scholarly journals Glutamatergic synapses in the rat nucleus tractus solitarii develop by direct insertion of calcium-impermeable AMPA receptors and without activation of NMDA receptors

2006 ◽  
Vol 574 (1) ◽  
pp. 245-261 ◽  
Author(s):  
Bénédicte Balland ◽  
Philippe Lachamp ◽  
Caroline Strube ◽  
Jean-Pierre Kessler ◽  
Fabien Tell
Keyword(s):  
Nmda Receptors ◽  
Ampa Receptors ◽  
Nucleus Tractus Solitarii ◽  
Glutamatergic Synapses

scholarly journals Metaplastic Effects of Ketamine and MK-801 on Glutamate Receptors Expression in Rat Medial Prefrontal Cortex and Hippocampus

2021 ◽  
Author(s):  
Alessandro Piva ◽  
Lucia Caffino ◽  
Francesca Mottarlini ◽  
Nicholas Pintori ◽  
Fernando Castillo Díaz ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Nmda Receptors ◽  
Glutamate Receptors ◽  
Medial Prefrontal Cortex ◽  
Ampa Receptors ◽  
Glutamate Transporter ◽  
Fine Tuning ◽  
Scaffolding Proteins ◽  
Glutamatergic Synapses ◽  
Mk 801

AbstractKetamine and MK-801 by blocking NMDA receptors may induce reinforcing effects as well as schizophrenia-like symptoms. Recent results showed that ketamine can also effectively reverse depressive signs in patients’ refractory to standard therapies. This evidence clearly points to the need of characterization of effects of these NMDARs antagonists on relevant brain areas for mood disorders. The aim of the present study was to investigate the molecular changes occurring at glutamatergic synapses 24 h after ketamine or MK-801 treatment in the rat medial prefrontal cortex (mPFC) and hippocampus (Hipp). In particular, we analyzed the levels of the glutamate transporter-1 (GLT-1), NMDA receptors, AMPA receptors subunits, and related scaffolding proteins. In the homogenate, we found a general decrease of protein levels, whereas their changes in the post-synaptic density were more complex. In fact, ketamine in the mPFC decreased the level of GLT-1 and increased the level of GluN2B, GluA1, GluA2, and scaffolding proteins, likely indicating a pattern of enhanced excitability. On the other hand, MK-801 only induced sparse changes with apparently no correlation to functional modification. Differently from mPFC, in Hipp, both substances reduced or caused no changes of glutamate receptors and scaffolding proteins expression. Ketamine decreased NMDA receptors while increased AMPA receptors subunit ratios, an effect indicative of permissive metaplastic modulation; conversely, MK-801 only decreased the latter, possibly representing a blockade of further synaptic plasticity. Taken together, these findings indicate a fine tuning of glutamatergic synapses by ketamine compared to MK-801 both in the mPFC and Hipp.

scholarly journals Pharmacological modulation of AMPA receptors rescues specific impairments in social behavior associated with the A350V Iqsec2 mutation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Renad Jabarin ◽  
Nina Levy ◽  
Yasmin Abergel ◽  
Joshua H. Berman ◽  
Amir Zag ◽  
...  
Keyword(s):  
Social Behavior ◽  
Ampa Receptors ◽  
Emotional State ◽  
Social Discrimination ◽  
Glutamatergic Synapses ◽  
Behavioral Deficits ◽  
Pharmacological Modulation ◽  
The Social ◽  
State Preference ◽  
Molecular Pathophysiology

