisms, diffusion within the synaptic cleft, spill-over to the extra-synaptic space, uptake, and binding to post-synaptic receptors. Most estimates indicate that the neurotransmitter transient is very brief, lasting between one hundred up to several hundreds of microseconds, implying that post-synaptic activation is characterized by a high degree of non-equilibrium. Moreover, pharmacological studies provide evidence that the kinetics of agonist transient plays a crucial role in setting the susceptibility of synaptic currents to modulation by a variety of compounds of physiological or clinical relevance. More recently, the role of the neurotransmitter time course has been emphasized by studies carried out on brain slice models that revealed a striking, cell-dependent variability of synaptic agonist waveforms ranging from rapid pulses to slow volume transmission. In the present paper we review the advances on studies addressing the impact of synaptic neurotransmitter transient on kinetics and pharmacological modulation of synaptic currents at inhibitory synapses. PMID:21734864

  20. Speeding chemical reactions by focusing.

    PubMed

    Lacasta, A M; Ramírez-Piscina, L; Sancho, J M; Lindenberg, K

    2013-04-14

    We present numerical results for a chemical reaction of colloidal particles which are transported by a laminar fluid and are focused by periodic obstacles in such a way that the two components are well mixed and consequently the chemical reaction is speeded up. The roles of the various system parameters (diffusion coefficients, reaction rate, and obstacles sizes) are studied. We show that focusing speeds up the reaction from the diffusion limited rate ∼t(-1/2) to very close to the perfect mixing rate, ∼t(-1).

  1. Speeding chemical reactions by focusing

    NASA Astrophysics Data System (ADS)

    Lacasta, A. M.; Ramírez-Piscina, L.; Sancho, J. M.; Lindenberg, K.

    2013-04-01

    We present numerical results for a chemical reaction of colloidal particles which are transported by a laminar fluid and are focused by periodic obstacles in such a way that the two components are well mixed and consequently the chemical reaction is speeded up. The roles of the various system parameters (diffusion coefficients, reaction rate, and obstacles sizes) are studied. We show that focusing speeds up the reaction from the diffusion limited rate ˜t-1/2 to very close to the perfect mixing rate, ˜t-1.

  2. Molecular Imaging of Transporters with Positron Emission Tomography

    NASA Astrophysics Data System (ADS)

    Antoni, Gunnar; Sörensen, Jens; Hall, Håkan

    Positron emission tomography (PET) visualization of brain components in vivo is a rapidly growing field. Molecular imaging with PET is also increasingly used in drug development, especially for the determination of drug receptor interaction for CNS-active drugs. This gives the opportunity to relate clinical efficacy to per cent receptor occupancy of a drug on a certain targeted receptor and to relate drug pharmacokinetics in plasma to interaction with target protein. In the present review we will focus on the study of transporters, such as the monoamine transporters, the P-glycoprotein (Pgp) transporter, the vesicular monoamine transporter type 2, and the glucose transporter using PET radioligands. Neurotransmitter transporters are presynaptically located and in vivo imaging using PET can therefore be used for the determination of the density of afferent neurons. Several promising PET ligands for the noradrenaline transporter (NET) have been labeled and evaluated in vivo including in man, but a really useful PET ligand for NET still remains to be identified. The most promising tracer to date is (S,S)-[18F]FMeNER-D2. The in vivo visualization of the dopamine transporter (DAT) may give clues in the evaluation of conditions related to dopamine, such as Parkinson's disease and drug abuse. The first PET radioligands based on cocaine were not selective, but more recently several selective tracers such as [11C]PE2I have been characterized and shown to be suitable as PET radioligands. Although there are a large number of serotonin transporter inhibitors used today as SSRIs, it was not until very recently, when [11C]McN5652 was synthesized, that this transporter was studied using PET. New candidates as PET radioligands for the SERT have subsequently been developed and [11C]DASB and [11C]MADAM and their analogues are today the most promising ligands. The existing radioligands for Pgp transporters seem to be suitable tools for the study of both peripheral and central drug

  3. Analysis of amino acid neurotransmitters from rat and mouse spinal cords by liquid chromatography with fluorescence detection.

    PubMed

    Şanlı, Nurullah; Tague, Sarah E; Lunte, Craig

    2015-03-25

    A RP-LC-FL detection method has been developed to identify and quantitate four amino acid neurotransmitters including glutamic acid, glycine, taurine and γ-aminobutyric acid in rat and mouse spinal cord tissue. 3-(4-carboxybenzoyl)-2-quinolinecarboxaldehyde (CBQCA) was employed for the derivatization of these neurotransmitters prior to RP-LC-FL analysis. Different parameters which influenced separation and derivatization were optimized. Under optimum conditions, linearity was achieved within the concentration ranges of 0.50-50.00 μM for all analytes with correlation coefficients from 0.9912 to 0.9997. The LODs ranged from 0.03 μM to 0.06 μM. The proposed method has been successfully applied to the determination of amino acid neurotransmitters in biological samples such as rat and mouse spinal cord with satisfactory recoveries.

  4. [Changes in the activity of the ciliary apparatus of the cerebral aqueduct ependymal cells induced by some cerebrospinal fluid neurotransmitters].

    PubMed

    2010-01-01

    In vitro investigation of the effect of the neurotransmitter amino acids on motile activity of the ciliary apparatus of cerebral (Sylvian) aqueduct ependymal cells in the newborn rats has shown that the addition of glutamate, GABA, glycine, and taurine to the nutrient medium induced deceleration and, finally, complete disappearance of motile activity of the ciliary apparatus. Inhibition and blocking of the ciliary activity induced by the neurotransmitters, especially by high concentrations of glutamate, indicate the existence of respective receptors on the membrane of the cerebral aqueduct ependymal cells. This involvement of the receptors was confirmed in the experiments with the preliminary introduction of ion channel blockers (ketamine, strychnine, and bicuculine) into the culture medium that resulted in the attenuation of neurotransmitter destructive effect and the prolongation of motile activity of the ciliary apparatus.

  5. Impaired learning of predators and lower prey survival under elevated CO2 : a consequence of neurotransmitter interference.

    PubMed

    Chivers, Douglas P; McCormick, Mark I; Nilsson, Göran E; Munday, Philip L; Watson, Sue-Ann; Meekan, Mark G; Mitchell, Matthew D; Corkill, Katherine C; Ferrari, Maud C O

    2014-02-01

    Ocean acidification is one of the most pressing environmental concerns of our time, and not surprisingly, we have seen a recent explosion of research into the physiological impacts and ecological consequences of changes in ocean chemistry. We are gaining considerable insights from this work, but further advances require greater integration across disciplines. Here, we showed that projected near-future CO2 levels impaired the ability of damselfish to learn the identity of predators. These effects stem from impaired neurotransmitter function; impaired learning under elevated CO2 was reversed when fish were treated with gabazine, an antagonist of the GABA-A receptor - a major inhibitory neurotransmitter receptor in the brain of vertebrates. The effects of CO2 on learning and the link to neurotransmitter interference were manifested as major differences in survival for fish released into the wild. Lower survival under elevated CO2 , as a result of impaired learning, could have a major influence on population recruitment.

  6. Secure Transportation Management

    SciTech Connect

    Gibbs, P. W.

    2014-10-15

    Secure Transport Management Course (STMC) course provides managers with information related to procedures and equipment used to successfully transport special nuclear material. This workshop outlines these procedures and reinforces the information presented with the aid of numerous practical examples. The course focuses on understanding the regulatory framework for secure transportation of special nuclear materials, identifying the insider and outsider threat(s) to secure transportation, organization of a secure transportation unit, management and supervision of secure transportation units, equipment and facilities required, training and qualification needed.

  7. "Only" and Focus.

    ERIC Educational Resources Information Center

    Vallduvi, Enric

    The relationship of the word "only," one of a class of words known as scalar particles, focus adverbs, focus inducers, or focus-sensitive particles, with the "focus" of the sentence is examined. It is suggested, based on analysis of discourse structure, that this "association with focus" is not an inherent property of…

  8. Spintronic characteristics of self-assembled neurotransmitter acetylcholine molecular complexes enable quantum information processing in neural networks and brain

    NASA Astrophysics Data System (ADS)

    Tamulis, Arvydas; Majauskaite, Kristina; Kairys, Visvaldas; Zborowski, Krzysztof; Adhikari, Kapil; Krisciukaitis, Sarunas

    2016-09-01

    Implementation of liquid state quantum information processing based on spatially localized electronic spin in the neurotransmitter stable acetylcholine (ACh) neutral molecular radical is discussed. Using DFT quantum calculations we proved that this molecule possesses stable localized electron spin, which may represent a qubit in quantum information processing. The necessary operating conditions for ACh molecule are formulated in self-assembled dimer and more complex systems. The main quantum mechanical research result of this paper is that the neurotransmitter ACh systems, which were proposed, include the use of quantum molecular spintronics arrays to control the neurotransmission in neural networks.

  9. Mechanisms of metabonomic for a gateway drug: nicotine priming enhances behavioral response to cocaine with modification in energy metabolism and neurotransmitter level.

    PubMed

    Li, Hongyu; Bu, Qian; Chen, Bo; Shao, Xue; Hu, Zhengtao; Deng, Pengchi; Lv, Lei; Deng, Yi; Zhu, Ruiming; Li, Yan; Zhang, Baolai; Hou, Jing; Du, Changman; Zhao, Qian; Fu, Dengqi; Zhao, Yinglan; Cen, Xiaobo

    2014-01-01

    Nicotine, one of the most commonly used drugs, has become a major concern because tobacco serves as a gateway drug and is linked to illicit drug abuse, such as cocaine and marijuana. However, previous studies mainly focused on certain genes or neurotransmitters which have already been known to participate in drug addiction, lacking endogenous metabolic profiling in a global view. To further explore the mechanism by which nicotine modifies the response to cocaine, we developed two conditioned place preference (CPP) models in mice. In threshold dose model, mice were pretreated with nicotine, followed by cocaine treatment at the dose of 2 mg/kg, a threshold dose of cocaine to induce CPP in mice. In high-dose model, mice were only treated with 20 mg/kg cocaine, which induced a significant CPP. (1)H nuclear magnetic resonance based on metabonomics was used to investigate metabolic profiles of the nucleus accumbens (NAc) and striatum. We found that nicotine pretreatment dramatically increased CPP induced by 2 mg/kg cocaine, which was similar to 20 mg/kg cocaine-induced CPP. Interestingly, metabolic profiles showed considerable overlap between these two models. These overlapped metabolites mainly included neurotransmitters as well as the molecules participating in energy homeostasis and cellular metabolism. Our results show that the reinforcing effect of nicotine on behavioral response to cocaine may attribute to the modification of some specific metabolites in NAc and striatum, thus creating a favorable metabolic environment for enhancing conditioned rewarding effect of cocaine. Our findings provide an insight into the effect of cigarette smoking on cocaine dependence and the underlying mechanism.

  10. Apparatus and method for performing electrodynamic focusing on a microchip

    DOEpatents

    Ramsey, John Michael; Jacobson, Stephen C.

    1999-01-01

    A microchip device includes a focusing channel, in which an electric field strength established in the focusing channel is controlled relative to an electric field strength established in a material transport channel segment to spatially focus the material traversing the material transport channel segment.

  11. Apparatus and method for performing electrodynamic focusing on a microchip

    DOEpatents

    Ramsey, J.M.; Jacobson, S.C.

    1999-01-12

    A microchip device includes a focusing channel, in which an electric field strength established in the focusing channel is controlled relative to an electric field strength established in a material transport channel segment to spatially focus the material traversing the material transport channel segment. 22 figs.

  12. Microelectronics-Based Biosensors Dedicated to the Detection of Neurotransmitters: A Review

    PubMed Central

    Mirzaei, Maryam; Sawan, Mohamad

    2014-01-01

    Dysregulation of neurotransmitters (NTs) in the human body are related to diseases such as Parkinson's and Alzheimer's. The mechanisms of several neurological disorders, such as epilepsy, have been linked to NTs. Because the number of diagnosed cases is increasing, the diagnosis and treatment of such diseases are important. To detect biomolecules including NTs, microtechnology, micro and nanoelectronics have become popular in the form of the miniaturization of medical and clinical devices. They offer high-performance features in terms of sensitivity, as well as low-background noise. In this paper, we review various devices and circuit techniques used for monitoring NTs in vitro and in vivo and compare various methods described in recent publications. PMID:25264957

  13. Multiple roles of calcium ions in the regulation of neurotransmitter release.

    PubMed

    Neher, Erwin; Sakaba, Takeshi

    2008-09-25

    The intracellular calcium concentration ([Ca(2+)]) has important roles in the triggering of neurotransmitter release and the regulation of short-term plasticity (STP). Transmitter release is initiated by quite high concentrations within microdomains, while short-term facilitation is strongly influenced by the global buildup of "residual calcium." A global rise in [Ca(2+)] also accelerates the recruitment of release-ready vesicles, thereby controlling the degree of short-term depression (STD) during sustained activity, as well as the recovery of the vesicle pool in periods of rest. We survey data that lead us to propose two distinct roles of [Ca(2+)] in vesicle recruitment: one accelerating "molecular priming" (vesicle docking and the buildup of a release machinery), the other promoting the tight coupling between releasable vesicles and Ca(2+) channels. Such coupling is essential for rendering vesicles sensitive to short [Ca(2+)] transients, generated during action potentials.

  14. 'Full fusion' is not ineluctable during vesicular exocytosis of neurotransmitters by endocrine cells.

    PubMed

    Oleinick, Alexander; Svir, Irina; Amatore, Christian

    2017-01-01

    Vesicular exocytosis is an essential and ubiquitous process in neurons and endocrine cells by which neurotransmitters are released in synaptic clefts or extracellular fluids. It involves the fusion of a vesicle loaded with chemical messengers with the cell membrane through a nanometric fusion pore. In endocrine cells, unless it closes after some flickering ('Kiss-and-Run' events), this initial pore is supposed to expand exponentially, leading to a full integration of the vesicle membrane into the cell membrane-a stage called 'full fusion'. We report here a compact analytical formulation that allows precise measurements of the fusion pore expansion extent and rate to be extracted from individual amperometric spike time courses. These data definitively establish that, during release of catecholamines, fusion pores enlarge at most to approximately one-fifth of the radius of their parent vesicle, hence ruling out the ineluctability of 'full fusion'.

  15. Afferent Inputs to Neurotransmitter-Defined Cell Types in the Ventral Tegmental Area.

    PubMed

    Faget, Lauren; Osakada, Fumitaka; Duan, Jinyi; Ressler, Reed; Johnson, Alexander B; Proudfoot, James A; Yoo, Ji Hoon; Callaway, Edward M; Hnasko, Thomas S

    2016-06-21

    The ventral tegmental area (VTA) plays a central role in the neural circuit control of behavioral reinforcement. Though considered a dopaminergic nucleus, the VTA contains substantial heterogeneity in neurotransmitter type, containing also GABA and glutamate neurons. Here, we used a combinatorial viral approach to transsynaptically label afferents to defined VTA dopamine, GABA, or glutamate neurons. Surprisingly, we find that these populations received qualitatively similar inputs, with dominant and comparable projections from the lateral hypothalamus, raphe, and ventral pallidum. However, notable differences were observed, with striatal regions and globus pallidus providing a greater share of input to VTA dopamine neurons, cortical input preferentially on to glutamate neurons, and GABA neurons receiving proportionally more input from the lateral habenula and laterodorsal tegmental nucleus. By comparing inputs to each of the transmitter-defined VTA cell types, this study sheds important light on the systems-level organization of diverse inputs to VTA.

  16. `Full fusion' is not ineluctable during vesicular exocytosis of neurotransmitters by endocrine cells

    NASA Astrophysics Data System (ADS)

    Oleinick, Alexander; Svir, Irina; Amatore, Christian

    2017-01-01

    Vesicular exocytosis is an essential and ubiquitous process in neurons and endocrine cells by which neurotransmitters are released in synaptic clefts or extracellular fluids. It involves the fusion of a vesicle loaded with chemical messengers with the cell membrane through a nanometric fusion pore. In endocrine cells, unless it closes after some flickering (`Kiss-and-Run' events), this initial pore is supposed to expand exponentially, leading to a full integration of the vesicle membrane into the cell membrane-a stage called `full fusion'. We report here a compact analytical formulation that allows precise measurements of the fusion pore expansion extent and rate to be extracted from individual amperometric spike time courses. These data definitively establish that, during release of catecholamines, fusion pores enlarge at most to approximately one-fifth of the radius of their parent vesicle, hence ruling out the ineluctability of `full fusion'.

  17. Photo-renewable electroanalytical sensor for neurotransmitters detection in body fluid mimics.

    PubMed

    Pifferi, Valentina; Soliveri, Guido; Panzarasa, Guido; Cappelletti, Giuseppe; Meroni, Daniela; Falciola, Luigi

    2016-10-01

    A composite electrode with a sandwich structure combining the properties of silver nanoparticles and a titania photoactive layer was used for the electroanalytical detection, by differential pulse voltammetry, of three neurotransmitters: dopamine, norepinephrine, and serotonin. The three analytes were determined at low detection limits (around 0.03 μM) also in the presence of conventional interferents, such as uric and ascorbic acids. The fouling of the electrode surface was overcome by irradiating the device with UVA light, restoring the initial sensor sensitivity. Dopamine, norepinephrine, and serotonin were determined also in simulated biological matrices: liquor (artificially reproduced cerebrospinal fluid) and serum. Moreover, the contemporaneous detection of dopamine and norepinephrine in simulated human urine solutions was also demonstrated, representing the first step towards clinical applications of the proposed methodology. Graphical abstract The photo-renewable electroanalytical sensor.

  18. PRRT2 Is a Key Component of the Ca(2+)-Dependent Neurotransmitter Release Machinery.

    PubMed

    Valente, Pierluigi; Castroflorio, Enrico; Rossi, Pia; Fadda, Manuela; Sterlini, Bruno; Cervigni, Romina Ines; Prestigio, Cosimo; Giovedì, Silvia; Onofri, Franco; Mura, Elisa; Guarnieri, Fabrizia C; Marte, Antonella; Orlando, Marta; Zara, Federico; Fassio, Anna; Valtorta, Flavia; Baldelli, Pietro; Corradi, Anna; Benfenati, Fabio

    2016-04-05

    Heterozygous mutations in proline-rich transmembrane protein 2 (PRRT2) underlie a group of paroxysmal disorders, including epilepsy, kinesigenic dyskinesia, and migraine. Most of the mutations lead to impaired PRRT2 expression, suggesting that loss of PRRT2 function may contribute to pathogenesis. We show that PRRT2 is enriched in presynaptic terminals and that its silencing decreases the number of synapses and increases the number of docked synaptic vesicles at rest. PRRT2-silenced neurons exhibit a severe impairment of synchronous release, attributable to a sharp decrease in release probability and Ca(2+) sensitivity and associated with a marked increase of the asynchronous/synchronous release ratio. PRRT2 interacts with the synaptic proteins SNAP-25 and synaptotagmin 1/2. The results indicate that PRRT2 is intimately connected with the Ca(2+)-sensing machinery and that it plays an important role in the final steps of neurotransmitter release.

  19. Evidence for genetic influences on neurotransmitter content of identified neurones of Lymnaea stagnalis.

    PubMed

    Audesirk, G; Audesirk, T; McCaman, R E; Ono, J K

    1985-01-01

    Neurotransmitter content was measured in two identified giant neurones in isogenic and wild-type populations of the freshwater pond snail Lymnaea stagnalis. The paired serotonergic cerebral giant neurones (LC1 and RC1) have higher transmitter levels and less variability in inbred animals than in wild-type animals. The transmitter content of the unpaired dopaminergic right pedal giant neurone (RPeD1) does not differ between inbred and wild-type animals in either level or variability. It is proposed that serotonin content of the cerebral giant neurones is under partial genetic control, and that animals of the wild-type population may possess a number of different alleles for the genes influencing serotonin levels. Inbreeding resulted in fixation of an allele promoting high serotonin levels. This particular wild-type population is probably already isogenic for genes influencing dopamine content in the right pedal giant neurone.

  20. PRRT2 Is a Key Component of the Ca2+-Dependent Neurotransmitter Release Machinery

    PubMed Central

    Valente, Pierluigi; Castroflorio, Enrico; Rossi, Pia; Fadda, Manuela; Sterlini, Bruno; Cervigni, Romina Ines; Prestigio, Cosimo; Giovedì, Silvia; Onofri, Franco; Mura, Elisa; Guarnieri, Fabrizia C.; Marte, Antonella; Orlando, Marta; Zara, Federico; Fassio, Anna; Valtorta, Flavia; Baldelli, Pietro; Corradi, Anna; Benfenati, Fabio

    2016-01-01

    Summary Heterozygous mutations in proline-rich transmembrane protein 2 (PRRT2) underlie a group of paroxysmal disorders, including epilepsy, kinesigenic dyskinesia, and migraine. Most of the mutations lead to impaired PRRT2 expression, suggesting that loss of PRRT2 function may contribute to pathogenesis. We show that PRRT2 is enriched in presynaptic terminals and that its silencing decreases the number of synapses and increases the number of docked synaptic vesicles at rest. PRRT2-silenced neurons exhibit a severe impairment of synchronous release, attributable to a sharp decrease in release probability and Ca2+ sensitivity and associated with a marked increase of the asynchronous/synchronous release ratio. PRRT2 interacts with the synaptic proteins SNAP-25 and synaptotagmin 1/2. The results indicate that PRRT2 is intimately connected with the Ca2+-sensing machinery and that it plays an important role in the final steps of neurotransmitter release. PMID:27052163

  1. Effects of dietary amino acids, carbohydrates, and choline on neurotransmitter synthesis

    NASA Technical Reports Server (NTRS)

    Wurtman, Richard J.

