scholarly journals Light Stimulation Parameters Determine Neuron Dynamic Characteristics

2019 ◽  
Vol 9 (18) ◽  
pp. 3673 ◽  
Author(s):  
Alexander Erofeev ◽  
Evgenii Gerasimov ◽  
Anastasia Lavrova ◽  
Anastasia Bolshakova ◽  
Eugene Postnikov ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Light Pulse ◽  
Hippocampal Neurons ◽  
Primary Cultures ◽  
Optimal Parameters ◽  
Neuronal Function ◽  
Light Stimulation ◽  
Stimulation Parameters ◽  
Transgenic Lines ◽  
Bell Shaped Curve

Optogenetics is a recently developed technique that is widely used to study neuronal function. In optogenetic experiments, neurons encode opsins (channelrhodopsins, halorhodopsins or their derivatives) by means of viruses, plasmids or genetic modification (transgenic lines). Channelrhodopsin are light activated ion channels. Their expression in neurons allows light-dependent control of neuronal activity. The duration and frequency of light stimulation in optogenetic experiments is critical for stable, robust and reproducible experiments. In this study, we performed systematic analyses of these parameters using primary cultures of hippocampal neurons transfected with channelrhodopsin-2 (ChR2). The main goal of this work was to identify the optimal parameters of light stimulation that would result in stable neuronal activity during a repeated light pulse train. We demonstrated that the dependency of the photocurrent on the light pulse duration is described by a right-skewed bell-shaped curve, while the dependence on the stimulus intensity is close to linear. We established that a duration between 10–30 ms of stimulation was the minimal time necessary to achieve a full response. Obtained results will be useful in planning and interpretation of optogenetic experiments.

scholarly journals Activity-dependent nucleation of dynamic microtubules at presynaptic boutons is required for neurotransmission

2019 ◽  
Author(s):  
Xiaoyi Qu ◽  
Atul Kumar ◽  
Heike Blockus ◽  
Clarissa Waites ◽  
Francesca Bartolini
Keyword(s):  
Synaptic Vesicle ◽  
Neuronal Activity ◽  
Neurotransmitter Release ◽  
Hippocampal Neurons ◽  
De Novo ◽  
List Type ◽  
Neuronal Function ◽  
Presynaptic Boutons ◽  
Rate Limiting ◽  
Activity Dependent

SUMMARYControl of microtubule (MT) dynamics is critical for neuronal function. Whether MT nucleation is regulated at presynaptic boutons and influences overall presynaptic activity remains unknown. By visualizing MT dynamics at individual excitatory en passant boutons in axons of hippocampal neurons we found that MTs preferentially grow from presynaptic boutons as a result of γ-tubulin and augmin-dependent nucleation. MT nucleation at boutons is promoted by neuronal activity, functionally coupled to synaptic vesicle (SV) transport, and required for neurotransmission. Hence, en passant boutons act as hotspots for activity-dependent MT nucleation, which is required for neurotransmission by providing the tracks for a rate-limiting supply of SVs to sites of neurotransmitter release.HighlightsExcitatory boutons are hotspots for neuronal activity-induced γ-tubulin dependent MT nucleationThe augmin complex is required for the correct polarity of presynaptic de novo nucleated MTsPresynaptic MT nucleation promotes SV motility and exocytosis at sites of releaseIn BriefOur results demonstrate that excitatory en passant boutons are hotspots for neuronal activity-induced γ-tubulin- and augmin-dependent oriented MT nucleation, and that the resulting presynaptic de novo nucleated MTs promote inter-bouton SV motility which is rate-limiting for neurotransmitter release.

scholarly journals Neuronal receptors display cytoskeleton-independent directed motion on the plasma membrane

2018 ◽  
Author(s):  
R. D. Taylor ◽  
M. Heine ◽  
N. J. Emptage ◽  
L. C. Andreae
Keyword(s):  
Plasma Membrane ◽  
Neuronal Activity ◽  
Particle Tracking ◽  
Hippocampal Neurons ◽  
Intracellular Transport ◽  
Transmembrane Proteins ◽  
Single Particle Tracking ◽  
Directed Motion ◽  
Surface Movement ◽  
Transport Vesicles

AbstractDirected transport of transmembrane proteins is generally believed to occur via intracellular transport vesicles. However, using single particle tracking in rat hippocampal neurons with a pH-sensitive quantum dot probe which specifically reports surface movement of receptors, we have identified a subpopulation of neuronal EphB2 receptors that exhibit directed motion between synapses within the plasma membrane itself. This receptor movement occurs independently of the cytoskeleton but is dependent on cholesterol and is regulated by neuronal activity.

scholarly journals The Impact of Oxytocin on Neurite Outgrowth and Synaptic Proteins in Magel2-Deficient Mice