AbstractIn this study we tested the hypothesis that pharmacological modulation of glutamatergic neurotransmission could rescue behavioral deficits exhibited by mice carrying a specific mutation in the Iqsec2 gene. The IQSEC2 protein plays a key role in glutamatergic synapses and mutations in the IQSEC2 gene are a frequent cause of neurodevelopmental disorders. We have recently reported on the molecular pathophysiology of one such mutation A350V and demonstrated that this mutation downregulates AMPA type glutamatergic receptors (AMPAR) in A350V mice. Here we sought to identify behavioral deficits in A350V mice and hypothesized that we could rescue these deficits by PF-4778574, a positive AMPAR modulator. Using a battery of social behavioral tasks, we found that A350V Iqsec2 mice exhibit specific deficits in sex preference and emotional state preference behaviors as well as in vocalizations when encountering a female mouse. The social discrimination deficits, but not the impaired vocalization, were rescued with a single dose of PF-4778574. We conclude that social behavior deficits associated with the A350V Iqsec2 mutation may be rescued by enhancing AMPAR mediated synaptic transmission.

scholarly journals Synaptic abnormalities and cytoplasmic glutamate receptor aggregates in contactin associated protein-like 2/Caspr2 knockout neurons

2015 ◽  
Vol 112 (19) ◽  
pp. 6176-6181 ◽  
Author(s):  
Olga Varea ◽  
Maria Dolores Martin-de-Saavedra ◽  
Katherine J. Kopeikina ◽  
Britta Schürmann ◽  
Hunter J. Fleming ◽  
...  
Keyword(s):  
Ampa Receptors ◽  
Knockout Mice ◽  
Copy Number Variations ◽  
Spine Density ◽  
Structured Illumination ◽  
Single Nucleotide Variants ◽  
Glutamatergic Synapses ◽  
Superresolution Microscopy ◽  
Synaptic Markers ◽  
Cellular Phenotypes

Central glutamatergic synapses and the molecular pathways that control them are emerging as common substrates in the pathogenesis of mental disorders. Genetic variation in the contactin associated protein-like 2 (CNTNAP2) gene, including copy number variations, exon deletions, truncations, single nucleotide variants, and polymorphisms have been associated with intellectual disability, epilepsy, schizophrenia, language disorders, and autism. CNTNAP2, encoded by Cntnap2, is required for dendritic spine development and its absence causes disease-related phenotypes in mice. However, the mechanisms whereby CNTNAP2 regulates glutamatergic synapses are not known, and cellular phenotypes have not been investigated in Cntnap2 knockout neurons. Here we show that CNTNAP2 is present in dendritic spines, as well as axons and soma. Structured illumination superresolution microscopy reveals closer proximity to excitatory, rather than inhibitory synaptic markers. CNTNAP2 does not promote the formation of synapses and cultured neurons from Cntnap2 knockout mice do not show early defects in axon and dendrite outgrowth, suggesting that CNTNAP2 is not required at this stage. However, mature neurons from knockout mice show reduced spine density and levels of GluA1 subunits of AMPA receptors in spines. Unexpectedly, knockout neurons show large cytoplasmic aggregates of GluA1. Here we characterize, for the first time to our knowledge, synaptic phenotypes in Cntnap2 knockout neurons and reveal a novel role for CNTNAP2 in GluA1 trafficking. Taken together, our findings provide insight into the biological roles of CNTNAP2 and into the pathogenesis of CNTNAP2-associated neuropsychiatric disorders.

scholarly journals Silent Synapses in Developing Rat Nucleus Tractus Solitarii Have AMPA Receptors

2008 ◽  
Vol 28 (18) ◽  
pp. 4624-4634 ◽  
Author(s):  
B. Balland ◽  
P. Lachamp ◽  
J.-P. Kessler ◽  
F. Tell
Keyword(s):  
Ampa Receptors ◽  
Nucleus Tractus Solitarii ◽  
Silent Synapses ◽  
Developing Rat

scholarly journals Differential trafficking of AMPA receptors following activation of NMDA receptors and mGluRs

2011 ◽  
Vol 4 (1) ◽  
pp. 30 ◽  
Author(s):  
Thomas M Sanderson ◽  
Graham L Collingridge ◽  
Stephen M Fitzjohn
Keyword(s):  
Nmda Receptors ◽  
Ampa Receptors