    1988-01-01

    The ability of a meal to increase or decrease brain neurotransmitter synthesis has been studied. It is concluded that brain serotonin synthesis is directly controlled by the proportions of carbohydrate to protein in meals and snacks that increase or decrease brain tryptophan levels, thereby changing the substrate saturation of tryptophan hydroxylase and the rate of serotonin synthesis. The ability of serotoninergic neurons to have their output coupled to dietary macronutrients enables them to function as sensors of peripheral metabolism, and to subserve an important role in the control of appetite. The robust and selective responses of catecholaminergic and cholinergic neurons to supplemental tyrosine and choline suggest that these compounds may become useful as a new type of drug for treating deseases or conditions in which adequate quantities of the transmitter would otherwise be unavailable.

  2. Microtransplantation of neurotransmitter receptors from postmortem autistic brains to Xenopus oocytes

    PubMed Central

    Limon, Agenor; Reyes-Ruiz, Jorge Mauricio; Miledi, Ricardo

    2008-01-01

    Autism is a complex disorder that arises from the pervasive action of genetic and epigenetic factors that alter synaptic connectivity of the brain. Although GABA and glutamate receptors seem to be two of those factors, very little is known about the functional properties of the autistic receptors. Autistic tissue samples stored in brain banks usually have relatively long postmortem times, and it is highly desirable to know whether neurotransmitter receptors in such tissues are still functional. Here we demonstrate that native receptors microtransplanted from autistic brains, as well as de novo mRNA-expressed receptors, are still functional and susceptible to detailed electrophysiological characterization even after long postmortem intervals. The opportunity to study the properties of human receptors present in diseased brains not only opens new avenues toward understanding autism and other neurological disorders, but it also makes the microtransplantation method a useful translational system to evaluate and develop novel medicinal drugs. PMID:18645182

  3. Microelectronics-based biosensors dedicated to the detection of neurotransmitters: a review.

    PubMed

    Mirzaei, Maryam; Sawan, Mohamad

    2014-09-26

    Dysregulation of neurotransmitters (NTs) in the human body are related to diseases such as Parkinson's and Alzheimer's. The mechanisms of several neurological disorders, such as epilepsy, have been linked to NTs. Because the number of diagnosed cases is increasing, the diagnosis and treatment of such diseases are important. To detect biomolecules including NTs, microtechnology, micro and nanoelectronics have become popular in the form of the miniaturization of medical and clinical devices. They offer high-performance features in terms of sensitivity, as well as low-background noise. In this paper, we review various devices and circuit techniques used for monitoring NTs in vitro and in vivo and compare various methods described in recent publications.

  4. Kv3 voltage-gated potassium channels regulate neurotransmitter release from mouse motor nerve terminals.

    PubMed

    Brooke, Ruth E; Moores, Thomas S; Morris, Neil P; Parson, Simon H; Deuchars, Jim

    2004-12-01

    Voltage-gated potassium (Kv) channels are critical to regulation of neurotransmitter release throughout the nervous system but the roles and identity of the subtypes involved remain unclear. Here we show that Kv3 channels regulate transmitter release at the mouse neuromuscular junction (NMJ). Light- and electron-microscopic immunohistochemistry revealed Kv3.3 and Kv3.4 subunits within all motor nerve terminals of muscles examined [transversus abdominus, lumbrical and flexor digitorum brevis (FDB)]. To determine the roles of these Kv3 subunits, intracellular recordings were made of end-plate potentials (EPPs) in FDB muscle fibres evoked by electrical stimulation of tibial nerve. Tetraethylammonium (TEA) applied at low concentrations (0.05-0.5 mM), which blocks only a few known potassium channels including Kv3 channels, did not affect muscle fibre resting potential but significantly increased the amplitude of all EPPs tested. Significantly, this effect of TEA was still observed in the presence of the large-conductance calcium-activated potassium channel blockers iberiotoxin (25-150 nM) and Penitrem A (100 nM), suggesting a selective action on Kv3 subunits. Consistent with this, 15-microM 4-aminopyridine, which blocks Kv3 but not large-conductance calcium-activated potassium channels, enhanced evoked EPP amplitude. Unexpectedly, blood-depressing substance-I, a toxin selective for Kv3.4 subunits, had no effect at 0.05-1 microM. The combined presynaptic localization of Kv3 subunits and pharmacological enhancement of EPP amplitude indicate that Kv3 channels regulate neurotransmitter release from presynaptic terminals at the NMJ.

  5. Effect of long-term vigabatrin therapy on selected neurotransmitter concentrations in cerebrospinal fluid.

    PubMed

    Ben-Menachem, E; Persson, L I; Mumford, J; Haegele, K D; Huebert, N

    1991-01-01

    Ten patients, suffering from drug-resistant complex partial seizures were treated for a period of up to 3 years with vigabatrin (Sabril). Vigabatrin is a novel antiepileptic agent, whose action is based on the inhibition of gamma-aminobutyric acid (GABA) aminotransferase, the enzyme responsible for the catabolism of the neurotransmitter GABA. Samples of lumbar cerebrospinal fluid were obtained from the patients prior to commencing vigabatrin therapy, and thereafter at 6 months, 1 year, 2 years, and up to 3 years following the initiation of vigabatrin treatment. The influence of vigabatrin on the cerebrospinal fluid concentrations of free and total GABA, homocarnosine, homovanillic acid, 5-hydroxyindoleacetic acid, and 3-methoxy-4-hydroxyphenylethylene glycol, as well as of the drug itself, was assessed. All patients demonstrated a clinical response to vigabatrin, and the drug was well tolerated over the entire observation period. Mean (+/- SD) reduction of seizure frequency was 65% +/- 23% (range, 26% to 100%) when comparing the end of the treatment period to the previgabatrin baseline. The cerebrospinal fluid concentrations of both free and total GABA and of the dipeptide homocarnosine showed approximately 2- to 5-fold increases over baseline values, with free GABA and homocarnosine being the more sensitive variables. Cerebrospinal fluid concentrations of homovanillic acid, 5-hydroxyindoleacetic acid, and 3-methoxy-4-hydroxyphenylethylene glycol were not altered in a significant manner over the observation period. These findings support the concept that the effects of vigabatrin are restricted to an effect on GABA catabolism and do not extend to the neurotransmitters dopamine and norepinephrine. Clinical efficacy and elevation of GABA and homocarnosine concentration were sustained over the period of observation.

  6. Beneficial effects of lycopene against haloperidol induced orofacial dyskinesia in rats: Possible neurotransmitters and neuroinflammation modulation.

    PubMed

    Datta, Swati; Jamwal, Sumit; Deshmukh, Rahul; Kumar, Puneet

    2016-01-15

    Tardive Dyskinesia is a severe side effect of chronic neuroleptic treatment consisting of abnormal involuntary movements, characterized by orofacial dyskinesia. The study was designed to investigate the protective effect of lycopene against haloperidol induced orofacial dyskinesia possibly by neurochemical and neuroinflammatory modulation in rats. Rats were administered with haloperidol (1mg/kg, i.p for 21 days) to induce orofacial dyskinesia. Lycopene (5 and 10mg/kg, p.o) was given daily 1hour before haloperidol treatment for 21 days. Behavioral observations (vacuous chewing movements, tongue protrusions, facial jerking, rotarod activity, grip strength, narrow beam walking) were assessed on 0th, 7th(,) 14th(,) 21st day after haloperidol treatment. On 22nd day, animals were killed and striatum was excised for estimation of biochemical parameters (malondialdehyde, nitrite and endogenous enzyme (GSH), pro-inflammatory cytokines [Tumor necrosis factor, Interleukin 1β, Interleukin 6] and neurotransmitters level (dopamine, serotonin, nor epinephrine, 5-Hydroxyindole acetic acid (5-HIAA), Homovanillic acid, 3,4- dihydroxyphenylacetic acid. Haloperidol treatment for 21 days impaired muscle co-ordination, motor activity and grip strength with an increased in orofacial dyskinetic movements. Further free radical generation increases MDA and nitrite levels, decreasing GSH levels in striatum. Neuroinflammatory markers were significantly increased with decrease in neurotransmitters levels. Lycopene (5 and 10mg/kg, p.o) treatment along with haloperidol significantly attenuated impairment in behavioral, biochemical, neurochemical and neuroinflammatory markers. Results of the present study attributed the therapeutic potential of lycopene in the treatment (prevented or delayed) of typical antipsychotic induced orofacial dyskinesia.

  7. Developmental origins of neurotransmitter and transcriptome alterations in adult female zebrafish exposed to atrazine during embryogenesis.

    PubMed

    Wirbisky, Sara E; Weber, Gregory J; Sepúlveda, Maria S; Xiao, Changhe; Cannon, Jason R; Freeman, Jennifer L

    2015-07-03

    Atrazine is an herbicide applied to agricultural crops and is indicated to be an endocrine disruptor. Atrazine is frequently found to contaminate potable water supplies above the maximum contaminant level of 3μg/L as defined by the U.S. Environmental Protection Agency. The developmental origin of adult disease hypothesis suggests that toxicant exposure during development can increase the risk of certain diseases during adulthood. However, the molecular mechanisms underlying disease progression are still unknown. In this study, zebrafish embryos were exposed to 0, 0.3, 3, or 30μg/L atrazine throughout embryogenesis. Larvae were then allowed to mature under normal laboratory conditions with no further chemical treatment until 7 days post fertilization (dpf) or adulthood and neurotransmitter analysis completed. No significant alterations in neurotransmitter levels was observed at 7dpf or in adult males, but a significant decrease in 5-hydroxyindoleacetic acid (5-HIAA) and serotonin turnover was seen in adult female brain tissue. Transcriptomic analysis was completed on adult female brain tissue to identify molecular pathways underlying the observed neurological alterations. Altered expression of 1928, 89, and 435 genes in the females exposed to 0.3, 3, or 30μg/L atrazine during embryogenesis were identified, respectively. There was a high level of overlap between the biological processes and molecular pathways in which the altered genes were associated. Moreover, a subset of genes was down regulated throughout the serotonergic pathway. These results provide support of the developmental origins of neurological alterations observed in adult female zebrafish exposed to atrazine during embryogenesis.

  8. [Effects of Kaixin San formulas on behavioristics and central monoamine neurotransmitters of chronic stress rats].

    PubMed

    Liu, Wan-wan; Xu, Lu; Dong, Xian-zhe; Tan, Xiao; Wang, Shi; Zhu, Wei-yu; Liu, Ping

    2015-06-01

    The efficacy of Chinese herbal formula in treating depression has been proved in many studies. In this study, six different Kaixin San formulas were compared to investigate their effects on central monoamine neurotransmitters of chronic stress rats and against depression based on their different components in plasma, in order to discuss the efficacy-comparability relationship and the possible efficacy mechanism. The classic isolation method and the chronic unpredictable mild stress (CUMS) depression model were combined to investigate the changes in contents in hippocampus and monoamine neurotransmitters (NE, DA, 5-HT) and the components of some formulas in plasma with HPLC and UPLC-Q-TOF-MSE methods. As a result, Dingzhi Xiaowan recorded in Essential Recipes for Emergent Use Worth A Thousand significantly increased the behavioral scores, NE and 5-HT contents in hippocampus and NE, DA and 5-HT contents in cortex, with the best anti-depressant effect. Dingzhi Xiaowan recorded in Complete Records of Ancient and Modern Medical Works showed a notable increase in sucrose preference and open field score in model rats, NE content in hippocampus and NE, DA and 5-HT contents in cortex, with a certain anti anti-depressant effect. Kaixin San recorded in Ishinpo showed remarkable rise in weight of model rats. NE content in hippocampus and DA content in cortex. Puxin Decoction recorded in A Supplement to Recipes Worth A Thousand Gold showed 5-HT content in hippocampus and DA content in cortex. Kaixin San recorded in Yimenfang only showed DA content in cortex. Kaixin Wan recorded in Essential Recipes for Emergent Use Worth A Thousand did not mention the antidepressant effect. According to the results, the formulas' different anti-depressant effects may be related to the different plasma components.

  9. The effects of avermectin on amino acid neurotransmitters and their receptors in the pigeon brain.

    PubMed

    Chen, Li-Jie; Sun, Bao-Hong; Cao, Ye; Yao, Hai-Dong; Qu, Jian-Ping; Liu, Ci; Xu, Shi-Wen; Li, Shu

    2014-03-01

    The objective of this study was to examine the effects of avermectin (AVM) on amino acid neurotransmitters and their receptors in the pigeon brain. Four groups two-month-old American king pigeons (n=20/group) were fed either a commercial diet or an AVM-supplemented diet (20mg/kg·diet, 40 mg/kg·diet, or 60 mg/kg·diet) for 30, 60, or 90 days. The contents of aspartic acid (ASP), glutamate (GLU), glycine (GLY), and γ-aminobutyric acid (GABA) in the brain tissues were determined using ultraviolet high-performance liquid chromatography (HPLC). The expression levels of the GLU and GABA receptor genes were analyzed using real-time quantitative polymerase chain reaction (qPCR). The results indicate that AVM exposure significantly enhances the contents of GABA, GLY, GLU, and ASP in the cerebrum, cerebellum, and optic lobe. In addition, AVM exposure increases the mRNA expression levels of γ-aminobutyric acid type A receptor (GABAAR), γ-aminobutyric acid type B receptor (GABABR), N-methyl-d-aspartate 1 receptor (NR1), N-methyl-d-aspartate 2A receptor (NR2A), and N-methyl-d-aspartate 2B receptor (NR2B) in a dose- and time-dependent manner. Moreover, we found that the most damaged organ was the cerebrum, followed by the cerebellum, and then the optic lobe. These results show that the AVM-induced neurotoxicity may be associated with its effects on amino acid neurotransmitters and their receptors. The information presented in this study will help supplement the available data for future AVM toxicity studies.

  10. Developmental origins of neurotransmitter and transcriptome alterations in adult female zebrafish exposed to atrazine during embryogenesis

    PubMed Central

    Wirbisky, Sara E.; Weber, Gregory J.; Sepúlveda, Maria S.; Xiao, Changhe; Cannon, Jason R.; Freeman, Jennifer L.

    2015-01-01

    Atrazine is an herbicide applied to agricultural crops and is indicated to be an endocrine disruptor. Atrazine is frequently found to contaminate potable water supplies above the maximum contaminant level of 3 µg/L as defined by the U. S. Environmental Protection Agency. The developmental origin of adult disease hypothesis suggests that toxicant exposure during development can increase the risk of certain diseases during adulthood. However, the molecular mechanisms underlying disease progression are still unknown. In this study, zebrafish embryos were exposed to 0, 0.3, 3, or 30 µg/L atrazine throughout embryogenesis. Larvae were then allowed to mature under normal laboratory conditions with no further chemical treatment until 7 days post fertilization (dpf) or adulthood and neurotransmitter analysis completed. No significant alterations in neurotransmitter levels was observed at 7 dpf or in adult males, but a significant decrease in 5-Hydroxyindoleacetic acid (5-HIAA) and serotonin turnover was seen in adult female brain tissue. Transcriptomic analysis was completed on adult female brain tissue to identify molecular pathways underlying the observed neurological alterations. Altered expression of 1853, 84, and 419 genes in the females exposed to 0.3, 3, or 30 µg/L atrazine during embryogenesis were identified, respectively. There was a high level of overlap between the biological processes and molecular pathways in which the altered genes were associated. Moreover, a subset of genes was down regulated throughout the serotonergic pathway. These results provide support of the developmental origins of neurological alterations observed in adult female zebrafish exposed to atrazine during embryogenesis. PMID:25929836

  11. Neurotransmitters regulating acid secretion in the proventriculus of the Houbara bustard (Chlamydotis undulata): a morphological viewpoint.

    PubMed

    Mensah-Brown, E P; Lawrence, P A

    2001-05-01

    Endocrine cells containing somatostatin (Som), gastrin-releasing peptide (GRP), and neuronal nitric oxide synthase (nNOS) and nerve fibers containing choline acetyl transferase (ChAT), tyrosine hydroxylase (TH), galanin (Gal), substance P (SP), and vasoactive intestinal polypeptide (VIP) were immunolocalized in the proventriculus of the Houbara bustard, Chlamydotis undulata. While GRP-immunoreactive (GRP-IR) cells occur in the inner zone, somatostatin (Som-IR) and polyclonal nNOS (nNOS-IR) immunoreactive cells were localized mainly in the peripheral zone of submucosal glands. GRP-IR, Som-IR, and nNOS-IR cells were occasionally observed in the walls of the gastric glands. Endocrine cells are of the closed variety and usually possess apical processes extending along the basal surfaces of adjacent nonreactive cells. Ultrastructural features of these cells are typical. ChAT, Gal, SP, VIP, and TH were immunolocalized in nerve fibers and terminals in the walls of arterioles and capillaries at the periphery of submucosal glands. Immunoreactivity to monoclonal nNOS occurred mainly in neuronal cell bodies in ganglia located around the submucosal glands. ChAT and TH immunoreactive cell bodies were also occasionally seen around the submucosal glands in the peripheral region. Immunoreactivity to Gal, SP, and VIP, but not ChAT or TH, was discernible around the walls of gastric glands. It was concluded that the distribution of neurotransmitters in neuronal structures is similar, but that of the endocrine cells varies from that of some avian species. The roles of these neurotransmitters in the regulation of acid secretion are discussed.

  12. Near-infrared surface-enhanced Raman scattering (NIR-SERS) of neurotransmitters in colloidal silver solutions

    NASA Astrophysics Data System (ADS)

    Kneipp, Katrin; Wang, Yang; Dasari, Ramachandra R.; Feld, Michael S.

    1995-03-01

    NIR-SERS spectra are measured for the neurotransmitters dopamine and norepinephrine at concentrations as low as 5 × 10 -9 M in colloidal silver solutions with accumulation times as short as 25 ms. The detection range and acquisition time are on the order of physiologically relevant concentrations and the time scale of neuronal processes, respectively. The spectra are obtained using a CCD detection system, dye laser at 830 nm for excitation, fiber optic probe and high throughput spectrograph. Mixtures containing the two neurotransmitters are used to demonstrate the capability of extracting quantitative information from SERS spectra. Albumin added to the sample up to 0.5% concentration does not show any influence on the SERS spectra of the neurotransmitters in the silver colloidal solutions. The results demonstrate the potential of NIR-SERS in probing dopamine and norepinephrine with high sensitivity and specificity. They also suggest that NIR-SERS from colloidal silver solution can be a powerful tool for the study of neurotransmitters in brain extracts and dialysates.

  13. Direct Visualization of Neurotransmitters in Rat Brain Slices by Desorption Electrospray Ionization Mass Spectrometry Imaging (DESI - MS)

    NASA Astrophysics Data System (ADS)

    Fernandes, Anna Maria A. P.; Vendramini, Pedro H.; Galaverna, Renan; Schwab, Nicolas V.; Alberici, Luciane C.; Augusti, Rodinei; Castilho, Roger F.; Eberlin, Marcos N.

    2016-12-01

    Mass spectrometry imaging (MSI) of neurotransmitters has so far been mainly performed by matrix-assisted laser desorption/ionization (MALDI) where derivatization reagents, deuterated matrix and/or high resolution, or tandem MS have been applied to circumvent problems with interfering ion peaks from matrix and from isobaric species. We herein describe the application of desorption electrospray ionization mass spectrometry imaging (DESI)-MSI in rat brain coronal and sagittal slices for direct spatial monitoring of neurotransmitters and choline with no need of derivatization reagents and/or deuterated materials. The amino acids γ-aminobutyric (GABA), glutamate, aspartate, serine, as well as acetylcholine, dopamine, and choline were successfully imaged using a commercial DESI source coupled to a hybrid quadrupole-Orbitrap mass spectrometer. The spatial distribution of the analyzed compounds in different brain regions was determined. We conclude that the ambient matrix-free DESI-MSI is suitable for neurotransmitter imaging and could be applied in studies that involve evaluation of imbalances in neurotransmitters levels.

  14. Fetal growth-retardation and brain-sparing by malnutrition are associated to changes in neurotransmitters profile.

    PubMed

    García-Contreras, C; Valent, D; Vázquez-Gómez, M; Arroyo, L; Isabel, B; Astiz, S; Bassols, A; Gonzalez-Bulnes, A

    2017-04-01

    The present study assesses possible changes in the levels of different neurotransmitters (catecholamines and indoleamines) in fetuses affected by nutrient shortage. Hence, we determined the concentration of catecholamines and indoleamines at the hypothalamus of 56 swine fetuses obtained at both 70 and 90days of pregnancy (n=33 and 23 fetuses, respectively). The degree of fetal development and the fetal sex affected the neurotransmitters profile at both stages. At Day 70, there were found higher mean concentrations of l-DOPA in both female and male fetuses with severe IUGR; male fetuses with severe IUGR also showed higher concentrations of TRP than normal male littermates. At Day 90 of pregnancy, the differences between sexes were more evident. There were no significant effects from either severe IUGR on the neurotransmitter profile in male fetuses. However, in the females, a lower body-weight was related to lower concentrations of l-DOPA and TRP and those female fetuses affected by severe IUGR evidenced lower HVA concentration. In conclusion, the fetal synthesis and use of neurotransmitters increase with time of pregnancy but, in case of IUGR, both catecholamines and indoleamines pathways are affected by sex-related effects.

