Early NMDA Receptor Ablation in Interneurons Causes an Activity-Dependent E/I Imbalance in vivo in Prefrontal Cortex Pyramidal Neurons of a Mouse Model Useful for the Study of Schizophrenia

2021 ◽  
Author(s):  
Diego E Pafundo ◽  
Carlos A Pretell Annan ◽  
Nicolas M Fulginiti ◽  
Juan E Belforte
Keyword(s):  
Prefrontal Cortex ◽  
Mouse Model ◽  
Pyramidal Neurons ◽  
Gamma Oscillations ◽  
Dependent Manner ◽  
Early Postnatal Development ◽  
Synaptic Inputs ◽  
Selective Ablation ◽  
Activity Dependent

Abstract Altered Excitatory/Inhibitory (E/I) balance of cortical synaptic inputs has been proposed as a central pathophysiological factor for psychiatric neurodevelopmental disorders, including schizophrenia (SZ). However, direct measurement of E/I synaptic balance have not been assessed in vivo for any validated SZ animal model. Using a mouse model useful for the study of SZ we show that a selective ablation of NMDA receptors (NMDAr) in cortical and hippocampal interneurons during early postnatal development results in an E/I imbalance in vivo, with synaptic inputs to pyramidal neurons shifted towards excitation in the adult mutant medial prefrontal cortex (mPFC). Remarkably, this imbalance depends on the cortical state, only emerging when theta and gamma oscillations are predominant in the network. Additional brain slice recordings and subsequent 3D morphological reconstruction showed that E/I imbalance emerges after adolescence concomitantly with significant dendritic retraction and dendritic spine re-localization in pyramidal neurons. Therefore, early postnatal ablation of NMDAr in cortical and hippocampal interneurons developmentally impacts on E/I imbalance in vivo in an activity-dependent manner.

Extracellular Release of ILEI/FAM3C and Amyloid-β Is Associated with the Activation of Distinct Synapse Subpopulations

2021 ◽  
pp. 1-16
Author(s):  
Masaki Nakano ◽  
Yachiyo Mitsuishi ◽  
Lei Liu ◽  
Naoki Watanabe ◽  
Emi Hibino ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Epithelial Mesenchymal Transition ◽  
Surrogate Marker ◽  
Amyloid Β ◽  
Dependent Manner ◽  
Mesenchymal Transition ◽  
Extracellular Release ◽  
Activity Dependent ◽  
Aβ Production

Background: Brain amyloid-β (Aβ) peptide is released into the interstitial fluid (ISF) in a neuronal activity-dependent manner, and Aβ deposition in Alzheimer’s disease (AD) is linked to baseline neuronal activity. Although the intrinsic mechanism for Aβ generation remains to be elucidated, interleukin-like epithelial-mesenchymal transition inducer (ILEI) is a candidate for an endogenous Aβ suppressor. Objective: This study aimed to access the mechanism underlying ILEI secretion and its effect on Aβ production in the brain. Methods: ILEI and Aβ levels in the cerebral cortex were monitored using a newly developed ILEI-specific ELISA and in vivo microdialysis in mutant human Aβ precursor protein-knockin mice. ILEI levels in autopsied brains and cerebrospinal fluid (CSF) were measured using ELISA. Results: Extracellular release of ILEI and Aβ was dependent on neuronal activation and specifically on tetanus toxin-sensitive exocytosis of synaptic vesicles. However, simultaneous monitoring of extracellular ILEI and Aβ revealed that a spontaneous fluctuation of ILEI levels appeared to inversely mirror that of Aβ levels. Selective activation and inhibition of synaptic receptors differentially altered these levels. The evoked activation of AMPA-type receptors resulted in opposing changes to ILEI and Aβ levels. Brain ILEI levels were selectively decreased in AD. CSF ILEI concentration correlated with that of Aβ and were reduced in AD and mild cognitive impairment. Conclusion: ILEI and Aβ are released from distinct subpopulations of synaptic terminals in an activity-dependent manner, and ILEI negatively regulates Aβ production in specific synapse types. CSF ILEI might represent a surrogate marker for the accumulation of brain Aβ.

scholarly journals Murine monoclonal antibodies against RBD of SARS-CoV-2 neutralize authentic wild type SARS-CoV-2 as well as B.1.1.7 and B.1.351 viruses and protect in vivo in a mouse model in a neutralization dependent manner

2021 ◽  
Author(s):  
Fatima Amanat ◽  
Shirin Strohmeier ◽  
Wen-Hsin Lee ◽  
Sandhya Bangaru ◽  
Andrew B Ward ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Severe Acute Respiratory Syndrome ◽  
Mouse Model ◽  
Neutralizing Antibodies ◽  
Dependent Manner ◽  
Receptor Binding Domain ◽  
Wild Type ◽  
Murine Monoclonal Antibodies

