Linked Life Data

11422455

Source:http://linkedlifedata.com/resource/pubmed/id/11422455

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
2001-6-25
pubmed:abstractText
Kynurenic acid is a tryptophan metabolite provided with antagonist activity on ionotropic glutamate and alpha7 nicotinic acetylcholine receptors. We noticed that in rats with a dialysis probe placed in the head of their caudate nuclei, local administration of kynurenic acid (30-100 nM) significantly reduced glutamate output. Qualitatively and quantitatively similar effects were observed after systemic administration of kynurenine hydroxylase inhibitors, a procedure able to increase brain kynurenate concentrations. Interestingly, in microdialysis studies, methyllycaconitine (0.3-10 nM), a selective alpha7 nicotinic receptor antagonist, also reduced glutamate output. In isolated superfused striatal synaptosomes, kynurenic acid (100 nM), but not methyllycaconitine, inhibited the depolarization (KCl 12.5 mM)-induced release of transmitter or previously taken-up [3H]-D-aspartate. This inhibition was not modified by glycine, N-methyl-D-aspartate or subtype-selective kainate receptor agents, while CNQX or DNQX (10 microM), two AMPA and kainate receptor antagonists, reduced kynurenic acid effects. Low concentrations of kynurenic acid, however, did not modify [3H]-kainate (high and low affinity) or [3H]-AMPA binding to rat brain membranes. Finally, because metabotropic glutamate (mGlu) receptors modulate transmitter release in striatal preparations, we evaluated, with negative results, kynurenic acid (1-100 nM) effects in cells transfected with mGlu1, mGlu2, mGlu4 or mGlu5 receptors. In conclusion, our data show that kynurenate-induced inhibition of glutamate release is not mediated by glutamate receptors. Nicotinic acetylcholine receptors, however, may contribute to the inhibitory effects of kynurenate found in microdialysis studies, but not in those found in isolated synaptosomes.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0953-816X
pubmed:author
pubmed:issnType
Print
pubmed:volume
13
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2141-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:11422455-Animals, pubmed-meshheading:11422455-Brain, pubmed-meshheading:11422455-Caudate Nucleus, pubmed-meshheading:11422455-Excitatory Amino Acid Agonists, pubmed-meshheading:11422455-Excitatory Amino Acid Antagonists, pubmed-meshheading:11422455-Extracellular Space, pubmed-meshheading:11422455-Glutamic Acid, pubmed-meshheading:11422455-Kynurenic Acid, pubmed-meshheading:11422455-Male, pubmed-meshheading:11422455-Microdialysis, pubmed-meshheading:11422455-Presynaptic Terminals, pubmed-meshheading:11422455-Rats, pubmed-meshheading:11422455-Rats, Wistar, pubmed-meshheading:11422455-Receptors, Glutamate, pubmed-meshheading:11422455-Receptors, Nicotinic, pubmed-meshheading:11422455-Synaptic Transmission, pubmed-meshheading:11422455-Synaptosomes, pubmed-meshheading:11422455-Tritium
pubmed:year
2001
pubmed:articleTitle
Presynaptic kynurenate-sensitive receptors inhibit glutamate release.
pubmed:affiliation
Department of Preclinical and Clinical Pharmacology, Viale Pieraccini 6, University of Florence, 50139 Florence, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't