scholarly journals Microglia Depletion-Induced Remodeling of Extracellular Matrix and Excitatory Synapses in the Hippocampus of Adult Mice

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1862
Author(s):  
Luisa Strackeljan ◽  
Ewa Baczynska ◽  
Carla Cangalaya ◽  
David Baidoe-Ansah ◽  
Jakub Wlodarczyk ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Pyramidal Neurons ◽  
Physiological Role ◽  
Ecm Remodeling ◽  
Ca1 Region ◽  
Adult Mice ◽  
Elevated Expression ◽  
Gabaergic Synapses ◽  
The Central Nervous System ◽  
Remodeling Of Extracellular Matrix

The extracellular matrix (ECM) plays a key role in synaptogenesis and the regulation of synaptic functions in the central nervous system. Recent studies revealed that in addition to dopaminergic and serotoninergic neuromodulatory systems, microglia also contribute to the regulation of ECM remodeling. In the present work, we investigated the physiological role of microglia in the remodeling of perineuronal nets (PNNs), predominantly associated with parvalbumin-immunopositive (PV+) interneurons, and the perisynaptic ECM around pyramidal neurons in the hippocampus. Adult mice were treated with PLX3397 (pexidartinib), as the inhibitor of colony-stimulating factor 1 receptor (CSF1-R), to deplete microglia. Then, confocal analysis of the ECM and synapses was performed. Although the elimination of microglia did not alter the overall number or intensity of PNNs in the CA1 region of the hippocampus, it decreased the size of PNN holes and elevated the expression of the surrounding ECM. In the neuropil area in the CA1 str. radiatum, the depletion of microglia increased the expression of perisynaptic ECM proteoglycan brevican, which was accompanied by the elevated expression of presynaptic marker vGluT1 and the increased density of dendritic spines. Thus, microglia regulate the homeostasis of pre- and postsynaptic excitatory terminals and the surrounding perisynaptic ECM as well as the fine structure of PNNs enveloping perisomatic—predominantly GABAergic—synapses.

scholarly journals Glycosaminoglycans role in hippocampal neural networks interneuronal communications

2020 ◽  
Vol 64 (5) ◽  
pp. 590-598
Author(s):  
S. G. Pashkevich ◽  
N. S. Serdyuchenko
Keyword(s):  
Extracellular Matrix ◽  
Nervous Tissue ◽  
Therapeutic Effects ◽  
Preliminary Screening ◽  
Ca1 Region ◽  
Medicinal Substances ◽  
The Central Nervous System ◽  
Glycosaminoglycan Metabolism ◽  
Electrical Impulses

In the development of neurotechnologies, the search for applications for invasive neuroelectronic devices is relevant. One of the promising areas can be the development of ways of influencing intercellular communication, that is, not by acting on pre-, post- and extrasynaptic receptors, but on the extracellular matrix surrounding neurons and glia. For the development of bioelectronic pharmaceuticals, it is important to search for stimulation parameters at which a controlled change in the structural and functional parameters of the nervous tissue is possible. We considered one of the actual mechanisms of the molecular pathogenesis of SARS-CoV-2 infection - the induction of glycosaminoglycan metabolism. It is assumed that, getting into the olfactory epithelium and the olfactory bulbs of the brain, the virus is able to reach the structures of the central nervous system. When modeling changes in the enzymatic activity of hyaluronidase (0.1; 1.0; 10.0 U/ml) for 5 minutes in one of the key structures of the limbic system - the hippocampus (3-4-week-old ratpups, n = 64), the conditions for the transformation of intercellular contacts were revealed and evoked electrical activity of populations of CA1 region. The recorded development of synaptic plasticity processes has an adaptive potential at hyaluronidase concentrations not exceeding 1.0 U/ml.The in vitro method proposed in this work and a reasonable target for exposure - elements of the extracellular matrix, make it possible to simulate one of the mechanisms of the development of viral infection, optimize the process of preliminary screening of new medicinal substances that can minimize the risk of developing neuroinflammatory processes, and also substantiate the conditions for safe and/or therapeutic effects and electrical impulses on the elements of the nervous tissue.

