Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Involvement of metabotropic glutamate receptors in taurine release in the adult and developing mouse hippocampus (1999)
    Springer
    Amino acids 16 (1999), S. 165-179 
    Details
    ISSN: 1438-2199
    Keywords: Amino acids ; Taurine release ; Metabotropic glutamate receptors ; Hippocampal slices ; Adult ; Developing mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The inhibitory amino acid taurine has been held to function as an osmoregulator and modulator of neural activity, being particularly important in the immature brain. lonotropic glutamate receptor agonists are known markedly to potentiate taurine release. The effects of different metabotropic glutamate receptor (mGluR) agonists and antagonists on the basal and K+-stimulated release of [3H]taurine from hippocampal slices from 3-month-old (adult) and 7-day-old mice were now investigated using a superfusion system. Of group I metabotropic glutamate receptor agonists, quisqualate potentiated basal taurine release in both age groups, more markedly in the immature hippocampus. This action was not antagonized by the specific antagonists of group I but by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 6-nitro-7-sulphamoylbenzo[f]quinoxaline-2,3-dione (NBQX), which would suggest an involvement of ionotropic glutamate receptors. (S)-3,5-dihydroxyphenylglycine (DHPG) potentiated the basal release by a receptor-mediated mechanism in the immature hippocampus. The group II agonist (2S, 2′R, 3′R)-2-(2′,3′-dicarboxycyclopropyl)glycine (DCG IV) markedly potentiated basal taurine release at both ages. These effects were antagonized by dizocilpine, indicating again the participation of ionotropic receptors. Group III agonists slightly potentiated basal taurine release, as did several antagonists of the three metabotropic receptor groups. Potassium-stimulated (50 mM K+) taurine release was generally significantly reduced by mGluR agents, mainly by group I and II compounds. This may be harmful to neurons in hyperexcitatory states. On the other hand, the potentiation by mGluRs of basal taurine release, particularly in the immature hippocampus, together with the earlier demonstrated pronounced enhancement by activation of ionotropic glutamate receptors, may protect neurons against excitotoxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01321534
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Mechanisms of D-Aspartate Release Under Ischemic Conditions in Mouse Hippocampal Slices (1999)
    Springer
    Neurochemical research 24 (1999), S. 1009-1016 
    Details
    ISSN: 1573-6903
    Keywords: D-aspartate release ; hippocampal slices ; ischemia ; cell-damaging conditions ; metabolic poisons ; mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The release of preloaded D-[3H]aspartate, an unmetabolizable analogue of L-glutamate, was studied in superfused hippocampal slices from 7-day-old and 3-month-old (adult) mice under various cell-damaging conditions, including hypoxia, hypoglycemia, ischemia, oxidative stress and the presence of free radicals and metabolic poisons. The release was generally markedly enhanced in most of the above conditions, the responses being greater in adults than in developing mice. The presence of dinitrophenol had the most pronounced effect at both ages, followed by NaCN- and free-radical-containing media and ischemia. Hypoxia did not affect release in the immature hippocampus. Under most conditions K+ stimulation (50 mM) was still able markedly to enhance D-aspartate release. This potentiation under cell-damaging conditions in both adult and developing hippocampus signifies that increased L-glutamate release contributes to excitotoxicity and subsequent cell death. The mechanisms of ischemia-induced release of D-aspartate were analyzed in the adult hippocampus using ion channel inhibitors and modified superfusion media. The induced release proved to be partly Ca2+-dependent and partly Ca2+-independent. The results obtained with Na+ omission and homo- and heteroexchange with D-aspartate and L-glutamate demonstrated that a part of the release in normoxia and ischemia is mediated by the reversal of Na+-dependent glutamate transporters. The Na+ channel blockers amiloride and riluzole reduced the ischemia-induced release, also indicating the involvement of Na+ channels. In addition to this, the enhanced release of D-aspartate may comprise a swelling-induced component through chloride channels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021052725921
