scholarly journals Septal cholinergic input to CA2 hippocampal region controls social novelty discrimination via nicotinic receptor-mediated disinhibition

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Domenico Pimpinella ◽  
Valentina Mastrorilli ◽  
Corinna Giorgi ◽  
Silke Coemans ◽  
Salvatore Lecca ◽  
...  
Keyword(s):  
Social Memory ◽  
Ex Vivo ◽  
Hippocampal Slices ◽  
Cholinergic Neurons ◽  
Underlying Mechanism ◽  
Medial Septum ◽  
Principal Cells ◽  
Diagonal Band ◽  
Social Novelty Discrimination

Acetylcholine (ACh), released in the hippocampus from fibers originating in the medial septum/diagonal band of Broca (MSDB) complex, is crucial for learning and memory. The CA2 region of the hippocampus has received increasing attention in the context of social memory. However, the contribution of ACh to this process remains unclear. Here, we show that in mice, ACh controls social memory. Specifically, MSDB cholinergic neurons inhibition impairs social novelty discrimination, meaning the propensity of a mouse to interact with a novel rather than a familiar conspecific. This effect is mimicked by a selective antagonist of nicotinic AChRs delivered in CA2. Ex vivo recordings from hippocampal slices provide insight into the underlying mechanism, as activation of nAChRs by nicotine increases the excitatory drive to CA2 principal cells via disinhibition. In line with this observation, optogenetic activation of cholinergic neurons in MSDB increases the firing of CA2 principal cells in vivo. These results point to nAChRs as essential players in social novelty discrimination by controlling inhibition in the CA2 region.

scholarly journals Functional Calsequestrin-1 Is Expressed in the Heart and Its Deficiency Is Causally Related to Malignant Hyperthermia-Like Arrhythmia

Circulation ◽  
2021 ◽  
Author(s):  
Zhipeng Sun ◽  
Luqi Wang ◽  
Lu Han ◽  
Yue Wang ◽  
Yuan Zhou ◽  
...  
Keyword(s):  
Heart Rate ◽  
Ventricular Tachycardia ◽  
Malignant Hyperthermia ◽  
Ex Vivo ◽  
Heat Stroke ◽  
Time Lapse ◽  
Underlying Mechanism ◽  
Neonatal Rat ◽  
Polymorphic Ventricular Tachycardia

Background: Calsequestrins (Casqs), comprising the Casq1 and Casq2 isoforms, buffer Ca 2+ and regulate its release in the sarcoplasmic reticulum (SR) of skeletal and cardiac muscle, respectively. Human inherited diseases associated with mutations in CASQ1 or CASQ2 include malignant hyperthermia/environmental heat stroke (MH/EHS) and catecholaminergic polymorphic ventricular tachycardia. However, patients with an MH/EHS event often suffer from arrhythmia for which the underlying mechanism remains unknown. Methods: Working hearts from conventional ( Casq1 -KO) and cardiac-specific ( Casq1 -CKO) Casq1 knockout mice were monitored in vivo and ex vivo by electrocardiogram and electrical mapping, respectively. MH was induced by 2% isoflurane and treated intraperitoneally with dantrolene. Time-lapse imaging was used to monitor intracellular Ca 2+ activity in isolated mouse cardiomyocytes or neonatal rat ventricular myocytes (NRVMs) with knockdown, over-expression or truncation of the Casq1 gene. Conformational change in both Casqs was determined by crosslinking Western blot analysis. Results: Like MH/EHS patients, Casq1 -KO and Casq1 -CKO mice had faster basal heart rate, and ventricular tachycardia upon exposure to 2% isoflurane, which could be relieved by dantrolene. Basal sinus tachycardia and ventricular ectopic electrical triggering also occurred in Casq1 -KO hearts ex vivo . Accordingly, the ventricular cardiomyocytes from Casq1 -CKO mice displayed dantrolene-sensitive increased Ca 2+ waves and diastole premature Ca 2+ transients/oscillations upon isoflurane. NRVMs with Casq1-knockdown had enhanced spontaneous Ca2+ sparks/transients upon isoflurane, while cells over-expressing Casq1 exhibited decreased Ca2+ sparks/transients that were absent in cells with truncation of 9 amino acids at the C-terminus of Casq1. Structural evaluation showed that most of the Casq1 protein was present as a polymer and physically interacted with RyR2 in the ventricular SR. The Casq1 isoform was also expressed in human myocardium. Mechanistically, exposure to 2% isoflurane or heating at 41ºC induced Casq1 oligomerization in mouse ventricular and skeletal muscle tissues, leading to a reduced Casq1/RyR2 interaction and increased RyR2 activity in the ventricle. Conclusions: Casq1 is expressed in the heart, where it regulates SR Ca 2+ release and heart rate. Casq1 deficiency independently causes MH/EHS-like ventricular arrhythmia by trigger-induced Casq1 oligomerization and a relief of its inhibitory effect on RyR2-mediated Ca 2+ release, thus revealing a new inherited arrhythmia and a novel mechanism for MH/EHS arrhythmogenesis.