scholarly journals Increased Calbindin D28k Expression via Long-Term Alternate-Day Fasting Does Not Protect against Ischemia-Reperfusion Injury: A Focus on Delayed Neuronal Death, Gliosis and Immunoglobulin G Leakage

2021 ◽  
Vol 22 (2) ◽  
pp. 644
Author(s):  
Hyejin Sim ◽  
Tae-Kyeong Lee ◽  
Yeon Ho Yoo ◽  
Ji Hyeon Ahn ◽  
Dae Won Kim ◽  
...  
Keyword(s):  
Immunoglobulin G ◽  
Pyramidal Neurons ◽  
Short Term Memory ◽  
Forebrain Ischemia ◽  
Short Term ◽  
Term Memory ◽  
Transient Forebrain Ischemia ◽  
Ca1 Pyramidal Neurons ◽  
Ca1 Region ◽  
Calbindin D28k

Calbindin-D28k (CB), a calcium-binding protein, mediates diverse neuronal functions. In this study, adult gerbils were fed a normal diet (ND) or exposed to intermittent fasting (IF) for three months, and were randomly assigned to sham or ischemia operated groups. Ischemic injury was induced by transient forebrain ischemia for 5 min. Short-term memory was examined via passive avoidance test. CB expression was investigated in the Cornu Ammonis 1 (CA1) region of the hippocampus via western blot analysis and immunohistochemistry. Finally, histological analysis was used to assess neuroprotection and gliosis (microgliosis and astrogliosis) in the CA1 region. Short-term memory did not vary significantly between ischemic gerbils with IF and those exposed to ND. CB expression was increased significantly in the CA1 pyramidal neurons of ischemic gerbils with IF compared with that of gerbils fed ND. However, the CB expression was significantly decreased in ischemic gerbils with IF, similarly to that of ischemic gerbils exposed to ND. The CA1 pyramidal neurons were not protected from ischemic injury in both groups, and gliosis (astrogliosis and microgliosis) was gradually increased with time after ischemia. In addition, immunoglobulin G was leaked into the CA1 parenchyma from blood vessels and gradually increased with time after ischemic insult in both groups. Taken together, our study suggests that IF for three months increases CB expression in hippocampal CA1 pyramidal neurons; however, the CA1 pyramidal neurons are not protected from transient forebrain ischemia. This failure in neuroprotection may be attributed to disruption of the blood–brain barrier, which triggers gliosis after ischemic insults.

scholarly journals High levels of 27-hydroxycholesterol results in synaptic plasticity alterations in the hippocampus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Raul Loera-Valencia ◽  
Erika Vazquez-Juarez ◽  
Alberto Muñoz ◽  
Gorka Gerenu ◽  
Marta Gómez-Galán ◽  
...  
Keyword(s):  
Pyramidal Neurons ◽  
Memory Function ◽  
Long Term Potentiation ◽  
Synaptic Function ◽  
Cholesterol Homeostasis ◽  
Stratum Radiatum ◽  
Actin Binding ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Term Potentiation

AbstractAlterations in brain cholesterol homeostasis in midlife are correlated with a higher risk of developing Alzheimer’s disease (AD). However, global cholesterol-lowering therapies have yielded mixed results when it comes to slowing down or preventing cognitive decline in AD. We used the transgenic mouse model Cyp27Tg, with systemically high levels of 27-hydroxycholesterol (27-OH) to examine long-term potentiation (LTP) in the hippocampal CA1 region, combined with dendritic spine reconstruction of CA1 pyramidal neurons to detect morphological and functional synaptic alterations induced by 27-OH high levels. Our results show that elevated 27-OH levels lead to enhanced LTP in the Schaffer collateral-CA1 synapses. This increase is correlated with abnormally large dendritic spines in the stratum radiatum. Using immunohistochemistry for synaptopodin (actin-binding protein involved in the recruitment of the spine apparatus), we found a significantly higher density of synaptopodin-positive puncta in CA1 in Cyp27Tg mice. We hypothesize that high 27-OH levels alter synaptic potentiation and could lead to dysfunction of fine-tuned processing of information in hippocampal circuits resulting in cognitive impairment. We suggest that these alterations could be detrimental for synaptic function and cognition later in life, representing a potential mechanism by which hypercholesterolemia could lead to alterations in memory function in neurodegenerative diseases.

