Calcium-dependent inactivation of synaptic NMDA receptors in hippocampal neurons

1. We examined whether synaptically activated N-methyl-D-aspartate (NMDA) receptors are regulated by intracellular calcium in cultured hippocampal neurons by comparing excitatory postsynaptic currents (EPSCs) to the previously described calcium-dependent regulation of whole cell NMDA currents. Standard whole cell recording and fast application methods were used. 2. Low-frequency (0.2 Hz) stimulation of EPSCs in the presence of 2-amino-5-phosphonovalerate (AP5) evoked a constant amplitude alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated EPSC. On removal of AP5 in Ca(2+)-containing solutions, the amplitude of the slow NMDA receptor-mediated EPSC decreased by approximately 50% during the next 10 stimuli. The decrease in the EPSC was dependent on the extracellular calcium concentration and stimulus frequency, consistent with Ca(2+)-dependent desensitization/inactivation of postsynaptic NMDA receptors. A whole cell prepulse of NMDA (10 microM, 10 s) in Ca(2+)-containing solutions inhibited the slow EPSC to a similar degree. A series of slow EPSCs also produced Ca(2+)-dependent inactivation of whole cell NMDA currents evoked in low calcium solutions. 3. These results demonstrate that synaptic NMDA receptors are inactivated by intracellular calcium and that calcium entry through synaptically activated NMDA receptors is sufficient to provide feedback inhibition of the slow EPSC.

Download Full-text

Induction of long-term potentiation without participation of N-methyl-D-aspartate receptors in kitten visual cortex

Journal of Neurophysiology ◽

10.1152/jn.1991.65.1.20 ◽

1991 ◽

Vol 65 (1) ◽

pp. 20-32 ◽

Cited By ~ 47

Author(s):

Y. Komatsu ◽

S. Nakajima ◽

K. Toyama

Keyword(s):

Nmda Receptors ◽

Stimulus Frequency ◽

Low Frequency ◽

Nmda Antagonist ◽

Long Term Potentiation ◽

Conditioning Stimulation ◽

Postsynaptic Potential ◽

Term Potentiation ◽

Stimulation Of

1. Intracellular recording was made from layer II-III cells in slice preparations of kitten (30-40 days old) visual cortex. Low-frequency (0.1 Hz) stimulation of white matter (WM) usually evoked an excitatory postsynaptic potential (EPSP) followed by an inhibitory postsynaptic potential (IPSP). The postsynaptic potentials (PSPs) showed strong dependence on stimulus frequency. Early component of EPSP and IPSP evoked by weak stimulation both decreased monotonically at frequencies greater than 0.5-1 Hz. Strong stimulation similarly depressed the early EPSP at higher frequencies (greater than 2 Hz) and replaced the IPSP with a late EPSP, which had a maximum amplitude in the stimulus frequency range of 2-5 Hz. 2. Very weak WM stimulation sometimes evoked EPSPs in isolation from IPSPs. The falling phase of the EPSP revealed voltage dependence characteristic to the responses mediated by N-methyl-D-aspartate (NMDA) receptors and was depressed by application of an NMDA antagonist DL-2-amino-5-phosphonovalerate (APV), whereas the rising phase of the EPSP was insensitive to APV. 3. The early EPSPs followed by IPSPs were insensitive to APV but were replaced with a slow depolarizing potential by application of a non-NMDA antagonist 6,7-dinitro-quinoxaline-2,3-dione (DNQX), indicating that the early EPSP is mediated by non-NMDA receptors. The slow depolarization was mediated by NMDA receptors because it was depressed by membrane hyperpolarization or addition of APV. 4. The late EPSP evoked by higher-frequency stimulation was abolished by APV, indicating that it is mediated by NMDA receptors, which are located either on the recorded cell or on presynaptic cells to the recorded cells. 5. Long-term potentiation (LTP) of EPSPs was examined in cells perfused with solutions containing 1 microM bicuculline methiodide (BIM), a gamma-aminobutyric acid (GABA) antagonist. WM was stimulated at 2 Hz for 15 min as a conditioning stimulus to induce LTP, and the resultant changes were tested by low-frequency (0.1 Hz) stimulation of WM. 6. LTP of early EPSPs occurred in more than one-half of the cells (8/13) after strong conditioning stimulation. The rising slope of the EPSP was increased 1.6 times on average. 7. To test involvement of NMDA receptors in the induction of LTP in the early EPSP, the effect of conditioning stimulation was studied in a solution containing 100 microM APV, which was sufficient to block completely synaptic transmission mediated by NMDA receptors. LTP occurred in the same frequency and magnitude as in control solution.

