The role of NMDA receptors in in vitro epileptogenesis

1992 ◽  
pp. 157-166 ◽  
Author(s):  
Wilkie A. Wilson ◽  
Steven Stasheff ◽  
Scott Swartzwelder ◽  
Suzanne Clark ◽  
William W. Anderson
Keyword(s):  
Nmda Receptors

Retinogeniculate EPSPs recorded intracellularly in the ferret lateral geniculate nucleus in vitro: Role of NMDA receptors

1992 ◽  
Vol 8 (6) ◽  
pp. 545-555 ◽  
Author(s):  
Manuel Esguerra ◽  
Young H. Kwon ◽  
Mriganka Sur
Keyword(s):  
Membrane Potential ◽  
Nmda Receptor ◽  
Nmda Receptors ◽  
Lateral Geniculate Nucleus ◽  
Excitatory Amino Acid ◽  
Optic Tract ◽  
Receptor Activation ◽  
Lateral Geniculate

AbstractWe used an in vitro preparation of the ferret lateral geniculate nucleus (LGN) to examine the role of the NMDA class of excitatory amino acid (EAA) receptors in retinogeniculate transmission. Intracellular recordings revealed that blockade of NMDA receptors both shortened the time course and reduced the amplitude of fast and slow components of excitatory postsynaptic potentials (EPSPs) evoked by optic tract stimulation. The amplitude and width of the EPSPs mediated by NMDA receptors increased as membrane potential was depolarized towards spike threshold. Individual LGN cells were influenced to varying extents by blockade of NMDA receptors; NMDA and non-NMDA receptor blockade together attenuated severely the entire retinogeniculate EPSP. The dependence of all components of retinogeniculate EPSPs (and action potentials) on NMDA receptor activation supports the hypothesis that the NMDA receptor participates in fast (<10 ms) synaptic events underlying conventional retinogeniculate transmission. The voltage dependence of the NMDA receptor-gated conductance suggests strongly that the transmission of retinal information through the LGN is subject to modulation by extraretinal inputs that affect the membrane potential of LGN neurons.

scholarly journals NMDA Receptors in Astrocytes: In Search for Roles in Neurotransmission and Astrocytic Homeostasis

2019 ◽  
Vol 20 (2) ◽  
pp. 309 ◽  
Author(s):  
Katarzyna Skowrońska ◽  
Marta Obara-Michlewska ◽  
Magdalena Zielińska ◽  
Jan Albrecht
Keyword(s):  
Nmda Receptors ◽  
Brain Slices ◽  
Cultured Astrocytes ◽  
Specific Proteins ◽  
Homeostatic Function ◽  
Inward Rectifying Potassium Channel ◽  
And Function

Studies of the last two decades have demonstrated the presence in astrocytic cell membranes of N-methyl-d-aspartate (NMDA) receptors (NMDARs), albeit their apparently low abundance makes demonstration of their presence and function more difficult than of other glutamate (Glu) receptor classes residing in astrocytes. Activation of astrocytic NMDARs directly in brain slices and in acutely isolated or cultured astrocytes evokes intracellular calcium increase, by mutually unexclusive ionotropic and metabotropic mechanisms. However, other than one report on the contribution of astrocyte-located NMDARs to astrocyte-dependent modulation of presynaptic strength in the hippocampus, there is no sound evidence for the significant role of astrocytic NMDARs in astrocytic-neuronal interaction in neurotransmission, as yet. Durable exposure of astrocytic and neuronal co-cultures to NMDA has been reported to upregulate astrocytic synthesis of glutathione, and in this way to increase the antioxidative capacity of neurons. On the other hand, overexposure to NMDA decreases, by an as yet unknown mechanism, the ability of cultured astrocytes to express glutamine synthetase (GS), aquaporin-4 (AQP4), and the inward rectifying potassium channel Kir4.1, the three astroglia-specific proteins critical for homeostatic function of astrocytes. The beneficial or detrimental effects of astrocytic NMDAR stimulation revealed in the in vitro studies remain to be proven in the in vivo setting.

Role of NMDA receptors and voltage-activated calcium channels in an in vitro model of cerebral ischemia

1993 ◽  
Vol 612 (1-2) ◽  
pp. 278-288 ◽  
Author(s):  
Thomas Kral ◽  
Heiko J. Luhmann ◽  
Thomas Mittmann ◽  
Uwe Heinemann
Keyword(s):  
Cerebral Ischemia ◽  
Calcium Channels ◽  
Nmda Receptors ◽  
In Vitro Model ◽  
Vitro Model

scholarly journals NMDA Receptor Subtypes at Autaptic Synapses of Cerebellar Granule Neurons

2006 ◽  
Vol 96 (5) ◽  
pp. 2282-2294 ◽  
Author(s):  
Congyi Lu ◽  
Zhanyan Fu ◽  
Irina Karavanov ◽  
Robert P. Yasuda ◽  
Barry B. Wolfe ◽  
...  
Keyword(s):  
Nmda Receptors ◽  
Peak Amplitude ◽  
Cerebellar Granule Neurons ◽  
Receptor Subtypes ◽  
Granule Neurons ◽  
Cerebellar Granule ◽  
Quantal Size ◽  
Nr2a Subunit