  15. A Preliminary Study of Gene Polymorphisms Involved in the Neurotransmitters Metabolism of a Homogeneous Spanish Autistic Group

    ERIC Educational Resources Information Center

    Calahorro, Fernando; Alejandre, Encarna; Anaya, Nuria; Guijarro, Teresa; Sanz, Yolanza; Romero, Auxiliadora; Tienda, Pilar; Burgos, Rafael; Gay, Eudoxia; Sanchez, Vicente; Ruiz-Rubio, Manuel

    2009-01-01

    Twin studies have shown a strong genetic component for autism. Neurotransmitters, such as serotonin and catecholamines, have been suggested to play a role in the disease since they have an essential function in synaptogenesis and brain development. In this preliminary study, polymorphism of genes implicated in the serotonergic and dopaminergic…

  16. Direct Visualization of Neurotransmitters in Rat Brain Slices by Desorption Electrospray Ionization Mass Spectrometry Imaging (DESI - MS).

    PubMed

    Fernandes, Anna Maria A P; Vendramini, Pedro H; Galaverna, Renan; Schwab, Nicolas V; Alberici, Luciane C; Augusti, Rodinei; Castilho, Roger F; Eberlin, Marcos N

    2016-12-01

    Mass spectrometry imaging (MSI) of neurotransmitters has so far been mainly performed by matrix-assisted laser desorption/ionization (MALDI) where derivatization reagents, deuterated matrix and/or high resolution, or tandem MS have been applied to circumvent problems with interfering ion peaks from matrix and from isobaric species. We herein describe the application of desorption electrospray ionization mass spectrometry imaging (DESI)-MSI in rat brain coronal and sagittal slices for direct spatial monitoring of neurotransmitters and choline with no need of derivatization reagents and/or deuterated materials. The amino acids γ-aminobutyric (GABA), glutamate, aspartate, serine, as well as acetylcholine, dopamine, and choline were successfully imaged using a commercial DESI source coupled to a hybrid quadrupole-Orbitrap mass spectrometer. The spatial distribution of the analyzed compounds in different brain regions was determined. We conclude that the ambient matrix-free DESI-MSI is suitable for neurotransmitter imaging and could be applied in studies that involve evaluation of imbalances in neurotransmitters levels. Graphical Abstract ᅟ.

  17. Pharmacology of iron transport.

    PubMed

    Byrne, Shaina L; Krishnamurthy, Divya; Wessling-Resnick, Marianne

    2013-01-01

    Elucidating the molecular basis for the regulation of iron uptake, storage, and distribution is necessary to understand iron homeostasis. Pharmacological tools are emerging to identify and distinguish among different iron transport pathways. Stimulatory or inhibitory small molecules with effects on iron uptake can help characterize the mechanistic elements of iron transport and the roles of the transporters involved in these processes. In particular, iron chelators can serve as potential pharmacological tools to alleviate diseases of iron overload. This review focuses on the pharmacology of iron transport, introducing iron transport membrane proteins and known inhibitors.

  18. Pharmacology of Iron Transport

    PubMed Central

    Byrne, Shaina L.; Krishnamurthy, Divya; Wessling-Resnick, Marianne

    2013-01-01

    Elucidating the molecular basis for the regulation of iron uptake, storage, and distribution is necessary to understand iron homeostasis. Pharmacological tools are emerging to identify and distinguish among different iron transport pathways. Stimulatory or inhibitory small molecules with effects on iron uptake can help characterize the mechanistic elements of iron transport and the roles of the transporters involved in these processes. In particular, iron chelators can serve as potential pharmacological tools to alleviate diseases of iron overload. This review focuses on the pharmacology of iron transport, introducing iron transport membrane proteins and known inhibitors. PMID:23020294

  19. Molecular basis for substrate discrimination by glycine transporters.

    PubMed

    Vandenberg, Robert J; Shaddick, Kim; Ju, Pengchu

    2007-05-11

    Glycine is an inhibitory neurotransmitter in the spinal cord and brain stem, where it acts on strychnine-sensitive glycine receptors, and is also an excitatory neurotransmitter throughout the brain and spinal cord, where it acts on the N-methyl-d-aspartate family of receptors. There are two Na(+)/Cl(-)-dependent glycine transporters, GLYT1 and GLYT2, which control extracellular glycine concentrations and these transporters show differences in substrate selectivity and blocker sensitivity. A bacterial Na(+)-dependent leucine transporter (LeuT(Aa)) has recently been crystallized and its structure determined. When the amino acid residues within the leucine binding site of LeuT(Aa) are aligned with residues of the two glycine transporters there are a number of identical residues and also some key differences. In this report, we demonstrate that the LeuT(Aa) structure represents a good working model of the Na(+)/Cl(-)-dependent neurotransmitters and that differences in substrate selectivity can be attributed to a single difference of a glycine residue in transmembrane domain 6 of GLYT1 for a serine residue at the corresponding position of GLYT2.

  20. Focus Curriculum Manual; A Focus Dissemination Project.

    ERIC Educational Resources Information Center

    Human Resource Associates, Inc., Hastings, Minn.

    This training manual is for use in preparing staff members to use the Focus Model, which is a "school within a school" for disaffected high school students. The material is designed to be used as a resource aid following participation in an in-service workshop. Information is presented to help implement a contracting system to establish…

  1. Metabolism of acetyl-L-carnitine for energy and neurotransmitter synthesis in the immature rat brain.

    PubMed

    Scafidi, Susanna; Fiskum, Gary; Lindauer, Steven L; Bamford, Penelope; Shi, Da; Hopkins, Irene; McKenna, Mary C

    2010-08-01

    Acetyl-L-carnitine (ALCAR) is an endogenous metabolic intermediate that facilitates the influx and efflux of acetyl groups across the mitochondrial inner membrane. Exogenously administered ALCAR has been used as a nutritional supplement and also as an experimental drug with reported neuroprotective properties and effects on brain metabolism. The aim of this study was to determine oxidative metabolism of ALCAR in the immature rat forebrain. Metabolism was studied in 21-22 day-old rat brain at 15, 60 and 120 min after an intraperitoneal injection of [2-(13)C]acetyl-L-carnitine. The amount, pattern, and fractional enrichment of (13)C-labeled metabolites were determined by ex vivo(13)C-NMR spectroscopy. Metabolism of the acetyl moiety from [2-(13)C]ALCAR via the tricarboxylic acid cycle led to incorporation of label into the C4, C3 and C2 positions of glutamate (GLU), glutamine (GLN) and GABA. Labeling patterns indicated that [2-(13)C]ALCAR was metabolized by both neurons and glia; however, the percent enrichment was higher in GLN and GABA than in GLU, demonstrating high metabolism in astrocytes and GABAergic neurons. Incorporation of label into the C3 position of alanine, both C3 and C2 positions of lactate, and the C1 and C5 positions of glutamate and glutamine demonstrated that [2-(13)C]ALCAR was actively metabolized via the pyruvate recycling pathway. The enrichment of metabolites with (13)C from metabolism of ALCAR was highest in alanine C3 (11%) and lactate C3 (10%), with considerable enrichment in GABA C4 (8%), GLN C3 (approximately 4%) and GLN C5 (5%). Overall, our (13)C-NMR studies reveal that the acetyl moiety of ALCAR is metabolized for energy in both astrocytes and neurons and the label incorporated into the neurotransmitters glutamate and GABA. Cycling ratios showed prolonged cycling of carbon from the acetyl moiety of ALCAR in the tricarboxylic acid cycle. Labeling of compounds formed from metabolism of [2-(13)C]ALCAR via the pyruvate recycling pathway

  2. Rotating apparatus for isoelectric focusing

    NASA Technical Reports Server (NTRS)

    Bier, Milan (Inventor)

    1986-01-01

    This disclosure is directed to an isoelectric focusing apparatus, wherein stabilization of the fluid containing the isolated proteins is achieved by carrying out the separation in a rotating cylinder with the separation cavity of the cylinder being segmented by means of filter elements. The filter elements are constituted of a material offering some degree of resistance to fluid convection, but allowing relatively free and unhindered passage of current and transport of proteins. The combined effect of segmentation and rotation has been found to be superior to either segmentation or rotation alone in maintaining the stability of the migrated fractions.

  3. Focus Intonation in Bengali

    ERIC Educational Resources Information Center

    Hasan, Md. Kamrul

    2015-01-01

    This work attempts to investigate the role of prosody in the syntax of focus in Bangla. The aim of this study is to show the intonation pattern of Bangla in emphasis and focus. In order to do that, the author has looked at the pattern of focus without-i/o as well as with the same. Do they really pose any different focus intonation pattern from…

  4. Bovine neuronal vesicular glutamate transporter activity is inhibited by ergovaline and other ergopeptines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    L-Glutamate (Glu) is the major excitatory neurotransmitter responsible for neurotransmission in the vertebrate central nervous system, including the gastrointestinal tract (GIT) of cattle. Vesicular Glu transporters VGLUT1 and VGLUT2 concentrate (50 mM) Glu (Km = 1 to 4 mM) into synaptic vesicles (S...

  5. Alternating phase focused linacs

    DOEpatents

    Swenson, Donald A.

    1980-01-01

    A heavy particle linear accelerator employing rf fields for transverse and ongitudinal focusing as well as acceleration. Drift tube length and gap positions in a standing wave drift tube loaded structure are arranged so that particles are subject to acceleration and succession of focusing and defocusing forces which contain the beam without additional magnetic or electric focusing fields.

  6. Membrane Transporters: Structure, Function and Targets for Drug Design

    NASA Astrophysics Data System (ADS)

    Ravna, Aina W.; Sager, Georg; Dahl, Svein G.; Sylte, Ingebrigt

    Current therapeutic drugs act on four main types of molecular targets: enzymes, receptors, ion channels and transporters, among which a major part (60-70%) are membrane proteins. This review discusses the molecular structures and potential impact of membrane transporter proteins on new drug discovery. The three-dimensional (3D) molecular structure of a protein contains information about the active site and possible ligand binding, and about evolutionary relationships within the protein family. Transporters have a recognition site for a particular substrate, which may be used as a target for drugs inhibiting the transporter or acting as a false substrate. Three groups of transporters have particular interest as drug targets: the major facilitator superfamily, which includes almost 4000 different proteins transporting sugars, polyols, drugs, neurotransmitters, metabolites, amino acids, peptides, organic and inorganic anions and many other substrates; the ATP-binding cassette superfamily, which plays an important role in multidrug resistance in cancer chemotherapy; and the neurotransmitter:sodium symporter family, which includes the molecular targets for some of the most widely used psychotropic drugs. Recent technical advances have increased the number of known 3D structures of membrane transporters, and demonstrated that they form a divergent group of proteins with large conformational flexibility which facilitates transport of the substrate.

  7. Schizophrenia-Associated MIR204 Regulates Noncoding RNAs and Affects Neurotransmitter and Ion Channel Gene Sets

    PubMed Central

    Cammaerts, Sophia; Strazisar, Mojca; Smets, Bart; Weckhuysen, Sarah; Nordin, Annelie; De Jonghe, Peter; Adolfsson, Rolf; De Rijk, Peter; Del Favero, Jurgen

    2015-01-01

    As regulators of gene expression, microRNAs (miRNAs) are likely to play an important role in the development of disease. In this study we present a large-scale strategy to identify miRNAs with a role in the regulation of neuronal processes. Thereby we found variant rs7861254 located near the MIR204 gene to be significantly associated with schizophrenia. This variant resulted in reduced expression of miR-204 in neuronal-like SH-SY5Y cells. Analysis of the consequences of the altered miR-204 expression on the transcriptome of these cells uncovered a new mode of action for miR-204, being the regulation of noncoding RNAs (ncRNAs), including several miRNAs, such as MIR296. Furthermore, pathway analysis showed downstream effects of miR-204 on neurotransmitter and ion channel related gene sets, potentially mediated by miRNAs regulated through miR-204. PMID:26714269

  8. Role of putative neurotransmitters in the central gastric antisecretory effect of prostaglandin E2 in rats.

    PubMed Central

    Puurunen, J.

    1985-01-01

    The role of putative neurotransmitters of the central nervous system in the central gastric antisecretory effect of prostaglandin E2 (PGE2) was investigated in pylorus-ligated rats. Pretreatment of the rats with an intracerebroventricular (i.c.v.) injection of 6-hydroxydopamine (6-OHDA) prevented the antisecretory effect of the i.c.v. administration of PGE2, whereas pretreatment with 5,6-dihydroxytryptamine (5,6-DHT) plus p-chlorophenylalanine (PCPA) had no effect. I.c.v.-administered phentolamine and idazoxan antagonized the inhibition of gastric secretion induced by i.c.v. PGE2, whereas prazosin, propranolol and sulpiride injected via the same route were ineffective. Diphenhydramine, cimetidine, naloxone and theophylline, all administered i.c.v., did not modify the antisecretory effect of i.c.v. PGE2. The results suggest that an activation of alpha 2-adrenoceptors in the brain is involved in the central gastric antisecretory effect of PGE2, whereas neither central 5-hydroxytryptamine receptors, alpha 1- or beta-adrenoceptors, D2-dopamine receptors, histamine or opioid receptors nor adenosine seem to play any role here. PMID:2862940

  9. Sex hormones affect neurotransmitters and shape the adult female brain during hormonal transition periods

    PubMed Central

    Barth, Claudia; Villringer, Arno; Sacher, Julia

    2015-01-01

    Sex hormones have been implicated in neurite outgrowth, synaptogenesis, dendritic branching, myelination and other important mechanisms of neural plasticity. Here we review the evidence from animal experiments and human studies reporting interactions between sex hormones and the dominant neurotransmitters, such as serotonin, dopamine, GABA and glutamate. We provide an overview of accumulating data during physiological and pathological conditions and discuss currently conceptualized theories on how sex hormones potentially trigger neuroplasticity changes through these four neurochemical systems. Many brain regions have been demonstrated to express high densities for estrogen- and progesterone receptors, such as the amygdala, the hypothalamus, and the hippocampus. As the hippocampus is of particular relevance in the context of mediating structural plasticity in the adult brain, we put particular emphasis on what evidence could be gathered thus far that links differences in behavior, neurochemical patterns and hippocampal structure to a changing hormonal environment. Finally, we discuss how physiologically occurring hormonal transition periods in humans can be used to model how changes in sex hormones influence functional connectivity, neurotransmission and brain structure in vivo. PMID:25750611

  10. Determining Ca2+-sensor binding time and its variability in evoked neurotransmitter release

    PubMed Central

    Yoon, Ava Chomee; Kathpalia, Vinnie; D/Silva, Sahana; Cimenser, Aylin; Hua, Shao-Ying

    2008-01-01

    The speed and reliability of neuronal reactions are important factors for proper functioning of the nervous system. To understand how organisms use protein molecules to carry out very fast biological actions, we quantified single-molecule reaction time and its variability in synaptic transmission. From the synaptic delay of crayfish neuromuscular synapses the time for a few Ca2+ ions to bind with their sensors in evoked neurotransmitter release was estimated. In standard crayfish saline at room temperature, the average Ca2+ binding time was 0.12 ms for the first evoked quanta. At elevated extracellular Ca2+ concentrations this binding time reached a limit due to saturation of Ca2+ influx. Analysis of the synaptic delay variance at various Ca2+ concentrations revealed that the variability of the Ca2+-sensor binding time is the major source of the temporal variability of synaptic transmission, and that the Ca2+-independent molecular reactions after Ca2+ influx were less stochastic. The results provide insights into how organisms maximize reaction speed and reliability. PMID:18063666

  11. Amnesia produced by altered release of neurotransmitters after intraamygdala injections of a protein synthesis inhibitor

    PubMed Central

    Canal, Clinton E.; Chang, Qing; Gold, Paul E.

    2007-01-01

    Amnesia produced by protein synthesis inhibitors such as anisomycin provides major support for the prevalent view that the formation of long-lasting memories requires de novo protein synthesis. However, inhibition of protein synthesis might disrupt other neural functions to interfere with memory formation. Intraamygdala injections of anisomycin before inhibitory avoidance training impaired memory in rats tested 48 h later. Release of norepinephrine (NE), dopamine (DA), and serotonin, measured at the site of anisomycin infusions, increased quickly by ≈1,000–17,000%, far above the levels seen under normal conditions. NE and DA release later decreased far below baseline for several hours before recovering at 48 h. Intraamygdala injections of a β-adrenergic receptor antagonist or agonist, each timed to blunt effects of increases and decreases in NE release after anisomycin, attenuated anisomycin-induced amnesia. In addition, similar to the effects on memory seen with anisomycin, intraamygdala injections of a high dose of NE before training impaired memory tested at 48 h after training. These findings suggest that altered release of neurotransmitters may mediate amnesia produced by anisomycin and, further, raise important questions about the empirical bases for many molecular theories of memory formation. PMID:17640910

  12. Nigella sativa L. Seed Extract Modulates the Neurotransmitter Amino Acids Release in Cultured Neurons In Vitro

    PubMed Central

    El-Naggar, Tarek; Gómez-Serranillos, María Pilar; Palomino, Olga María; Arce, Carmen; Carretero, María Emilia

    2010-01-01

    Nigella sativa L. (NS) has been used for medicinal purposes since ancient times. This study aimed to investigate the cytotoxicity of NS dry methanolic extract on cultured cortical neurons and its influence on neurotransmitter release, as well as the presence of excitatory (glutamate and aspartate) and inhibitory amino acids (gamma-aminobutyric acid—GABA—and glycine) in NS extract. Cultured rat cortical neurons were exposed to different times and concentrations of NS dry methanolic extract and cell viability was then determined by a quantitative colorimetric method. NS did not induce any toxicity. The secretion of different amino acids was studied in primary cultured cortical neurons by high-performance liquid chromatography (HPLC) using a derivation before injection with dansyl chloride. NS modulated amino acid release in cultured neurons; GABA was significantly increased whereas secretion of glutamate, aspartate, and glycine were decreased. The in vitro findings support the hypothesis that the sedative and depressive effects of NS observed in vivo could be based on changes of inhibitory/excitatory amino acids levels. PMID:20625485

  13. Amnesia produced by altered release of neurotransmitters after intraamygdala injections of a protein synthesis inhibitor.

    PubMed

    Canal, Clinton E; Chang, Qing; Gold, Paul E

    2007-07-24

    Amnesia produced by protein synthesis inhibitors such as anisomycin provides major support for the prevalent view that the formation of long-lasting memories requires de novo protein synthesis. However, inhibition of protein synthesis might disrupt other neural functions to interfere with memory formation. Intraamygdala injections of anisomycin before inhibitory avoidance training impaired memory in rats tested 48 h later. Release of norepinephrine (NE), dopamine (DA), and serotonin, measured at the site of anisomycin infusions, increased quickly by approximately 1,000-17,000%, far above the levels seen under normal conditions. NE and DA release later decreased far below baseline for several hours before recovering at 48 h. Intraamygdala injections of a beta-adrenergic receptor antagonist or agonist, each timed to blunt effects of increases and decreases in NE release after anisomycin, attenuated anisomycin-induced amnesia. In addition, similar to the effects on memory seen with anisomycin, intraamygdala injections of a high dose of NE before training impaired memory tested at 48 h after training. These findings suggest that altered release of neurotransmitters may mediate amnesia produced by anisomycin and, further, raise important questions about the empirical bases for many molecular theories of memory formation.

  14. Comparative neurotransmitter reuptake and anticholinergic potencies of the 8-hydroxy metabolites of clomipramine.

    PubMed

    Núñez, R; Perel, J M

    1995-01-01

    We hypothesize that 8-hydroxy-clomipramine (8-OH-CMI), the major hydroxy metabolite of clomipramine (CMI), may have antidepressant properties with less anticholinergic potency than CMI. We compared the potencies of 8-OH-CMI and CMI for inhibition of serotonin and norepinephrine reuptake and the potencies of these compounds for blockade of muscarinic receptors. We also compared the antimuscarinic potencies of desmethylclomipramine (DCMI) and 8-hydroxy-desmethylclomipramine (8-OH-DCMI). We found that 8-OH-CMI inhibits the uptake of serotonin and norepinephrine to the same extent as CMI and that 8-OH-CMI has far less antimuscarinic potency than CMI. We also found that 8-OH-DCMI has about one-tenth the antimuscarinic potency of DCMI. Since the therapeutic efficacy of CMI may be related to its effect on the reuptake of neurotransmitters, and since the extent of clinical anticholinergic effects of tricyclic antidepressants has been shown to be related to their in vitro antimuscarinic potencies, these results raise the possibility that 8-OH-CMI may be an analogue of CMI with fewer anticholinergic side effects than the parent compound.

  15. Activity-dependent, homeostatic regulation of neurotransmitter release from auditory nerve fibers

    PubMed Central

    Ngodup, Tenzin; Goetz, Jack A.; McGuire, Brian C.; Sun, Wei; Lauer, Amanda M.; Xu-Friedman, Matthew A.