Download Full-text

Calcium-dependent inactivation of the monosynaptic NMDA EPSCs in rat hippocampal neurons in culture

European Journal of Neuroscience ◽

10.1046/j.1460-9568.1999.00664.x ◽

1999 ◽

Vol 11 (7) ◽

pp. 2422-2430 ◽

Cited By ~ 18

Author(s):

Igor Medina ◽

Xavier Leinekugel ◽

Yehezkel Ben-Ari

Keyword(s):

Hippocampal Neurons ◽

Calcium Dependent ◽

Dependent Inactivation

Download Full-text

Changes in Intracellular Calcium Concentration Affect Desensitization of GABAA Receptors in Acutely Dissociated P2–P6 Rat Hippocampal Neurons

Journal of Neurophysiology ◽

10.1152/jn.1998.79.3.1321 ◽

1998 ◽

Vol 79 (3) ◽

pp. 1321-1328 ◽

Cited By ~ 14

Author(s):

Jerzy W. Mozrzymas ◽

Enrico Cherubini

Keyword(s):

Intracellular Calcium ◽

Hippocampal Neurons ◽

Calcium Concentration ◽

Intracellular Calcium Concentration ◽

Potential Range ◽

Patch Clamp Technique ◽

Whole Cell ◽

Cell Configuration ◽

High Calcium ◽

Kinetics Of

Mozrzymas, Jerzy W. and Enrico Cherubini. Changes in intracellular calcium concentration affect desensitization of GABAA receptors in acutely dissociated P2–P6 rat hippocampal neurons. J. Neurophysiol. 79: 1321–1328, 1998. The whole cell configuration of the patch-clamp technique was used to study the effects of different cytosolic calcium concentrations [Ca2+]i on desensitization kinetics of γ-aminobutyric acid (GABA)-activated receptors in acutely dissociated rat hippocampal neurons. Two different intrapipette concentrations of the calcium chelator 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid (BAPTA; 11 and 0.9 mM, respectively) were used to yield a low (1.2 × 10−8 M) or a high (2.2 × 10−6 M) [Ca2+]i. In low [Ca2+]i, peak values of GABA-evoked currents (20 μM) evoked at −30 mV, were significantly larger than those recorded in high calcium [2,970 ± 280 (SE) pA vs. 1,870 ± 150 pA]. The extent of desensitization, assessed from steady-state to peak ratio was significantly higher in high calcium conditions (0.14 ± 0.007 vs. 0.11 ± 0.008). Similar effects of [Ca2+]i on desensitization were observed with GABA (100 μM). Recovery from desensitization, measured at 30 s interval with double pulse protocol was significantly slower in high [Ca2+]i than in low [Ca2+]i (54 ± 3% vs. 68 ± 2%). The current-voltage relationship of GABA-evoked currents was linear in the potential range between −50 and 50 mV. The kinetics of desensitization process including the rate of onset, extent of desensitization, and recovery were voltage independent. The run down of GABA-evoked currents was faster with the higher intracellular calcium concentration. The run down process was accompanied by changes in desensitization kinetics: in both high and low [Ca2+]i desensitization rate was progressively increasing with time as the slow component of the desensitization onset was converted into the fast one. In excised patches, the desensitization kinetics was much faster and more profound than in the whole cell configuration, indicating the involvement of intracellular factors in regulation of this process. In conclusion, [Ca2+]i affects the desensitization of GABAA receptors possibly by activating calcium-dependent enzymes that regulate their phosphorylation state. This may lead to modifications in cell excitability because of changes in GABA-mediated synaptic currents.

