Search Results
Results 251 - 300 of 1845
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Vamos Eniko - - 2009
The metabolism of tryptophan mostly proceeds through the kynurenine pathway. The biochemical reaction includes both an agonist (quinolinic acid) at the N-methyl-d-aspartate receptor and an antagonist (kynurenic acid). Besides the N-methyl-d-aspartate antagonism, an important feature of kynurenic acid is the blockade of the alpha7-nicotinic acetylcholine receptor and its influence on ...
Smith Andrew J - - 2009
The essential amino acid tryptophan is primarily metabolised through the kynurenine pathway, some components of which may be neurotoxic. We have now examined the potential toxicity of several kynurenine metabolites in relation to the generation of oxidative stress and activation of cell death signalling pathways in cultured cerebellar granule neurons. ...
Champeil Elise - - 2009
The optimum geometries and binding energies of the complexes formed by AMPA and Kainic acid, as well as their anions with tyrosine, proline and some tripeptides are investigated with quantum chemical calculations (HF/6-31G**). It was found that receptors featuring the Tyr-Ala-Pro sequence exhibit stronger binding energies to the substrates than ...
Jiang Wei - - 2009
Ketamine, a non-competitive N-methyl-D-aspartate (NMDA) antagonist, is a commonly used injectable anaesthetic agent. In the present study, ketamine- and isoflurane-induced anaesthesias were tested to identify the influence of different anaesthesia methods in conjunction with the unilateral quinolinic acid-induced excitotoxic lesion rat model of Huntington's disease (HD). Quinolinic acid, a glutamate ...
Swamy Mummedy - - 2009
Neuronal excitation, involving the excitatory glutamate receptors, is recognized as an important underlying mechanism in neurodegenerative disorders. To understand their role in excitotoxicity, the nitric oxide synthase (NOS), argininosuccinate synthetase (AS), argininosuccinate lyase (AL), glutamine synthetase (GS), and arginase activities, along with the concentration of nitrate/nitrite, thiobarbituric acid-reactive substances (TBARS), ...
Ji Chao - - 2009
Excitotoxicity is one of the most extensively studied processes of neuronal death and plays an important role in Alzheimer's disease. In the present study, the protective effects of Gossypium herbaceam extracts (GHE) on learning and memory impairment induced by excitatory neurotoxin ibotenic acid were examined in vivo using Morris water ...
Filosa Rosanna - - 2009
A novel series of bicyclo[1.1.1]pentane-based omega-acidic amino acids, including (2S)- and (2R)-3-(3'-carboxybicyclo[1.1.1]pentyl)alanines (8 and 9), (2S)- and (2R)-2-(3'-carboxymethylbicyclo[1.1.1]pentyl)glycines (10 and 11), and (2S)- and (2R)-3-(3'-phosphonomethylbicyclo[1.1.1]pentyl)glycines (12 and 13), were synthesized and evaluated as glutamate receptor ligands. Among them, (2R)-3-(3'-phosphonomethylbicyclo[1.1.1]pentyl)glycine (13) showed relatively high affinity and selectivity at the NMDA receptor. ...
Munday Rex - - 2008
Seafood in many parts of the world may become contaminated with high levels of domoic acid and domoic acid isomers, and such seafood has been shown to cause toxic effects in humans and in marine animals. Domoic acid itself has been held responsible for the observed effects, although the possible ...
Wang Ying Y Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, - - 2008
Mammalian neuronal DEG/ENaC channels known as ASICs (acid-sensing ion channels) mediate sensory perception and memory formation. ASICS are closed at rest and are gated by protons. Members of the DEG/ENaC family expressed in epithelial tissues are called ENaCs and mediate Na(+) transport across epithelia. ENaCs exhibit constitutive activity and strict ...
Oliveira Joao F - - 2008
Membrane currents of layer V pyramidal cells in slices of the rat prefrontal cortex (PFC) were recorded with the patch-clamp technique. In an Mg2+-free superfusion medium l-trans-pyrrolidine-2,4-dicarboxylic acid (PDC), a preferential blocker of astrocytic glutamate transporters, caused inward current due to the activation of NMDA receptors. The blockade of conducted ...
Tiedeken Jessica A - - 2009
California sea lions have a large body burden of organochlorine pesticides, and over the last decade they have also been subject to domoic acid poisoning. Domoic acid poisoning, previously recognized in adult animals, is now viewed as a major cause of prenatal mortality. The appearance of a chronic juvenile domoic ...
Mikati Mohamad A - - 2008
Status epilepticus (SE) induces a number of events leading to programmed cell death (PCD). The aim of our work is to study the time sequence of activation of different factors in experimental SE (intraperitoneal kainic acid (KA) model). We studied ceramide, a known mediator of apoptosis in multiple models, sphingomyelinases ...