After first emerging in December 2019 in China, severe acute respiratory syndrome 2 (SARS-CoV-2) has since caused a pandemic leading to millions of infections and deaths worldwide. Vaccines have been developed and authorized but supply of these vaccines is currently limited. With new variants of the virus now emerging and spreading globally, it is essential to develop therapeutics that are broadly protective and bind conserved epitopes in the receptor binding domain (RBD) or the whole spike of SARS-CoV-2. In this study, we have generated mouse monoclonal antibodies (mAbs) against different epitopes on the RBD and assessed binding and neutralization against authentic SARS-CoV-2. We have demonstrated that antibodies with neutralizing activity, but not non-neutralizing antibodies, lower viral titers in the lungs when administered in a prophylactic setting in vivo in a mouse challenge model. In addition, most of the mAbs cross-neutralize the B.1.351 as well as the B.1.1.7 variants in vitro.

scholarly journals Development of inhibitory synaptic inputs on layer 2/3 pyramidal neurons in the rat medial prefrontal cortex

2018 ◽  
Author(s):  
Mari A. Virtanen ◽  
Claudia Marvine Lacoh ◽  
Hubert Fiumelli ◽  
Markus Kosel ◽  
Shiva Tyagarajan ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Medial Prefrontal Cortex ◽  
Pyramidal Neurons ◽  
Synaptic Inputs ◽  
Layer 2

scholarly journals Phase Coupled Firing of Prefrontal Parvalbumin Interneuron With High Frequency Oscillations

2020 ◽  
Vol 14 ◽  
Author(s):  
Yanting Yao ◽  
Mengmeng Wu ◽  
Lina Wang ◽  
Longnian Lin ◽  
Jiamin Xu
Keyword(s):  
High Frequency ◽  
Pyramidal Neurons ◽  
Temporal Dynamics ◽  
Gamma Oscillations ◽  
Cognitive Behaviors ◽  
Firing Rates ◽  
High Frequency Oscillations ◽  
Electrophysiological Recordings ◽  
Parvalbumin Interneuron

The prefrontal cortex (PFC) plays a central role in executive functions and inhibitory control over many cognitive behaviors. Dynamic changes in local field potentials (LFPs), such as gamma oscillation, have been hypothesized to be important for attentive behaviors and modulated by local interneurons such as parvalbumin (PV) cells. However, the precise relationships between the firing patterns of PV interneurons and temporal dynamics of PFC activities remains elusive. In this study, by combining in vivo electrophysiological recordings with optogenetics, we investigated the activities of prefrontal PV interneurons and categorized them into three subtypes based on their distinct firing rates under different behavioral states. Interestingly, all the three subtypes of interneurons showed strong phase-locked firing to cortical high frequency oscillations (HFOs), but not to theta or gamma oscillations, despite of behavior states. Moreover, we showed that sustained optogenetic stimulation (over a period of 10 s) of PV interneurons can consequently modulate the activities of local pyramidal neurons. Interestingly, such optogenetic manipulations only showed moderate effects on LFPs in the PFC. We conclude that prefrontal PV interneurons are consist of several subclasses of cells with distinct state-dependent modulation of firing rates, selectively coupled to HFOs.

scholarly journals Amygdala inputs drive feedforward inhibition in the medial prefrontal cortex

2013 ◽  
Vol 110 (1) ◽  
pp. 221-229 ◽  
Author(s):  
Jonathan Dilgen ◽  
Hugo A. Tejeda ◽  
Patricio O'Donnell
Keyword(s):  
Prefrontal Cortex ◽  
Basolateral Amygdala ◽  
Pyramidal Neurons ◽  
Reversal Potential ◽  
Intracellular Recordings ◽  
Action Potential Firing ◽  
Gaba A ◽  
Potential Firing ◽  
Feedforward Inhibition