Download Full-text

Novel glycine-dependent inactivation of NMDA receptors in cultured hippocampal neurons

Neuroscience Bulletin ◽

10.1007/s12264-012-1266-y ◽

2012 ◽

Vol 28 (5) ◽

pp. 550-560 ◽

Cited By ~ 5

Author(s):

Yun-Feng Zhang ◽

Xia Li ◽

Liang-Liang Peng ◽

Guo-Hua Wang ◽

Kai-Fu Ke ◽

...

Keyword(s):

Nmda Receptors ◽

Hippocampal Neurons ◽

Dependent Inactivation ◽

Cultured Hippocampal Neurons

Download Full-text

Activity-dependent increases in [Ca2+]i contribute to digital-analog plasticity at a molluscan synapse

Journal of Neurophysiology ◽

10.1152/jn.00034.2017 ◽

2017 ◽

Vol 117 (6) ◽

pp. 2104-2112 ◽

Cited By ~ 5

Author(s):

Bjoern Ch. Ludwar ◽

Colin G. Evans ◽

Monica Cambi ◽

Elizabeth C. Cropper

Keyword(s):

Synaptic Transmission ◽

Intracellular Calcium ◽

Time Constant ◽

Calcium Concentration ◽

Low Frequency ◽

Intracellular Calcium Concentration ◽

Calcium Signal ◽

Presynaptic Neuron ◽

Calcium Dependent ◽

Long Time

In a type of short-term plasticity that is observed in a number of systems, synaptic transmission is potentiated by depolarizing changes in the membrane potential of the presynaptic neuron before spike initiation. This digital-analog form of plasticity is graded. The more depolarized the neuron, the greater the increase in the efficacy of synaptic transmission. In a number of systems, including the system presently under investigation, this type of modulation is calcium dependent, and its graded nature is presumably a consequence of a direct relationship between the intracellular calcium concentration ([Ca2+]i) and the effect on synaptic transmission. It is therefore of interest to identify factors that determine the magnitude of this type of calcium signal. We studied a synapse in Aplysia and demonstrate that there can be a contribution from currents activated during spiking. When neurons spike, there are localized increases in [Ca2+]i that directly trigger neurotransmitter release. Additionally, spiking can lead to global increases in [Ca2+]i that are reminiscent of those induced by subthreshold depolarization. We demonstrate that these spike-induced increases in [Ca2+]i result from the activation of a current not activated by subthreshold depolarization. Importantly, they decay with a relatively slow time constant. Consequently, with repeated spiking, even at a low frequency, they readily summate to become larger than increases in [Ca2+]i induced by subthreshold depolarization alone. When this occurs, global increases in [Ca2+]i induced by spiking play the predominant role in determining the efficacy of synaptic transmission. NEW & NOTEWORTHY We demonstrate that spiking can induce global increases in the intracellular calcium concentration ([Ca2+]i) that decay with a relatively long time constant. Consequently, summation of the calcium signal occurs even at low firing frequencies. As a result there is significant, persistent potentiation of synaptic transmission.

Download Full-text

Synaptic and Extrasynaptic NMDA Receptor NR2 Subunits in Cultured Hippocampal Neurons

Journal of Neurophysiology ◽

10.1152/jn.00771.2005 ◽

2006 ◽

Vol 95 (3) ◽

pp. 1727-1734 ◽

Cited By ~ 186

Author(s):

Christopher G. Thomas ◽

Ashleigh J. Miller ◽

Gary L. Westbrook

Keyword(s):

