scholarly journals Dissociated Hippocampal Neurons Exhibit Distinct Zn2+ Dynamics in a Stimulation-Method-Dependent Manner

2020 ◽  
Vol 11 (4) ◽  
pp. 508-514 ◽  
Author(s):  
Lynn Sanford ◽  
Amy E. Palmer
Keyword(s):  
Hippocampal Neurons ◽  
Dependent Manner ◽  
Stimulation Method

scholarly journals Dissociated hippocampal neurons exhibit distinct Zn2+ dynamics in a stimulation method-dependent manner

2020 ◽  
Author(s):  
Lynn Sanford ◽  
Amy E. Palmer
Keyword(s):  
Hippocampal Neurons ◽  
Dependent Manner ◽  
Ph Change ◽  
Glutamatergic Neuron ◽  
Neuronal Excitation ◽  
Cellular Change ◽  
Bath Application ◽  
Intracellular Ca ◽  
Stimulation Method

ABSTRACTIonic Zn2+ has increasingly been recognized as an important neurotransmitter and signaling ion in glutamatergic neuron pathways. Intracellular Zn2+ transiently increases as a result of neuronal excitation, and this Zn2+ signal is essential for neuron plasticity, but the source and regulation of the signal is still unclear. In this study we rigorously quantified Zn2+, Ca2+ and pH dynamics in dissociated mouse hippocampal neurons stimulated with bath application of high KCl or glutamate. While both stimulation methods yielded Zn2+ signals, Ca2+ influx, and acidification, glutamate stimulation induced more sustained high intracellular Ca2+ and a larger increase in intracellular Zn2+. However, the stimulation-induced pH change was similar between conditions, indicating that a different cellular change is responsible for the stimulation-dependent difference in Zn2+ signal. This work provides the first robust quantification of Zn2+ dynamics in neurons using different methods of stimulation.

scholarly journals Live Cell FRET Imaging Reveals Amyloid β-Peptide Oligomerization in Hippocampal Neurons

2021 ◽  
Author(s):  
Yang Gao ◽  
Stefan Wennmalm ◽  
Bengt Winblad ◽  
Sophia Schedin-Weiss ◽  
Lars Tjernberg
Keyword(s):  
Hippocampal Neurons ◽  
Resonance Energy Transfer ◽  
Amyloid Β ◽  
Resonance Energy ◽  
Live Cell ◽  
Amyloid Β Peptide ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Late Endosomes ◽  
Aβ Oligomerization

Amyloid β-peptide (Aβ) oligomerization is believed to contribute to the neuronal dysfunction in Alzheimer disease (AD). Despite decades of research, many details of Aβ oligomerization in neurons still need to be revealed. Förster Resonance Energy Transfer (FRET) is a simple but effective way to study molecular interactions. Here we use a confocal microscope with a sensitive Airyscan detector for FRET detection. By live cell FRET imaging, we detect Aβ42 oligomerization in primary neurons. The neurons were incubated with fluorescently labelled Aβ42 in the cell culture medium for 24 hours. Aβ42 were internalized and oligomerized into the lysosomes/late endosomes in a concentration-dependent manner. Both the cellular uptake and intracellular oligomerization of Aβ42 were significantly higher than for Aβ40. These findings provide a better understanding of Aβ42 oligomerization in neurons.

scholarly journals δ-Catenin/NPRAP (neural plakophilin-related armadillo repeat protein) interacts with and activates sphingosine kinase 1

2004 ◽  
Vol 382 (2) ◽  
pp. 717-723 ◽  
Author(s):  
Toshitada FUJITA ◽  
Taro OKADA ◽  
Shun HAYASHI ◽  
Saleem JAHANGEER ◽  
Noriko MIWA ◽  
...  
Keyword(s):  
Cell Motility ◽  
Hippocampal Neurons ◽  
Mdck Cells ◽  
Specific Inhibitor ◽  
Sphingosine Kinase ◽  
Dependent Manner ◽  
Repeat Protein ◽  
Sphingosine 1 Phosphate ◽  
Key Enzyme ◽  
Armadillo Repeat

Sphingosine kinase (SPHK) is a key enzyme catalysing the formation of sphingosine 1-phosphate (SPP), a lipid messenger that is implicated in the regulation of a wide variety of important cellular events acting through intracellular, as well as extracellular, mechanisms. However, the molecular mechanism of intracellular actions of SPP remains unclear. Here, we have identified δ-catenin/NPRAP (neural plakophilin-related armadillo repeat protein) as a potential binding partner for SPHK1 by yeast two-hybrid screening. From co-immunoprecipitation analyses, the C-terminal portion of δ-catenin/NPRAP containing the seventh to tenth armadillo repeats was found to be required for interaction with SPHK1. Endogenous δ-catenin/NPRAP was co-localized with endogenous SPHK1 and transfected δ-catenin/NPRAP was co-localized with transfected SPHK1 in dissociated rat hippocampal neurons. MDCK (Madin–Darby canine kidney) cells stably expressing δ-catenin/NPRAP contained elevated levels of intracellular SPP. In a purified system δ-catenin/NPRAP stimulated SPHK1 in a dose-dependent manner. Furthermore, δ-catenin/NPRAP-induced increased cell motility in MDCK cells was completely inhibited by dimethylsphingosine, a specific inhibitor of SPHK1. These results strongly suggest that at least some of δ-catenin/NPRAP functions, including increased cell motility, are mediated by an SPHK–SPP signalling pathway.