    2015-01-01

    Information processing in the brain requires reliable synaptic transmission. High reliability at specialized auditory nerve synapses in the cochlear nucleus results from many release sites (N), high probability of neurotransmitter release (Pr), and large quantal size (Q). However, high Pr also causes auditory nerve synapses to depress strongly when activated at normal rates for a prolonged period, which reduces fidelity. We studied how synapses are influenced by prolonged activity by exposing mice to constant, nondamaging noise and found that auditory nerve synapses changed to facilitating, reflecting low Pr. For mice returned to quiet, synapses recovered to normal depression, suggesting that these changes are a homeostatic response to activity. Two additional properties, Q and average excitatory postsynaptic current (EPSC) amplitude, were unaffected by noise rearing, suggesting that the number of release sites (N) must increase to compensate for decreased Pr. These changes in N and Pr were confirmed physiologically using the integration method. Furthermore, consistent with increased N, endbulbs in noise-reared animals had larger VGlut1-positive puncta, larger profiles in electron micrographs, and more release sites per profile. In current-clamp recordings, noise-reared BCs had greater spike fidelity even during high rates of synaptic activity. Thus, auditory nerve synapses regulate excitability through an activity-dependent, homeostatic mechanism, which could have major effects on all downstream processing. Our results also suggest that noise-exposed bushy cells would remain hyperexcitable for a period after returning to normal quiet conditions, which could have perceptual consequences. PMID:25944933

  16. Functional roles of complexin in neurotransmitter release at ribbon synapses of mouse retinal bipolar neurons.

    PubMed

    Vaithianathan, Thirumalini; Henry, Diane; Akmentin, Wendy; Matthews, Gary

    2015-03-04

    Ribbon synapses of photoreceptor cells and bipolar neurons in the retina signal graded changes in light intensity via sustained release of neurotransmitter. One molecular specialization of retinal ribbon synapses is the expression of complexin protein subtypes Cplx3 and Cplx4, whereas conventional synapses express Cplx1 and Cplx2. Because complexins bind to the molecular machinery for synaptic vesicle fusion (the SNARE complex) and modulate transmitter release at conventional synapses, we examined the roles of ribbon-specific complexin in regulating release at ribbon synapses of ON bipolar neurons from mouse retina. To interfere acutely with the interaction of native complexins with the SNARE complex, a peptide consisting of the highly conserved SNARE-binding domain of Cplx3 was introduced via a whole-cell patch pipette placed directly on the synaptic terminal, and vesicle fusion was monitored using capacitance measurements and FM-dye destaining. The inhibitory peptide, but not control peptides, increased spontaneous synaptic vesicle fusion, partially depleted reserve synaptic vesicles, and reduced fusion triggered by opening voltage-gated calcium channels under voltage clamp, without affecting the number of synaptic vesicles associated with ribbons, as revealed by electron microscopy of recorded terminals. The results are consistent with a dual role for ribbon-specific complexin, acting as a brake on the SNARE complex to prevent spontaneous fusion in the absence of calcium influx, while at the same time facilitating release evoked by depolarization.

  17. Stabilization of spontaneous neurotransmitter release at ribbon synapses by ribbon-specific subtypes of complexin.

    PubMed

    Vaithianathan, Thirumalini; Zanazzi, George; Henry, Diane; Akmentin, Wendy; Matthews, Gary

    2013-05-08

    Ribbon synapses of tonically releasing sensory neurons must provide a large pool of releasable vesicles for sustained release, while minimizing spontaneous release in the absence of stimulation. Complexins are presynaptic proteins that may accomplish this dual task at conventional synapses by interacting with the molecular machinery of synaptic vesicle fusion at the active zone to retard spontaneous vesicle exocytosis yet facilitate release evoked by depolarization. However, ribbon synapses of photoreceptor cells and bipolar neurons in the retina express distinct complexin subtypes, perhaps reflecting the special requirements of these synapses for tonic release. To investigate the role of ribbon-specific complexins in transmitter release, we combined presynaptic voltage clamp, fluorescence imaging, electron microscopy, and behavioral assays of photoreceptive function in zebrafish. Acute interference with complexin function using a peptide derived from the SNARE-binding domain increased spontaneous synaptic vesicle fusion at ribbon synapses of retinal bipolar neurons without affecting release triggered by depolarization. Knockdown of complexin by injection of an antisense morpholino into zebrafish embryos prevented photoreceptor-driven migration of pigment in skin melanophores and caused the pigment distribution to remain in the dark-adapted state even when embryos were exposed to light. This suggests that loss of complexin function elevated spontaneous release in illuminated photoreceptors sufficiently to mimic the higher release rate normally associated with darkness, thus interfering with visual signaling. We conclude that visual system-specific complexins are required for proper illumination-dependent modulation of the rate of neurotransmitter release at visual system ribbon synapses.

  18. Tributyltin exposure influences predatory behavior, neurotransmitter content and receptor expression in Sebastiscus marmoratus.

    PubMed

    Yu, Ang; Wang, Xinli; Zuo, Zhenghong; Cai, Jiali; Wang, Chonggang

    2013-03-15

    Tributyltin (TBT) is a ubiquitous marine contaminant due to its extensive use as a biocide, fungicide and antifouling agent. However, the neurotoxic effect of TBT has not been extensively studied, especially in marine fish. This study was conducted to investigate the effects of TBT (10, 100 and 1000 ng/L) on the predatory behavior of Sebastiscus marmoratus and to look into the mechanism involved. The results showed that TBT exposure depressed predatory activity after 50 days exposure. Dopamine levels in the fish brains increased in a dose-dependent manner, while 5-hydroxytryptamine and norepinephrine levels decreased significantly in the TBT exposure group compared to the control. The mRNA levels of dopamine receptors, which have functions such as cognition, motor activity, motivation and reward, mood, attention and learning, were significantly down-regulated by TBT exposure. Although the levels of amino acid neurotransmitters, including glutamate, did not show marked alteration, the expression of the glutamatergic signaling pathway such as N-methyl-D-aspartate receptors, a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor, calmodulin, Ca(2+)/calmodulin-dependent protein kinases-II and cyclic adenosine monophosphate responsive element binding protein, was significantly reduced by TBT exposure, which indicated that central nerve activities were in a state of depression, thus affecting the predatory activities of the fish.

  19. Stretched graphene tented by polycaprolactone and polypyrrole net-bracket for neurotransmitter detection

    NASA Astrophysics Data System (ADS)

    Wang, Zhenzhen; Ying, Ye; Li, Li; Xu, Ting; Wu, Yiping; Guo, Xiaoyu; Wang, Feng; Shen, Haojie; Wen, Ying; Yang, Haifeng

    2017-02-01

    A net-bracket built out from the core@shell structure of chemically oxidized polypyrrole (PPy) coated electrospun polycaprolactone (PCL) nanofibers, and the following surface modification of a thin layer of positively charged poly(dimethyl diallyl ammonium chloride) (PDDA) has been applied for stretching the reduced graphene oxide (RGO) sheets to some extent with the electrochemical deposition method. The as-formed RGO/PDDA/PCL@PPy nanocomposites were investigated by using scanning electron microscopy, transmission electron microscope, X-ray diffraction and Raman spectroscopy. The graphene tented by the net-bracket showed remarkable electrocatalytic properties in detecting the neurotransmitter dopamine (DA). Low detection limit of 0.34 μM (S/N = 3) with the wide linear detection range from 4 μM to 690 μM was obtained. The successful determination of DA in real urine samples and DA injection were achieved. Such attractive fabrication strategy can be extended to make other graphene sheet-based sensors.

  20. Mechanical tension contributes to clustering of neurotransmitter vesicles at presynaptic terminals

    PubMed Central

    Siechen, Scott; Yang, Shengyuan; Chiba, Akira; Saif, Taher

    2009-01-01

    Memory and learning in animals are mediated by neurotransmitters that are released from vesicles clustered at the synapse. As a synapse is used more frequently, its neurotransmission efficiency increases, partly because of increased vesicle clustering in the presynaptic neuron. Vesicle clustering has been believed to result primarily from biochemical signaling processes that require the connectivity of the presynaptic terminal with the cell body, the central nervous system, and the postsynaptic cell. Our in vivo experiments on the embryonic Drosophila nervous system show that vesicle clustering at the neuromuscular presynaptic terminal depends on mechanical tension within the axons. Vesicle clustering vanishes upon severing the axon from the cell body, but is restored when mechanical tension is applied to the severed end of the axon. Clustering increases when intact axons are stretched mechanically by pulling the postsynaptic muscle. Using micro mechanical force sensors, we find that embryonic axons that have formed neuromuscular junctions maintain a rest tension of ≈1 nanonewton. If the rest tension is perturbed mechanically, axons restore the rest tension either by relaxing or by contracting over a period of ≈15 min. Our results suggest that neuromuscular synapses employ mechanical tension as a signal to modulate vesicle accumulation and synaptic plasticity. PMID:19620718

  1. Can Nanofluidic Chemical Release Enable Fast, High Resolution Neurotransmitter-Based Neurostimulation?

    PubMed Central

    Jones, Peter D.; Stelzle, Martin

    2016-01-01

    Artificial chemical stimulation could provide improvements over electrical neurostimulation. Physiological neurotransmission between neurons relies on the nanoscale release and propagation of specific chemical signals to spatially-localized receptors. Current knowledge of nanoscale fluid dynamics and nanofluidic technology allows us to envision artificial mechanisms to achieve fast, high resolution neurotransmitter release. Substantial technological development is required to reach this goal. Nanofluidic technology—rather than microfluidic—will be necessary; this should come as no surprise given the nanofluidic nature of neurotransmission. This perspective reviews the state of the art of high resolution electrical neuroprostheses and their anticipated limitations. Chemical release rates from nanopores are compared to rates achieved at synapses and with iontophoresis. A review of microfluidic technology justifies the analysis that microfluidic control of chemical release would be insufficient. Novel nanofluidic mechanisms are discussed, and we propose that hydrophobic gating may allow control of chemical release suitable for mimicking neurotransmission. The limited understanding of hydrophobic gating in artificial nanopores and the challenges of fabrication and large-scale integration of nanofluidic components are emphasized. Development of suitable nanofluidic technology will require dedicated, long-term efforts over many years. PMID:27065794

  2. Effects of soluble β-amyloid on the release of neurotransmitters from rat brain synaptosomes

    PubMed Central

    Olivero, Guendalina; Grilli, Massimo; Chen, Jiayang; Preda, Stefania; Mura, Elisa; Govoni, Stefano; Marchi, Mario

    2014-01-01

    Contradictory results have been reported on the interaction of beta-amyloid (Aβ) with cholinergic receptors. The present paper investigates the modulatory effect of Aβ1-40 on the neurotransmitter release evoked by nicotinic (nAChRs) and muscarinic (mAChRs) receptors. Aβ1-40 inhibits both nicotinic and muscarinic-evoked [3H]DA overflow from rat nerve endings. Added to perfusion medium, Aβ1-40 is able to enter into synaptosomes; it exerts its inhibitory effect at extracellular sites when release is stimulated by nAChRs and intracellularly when release is evoked by mAChRs. Moreover, our data show that Aβ1-40 acts as non competitive antagonist of heteromeric α4β2* but not of α3β4* nAChRs which modulate [3H]NA overflow. Positive allosteric modulators of nAChRs counteract its inhibitory effect. It might be that compounds of this type could be useful to prevent, slow down the appearance or reverse the cognitive decline typical of the normal processes of brain aging. PMID:25076904

  3. Evidence for Dynamic Network Regulation of Drosophila Photoreceptor Function from Mutants Lacking the Neurotransmitter Histamine.

    PubMed

    Dau, An; Friederich, Uwe; Dongre, Sidhartha; Li, Xiaofeng; Bollepalli, Murali K; Hardie, Roger C; Juusola, Mikko

    2016-01-01

    Synaptic feedback from interneurons to photoreceptors can help to optimize visual information flow by balancing its allocation on retinal pathways under changing light conditions. But little is known about how this critical network operation is regulated dynamically. Here, we investigate this question by comparing signaling properties and performance of wild-type Drosophila R1-R6 photoreceptors to those of the hdc (JK910) mutant, which lacks the neurotransmitter histamine and therefore cannot transmit information to interneurons. Recordings show that hdc (JK910) photoreceptors sample similar amounts of information from naturalistic stimulation to wild-type photoreceptors, but this information is packaged in smaller responses, especially under bright illumination. Analyses reveal how these altered dynamics primarily resulted from network overload that affected hdc (JK910) photoreceptors in two ways. First, the missing inhibitory histamine input to interneurons almost certainly depolarized them irrevocably, which in turn increased their excitatory feedback to hdc (JK910) R1-R6s. This tonic excitation depolarized the photoreceptors to artificially high potentials, reducing their operational range. Second, rescuing histamine input to interneurons in hdc (JK910) mutant also restored their normal phasic feedback modulation to R1-R6s, causing photoreceptor output to accentuate dynamic intensity differences at bright illumination, similar to the wild-type. These results provide mechanistic explanations of how synaptic feedback connections optimize information packaging in photoreceptor output and novel insight into the operation and design of dynamic network regulation of sensory neurons.

  4. The impact of calcium current reversal on neurotransmitter release in the electrically stimulated retina

    NASA Astrophysics Data System (ADS)

    Werginz, Paul; Rattay, Frank

    2016-08-01

    Objective. In spite of intense theoretical and experimental investigations on electrical nerve stimulation, the influence of reversed ion currents on network activity during extracellular stimulation has not been investigated so far. Approach. Here, the impact of calcium current reversal on neurotransmitter release during subretinal stimulation was analyzed with a computational multi-compartment model of a retinal bipolar cell (BC) that was coupled with a four-pool model for the exocytosis from its ribbon synapses. Emphasis was laid on calcium channel dynamics and how these channels influence synaptic release. Main results. Stronger stimulation with anodic pulses caused transmembrane voltages above the Nernst potential of calcium in the terminals and, by this means, forced calcium ions to flow in the reversed direction from inside to the outside of the cell. Consequently, intracellular calcium concentration decreased resulting in a reduced vesicle release or preventing release at all. This mechanism is expected to lead to a pronounced ring-shaped pattern of exocytosis within a group of neighbored BCs when the stronger stimulated cells close to the electrode fail in releasing vesicles. Significance. Stronger subretinal stimulation causes failure of synaptic exocytosis due to reversal of calcium flow into the extracellular space in cells close to the electrode.

  5. Preparation of Graphene-Modified Acupuncture Needle and Its Application in Detecting Neurotransmitters

    NASA Astrophysics Data System (ADS)

    Tang, Lina; Du, Danxin; Yang, Fan; Liang, Zhong; Ning, Yong; Wang, Hua; Zhang, Guo-Jun

    2015-06-01

    We report a unique nanosensing platform by combining modern nanotechnology with traditional acupuncture needle to prepare graphene-modified acupuncture needle (G-AN), and using it for sensitive detection of neurotransmitters via electrochemistry. An electrochemical deposition method was employed to deposit Au nanoparticles (AuNPs) on the tip surface of the traditional acupuncture needle, while the other part of the needle was coated with insulation paste. Subsequently, the G-AN was obtained by cyclic voltammetry reduction of a graphene oxide solution on the surface of the AuNPs. To investigate the sensing property of the G-AN, pH dependence was measured by recording the open circuit potential in the various pH buffer solutions ranging from 2.0 to 10.0. What’s more, the G-AN was further used for detection of dopamine (DA) with a limit of detection of 0.24 μM. This novel G-AN exhibited a good sensitivity and selectivity, and could realize direct detection of DA in human serum.

  6. High-Probability Neurotransmitter Release Sites Represent an Energy-Efficient Design.

    PubMed

    Lu, Zhongmin; Chouhan, Amit K; Borycz, Jolanta A; Lu, Zhiyuan; Rossano, Adam J; Brain, Keith L; Zhou, You; Meinertzhagen, Ian A; Macleod, Gregory T

    2016-10-10

    Nerve terminals contain multiple sites specialized for the release of neurotransmitters. Release usually occurs with low probability, a design thought to confer many advantages. High-probability release sites are not uncommon, but their advantages are not well understood. Here, we test the hypothesis that high-probability release sites represent an energy-efficient design. We examined release site probabilities and energy efficiency at the terminals of two glutamatergic motor neurons synapsing on the same muscle fiber in Drosophila larvae. Through electrophysiological and ultrastructural measurements, we calculated release site probabilities to differ considerably between terminals (0.33 versus 0.11). We estimated the energy required to release and recycle glutamate from the same measurements. The energy required to remove calcium and sodium ions subsequent to nerve excitation was estimated through microfluorimetric and morphological measurements. We calculated energy efficiency as the number of glutamate molecules released per ATP molecule hydrolyzed, and high-probability release site terminals were found to be more efficient (0.13 versus 0.06). Our analytical model indicates that energy efficiency is optimal (∼0.15) at high release site probabilities (∼0.76). As limitations in energy supply constrain neural function, high-probability release sites might ameliorate such constraints by demanding less energy. Energy efficiency can be viewed as one aspect of nerve terminal function, in balance with others, because high-efficiency terminals depress significantly during episodic bursts of activity.

  7. Stabilization of spontaneous neurotransmitter release at ribbon synapses by ribbon-specific subtypes of Complexin

    PubMed Central

    Vaithianathan, Thirumalini; Zanazzi, George; Henry, Diane; Akmentin, Wendy; Matthews, Gary

    2013-01-01

    Ribbon synapses of tonically releasing sensory neurons must provide a large pool of releasable vesicles for sustained release, while minimizing spontaneous release in the absence of stimulation. Complexins are presynaptic proteins that may accomplish this dual task at conventional synapses, by interacting with the molecular machinery of synaptic vesicle fusion at the active zone to retard spontaneous vesicle exocytosis yet facilitate release evoked by depolarization. However, ribbon synapses of photoreceptor cells and bipolar neurons in the retina express distinct Complexin subtypes, perhaps reflecting the special requirements of these synapses for tonic release. To investigate the role of ribbon-specific Complexins in transmitter release, we combined presynaptic voltage-clamp, fluorescence imaging, electron microscopy, and behavioral assays of photoreceptive function in zebrafish. Acute interference with Complexin function using a peptide derived from the SNARE-binding domain increased spontaneous synaptic vesicle fusion at ribbon synapses of retinal bipolar neurons without affecting release triggered by depolarization. Knockdown of Complexin by injection of an antisense morpholino into zebrafish embryos prevented photoreceptor-driven migration of pigment in skin melanophores and caused the pigment distribution to remain in the dark-adapted state even when embryos were exposed to light. This suggests that loss of Complexin function elevated spontaneous release in illuminated photoreceptors sufficiently to mimic the higher release rate normally associated with darkness, thus interfering with visual signaling. We conclude that visual system-specific Complexins are required for proper illumination-dependent modulation of the rate of neurotransmitter release at visual system ribbon synapses. PMID:23658160

  8. Sources of energy for gating by neurotransmitters in acetylcholine receptor channels.

    PubMed

    Purohit, Prasad; Bruhova, Iva; Auerbach, Anthony

    2012-06-12

    Nicotinic acetylcholine receptors (AChRs) mediate signaling in the central and peripheral nervous systems. The AChR gating conformational change is powered by a low- to high-affinity change for neurotransmitters at two transmitter binding sites. We estimated (from single-channel currents) the components of energy for gating arising from binding site aromatic residues in the α-subunit. All mutations reduced the energy (TyrC1>TrpB≈TyrC2>TyrA), with TyrC1 providing ~40% of the total. Considered one at a time, the fractional energy contributions from the aromatic rings were TrpB ~35%, TyrC1 ~28%, TyrC2 ~28%, and TyrA ~10%. Together, TrpB, TyrC1, and TyrC2 comprise an "aromatic triad" that provides much of the total energy from the transmitter for gating. Analysis of mutant pairs suggests that the energy contributions from some residues are nearly independent. Mutations of TyrC1 cause particularly large energy reductions because they remove two favorable and approximately equal interactions between the aromatic ring and the quaternary amine of the agonist and between the hydroxyl and αLysβ7.

  9. Detection of the inhibitory neurotransmitter GABA in macrophages by magnetic resonance spectroscopy.

    PubMed

    Stuckey, D J; Anthony, D C; Lowe, J P; Miller, J; Palm, W M; Styles, P; Perry, V H; Blamire, A M; Sibson, N R

    2005-08-01

    Macrophages are key components of the inflammatory response to tissue injury, but their activities can exacerbate neuropathology. High-resolution magnetic resonance spectroscopy was used to identify metabolite levels in perchloric acid extracts of cultured cells of the RAW 264.7 murine macrophage line under resting and lipopolysaccharide-activated conditions. Over 25 metabolites were identified including gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter not previously reported to be present in macrophages. The presence of GABA was also demonstrated in extracts of human peripheral blood monocyte-derived macrophages. This finding suggests that there may be communication between damaged central nervous system (CNS) tissue and recruited macrophages and resident microglia, which could help orchestrate the immune response. On activation, lactate, glutamine, glutamate, and taurine levels were elevated significantly, and GABA and alanine were reduced significantly. Strong resonances from glutathione, evident in the macrophage two-dimensional 1H spectrum, suggest that this may have potential as a noninvasive marker of macrophages recruited to the CNS, as it is only present at low levels in normal brain. Alternatively, a specific combination of spectroscopic changes, such as lactate, alanine, glutathione, and polyamines, may prove to be the most accurate means of detecting macrophage recruitment to the CNS.

  10. Ethanol's effects on neurotransmitter release and intracellular free calcium in PC12 cells

    SciTech Connect

    Rabe, C.S.; Weight, F.F.

