scholarly journals Psychosocial Crowding Stress-Induced Changes in Synaptic Transmission and Glutamate Receptor Expression in the Rat Frontal Cortex

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 294
Author(s):  
Agnieszka Zelek-Molik ◽  
Bartosz Bobula ◽  
Anna Gądek-Michalska ◽  
Katarzyna Chorązka ◽  
Adam Bielawski ◽  
...  
Keyword(s):  
Frontal Cortex ◽  
Primary Motor Cortex ◽  
Interleukin 1 ◽  
Field Potential ◽  
Long Term Potentiation ◽  
Plasma Corticosterone ◽  
Receptor Expression ◽  
Synaptic Activity ◽  
Common Mechanism ◽  
Crowding Stress

This study demonstrates how exposure to psychosocial crowding stress (CS) for 3, 7, and 14 days affects glutamate synapse functioning and signal transduction in the frontal cortex (FC) of rats. CS effects on synaptic activity were evaluated in FC slices of the primary motor cortex (M1) by measuring field potential (FP) amplitude, paired-pulse ratio (PPR), and long-term potentiation (LTP). Protein expression of GluA1, GluN2B mGluR1a/5, VGLUT1, and VGLUT2 was assessed in FC by western blot. The body’s response to CS was evaluated by measuring body weight and the plasma level of plasma corticosterone (CORT), adrenocorticotropic hormone (ACTH), and interleukin 1 beta (IL1B). CS 3 14d increased FP and attenuated LTP in M1, while PPR was augmented in CS 14d. The expression of GluA1, GluN2B, and mGluR1a/5 was up-regulated in CS 3d and downregulated in CS 14d. VGLUTs expression tended to increase in CS 7d. The failure to blunt the effects of chronic CS on FP and LTP in M1 suggests the impairment of habituation mechanisms by psychosocial stressors. PPR augmented by chronic CS with increased VGLUTs level in the CS 7d indicates that prolonged CS exposure changed presynaptic signaling within the FC. The CS bidirectional profile of changes in glutamate receptors’ expression seems to be a common mechanism evoked by stress in the FC.

scholarly journals Aging Alters Olfactory Bulb Network Oscillations and Connectivity: Relevance for Aging-Related Neurodegeneration Studies

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
A. Ahnaou ◽  
D. Rodriguez-Manrique ◽  
S. Embrechts ◽  
R. Biermans ◽  
N. V. Manyakov ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Memory Function ◽  
Field Potential ◽  
Long Term Potentiation ◽  
Synaptic Activity ◽  
High Frequency Stimulation ◽  
Excitatory Postsynaptic Potential ◽  
Histone H2ax ◽  
Aged Mice ◽  
Network Oscillations

The aging process eventually cause a breakdown in critical synaptic plasticity and connectivity leading to deficits in memory function. The olfactory bulb (OB) and the hippocampus, both regions of the brain considered critical for the processing of odors and spatial memory, are commonly affected by aging. Using an aged wild-type C57B/6 mouse model, we sought to define the effects of aging on hippocampal plasticity and the integrity of cortical circuits. Specifically, we measured the long-term potentiation of high-frequency stimulation (HFS-LTP) at the Shaffer-Collateral CA1 pyramidal synapses. Next, local field potential (LFP) spectra, phase-amplitude theta-gamma coupling (PAC), and connectivity through coherence were assessed in the olfactory bulb, frontal and entorhinal cortices, CA1, and amygdala circuits. The OB of aged mice showed a significant increase in the number of histone H2AX-positive neurons, a marker of DNA damage. While the input-output relationship measure of basal synaptic activity was found not to differ between young and aged mice, a pronounced decline in the slope of field excitatory postsynaptic potential (fEPSP) and the population spike amplitude (PSA) were found in aged mice. Furthermore, aging was accompanied by deficits in gamma network oscillations, a shift to slow oscillations, reduced coherence and theta-gamma PAC in the OB circuit. Thus, while the basal synaptic activity was unaltered in older mice, impairment in hippocampal synaptic transmission was observed only in response to HFS. However, age-dependent alterations in neural network appeared spontaneously in the OB circuit, suggesting the neurophysiological basis of synaptic deficits underlying olfactory processing. Taken together, the results highlight the sensitivity and therefore potential use of LFP quantitative network oscillations and connectivity at the OB level as objective electrophysiological markers that will help reveal specific dysfunctional circuits in aging-related neurodegeneration studies.

scholarly journals Effects of Antipsychotic Drugs and Potassium Channel Modulators on Cognition-related Local Field Potential Spectral Properties in Mouse Hippocampus and Frontal Cortex