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Glutamate agonists and [3H]GABA release from rat hippocampal slices: Involvement of metabotropic glutamate receptors in the quisqualate-evoked release (1994)
    Springer
    Neurochemical research 19 (1994), S. 729-734 
    Details
    ISSN: 1573-6903
    Keywords: GABA release ; quisqualate ; glutamate receptors ; metabotropic receptors ; hippocampal slices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of glutamate agonists and their selective antagonists on the Ca2+-dependent and independent releases of [3H]GABA from rat coronal hippocampal slices were studied in a superfusion system. The Ca2+-dependent release evoked by glutamate, kainate and N-methyl-D-aspartate (NMDA) gradually declined with time despite the continuous presence of the agonists. Quisqualate (QA) caused a sustained release which exhibited no tendency to decline within the 20-min period of stimulation. This release was enhanced in Ca2+-free medium. The release evoked by QA in Ca2+-containing medium was significantly inhibited by (+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohept-5,10-imine hydrogen maleate (MK-801) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), showing that QA activates NMDA receptors directly or indirectly through (RS)-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors. The inhibition of MK-801 was slightly diminished and that of CNQX totally abolished in Ca2+-free medium. Verapamil inhibited the QA-activated release in both Ca2+-containing and Ca2+-free media. The effect of QA but not that of AMPA was blocked in Ca2+-free medium by L(+)-2-amino-3-phosphonopropionate (L-AP3), a selective antagonist of the metabotropic glutamate receptor. It is suggested that the sustained release of GABA is also mediated partly by activation of metabotropic receptors and mobilization of Ca2+ from intracellular stores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00967713
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Interference of S-Alkyl Derivatives of Glutathione with Brain Ionotropic Glutamate Receptors (1998)
    Springer
    Neurochemical research 23 (1998), S. 1085-1091 
    Details
    ISSN: 1573-6903
    Keywords: Glutamate receptors ; glutathione derivatives ; ligand binding ; Ca2+ influx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of glutathione, glutathione sulfonate and S-alkyl derivatives of glutathione on the binding of glutamate and selective ligands of ionotropic N-methyl-D-aspartate (NMDA) and non-NMDA receptors were studied with mouse synaptic membranes. The effects of glutathione and its analogues on 45Ca2+ influx were also estimated in cultured rat cerebellar granule cells. Reduced and oxidized glutathione, glutathione sulfonate, S-methyl-, -ethyl-, -propyl-, -butyl- and -pentylglutathione inhibited the Na+-independent binding of L-[3H]glutamate. They strongly inhibited also the binding of (S)-2-amino-3-hydroxy-5-[3H]methyl-4-isoxazolepropionate [3H]AMPA (IC50 values: 0.8–15.9 μM). S-Alkylation of glutathione rendered the derivatives unable to inhibit [3H]kainate binding. The NMDA-sensitive binding of L-[3H]glutamate and the binding of 3-[(R)-2-carboxypiperazin-4-yl][1,2-3H]propyl-1-phosphonate ([3H]CPP, a competitive antagonist at NMDA sites) were inhibited by the peptides at micromolar concentrations. The strychnine-insensitive binding of the NMDA coagonist [3H]glycine was attenuated only by oxidized glutathione and glutathione sulfonate. All peptides slightly enhanced the use-dependent binding of [3H]dizocilpine (MK-801) to the NMDA-gated ionophores. This effect was additive with the effect of glycine but not with that of saturating concentrations of glutamate or glutamate plus glycine. The glutamate- and NMDA-evoked influx of 45Ca2+ into cerebellar granule cells was inhibited by the S-alkyl derivatives of glutathione. We conclude that besides glutathione the endogenous S-methylglutathione and glutathione sulfonate and the synthetic S-alkyl derivatives of glutathione act as ligands of the AMPA and NMDA receptors. In the NMDA receptor-ionophore these glutathione analogues bind preferably to the glutamate recognition site via their γ-glutamyl moieties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020712203611
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    β-Alanine Release from the Adult and Developing Hippocampus Is Enhanced by Ionotropic Glutamate Receptor Agonists and Cell-Damaging Conditions (1999)
    Springer
    Neurochemical research 24 (1999), S. 407-414 
    Details
    ISSN: 1573-6903