    1988-01-01

    The effect of ethanol on muscarine-stimulated release of (/sup 3/H)NE was studied using the rat pheochromocytoma cell line, PC12. At concentrations of 25 mM and above, ethanol produced a dose dependent inhibition of muscarine-stimulated release of (/sup 3/H)NE. The inhibition of muscarine-stimulated transmitter release occurred in the absence of any effect of ethanol on (/sup 3/H)NE uptake, metabolism or on muscarinic binding to the cells. However, ethanol produced an inhibition of muscarine-stimulated elevation of intracellular free Ca2+ which corresponded with the inhibition of transmitter release. At concentrations greater than 100 mM, ethanol produced both a stimulation of the release of (/sup 3/H)NE as well as an increase in intracellular free Ca2+. The increase in basal transmitter release and intracellular free Ca2+ occurred independent of the inhibition by ethanol of muscarine-stimulated elevation of intracellular free Ca2+ or transmitter section. These results demonstrate the relationship of the effects of ethanol on cellular free Ca2+ and neurotransmitter release.

  11. Effects of ethanol on neurotransmitter release and intracellular free calcium in PC12 cells

    SciTech Connect

    Rabe, C.S.; Weight, F.F.

    1988-02-01

    The effect of ethanol on muscarine-stimulated release of l-(/sup 3/H)norepinephrine ((/sup 3/H)NE) was studied using the rat pheochromocytoma cell line, PC12. At concentrations of 25 mM and above, ethanol produced a dose-dependent inhibition of muscarine-stimulated release of (/sup 3/H)NE. The inhibition of muscarine-stimulated transmitter release occurred in the absence of any detectable effect of ethanol on (/sup 3/H)NE uptake or on muscarinic binding to the cells. However, ethanol produced an inhibition of muscarine-stimulated elevation of intracellular free Ca++ which corresponded with the inhibition of transmitter release. At concentrations greater than 100 mM, ethanol produced an increase in the basal release of (/sup 3/H)NE. Intracellular free Ca++ also was increased by ethanol concentrations greater than 100 mM. The elevation of basal transmitter release and intracellular free Ca++ by concentrations of ethanol greater than 100 mM occurred independently of the inhibition by ethanol of muscarine-stimulated elevation of intracellular free Ca++ and transmitter secretion. These results suggest that the effects of ethanol on neurotransmitter release are associated with the effects of ethanol on intracellular free Ca++.

  12. Expression of Caenorhabditis elegans neurotransmitter receptors and ion channels in Xenopus oocytes

    PubMed Central

    Martínez-Torres, Ataúlfo; Miledi, Ricardo

    2006-01-01

    Injection of Caenorhabditis elegans polyA RNA into Xenopus laevis oocytes led to the expression of neurotransmitter receptors that generated some unique responses, including ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors as well as receptors that coupled to G proteins, such as those to octopamine, norepinephrine, and angiotensin, which activated the oocyte’s own phosphatidylinositol system and calcium-gated chloride channels. The oocytes also expressed chloride-conducting glutamate receptors, muscarinic acetylcholine receptors, and voltage-operated calcium channels. Unexpectedly, serotonin (5-hydroxytryptamine), dopamine, GABA, and kainate did not generate ionic currents, suggesting that the corresponding receptors were not expressed or were not functional in the oocytes. The use of X. laevis oocytes for expressing worm RNA demonstrates that there are many molecular components whose role remains to be clarified in the nematode. Among them are the nature of the endogenous agonists for the octopamine and angiotensin receptors and the subunits that compose the ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors and the norepinephrine receptors that couple to the phosphoinositide cascade. PMID:16549772

  13. 5×5 CMOS capacitive sensor array for detection of the neurotransmitter dopamine.

    PubMed

    Lu, Michael S-C; Chen, Yi-Chung; Huang, Po-Chiun

    2010-11-15

    This work presents miniaturized CMOS (complementary metal oxide semiconductor) capacitive sensors for detection of the neurotransmitter dopamine (DA) down to the sub-fM range. Sensing resolution is significantly enhanced by monolithic sensor integration to reduce the parasitic effect and the use of sub-μm interdigitated microelectrodes as the sensing interface. The 5 × 5 sensor array contains five designs of different electrode sizes and each design has five sensors. The positive charges produced from protonation of boronate and amino group after immobilization of 4-carboxyphenylboronic acid (CPBA) result in an increase of the electrode-analyte capacitance. Then the negative charges produced after binding of CPBA and DA molecules decrease the electrode-analyte capacitance. Signal transduction is achieved through a CMOS readout circuit whose output frequency is inversely proportional to the capacitance. Experimental results showed the ratios of average percentage capacitance changes of the experiment groups over those of the control groups were all larger than one for the five designs at DA concentration of 0.1 fM. Selectivity against the non-analyte species, such as tyramine, has also been demonstrated.

  14. Live Imaging of Nicotine Induced Calcium Signaling and Neurotransmitter Release Along Ventral Hippocampal Axons.

    PubMed

    Zhong, Chongbo; Talmage, David A; Role, Lorna W

    2015-06-24

    Sustained enhancement of axonal signaling and increased neurotransmitter release by the activation of pre-synaptic nicotinic acetylcholine receptors (nAChRs) is an important mechanism for neuromodulation by acetylcholine (ACh). The difficulty with access to probing the signaling mechanisms within intact axons and at nerve terminals both in vitro and in vivo has limited progress in the study of the pre-synaptic components of synaptic plasticity. Here we introduce a gene-chimeric preparation of ventral hippocampal (vHipp)-accumbens (nAcc) circuit in vitro that allows direct live imaging to analyze both the pre- and post-synaptic components of transmission while selectively varying the genetic profile of the pre- vs post-synaptic neurons. We demonstrate that projections from vHipp microslices, as pre-synaptic axonal input, form multiple, reliable glutamatergic synapses with post-synaptic targets, the dispersed neurons from nAcc. The pre-synaptic localization of various subtypes of nAChRs are detected and the pre-synaptic nicotinic signaling mediated synaptic transmission are monitored by concurrent electrophysiological recording and live cell imaging. This preparation also provides an informative approach to study the pre- and post-synaptic mechanisms of glutamatergic synaptic plasticity in vitro.

  15. Exposure to methylmercury in utero: effects on biochemical development of catecholamine neurotransmitter systems

    SciTech Connect

    Bartolome, J.; Whitmore, W.L.; Seidler, F.J.; Slotkin, T.A.

    1984-08-06

    Administration of methylmercury to pregnant rats resulted in major alterations in synaptic dynamics of brain dopamine systems in the offspring which were prominent even at doses of the organomercurial which did not produce acute toxicity, fetal or neonatal death, low birth weight or reduced litter sizes. The abnormalities were typified by shortfalls in both the levels and turnover rate of the transmitter in vivo, accompanied by elevations in synaptic uptake as assessed in synaptosomal preparations in vitro. These effects were not apparent in the immediate postnatal period but instead showed a delayed onset beginning at about the time of weaning. Methylmercury exposure displayed selectivity in that central noradrenergic systems showed only the synaptic uptake alterations without changes in transmitter levels or turnover; targeted interactions were also apparent in peripheral sympathetic pathways to the heart and kidney. The threshold dose required to elicit damage to biochemical development of neurotransmitter systems was the same as that to alter more generalized cellular development, as assessed through measurements of brain ornithine decarboxylase activity. These studies indicate that neurochemical damage produced by prenatal exposure of the developing organism to methylmercury involves transmitter-selective alterations in synaptic dynamics and function which may contribute to adverse hehavioral outcomes; the underlying mechanisms, however, do not necessarily reflect actions of the organomercurial which are primary or specific to these particular neutronal tissues.

  16. Neurotransmitters as food supplements: the effects of GABA on brain and behavior.

    PubMed

    Boonstra, Evert; de Kleijn, Roy; Colzato, Lorenza S; Alkemade, Anneke; Forstmann, Birte U; Nieuwenhuis, Sander

    2015-01-01

    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human cortex. The food supplement version of GABA is widely available online. Although many consumers claim that they experience benefits from the use of these products, it is unclear whether these supplements confer benefits beyond a placebo effect. Currently, the mechanism of action behind these products is unknown. It has long been thought that GABA is unable to cross the blood-brain barrier (BBB), but the studies that have assessed this issue are often contradictory and range widely in their employed methods. Accordingly, future research needs to establish the effects of oral GABA administration on GABA levels in the human brain, for example using magnetic resonance spectroscopy. There is some evidence in favor of a calming effect of GABA food supplements, but most of this evidence was reported by researchers with a potential conflict of interest. We suggest that any veridical effects of GABA food supplements on brain and cognition might be exerted through BBB passage or, more indirectly, via an effect on the enteric nervous system. We conclude that the mechanism of action of GABA food supplements is far from clear, and that further work is needed to establish the behavioral effects of GABA.

  17. Electrochemical performance of porous diamond-like carbon electrodes for sensing hormones, neurotransmitters, and endocrine disruptors.

    PubMed

    Silva, Tiago A; Zanin, Hudson; May, Paul W; Corat, Evaldo J; Fatibello-Filho, Orlando

    2014-12-10

    Porous diamond-like carbon (DLC) electrodes have been prepared, and their electrochemical performance was explored. For electrode preparation, a thin DLC film was deposited onto a densely packed forest of highly porous, vertically aligned multiwalled carbon nanotubes (VACNT). DLC deposition caused the tips of the carbon nanotubes to clump together to form a microstructured surface with an enlarged surface area. DLC:VACNT electrodes show fast charge transfer, which is promising for several electrochemical applications, including electroanalysis. DLC:VACNT electrodes were applied to the determination of targeted molecules such as dopamine (DA) and epinephrine (EP), which are neurotransmitters/hormones, and acetaminophen (AC), an endocrine disruptor. Using simple and low-cost techniques, such as cyclic voltammetry, analytical curves in the concentration range from 10 to 100 μmol L(-1) were obtained and excellent analytical parameters achieved, including high analytical sensitivity, good response stability, and low limits of detection of 2.9, 4.5, and 2.3 μmol L(-1) for DA, EP, and AC, respectively.

  18. Involvement of multiple calcium channels in neurotransmitter release from cultured sympathetic neurons

    SciTech Connect

    Hirning, L.D.; Perney, T.M.; Miller, R.J.

    1986-03-01

    The release of neurotransmitters has been defined to be a Ca/sup + +/ dependent process, however, the role of Ca/sup + +/ channels in the release process is unclear. Primary cultures of sympathetic nerves from superior cervical ganglia were used to examine the specific actions of dihydropyridine (DHP) drugs. In nerve cultures, /sup 3/H-norepinepharine (NE) was taken up in a desipramine blockable fashion and released on exposure to high external K/sup +/ concentrations. NE release was virtually abolished by Co/sup + +/ (3 mM) or in Ca/sup + +/ free media, demonstrating the Ca/sup + +/ dependence of the release. However, the antagonist DHP, nimodipine, was ineffective in blocking transmitter release in concentrations up to 10/sup -5/M. In contrast, the agonist DHP, Bay K8644 (10/sup -6/M), significantly enhanced transmitter release by 35-40% of control. This enhancement was blocked down to control levels by nimodipine (10/sup -6/M). The authors have also demonstrated high affinity /sup 3/H-nitrendipine binding sites (B/sub max/ = 179 fmoles/mg, Kd = 0.25 nM) on these sympathetic neuronal membranes. These data suggest that DHP sensitive Ca/sup + +/ channels, which have been shown to modulate SP release from DRG neurons in culture are not usually involved in NE release from sympathetic neurons. However, prolonged opening of these channels by the DHP agonist, Bay K8644, increases the overall Ca/sup + +/ influx into sympathetic nerves to enhance transmitter release.

  19. Dopamine Transporter Blockade Increases LTP in the CA1 Region of the Rat Hippocampus via Activation of the D3 Dopamine Receptor

    ERIC Educational Resources Information Center

    Swant, Jarod; Wagner, John J.

    2006-01-01

    Dopamine has been demonstrated to be involved in the modulation of long-term potentiation (LTP) in the CA1 region of the hippocampus. As monoamine transporter blockade will increase the actions of endogenous monoamine neurotransmitters, the effect of a dopamine transporter (DAT) antagonist on LTP was assessed using field excitatory postsynaptic…

  20. Short- and long-term effects of MDMA ("ecstasy") on synaptosomal and vesicular uptake of neurotransmitters in vitro and ex vivo.

    PubMed

    Bogen, Inger Lise; Haug, Kristin Huse; Myhre, Oddvar; Fonnum, Frode

    2003-01-01

    3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") is a commonly abused drug which has been shown to be neurotoxic to serotonergic neurons in many species. The exact mechanism responsible for the neurotoxicity of MDMA is, however, poorly understood. In this study, the effects of MDMA on the synaptosomal and vesicular uptake of neurotransmitters were investigated. Our results show that MDMA (0.5-20 microM) reduces both synaptosomal and vesicular uptake of serotonin and dopamine in a dose dependent manner in vitro, while the uptake of glutamate and gamma-aminobutyric acid (GABA) remains unaffected. Ex vivo experiments support the importance of the monoamines, with predominant dopaminergic inhibition at short-term exposure (3 x 15 mg/kg; 2-h intervals), and exclusively serotonergic inhibition at long-term exposure (2 x 10 mg/kg per day; 4 days). This study also compares MDMA and the structurally related antidepressant paroxetine, in an attempt to reveal possible cellular mechanisms for the serotonergic toxicity of MDMA. One important difference between paroxetine and MDMA is that only MDMA has the capability of inhibiting vesicular uptake of monoamines at doses used. We suggest that inhibition of the vesicular monoamine transporter-2, and a following increase in cytoplasmatic monoamine concentrations, might be crucial for the neurotoxic effect of MDMA.

  1. Predominant role of plasma membrane monoamine transporters in monoamine transport in 1321N1, a human astrocytoma-derived cell line.

    PubMed

    Naganuma, Fumito; Yoshikawa, Takeo; Nakamura, Tadaho; Iida, Tomomitsu; Harada, Ryuichi; Mohsen, Attayeb S; Miura, Yamato; Yanai, Kazuhiko

    2014-05-01

    Monoamine neurotransmitters should be immediately removed from the synaptic cleft to avoid excessive neuronal activity. Recent studies have shown that astrocytes and neurons are involved in monoamine removal. However, the mechanism of monoamine transport by astrocytes is not entirely clear. We aimed to elucidate the transporters responsible for monoamine transport in 1321N1, a human astrocytoma-derived cell line. First, we confirmed that 1321N1 cells transported dopamine, serotonin, norepinephrine, and histamine in a time- and dose-dependent manner. Kinetics analysis suggested the involvement of low-affinity monoamine transporters, such as organic cation transporter (OCT) 2 and 3 and plasma membrane monoamine transporter (PMAT). Monoamine transport in 1321N1 cells was not Na(+) /Cl(-) dependent but was inhibited by decynium-22, an inhibitor of low-affinity monoamine transporters, which supported the importance of low-affinity transporters. RT-PCR assays revealed that 1321N1 cells expressed OCT3 and PMAT but no other neurotransmitter transporters. Another human astrocytoma-derived cell line, U251MG, and primary human astrocytes also exhibited the same gene expression pattern. Gene-knockdown assays revealed that 1321N1 and primary human astrocytes could transport monoamines predominantly through PMAT and partly through OCT3. These results might indicate that PMAT and OCT3 in human astrocytes are involved in monoamine clearance.

  2. Protein kinase A mediates adenosine A2a receptor modulation of neurotransmitter release via synapsin I phosphorylation in cultured cells from medulla oblongata.

    PubMed

    Matsumoto, Joao Paulo Pontes; Almeida, Marina Gomes; Castilho-Martins, Emerson Augusto; Costa, Maisa Aparecida; Fior-Chadi, Debora Rejane

    2014-08-01

    Synaptic transmission is an essential process for neuron physiology. Such process is enabled in part due to modulation of neurotransmitter release. Adenosine is a synaptic modulator of neurotransmitter release in the Central Nervous System, including neurons of medulla oblongata, where several nuclei are involved with neurovegetative reflexes. Adenosine modulates different neurotransmitter systems in medulla oblongata, specially glutamate and noradrenaline in the nucleus tractussolitarii, which are involved in hypotensive responses. However, the intracellular mechanisms involved in this modulation remain unknown. The adenosine A2a receptor modulates neurotransmitter release by activating two cAMP protein effectors, the protein kinase A and the exchange protein activated by cAMP. Therefore, an in vitro approach (cultured cells) was carried out to evaluate modulation of neurotransmission by adenosine A2a receptor and the signaling intracellular pathway involved. Results show that the adenosine A2a receptor agonist, CGS 21680, increases neurotransmitter release, in particular, glutamate and noradrenaline and such response is mediated by protein kinase A activation, which in turn increased synapsin I phosphorylation. This suggests a mechanism of A2aR modulation of neurotransmitter release in cultured cells from medulla oblongata of Wistar rats and suggest that protein kinase A mediates this modulation of neurotransmitter release via synapsin I phosphorylation.

  3. Transverse field focused system

    DOEpatents

    Anderson, O.A.

    1983-06-01

    It is an object of the invention to provide a transport apparatus for a high current negative-ion beam which will bend the beam around corners through a baffled path in a differential pump or a neutron trap. It is another object of the invention to provide a transport apparatus for a high current negative-ion beam which will allow gas molecules in the beam to exit outwardly from the transport apparatus. A further object of the invention is to provide a multi-stage accelerator for a high current negative-ion beam which will enable acceleration of the beam to very high energy levels with a minimum loss of current carrying capacity. A still further object of the invention is to provide an apparatus for transport or accelertion of a sheet beam of negative ions which is shaped to confine the beam against divergence or expansion.

  4. Highly selective and sensitive detection of neurotransmitters using receptor-modified single-walled carbon nanotube sensors

    NASA Astrophysics Data System (ADS)

    Kim, Byeongju; Song, Hyun Seok; Jin, Hye Jun; Park, Eun Jin; Lee, Sang Hun; Lee, Byung Yang; Park, Tai Hyun; Hong, Seunghun

    2013-07-01

    We present receptor-modified carbon nanotube sensors for the highly selective and sensitive detection of acetylcholine (ACh), one kind of neurotransmitter. Here, we successfully expressed the M1 muscarinic acetylcholine receptor (M1 mAChR), a family of G protein-coupled receptors (GPCRs), in E. coli and coated single-walled carbon nanotube (swCNT)-field effect transistors (FETs) with lipid membrane including the receptor, enabling highly selective and sensitive ACh detection. Using this sensor, we could detect ACh at 100 pM concentration. Moreover, we showed that this sensor could selectively detect ACh among other neurotransmitters. This is the first demonstration of the real-time detection of ACh using specific binding between ACh and M1 mAChR, and it may lead to breakthroughs for various applications such as disease diagnosis and drug screening.

  5. Conjugated Polymer Nanoparticles for Fluorescence Imaging and Sensing of Neurotransmitter Dopamine in Living Cells and the Brains of Zebrafish Larvae.

    PubMed

    Qian, Cheng-Gen; Zhu, Sha; Feng, Pei-Jian; Chen, Yu-Lei; Yu, Ji-Cheng; Tang, Xin; Liu, Yun; Shen, Qun-Dong

    2015-08-26

    Nanoscale materials are now attracting a great deal of attention for biomedical applications. Conjugated polymer nanoparticles have remarkable photophysical properties that make them highly advantageous for biological fluorescence imaging. We report on conjugated polymer nanoparticles with phenylboronic acid tags on the surface for fluorescence detection of neurotransmitter dopamine in both living PC12 cells and brain of zebrafish larvae. The selective enrichment of dopamine and fluorescence signal amplification characteristics of the nanoparticles show rapid and high-sensitive probing such neurotransmitter with the detection limit of 38.8 nM, and minimum interference from other endogenous molecules. It demonstrates the potential of nanomaterials as a multifunctional nanoplatform for targeting, diagnosis, and therapy of dopamine-relative disease.

  6. Nicotine induces self-renewal of pancreatic cancer stem cells via neurotransmitter-driven activation of sonic hedgehog signalling.

    PubMed

    Al-Wadei, Mohammed H; Banerjee, Jheelam; Al-Wadei, Hussein A N; Schuller, Hildegard M

    2016-01-01

    A small subpopulation of pancreatic cancer cells with characteristics of stem cells drive tumour initiation, progression and metastasis. A better understanding of the regulation of cancer stem cells may lead to more effective cancer prevention and therapy. We have shown that the proliferation and migration of pancreatic cancer cell lines is activated by the nicotinic receptor-mediated release of stress neurotransmitters, responses reversed by γ-aminobutyric acid (GABA). However, the observed cancer inhibiting effects of GABA will only succeed clinically if GABA inhibits pancreatic cancer stem cells (PCSCs) in addition to the more differentiated cancer cells that comprise the majority of cancer tissues and cell lines. Using PCSCs isolated from two pancreatic cancer patients by cell sorting and by spheroid formation assay from pancreatic cancer cell line Panc-1, we tested the hypothesis that nicotine induces the self-renewal of PCSCs. Nicotinic acetylcholine receptors (nAChRs) α3, α4, α5 and α7 were expressed and chronic exposure to nicotine increased the protein expression of these receptors. Immunoassays showed that PCSCs produced the stress neurotransmitters epinephrine and norepinephrine and the inhibitory neurotransmitter GABA. Chronic nicotine significantly increased the production of stress neurotransmitters and sonic hedgehog (SHH) while inducing Gli1 protein and decreasing GABA. GABA treatment inhibited the induction of SHH and Gli1. Spheroid formation and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide assays showed significant nicotine-induced increases in self renewal and cell proliferation, responses blocked by GABA. Our data suggest that nicotine increases the SHH-mediated malignant potential of PCSCs and that GABA prevents these effects.