scholarly journals Mini-GAGR, an intranasally applied polysaccharide, activates the neuronal Nrf2-mediated antioxidant defense system

2018 ◽  
Vol 293 (47) ◽  
pp. 18242-18269 ◽  
Author(s):  
Kelsey Murphy ◽  
Killian Llewellyn ◽  
Samuel Wakser ◽  
Josef Pontasch ◽  
Natasha Samanich ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Antioxidant System ◽  
Cortical Neurons ◽  
Hippocampal Neurons ◽  
Nuclear Translocation ◽  
Growth Factor Receptor ◽  
Antioxidant Defense System ◽  
Related Factor ◽  
Dependent Manner ◽  
Amyloid Aβ

Oxidative stress triggers and exacerbates neurodegeneration in Alzheimer's disease (AD). Various antioxidants reduce oxidative stress, but these agents have little efficacy due to poor blood–brain barrier (BBB) permeability. Additionally, single-modal antioxidants are easily overwhelmed by global oxidative stress. Activating nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) and its downstream antioxidant system are considered very effective for reducing global oxidative stress. Thus far, only a few BBB-permeable agents activate the Nrf2-dependent antioxidant system. Here, we discovered a BBB-bypassing Nrf2-activating polysaccharide that may attenuate AD pathogenesis. Mini-GAGR, a 0.7-kDa cleavage product of low-acyl gellan gum, increased the levels and activities of Nrf2-dependent antioxidant enzymes, decreased reactive oxygen species (ROS) under oxidative stress in mouse cortical neurons, and robustly protected mitochondria from oxidative insults. Moreover, mini-GAGR increased the nuclear localization and transcriptional activity of Nrf2 similarly to known Nrf2 activators. Mechanistically, mini-GAGR increased the dissociation of Nrf2 from its inhibitor, Kelch-like ECH-associated protein 1 (Keap1), and induced phosphorylation and nuclear translocation of Nrf2 in a protein kinase C (PKC)- and fibroblast growth factor receptor (FGFR1)-dependent manner. Finally, 20-day intranasal treatment of 3xTg-AD mice with 100 nmol of mini-GAGR increased nuclear p-Nrf2 and growth-associated protein 43 (GAP43) levels in hippocampal neurons, reduced p-tau and β-amyloid (Aβ) peptide–stained neurons, and improved memory. The BBB-bypassing Nrf2-activating polysaccharide reported here may be effective in reducing oxidative stress and neurodegeneration in AD.

scholarly journals Resonance with subthreshold oscillatory drive organizes activity and optimizes learning in neural networks

2018 ◽  
Vol 115 (13) ◽  
pp. E3017-E3025 ◽  
Author(s):  
James P. Roach ◽  
Aleksandra Pidde ◽  
Eitan Katz ◽  
Jiaxing Wu ◽  
Nicolette Ognjanovski ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
External Input ◽  
Neuronal Firing ◽  
Network Activity ◽  
Dependent Manner ◽  
Information Encoding ◽  
Subthreshold Oscillations ◽  
Neuronal Network Model ◽  
And Performance

Network oscillations across and within brain areas are critical for learning and performance of memory tasks. While a large amount of work has focused on the generation of neural oscillations, their effect on neuronal populations’ spiking activity and information encoding is less known. Here, we use computational modeling to demonstrate that a shift in resonance responses can interact with oscillating input to ensure that networks of neurons properly encode new information represented in external inputs to the weights of recurrent synaptic connections. Using a neuronal network model, we find that due to an input current-dependent shift in their resonance response, individual neurons in a network will arrange their phases of firing to represent varying strengths of their respective inputs. As networks encode information, neurons fire more synchronously, and this effect limits the extent to which further “learning” (in the form of changes in synaptic strength) can occur. We also demonstrate that sequential patterns of neuronal firing can be accurately stored in the network; these sequences are later reproduced without external input (in the context of subthreshold oscillations) in both the forward and reverse directions (as has been observed following learning in vivo). To test whether a similar mechanism could act in vivo, we show that periodic stimulation of hippocampal neurons coordinates network activity and functional connectivity in a frequency-dependent manner. We conclude that resonance with subthreshold oscillations provides a plausible network-level mechanism to accurately encode and retrieve information without overstrengthening connections between neurons.