Nmda Receptors ◽

Hippocampal Neurons ◽

Synapse Formation ◽

Whole Cell ◽

Extrasynaptic Receptors ◽

C Terminus ◽

Specific Antagonist ◽

Nr2 Subunits ◽

Cultured Hippocampal Neurons

Early in development, neurons only express NR1/NR2B-containing N-methyl-d-aspartate (NMDA) receptors. Later, NR2A subunits are upregulated during a period of rapid synapse formation. This pattern is often interpreted to indicate that NR2A-containing receptors are synaptic and that NR2B-containing receptors are extrasynaptic. We re-examined this issue using whole cell recordings in cultured hippocampal neurons. As expected, the inhibition of whole cell currents by the NR2B-specific antagonist, ifenprodil, progressively decreased from 69.5 ± 2.4% [6 days in vitro (DIV)] to 54.9 ± 2.6% (8 DIV), before reaching a plateau in the second week (42.5 ± 2%, 12–19 DIV). In NR2A−/− neurons, which express only NR1/NR2B-containing NMDA receptors, autaptic excitatory postsynaptic currents (EPSCs; ≥12 DIV) were more sensitive to ifenprodil and decayed more slowly than EPSCs in wild-type neurons. Thus NR2B-containing receptors were not excluded from synapses. We blocked synaptic NMDA receptors with MK-801 during evoked transmitter release, thus allowing us to isolate extrasynaptic receptors. Ifenprodil inhibition of this extrasynaptic population was highly variable in different neurons. Furthermore, extrasynaptic receptors in autaptic cultures were only partially blocked by ifenprodil, indicating that NR2A-containing receptors are not exclusively confined to the synapse. Extrasynaptic NR2A-containing receptors were also detected in NR2A−/− neurons transfected with full-length NR2A. Truncation of the NR2A C terminus did not eliminate synaptic expression of NR2A-containing receptors. Our results indicate that NR2A- and NR2B-containing receptors can be located in either synaptic or extrasynaptic compartments.

Download Full-text

The effect of weak low-frequency magnetic fields on the intracellular calcium-dependent proteinases of fish

Biology Bulletin ◽

10.1134/s1062359013060071 ◽

2013 ◽

Vol 40 (6) ◽

pp. 515-518 ◽

Cited By ~ 3

Author(s):

N. P. Kantserova ◽

N. V. Ushakova ◽

V. V. Krylov ◽

L. A. Lysenko ◽

N. N. Nemova

Keyword(s):

Magnetic Fields ◽

Intracellular Calcium ◽

Low Frequency ◽

Calcium Dependent

Download Full-text

BDNF Modulation of NMDA Receptors Is Activity Dependent

Journal of Neurophysiology ◽

10.1152/jn.90418.2008 ◽

2008 ◽

Vol 100 (6) ◽

pp. 3264-3274 ◽

Cited By ~ 38

Author(s):

Robert A. Crozier ◽

Caixia Bi ◽

Yu R. Han ◽

Mark R. Plummer

Keyword(s):

Nmda Receptors ◽

High Frequency ◽

Hippocampal Neurons ◽

Single Channel ◽

Low Frequency ◽

Channel Activity ◽

Synaptic Specificity ◽

Active Channels ◽

Activity Dependent ◽

Postsynaptic Mechanism

Brain-derived neurotrophic factor (BDNF), a potent modulator of synaptic transmission, is known to influence associative synaptic plasticity and refinement of neural connectivity. We now show that BDNF modulation of glutamate currents in hippocampal neurons exhibits the additional property of use dependence, a postsynaptic mechanism resulting in selective modulation of active channels. We demonstrate selectivity by varying the repetition rate of iontophoretically applied glutamate pulses during BDNF exposure. During relatively high-frequency glutamate pulses (0.1 Hz), BDNF application elicited a doubling of the glutamate current. During low-frequency pulses (0.0033 Hz), however, BDNF evoked a dramatically diminished response. This effect was apparently mediated by calcium because manipulations that prevented elevation of intracellular calcium largely eliminated the action of BDNF on glutamate currents. To confirm N-methyl-d-aspartate (NMDA) receptor involvement and assess spatial requirements, we made cell-attached single-channel recordings from somatic NMDA receptors. Inclusion of calcium in the pipette was sufficient to produce enhancement of channel activity by BDNF. Substitution of EGTA for calcium prevented BDNF effects. We conclude that BDNF modulation of postsynaptic NMDA receptors requires concurrent neuronal activity potentially conferring synaptic specificity on the neurotrophin's actions.

Download Full-text