  7. An Investigation into the Effects of Peptide Neurotransmitters and Intracellular Second Messengers in Rat Central Neurons in Culture

    DTIC Science & Technology

    1989-06-30

    cerebellum; diencephalon; peptides; cAMP; GABA ; glutamate; histamine; I I Ipresynaptic inhibition 19. ABSTRACT (Continue on reverse if necessary and identify...neurotransmitters glutamate and GABA in Purkinje and granule neurons of the rat cerebellum. (ref. 12) 4) First measurements of changes in free calcium...lasting changes in intracellular calcium are induced by these agonists that could be one possible basis for changing neuronal responsiveness. (ref. 7) 5

  8. Neurotransmitters and neuronal apoptotic cell death of chronically aluminum intoxicated Nile catfish (Clarias gariepinus) in response to ascorbic acid supplementation.

    PubMed

    Khalil, Samah R; Hussein, Mohamed M A

    2015-12-01

    Few studies have been carried out to assess the neurotoxic effect of aluminum (Al) on the aquatic creatures. This study aims to evaluate the neurotoxic effects of long term Al exposure on the Nile catfish (Clarias gariepinus) and the potential ameliorative influence of ascorbic acid (ASA) over a 180 days exposure period. Forty eight Nile catfish were divided into four groups: control group, placed in clean water, ASA exposed group (5mg/l), AlCl3 received group (28.96 μg/l; 1/20 LC50), and group received AlCl3 concomitantly with ASA. Brain tissue was examined by using flow cytometry to monitor the apoptotic cell population, HPLC analysis for the quantitative estimation of brain monoamine neurotransmitters [serotonin (5-HT), dopamine (DA), norepinephrine (NE)]. The amino acid neurotransmitters [serum taurine, glycine, aspartate and glutamine and brain gamma aminobutyric acid (GABA)] levels were assessed, plus changes in brain tissue structure using light microscopy. The concentration of Al in both brain tissue and serum was determined by using atomic absorption spectrophotometery. The Al content in serum and brain tissue were both elevated and Al exposure induced an increase in the number of apoptotic cells, a marked reduction of the monoamine and amino acids neurotransmitters levels and changes in tissue morphology. ASA supplementation partially abolished the effects of AL on the reduced neurotransmitter, the degree of apoptosis and restored the morphological changes to the brain. Overall, our results indicate that, ASA is a promising neuroprotective agent against for Al-induced neurotoxicity in the Nile catfish.

  9. Disorders of consciousness and pharmaceuticals that act on oxygen based amino acid and monoamine neurotransmitter pathways of the brain.

    PubMed

    Clauss, Ralf

    2014-01-01

    Oxygen based neurotransmitters in the synapses of the brain are proposed to play an important role in the generation of consciousness. They include the amino acids glutamate and GABA which use Krebs cycle precursors for their synthesis, and the monoamines dopamine, noradrenalin, adrenalin and serotonin, which are derived from tyrosine and tryptophan. During ischemia after an acute brain injury, a GABA surge often initiates brain suppression. It has been proposed that with chronic ischemia, a secondary, possibly epigenetic response occurs when neurotransmitters deplete, a glucose and oxygen saving mechanism termed neurodormancy that may invoke alternative long term low energy metabolic pathways in the brain, encountered in Disorders of Consciousness. Some medications can reverse Disorders of Consciousness in some patients. Virtually all of them act on neurotransmitter systems that use oxygen as a building block or as an energy source within the brain. Pharmaceuticals that act in the oxygen based amino acid systems of the brain include the GABAergic medications zolpidem and baclofen, while those that act in the monoamine axes include the dopaminergic medications L Dopa, amantadine, bromocriptine, apomorphine and methylphenidate, and the noradrenergic and serotonergic medications desipramine, amitriptyline, protriptyline and fluoxetine. Another group are the cholinesterase inhibitors, responsible for increasing acetylcholine, which is synthesized from the Krebs cycle initiator, acetyl CoA. It appears that pharmaceuticals that are active in the oxygen based neurotransmitter pathways of the brain are successful to arouse to consciousness patients that suffer from its disorders. Research needs to be supported as foundation to understand the biochemical mechanisms that are involved in consciousness disorders and to explore further the pharmacological treatment possibilities for these devastating neurological conditions.

  10. Effect of Low-Intensity Microwave Radiation on Monoamine Neurotransmitters and Their Key Regulating Enzymes in Rat Brain.

    PubMed

    Megha, Kanu; Deshmukh, Pravin S; Ravi, Alok K; Tripathi, Ashok K; Abegaonkar, Mahesh P; Banerjee, Basu D

    2015-09-01

    The increasing use of wireless communication devices has raised major concerns towards deleterious effects of microwave radiation on human health. The aim of the study was to demonstrate the effect of low-intensity microwave radiation on levels of monoamine neurotransmitters and gene expression of their key regulating enzymes in brain of Fischer rats. Animals were exposed to 900 MHz and 1800 MHz microwave radiation for 30 days (2 h/day, 5 days/week) with respective specific absorption rates as 5.953 × 10(-4) and 5.835 × 10(-4) W/kg. The levels of monoamine neurotransmitters viz. dopamine (DA), norepinephrine (NE), epinephrine (E) and serotonin (5-HT) were detected using LC-MS/MS in hippocampus of all experimental animals. In addition, mRNA expression of key regulating enzymes for these neurotransmitters viz. tyrosine hydroxylase (TH) (for DA, NE and E) and tryptophan hydroxylase (TPH1 and TPH2) (for serotonin) was also estimated. Results showed significant reduction in levels of DA, NE, E and 5-HT in hippocampus of microwave-exposed animals in comparison with sham-exposed (control) animals. In addition, significant downregulation in mRNA expression of TH, TPH1 and TPH2 was also observed in microwave-exposed animals (p < 0.05). In conclusion, the results indicate that low-intensity microwave radiation may cause learning and memory disturbances by altering levels of brain monoamine neurotransmitters at mRNA and protein levels.

  11. Transendothelial Transport and Its Role in Therapeutics

    PubMed Central

    Upadhyay, Ravi Kant

    2014-01-01

    Present review paper highlights role of BBB in endothelial transport of various substances into the brain. More specifically, permeability functions of BBB in transendothelial transport of various substances such as metabolic fuels, ethanol, amino acids, proteins, peptides, lipids, vitamins, neurotransmitters, monocarbxylic acids, gases, water, and minerals in the peripheral circulation and into the brain have been widely explained. In addition, roles of various receptors, ATP powered pumps, channels, and transporters in transport of vital molecules in maintenance of homeostasis and normal body functions have been described in detail. Major role of integral membrane proteins, carriers, or transporters in drug transport is highlighted. Both diffusion and carrier mediated transport mechanisms which facilitate molecular trafficking through transcellular route to maintain influx and outflux of important nutrients and metabolic substances are elucidated. Present review paper aims to emphasize role of important transport systems with their recent advancements in CNS protection mainly for providing a rapid clinical aid to patients. This review also suggests requirement of new well-designed therapeutic strategies mainly potential techniques, appropriate drug formulations, and new transport systems for quick, easy, and safe delivery of drugs across blood brain barrier to save the life of tumor and virus infected patients. PMID:27355037

  12. Simultaneous imaging of multiple neurotransmitters and neuroactive substances in the brain by desorption electrospray ionization mass spectrometry.

    PubMed

    Shariatgorji, Mohammadreza; Strittmatter, Nicole; Nilsson, Anna; Källback, Patrik; Alvarsson, Alexandra; Zhang, Xiaoqun; Vallianatou, Theodosia; Svenningsson, Per; Goodwin, Richard J A; Andren, Per E

    2016-08-01

    With neurological processes involving multiple neurotransmitters and neuromodulators, it is important to have the ability to directly map and quantify multiple signaling molecules simultaneously in a single analysis. By utilizing a molecular-specific approach, namely desorption electrospray ionization mass spectrometry imaging (DESI-MSI), we demonstrated that the technique can be used to image multiple neurotransmitters and their metabolites (dopamine, dihydroxyphenylacetic acid, 3-methoxytyramine, serotonin, glutamate, glutamine, aspartate, γ-aminobutyric acid, adenosine) as well as neuroactive drugs (amphetamine, sibutramine, fluvoxamine) and drug metabolites in situ directly in brain tissue sections. The use of both positive and negative ionization modes increased the number of identified molecular targets. Chemical derivatization by charge-tagging the primary amines of molecules significantly increased the sensitivity, enabling the detection of low abundant neurotransmitters and other neuroactive substances previously undetectable by MSI. The sensitivity of the imaging approach of neurochemicals has a great potential in many diverse applications in fields such as neuroscience, pharmacology, drug discovery, neurochemistry, and medicine.

  13. Two-step production of monoamines in monoenzymatic cells in the spinal cord: a different control strategy of neurotransmitter supply?

    PubMed Central

    Zhang, Mengliang

    2016-01-01

    Monoamine neurotransmitters play an important role in the modulation of sensory, motor and autonomic functions in the spinal cord. Although traditionally it is believed that in mammalian spinal cord, monoamine neurotransmitters mainly originate from the brain, accumulating evidence indicates that especially when the spinal cord is injured, they can also be produced in the spinal cord. In this review, I will present evidence for a possible pathway for two-step synthesis of dopamine and serotonin in the spinal cord. Published data from different sources and unpublished data from my own ongoing projects indicate that monoenzymatic cells expressing aromatic L-amino acid decarboxylase (AADC), tyrosine hydroxylase (TH) or tryptophan hydroxylase (TPH) are present in the spinal cord and that these TH and THP cells often lie in close proximity to AADC cells. Prompted by the above evidence, I hypothesize that dopamine and serotonin could be synthesized sequentially in two monoenzymatic cells in the spinal cord via a TH-AADC and a TPH-AADC cascade respectively. The monoamines synthesized through this pathway may compensate for lost neurotransmitters following spinal cord injury and also may play specific roles in the recovery of sensory, motor and autonomic functions. PMID:28197177

  14. Detection of neurotransmitters by a light scattering technique based on seed-mediated growth of gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Shang, Li; Dong, Shaojun

    2008-03-01

    A simple light scattering detection method for neurotransmitters has been developed, based on the growth of gold nanoparticles. Neurotransmitters (dopamine, L-dopa, noradrenaline and adrenaline) can effectively function as active reducing agents for generating gold nanoparticles, which result in enhanced light scattering signals. The strong light scattering of gold nanoparticles then allows the quantitative detection of the neurotransmitters simply by using a common spectrofluorometer. In particular, Au-nanoparticle seeds were added to facilitate the growth of nanoparticles, which was found to enhance the sensing performance greatly. Using this light scattering technique based on the seed-mediated growth of gold nanoparticles, detection limits of 4.4 × 10-7 M, 3.5 × 10-7 M, 4.1 × 10-7 M, and 7.7 × 10-7 M were achieved for dopamine, L-dopa, noradrenaline and adrenaline, respectively. The present strategy can be extended to detect other biologically important molecules in a very fast, simple and sensitive way, and may have potential applications in a wide range of fields.

  15. Vanillin-induced amelioration of depression-like behaviors in rats by modulating monoamine neurotransmitters in the brain.

    PubMed

    Xu, Jinyong; Xu, Hui; Liu, Yang; He, Haihui; Li, Guangwu

    2015-02-28

    Olfaction plays an important role in emotions in our daily life. Pleasant odors are known to evoke positive emotions, inducing relaxation and calmness. The beneficial effects of vanillin on depressive model rats were investigated using a combination of behavioral assessments and neurotransmitter measurements. Before and after chronic stress condition (or olfactory bulbectomy), and at the end of vanillin or fluoxetine treatment, body weight, immobility time on the forced swimming test and sucrose consumption in the sucrose consumption test were measured. Changes in these assessments revealed the characteristic phenotypes of depression in rats. Neurotransmitters were measured using ultrahigh-performance liquid chromatography. Our results indicated that vanillin could alleviate depressive symptoms in the rat model of chronic depression via the olfactory pathway. Preliminary analysis of the monoamine neurotransmitters revealed that vanillin elevated both serotonin and dopamine levels in brain tissue. These results provide important mechanistic insights into the protective effect of vanillin against chronic depressive disorder via olfactory pathway. This suggests that vanillin may be a potential pharmacological agent for the treatment of major depressive disorder.

  16. Two-step production of monoamines in monoenzymatic cells in the spinal cord: a different control strategy of neurotransmitter supply?

    PubMed

    Zhang, Mengliang

    2016-12-01

    Monoamine neurotransmitters play an important role in the modulation of sensory, motor and autonomic functions in the spinal cord. Although traditionally it is believed that in mammalian spinal cord, monoamine neurotransmitters mainly originate from the brain, accumulating evidence indicates that especially when the spinal cord is injured, they can also be produced in the spinal cord. In this review, I will present evidence for a possible pathway for two-step synthesis of dopamine and serotonin in the spinal cord. Published data from different sources and unpublished data from my own ongoing projects indicate that monoenzymatic cells expressing aromatic L-amino acid decarboxylase (AADC), tyrosine hydroxylase (TH) or tryptophan hydroxylase (TPH) are present in the spinal cord and that these TH and THP cells often lie in close proximity to AADC cells. Prompted by the above evidence, I hypothesize that dopamine and serotonin could be synthesized sequentially in two monoenzymatic cells in the spinal cord via a TH-AADC and a TPH-AADC cascade respectively. The monoamines synthesized through this pathway may compensate for lost neurotransmitters following spinal cord injury and also may play specific roles in the recovery of sensory, motor and autonomic functions.

  17. Physiological and chemical analysis of neurotransmitter candidates at a fast excitatory synapse in the jellyfish Cyanea capillata (Cnidaria, Scyphozoa).

    PubMed

    Anderson, Peter A V; Trapido-Rosenthal, H G

    2009-12-01

    Motor nerve net (MNN) neurons in the jellyfish Cyanea capillata communicate with one another by way of fast, bidirectional excitatory chemical synapses. As is the case with almost all identified chemical synapses in cnidarians, the identity of the neurotransmitter at these synapses is unclear. MNN neurons are large enough for stable intracellular recordings. This, together with the fact that they can be exposed, providing unlimited access to them and to their synapses, prompted a study of the action of a variety of neurotransmitter candidates, including those typically associated with fast synapses in higher animals. Only the amino acids taurine and beta-alanine produced physiological responses consistent with those of the normal EPSP in these cells. Moreover, chemical analysis revealed that both taurine and beta-alanine are present in the neurons and released by depolarization. These various findings strongly suggest that either or both of these amino acids, or a closely related compound is the neurotransmitter at the fast chemical synapses between MNN neurons.

  18. Synaptic PI(3,4,5)P3 is required for Syntaxin1A clustering and neurotransmitter release.

    PubMed

    Khuong, Thang Manh; Habets, Ron L P; Kuenen, Sabine; Witkowska, Agata; Kasprowicz, Jaroslaw; Swerts, Jef; Jahn, Reinhard; van den Bogaart, Geert; Verstreken, Patrik

    2013-03-20

    PI(3,4,5)P3 is a low-abundance lipid thought to play a role in the regulation of synaptic activity; however, the mechanism remains obscure. We have constructed novel split Venus-based probes and used superresolution imaging to localize PI(3,4,5)P3 at Drosophila larval neuromuscular synapses. We find the lipid in membrane domains at neurotransmitter release sites, where it concentrates with Syntaxin1A, a protein essential for vesicle fusion. Reducing PI(3,4,5)P3 availability disperses Syntaxin1A clusters and increasing PI(3,4,5)P3 levels rescues this defect. In artificial giant unilamellar vesicles, PI(3,4,5)P3 also induces Syntaxin1A domain formation and this clustering, in vitro and in vivo, is dependent on positively charged residues in the Syntaxin1A-juxtamembrane domain. Functionally, reduced PI(3,4,5)P3 causes temperature-sensitive paralysis and reduced neurotransmitter release, a phenotype also seen in animals expressing a Syntaxin1A with a mutated juxtamembrane domain. Thus, our data indicate that PI(3,4,5)P3, based on electrostatic interactions, clusters Syntaxin1A at release sites to regulate neurotransmitter release.

  19. Planar Diamond-Based Multiarrays to Monitor Neurotransmitter Release and Action Potential Firing: New Perspectives in Cellular Neuroscience.

    PubMed

    Carabelli, Valentina; Marcantoni, Andrea; Picollo, Federico; Battiato, Alfio; Bernardi, Ettore; Pasquarelli, Alberto; Olivero, Paolo; Carbone, Emilio

    2017-02-15

    High biocompatibility, outstanding electrochemical responsiveness, inertness, and transparency make diamond-based multiarrays (DBMs) first-rate biosensors for in vitro detection of electrochemical and electrical signals from excitable cells together, with potential for in vivo applications as neural interfaces and prostheses. Here, we will review the electrochemical and physical properties of various DBMs and how these devices have been employed for recording released neurotransmitter molecules and all-or-none action potentials from living cells. Specifically, we will overview how DBMs can resolve localized exocytotic events from subcellular compartments using high-density microelectrode arrays (MEAs), or monitoring oxidizable neurotransmitter release from populations of cells in culture and tissue slices using low-density MEAs. Interfacing DBMs with excitable cells is currently leading to the promising opportunity of recording electrical signals as well as creating neuronal interfaces through the same device. Given the recent increasingly growing development of newly available DBMs of various geometries to monitor electrical activity and neurotransmitter release in a variety of excitable and neuronal tissues, the discussion will be limited to planar DBMs.

  20. The essential oil of bergamot enhances the levels of amino acid neurotransmitters in the hippocampus of rat: implication of monoterpene hydrocarbons.

    PubMed

    Morrone, Luigi A; Rombolà, Laura; Pelle, Cinzia; Corasaniti, Maria T; Zappettini, Simona; Paudice, Paolo; Bonanno, Giambattista; Bagetta, Giacinto

    2007-04-01

    The effects of bergamot essential oil (BEO) on the release of amino acid neurotransmitters in rat hippocampus have been studied by in vivo microdialysis and by in vitro superfusion of isolated nerve terminals. Intraperitoneal administration of BEO (100microl/kg) significantly elevated the extracellular concentration of aspartate, glycine and taurine in a Ca(2+)-dependent manner. A dose-relation study generated a bell-shaped curve. When perfused into the hippocampus via the dialysis probe (20microl/20min), BEO produced a significant increase of extracellular aspartate, glycine, taurine as well as of GABA and glutamate. The augmentation of all amino acids was Ca(2+)-independent. Focally injected 1:1 diluted BEO preferentially caused extracellular increase of glutamate. Interestingly, this release appeared to be strictly Ca(2+)-dependent. BEO concentration-dependently enhanced the release of [(3)H]D-aspartate from superfused hippocampal synaptosomes. Similar results were obtained by monitoring the BEO-evoked release of endogenous glutamate. At relatively high concentrations, the BEO-induced [(3)H]d-aspartate release was almost entirely prevented by the glutamate transporter blocker dl-threo-beta-benzyloxyaspartic acid (DL-TBOA) and was Ca(2+)-independent. At relatively low concentrations the release of [(3)H]D-aspartate was only in part ( approximately 50%) DL-TBOA-sensitive and Ca(2+)-independent; the remaining portion of release was dependent on extracellular Ca(2+). Interestingly, the monoterpene hydrocarbon-free fraction of the essential oil appeared to be inactive while the bergapten-free fraction superimposed the releasing effect of BEO supporting the deduction that psoralens may not be implicated. To conclude, BEO contains into its volatile fraction still unidentified monoterpene hydrocarbons able to stimulate glutamate release by transporter reversal and/or by exocytosis, depending on the dose administered.

  1. The cost of transportation`s oil dependence

    SciTech Connect

    Greene, D.L.

    1995-05-01

    Transportation is critical to the world`s oil dependence problem because of the large share of world oil it consumes and because of its intense dependence on oil. This paper will focus on the economic costs of transportation`s oil dependence.

  2. Microfabricated particle focusing device

    DOEpatents

    Ravula, Surendra K.; Arrington, Christian L.; Sigman, Jennifer K.; Branch, Darren W.; Brener, Igal; Clem, Paul G.; James, Conrad D.; Hill, Martyn; Boltryk, Rosemary June

    2013-04-23

    A microfabricated particle focusing device comprises an acoustic portion to preconcentrate particles over large spatial dimensions into particle streams and a dielectrophoretic portion for finer particle focusing into single-file columns. The device can be used for high throughput assays for which it is necessary to isolate and investigate small bundles of particles and single particles.

  3. FOCUS: Sustainable Mathematics Successes

    ERIC Educational Resources Information Center

    Mireles, Selina V.; Acee, Taylor W.; Gerber, Lindsey N.