scholarly journals Expression and Function of Organic Anion Transporting Polypeptides in the Human Brain: Physiological and Pharmacological Implications

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 834
Author(s):  
Anima M. Schäfer ◽  
Henriette E. Meyer zu Schwabedissen ◽  
Markus Grube
Keyword(s):  
Organic Anion ◽  
Physiological Role ◽  
Point Of View ◽  
Efflux Transporters ◽  
Organic Anion Transporting Polypeptides ◽  
Current State ◽  
P Glycoprotein ◽  
The Central Nervous System ◽  
And Function ◽  
Uptake Transporters

The central nervous system (CNS) is an important pharmacological target, but it is very effectively protected by the blood–brain barrier (BBB), thereby impairing the efficacy of many potential active compounds as they are unable to cross this barrier. Among others, membranous efflux transporters like P-Glycoprotein are involved in the integrity of this barrier. In addition to these, however, uptake transporters have also been found to selectively uptake certain compounds into the CNS. These transporters are localized in the BBB as well as in neurons or in the choroid plexus. Among them, from a pharmacological point of view, representatives of the organic anion transporting polypeptides (OATPs) are of particular interest, as they mediate the cellular entry of a variety of different pharmaceutical compounds. Thus, OATPs in the BBB potentially offer the possibility of CNS targeting approaches. For these purposes, a profound understanding of the expression and localization of these transporters is crucial. This review therefore summarizes the current state of knowledge of the expression and localization of OATPs in the CNS, gives an overview of their possible physiological role, and outlines their possible pharmacological relevance using selected examples.

scholarly journals Engineering cardiac microphysiological systems to model pathological extracellular matrix remodeling

2018 ◽  
Vol 315 (4) ◽  
pp. H771-H789 ◽  
Author(s):  
Nethika R. Ariyasinghe ◽  
Davi M. Lyra-Leite ◽  
Megan L. McCain
Keyword(s):  
Cardiovascular Disease ◽  
Extracellular Matrix ◽  
Myocardial Function ◽  
Myocardial Cell ◽  
Three Dimensions ◽  
Model Systems ◽  
Matrix Remodeling ◽  
Ecm Remodeling ◽  
Microphysiological Systems

Many cardiovascular diseases are associated with pathological remodeling of the extracellular matrix (ECM) in the myocardium. ECM remodeling is a complex, multifactorial process that often contributes to declines in myocardial function and progression toward heart failure. However, the direct effects of the many forms of ECM remodeling on myocardial cell and tissue function remain elusive, in part because conventional model systems used to investigate these relationships lack robust experimental control over the ECM. To address these shortcomings, microphysiological systems are now being developed and implemented to establish direct relationships between distinct features in the ECM and myocardial function with unprecedented control and resolution in vitro. In this review, we will first highlight the most prominent characteristics of ECM remodeling in cardiovascular disease and describe how these features can be mimicked with synthetic and natural biomaterials that offer independent control over multiple ECM-related parameters, such as rigidity and composition. We will then detail innovative microfabrication techniques that enable precise regulation of cellular architecture in two and three dimensions. We will also describe new approaches for quantifying multiple aspects of myocardial function in vitro, such as contractility, action potential propagation, and metabolism. Together, these collective technologies implemented as cardiac microphysiological systems will continue to uncover important relationships between pathological ECM remodeling and myocardial cell and tissue function, leading to new fundamental insights into cardiovascular disease, improved human disease models, and novel therapeutic approaches.

scholarly journals A High-Throughput Workflow to Study Remodeling of Extracellular Matrix-Based Microtissues