Although interactions between the amygdala and prefrontal cortex (PFC) are critical for emotional guidance of behavior, the manner in which amygdala affects PFC function is not clear. Whereas basolateral amygdala (BLA) output neurons exhibit many characteristics associated with excitatory neurotransmission, BLA stimulation typically inhibits PFC cell firing. This apparent discrepancy could be explained if local PFC inhibitory interneurons were activated by BLA inputs. Here, we used in vivo juxtacellular and intracellular recordings in anesthetized rats to investigate whether BLA inputs evoke feedforward inhibition in the PFC. Juxtacellular recordings revealed that BLA stimulation evoked action potentials in PFC interneurons and silenced most pyramidal neurons. Intracellular recordings from PFC pyramidal neurons showed depolarizing postsynaptic potentials, with multiple components evoked by BLA stimulation. These responses exhibited a relatively negative reversal potential (Erev), suggesting the contribution of a chloride component. Intracellular administration or pressure ejection of the GABA-A antagonist picrotoxin resulted in action-potential firing during the BLA-evoked response, which had a more depolarized Erev. These results suggest that BLA stimulation engages a powerful inhibitory mechanism within the PFC mediated by local circuit interneurons.

scholarly journals (R)-Ketamine Induces a Greater Increase in Prefrontal 5-HT Release Than (S)-Ketamine and Ketamine Metabolites via an AMPA Receptor-Independent Mechanism

2019 ◽  
Vol 22 (10) ◽  
pp. 665-674 ◽  
Author(s):  
Yukio Ago ◽  
Wataru Tanabe ◽  
Momoko Higuchi ◽  
Shinji Tsukada ◽  
Tatsunori Tanaka ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Ampa Receptor ◽  
Dopamine Release ◽  
Molecular Mechanisms ◽  
In Vivo Microdialysis ◽  
Serotonin Release ◽  
Dependent Manner ◽  
Independent Mechanism ◽  
Dose Dependent

Abstract Background Although recent studies provide insight into the molecular mechanisms of the effects of ketamine, the antidepressant mechanism of ketamine enantiomers and their metabolites is not fully understood. In view of the involvement of mechanisms other than the N-methyl-D-aspartate receptor in ketamine’s action, we investigated the effects of (R)-ketamine, (S)-ketamine, (R)-norketamine [(R)-NK], (S)-NK, (2R,6R)-hydroxynorketamine [(2R,6R)-HNK], and (2S,6S)-HNK on monoaminergic neurotransmission in the prefrontal cortex of mice. Methods The extracellular monoamine levels in the prefrontal cortex were measured by in vivo microdialysis. Results (R)-Ketamine and (S)-ketamine acutely increased serotonin release in a dose-dependent manner, and the effect of (R)-ketamine was greater than that of (S)-ketamine. In contrast, (S)-ketamine caused a robust increase in dopamine release compared with (R)-ketamine. Both ketamine enantiomers increased noradrenaline release, but these effects did not differ. (2R,6R)-HNK caused a slight but significant increase in serotonin and noradrenaline but not dopamine release. (S)-NK increased dopamine and noradrenaline but not serotonin release. Differential effects between (R)-ketamine and (S)-ketamine were also observed in a lipopolysaccharide-induced model of depression. An α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor antagonist, 2,3-dioxo-6-nitro-1,2,3,4- tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX), attenuated (S)-ketamine-induced, but not (R)-ketamine-induced serotonin release, whereas NBQX blocked dopamine release induced by both enantiomers. Local application of (R)-ketamine into the prefrontal cortex caused a greater increase in prefrontal serotonin release than that of (S)-ketamine. Conclusions (R)-Ketamine strongly activates the prefrontal serotonergic system through an AMPA receptor-independent mechanism. (S)-Ketamine-induced serotonin and dopamine release was AMPA receptor-dependent. These findings provide a neurochemical basis for the underlying pharmacological differences between ketamine enantiomers and their metabolites.

scholarly journals Secalonic Acid-F, a Novel Mycotoxin, Represses the Progression of Hepatocellular Carcinoma via MARCH1 Regulation of the PI3K/AKT/β-catenin Signaling Pathway

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 393 ◽  
Author(s):  
Lulu Xie ◽  
Minjing Li ◽  
Desheng Liu ◽  
Xia Wang ◽  
Peiyuan Wang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Liver Cancer ◽  
Mouse Model ◽  
Colony Formation ◽  
Migration And Invasion ◽  
Dependent Manner ◽  
Small Interfering Rnas ◽  
Nude Mouse Model ◽  
Hep3b Cells

