Synaptic Activation of Dendritic AMPA and NMDA Receptors Generates Transient High-Frequency Firing in Substantia Nigra Dopamine Neurons In Vitro

2007 ◽  
Vol 97 (4) ◽  
pp. 2837-2850 ◽  
Author(s):  
Sarah N. Blythe ◽  
Jeremy F. Atherton ◽  
Mark D. Bevan
Keyword(s):  
Nmda Receptor ◽  
Substantia Nigra ◽  
Action Potential ◽  
Nmda Receptors ◽  
High Frequency ◽  
Brain Slices ◽  
Dopamine Neurons ◽  
Frequency Pattern ◽  
High Frequency Activity ◽  
Evoked Activity

Transient high-frequency activity of substantia nigra dopamine neurons is critical for striatal synaptic plasticity and associative learning. However, the mechanisms underlying this mode of activity are poorly understood because, in contrast to other rapidly firing neurons, high-frequency activity is not evoked by somatic current injection. Previous studies have suggested that activation of dendritic N-methyl-d-aspartate (NMDA) receptors and/or G-protein-coupled receptor (GPCR)-mediated reduction of action potential afterhyperpolarization and/or activation of cation channels underlie high-frequency activity. To address their relative contribution, transient high-frequency activity was evoked using local electrical stimulation (1 s, 10–100 Hz) in brain slices prepared from p15–p25 rats in the presence of GABA and D2 dopamine receptor antagonists. The frequency, pattern, and morphology of action potentials evoked under these conditions were similar to those observed in vivo. Evoked activity and reductions in action potential afterhyperpolarization were diminished greatly by application of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) or NMDA receptor selective antagonists and abolished completely by co-application of AMPA and NMDA antagonists. In contrast, application of glutamatergic and cholinergic GPCR antagonists moderately enhanced evoked activity. Dendritic pressure-pulse application of glutamate evoked high-frequency activity that was similarly sensitive to antagonism of AMPA or NMDA receptors. Taken together, these data suggest that dendritic AMPA and NMDA receptor-mediated synaptic conductances are sufficient to generate transient high-frequency activity in substantia nigra dopamine neurons by rapidly but transiently overwhelming the conductances underlying action potential afterhyperpolarization and/or engaging postsynaptic voltage-dependent ion channels in a manner that overcomes the limiting effects of afterhyperpolarization.

scholarly journals N-Methyl-D-aspartate (NMDA) and cannabinoid CB2 receptors form functional complexes in cells of the central nervous system: insights into the therapeutic potential of neuronal and microglial NMDA receptors

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Rafael Rivas-Santisteban ◽  
Alejandro Lillo ◽  
Jaume Lillo ◽  
Joan-Biel Rebassa ◽  
Joan S. Contestí ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Nmda Receptor ◽  
Transgenic Mice ◽  
Nmda Receptors ◽  
Mapk Pathway ◽  
Primary Cultures ◽  
Brain Slices ◽  
Receptor Complexes ◽  
Receptor Heteromers

Abstract Background The cannabinoid CB2 receptor (CB2R), which is a target to afford neuroprotection, and N-methyl-D-aspartate (NMDA) ionotropic glutamate receptors, which are key in mediating excitatory neurotransmission, are expressed in both neurons and glia. As NMDA receptors are the target of current medication in Alzheimer’s disease patients and with the aim of finding neuromodulators of their actions that could provide benefits in dementia, we hypothesized that cannabinoids could modulate NMDA function. Methods Immunocytochemistry was used to analyze the colocalization between CB2 and NMDA receptors; bioluminescence resonance energy transfer was used to detect CB2-NMDA receptor complexes. Calcium and cAMP determination, mitogen-activated protein kinase (MAPK) pathway activation, and label-free assays were performed to characterize signaling in homologous and heterologous systems. Proximity ligation assays were used to quantify CB2-NMDA heteromer expression in mouse primary cultures and in the brain of APPSw/Ind transgenic mice, an Alzheimer’s disease model expressing the Indiana and Swedish mutated version of the human amyloid precursor protein (APP). Results In a heterologous system, we identified CB2-NMDA complexes with a particular heteromer print consisting of impairment by cannabinoids of NMDA receptor function. The print was detected in activated primary microglia treated with lipopolysaccharide and interferon-γ. CB2R activation blunted NMDA receptor-mediated signaling in primary hippocampal neurons from APPSw/Ind mice. Furthermore, imaging studies showed that in brain slices and in primary cells (microglia or neurons) from APPSw/Ind mice, there was a marked overexpression of macromolecular CB2-NMDA receptor complexes thus becoming a tool to modulate excessive glutamate input by cannabinoids. Conclusions The results indicate a negative cross-talk in CB2-NMDA complexes signaling. The expression of the CB2-NMDA receptor heteromers increases in both microglia and neurons from the APPSw/Ind transgenic mice, compared with levels in samples from age-matched control mice.