2019 ◽  
Vol 25 (1) ◽  
pp. 25-36 ◽  
Author(s):  
Alexandra L. Crampton ◽  
Katherine A. Cummins ◽  
David K. Wood
Keyword(s):  
Extracellular Matrix ◽  
High Throughput ◽  
Remodeling Of Extracellular Matrix

scholarly journals Lack of change in CA1 dendritic spine density or clustering in rats following training on a radial-arm maze task

2020 ◽  
Vol 5 ◽  
pp. 68
Author(s):  
Emma Craig ◽  
Christopher M. Dillingham ◽  
Michal M. Milczarek ◽  
Heather M. Phillips ◽  
Moira Davies ◽  
...  
Keyword(s):  
Dendritic Spines ◽  
Pyramidal Neurons ◽  
Memory Load ◽  
Spatial Location ◽  
Memory Formation ◽  
Spatial Task ◽  
Radial Arm Maze ◽  
Nearest Neighbour ◽  
Spine Density ◽  
Ca1 Region

Background: Neuronal plasticity is thought to underlie learning and memory formation. The density of dendritic spines in the CA1 region of the hippocampus has been repeatedly linked to mnemonic processes. Both the number and spatial location of the spines, in terms of proximity to nearest neighbour, have been implicated in memory formation. To examine how spatial training impacts synaptic structure in the hippocampus, Lister-Hooded rats were trained on a hippocampal-dependent spatial task in the radial-arm maze.  Methods: One group of rats were trained on a hippocampal-dependent spatial task in the radial arm maze. Two further control groups were included: a yoked group which received the same sensorimotor stimulation in the radial-maze but without a memory load, and home-cage controls. At the end of behavioural training, the brains underwent Golgi staining. Spines on CA1 pyramidal neuron dendrites were imaged and quantitatively assessed to provide measures of density and distance from nearest neighbour.  Results: There was no difference across behavioural groups either in terms of spine density or in the clustering of dendritic spines. Conclusions: Spatial learning is not always accompanied by changes in either the density or clustering of dendritic spines on the basal arbour of CA1 pyramidal neurons when assessed using Golgi imaging.

scholarly journals PDCD4–MAPK–NF-κB Positive Loop Simultaneously Promotes Microglia Activation and Neuron Apoptosis During Neuroinflammation

2021 ◽  
Author(s):  
Quan Chen ◽  
Hongjian Lu ◽  
Chengwei Duan ◽  
Xiangyang Zhu ◽  
Yi Zhang ◽  
...  
Keyword(s):  
Nuclear Translocation ◽  
Inflammatory Diseases ◽  
Damage Model ◽  
Pdcd4 Expression ◽  
Proapoptotic Protein ◽  
Inflammatory Activation ◽  
Elevated Expression ◽  
The Central Nervous System ◽  
Signaling Activation

Abstract Neuroinflammation and neuron injury are common features of the central nervous system (CNS) diseases. It is of great significance to identify their shared regulatory mechanisms and explore the potential therapeutic targets. Programmed cell death factor 4 (PDCD4), an apoptosis-related molecule, extensively participates in tumorigenesis and inflammatory diseases, but its expression and biological function during CNS neuroinflammation remain unclear. In the present study, utilizing the lipopolysaccharide (LPS)-induced neuroinflammation model in mice, we reported an elevated expression of PDCD4 both in injured neurons and activated microglia of the inflamed brain. A similar change in PDCD4 expression was observed in vitro in the microglial activation model. Silencing PDCD4 by shRNA significantly inhibited the phosphorylation of MAPKs (p38, ERK, and JNK), prevented the phosphorylation and nuclear translocation of NF-κB p65, and thus attenuated the LPS-induced microglial inflammatory activation. Interestingly, LPS also required the MAPK/NF-κB signaling activation to boost PDCD4 expression in microglia, indicating the presence of a positive loop. Moreover, a persistent elevation of PDCD4 expression was detected in the H2O2-induced neuronal oxidative damage model. Knocking down PDCD4 significantly inhibited the expression of proapoptotic protein BAX, suggesting the proapoptotic activity of PDCD4 in neurons. Taken together, our data indicated that PDCD4 may serve as a hub regulatory molecule that simultaneously promotes the microglial inflammatory activation and the oxidative stress-induced neuronal apoptosis within CNS. The microglial PDCD4–MAPK–NF-κB positive feedback loop may exaggerate the vicious cycle of neuroinflammation and neuronal injury and thus may become a potential therapeutic target for neuroinflammatory diseases.