2020 ◽  
Author(s):  
Alexandra Reichova ◽  
Fabienne Schaller ◽  
Stanislava Bukatova ◽  
Zuzana Bacova ◽  
Françoise Muscatelli ◽  
...  
Keyword(s):  
Neurite Outgrowth ◽  
Hippocampal Neurons ◽  
Synapse Formation ◽  
Primary Cultures ◽  
Synaptic Proteins ◽  
Neuronal Maturation ◽  
Glutamatergic Synapses ◽  
Associated Proteins ◽  
The Impact ◽  
Deficient Mice

AbstractOxytocin contributes to the regulation of cytoskeletal and synaptic proteins and could therefore affect the mechanisms of neurodevelopmental disorders, including autism. Both the Prader-Willi syndrome and Schaaf-Yang syndrome exhibit autistic symptoms involving the MAGEL2 gene. Magel2-deficient mice show a deficit in social behavior that is rescued following postnatal administration of oxytocin. Here, in Magel2-deficient mice, we showed that the neurite outgrowth of primary cultures of immature hippocampal neurons is reduced. Treatment with oxytocin, but not retinoic acid, reversed this abnormality. In the hippocampus of Magel2-deficient pups, we further demonstrated that several transcripts of neurite outgrowth-associated proteins, synaptic vesicle proteins, and cell-adhesion molecules are decreased. In the juvenile stage, when neurons are mature, normalization or even overexpression of most of these markers was observed, suggesting a delay in the neuronal maturation of Magel2-deficient pups. Moreover, we found reduced transcripts of the excitatory postsynaptic marker, Psd95 in the hippocampus and we observed a decrease of PSD95/VGLUT2 colocalization in the hippocampal CA1 and CA3 regions in Magel2-deficient mice, indicating a defect in glutamatergic synapses. Postnatal administration of oxytocin upregulated postsynaptic transcripts in pups; however, it did not restore the level of markers of glutamatergic synapses in Magel2-deficient mice. Overall, Magel2 deficiency leads to abnormal neurite outgrowth and reduced glutamatergic synapses during development, suggesting abnormal neuronal maturation. Oxytocin stimulates the expression of numerous genes involved in neurite outgrowth and synapse formation in early development stages. Postnatal oxytocin administration has a strong effect in development that should be considered for certain neuropsychiatric conditions in infancy.

The effect and optimal parameters of repetitive transcranial magnetic stimulation on motor recovery in stroke patients: a systematic review and meta-analysis of randomized controlled trials

2019 ◽  
Vol 33 (5) ◽  
pp. 847-864 ◽  
Author(s):  
Huifang Xiang ◽  
Jing Sun ◽  
Xiang Tang ◽  
Kebin Zeng ◽  
Xiushu Wu
Keyword(s):  
Motor Function ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Meta Analysis ◽  
Motor Recovery ◽  
Controlled Trials ◽  
Optimal Parameters ◽  
Stroke Patients ◽  
Randomized Controlled ◽  
Stimulation Parameters ◽  
Stroke Population

Objective: The primary aim of this meta-analysis was to evaluate the effects of repetitive transcranial magnetic stimulation (rTMS) on limb movement recovery post-stroke and cortex excitability, to explore the optimal parameters of rTMS and suitable stroke population. Second, adverse events were also included. Data sources: The databases of PubMed, EBSCO, MEDLINE, the Cochrane Central Register of Controlled Trials, EBM Reviews-Cochrane Database, the Chinese National Knowledge Infrastructure, and the Chinese Science and Technology Journals Database were searched for randomized controlled trials exploring the effects of rTMS on limb motor function recovery post-stroke before December 2018. Review methods: The effect sizes of rTMS on limb motor recovery, the effect size of rTMS stimulation parameters, and different stroke population were summarized by calculating the standardized mean difference (SMD) and the 95% confidence interval using fixed/random effect models as appropriate. Results: For the motor function assessment, 42 eligible studies involving 1168 stroke patients were identified. The summary effect size indicated that rTMS had positive effects on limb motor recovery (SMD = 0.50, P < 0.00001) and activities of daily living (SMD = 0.82, P < 0.00001), and motor-evoked potentials of the stimulated hemisphere differed according to the stimulation frequency, that is, the high-frequency group (SMD = 0.57, P = 0.0006), except the low-frequency group (SMD = –0.27, P = 0.05). No significant differences were observed among the stimulation parameter subgroups except for the sessions subgroup ( P = 0.02). Only 10 included articles reported transient mild discomfort after rTMS. Conclusions: rTMS promoted the recovery of limb motor function and changed the cortex excitability. rTMS may be better for early and pure subcortical stroke patients. Regarding different stimulation parameters, the number of stimulation sessions has an impact on the effect of rTMS.