Resilient RTN Fast Spiking in Kv3.1 Null Mice Suggests Redundancy in the Action Potential Repolarization Mechanism

2002 ◽  
Vol 87 (3) ◽  
pp. 1303-1310 ◽  
Author(s):  
Darrell M. Porcello ◽  
Chi Shun Ho ◽  
Rolf H. Joho ◽  
John R. Huguenard
Keyword(s):  
Action Potential ◽  
High Frequency ◽  
Action Potentials ◽  
Brain Slices ◽  
Firing Frequency ◽  
Wild Type ◽  
Genetic Redundancy ◽  
Fast Spiking ◽  
Deficient Mice ◽  
Action Potential Repolarization

Fast spiking (FS), GABAergic neurons of the reticular thalamic nucleus (RTN) are capable of firing high-frequency trains of brief action potentials, with little adaptation. Studies in recombinant systems have shown that high-voltage-activated K+ channels containing the Kv3.1 and/or Kv3.2 subunits display biophysical properties that may contribute to the FS phenotype. Given that RTN expresses high levels of Kv3.1, with little or no Kv3.2, we tested whether this subunit was required for the fast action potential repolarization mechanism essential to the FS phenotype. Single- and multiple-action potentials were recorded using whole-cell current clamp in RTN neurons from brain slices of wild-type and Kv3.1-deficient mice. At 23°C, action potentials recorded from homozygous Kv3.1 deficient mice (Kv3.1−/−) compared with their wild-type (Kv3.1+/+) counterparts had reduced amplitudes (−6%) and fast after-hyperpolarizations (−16%). At 34°C, action potentials in Kv3.1−/− mice had increased duration (21%) due to a reduced rate of repolarization (−30%) when compared with wild-type controls. Action potential trains in Kv3.1−/− were associated with a significantly greater spike decrement and broadening and a diminished firing frequency versus injected current relationship ( F/I) at 34°C. There was no change in either spike count or maximum instantaneous frequency during low-threshold Ca2+ bursts in Kv3.1−/− RTN neurons at either temperature tested. Our findings show that Kv3.1 is not solely responsible for fast spikes or high-frequency firing in RTN neurons. This suggests genetic redundancy in the system, possibly in the form of other Kv3 members, which may suffice to maintain the FS phenotype in RTN neurons in the absence of Kv3.1.

Corticostriatal Paired-Pulse Potentiation Produced by Voltage-Dependent Activation of NMDA Receptors and L-Type Ca2+ Channels

2002 ◽  
Vol 87 (1) ◽  
pp. 157-165 ◽  
Author(s):  
Garnik Akopian ◽  
John P. Walsh
Keyword(s):  
Nmda Receptor ◽  
Nmda Receptors ◽  
Ampa Receptor ◽  
Brain Slices ◽  
Cell Voltage ◽  
Excitatory Postsynaptic Currents ◽  
Paired Pulse ◽  
Stimulation Intensity ◽  
Postsynaptic Currents ◽  
Voltage Dependent

AMPA and N-methyl-d-aspartate (NMDA) receptor-mediated synaptic responses expressed differential paired-pulse plasticity when examined in the same cell using intracellular or whole cell voltage-clamp recordings. Electrical stimulation of corticostriatal afferents in brain slices bathed in artificial cerebrospinal fluid containing bicuculline produces excitatory postsynaptic potentials and excitatory postsynaptic currents (EPSCs) mediated primarily by AMPA receptors. Cell-to-cell variation existed in AMPA receptor paired-pulse plasticity, but within-cell plasticity was stable over a range of stimulation intensities. Addition of 6-cyano-7-nitroquinoxalene-2,3-dione blocked most of the synaptic response leaving behind a small AP-5-sensitive component. Increasing the stimulation intensity produced large, long-lasting NMDA receptor-mediated responses. In contrast to AMPA receptor-mediated responses, NMDA receptor responses consistently showed an increase in paired-pulse potentiation with increasing stimulation intensity. This relationship was restricted to interstimulus intervals shorter than 100 ms. Paired-pulse potentiation of NMDA receptor responses was voltage-dependent and reduced by removal of extracellular Mg2+. Block of postsynaptic L-type Ca2+ channels with nifedipine produced a voltage-dependent reduction of NMDA receptor excitatory postsynaptic currents (EPSCs) and a voltage-dependent reduction of NMDA receptor paired-pulse potentiation. These data indicate depolarization during the first NMDA receptor response causes facilitation of the second by removing voltage-dependent block of NMDA receptors by Mg2+ and by activating voltage-dependent Ca2+ channels.