scholarly journals Effects of CYP46A1 Inhibition on Long-Term-Depression in Hippocampal Slices ex vivo and 24S-Hydroxycholesterol Levels in Mice in vivo

2020 ◽  
Vol 13 ◽  
Author(s):  
Michael Popiolek ◽  
Yukitoshi Izumi ◽  
Allen T. Hopper ◽  
Jing Dai ◽  
Silke Miller ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Hippocampal Slices ◽  
Long Term Depression

scholarly journals Citrulline directly modulates muscle protein synthesis via the PI3K/MAPK/4E-BP1 pathway in a malnourished state: evidence from in vivo, ex vivo, and in vitro studies

2017 ◽  
Vol 312 (1) ◽  
pp. E27-E36 ◽  
Author(s):  
Servane Le Plénier ◽  
Arthur Goron ◽  
Athanassia Sotiropoulos ◽  
Eliane Archambault ◽  
Chantal Guihenneuc ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Ex Vivo ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Fold Increase ◽  
Underlying Mechanism ◽  
Muscle Homeostasis

Citrulline (CIT) is an endogenous amino acid produced by the intestine. Recent literature has consistently shown CIT to be an activator of muscle protein synthesis (MPS). However, the underlying mechanism is still unknown. Our working hypothesis was that CIT might regulate muscle homeostasis directly through the mTORC1/PI3K/MAPK pathways. Because CIT undergoes both interorgan and intraorgan trafficking and metabolism, we combined three approaches: in vivo, ex vivo, and in vitro. Using a model of malnourished aged rats, CIT supplementation activated the phosphorylation of S6K1 and 4E-BP1 in muscle. Interestingly, the increase in S6K1 phosphorylation was positively correlated ( P < 0.05) with plasma CIT concentration. In a model of isolated incubated skeletal muscle from malnourished rats, CIT enhanced MPS (from 30 to 80% CIT vs. Ctrl, P < 0.05), and the CIT effect was abolished in the presence of wortmannin, rapamycin, and PD-98059. In vitro, on myotubes in culture, CIT led to a 2.5-fold increase in S6K1 phosphorylation and a 1.5-fold increase in 4E-BP1 phosphorylation. Both rapamycin and PD-98059 inhibited the CIT effect on S6K1, whereas only LY-294002 inhibited the CIT effect on both S6K1 and 4E-BP1. These findings show that CIT is a signaling agent for muscle homeostasis, suggesting a new role of the intestine in muscle mass control.

scholarly journals The endomembrane system of cholinergic and non-cholinergic neurons in the medial septal nucleus and vertical limb of the diagonal band of Broca: a cytochemical and immunocytochemical study.