    2014-01-01

    The FOCUS (Fundamentals of Conceptual Understanding and Success) Co-Requisite Model Intervention (FOCUS Intervention) for College Algebra was developed as part of the Developmental Education Demonstration Projects (DEDP) in Texas. The program was designed to use multiple services, courses, and best practices to support student completion of a…

  4. Focus, 2000-2001.

    ERIC Educational Resources Information Center

    Focus, 2001

    2001-01-01

    These three issues of 2000-2001 "Focus" present a collection of papers focusing on issues related to poverty. The first issue discusses child support enforcement policy and low-income families, highlighting such issues as fragile families and child wellbeing; low-income families and the child support enforcement system; child support…

  5. Novel orthogonal liquid chromatography methods to dose neurotransmitters involved in Parkinson's disease.

    PubMed

    Sardella, Roccaldo; Scorzoni, Stefania; Conte, Carmela; Lisanti, Antonella; Ianni, Federica; Natalini, Benedetto

    2014-09-01

    Parkinson's disease is a multifactorial neurodegenerative disorder, characterized by a reduction of dopamine (DA) levels. The molecular pathways involved in the pathogenesis of disease have not yet been fully disclosed. Therefore, developing new diagnostic methods and tools to evaluate the depletion of DA and of some of its metabolites (3,4-dihydroxyphenylacetic acid, homovanillic acid, and 3-methoxytyramine) is of outstanding importance for biochemical evaluations. Moreover, neurons responsible for DA release also produce the neurotransmitter gamma-aminobutyric acid (GABA), thus, quantitative measurements of GABA levels can have a relevant impact for a further understanding of the biochemical processes involved in the neurodegenerative event. In the present study, two HPLC methods based on the reversed-phase ion-pairing chromatography (RP-IPC) and the hydrophilic liquid interaction chromatography (HILIC) concepts were developed to allow the quantification of DA and its metabolites as well as GABA levels in mouse striatal and cortical tissue homogenates. The two fairly orthogonal HPLC methods were directly applied to the biological samples, without preliminary derivatization of the compounds of interest. A high level of selectivity was obtained for DA metabolites and GABA by running the gradient RP-IPC method with a volatile ion-pairing reagent, which makes it suitable for the quantitative assay of four out of five compounds. Matrix deriving interferences unabled the base-line separation of DA which was instead successfully achieved with the HILIC-based method. To avail of HPLC methods providing distinct selectivity profiles, makes possible the correct species quantification and allows to compensate the intrinsic limits characterizing all chromatographic methods.

  6. Associations between purine metabolites and monoamine neurotransmitters in first-episode psychosis

    PubMed Central

    Yao, Jeffrey K.; Dougherty, George G.; Reddy, Ravinder D.; Matson, Wayne R.; Kaddurah-Daouk, Rima; Keshavan, Matcheri S.

    2013-01-01

    Schizophrenia (SZ) is a biochemically complex disorder characterized by widespread defects in multiple metabolic pathways whose dynamic interactions, until recently, have been difficult to examine. Rather, evidence for these alterations has been collected piecemeal, limiting the potential to inform our understanding of the interactions amongst relevant biochemical pathways. We herein review perturbations in purine and neurotransmitter metabolism observed in early SZ using a metabolomic approach. Purine catabolism is an underappreciated, but important component of the homeostatic response of mitochondria to oxidant stress. We have observed a homeostatic imbalance of purine catabolism in first-episode neuroleptic-naïve patients with SZ (FENNS). Precursor and product relationships within purine pathways are tightly correlated. Although some of these correlations persist across disease or medication status, others appear to be lost among FENNS suggesting that steady formation of the antioxidant uric acid (UA) via purine catabolism is altered early in the course of illness. As is the case for within-pathway correlations, there are also significant cross-pathway correlations between respective purine and tryptophan (TRP) pathway metabolites. By contrast, purine metabolites show significant cross-pathway correlation only with tyrosine, and not with its metabolites. Furthermore, several purine metabolites (UA, guanosine, or xanthine) are each significantly correlated with 5-hydroxyindoleacetic acid (5-HIAA) in healthy controls, but not in FENNS at baseline or 4-week after antipsychotic treatment. Taken together, the above findings suggest that purine catabolism strongly associates with the TRP pathways leading to serotonin (5-hydroxytryptamine, 5-HT) and kynurenine metabolites. The lack of a significant correlation between purine metabolites and 5-HIAA, suggests alterations in key 5-HT pathways that may both be modified by and contribute to oxidative stress via purine

  7. Nicotine-induced monoamine neurotransmitter changes in the brain of young rats.

    PubMed

    Shearman, E; Fallon, S; Sershen, H; Lajtha, A

    2008-08-15

    A number of studies in various species including man indicated a greater risk of drug preference and addictive behavior in young as compared to adults. Such age dependent preference was also found with nicotine. To examine possible mechanisms for this difference in our continuing study of reward mechanisms, we compared nicotine-induced neurotransmitter changes in the brain regions of adult and young Sprague-Dawley rats, assaying the transmitters via microdialysis in conscious freely moving animals. In general, nicotine-induced changes were significantly less in the regions measured in the young. Nicotine-induced effects on dopamine in the dorsal and ventral hippocampus (VH), prefrontal and medial temporal cortex, and superior cerebral peduncle were lower in the young than in adult, the same in the ventral tegmental area (VTA) and lateral septal nucleus (LS), and somewhat higher in the nucleus accumbens shell (NAccS). Norepinephrine levels in the young were lower in all areas except in the VH where they were the same, and serotonin levels were lower except in the VTA and LS where they remained the same, and higher in the NAccS. Age-dependent differences in the metabolites measured were more mixed. We conclude that the greater nicotine preference in young is not paralleled by a greater effect of nicotine on the release of monoamines at least in most of the brain areas assayed. Thus, increases of nicotine reward are not likely due to increases of monoamines in reward and cognitive areas. The small increase of dopamine (DA) and more significant increase of serotonin (5-HT) only in the NAccS are of significance, and would indicate a more significant role of 5-HT than of DA at least in the age difference in nicotine preference. Developmental changes in receptor composition and distribution involving several transmitter systems and other components such as neuropeptides are also likely to play a role.

  8. Raised tone reveals ATP as a sympathetic neurotransmitter in the porcine mesenteric arterial bed.

    PubMed

    Shatarat, Amjad; Dunn, William R; Ralevic, Vera

    2014-12-01

    The relative importance of ATP as a functional sympathetic neurotransmitter in blood vessels has been shown to be increased when the level of preexisting vascular tone or pressure is increased, in studies carried out in rat mesenteric arteries. The aim of the present study was to determine whether tone influences the involvement of ATP as a sympathetic cotransmitter with noradrenaline in another species. We used the porcine perfused mesenteric arterial bed and porcine mesenteric large, medium and small arteries mounted for isometric tension recording, because purinergic cotransmission can vary depending on the size of the blood vessel. In the perfused mesenteric bed at basal tone, sympathetic neurogenic vasocontractile responses were abolished by prazosin, an α1-adrenoceptor antagonist, but there was no significant effect of α,β-methylene ATP, a P2X receptor-desensitizing agent. Submaximal precontraction of the mesenteric arterial bed with U46619, a thromboxane A2 mimetic, augmented the sympathetic neurogenic vasocontractile responses; under these conditions, both α,β-methylene ATP and prazosin attenuated the neurogenic responses. In the mesenteric large, medium and small arteries, prazosin attenuated the sympathetic neurogenic contractile responses under conditions of both basal and U46619-raised tone. α,β-Methylene ATP was effective in all of these arteries only under conditions of U46619-induced tone, causing a similar inhibition in all arteries, but had no significant effect on sympathetic neurogenic contractions at basal tone. These data show that ATP is a cotransmitter with noradrenaline in porcine mesenteric arteries; the purinergic component was revealed under conditions of partial precontraction, which is more relevant to physiological conditions.

  9. Towards timely Alzheimer diagnosis: A self-powered amperometric biosensor for the neurotransmitter acetylcholine.

    PubMed

    Moreira, Felismina T C; Sale, M Goreti F; Di Lorenzo, Mirella

    2017-01-15

    Serious brain disorders, such as the Alzheimer's Disease (AD), are associated with a marked drop in the levels of important neurotransmitters, such as acetylcholine (ACh). Real time monitoring of such biomarkers can therefore play a critical role in enhancing AD therapies by allowing timely diagnosis, verifications of treatment effectiveness, and developments of new medicines. In this study, we present the first acetylcholine/oxygen hybrid enzymatic fuel cell for the self-powered on site detection of ACh in plasma, which is based on the combination of an enzymatic anode with a Pt cathode. Firstly, an effective acetylcholinesterase immobilized electrode was developed and its electrochemical performance evaluated. Highly porous gold was used as the electrode material, and the enzyme was immobilized via a one step rapid and simple procedure that does not require the use of harsh chemicals or any electrode/enzyme pre-treatments. The resulting enzymatic electrode was subsequently used as the anode of a miniature flow-through membrane-less fuel cell and showed excellent response to varying concentrations of ACh. The peak power generated by the fuel cell was 4nW at a voltage of 260mV and with a current density of 9μAcm(-2). The limit of detection of the fuel cell sensor was 10μM, with an average response time as short as 3min. These exciting results open new horizons for point-of-care Alzheimer diagnosis and provide an attractive potential alternative to established methods that require laborious and time-consuming sample treatments and expensive instruments.

  10. The action of orexin B on passive avoidance learning. Involvement of neurotransmitters.

    PubMed

    Palotai, Miklós; Telegdy, Gyula; Ekwerike, Alphonsus; Jászberényi, Miklós

    2014-10-01

    The extensive projection of orexigenic neurons and the diffuse expression of orexin receptors suggest that endogenous orexins are involved in several physiological functions of the central nervous system, including learning and memory. Our previous study demonstrated that orexin A improves learning, consolidation and retrieval processes, which involves α- and β-adrenergic, cholinergic, dopaminergic, GABA-A-ergic, opiate and nitrergic neurotransmissions. However, we have little evidence about the action of orexin B on memory processes and the underlying neuromodulation. Therefore, the aim of the present study was to investigate the action of orexin B on passive avoidance learning and the involvement of neurotransmitters in this action in rats. Accordingly, rats were pretreated with the selective orexin 2 receptor (OX2R) antagonist, EMPA; the γ-aminobutyric acid subunit A (GABA-A) receptor antagonist, the bicuculline; a D2, D3, D4 dopamine receptor antagonist, haloperidol; the nonselective opioid receptor antagonist, naloxone; the non-specific nitric oxide synthase (NOS) inhibitor, nitro-l-arginine; the nonselective α-adrenergic receptor antagonist, phenoxybenzamine and the β-adrenergic receptor antagonist, propranolol. Our results demonstrate that orexin B can improve learning, consolidation of memory and retrieval. EMPA reversed completely the action of orexin B on memory consolidation. Bicuculline blocked fully; naloxone, nitro-l-arginine, phenoxybenzamine and propranolol attenuated the orexin B-induced memory consolidation, whereas haloperidol was ineffective. These data suggest that orexin B improves memory functions through OX2R and GABA-ergic, opiate, nitrergic, α- and β-adrenergic neurotransmissions are also involved in this action.

  11. [Neurotransmitter systems in the human brain studied by positron emission tomography].

    PubMed

    Shinotoh, H

    1996-12-01

    Positron emission tomography with appropriate tracers provides unique opportunity to study neurotransmitter systems in the living human brain. PET with [18F] 6-fluoro-L-dopa (FD) provides an index of the integrity of nigrostriatal pathway, and striatal FD uptake correlates linearly with the density of nigral neurons. PET allows us to assess the progression of the nigral lesions in Parkinson's disease (PD). A 68-year-old normal female volunteer was scanned by FD-PET. Subsequently, she developed parkinsonism 3.7 years after the scan. A repeated FD-PET scan revealed a significant reduction of FD uptake by 20% over the 5.2 year interval. The results suggest a relatively short presymptomatic period with fast initial losses of nigral neurons in PD. FD-PET has been used to determine the viability of fetal graft implanted in the striatum for the treatment of PD. PET imaging of dopamine D1 and D2 receptors may be useful for the differential diagnosis of PD and striatonigral degeneration. PET reveals significant reduction of dopamine D1 and D2 receptor binding in the putamen of patients with SND, while D1 and D2 receptor binding is normal or slightly upregulated in PD. We found hypersensitivity of muscarinic cholinergic receptors in the frontal cortex of patients with PD by using PET. The result suggests a loss of ascending cholinergic system in the frontal cortex in PD, which may cause the frontal lobe dysfunction in PD. Recently, acetylcholine analogs labelled with positron emitter have been developed for measurement of brain acetylcholinesterase activity in vivo. These tracers may be useful for the assessment of ascending cholinergic system in Alzheimer's disease and PD.

  12. [In vivo visualization of neurotransmitter function in the human brain by PET].

    PubMed

    Itoh, M; Yanai, K; Yamaguchi, S; Fujiwara, T; Nagasawa, H; Yokoyama, H; Iinuma, K; Ido, T

    1995-03-01

    Measurement of cerebral blood flow and energy metabolism using PET with 15O and 18F labeled tracers allows quantitative evaluation of cerebral metabolism that can be perturbed in pathological states. Neurotransmission is a new target that is visualized by labeling of substrates of enzymes that are involved in neurotransmitter synthesis or degradation. Neuronal receptors are mapped by introducing the labeled ligands that are specifically bound to the receptors in question. We developed unique tracers that label dopamine D2 or histamine H1 receptors. With other available ligands for the muscarinic cholinergic receptors and [18F] fluorodopa, we started clinical investigations to document the state of neurotransmission in patients with epilepsy, Parkinson's disease and dementia. Using [11C] doxepin we observed an increase of H1 receptors in the epileptic foci that showed decreased glucose metabolic rate at the interictal phase. This phenomenon is compatible with reported increase of mu opiate receptors in the brains of epileptic patients. Brain uptake of FDOPA (Ki), calculated by the graphical plot was found relatively stable with age both in the normal population and dementia patients. However, the striatal Ki of FDOPA of severely demented patients significantly reduced, compared with the normal aged subjects. The correlation analysis between FDOPA Ki and severity of dementia as assessed by mini-mental state examination revealed a significant reduction of Ki associated with the disease progression. Increase in D2 receptor density as assessed by the uptake of YM 09151-2 was observed in cases with reduced FDOPA uptake, which may correspond to the state of supersensitivity of the D2 receptors.

  13. Evidence for Dynamic Network Regulation of Drosophila Photoreceptor Function from Mutants Lacking the Neurotransmitter Histamine

    PubMed Central

    Dau, An; Friederich, Uwe; Dongre, Sidhartha; Li, Xiaofeng; Bollepalli, Murali K.; Hardie, Roger C.; Juusola, Mikko

    2016-01-01

    Synaptic feedback from interneurons to photoreceptors can help to optimize visual information flow by balancing its allocation on retinal pathways under changing light conditions. But little is known about how this critical network operation is regulated dynamically. Here, we investigate this question by comparing signaling properties and performance of wild-type Drosophila R1–R6 photoreceptors to those of the hdcJK910 mutant, which lacks the neurotransmitter histamine and therefore cannot transmit information to interneurons. Recordings show that hdcJK910 photoreceptors sample similar amounts of information from naturalistic stimulation to wild-type photoreceptors, but this information is packaged in smaller responses, especially under bright illumination. Analyses reveal how these altered dynamics primarily resulted from network overload that affected hdcJK910 photoreceptors in two ways. First, the missing inhibitory histamine input to interneurons almost certainly depolarized them irrevocably, which in turn increased their excitatory feedback to hdcJK910 R1–R6s. This tonic excitation depolarized the photoreceptors to artificially high potentials, reducing their operational range. Second, rescuing histamine input to interneurons in hdcJK910 mutant also restored their normal phasic feedback modulation to R1–R6s, causing photoreceptor output to accentuate dynamic intensity differences at bright illumination, similar to the wild-type. These results provide mechanistic explanations of how synaptic feedback connections optimize information packaging in photoreceptor output and novel insight into the operation and design of dynamic network regulation of sensory neurons. PMID:27047343

  14. Functional localization of neurotransmitter receptors and synaptic inputs to mature neurons of the medial superior olive.

    PubMed

    Couchman, Kiri; Grothe, Benedikt; Felmy, Felix

    2012-02-01

    Neurons of the medial superior olive (MSO) code for the azimuthal location of low-frequency sound sources via a binaural coincidence detection system operating on microsecond time scales. These neurons are morphologically simple and stereotyped, and anatomical studies have indicated a functional segregation of excitatory and inhibitory inputs between cellular compartments. It is thought that this morphological arrangement holds important implications for the computational task of these cells. To date, however, there has been no functional investigation into synaptic input sites or functional receptor distributions on mature neurons of the MSO. Here, functional neurotransmitter receptor maps for amino-3-hydroxyl-5-methyl-4-isoxazole propionate (AMPA), N-methyl-D-aspartate (NMDA), glycine (Gly), and ionotropic γ-aminobutyric acid (GABA(A)) receptors (Rs) were compared and complemented by their corresponding synaptic input map. We find in MSO neurons from postnatal day 20-35 gerbils that AMPARs and their excitatory inputs target the soma and dendrites. Functional GlyRs and their inhibitory inputs are predominantly refined to the somata, although a pool of functional GlyRs is present extrasynaptically on MSO dendrites. GABA(A)R responses are present throughout the cell but lack direct synaptic contact indicating an involvement in volume transmission. NMDARs are present both synaptically and extrasynaptically with an overall distribution similar to GlyRs. Interestingly, even at physiological temperatures these functional NMDARs can be potentiated by synaptically released Gly. The functional receptor and synaptic input maps produced here led to the identification of a cross talk between transmitter systems and raises the possibility that extrasynaptic receptors could be modulating leak conductances as a homeostatic mechanism.

  15. Role of astrocytic glutamate transporter in alcohol use disorder

    PubMed Central

    Ayers-Ringler, Jennifer R; Jia, Yun-Fang; Qiu, Yan-Yan; Choi, Doo-Sup

    2016-01-01

    Alcohol use disorder (AUD) is one of the most widespread neuropsychiatric conditions, having a significant health and socioeconomic impact. According to the 2014 World Health Organization global status report on alcohol and health, the harmful use of alcohol is responsible for 5.9% of all deaths worldwide. Additionally, 5.1% of the global burden of disease and injury is ascribed to alcohol (measured in disability adjusted life years, or disability adjusted life years). Although the neurobiological basis of AUD is highly complex, the corticostriatal circuit contributes significantly to the development of addictive behaviors. In-depth investigation into the changes of the neurotransmitters in this circuit, dopamine, gamma-aminobutyricacid, and glutamate, and their corresponding neuronal receptors in AUD and other addictions enable us to understand the molecular basis of AUD. However, these discoveries have also revealed a dearth of knowledge regarding contributions from non-neuronal sources. Astrocytes, though intimately involved in synaptic function, had until recently been noticeably overlooked in their potential role in AUD. One major function of the astrocyte is protecting neurons from excitotoxicity by removing glutamate from the synapse via excitatory amino acid transporter type 2. The importance of this key transporter in addiction, as well as ethanol withdrawal, has recently become evident, though its regulation is still under investigation. Historically, pharmacotherapy for AUD has been focused on altering the activity of neuronal glutamate receptors. However, recent clinical evidence has supported the animal-based findings, showing that regulating glutamate homeostasis contributes to successful management of recovery from AUD. PMID:27014596

  16. Cloning and expression of a rat brain GABA transporter

    SciTech Connect

    Guastella, J.; Czyzyk, L.; Davidson, N.; Lester, H.A. ); Nelson, N.; Nelson, H.; Miedel, M.C. ); Keynan, S.; Kanner, B.I. )

    1990-09-14

    A complementary DNA clone (designated GAT-1) encoding a transporter for the neurotransmitter {gamma}-aminobutyric acid (GABA) has been isolated from rat brain, and its functional properties have been examined in Xenopus oocytes. Oocytes injected with GAT-1 synthetic messenger RNA accumulated ({sup 3}H)GABA to levels above control values. The transporter encoded by GAT-1 has a high affinity for GABA, is sodium- and chloride-dependent, and is pharmacologically similar to neuronal GABA transporters. The GAT-1 protein shares antigenic determinants with a native rat brain GABA transporter. The nucleotide sequence of GAT-1 predicts a protein of 599 amino acids with a molecular weight of 67 kilodaltons. Hydropathy analysis of the deduced protein suggests multiple transmembrane regions, a feature shared by several cloned transporters; however, database searches indicate that GAT-1 is not homologous to any previously identified proteins. Therefore, GAT-1 appears to be a member of a previously uncharacterized family of transport molecules.

  17. Focused ultrasound in ophthalmology

    PubMed Central

    Silverman, Ronald H

    2016-01-01

    The use of focused ultrasound to obtain diagnostically significant information about the eye goes back to the 1950s. This review describes the historical and technological development of ophthalmic ultrasound and its clinical application and impact. Ultrasound, like light, can be focused, which is crucial for formation of high-resolution, diagnostically useful images. Focused, single-element, mechanically scanned transducers are most common in ophthalmology. Specially designed transducers have been used to generate focused, high-intensity ultrasound that through thermal effects has been used to treat glaucoma (via ciliodestruction), tumors, and other pathologies. Linear and annular transducer arrays offer synthetic focusing in which precise timing of the excitation of independently addressable array elements allows formation of a converging wavefront to create a focus at one or more programmable depths. Most recently, linear array-based plane-wave ultrasound, in which the array emits an unfocused wavefront and focusing is performed solely on received data, has been demonstrated for imaging ocular anatomy and blood flow. While the history of ophthalmic ultrasound extends back over half-a-century, new and powerful technologic advances continue to be made, offering the prospect of novel diagnostic capabilities. PMID:27757007

  18. Focused ultrasound in ophthalmology.

    PubMed

    Silverman, Ronald H

    2016-01-01

    The use of focused ultrasound to obtain diagnostically significant information about the eye goes back to the 1950s. This review describes the historical and technological development of ophthalmic ultrasound and its clinical application and impact. Ultrasound, like light, can be focused, which is crucial for formation of high-resolution, diagnostically useful images. Focused, single-element, mechanically scanned transducers are most common in ophthalmology. Specially designed transducers have been used to generate focused, high-intensity ultrasound that through thermal effects has been used to treat glaucoma (via ciliodestruction), tumors, and other pathologies. Linear and annular transducer arrays offer synthetic focusing in which precise timing of the excitation of independently addressable array elements allows formation of a converging wavefront to create a focus at one or more programmable depths. Most recently, linear array-based plane-wave ultrasound, in which the array emits an unfocused wavefront and focusing is performed solely on received data, has been demonstrated for imaging ocular anatomy and blood flow. While the history of ophthalmic ultrasound extends back over half-a-century, new and powerful technologic advances continue to be made, offering the prospect of novel diagnostic capabilities.