Interaction of Dopamine D1 and NMDA Receptors Mediates Acute Clozapine Potentiation of Glutamate EPSPs in Rat Prefrontal Cortex

2002 ◽  
Vol 87 (5) ◽  
pp. 2324-2336 ◽  
Author(s):  
Long Chen ◽  
Charles R. Yang
Keyword(s):  
Prefrontal Cortex ◽  
Nmda Receptor ◽  
Nmda Receptors ◽  
Receptor Antagonist ◽  
Ampa Receptors ◽  
Nmda Receptor Antagonist ◽  
D1 Receptor ◽  
Resting Membrane Potential ◽  
Cellular Mechanisms ◽  
Cognitive Improvement

The atypical antipsychotic drug clozapine effectively alleviates both negative and positive symptoms of schizophrenia via unclear cellular mechanisms. Clozapine may modulate both glutamatergic and dopaminergic transmission in the prefrontal cortex (PFC) to achieve part of its therapeutic actions. Using whole cell patch-clamp techniques, current-clamp recordings in layers V–VI pyramidal neurons from rat PFC slices showed that stimulation of local afferents (in 2 μM bicuculline) evoked mixed [AMPA/kainate and N-methyl-d-aspartate (NMDA) receptors] glutamate receptor-mediated excitatory postsynaptic potentials (EPSPs). Clozapine (1 μM) potentiated polysynaptically mediated evoked EPSPs ( V Hold = −65 mV), or reversed EPSPs (rEPSP, V Hold = +20 mV) for >30 min. The potentiated EPSPs or rEPSPs were attenuated by elevating [Ca2+]O(7 mM), by application of NMDA receptor antagonist 2-amino5-phosphonovaleric acid (50 μM), or by pretreatment with dopamine D1/D5 receptor antagonist SCH23390 (1 μM) but could be further enhanced by a dopamine reuptake inhibitor bupropion (1 μM). Clozapine had no significant effect on pharmacologically isolated evoked NMDA-rEPSP or AMPA-rEPSPs but increased spontaneous EPSPs without changing the steady-state resting membrane potential. Under voltage clamp, clozapine (1 μM) enhanced the frequency, and the number of low-amplitude (5–10 pA) AMPA receptor-mediated spontaneous EPSCs, while there was no such changes with the mini-EPSCs (in 1 μM TTX). Taken together these data suggest that acute clozapine can increase spike-dependent presynaptic release of glutamate and dopamine. The glutamate stimulates distal dendritic AMPA receptors to increase spontaneous EPSCs and enabled a voltage-dependent activation of neuronal NMDA receptors. The dopamine released stimulates postsynaptic D1 receptor to modulate a lasting potentiation of the NMDA receptor component of the glutamatergic synaptic responses in the PFC neuronal network. This sequence of early synaptic events induced by acute clozapine may comprise part of the activity that leads to later cognitive improvement in schizophrenia.

scholarly journals IQSEC2-Associated Intellectual Disability and Autism

2019 ◽  
Vol 20 (12) ◽  
pp. 3038 ◽  
Author(s):  
Nina S. Levy ◽  
George K. E. Umanah ◽  
Eli J. Rogers ◽  
Reem Jada ◽  
Orit Lache ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Nmda Receptors ◽  
Glutamate Receptors ◽  
Ampa Receptor ◽  
Ampa Receptors ◽  
Neuronal Development ◽  
Catalytic Domain ◽  
Excitatory Synapses ◽  
Ampa Receptor Subunit ◽  
Ion Influx