Vranyac-Tramoundanas Alexandra - - 2008
Excitatory mediated neuronal injury has been shown to involve a complex cascade of events. However, the associated cardiac damage reported in humans and marine animals following exposure to excitotoxins has not been well characterized. We hypothesized that the excitotoxin domoic acid can traverse cardiac cell membranes and elicit a deleterious ...
Sagot Emanuelle - - 2008
( S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the central nervous system (CNS) activating the plethora of ionotropic Glu receptors (iGluRs) and metabotropic Glu receptors (mGluRs). In this paper, we present a chemo-enzymatic strategy for the enantioselective synthesis of five new Glu analogues 2a- f ( 2d is ...
Sagot Emanuelle - - 2008
In the mammalian central nervous system (CNS), the action of sodium dependent excitatory amino acid transporters (EAATs) is responsible for termination of glutamatergic neurotransmission by reuptake of ( S) -glutamate (Glu) from the synaptic cleft. Five EAAT subtypes have been identified, of which EAAT1-4 are present in the CNS, while ...
Fraser Mhoyra - - 2008
It is widely hypothesized that accumulation of excitatory amino acids, and oxygen free radicals during or after exposure to hypoxia-ischemia play a pivotal role in preterm periventricular white matter injury; however, there is limited evidence in the intact brain. In preterm fetal sheep (0.65 gestation; term 147 days) we found ...
Szyndler Janusz - - 2008
It is not well recognized how disturbances in the local metabolism of some amino acids, especially glutamate and GABA, may lead to seizures. In the presented study, we have examined changes in the hippocampal steady state concentrations of amino acids involved in pentylenetetrazole-kindled and freely moving rats. It was found ...
Knyihar-Csillik E - - 2008
Administration of nitroglycerol in a migraine model results in an increased number of c-fos-expressing secondary sensory neurons in the caudal trigeminal nucleus. Since synapses between first- and second-order trigeminal neurons are mediated by excitatory amino acids, NMDA receptors are inhibited by kynurenic acid, though this crosses the blood-brain barrier only ...
Glasser F - - 2008
In ruminants, dietary lipids are extensively hydrogenated by rumen micro-organisms, and the extent of this biohydrogenation is a major determinant of long-chain fatty acid profiles of animal products (milk, meat). This paper reports on the duodenal flows of C18 fatty acids and their absorption in the small intestine, using a ...
Rózsa Eva - - 2008
Kynurenic acid is an endogenous product of the tryptophan metabolism. Studies on the mechanism of its action have revealed that kynurenic acid at high concentrations is a competitive antagonist of the N-methyl-D-aspartate receptor and acts as a neuroprotectant in different neurological disorders. This in vitro investigation was designed to show ...
Amitani Misato - - 2008
PK11195, a selective PBR ligand, has been reported to exert a protective effect against the neuronal damage induced by the intrastriatal infusion of quinolinic acid, an excitatory amino acid. The neuroprotective effect of PK11195 observed at 48 h after the infusion was mediated by the inhibition of microglial activation. The ...
Pinto Andrea - - 2008
The two enantiomeric pairs of erythro- and threo-amino-(3'-hydroxy-4',5'-dihydro-isoxazol-5'-yl)-acetic acids were synthesized via the 1,3-dipolar cycloaddition of bromonitrile oxide to ( R)- or ( S)-3-( tert-butoxycarbonyl)-2,2-dimethyl-4-vinyloxazolidine. The pharmacological profiles of the studied amino acids reflect the relationship between the activity/selectivity and the stereochemistry of the two stereogenic centers: while the (2 ...
Nakamura Tomohiro - - 2008
We previously reported that a sulfur-containing neuroprotective substance named serofendic acid purified and isolated from fetal calf serum prevented glutamate neurotoxicity in rat cortical cultured neurons. In the present study, we investigated the effect of serofendic acid on ischemic injury induced by a transient occlusion of the middle cerebral artery ...
Schultz Irvin R - - 2008
Domoic acid (DA) is a neurotoxic amino acid produced by several marine algal species of the Pseudo-nitzschia (PN) genus. We studied the elimination of DA from hemolymph after intravascular (IV) injection in razor clams (Siliqua patula), mussels (Mytilus edulis) and Dungeness crabs (Cancer magister). Crabs were also injected with two ...
Kuc D - - 2008
Kynurenic acid is an antagonist of glutamate and alpha-7 nicotinic acetylcholine receptors and an agonist of the G: -protein-coupled receptor GPR35, which is predominantly expressed in immune and gastrointestinal tissues. In this study, we report that kynurenic acid is present in the lumen of rat small intestine in micromolar concentration ...