    Keywords: β-Alanine release ; hippocampal slices ; glutamate agonists ; cell-damaging conditions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The release of the inhibitory amino acid β-alanine was investigated in hippocampal slices from adult (3-month-old) and developing (7-day-old) mice, using a superfusion system. The release was enhanced by β-alanine itself and the structural analogs taurine and γ-aminobutyrate. It was dependent on Na+, but independent of Ca2+ in both mature and immature hippocampus, being thus mostly mediated by uptake carriers operating in an outward direction. The release was potentiated in the developing mice, but not affected in the adults, by the ionotropic glutamate receptor agonists N-methyl-D-aspartate, kainate, 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate and tetrazolylglycine in a receptor-mediated manner. Cell-damaging conditions, including hypoxia, hypoglycemia, ischemia, oxidative stress and the presence of free radicals, greatly enhanced β-alanine release at both ages, but more markedly in the adults. The great amounts of β-alanine, together with the inhibitory amino acids taurine and γ-aminobutyrate, released simultaneously with the excitatory amino acids in the hippocampus may constitute an important protective mechanism against excitotoxicity, which leads to neuronal death.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020941818168
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Lamotrigine and Carbamazepine Affect Differently the Release of D-[3H]Aspartate from Mouse Cerebral Cortex Slices: Involvement of NO (1999)
    Springer
    Neurochemical research 24 (1999), S. 1153-1159 
    Details
    ISSN: 1573-6903
    Keywords: Lamotrigine ; carbamazepine ; D-aspartate release ; veratridine ; potassium stimulation ; nitric oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of lamotrigine and carbamazepine on the release of preloaded D-[3H]aspartate and the involvement of nitric oxide were studied with mouse cerebral cortical slices in a superfusion system. Lamotrigine inhibited the veratridine-evoked release, whereas the K+-stimulated release was attenuated more strongly by carbamazepine than by lamotrigine. These effects were accentuated by the N-methyl-D-aspartate receptor antagonist L-2-amino-5-phosphonovalerate and the nitric oxide synthase inhibitor L-nitroarginine, but diminished by the nitric oxide donor sodium nitroprusside. The results show that in addition to the blockade of voltage-sensitive Na+ (and Ca2+) channels, NO-mediated mechanisms are probably involved in the anticonvulsant actions of carbamazepine and, in particular, those of lamotrigine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020716621300
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Enhanced GABA release in cerebral cortical slices derived from rats with thioacetamide-induced hepatic encephalopathy (1992)
    Springer
    Neurochemical research 17 (1992), S. 1187-1190 
    Details
    ISSN: 1573-6903
    Keywords: Hepatic encephalopathy ; thioacetamide ; cerebral cortex ; GABA release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The release of newly loaded [3H]GABA was studied in slices of different brain regions derived from rats in which acute hepatic encephalopathy (HE) was induced with a hepatotoxin thioacetamide. HE increased both spontaneous and high (50 mM) ammonium chloride-evoked GABA release in cerebral cortical slices by 38% and 50%, respectively. No effects of HE were noted in cerebellar or striatal slices. An increased release of GABA in the cerebral cortex may contribute to the endogenous benzodiazepine-mediated enhancement of GABAergic tone, which is thought to be partly responsible for the pathophysiological mechanism of HE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00968397
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Taurine in the developing cat: Uptake and release in different brain areas (1994)
    Springer
    Neurochemical research 19 (1994), S. 77-82 
    Details
    ISSN: 1573-6903