Mutations in IQSEC2 cause intellectual disability (ID), which is often accompanied by seizures and autism. A number of studies have shown that IQSEC2 is an abundant protein in excitatory synapses and plays an important role in neuronal development as well as synaptic plasticity. Here, we review neuronal IQSEC2 signaling with emphasis on those aspects likely to be involved in autism. IQSEC2 is normally bound to N-methyl-D-aspartate (NMDA)-type glutamate receptors via post synaptic density protein 95 (PSD-95). Activation of NMDA receptors results in calcium ion influx and binding to calmodulin present on the IQSEC2 IQ domain. Calcium/calmodulin induces a conformational change in IQSEC2 leading to activation of the SEC7 catalytic domain. GTP is exchanged for GDP on ADP ribosylation factor 6 (ARF6). Activated ARF6 promotes downregulation of surface α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors through a c-jun N terminal kinase (JNK)-mediated pathway. NMDA receptors, AMPA receptors, and PSD-95 are all known to be adversely affected in autism. An IQSEC2 transgenic mouse carrying a constitutively active mutation (A350V) shows autistic features and reduced levels of surface AMPA receptor subunit GluA2. Sec7 activity and AMPA receptor recycling are presented as two targets, which may respond to drug treatment in IQSEC2-associated ID and autism.

scholarly journals Astrocytic modulation of glutamatergic synaptic transmission is reduced in NTS of rats submitted to short-term sustained hypoxia

2019 ◽  
Vol 121 (5) ◽  
pp. 1822-1830 ◽  
Author(s):  
Daniela Accorsi-Mendonça ◽  
Leni G. H. Bonagamba ◽  
Benedito H. Machado
Keyword(s):  
Synaptic Transmission ◽  
Ampa Receptors ◽  
Nucleus Tractus Solitarii ◽  
Resting Membrane Potential ◽  
Density Control ◽  
Glutamatergic Synaptic Transmission ◽  
Nmda Current ◽  
New Findings ◽  
Sustained Hypoxia ◽  
Respiratory Responses

Sustained hypoxia (SH) activates chemoreceptors to produce cardiovascular and respiratory responses to bring the arterial partial pressure of O2 back to the physiological range. We evaluated the effect of SH (fraction of inspired O2 = 0.10, 24 h) on glutamatergic synaptic transmission and the interaction neuron-astrocyte in neurons of the nucleus tractus solitarii (NTS). Tractus solitarius (TS) fiber stimulation induced glutamatergic currents in neurons and astrocytes. SH increased α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate (AMPA/kainate) [−183 ± 122 pA ( n = 10) vs. −353 ± 101 pA ( n = 10)] and N-methyl-d-aspartate (NMDA) current amplitude [61 ± 10 pA ( n = 7) vs. 102 ± 37 pA ( n = 10)]. To investigate the effects of SH, we used fluoroacetate (FAC), an astrocytic inhibitor, which revealed an excitatory modulation on AMPA/kainate current and an inhibitory modulation of NMDA current in control rats. SH blunted the astrocytic modulation of AMPA [artificial cerebrospinal fluid (aCSF): −353 ± 101 pA vs. aCSF + FAC: −369 ± 76 pA ( n = 10)] and NMDA currents [aCSF: 102 ± 37 pA vs. aCSF + FAC: 108 ± 32 pA ( n = 10)]. SH increased AMPA current density [control: −6 ± 3.5 pA/pF ( n = 6) vs. SH: −20 ± 12 pA/pF ( n = 7)], suggesting changes in density, conductance, or affinity of AMPA receptors. SH produced no effect on astrocytic resting membrane potential, input resistance, and AMPA/kainate current. We conclude that SH decreased the neuron-astrocyte interaction at the NTS level, facilitating the glutamatergic transmission, which may contribute to the enhancement of cardiovascular and respiratory responses to baro- and chemoreflexes activation in SH rats. NEW & NOTEWORTHY Using an electrophysiological approach, we have shown that in nucleus tractus solitarii (NTS) from control rats, astrocytes modulate the AMPA and NMDA currents in NTS neurons, changing their excitability. Sustained hypoxia (SH) increased both glutamatergic currents in NTS neurons due to 1) a reduction in the astrocytic modulation and 2) an increase in the density of AMPA receptors. These new findings show the importance of neuron-astrocyte modulation in the excitatory synaptic transmission in NTS of control and SH rats.

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