The Experts below are selected from a list of 17271 Experts worldwide ranked by ideXlab platform
Nancy R Zahniser - One of the best experts on this subject based on the ideXlab platform.
-
rapid regulation of dopamine transporter function by substrates blockers and Presynaptic Receptor ligands
European Journal of Pharmacology, 2003Co-Authors: Joshua M Gulley, Nancy R ZahniserAbstract:Abstract The extracellular actions of dopamine are terminated primarily through its binding to dopamine transporters and translocation back into dopamine neurons. The transporter thereby serves as an optimal target to regulate dopamine neurotransmission. Although acute pharmacological blockade of dopamine transporters is known to reversibly inhibit transporter function by preventing the binding of its endogenous substrate dopamine, it recently has become clear that dopamine transporter substrates, such as amphetamines, and blockers, such as cocaine, also have the ability to rapidly and persistently regulate transporter function after their direct pharmacological effect has subsided. Presynaptic Receptor ligands can also regulate dopamine transporter function. This has been investigated most extensively for dopamine D2 Receptors, but there is also evidence for regulation by γ-aminobutyric acid (GABA) GABAB Receptors, metabotropic glutamate, nicotinic acetylcholine, serotonin, σ2- and κ-opioid Receptors. The focus of this review is the rapid, typically reversible, regulation of dopamine transporter velocity by substrates, blockers and Presynaptic Receptor ligands. The research discussed here suggests that a common mechanism through which these different classes of compounds regulate transporter activity is by altering the cell surface expression of dopamine transporters.
-
chronic and acute regulation of na cl dependent neurotransmitter transporters drugs substrates Presynaptic Receptors and signaling systems
Pharmacology & Therapeutics, 2001Co-Authors: Nancy R Zahniser, Suzanne DoolenAbstract:Na+/Cl- -dependent neurotransmitter transporters, which constitute a gene superfamily, are crucial for limiting neurotransmitter activity. Thus, it is critical to understand their regulation. This review focuses primarily on the norepinephrine transporter, the dopamine transporter, the serotonin transporter, and the gamma-aminobutyric acid transporter GAT1. Chronic administration of drugs that alter neurotransmitter release or inhibit transporter activity can produce persistent compensatory changes in brain transporter number and activity. However, regulation has not been universally observed. Transient alterations in norepinephrine transporter, dopamine transporter, serotonin transporter, and GAT1 function and/or number occur in response to more acute manipulations, including membrane potential changes, substrate exposure, ethanol exposure, and Presynaptic Receptor activation/inhibition. In many cases, acute regulation has been shown to result from a rapid redistribution of the transporter between the cell surface and intracellular sites. Second messenger systems involved in this rapid regulation include protein kinases and phosphatases, of which protein kinase C has been the best characterized. These signaling systems share the common characteristic of altering maximal transport velocity and/or cell surface expression, consistent with regulation of transporter trafficking. Although less well characterized, arachidonic acid, reactive oxygen species, and nitric oxide also alter transporter function. In addition to post-translational modifications, cytoskeleton interactions and transporter oligomerization regulate transporter activity and trafficking. Furthermore, promoter regions involved in transporter transcriptional regulation have begun to be identified. Together, these findings suggest that Na+/Cl- -dependent neurotransmitter transporters are regulated both long-term and in a more dynamic manner, thereby providing several distinct mechanisms for altering synaptic neurotransmitter concentrations and neurotransmission.
Joshua M Gulley - One of the best experts on this subject based on the ideXlab platform.
-
rapid regulation of dopamine transporter function by substrates blockers and Presynaptic Receptor ligands
European Journal of Pharmacology, 2003Co-Authors: Joshua M Gulley, Nancy R ZahniserAbstract:Abstract The extracellular actions of dopamine are terminated primarily through its binding to dopamine transporters and translocation back into dopamine neurons. The transporter thereby serves as an optimal target to regulate dopamine neurotransmission. Although acute pharmacological blockade of dopamine transporters is known to reversibly inhibit transporter function by preventing the binding of its endogenous substrate dopamine, it recently has become clear that dopamine transporter substrates, such as amphetamines, and blockers, such as cocaine, also have the ability to rapidly and persistently regulate transporter function after their direct pharmacological effect has subsided. Presynaptic Receptor ligands can also regulate dopamine transporter function. This has been investigated most extensively for dopamine D2 Receptors, but there is also evidence for regulation by γ-aminobutyric acid (GABA) GABAB Receptors, metabotropic glutamate, nicotinic acetylcholine, serotonin, σ2- and κ-opioid Receptors. The focus of this review is the rapid, typically reversible, regulation of dopamine transporter velocity by substrates, blockers and Presynaptic Receptor ligands. The research discussed here suggests that a common mechanism through which these different classes of compounds regulate transporter activity is by altering the cell surface expression of dopamine transporters.