scholarly journals Differential Requirement of DICER1 Activity during Development of Mitral and Tricuspid Valves

2022 ◽  
Author(s):  
Shun Yan ◽  
Yin Peng ◽  
Jin Lu ◽  
Saima Shakil ◽  
Yang Shi ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Tricuspid Valve ◽  
Regulatory Mechanisms ◽  
Mitral Valve Stenosis ◽  
Sequencing Analysis ◽  
Ecm Remodeling ◽  
Mitral Valves ◽  
Valve Development ◽  
Single Cell Rna Sequencing ◽  
Cell Sources

Mitral and tricuspid valves are essential for unidirectional blood flow in the heart. They are derived from similar cell sources, and yet congenital dysplasia affecting both valves is clinically rare, suggesting the presence of differential regulatory mechanisms underlying their development. We specifically inactivated Dicer1 in the endocardium during cardiogenesis, and unexpectedly found that Dicer1-deletion caused congenital mitral valve stenosis and regurgitation, while it had no impact on other valves. We showed that hyperplastic mitral valves were caused by abnormal condensation and extracellular matrix (ECM) remodeling. Our single-cell RNA Sequencing analysis revealed impaired maturation of mesenchymal cells and abnormal expression of ECM genes in mutant mitral valves. Furthermore, expression of a set of miRNAs that target ECM genes was significantly lower in tricuspid valves compared to mitral valves, consistent with the idea that the miRNAs are differentially required for mitral and tricuspid valve development. Our study thus reveals miRNA-mediated gene regulation as a novel molecular mechanism that differentially regulates mitral and tricuspid valve development, thereby enhancing our understanding of the non-association of inborn mitral and tricuspid dysplasia observed clinically.

scholarly journals Serotonin Transporter Defect Disturbs Structure and Function of the Auditory Cortex in Mice

2021 ◽  
Vol 15 ◽  
Author(s):  
Wenlu Pan ◽  
Jing Pan ◽  
Yan Zhao ◽  
Hongzheng Zhang ◽  
Jie Tang
Keyword(s):  
Auditory Cortex ◽  
Serotonin Transporter ◽  
Cortical Neurons ◽  
Pyramidal Neurons ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Neuronal Morphology ◽  
Neuronal Connections ◽  
The Central Nervous System ◽  
And Function

Serotonin transporter (SERT) modulates the level of 5-HT and significantly affects the activity of serotonergic neurons in the central nervous system. The manipulation of SERT has lasting neurobiological and behavioral consequences, including developmental dysfunction, depression, and anxiety. Auditory disorders have been widely reported as the adverse events of these mental diseases. It is unclear how SERT impacts neuronal connections/interactions and what mechanism(s) may elicit the disruption of normal neural network functions in auditory cortex. In the present study, we report on the neuronal morphology and function of auditory cortex in SERT knockout (KO) mice. We show that the dendritic length of the fourth layer (L-IV) pyramidal neurons and the second-to-third layer (L-II/III) interneurons were reduced in the auditory cortex of the SERT KO mice. The number and density of dendritic spines of these neurons were significantly less than those of wild-type neurons. Also, the frequency-tonotopic organization of primary auditory cortex was disrupted in SERT KO mice. The auditory neurons of SERT KO mice exhibited border frequency tuning with high-intensity thresholds. These findings indicate that SERT plays a key role in development and functional maintenance of auditory cortical neurons. Auditory function should be examined when SERT is selected as a target in the treatment for psychiatric disorders.

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