scholarly journals Protective Effects of Scolopendra Water Extract on Trimethyltin-Induced Hippocampal Neurodegeneration and Seizures in Mice

2019 ◽  
Vol 9 (12) ◽  
pp. 369
Author(s):  
Yun-Soo Seo ◽  
Mary Jasmin Ang ◽  
Byeong Cheol Moon ◽  
Hyo Seon Kim ◽  
Goya Choi ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Primary Cultures ◽  
Water Extract ◽  
Model Systems ◽  
Inflammatory Factor ◽  
Dependent Manner ◽  
Protective Effects ◽  
Cell Degeneration

Trimethyltin (TMT) is an organotin compound with potent neurotoxic action characterized by neuronal degeneration in the hippocampus. This study evaluated the protective effects of a Scolopendra water extract (SWE) against TMT intoxication in hippocampal neurons, using both in vitro and in vivo model systems. Specifically, we examined the actions of SWE on TMT- (5 mM) induced cytotoxicity in primary cultures of mouse hippocampal neurons (7 days in vitro) and the effects of SWE on hippocampal degeneration in adult TMT- (2.6 mg/kg, intraperitoneal) treated C57BL/6 mice. We found that SWE pretreatment (0–100 μg/mL) significantly reduced TMT-induced cytotoxicity in cultured hippocampal neurons in a dose-dependent manner, as determined by lactate dehydrogenase and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assays. Additionally, this study showed that perioral administration of SWE (5 mg/kg), from −6 to 0 days before TMT injection, significantly attenuated hippocampal cell degeneration and seizures in adult mice. Furthermore, quantitative analysis of Iba-1 (Allograft inflammatory factor 1)- and GFAP (Glial fibrillary acidic protein)-immunostained cells revealed a significant reduction in the levels of Iba-1- and GFAP-positive cell bodies in the dentate gyrus (DG) of mice treated with SWE prior to TMT injection. These data indicated that SWE pretreatment significantly protected the hippocampus against the massive activation of microglia and astrocytes elicited by TMT. In addition, our data showed that the SWE-induced reduction of immune cell activation was linked to a significant reduction in cell death and a significant improvement in TMT-induced seizure behavior. Thus, we conclude that SWE ameliorated the detrimental effects of TMT toxicity on hippocampal neurons, both in vivo and in vitro. Altogether, our findings hint at a promising pharmacotherapeutic use of SWE in hippocampal degeneration and dysfunction.

TXA2 agonists inhibit high-voltage-activated calcium channels in rat hippocampal CA1 neurons

1996 ◽  
Vol 271 (4) ◽  
pp. C1269-C1277 ◽  
Author(s):  
K. S. Hsu ◽  
C. C. Huang ◽  
W. M. Kan ◽  
P. W. Gean
Keyword(s):  
Hippocampal Neurons ◽  
Cell Voltage ◽  
Specific Protein ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Whole Cell ◽  
Ca1 Neurons ◽  
Hippocampal Ca1 Neurons ◽  
Hippocampal Ca1 ◽  
Alpha 7

Whole cell voltage clamp recordings were used to investigate the effects of thromboxane A2 (TXA2) agonists on the voltage-dependent Ca2+ currents in rat hippocampal CA1 neurons. TXA2 agonists [1S-[1 alpha, 2 beta(5Z), 3 alpha(1E, 3S*)4 alpha ]]-7-[3-[3-hydroxy-4-(4'-iodophenoxy)-1-butenyl]-7-oxabicyclo [2,2,1]heptan-2-yl]-5-heptenoic acid (I-BOP) and U-46619, reversibly suppressed the whole cell Ca2+ currents in a concentration-dependent manner. The effect was blocked by specific TXA2 receptor antagonist, SQ-29548. I-BOP as well as U-46619 inhibited both omega-conotoxin GVIA (CgTx)-sensitive and nimodipine sensitive Ca2+ currents but had no effect on CgTx/nimodipine insensitive Ca2+ currents. The I-BOP and U-46619 inhibition of Ca2+ currents was blocked by internal dialysis of hippocampal neurons with specific protein kinase C (PKC) inhibitors, NPC-15437 and PKC inhibitor-(19-36). Pretreatment of hippocampal neurons with either 5 micrograms/ml pertussis toxin (PTX) or 5 micrograms/ml cholera toxin (CTX) did not significantly affect the suppression of the Ca2+ currents by I-BOP and U-46619. Dialyzing with 1 mM guanosine 5'-O-(3-thiotriphosphate) or 1 mM GDP significantly attenuated the I-BOP or U-46619 action. These results demonstrate that TXA2 agonists inhibit both CgTx- and nimodipine-sensitive Ca2+ currents but not CgTx/nimodipine-insensitive currents in rat hippocampal CA1 neurons via a PTX- and CTX-insensitive G protein-coupled activation of the PKC pathway.