Katsuhiko Tabuchi - One of the best experts on this subject based on the ideXlab platform.
-
ptpσ functions as a Presynaptic Receptor for the glypican 4 lrrtm4 complex and is essential for excitatory synaptic transmission
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Ji Seung Ko, Giuseppe Condomitti, Gopal Pramanik, Ji Won Um, Ji Seon Shim, Gugyoung Chung, Kangsik Park, Katsuhiko TabuchiAbstract:Leukocyte common antigen-related Receptor protein tyrosine phosphatases—comprising LAR, PTPδ, and PTPσ—are synaptic adhesion molecules that organize synapse development. Here, we identify glypican 4 (GPC-4) as a ligand for PTPσ. GPC-4 showed strong (nanomolar) affinity and heparan sulfate (HS)-dependent interaction with the Ig domains of PTPσ. PTPσ bound only to proteolytically cleaved GPC-4 and formed additional complex with leucine-rich repeat transmembrane protein 4 (LRRTM4) in rat brains. Moreover, single knockdown (KD) of PTPσ, but not LAR, in cultured neurons significantly reduced the synaptogenic activity of LRRTM4, a postsynaptic ligand of GPC-4, in heterologous synapse-formation assays. Finally, PTPσ KD dramatically decreased both the frequency and amplitude of excitatory synaptic transmission. This effect was reversed by wild-type PTPσ, but not by a HS-binding–defective PTPσ mutant. Our results collectively suggest that Presynaptic PTPσ, together with GPC-4, acts in a HS-dependent manner to maintain excitatory synapse development and function.
Nadim Farah - One of the best experts on this subject based on the ideXlab platform.
-
Ação da peçonha de Micrurus surinamensis na junção neuromuscular e no musculo esqueletico
[s.n.], 2018Co-Authors: Heluany Sobrinho, Nadim FarahAbstract:Orientador: Oswaldo Vital BrazilTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O veneno da Micrurus surinamensis, uma cobra coral da região amazônica, induz bloqueio neuromuscular nas preparações nervo frênico-diafragma de rato e nervo-músculo biventer cervicis de pintos. o veneno deprime a tensão das respostas do diafragma à estimulação direta, não deprimindo, entretanto, a do biventer cervicis. Deve conter uma ou mais toxinas pós-sinápticas curaremiméticas, uma vez que os potenciais de placa terminal em miniatura (ps.p.t.m.) bloqueados pelo veneno reapareceram após a adição da neostigmina ao banho. Deve haver também no veneno toxina ou toxinas que induzem a dessensibilização do Receptor da placa terminal, fato demonstrado pelo efeito antagônico da 4-aminopiridina (4-AP) sobre o bloqueio dos ps.p.t.m. induzido pelo veneno. A reversibilidade e o efeito antagônico da neostigmina e da 3,4-diaminopiridina (3,4-DAP) apenas parciais nas preparações nervo frênico-diafragma de rato e biventer-cervicis de pintos sugere a presença de neurotoxina pós-sináptica irreversível ou de neurotoxinas pré-sinápticas no veneno. A ação contraturante do veneno, mais evidente no músculo biventer-cervicis de pintos, não abolida pela curarização da preparação mas suprimida pela elevação da concentração de cálcio na solução nutritiva ou adição de sulfato de magnésio (MgSO4), e a ação despolarizante das membranas das fibras do diafragma mostram que o veneno contém constituintes de ação semelhante à das cardiotoxinas. Portanto, os efeitos neuromusculares e miotóxico do veneno de M. surinamensis resultam de ações de um conjunto de toxinas, que ocorrem em outros venenos de cobras corais. É a primeira vez que ações semelhantes à das cardiotoxinas é identificada em espécies de Micrurus sul-americanaAbstract: Micrurus surinamensis occurs in the Amazon valley and upper Negro and Orinoco rivers. The distribution includes the countries Ecuador, Peru, Colombia, Brazil, Venezuela and the Guianas. M. surinamensis venom produces neuromuscular blockade in the rat phrenic nerve-diaphragm and in the chick biventer-cervicis nerve muscle preparations. It induces depression of the twitches elicited by direct muscle stimulation in the curarized rat diaphragm. In denervated hemidiaphragm of the rat, the contracture produced by acetylcholine (Ach) is blocked by the venom. Ach and carbachol-induced responses are also inhibited in chick biventer-cervicis muscle while the contracture produced by is increased. The blockade of the miniature end-plate potenciais (m.e.p.ps.) induced by M. surinamensis venom in the rat diaphragm is antagonized by neostigmine and by 4 aminopyridine. M. surinamensis venom causes depolarization of the rat diaphragm muscle fibers. It induces contracture of the rat diaphragm and biventer cervicis, the contracture being more intense in the last muscle. It is also produced in curarized muscles and in muscles treated with tetrodotoxin. On the other hand, calcium excess (Krebbs solution with 10 mM CaCb) blocks the venom-induced contracture. These results show that M. surinamensis venom contains reversible curaremimetic toxin(s) and toxin(s) that induces desensitization of the end-plate nicotinic Receptor. They also show that it contains cardiotoxin-like toxin(s). Some results (increase of twitch tension before blockade, irreversibility of the neuromuscular blockade) suggest that Presynaptic Receptor toxins and irreversible curaremimetic toxins are contained in the M. surinamenis venomDoutoradoFarmacologia, Anestesiologia e TerapeuticaDoutor em Odontologi
Nadim Farah Heluany Sobrinho - One of the best experts on this subject based on the ideXlab platform.