scholarly journals Xenon Attenuates Hippocampal Long-term Potentiation by Diminishing Synaptic and Extrasynaptic N -methyl-D-aspartate Receptor Currents

2012 ◽  
Vol 116 (3) ◽  
pp. 673-682 ◽  
Author(s):  
Stephan Kratzer ◽  
Corinna Mattusch ◽  
Eberhard Kochs ◽  
Matthias Eder ◽  
Rainer Haseneder ◽  
...  
Keyword(s):  
Nmda Receptor ◽  
High Frequency ◽  
Brain Slices ◽  
Long Term Potentiation ◽  
High Frequency Stimulation ◽  
Field Potentials ◽  
Aspartate Receptor ◽  
Term Potentiation ◽  
Frequency Stimulation

Background The memory-blocking properties of general anesthetics are of high clinical relevance and scientific interest. The inhalational anesthetic xenon antagonizes N-methyl-D-aspartate (NMDA) receptors. It is unknown if xenon affects long-term potentiation (LTP), a cellular correlate for memory formation. In hippocampal brain slices, the authors investigated in area CA1 whether xenon affects LTP, NMDA receptor-mediated neurotransmission, and intracellular calcium concentrations. Methods In sagittal murine hippocampal brain slices, the authors investigated the effects of xenon on LTP by recording excitatory postsynaptic field potentials. Using fluorometric calcium imaging, the authors tested the influence of xenon on calcium influx during high-frequency stimulation. In addition, using the patch-clamp technique, the xenon effect on synaptic and extrasynaptic NMDA receptors and L-type calcium channels was examined. Results In the absence of xenon, high-frequency stimulation reliably induced LTP and potentiated field potential slopes to (mean ± SEM) 127.2 ± 5.8% (P < 0.001). In the presence of xenon, high-frequency stimulation induced only a short-term potentiation, and field potentials returned to baseline level after 15-20 min (105.9 ± 2.9%; P = 0.090). NMDA receptor-mediated excitatory postsynaptic currents were reduced reversibly by xenon to 65.9 ± 9.4% (P = 0.007) of control. When extrasynaptic receptors were activated, xenon decreased NMDA currents to 58.2 ± 5.8% (P < 0.001). Xenon reduced the increase in intracellular calcium during high-frequency stimulation without affecting L-type calcium channels. Conclusions N-methyl-D-aspartate receptor activation is crucial for the induction of CA1 LTP. Thus, the depression of NMDA receptor-mediated neurotransmission presumably contributes to the blockade of LTP under xenon. Because LTP is assumed to be involved in learning and memory, its blockade might be a key mechanism for xenon's amnestic properties.

Differential Roles of NMDA and Non-NMDA Receptors in Synaptic Responses of Neurons in Nucleus Tractus Solitarii of the Rat

1999 ◽  
Vol 81 (6) ◽  
pp. 3034-3043 ◽  
Author(s):  
J. C. Yen ◽  
Julie Y. H. Chan ◽  
Samuel H. H. Chan
Keyword(s):  
Nmda Receptor ◽  
Action Potential ◽  
Nmda Receptors ◽  
Nucleus Tractus Solitarii ◽  
The Other ◽  
Synaptic Response ◽  
Nmda Receptor Subunits ◽  
Single Action ◽  
Other Hand ◽  
Synaptic Responses

Differential roles of NMDA and non-NMDA receptors in synaptic responses of neurons in nucleus tractus solitarii of the rat. The relative role of N-methyl-d-aspartate (NMDA) and non-NMDA receptors in synaptic responses of neurons in caudal nucleus tractus solitarii (cNTS) was delineated by immunohistochemical and electrophysiologic experiments in rats. Double immunohistochemical staining in in vivo experiments revealed that ∼80% of cNTS neurons that showed Fos-like immunoreactivity induced by baroreceptor activation were generally also immunoreactive to non-NMDA receptor subunits GluR1 or GluR2. On the other hand, only 20% of Fos-labeled cNTS neurons showed immunoreactivity to NMDA receptor subunits NMDAR1 or NMDAR2. Stimulation of the ipsilateral solitary tract at suprathreshold intensity in slice preparations induced Fos expression in the cNTS and evoked either a single action potential or a complex synaptic response consisting of an initial action potential followed by a secondary slow depolarization. In a majority (70%) of cNTS neurons that exhibited the complex synaptic response, both the initial and secondary components were eliminated reversibly by 6-cyano-7-nitroquinoxaline-2,3-dione (20 μM). This non-NMDA antagonist also inhibited the single action potential manifested by the other population of cNTS neurons. On the other hand, only the secondary slow depolarization was blocked byd(−)-2-amino-5-phosphonopentanoic acid (250 μM) or potentiated by NMDA (1.7 μM). Our results suggested that NMDA and non-NMDA receptors are involved differentially in the synaptic responses of cNTS neurons. Non-NMDA receptors may be distributed predominantly on a majority of the second-order cNTS neurons that may receive primary baroreceptor afferent inputs. On the other hand, NMDA receptors are located primarily on higher-order neurons, which may be connected reciprocally with the second-order cNTS neurons.