We studied the action potential–evoked autaptic N-methyl-d-aspartate receptor-mediated excitatory postsynaptic currents (NMDA-EPSCs) using solitary cerebellar neurons cultured in microislands from wild-type (+/+), NR2A subunit knockout (NR2A−/−), and NR2C subunit knockout (NR2C−/−) mice. The peak amplitude of autaptic NMDA-EPSCs increased for all genotypes between days in vitro 8 (DIV8) and DIV13. Compared with +/+ cells at DIV13, NR2A−/− cells had smaller and NR2C−/− cells had larger NMDA-EPSCs. The decay time of these currents were all unexpectedly fast, except in NR2A−/− neurons, and showed small but significant shortening with development. Comparison of quantal parameters during development indicated an increase in quantal content in all genotypes. The synaptic portion of NMDA receptors measured using MK-801 blockade was roughly 50% in all genotypes at DIV8, and this percentage became slightly larger in NR2A−/− and NR2C−/− neurons at DIV12. The NR2B-selective antagonists Conantokin G and CP101,606 differed in their blocking actions with development, suggesting the presence of both heterodimeric NR1/NR2B and heterotrimeric NR1/NR2A/NR2B receptors. The most striking result we obtained was the significant increase of NMDA-EPSC peak amplitude and charge transfer in NR2C−/− mice. This was mainly the result of an increase in quantal size as estimated from miniature NMDA-EPSCs. The expression of NR2C subunit containing receptors was supported by the decreased Mg2+ sensitivity of NMDA receptors at DIV13 in +/+ but not in NR2C−/− cells. Thus solitary cerebellar granule neurons provide a novel model to investigate the role of receptor subtypes in the developmental changes of synaptic NMDA receptors.

Role of peripheral NMDA receptors in colorectal distension mediated afferent nerve activity: An In vitro study

2001 ◽  
Vol 120 (5) ◽  
pp. A329
Author(s):  
Jen Yu Wei ◽  
Yu Hua Wang ◽  
Emeran A. Mayer ◽  
James A. McRoberts
Keyword(s):  
Nmda Receptors ◽  
In Vitro Study ◽  
Afferent Nerve ◽  
Vitro Study ◽  
Nerve Activity ◽  
Colorectal Distension

The role of silicon in forages: A quantitative X-Ray study

1987 ◽  
Vol 45 ◽  
pp. 416-417
Author(s):  
Janet H. Woodward ◽  
D. E. Akin
Keyword(s):  
Sodium Acetate ◽  
Dry Matter ◽  
Acetate Buffer ◽  
Plant Tissues ◽  
Sodium Acetate Buffer ◽  
X Ray ◽  
Dry Matter Digestibility ◽  
Percent Composition

Silicon (Si) is distributed throughout plant tissues, but its role in forages has not been clarified. Although Si has been suggested as an antiquality factor which limits the digestibility of structural carbohydrates, other research indicates that its presence in plants does not affect digestibility. We employed x-ray microanalysis to evaluate Si as an antiquality factor at specific sites of two cultivars of bermuda grass (Cynodon dactvlon (L.) Pers.). “Coastal” and “Tifton-78” were chosen for this study because previous work in our lab has shown that, although these two grasses are similar ultrastructurally, they differ in in vitro dry matter digestibility and in percent composition of Si.Two millimeter leaf sections of Tifton-7 8 (Tift-7 8) and Coastal (CBG) were incubated for 72 hr in 2.5% (w/v) cellulase in 0.05 M sodium acetate buffer, pH 5.0. For controls, sections were incubated in the sodium acetate buffer or were not treated.

An integrated screening method for evaluating the pulmonary toxicity of inhaled particulates: Role of microscopic techniques in assessing pulmonary macrophage clearance functions

1990 ◽  
Vol 48 (3) ◽  
pp. 826-827
Author(s):  
David B. Warheit ◽  
Lena Achinko ◽  
Mark A. Hartsky
Keyword(s):  
Bronchoalveolar Lavage ◽  
Pulmonary Toxicity ◽  
Screening Method ◽  
Pulmonary Response ◽  
Inhaled Particles ◽  
Cytochemical Analysis ◽  
Pulmonary Macrophages ◽  
Integrated Screening

There is a great need for the development of a rapid and reliable bioassay to evaluate the pulmonary toxicity of inhaled particles. A number of methods have been proposed, including lung clearance studies, bronchoalveolar lavage analysis, and in vitro cytotoxicity tests. These methods are often limited in scope inasmuch as they measure only one dimension of the pulmonary response to inhaled, instilled or incubated dusts. Accordingly, a comprehensive approach to lung toxicity studies has been developed.To validate the method, rats were exposed for 6 hours or 3 days to various concentrations of either aerosolized alpha quartz silica (Si) or carbonyl iron (CI) particles. Cells and fluids from groups of sham and dust-exposed animals were recovered by bronchoalveolar lavage (BAL). Alkaline phosphatase, LDH and protein values were measured in BAL fluids at several time points postexposure. Cells were counted and evaluated for viability, as well as differential and cytochemical analysis. In addition, pulmonary macrophages (PM) were cultured and studied for morphology, chemotaxis, and phagocytosis by scanning electron microscopy.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

Anti-obesity role of Aster glehni extract: in vivo and in vitro effects

Planta Medica ◽  
2012 ◽  
Vol 78 (11) ◽  
Author(s):  
HM Lee ◽  
TG Ahn ◽  
CW Kim ◽  
HJ An
Keyword(s):  
In Vitro Effects
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