The role of Npas4 in neurite outgrowth and phosphorylated synapsin I expression in Neuro2a cells and primary cultured hippocampal neurons

2010 ◽  
Vol 68 ◽  
pp. e251
Author(s):  
Jaesuk Yun ◽  
Taku Nagai ◽  
Yoko Hibi ◽  
Hiroyuki Koike ◽  
Atumi Nitta ◽  
...  
Keyword(s):  
Neurite Outgrowth ◽  
Hippocampal Neurons ◽  
Synapsin I ◽  
Neuro2a Cells ◽  
Cultured Hippocampal Neurons

scholarly journals 1,800 MHz Radiofrequency Electromagnetic Irradiation Impairs Neurite Outgrowth With a Decrease in Rap1-GTP in Primary Mouse Hippocampal Neurons and Neuro2a Cells

2021 ◽  
Vol 9 ◽  
Author(s):  
Yanqi Li ◽  
Ping Deng ◽  
Chunhai Chen ◽  
Qinlong Ma ◽  
Huifeng Pi ◽  
...  
Keyword(s):  
Protein Expression ◽  
Cell Viability ◽  
Brain Development ◽  
Neurite Outgrowth ◽  
Hippocampal Neurons ◽  
Neurite Length ◽  
Primary Mouse ◽  
Primary Hippocampal Neurons ◽  
Neuro2a Cells

Background: With the global popularity of communication devices such as mobile phones, there are increasing concerns regarding the effect of radiofrequency electromagnetic radiation (RF-EMR) on the brain, one of the most important organs sensitive to RF-EMR exposure at 1,800 MHz. However, the effects of RF-EMR exposure on neuronal cells are unclear. Neurite outgrowth plays a critical role in brain development, therefore, determining the effects of 1,800 MHz RF-EMR exposure on neurite outgrowth is important for exploring its effects on brain development.Objectives: We aimed to investigate the effects of 1,800 MHz RF-EMR exposure for 48 h on neurite outgrowth in neuronal cells and to explore the associated role of the Rap1 signaling pathway.Material and Methods: Primary hippocampal neurons from C57BL/6 mice and Neuro2a cells were exposed to 1,800 MHz RF-EMR at a specific absorption rate (SAR) value of 4 W/kg for 48 h. CCK-8 assays were used to determine the cell viability after 24, 48, and 72 h of irradiation. Neurite outgrowth of primary hippocampal neurons (DIV 2) and Neuro2a cells was observed with a 20 × optical microscope and recognized by ImageJ software. Rap1a and Rap1b gene expressions were detected by real-time quantitative PCR. Rap1, Rap1a, Rap1b, Rap1GAP, and p-MEK1/2 protein expressions were detected by western blot. Rap1-GTP expression was detected by immunoprecipitation. The role of Rap1-GTP was assessed by transfecting a constitutively active mutant plasmid (Rap1-Gly_Val-GFP) into Neuro2a cells.Results: Exposure to 1,800 MHz RF-EMR for 24, 48, and 72 h at 4 W/kg did not influence cell viability. The neurite length, primary and secondary neurite numbers, and branch points of primary mouse hippocampal neurons were significantly impaired by 48-h RF-EMR exposure. The neurite-bearing cell percentage and neurite length of Neuro2a cells were also inhibited by 48-h RF-EMR exposure. Rap1 activity was inhibited by 48-h RF-EMR with no detectable alteration in either gene or protein expression of Rap1. The protein expression of Rap1GAP increased after 48-h RF-EMR exposure, while the expression of p-MEK1/2 protein decreased. Overexpression of constitutively active Rap1 reversed the decrease in Rap1-GTP and the neurite outgrowth impairment in Neuro2a cells induced by 1,800 MHz RF-EMR exposure for 48 h.Conclusion: Rap1 activity and related signaling pathways are involved in the disturbance of neurite outgrowth induced by 48-h 1,800 MHz RF-EMR exposure. The effects of RF-EMR exposure on neuronal development in infants and children deserve greater focus.

scholarly journals Suppression of kinesin expression in cultured hippocampal neurons using antisense oligonucleotides.