1990 ◽  
Vol 38 (4) ◽  
pp. 563-571 ◽  
Author(s):  
G Palacios
Keyword(s):  
Cholinergic Neurons ◽  
Medial Septum ◽  
Projection Neurons ◽  
Lamellar Bodies ◽  
Endomembrane System ◽  
Electron Microscopic ◽  
Diagonal Band ◽  
Diagonal Band Of Broca ◽  
Well Differentiated ◽  
Microscopic Morphology

Coronal vibratome sections of the rostral part of the medial septum (MS) and vertical limb of the diagonal band of Broca (VDB) nuclei were studied by an immunocytochemical technique using a monoclonal antibody against choline acetyltransferase (ChAT) and a double histochemical method for detection of acid phosphatase (AcPase) and nucleoside diphosphatase (NDPase) activity. The electron microscopic morphology of ChAT-immunoreactive and non-immunoreactive neurons was compared with similar neurons showing both AcPase and NDPase activity. ChAT-labeled and non-labeled neurons were well differentiated by the organization of the endomembrane system and especially by the structure of the rough endoplasmic reticulum (RER) and associated lamellar bodies. These results support the theory that the peculiar ultrastructure of the lamellar bodies in each neuron is related to the pattern of organization of the endomembrane system and its function. The significance of the lamellar bodies is discussed, and the data of the present work, together with findings described by other investigators. These data suggest that these bodies are predominant in efferent projection neurons in the basal forebrain nuclei.

scholarly journals Acute Ethanol Exposure Elevates Muscarinic Tone in the Septohippocampal System

2010 ◽  
Vol 103 (1) ◽  
pp. 290-296 ◽  
Author(s):  
Mia Ericson ◽  
Michelle A Sama ◽  
Hermes H. Yeh
Keyword(s):  
Direct Action ◽  
Cholinergic Neurons ◽  
Medial Septum ◽  
Ethanol Exposure ◽  
Neuronal Firing ◽  
Firing Activity ◽  
Diagonal Band ◽  
Acute Ethanol ◽  
Septohippocampal System ◽  
Methyl Scopolamine

The septohippocampal system has been implicated in the cognitive deficits associated with ethanol consumption, but the cellular basis of ethanol action awaits full elucidation. In the medial septum/diagonal band of Broca (MS/DB), a muscarinic tone, reflective of firing activity of resident cholinergic neurons, regulates that of their noncholinergic, putatively GABAergic, counterparts. Here we tested the hypothesis that ethanol alters this muscarinic tone. The spontaneous firing activity of cholinergic and noncholinergic MS/DB neurons were monitored in acute MS/DB slices from C57Bl/6 mice. Exposing the entire slice to ethanol increased firing in both cholinergic and noncholinergic neurons. However, applying ethanol focally to individual MS/DB neurons increased firing only in cholinergic neurons. The differential outcome suggested different mechanisms of ethanol action on cholinergic and noncholinergic neurons. Indeed, with bath-perfused ethanol, the muscarinic antagonist methyl scopolamine prevented the increase in firing in noncholinergic, but not cholinergic, MS/DB neurons. Thus, the effect on noncholinergic neuronal firing was secondary to ethanol's direct action of acutely increasing muscarinic tone. We propose that the acute ethanol-induced elevation of muscarinic tone in the MS/DB contributes to the altered net flow of neuronal activity in the septohippocampal system that underlies compromised cognitive function.

scholarly journals FSMP-09. FORMATE PROMOTES CANCER CELL INVASION AND METASTASIS VIA CALCIUM SIGNALING

2020 ◽  
Vol 3 (Supplement_1) ◽  
pp. i18-i18
Author(s):  
Catherine Delbrouck ◽  
Vitaly I Pozdeev ◽  
Anais Oudin ◽  
Kamil Grzyb ◽  
Laura Neises ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Ex Vivo ◽  
Tumor Model ◽  
Underlying Mechanism ◽  
Tumor Escape ◽  
Proliferating Cells ◽  
Nucleotide Synthesis ◽  
Formate Production