2020 ◽  
Author(s):  
Dechuan Sun ◽  
Mojtaba Kermani ◽  
Matt Hudson ◽  
Xin He ◽  
Ranjith Rajasekharan Unnithan ◽  
...  
Keyword(s):  
Potassium Channel ◽  
Frontal Cortex ◽  
Local Field ◽  
Antipsychotic Drugs ◽  
Field Potential ◽  
Common Mechanism ◽  
Voltage Gated ◽  
Gamma Power ◽  
Potassium Channel Modulators ◽  
Phase Amplitude

AbstractLocal field potentials (LFPs) recorded intracranially display a range of location specific oscillatory spectra which have been related to cognitive processes. Although the exact mechanisms producing LFPs are not completely understood, it is likely that voltage-gated ion channels which produce action potentials and patterned discharges play a significant role. It is also known that antipsychotic drugs (APDs) affect LFPs spectra and a direct inhibitory effect on voltage-gated potassium (Kv) channels has been reported. Additionally, Kv channels have been implicated in the pathophysiology of schizophrenia, a disorder for which APDs are primary therapies. In this study we sought to: i) better characterise the effects of two APDs on LFPs and connectivity measures and ii) examine the effects of potassium channel modulators on LFPs and potential overlap of effects with APDs. Intracranial electrodes were implanted in the hippocampus (HIP) and pre-frontal cortex (PFC) of C57BL/6 mice; power spectra, coherence and phase-amplitude cross frequency coupling were measured. Drugs tested were the APDs haloperidol and clozapine as well as voltage-gated potassium channel modulators (KVMs) 4-aminopyridine(4AP), tetraethylammonium (TEA), E-4031 and retigabine. All drugs and vehicle controls were administered intraperitoneally. Both APDs and KVMs significantly reduced gamma power with the exception of 4AP, which conversely increased slow-gamma power. Clozapine and retigabine additionally reduced coherence between HIP and PFC. Phase-amplitude coupling between theta and gamma oscillations in HIP was significantly reduced by the administration of haloperidol and retigabine. These results provide previously undescribed effects of APDs on LFP properties and demonstrate novel modulation of LFP characteristics by KVMs that intriguingly overlaps with the effects of APDs. The possibility of a common mechanism of action deserves further study.

scholarly journals Sorting nexin-27 regulates AMPA receptor trafficking through the synaptic adhesion protein LRFN2

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Kirsty J McMillan ◽  
Paul J Banks ◽  
Francesca L N Hellel ◽  
Ruth E Carmichael ◽  
Thomas Clairfeuille ◽  
...  
Keyword(s):  
Ampa Receptor ◽  
Ampa Receptors ◽  
Long Term Potentiation ◽  
Receptor Expression ◽  
Synaptic Activity ◽  
Adhesion Protein ◽  
Endosomal Sorting ◽  
Sorting Nexin ◽  
Term Potentiation ◽  
Integral Proteins

The endosome-associated cargo adaptor sorting nexin-27 (SNX27) is linked to various neuropathologies through sorting of integral proteins to the synaptic surface, most notably AMPA receptors. To provide a broader view of SNX27-associated pathologies we performed proteomics in rat primary neurons to identify SNX27-dependent cargoes, and identified proteins linked to excitotoxicity, epilepsy, intellectual disabilities and working memory deficits. Focusing on the synaptic adhesion molecule LRFN2, we established that SNX27 binds to LRFN2 and regulates its endosomal sorting. Furthermore, LRFN2 associates with AMPA receptors and knockdown of LRFN2 results in decreased surface AMPA receptor expression, reduced synaptic activity, and attenuated hippocampal long-term potentiation. Overall, our study provides an additional mechanism by which SNX27 can control AMPA receptor-mediated synaptic transmission and plasticity indirectly through the sorting of LRFN2 and offers molecular insight into the perturbed function of SNX27 and LRFN2 in a range of neurological conditions.

scholarly journals Motor-Skill Learning Is Dependent on Astrocytic Activity

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Ragunathan Padmashri ◽  
Anand Suresh ◽  
Michael D. Boska ◽  
Anna Dunaevsky
Keyword(s):  
Motor Skill ◽  
Primary Motor Cortex ◽  
Skill Training ◽  
Long Term Potentiation ◽  
Skill Learning ◽  
Metabolic Inhibitor ◽  
Motor Skill Learning ◽  
Reaching Task ◽  
Learning Impairment