-
Ação da peçonha de Micrurus surinamensis na junção neuromuscular e no musculo esqueletico
2017Co-Authors: Nadim Farah Heluany SobrinhoAbstract:Resumo: O veneno da Micrurus surinamensis, uma cobra coral da região amazônica, induz bloqueio neuromuscular nas preparações nervo frênico-diafragma de rato e nervo-músculo biventer cervicis de pintos. o veneno deprime a tensão das respostas do diafragma à estimulação direta, não deprimindo, entretanto, a do biventer cervicis. Deve conter uma ou mais toxinas pós-sinápticas curaremiméticas, uma vez que os potenciais de placa terminal em miniatura (ps.p.t.m.) bloqueados pelo veneno reapareceram após a adição da neostigmina ao banho. Deve haver também no veneno toxina ou toxinas que induzem a dessensibilização do Receptor da placa terminal, fato demonstrado pelo efeito antagônico da 4-aminopiridina (4-AP) sobre o bloqueio dos ps.p.t.m. induzido pelo veneno. A reversibilidade e o efeito antagônico da neostigmina e da 3,4-diaminopiridina (3,4-DAP) apenas parciais nas preparações nervo frênico-diafragma de rato e biventer-cervicis de pintos sugere a presença de neurotoxina pós-sináptica irreversível ou de neurotoxinas pré-sinápticas no veneno. A ação contraturante do veneno, mais evidente no músculo biventer-cervicis de pintos, não abolida pela curarização da preparação mas suprimida pela elevação da concentração de cálcio na solução nutritiva ou adição de sulfato de magnésio (MgSO4), e a ação despolarizante das membranas das fibras do diafragma mostram que o veneno contém constituintes de ação semelhante à das cardiotoxinas. Portanto, os efeitos neuromusculares e miotóxico do veneno de M. surinamensis resultam de ações de um conjunto de toxinas, que ocorrem em outros venenos de cobras corais. É a primeira vez que ações semelhantes à das cardiotoxinas é identificada em espécies de Micrurus sul-americanaAbstract: Micrurus surinamensis occurs in the Amazon valley and upper Negro and Orinoco rivers. The distribution includes the countries Ecuador, Peru, Colombia, Brazil, Venezuela and the Guianas. M. surinamensis venom produces neuromuscular blockade in the rat phrenic nerve-diaphragm and in the chick biventer-cervicis nerve muscle preparations. It induces depression of the twitches elicited by direct muscle stimulation in the curarized rat diaphragm. In denervated hemidiaphragm of the rat, the contracture produced by acetylcholine (Ach) is blocked by the venom. Ach and carbachol-induced responses are also inhibited in chick biventer-cervicis muscle while the contracture produced by is increased. The blockade of the miniature end-plate potenciais (m.e.p.ps.) induced by M. surinamensis venom in the rat diaphragm is antagonized by neostigmine and by 4 aminopyridine. M. surinamensis venom causes depolarization of the rat diaphragm muscle fibers. It induces contracture of the rat diaphragm and biventer cervicis, the contracture being more intense in the last muscle. It is also produced in curarized muscles and in muscles treated with tetrodotoxin. On the other hand, calcium excess (Krebbs solution with 10 mM CaCb) blocks the venom-induced contracture. These results show that M. surinamensis venom contains reversible curaremimetic toxin(s) and toxin(s) that induces desensitization of the end-plate nicotinic Receptor. They also show that it contains cardiotoxin-like toxin(s). Some results (increase of twitch tension before blockade, irreversibility of the neuromuscular blockade) suggest that Presynaptic Receptor toxins and irreversible curaremimetic toxins are contained in the M. surinamenis veno