Liver cancer is a very common and significant health problem. Therefore, powerful molecular targeting agents are urgently needed. Previously, we demonstrated that secalonic acid-F (SAF) suppresses the growth of hepatocellular carcinoma (HCC) cells (HepG2), but the other anticancer biological functions and the underlying mechanism of SAF on HCC are unknown. In this study, we found that SAF, which was isolated from a fungal strain in our lab identified as Aspergillus aculeatus, could inhibit the progression of hepatocellular carcinoma by targeting MARCH1, which regulates the PI3K/AKT/β-catenin and antiapoptotic Mcl-1/Bcl-2 signaling cascades. First, we confirmed that SAF reduced the proliferation and colony formation of HCC cell lines (HepG2 and Hep3B), promoted cell apoptosis, and inhibited the cell cycle in HepG2 and Hep3B cells in a dose-dependent manner. In addition, the migration and invasion of HepG2 and Hep3B cells treated with SAF were significantly suppressed. Western blot analysis showed that the level of MARCH1 was downregulated by pretreatment with SAF through the regulation of the PI3K/AKT/β-catenin signaling pathways. Moreover, knockdown of MARCH1 by small interfering RNAs (siRNAs) targeting MARCH1 also suppressed the proliferation, colony formation, migration, and invasion as well as increased the apoptotic rate of HepG2 and Hep3B cells. These data confirmed that the downregulation of MARCH1 could inhibit the progression of hepatocellular carcinoma and that the mechanism may be via PI3K/AKT/β-catenin inactivation as well as the downregulation of the antiapoptotic Mcl-1/Bcl-2. In vivo, the downregulation of MARCH1 by treatment with SAF markedly inhibited tumor growth, suggesting that SAF partly blocks MARCH1 and further regulates the PI3K/AKT/β-catenin and antiapoptosis Mcl-1/Bcl-2 signaling cascade in the HCC nude mouse model. Additionally, the apparent diffusion coefficient (ADC) values, derived from magnetic resonance imaging (MRI), were increased in tumors after SAF treatment in a mouse model. Taken together, our findings suggest that MARCH1 is a potential molecular target for HCC treatment and that SAF is a promising agent targeting MARCH1 to treat liver cancer patients.

scholarly journals P062 Dose-dependent differential effects of vedolizumab therapy on adhesion of regulatory and effector T cells

2020 ◽  
Vol 14 (Supplement_1) ◽  
pp. S165-S166
Author(s):  
E Becker ◽  
M Wiendl ◽  
A Schulz-Kuhnt ◽  
I Atreya ◽  
R Atreya ◽  
...  
Keyword(s):  
T Cell ◽  
Mouse Model ◽  
T Cell Subsets ◽  
Dependent Manner ◽  
Differential Effects ◽  
Preferential Binding ◽  
Exposure Levels ◽  
Differential Binding ◽  
Dose Dependent

Abstract Background Vedolizumab has emerged as an important pillar of treatment in inflammatory bowel disease (IBD). However, for unknown reasons, not all patients respond to therapy. Earlier clinical studies suggested decreased response rates in the highest compared with medium dosage groups. Interestingly, vedolizumab has been shown to inhibit the homing of both regulatory (Treg) and effector T (Teff) cells and previous data from our group suggested different effect sizes in both populations. Thus, we hypothesised that the non-linear exposure–efficacy correlation might be explained by dose-dependent differential effects of vedolizumab on Treg and Teff homing. Therefore, we studied functional effects of different vedolizumab exposure levels on Treg and Teff cell trafficking. Methods The α4β7 expression on different human T-cell subsets as well as the binding characteristics of vedolizumab to these cells at different exposure levels was analysed via flow cytometry. Functional effects of different vedolizumab concentrations on the adhesion of Tregs and Teffs to mucosal addressin cell adhesion molecule 1 (MAdCAM-1) were analysed using dynamic in vitro adhesion assays, transmigration assays and in vivo homing assays in a humanised mouse model. The in vivo binding of vedolizumab to Tregs and Teffs in patients receiving therapy was quantified and correlated with the corresponding serum levels. Results We found a preferential binding of vedolizumab to Tregs at an exposure with 0.4 µg/ml vedolizumab that shifted to a preferential binding to Teffs at an exposure with 10 µg/ml. Further increase of vedolizumab to 50 µg/ml led to equal binding to Tregs and Teffs (Figure 1). Consistently, at 10 µg/ml, dynamic adhesion of Tregs to MAdCAM-1 was increased compared with Teffs, but no difference was noted at 50 µg/ml. Additionally, a higher number of Treg compared with Teff cells were able to transmigrate in a MAdCAM-1-dependent manner at a concentration of 10 µg/ml vedolizumab. Preliminary data from homing experiments in a humanised mouse model and from IBD patients treated with vedolizumab support the notion that differential binding preferences depending on the exposure level can also be observed in vivo. Conclusion Our findings support a dose-dependent differential binding of vedolizumab to different T-cell subpopulations and suggest that an optimal ‘window’ of exposure exists, in which effects on Teffs predominate over Tregs. While offering a potential explanation for earlier findings in dose-ranging studies, our data might lay the basis for the establishment of individualised dose optimisation in IBD patients.

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