1992 ◽  
Vol 117 (3) ◽  
pp. 595-606 ◽  
Author(s):  
A Ferreira ◽  
J Niclas ◽  
R D Vale ◽  
G Banker ◽  
K S Kosik
Keyword(s):  
Neurite Outgrowth ◽  
Cell Body ◽  
Heavy Chain ◽  
Antisense Oligonucleotides ◽  
Hippocampal Neurons ◽  
Full Recovery ◽  
Synapsin I ◽  
Neurite Length ◽  
Protein Levels ◽  
Cultured Hippocampal Neurons

Kinesin, a microtubule-based force-generating molecule, is thought to translocate organelles along microtubules. To examine the function of kinesin in neurons, we sought to suppress kinesin heavy chain (KHC) expression in cultured hippocampal neurons using antisense oligonucleotides and study the phenotype of these KHC "null" cells. Two different antisense oligonucleotides complementary to the KHC sequence reduced the protein levels of the heavy chain by greater than 95% within 24 h after application and produced identical phenotypes. After inhibition of KHC expression for 24 or 48 h, neurons extended an array of neurites often with one neurite longer than the others; however, the length of all these neurites was significantly reduced. Inhibition of KHC expression also altered the distribution of GAP-43 and synapsin I, two proteins thought to be transported in association with membranous organelles. These proteins, which are normally localized at the tips of growing neurites, were confined to the cell body in antisense-treated cells. Treatment of the cells with the corresponding sense oligonucleotides affected neither the distribution of GAP-43 and synapsin I, nor the length of neurites. A full recovery of neurite length occurred after removal of the antisense oligonucleotides from the medium. These data indicate that KHC plays a role in the anterograde translocation of vesicles containing GAP-43 and synapsin I. A deficiency in vesicle delivery may also explain the inhibition of neurite outgrowth. Despite the inhibition of KHC and the failure of GAP-43 and synapsin I to move out of the cell body, hippocampal neurons can extend processes and acquire as asymmetric morphology.

Role of GluN2A and GluN2B subunits in the formation of filopodia and secondary dendrites in cultured hippocampal neurons

2011 ◽  
Vol 385 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Frank Henle ◽  
Martina Dehmel ◽  
Jost Leemhuis ◽  
Catharina Fischer ◽  
Dieter K. Meyer
Keyword(s):  
Hippocampal Neurons ◽  
Cultured Hippocampal Neurons

Role of Presynaptic L-Type Ca2+ Channels in GABAergic Synaptic Transmission in Cultured Hippocampal Neurons

1999 ◽  
Vol 81 (3) ◽  
pp. 1225-1230 ◽  
Author(s):  
Kimmo Jensen ◽  
Morten Skovgaard Jensen ◽  
John D. C. Lambert
Keyword(s):  
Synaptic Transmission ◽  
Transmitter Release ◽  
Hippocampal Neurons ◽  
Low Frequency ◽  
Tetanic Stimulation ◽  
Vesicle Release ◽  
Gabaergic Synaptic Transmission ◽  
Cultured Hippocampal Neurons ◽  
40 Hz