Taleb-Contini Silvia H - - 2008
Aiming at contributing with the search for neuroactive substances from natural sources, we report for the first time antinociceptive and anticonvulsant effects of some Lychnophora species. We verify the protective effects of polar extracts (600 mg/kg, intraperitoneally), and methanolic fractions of L. staavioides and L. rupestris (100 mg/kg, intraperitoneally) in ...
Velloso Nádia Aléssio - - 2008
Polyamines are aliphatic amines containing nucleophilic centers that are found in all eukaryotic cells, including brain cells. These compounds determine neuroprotection in experimental models of cerebral ischemia and neurotoxicity. In the current study we investigated the protective effects of spermine, an agonist of the polyamine binding site at the N-methyl-d-aspartate ...
Ban Ju Yeon - - 2008
Our previous studies reported that methanol extract of Sanguisorbae radix from Sanguisorba officinalis L. (Rosaceae) prevented neuronal cell damage induced by Abeta (25-35) in vitro. The present study was carried out to investigate the effect of gallic acid isolated from Sanguisorbae radix on Abeta (25-35)-induced neurotoxicity using cultured rat cortical ...
Chiou Wen-Hua - - 2008
Kainic acid, rigidified (S)-glutamic acid, is a well-known kainite receptor agonist for the excitatory transmission in the central nerve system. Our interest in highly selective kainite ligands, prompted us to design a series of new kainic homologues, "homokainoids", i.e., conformationally rigidified (S)-glutamic acids. For the syntheses of enantiopure novel homokainoids ...
Pulido Olga M - - 2008
Domoic acid was identified as the toxin responsible for an outbreak of human poisoning that occurred in Canada in 1987 following consumption of contaminated blue mussels [Mytilus edulis]. The poisoning was characterized by a constellation of clinical symptoms and signs. Among the most prominent features described was memory impairment which ...
Rozsa Eva - - 2008
The kynurenine pathway converts tryptophan into various compounds, including L-kynurenine, which in turn can be converted into the excitatory amino acid receptor antagonist kynurenic acid. The ionotropic glutamate receptors have been considered to be attractive targets for new anticonvulsants in neurological disorders such as epileptic seizure. This study was designed ...
Stephens Nicholas R - - 2008
Ionotropic glutamate (Glu) receptors in the central nervous system of animals are tetrameric ion channels that conduct cations across neuronal membranes upon binding Glu or another agonist. Plants possess homologous molecules encoded by GLR genes. Previous studies of Arabidopsis thaliana root cells showed that the amino acids alanine (Ala), asparagine ...
Youssef Farid F - - 2008
Lifelong calorie restriction is the only known intervention that has been shown to consistently increase life span and reduce the effects of aging on the brain. Given the difficulties of replicating lifelong calorie restriction within human populations, we have sought to assess the effects of short-term adult-onset calorie restriction upon ...
Luccini Elisa - - 2007
Presynaptic NMDA autoreceptors regulating glutamate release have rarely been investigated. High-micromolar N-methyl-D-aspartate (NMDA) was reported to elicit glutamate release from hippocampal synaptosomes in a Ca(2+)-independent manner by reversal of excitatory amino acid transporters. The aim of this work was to characterize excitatory amino acid release evoked by low-micromolar NMDA from ...
Beretta Giangiacomo - - 2007
KYNA, a Trp metabolite, shows neuroprotective activity against excitotoxic amino acids by antagonizing the NMDA receptor (glycine, glutamate). Here we report the identification of KYNA by a combination of ESI-MS/MS and 1D- and 2D-NMR analyses in honey varieties of arboreal origin. KYNA are absent in single-flower honeys from herbal flowers. ...
Conigrave A D - - 2007
The calcium-sensing receptor is a multimodal, multimetabolic sensor that mediates the feedback-dependent control of whole body calcium metabolism. Remarkably, in addition to its role in Ca(2+)(o) (extracellular Ca(2+)) sensing, the CaR (Ca(2+)-sensing receptor) also responds to L-amino acids. L-amino acids appear to activate, predominantly, a signalling pathway coupled with intracellular ...
Burns Justina M - - 2007
The environmental degradation of a mixture of domoic acid (DA) and kainic acid (KA) in seawater with and without added transition metals is reported. The association constants for kainic acid with Fe (III) and Cu (II) were determined using (1)H nuclear magnetic resonance (NMR; K1,Fe(III) = 2.27 x 10(12), K2,Fe(III) ...