Persistent elevation of D-Aspartate enhances NMDA receptor-mediated responses in mouse substantia nigra pars compacta dopamine neurons

2016 ◽  
Vol 103 ◽  
pp. 69-78 ◽  
Author(s):  
Paraskevi Krashia ◽  
Ada Ledonne ◽  
Annalisa Nobili ◽  
Alberto Cordella ◽  
Francesco Errico ◽  
...  
Keyword(s):  
Nmda Receptor ◽  
Substantia Nigra ◽  
Dopamine Neurons ◽  
Substantia Nigra Pars Compacta ◽  
Persistent Elevation

scholarly journals Hyperexcitable Substantia Nigra Dopamine Neurons in PINK1- and HtrA2/Omi-Deficient Mice

2010 ◽  
Vol 104 (6) ◽  
pp. 3009-3020 ◽  
Author(s):  
Matthew W. Bishop ◽  
Subhojit Chakraborty ◽  
Gillian A. C. Matthews ◽  
Antonios Dougalis ◽  
Nicholas W. Wood ◽  
...  
Keyword(s):  
Substantia Nigra ◽  
Brain Slices ◽  
Selective Vulnerability ◽  
Dopamine Neurons ◽  
Substantia Nigra Pars Compacta ◽  
Electrophysiological Properties ◽  
Irregular Pattern ◽  
Functional Reduction ◽  
Small Conductance

The electrophysiological properties of substantia nigra pars compacta (SNC) dopamine neurons can influence their susceptibility to degeneration in toxin-based models of Parkinson's disease (PD), suggesting that excitotoxic and/or hypoactive mechanisms may be engaged during the early stages of the disease. It is unclear, however, whether the electrophysiological properties of SNC dopamine neurons are affected by genetic susceptibility to PD. Here we show that deletion of PD-associated genes, PINK1 or HtrA2/Omi, leads to a functional reduction in the activity of small-conductance Ca2+-activated potassium channels. This reduction causes SNC dopamine neurons to fire action potentials in an irregular pattern and enhances burst firing in brain slices and in vivo. In contrast, PINK1 deletion does not affect firing regularity in ventral tegmental area dopamine neurons or substantia nigra pars reticulata GABAergic neurons. These findings suggest that changes in SNC dopamine neuron excitability may play a role in their selective vulnerability in PD.

scholarly journals Substantia nigra dopamine neurons evoke a delayed excitation in lateral dorsal striatal cholinergic interneurons via glutamate cotransmission

2018 ◽  
Author(s):  
Nao Chuhma ◽  
Susana Mingote ◽  
Leora Yetnikoff ◽  
Abigail Kalmbach ◽  
Thong Ma ◽  
...  
Keyword(s):  
Substantia Nigra ◽  
Transient Receptor Potential ◽  
Metabotropic Glutamate Receptor ◽  
Brain Slices ◽  
Dorsal Striatum ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Dopamine Neurons ◽  
Projection Neurons ◽  
Cholinergic Interneurons

SummaryDopamine neurons have different synaptic actions in the ventral and dorsal striatum (dStr), but whether this heterogeneity extends to dStr subregions has not been addressed. We have found that optogenetic activation of dStr dopamine neuron terminals in mouse brain slices pauses the firing of cholinergic interneurons in both the medial and lateral subregions, while in the lateral subregion the pause is shorter due to a subsequent excitation. This excitation is mediated mainly by metabotropic glutamate receptor 1 (mGluR1) and partially by dopamine D1-like receptors coupled to transient receptor potential channel 3 and 7. DA neurons do not signal to spiny projection neurons in the medial dStr, while they elicit ionotropic glutamate responses in the lateral dStr. The DA neurons mediating these excitatory signals are in the substantia nigra (SN). Thus, SN dopamine neurons engage different receptors in different postsynaptic neurons in different dStr subregions to convey strikingly different signals.

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