Role of presynaptic L-type Ca2+ channels in GABAergic synaptic transmission in cultured hippocampal neurons. Using dual whole cell patch-clamp recordings of monosynaptic GABAergic inhibitory postsynaptic currents (IPSCs) in cultured rat hippocampal neurons, we have previously demonstrated posttetanic potentiation (PTP) of IPSCs. Tetanic stimulation of the GABAergic neuron leads to accumulation of Ca2+ in the presynaptic terminals. This enhances the probability of GABA-vesicle release for up to 1 min, which underlies PTP. In the present study, we have examined the effect of altering the probability of release on PTP of IPSCs. Baclofen (10 μM), which depresses presynaptic Ca2+ entry through N- and P/Q-type voltage-dependent Ca2+ channels (VDCCs), caused a threefold greater enhancement of PTP than did reducing [Ca2+]o to 1.2 mM, which causes a nonspecific reduction in Ca2+ entry. This finding prompted us to investigate whether presynaptic L-type VDCCs contribute to the Ca2+ accumulation in the boutons during spike activity. The L-type VDCC antagonist, nifedipine (10 μM), had no effect on single IPSCs evoked at 0.2 Hz but reduced the PTP evoked by a train of 40 Hz for 2 s by 60%. Another L-type VDCC antagonist, isradipine (5 μM), similarly inhibited PTP by 65%. Both L-type VDCC blockers also depressed IPSCs during the stimulation (i.e., they increased tetanic depression). The L-type VDCC “agonist” (−)BayK 8644 (4 μM) had no effect on PTP evoked by a train of 40 Hz for 2 s, which probably saturated the PTP process, but enhanced PTP evoked by a train of 1 s by 91%. In conclusion, the results indicate that L-type VDCCs do not participate in low-frequency synchronous transmitter release, but contribute to presynaptic Ca2+ accumulation during high-frequency activity. This helps maintain vesicle release during tetanic stimulation and also enhances the probability of transmitter release during the posttetanic period, which is manifest as PTP. Involvement of L-type channels in these processes represents a novel presynaptic regulatory mechanism at fast CNS synapses.

scholarly journals Differential neurite outgrowth is required for axon specification by cultured hippocampal neurons

2012 ◽  
Vol 123 (6) ◽  
pp. 904-910 ◽  
Author(s):  
Hideaki Yamamoto ◽  
Takanori Demura ◽  
Mayu Morita ◽  
Gary A. Banker ◽  
Takashi Tanii ◽  
...  
Keyword(s):  
Neurite Outgrowth ◽  
Hippocampal Neurons ◽  
Axon Specification ◽  
Cultured Hippocampal Neurons

scholarly journals L-type Ca2+ channel–mediated Ca2+ influx adjusts neuronal mitochondrial function to physiological and pathophysiological conditions

2020 ◽  
Vol 13 (618) ◽  
pp. eaaw6923 ◽  
Author(s):  
Matej Hotka ◽  
Michal Cagalinec ◽  
Karlheinz Hilber ◽  
Livia Hool ◽  
Stefan Boehm ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Atp Synthase ◽  
Mitochondrial Function ◽  
Hippocampal Neurons ◽  
Mitochondrial Depolarization ◽  
Voltage Gated ◽  
Beneficial Effects ◽  
Reverse Mode ◽  
Cultured Hippocampal Neurons

L-type voltage-gated Ca2+ channels (LTCCs) are implicated in neurodegenerative processes and cell death. Accordingly, LTCC antagonists have been proposed to be neuroprotective, although this view is disputed, because intentional LTCC activation can also have beneficial effects. LTCC-mediated Ca2+ influx influences mitochondrial function, which plays a crucial role in the regulation of cell viability. Hence, we investigated the effect of modulating LTCC-mediated Ca2+ influx on mitochondrial function in cultured hippocampal neurons. To activate LTCCs, neuronal activity was stimulated by increasing extracellular K+ or by application of the GABAA receptor antagonist bicuculline. The activity of LTCCs was altered by application of an agonistic (Bay K8644) or an antagonistic (isradipine) dihydropyridine. Our results demonstrated that activation of LTCC-mediated Ca2+ influx affected mitochondrial function in a bimodal manner. At moderate stimulation strength, ATP synthase activity was enhanced, an effect that involved Ca2+-induced Ca2+ release from intracellular stores. In contrast, high LTCC-mediated Ca2+ loads led to a switch in ATP synthase activity to reverse-mode operation. This effect, which required nitric oxide, helped to prevent mitochondrial depolarization and sustained increases in mitochondrial Ca2+. Our findings indicate a complex role of LTCC-mediated Ca2+ influx in the tuning and maintenance of mitochondrial function. Therefore, the use of LTCC inhibitors to protect neurons from neurodegeneration should be reconsidered carefully.

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