Wéber Ildikó - - 2007
The circuits that generate rhythmic locomotor activities are located in the ventromedial area of the lumbar spinal cord and comprise commissural interneurons necessary for left-right alternation during walking movements. In this study we injected biotinylated dextran amine (BDA) into the ventromedial gray matter of the lumbar spinal cord of neonatal ...
Giordano Gennaro - - 2007
Exposure of mouse cerebellar granule neurons (CGNs) to domoic acid induced cell death, either by apoptosis or by necrosis, depending on its concentration. Necrotic damage predominated in response to domoic acid above 0.1 microM. In contrast, cell injury with apoptotic features (assessed by Hoechst staining and DNA laddering assay) was ...
Hosseinzadeh Zohreh Z Department of Biology, Shahid Chamran University, Ahwaz, - - 2007
The aim of the present study is for evaluating the effect of different doses of palmitic acid on spatial learning in T-maze. So, Wister adult male rats were used in five groups and considered 10 rats for each group. The first group as a control group was fed with ordinary ...
Maldonado Perla Deyanira - - 2007
Reactive oxygen and nitrogen species formation leads to DNA damage in animals treated with quinolinic acid. Poly(ADP-ribose) polymerase-1 (PARP-1) is a protein involved in the DNA base excision repair system. Its overactivation promotes cellular energy deficit and necrosis. Here, we evaluated the effect of PJ-34, a potent inhibitor of PARP-1, ...
Nikonov Alexander A - - 2007
Odorant specificity to l-alpha-amino acids was determined electrophysiologically for 93 single catfish olfactory receptor neurons (ORNs) selected for their narrow excitatory molecular response range (EMRR) to only one type of amino acid (i.e., Group I units). These units were excited by either a basic amino acid, a neutral amino acid ...
Mao Hui H Department of Radiology and Frederick Philips MR Research Center, Emory University School of Medicine, 1364 Clifton Road, Atlanta, Georgia 30322, USA, - - 2007
The solid-state high resolution magic angle spinning nuclear magnetic resonance (HRMAS NMR) technique was applied in this work to characterize and quantify the neurochemical changes in the rat hippocampus (CA1 or CA3) after local administration of kainic acid (KA). Intact tissue samples obtained from the KA treated and control brain ...
Erhardt Sophie - - 2007
In recent years progress in the field of schizophrenia research has led to the suggestion that dopamine only plays an intermediary role in the pathophysiology of the disease and that the main abnormalities lie elsewhere. In particular, deficits in brain glutamatergic systems are suggested to play a prominent role in ...
Vuong Leeza A Q - - 2008
While cannabinoid receptor agonists reduce the abnormal pain sensations associated with animal models of neuropathic pain states they also produce CB(1) receptor mediated side effects. Recently, a number of arachidonic acid-amino acid conjugates, including N-arachidonyl-glycine (NAGly), have been identified which are structurally related to the endocannabinoid arachidonyl ethanolamide (anandamide). In ...
Hartai Zsuzsanna - - 2007
Substantial evidence indicates that neuroactive kynurenine metabolites play a role in the normal physiology of the human brain, and are involved in the pathology of neurodegenerative disorders such as Parkinson's disease and Huntington's disease. A side-arm product of the pathway, kynurenic acid (KYNA), which is synthesized by the irreversible transamination ...
Tranberg Mattias - - 2007
Efflux and tissue content of N-acetylaspartate (NAA) and amino acids were evaluated from cultured and acutely prepared hippocampal slices in response to changes in osmolarity. The osmoregulator taurine, but not NAA, was lost from both types of slices after moderate reductions in extracellular osmolarity (-60 mOsm) for 10-48 h. Hypoosmotic ...
Shim Eon-Jeong - - 2007
In the present study, we examined nociceptive behaviors on various pain models after the pretreatment of kainic acid intracerebroventricularly. We found that intracerebroventricular administration of kainic acid shows significant neuronal damage on the hippocampal CA3 region in the brain slices stained with cresyl violet. Compared to the control group, intracerebroventricular ...
Luchowski Piotr - - 2007
The influence of nitric oxide (NO) donors, S-nitroso-N-acetylpenicillamine (SNAP), and 3-morpholinosydnonimine (SIN-1), on the central production of an endogenous glutamate receptor antagonist, kynurenic acid, was evaluated in vitro. In cortical slices, SNAP and SIN-1 potently increased the extracellular concentration of kynurenic acid. A free radical scavenger, l-ascorbate reversed this effect. ...
Nikonov Alexander A - - 2007
A paucity of information exists concerning the processing of odorant information by single neurons in any vertebrate above the level of the olfactory bulb (OB). In this report, odorant specificity to four types of L-alpha-amino acids (neutral with long side-chains, neutral with short side-chains, basic and acidic), known biologically relevant ...
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