  19. A comprehensive structure-based alignment of prokaryotic and eukaryotic neurotransmitter/Na+ symporters (NSS) aids in the use of the LeuT structure to probe NSS structure and function.

    PubMed

    Beuming, Thijs; Shi, Lei; Javitch, Jonathan A; Weinstein, Harel

    2006-11-01

    The recently elucidated crystal structure of a prokaryotic member of the neurotransmitter/sodium symporter (NSS) family (Yamashita et al., 2005) is a major advance toward understanding structure-function relationships in this important class of transporters. To aid in the generalization of these results, we present here a comprehensive sequence alignment of all known prokaryotic and eukaryotic NSS proteins, based on the crystal structure of the leucine transporter from Aquifex aeolicus (LeuT). Regions of low sequence identity between prokaryotic and eukaryotic transporters were aligned with the aid of a number of bioinformatics tools, and the resulting alignments were validated by comparison with experimental data. In a number of regions, including the transmembrane segments 4, 5, and 9 as well as extracellular loops 2, 3, and 4, our alignment differs from the one proposed previously [Nature (Lond) 437: 215-223, 2005]. Important similarities and differences among the sequences of NSS proteins in regions likely to determine selectivity in substrate binding and mechanisms of transport regulation are discussed in the context of the LeuT structure and the alignment.

  20. Flat Focusing Mirror

    PubMed Central

    Cheng, Y. C.; Kicas, S.; Trull, J.; Peckus, M.; Cojocaru, C.; Vilaseca, R.; Drazdys, R.; Staliunas, K.

    2014-01-01

    The control of spatial propagation properties of narrow light beams such as divergence, focusing or imaging are main objectives in optics and photonics. In this letter, we propose and demonstrate experimentally a flat focusing mirror, based on an especially designed dielectric structure without any optical axis. More generally, it also enables imaging any light pattern in reflection. The flat focusing mirror with a transversal invariance can largely increase the applicability of structured photonic materials for light beam propagation control in small-dimension photonic circuits. PMID:25228358

  1. Convergent and reciprocal modulation of a leak K+ current and Ih by an inhalational anaesthetic and neurotransmitters in rat brainstem motoneurones

    PubMed Central

    Sirois, Jay E; Lynch, Carl; Bayliss, Douglas A

    2002-01-01

    Neurotransmitters and volatile anaesthetics have opposing effects on motoneuronal excitability which appear to reflect contrasting modulation of two types of subthreshold currents. Neurotransmitters increase motoneuronal excitability by inhibiting TWIK-related acid-sensitive K+ channels (TASK) and shifting activation of a hyperpolarization-activated cationic current (Ih) to more depolarized potentials; on the other hand, anaesthetics decrease excitability by activating a TASK-like current and inducing a hyperpolarizing shift in Ih activation. Here, we used whole-cell recording from motoneurones in brainstem slices to test if neurotransmitters (serotonin (5-HT) and noradrenaline (NA)) and an anaesthetic (halothane) indeed compete for modulation of the same ion channels - and we determined which prevails. When applied together under current clamp conditions, 5-HT reversed anaesthetic-induced membrane hyperpolarization and increased motoneuronal excitability. Under voltage clamp conditions, 5-HT and NA overcame most, but not all, of the halothane-induced current. When Ih was blocked with ZD 7288, the neurotransmitters completely inhibited the K+ current activated by halothane; the halothane-sensitive neurotransmitter current reversed at the equilibrium potential for potassium (EK) and displayed properties expected of acid-sensitive, open-rectifier TASK channels. To characterize modulation of Ih in relative isolation, effects of 5-HT and halothane were examined in acidified bath solutions that blocked TASK channels. Under these conditions, 5-HT and halothane each caused their characteristic shift in voltage-dependent gating of Ih. When tested concurrently, however, halothane decreased the neurotransmitter-induced depolarizing shift in Ih activation. Thus, halothane and neurotransmitters converge on TASK and Ih channels with opposite effects; transmitter action prevailed over anaesthetic effects on TASK channels, but not over effects on Ih. These data suggest that

  2. Facility Focus: Food Service.

    ERIC Educational Resources Information Center

    College Planning & Management, 2002

    2002-01-01

    Describes the Hawthorn Court Community Center at Iowa State University, Ames, and the HUB-Robeson Center at Pennsylvania State University. Focuses on the food service offered in these new student-life buildings. Includes photographs. (EV)

  3. Focusing corner cube

    DOEpatents

    Monjes, J.A.

    1985-09-12

    This invention retortreflects and focuses a beam of light. The invention comprises a modified corner cube reflector wherein one reflective surface is planar, a second reflective surface is spherical, and the third reflective surface may be planar or convex cylindrical.

  4. Inertial Focusing in Microfluidics

    PubMed Central

    Martel, Joseph M.; Toner, Mehmet

    2015-01-01

    When Segré and Silberberg in 1961 witnessed particles in a laminar pipe flow congregating at an annulus in the pipe, scientists were perplexed and spent decades learning why such behavior occurred, finally understanding that it was caused by previously unknown forces on particles in an inertial flow. The advent of microfluidics opened a new realm of possibilities for inertial focusing in the processing of biological fluids and cellular suspensions and created a field that is now rapidly expanding. Over the past five years, inertial focusing has enabled high-throughput, simple, and precise manipulation of bodily fluids for a myriad of applications in point-of-care and clinical diagnostics. This review describes the theoretical developments that have made the field of inertial focusing what it is today and presents the key applications that will make inertial focusing a mainstream technology in the future. PMID:24905880

  5. Inertial focusing in microfluidics.

    PubMed

    Martel, Joseph M; Toner, Mehmet

    2014-07-11

    When Segré and Silberberg in 1961 witnessed particles in a laminar pipe flow congregating at an annulus in the pipe, scientists were perplexed and spent decades learning why such behavior occurred, finally understanding that it was caused by previously unknown forces on particles in an inertial flow. The advent of microfluidics opened a new realm of possibilities for inertial focusing in the processing of biological fluids and cellular suspensions and created a field that is now rapidly expanding. Over the past five years, inertial focusing has enabled high-throughput, simple, and precise manipulation of bodily fluids for a myriad of applications in point-of-care and clinical diagnostics. This review describes the theoretical developments that have made the field of inertial focusing what it is today and presents the key applications that will make inertial focusing a mainstream technology in the future.

  6. Final focus nomenclature

    SciTech Connect

    Erickson, R.

    1986-08-08

    The formal names and common names for all devices in the final focus system of the SLC are listed. The formal names consist of a device type designator, microprocessor designator, and a four-digit unit number. (LEW)

  7. Final focus test beam

    SciTech Connect

    Not Available

    1991-03-01

    This report discusses the following: the Final Focus Test Beam Project; optical design; magnets; instrumentation; magnetic measurement and BPM calibration; mechanical alignment and stabilization; vacuum system; power supplies; control system; radiation shielding and personnel protection; infrastructure; and administration.

  8. Electron beam focusing system

    SciTech Connect

    Dikansky, N.; Nagaitsev, S.; Parkhomchuk, V.

    1997-09-01

    The high energy electron cooling requires a very cold electron beam. Thus, the electron beam focusing system is very important for the performance of electron cooling. A system with and without longitudinal magnetic field is presented for discussion. Interaction of electron beam with the vacuum chamber as well as with the background ions and stored antiprotons can cause the coherent electron beam instabilities. Focusing system requirements needed to suppress these instabilities are presented.

  9. New NLC Final Focus

    SciTech Connect

    Raimondi, P.

    2004-10-11

    A novel design of the Final Focus has recently been proposed [1] and has been adopted now for the Next Linear Collider [2]. This new design has fewer optical elements and is much shorter, nonetheless achieving better chromatic properties. In this paper, the new final focus system is briefly discussed stressing one particular characteristic of the new design--its multi TeV energy reach.

  10. Plutonium focus area

    SciTech Connect

    1996-08-01

    To ensure research and development programs focus on the most pressing environmental restoration and waste management problems at the U.S. Department of Energy (DOE), the Assistant Secretary for the Office of Environmental Management (EM) established a working group in August 1993 to implement a new approach to research and technology development. As part of this new approach, EM developed a management structure and principles that led to the creation of specific Focus Areas. These organizations were designed to focus the scientific and technical talent throughout DOE and the national scientific community on the major environmental restoration and waste management problems facing DOE. The Focus Area approach provides the framework for intersite cooperation and leveraging of resources on common problems. After the original establishment of five major Focus Areas within the Office of Technology Development (EM-50, now called the Office of Science and Technology), the Nuclear Materials Stabilization Task Group (EM-66) followed the structure already in place in EM-50 and chartered the Plutonium Focus Area (PFA). The following information outlines the scope and mission of the EM, EM-60, and EM-66 organizations as related to the PFA organizational structure.

  11. Salvinorin A exerts opposite presynaptic controls on neurotransmitter exocytosis from mouse brain nerve terminals.

    PubMed

    Grilli, Massimo; Neri, Elisa; Zappettini, Stefania; Massa, Francesca; Bisio, Angela; Romussi, Giovanni; Marchi, Mario; Pittaluga, Anna

    2009-01-01

    We investigated the effects of salvinorin A on the basal and the 12 mM K(+)-evoked release of preloaded [(3)H]noradenaline ([(3)H]NA) and [(3)H]serotonin ([(3)H]5-HT) from mouse hippocampal nerve terminals (synaptosomes), as well as on the basal and 12mM K(+)-evoked release of preloaded [(3)H]dopamine ([(3)H]DA) from mouse striatal and prefrontal cortex (PFc) synaptosomes. Salvinorin A (0.1-1000 nM) failed to affect the basal release of amines, but inhibited the 12 mM K(+)-evoked, Ca(2+)-dependent, exocytotic-like release of [(3)H]5-HT and [(3)H]DA. At the same concentration, salvinorin A facilitated the 12 mM K(+)-evoked, Ca(2+)-dependent, exocytotic-like release of [(3)H]NA. These effects could not be observed in pertussis toxin (PTx) entrapped synaptosomes. The broad spectrum kappa-opioid receptor (KOR) antagonist norbinaltorphimine (norBNI, 1-100 nM) antagonized the inhibition of [(3)H]5-HT and [(3)H]DA exocytosis as well as the facilitation of [(3)H]NA overflow induced by 100 nM salvinorin A. The KOR agonist U69593 (1-100 nM) mimicked salvinorin A in inhibiting [(3)H]5-HT and of [(3)H]DA exocytosis, its effect being prevented by norBNI, but leaving unchanged the K(+)-evoked release of [(3)H]NA. The effects of Salvinorin A on neurotransmitter exocytosis were not prevented by the selective mu opioid (MOR) receptor antagonist CTAP (10-100 nM), whereas facilitation of [(3)H]NA exocytosis, but not inhibition of [(3)H]5-HT and [(3)H]DA K(+)-evoked release, was counteracted by the delta opioid receptor (DOR) antagonist naltrindole (1-100 nM). We conclude that salvinorin A presynaptically modulates central NA, 5-HT, and DA exocytosis evoked by a mild depolarizing stimulus by acting at presynaptic opioid receptors having different pharmacological profiles.

  12. Analysis of neurotransmitter distribution in brain development of benthic and pelagic octopod cephalopods.

    PubMed

    Wollesen, Tim; Sukhsangchan, Charuay; Seixas, Pedro; Nabhitabhata, Jaruwat; Wanninger, Andreas

    2012-07-01

    The database on neurotransmitter distribution during central nervous system development of cephalopod mollusks is still scarce. We describe the ontogeny of serotonergic (5-HT-ir) and FMRFamide-like immunoreactive (Fa-lir) neurons in the central nervous system of the benthic Octopus vulgaris and Fa-lir distribution in the pelagic Argonauta hians. Comparing our data to previous studies, we aim at revealing shared immunochemical domains among coleoid cephalopods, i.e., all cephalopods except nautiluses. During development of O. vulgaris, 5-HT-ir and Fa-lir elements occur relatively late, namely during stage XII, when the brain neuropils are already highly differentiated. In stage XII-XX individuals, Fa-lir cell somata are located in the middle and posterior subesophageal mass and in the optic, posterior basal, and superior buccal lobes. 5-HT is predominately expressed in cell somata of the superior buccal, anterior basal, and optic lobes, as well as in the subesophageal mass. The overall population of Fa-lir neurons is larger than the one expressing 5-HT. Fa-lir elements are distributed throughout homologous brain areas of A. hians and O. vulgaris. We identified neuronal subsets with similar cell number and immunochemical phenotype in coleoids. These are located in corresponding brain regions of developmental stages and adults of O. vulgaris, A. hians, and the decapod squid Idiosepius notoides. O. vulgaris and I. notoides exhibit numerous 5-HT-ir cell somata in the superior buccal lobes but none or very few in the inferior buccal lobes. The latter have previously been homologized to the gastropod buccal ganglia, which also lack 5-HT-ir cell somata in euthyneuran gastropods. Among coleoids, 5-HT-ir neuronal subsets, which are located ventrally to the lateral anterior basal lobes and in the anterior middle subesophageal mass, are candidates for homologous subsets. Contrary to I. notoides, octopods exhibit Fa-lir cell somata ventrally to the brachial lobes and 5-HT

  13. Fluorine Substitution in Neurotransmitters: Microwave Spectroscopy and Modelling of the Conformational Space and Non Bonding Interactions

    NASA Astrophysics Data System (ADS)

    Melandri, S.; Maris, A.; Merloni, A.

    2011-06-01

    Fluorine substitution in molecules is a common practice in bio-organic chemistry in order to modulate physicochemical properties and biological activity of molecules and an increasing number of drugs on the market contain fluorine, the presence of which is often of major importance to modify pharmacokinetics properties and molecular activity. The rationale for such a strategy is that fluorine is generally a stronger electron acceptor than the other halogen atoms and its size is intermediate between that of hydrogen and oxygen. We have studied two fluorinated analogs of 2-phenylethylamine (PEA), the prototype molecule for adrenergic neurotransmitters, namely: 4-Fluoro (4FPEA) and 2-Fluoro-2-phenylethylamine (2FPEA) by Molecular Beam Fourier Transform Microwave Spectroscopy in the frequency range 6-18 GHz and ab initio calculations at the MP2/6311++G** level. The aim is to obtain information on the spatial arrangement of the ethylamine side chain and the effects of fluorination on the energy landscape. The conformational space is dominated by low energy gauche conformations stabilized by weak interactions between the aminic hydrogens and the electron cloud of the benzene ring and anti conformations higher in energy. In 2FPEA the presence of the fluorine atom almost duplicate the number of possible conformation with respect to 4FPEA. We observed two conformers of 4FPEA and five conformers of 2FPEA which have been classified with the guide provided by accurate ab initio calculations. The identification of the conformational species was helped by the analysis of the quadrupole hyperfine pattern which is greatly influenced by the orientation of the amino group and acts as a fingerprint for each conformation. The orientation of the dipole moment within the principal axis frame and the order of stability of the different conformations are other independent pieces of evidence for the unambiguous assignment and identification of the conformers. The order of stability was

  14. EDITORIAL: Focus on Plasmonics FOCUS ON PLASMONICS

    NASA Astrophysics Data System (ADS)

    Bozhevolnyi, Sergey; García-Vidal, Francisco

    2008-10-01

    Plasmonics is an emerging field in optics dealing with the so-called surface plasmons whose extraordinary properties are being both analyzed from a fundamental point of view and exploited for numerous technological applications. Surface plasmons associated with surface electron density oscillations decorating metal-dielectric interfaces were discovered by Rufus Ritchie in the 1950s. Since the seventies, the subwavelength confinement of electromagnetic fields as well as their enhancement inherent to the surface plasmon excitation has been widely used for spectroscopic purposes. Recent advances in nano-fabrication, characterization and modelling techniques have allowed unique properties of these surface electromagnetic modes to be explored with respect to subwavelength field localization and waveguiding, opening the path to truly nanoscale plasmonic optical devices. This area of investigation also has interesting links with research on photonic band gap materials and the field of optical metamaterials. Nowadays, plasmonics can be seen as a mature interdisciplinary area of research in which scientists coming from different backgrounds (chemistry, physics, optics and engineering) strive to discover and exploit new and exciting phenomena associated with surface plasmons. The already made and forthcoming discoveries will have impacts in many fields of science and technology, including not only photonics and materials science but also computation, biology and medicine, among others. This focus issue of New Journal of Physics is intended to cover all the aforementioned capabilities of surface plasmons by presenting a current overview of state-of-the-art advances achieved by the leading groups in this field of research. The below list of articles represents the first contributions to the collection and further additions will appear soon. Focus on Plasmonics Contents Nanoantenna array-induced fluorescence enhancement and reduced lifetimes Reuben M Bakker, Vladimir P Drachev

  15. Radiation Transport

    SciTech Connect

    Urbatsch, Todd James

    2015-06-15

    We present an overview of radiation transport, covering terminology, blackbody raditation, opacities, Boltzmann transport theory, approximations to the transport equation. Next we introduce several transport methods. We present a section on Caseology, observing transport boundary layers. We briefly broach topics of software development, including verification and validation, and we close with a section on high energy-density experiments that highlight and support radiation transport.

  16. Final focus systems for linear colliders

    SciTech Connect

    Erickson, R.A.

    1987-11-01

    The final focus system of a linear collider must perform two primary functions, it must focus the two opposing beams so that their transverse dimensions at the interaction point are small enough to yield acceptable luminosity, and it must steer the beams together to maintain collisions. In addition, the final focus system must transport the outgoing beams to a location where they can be recycled or safely dumped. Elementary optical considerations for linear collider final focus systems are discussed, followed by chromatic aberrations. The design of the final focus system of the SLAC Linear Collider (SLC) is described. Tuning and diagnostics and steering to collision are discussed. Most of the examples illustrating the concepts covered are drawn from the SLC, but the principles and conclusions are said to be generally applicable to other linear collider designs as well. 26 refs., 17 figs. (LEW)

  17. NICMOS focus monitor

    NASA Astrophysics Data System (ADS)

    Schneider, Glenn

    1997-07-01

    This proposal is used to determine and monitor the optimal focus and tilt settings for all three NICMOS cameras. It is derived from SM2/NIC 7041, but is structurally quite a bit different. This proposal is built to run NIC1/2 focus sweeps on a weekly basis, and NIC3 focus sweeps twice a week during SMOV {following the "interim" runs of the 7150}. 7043 will run for as long as it is deemed necessary to keep track of the camera focii and to monitor the dewar anomaly. After the discussion on 20/3/96, this proposal is written to run 4 complete 1-week iterations starting 3 days after the last run of the 7150 {NICMOS COARSE OPTICAL ALIGNMENT, PART 2}.

  18. Sagittal focusing Laue monochromator

    DOEpatents

    Zhong; Zhong , Hanson; Jonathan , Hastings; Jerome , Kao; Chi-Chang , Lenhard; Anthony , Siddons; David Peter , Zhong; Hui

    2009-03-24

    An x-ray focusing device generally includes a slide pivotable about a pivot point defined at a forward end thereof, a rail unit fixed with respect to the pivotable slide, a forward crystal for focusing x-rays disposed at the forward end of the pivotable slide and a rearward crystal for focusing x-rays movably coupled to the pivotable slide and the fixed rail unit at a distance rearward from the forward crystal. The forward and rearward crystals define reciprocal angles of incidence with respect to the pivot point, wherein pivoting of the slide about the pivot point changes the incidence angles of the forward and rearward crystals while simultaneously changing the distance between the forward and rearward crystals.

  19. Decontamination & decommissioning focus area

    SciTech Connect

    1996-08-01

    In January 1994, the US Department of Energy Office of Environmental Management (DOE EM) formally introduced its new approach to managing DOE`s environmental research and technology development activities. The goal of the new approach is to conduct research and development in critical areas of interest to DOE, utilizing the best talent in the Department and in the national science community. To facilitate this solutions-oriented approach, the Office of Science and Technology (EM-50, formerly the Office of Technology Development) formed five Focus AReas to stimulate the required basic research, development, and demonstration efforts to seek new, innovative cleanup methods. In February 1995, EM-50 selected the DOE Morgantown Energy Technology Center (METC) to lead implementation of one of these Focus Areas: the Decontamination and Decommissioning (D & D) Focus Area.

  20. [Focused musculoskeletal sonography].

    PubMed

    Horn, Rudolf

    2015-09-16

    Even in emergent situations, focused musculoskeletal sonography must not be overlooked. It has a place in traumatology no less valuable than its place in internal medicine. It can be used to identify traumatic joint effusions, occult fractures and fissures, joint inflammation, muscle and tendon rupture; it can differentiate soft tissue swelling, locate a foreign body, or identify the location of fractures. Focused ultrasound should be performed by the attending physician directly at the patient’s bedside, in order to answer these specific questions.