Abstract Serine catabolism via the folate cycle provides formate that is essential for nucleotide synthesis in proliferating cells. In addition to this canonical function to support biomass production in anabolic cells, we have recently demonstrated in vitro and in vivo that formate production in cancer cells is often in excess of the anabolic demand. This excess formate production is characterized by formate overflow and thus, net formate excretion into the tumor microenvironment. Interestingly, we observe increased rates of formate overflow upon different chemical perturbations that induce growth arrest. Thus, stressed cancer cells that encounter growth restriction such as upon chemotherapy, are often characterized by increased formate release rates. We demonstrated that such high formate levels in the extracellular space promote invasion of glioblastoma cells. Using ex vivo brain slice cultures and an orthotopic brain tumor model, we demonstrate that silencing MTHFD1L, the essential enzyme to enable formate overflow, results in decreased invasiveness of the tumor. Embarking from this observation, we investigated the underlying mechanism and now provide evidence that the formate-dependent increase of cell motility is mediated by an activation of Ca2+ signaling. Activation of Ca2+ signaling triggers integrin and matrix metallopeptidase (MMP) responses enabling the invasion process. Targeting either the Ca2+ response or MMP release can suppress the formate dependent increase in invasion. Finally, we tested the effect of formate also in context of breast cancer where we were able to recapitulate our observation of increased invasiveness and, in this case, formate also promoted the metastatic potential. We conclude that excreted formate might serve as a cellular stress signal that represents a promotive trigger to support tumor escape mechanisms.

scholarly journals Vasopressin acts as a synapse organizer in limbic regions by boosting PSD95 and GluA1 expression

2020 ◽  
Author(s):  
Limei Zhang ◽  
Teresa Padilla-Flores ◽  
Vito S. Hernández ◽  
Elba Campos-Lira ◽  
Mario A. Zetter ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Pyramidal Neurons ◽  
Ex Vivo ◽  
Hippocampal Slices ◽  
Brain Slices ◽  
Synaptic Proteins ◽  
Scaffolding Protein ◽  
Synaptic Organization ◽  
Limbic Regions

AbstractHypothalamic arginine vasopressin (AVP)-containing magnocellular neurosecretory neurons (AVPMNN) emit collaterals to synaptically innervate limbic regions influencing learning, motivational behavior and fear responses. The purpose of the present work is to characterize the dynamics of expression changes of two postsynaptic density (PSD) proteins, AMPAR subunit GluA1 and PSD scaffolding protein 95 (PSD95), which are known to be key determinants for synaptic strength, in response to in vivo and ex vivo manipulations of AVPMNN neuronal activation state, or exposure to exogenous AVP, metabolites and some signaling pathway inhibitors. Both long term water deprivation in vivo, which powerfully upregulates AVPMNN activity, and exogenous APV application ex vivo in brain slices, increased GluA1 and PSD95 expression and enhanced neuronal excitability in ventral hippocampal CA1 pyramidal neurons. Involvement of PI3k signaling in AVP-dependent plasticity is suggested by blockade of both AVP-induced protein up-regulation and enhanced neuronal excitability by the PI3k blocker wortmannin in hippocampal slices. We interpret these results as part of vasopressin’s central effects on synaptic organization in limbic regions modulating the strength of a specific set of synaptic proteins in hypothalamic-limbic circuits.Supported by grantsUNAM-DGAPA-PAPIIT-IN216918 & CONACYT-CB-238744.

scholarly journals 3D Organoid Culture From Adult Salivary Gland Tissues as an ex vivo Modeling of Salivary Gland Morphogenesis

2021 ◽  
Vol 9 ◽  
Author(s):  
Donghyun Kim ◽  
Yeo-Jun Yoon ◽  
Dojin Choi ◽  
Jisun Kim ◽  
Jae-Yol Lim
Keyword(s):  
Salivary Gland ◽  
Culture System ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Underlying Mechanism ◽  
Lumen Formation ◽  
Organoid Culture ◽  
Culture Models ◽  
Gland Morphogenesis

Lumen formation of salivary glands has been investigated using in vivo or ex vivo rudiment culture models. In this study, we used a three-dimensional (3D) salivary gland organoid culture system and demonstrated that lumen formation could be recapitulated in mouse SMG organoids. In our organoid culture system, lumen formation was induced by vasoactive intestinal peptide and accelerated by treatment with RA. Furthermore, lumen formation was observed in branching duct-like structure when cultured in combination of fibroblast growth factors (FGF) in the presence of retinoic acid (RA). We suggest RA signaling-mediated regulation of VIPR1 and KRT7 as the underlying mechanism for lumen formation, rather than apoptosis in the organoid culture system. Collectively, our results support a fundamental role for RA in lumen formation and demonstrate the feasibility of 3D organoid culture as a tool for studying salivary gland morphogenesis.

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