Benzodiazepines Block α2-Containing Inhibitory Glycine Receptors in Embryonic Mouse Hippocampal Neurons

2003 ◽  
Vol 90 (1) ◽  
pp. 89-99 ◽  
Author(s):  
Liu Lin Thio ◽  
Ananth Shanmugam ◽  
Keith Isenberg ◽  
Kelvin Yamada
Keyword(s):  
Hippocampal Neurons ◽  
Clinical Effects ◽  
Dependent Manner ◽  
Glycine Receptors ◽  
Binding Studies ◽  
Chloride Currents ◽  
Embryonic Mouse ◽  
Voltage Dependent ◽  
Polymerase Chain ◽  
Dose Dependent

Inhibitory glycine receptors (GlyRs) in the mammalian cortex probably contribute to brain development and to maintaining tonic inhibition. Given their presence throughout the cortex, their modulation likely has important physiological consequences. Although benzodiazepines potentiate γ-aminobutyric acidA receptors (GABAARs), they may also modulate GlyRs because binding studies initially suggested that they act at GlyRs. Furthermore, their diminished ability to potentiate neonatal GABAARs suggests that they may exert their beneficial clinical effects at another site in the developing brain. Therefore we examined the effect of benzodiazepines on whole cell currents mediated by GlyRs in cultured embryonic mouse hippocampal neurons. First, we determined the GlyR subunit composition in this preparation. Glycine, β-alanine, and taurine activate strychnine-sensitive chloride currents in a dose-dependent manner. Maximal concentrations of the three agonists produce equal, nonadditive responses as expected of full agonists. The pharmacological properties of the GlyR currents including their pattern of modulation by picrotoxinin, picrotin, and tropisetron indicate that GlyRs consist of α2β heteromers and α2 homomers. Reverse transcriptase polymerase chain reaction (RTPCR) studies confirmed the presence of α2 and β subunits. Second, we found that micromolar concentrations of some benzodiazepines, including chlordiazepoxide and nitrazepam, inhibit GlyR currents. Nitrazepam inhibition of GlyRs is noncompetitive, is not voltage dependent, and does not reflect enhanced desensitization. Thus benzodiazepines allosterically inhibit α2-containing GlyRs in embryonic mouse hippocampal neurons via a “low”-affinity site.

scholarly journals CRMP-2 Is Involved in Kinesin-1-Dependent Transport of the Sra-1/WAVE1 Complex and Axon Formation

2005 ◽  
Vol 25 (22) ◽  
pp. 9920-9935 ◽  
Author(s):  
Yoji Kawano ◽  
Takeshi Yoshimura ◽  
Daisuke Tsuboi ◽  
Saeko Kawabata ◽  
Takako Kaneko-Kawano ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Hippocampal Neurons ◽  
Binding Proteins ◽  
Neuronal Development ◽  
Critical Role ◽  
Growth Cones ◽  
Axon Outgrowth ◽  
Actin Binding ◽  
Dependent Manner ◽  
Actin Binding Proteins

ABSTRACT A neuron has two types of highly polarized cell processes, the single axon and multiple dendrites. One of the fundamental questions of neurobiology is how neurons acquire such specific and polarized morphologies. During neuronal development, various actin-binding proteins regulate dynamics of actin cytoskeleton in the growth cones of developing axons. The regulation of actin cytoskeleton in the growth cones is thought to be involved in axon outgrowth and axon-dendrite specification. However, it is largely unknown which actin-binding proteins are involved in axon-dendrite specification and how they are transported into the developing axons. We have previously reported that collapsin response mediator protein 2 (CRMP-2) plays a critical role in axon outgrowth and axon-dendrite specification (N. Inagaki, K. Chihara, N. Arimura, C. Menager, Y. Kawano, N. Matsuo, T. Nishimura, M. Amano, and K. Kaibuchi, Nat. Neurosci. 4:781-782, 2001). Here, we found that CRMP-2 interacted with the specifically Rac1-associated protein 1 (Sra-1)/WASP family verprolin-homologous protein 1 (WAVE1) complex, which is a regulator of actin cytoskeleton. The knockdown of Sra-1 and WAVE1 by RNA interference canceled CRMP-2-induced axon outgrowth and multiple-axon formation in cultured hippocampal neurons. We also found that CRMP-2 interacted with the light chain of kinesin-1 and linked kinesin-1 to the Sra-1/WAVE1 complex. The knockdown of CRMP-2 and kinesin-1 delocalized Sra-1 and WAVE1 from the growth cones of axons. These results suggest that CRMP-2 transports the Sra-1/WAVE1 complex to axons in a kinesin-1-dependent manner and thereby regulates axon outgrowth and formation.

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