Motor-skill learning induces changes in synaptic structure and function in the primary motor cortex through the involvement of a long-term potentiation- (LTP-) like mechanism. Although there is evidence that calcium-dependent release of gliotransmitters by astrocytes plays an important role in synaptic transmission and plasticity, the role of astrocytes in motor-skill learning is not known. To test the hypothesis that astrocytic activity is necessary for motor-skill learning, we perturbed astrocytic function using pharmacological and genetic approaches. We find that perturbation of astrocytes either by selectively attenuating IP3R2 mediated astrocyte Ca2+signaling or using an astrocyte specific metabolic inhibitor fluorocitrate (FC) results in impaired motor-skill learning of a forelimb reaching-task in mice. Moreover, the learning impairment caused by blocking astrocytic activity using FC was rescued by administration of the gliotransmitter D-serine. The learning impairments are likely caused by impaired LTP as FC blocked LTP in slices and prevented motor-skill training-induced increases in synaptic AMPA-type glutamate receptorin vivo. These results support the conclusion that normal astrocytic Ca2+signaling during a reaching task is necessary for motor-skill learning.

Neurotrophins and Proneurotrophins: Focus on Synaptic Activity and Plasticity in the Brain

2017 ◽  
Vol 23 (6) ◽  
pp. 587-604 ◽  
Author(s):  
Julien Gibon ◽  
Philip A. Barker
Keyword(s):  
Long Term Potentiation ◽  
Synaptic Activity ◽  
Cellular Processes ◽  
Term Potentiation ◽  
Neurotrophin 3 ◽  
New Findings ◽  
The Central Nervous System ◽  
The Brain

Neurotrophins have been intensively studied and have multiple roles in the brain. Neurotrophins are first synthetized as proneurotrophins and then cleaved intracellularly and extracellularly. Increasing evidences demonstrate that proneurotrophins and mature neurotrophins exerts opposing role in the central nervous system. In the present review, we explore the role of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT3), and neurotrophin 4 (NT4) and their respective proform in cellular processes related to learning and memory. We focused on their roles in synaptic activity and plasticity in the brain with an emphasis on long-term potentiation, long-term depression, and basal synaptic transmission in the hippocampus and the temporal lobe area. We also discuss new findings on the role of the Val66Met polymorphism on the BDNF propeptide on synaptic activity.

Distance-Dependent Ni2+-Sensitivity of Synaptic Plasticity in Apical Dendrites of Hippocampal CA1 Pyramidal Cells

2002 ◽  
Vol 87 (2) ◽  
pp. 1169-1174 ◽  
Author(s):  
Yoshikazu Isomura ◽  
Yoko Fujiwara-Tsukamoto ◽  
Michiko Imanishi ◽  
Atsushi Nambu ◽  
Masahiko Takada
Keyword(s):  
Calcium Influx ◽  
Critical Role ◽  
Field Potential ◽  
Pyramidal Cells ◽  
Long Term Potentiation ◽  
Apical Dendrite ◽  
Excitatory Postsynaptic Potential ◽  
Distal Dendrite ◽  
Ca1 Pyramidal Cells ◽  
Hippocampal Ca1

Low concentration of Ni2+, a T- and R-type voltage-dependent calcium channel (VDCC) blocker, is known to inhibit the induction of long-term potentiation (LTP) in the hippocampal CA1 pyramidal cells. These VDCCs are distributed more abundantly at the distal area of the apical dendrite than at the proximal dendritic area or soma. Therefore we investigated the relationship between the Ni2+-sensitivity of LTP induction and the synaptic location along the apical dendrite. Field potential recordings revealed that 25 μM Ni2+ hardly influenced LTP at the proximal dendritic area (50 μm distant from the somata). In contrast, the same concentration of Ni2+ inhibited the LTP induction mildly at the middle dendritic area (150 μm) and strongly at the distal dendritic area (250 μm). Ni2+ did not significantly affect either the synaptic transmission at the distal dendrite or the burst-firing ability at the soma. However, synaptically evoked population spikes recorded near the somata were slightly reduced by Ni2+ application, probably owing to occlusion of dendritic excitatory postsynaptic potential (EPSP) amplification. Even when the stimulating intensity was strengthened sufficiently to overcome such a reduction in spike generation during LTP induction, the magnitude of distal LTP was not significantly recovered from the Ni2+-dependent inhibition. These results suggest that Ni2+ may inhibit the induction of distal LTP directly by blocking calcium influx through T- and/or R-type VDCCs. The differentially distributed calcium channels may play a critical role in the induction of LTP at dendritic synapses of the hippocampal pyramidal cells.

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