Search results for "nmda receptor"

Structural Mechanism of N-Methyl-D-Aspartate Receptor Type 1 Partial Agonism

2012

N-methyl-D-aspartate (NMDA) receptors belong to a family of ionotropic glutamate receptors that contribute to the signal transmission in the central nervous system. NMDA receptors are heterotetramers that usually consist of two GluN1 and GluN2 monomers. The extracellular ligand-binding domain (LBD) of a monomer is comprised of discontinuous segments that form the functional domains D1 and D2. While the binding of a full agonist glycine to LBD of GluN1 is linked to cleft closure and subsequent ion-channel opening, partial agonists are known to activate the receptor only sub-maximally. Although the crystal structures of the LBD of related GluA2 receptor explain the mechanism for the partial a…

Exposure to gp120 of HIV-1 induces an increased release of arachidonic acid in rat primary neuronal cell culture followed by NMDA receptor-mediated n…

1995

After incubation of highly enriched neurons from rat cerebral cortex with the HIV-1 coat protein gp120 for 18 h, cells showed fragmentation of DNA at internucleosomal linkers followed by NMDA receptor-mediated neurotoxicity. We report that in response to exposure to gp120 cells react with an increased release of arachidonic acid (AA) via activation of phospholipase A2. This process was not inhibited by NMDA receptor antagonists. To investigate the role of AA on the sensitivity of the NMDA receptor towards its agonist, low concentrations of NMDA were co-administered with AA. This condition enhanced the NMDA-mediated cytotoxicity. Administration of mepacrine reduced cytotoxicity caused by gp1…

No association of alcohol dependence with a NMDA-receptor 2B gene variant

2003

Excitotoxic Hippocampal Membrane Breakdown and its Inhibition by Bilobalide: Role of Chloride Fluxes

2003

We have previously shown that hypoxia and N-methyl-D-aspartate (NMDA) receptor activation induce breakdown of choline-containing phospholipids in rat hippocampus, a process which is mediated by calcium influx and phospholipase A (2) activation. Bilobalide, a constituent of Ginkgo biloba, inhibited this process in a potent manner (Weichel et al., Naunyn-Schmiedeberg's Arch. Pharmacol. 360, 609-615, 1999). In this study, we used fluorescence microscopy and radioactive flux measurements to show that bilobalide does not interfere with NMDA-induced calcium influx. Instead, bilobalide seems to inhibit NMDA-induced fluxes of chloride ions through ligand-operated chloride channels. In our experimen…

The endocannabinoid N-arachidonoyldopamine (NADA) exerts neuroprotective effects after excitotoxic neuronal damage via cannabinoid receptor 1 (CB(1)).

2012

Endocannabinoids exert numerous effects in the CNS under physiological and pathological conditions. The aim of the present study was to examine whether the endocannabinoid N-arachidonoyldopamine (NADA) may protect neurons in excitotoxically lesioned organotypic hippocampal slice cultures (OHSC). OHSC were excitotoxically lesioned by application of N-methyl-d-aspartate (NMDA, 50 μM) for 4 h and subsequently treated with different NADA concentrations (0.1 pM-50 μM) alone or in combination with cannabinoid receptor antagonists. NADA protected dentate gyrus granule cells and caused a slight reduction in the number of microglial cells. The number of degenerated neurons significantly decreased be…

Carbachol-induced network oscillations in the intact cerebral cortex of the newborn rat.

2003

In mature cortex, activation of the cholinergic system induces oscillatory network activity and facilitates synaptic plasticity. We used an in vitro preparation of the intact cerebral cortex and cortical slices of the neonatal rat to study carbachol (CCh, >or=30 micro M)-induced network oscillations during the early postnatal period. Multi-site extracellular recordings revealed CCh-induced transient beta oscillations with an average duration of 4.6 +/- 0.2 s, amplitude of 123 +/- 7.4 microV and frequency of 17.7 +/- 0.5 Hz. These oscillations propagated uniformly at 0.5-1.5 mm/s over the cortex and were reversibly blocked by tetrodotoxin (TTX) and atropine, indicating that they depended on …

Activity-Dependent Regulation of Neuronal Apoptosis in Neonatal Mouse Cerebral Cortex

2007

A massive neuronal loss during early postnatal development has been well documented in the murine cerebral cortex, but the factors that drive cells into apoptosis are largely unknown. The role of neuronal activity in developmental apoptosis was studied in organotypic neocortical slice cultures of newborn mice. Multielectrode array and whole-cell patch-clamp recordings revealed spontaneous network activity characterized by synchronized burst discharges, which could be blocked by tetrodotoxin and ionotropic glutamate receptor antagonists. The identical neuropharmacological manipulations also caused a significant increase in the number of apoptotic neurons as early as 6 h after the start of dr…

Control of cortical neuronal migration by glutamate and GABA

2015

Neuronal migration in the cortex is controlled by the paracrine action of the classical neurotransmitters glutamate and GABA. Glutamate controls radial migration of pyramidal neurons by acting primarily on NMDA receptors and regulates tangential migration of inhibitory interneurons by activating non-NMDA and NMDA receptors. GABA, acting on ionotropic GABAA-rho and GABAA receptors, has a dichotomic action on radially migrating neurons by acting as a GO signal in lower layers and as a STOP signal in upper cortical plate (CP), respectively. Metabotropic GABAB receptors promote radial migration into the CP and tangential migration of interneurons. Besides GABA, the endogenous GABAergic agonist …

Blocking NMDA-receptors in the pigeon's "prefrontal" caudal nidopallium impairs appetitive extinction learning in a sign-tracking paradigm

2015

Extinction learning provides the ability to flexibly adapt to new contingencies by learning to inhibit previously acquired associations in a context-dependent manner. The neural networks underlying extinction learning were mostly studied in rodents using fear extinction paradigms. To uncover invariant properties of the neural basis of extinction learning, we employ pigeons as a model system. Since the prefrontal cortex of mammals is a key structure for extinction learning, we assessed the role of N-methyl-D-aspartate receptors (NMDARs) in the nidopallium caudolaterale, the avian functional equivalent of mammalian prefrontal cortex. Since NMDARs in prefrontal cortex have been shown to be rel…

A modeling study suggesting how a reduction in the context-dependent input on CA1 pyramidal neurons could generate schizophrenic behavior.

2011

The neural mechanisms underlying schizophrenic behavior are unknown and very difficult to investigate experimentally, although a few experimental and modeling studies suggested possible causes for some of the typical psychotic symptoms related to this disease. The brain region most involved in these processes seems to be the hippocampus, because of its critical role in establishing memories for objects or events in the context in which they occur. In particular, a hypofunction of the N-methyl-D-aspartate (NMDA) component of the synaptic input on the distal dendrites of CA1 pyramidal neurons has been suggested to play an important role for the emergence of schizophrenic behavior. Modeling st…