    Keywords: Taurine ; uptake ; release ; cat brain slices ; synaptosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Taurine is an important modulator of neuronal activity in the immature brain. In kittens, taurine deficiency causes serious dysfunction in the cerebellar and cerebral visual cortex. The processes of taurine transport in vitro were now studied for the first time in different brain areas in developing and adult cats. The uptake of taurine consisted initially of two saturable components, high- and low-affinity, in synaptosomal preparations from the developing cerebral cortex and cerebellum, but the high-affinity uptake component completely disappeared during maturation. The release of both endogenous and preloaded labeled taurine from brain slices measured in a superfusion system was severalfold stimulated with a slow onset by depolarizing K+ (50 mM) concentrations. K+ stimulation released markedly more taurine from the cerebral cortex, cerebellum and brain stem in kittens than in adult cats. The responses were largest in the cerebellum. Both uptake and release of taurine are thus highly efficient in the brain of kittens and may be of significance in view of the vulnerability of cats to taurine deficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00966732
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Release of [3H]Dopamine from Striatal and Cerebral Cortical Slices from Rats with Thioacetamide-Induced Hepatic Encephalopathy: Different Responses to Stimulation by Potassium Ions and Agonists of Ionotropic Glutamate Receptors (1997)
    Springer
    Neurochemical research 22 (1997), S. 101-106 
    Details
    ISSN: 1573-6903
    Keywords: Hepatic encephalopathy ; brain slices ; striatum ; frontal cortex ; glutamate receptors ; dopamine release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of depolarizing stimuli; high (50 mM) potassium ions and the glutamate receptor agonists N-methyl-D-aspartate, kainate and 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) on the release of newly-loaded [3H]dopamine were studied in frontal cortical and striatal slices from control rats and from rats with acute hepatic encephalopathy induced with a hepatotoxin, thioacetamide. Hepatic encephalopathy enhanced the stimulatory effect of potassium ions by 20% in striatal slices and by 34% in frontal cortical slices. In striatal slices the stimulatory effects of N-methyl-D-aspartate and kainate were depressed in hepatic encephalopathy by 46% and 21%, respectively, which may be taken to reflect impaired modulation of striatal dopamine release by glutamate acting at N-methyl-D-aspartate or kainate receptors. In frontal cortical slices, the stimulatory effect of kainate was enhanced by 35% in hepatic encephalopathy but N-methyl-D-aspartate-stimulated release was not affected. The release evoked by 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate was not affected in hepatic encephalopathy in either brain region. Stimulation of dopamine release in the frontal cortex by depolarization or glutamate acting at kainate receptors could inhibit the activity of descending corticostriatal glutamatergic pathways, further impairing regulation of dopamine release by glutamate in the stratum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1027347019707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Pharmacological characterization of glutamate binding sites in cultured cerebellar granule cells and cortical astrocytes (1994)
    Springer
    Neurochemical research 19 (1994), S. 111-115 
    Details
    ISSN: 1573-6903
    Keywords: Cerebellar granule cells ; cortical astrocytes ; excitatory amino acid ; binding ; glutamate receptor subtypes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Membranes prepared from cerebellar granule cells and cortical astrocytes exhibited specific, saturable binding ofl-[3H]glutamate. The apparent binding constant K d was 135 nM and 393 nM and the maximal binding capacity Bmax 42 and 34 μmol/kg in granule cells and astrocytes, respectively. In granule cells the binding was strongly inhibited by the glutamate receptor agonists kainate, quisqualate, N-methyl-d-aspartate (NMDA),l-homocysteate and ibotenate, and the antagonistdl-5-aminophosphonovalerate. In astrocytes, only quisqualate among these was effective.l-Aspartate,l-cysteate,l-cysteinesulphinate and γ-d-glutamylglycine were inhibitors in both cell types. The binding was totally displaced in both cell types byl-cysteinesulphinate with IC50 in the micromolar range. In astrocytes the binding was also totally displaced by quisqualate, but in granule cells only partially by NMDA, kainate and quisqualate in turn. It is concluded from the relative potencies of agonists and antagonists in [3H]glutamate binding that cerebellar granule cells express the NMDA, kainate and quisqualate types of the glutamate receptor, while only the quisqualate-sensitive binding seems to be present in cortical astrocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00966803
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...