scholarly journals Neuroprotective Effects of Grape Seed Procyanidins on Ethanol-Induced Injury and Oxidative Stress in Rat Hippocampal Neurons

2020 ◽  
Vol 55 (4) ◽  
pp. 357-366
Author(s):  
Wenyang Jin ◽  
Mizhu Sun ◽  
Bingbing Yuan ◽  
Runzhi Wang ◽  
Hongtao Yan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hippocampal Neurons ◽  
Primary Cultures ◽  
Neuronal Injury ◽  
Grape Seed ◽  
Neuroprotective Effects ◽  
Dendritic Length ◽  
New Type ◽  
The Brain ◽  
And Oxidative Stress

Abstract Aims Ethanol is a small molecule capable of interacting with numerous targets in the brain, the mechanisms of which are complex and still poorly understood. Studies have revealed that ethanol-induced hippocampal neuronal injury is associated with oxidative stress. Grape seed procyanidin (GSP) is a new type of antioxidant that is believed to scavenge free radicals and be anti-inflammatory. This study evaluated the ability and mechanism by which the GSP improves ethanol-induced hippocampal neuronal injury. Methods Primary cultures of hippocampal neurons were exposed to ethanol (11, 33 and 66 mM, 1, 4, 8, 12 and 24 h) and the neuroprotective effects of GSP were assessed by evaluating the activity of superoxide dismutase (SOD), the levels of malondialdehyde (MDA) and lactate dehydrogenase (LDH) and cell morphology. Results Our results indicated that GSP prevented ethanol-induced neuronal injury by reducing the levels of MDA and LDH, while increasing the activity of SOD. In addition, GSP increased the number of primary dendrites and total dendritic length per cell. Conclusion Together with previous findings, these results lend further support to the significance of developing GSP as a therapeutic tool for use in the treatment of alcohol use disorders.

scholarly journals Macrophage Migration Inhibitory Factor Alters Functional Properties of CA1 Hippocampal Neurons in Mouse Brain Slices

2019 ◽  
Vol 21 (1) ◽  
pp. 276 ◽  
Author(s):  
Eric Bancroft ◽  
Rahul Srinivasan ◽  
Lee A. Shapiro
Keyword(s):  
Ischemic Stroke ◽  
Mouse Brain ◽  
Migration Inhibitory Factor ◽  
Hippocampal Neurons ◽  
Macrophage Migration Inhibitory Factor ◽  
Hippocampal Slices ◽  
Inhibitory Factor ◽  
Macrophage Migration ◽  
Cns Injury ◽  
Neuronal Function

Neuroinflammation is implicated in a host of neurological insults, such as traumatic brain injury (TBI), ischemic stroke, Alzheimer’s disease, Parkinson’s disease, and epilepsy. The immune response to central nervous system (CNS) injury involves sequelae including the release of numerous cytokines and chemokines. Macrophage migration inhibitory factor (MIF), is one such cytokine that is elevated following CNS injury, and is associated with the prognosis of TBI, and ischemic stroke. MIF has been identified in astrocytes and neurons, and some of the trophic actions of MIF have been related to its direct and indirect actions on astrocytes. However, the potential modulation of CNS neuronal function by MIF has not yet been explored. This study tests the hypothesis that MIF can directly influence hippocampal neuronal function. MIF was microinjected into the hippocampus and the genetically encoded calcium indicator, GCaMP6f, was used to measure Ca2+ events in acute adult mouse brain hippocampal slices. Results demonstrated that a single injection of 200 ng MIF into the hippocampus significantly increased baseline calcium signals in CA1 pyramidal neuron somata, and altered calcium responses to N-methyl-d-aspartate (NMDA) + D-serine in pyramidal cell apical dendrites located in the stratum radiatum. These data are the first to show direct effects of MIF on hippocampal neurons and on NMDA receptor function. Considering that MIF is elevated after brain insults such as TBI, the data suggest that, in addition to the previously described role of MIF in astrocyte reactivity, elevated MIF can have significant effects on neuronal function in the hippocampus.

Association of electroanalytical and spectrophotometric methods to evaluate the antioxidant activity of isobenzofuranone in primary cultures of hippocampal neurons

2020 ◽  
Vol 68 ◽  
pp. 104970
Author(s):  
Aniely dos Reis Teixeira ◽  
Róbson Ricardo Teixeira ◽  
Iara Mariana Lellis Ribeiro ◽  
Wagner Luiz Pereira ◽  
Taise Matte Manhabosco ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Hippocampal Neurons ◽  
Primary Cultures ◽  
Spectrophotometric Methods
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