REVIEW | doi:10.20944/preprints202005.0488.v1
Subject: Keywords: striatal development; Huntington’s disease; spiny projection neurons; medium spiny neurons; neuronal excitability; striosomes; matrix; basal ganglia
Online: 31 May 2020 (18:20:17 CEST)
Huntington's disease (HD) is an inherited neurodegenerative disorder that usually starts during midlife with progressive alterations of motor and cognitive functions. The disease is caused by a CAG repeat expansion within the huntingtin gene leading to severe striatal neurodegeneration. Recent studies conducted on pre-HD children highlight early striatal developmental alterations starting as soon as 6 years old, the earliest age assessed. These findings, in line with data from mouse models of HD, raise the question of when during development do the first disease-related striatal alterations emerge or whether they contribute to the later appearance of the neurodegenerative features of the disease. In this review we will describe the different stages of striatal network development and then discuss recent evidence for its alterations in rodent models of the disease. We argue that a better understanding of the striatum’s development should help in assessing aberrant neurodevelopmental processes linked to the HD mutation.
ARTICLE | doi:10.20944/preprints202002.0250.v1
Subject: Life Sciences, Other Keywords: microRNAs; exosomes; astrocytes; hippocampal neurons; dendritic complexity
Online: 17 February 2020 (15:53:24 CET)
In the last decades, it has been established that astrocytes play key roles in the regulation of neuronal morphology. However, the contribution of astrocyte-derived small extracellular vesicles (sEVs) to morphological differentiation of neurons has only recently been addressed. Here, we showed that cultured astrocytes expressing a GFP tagged version of the stress-regulated astrocytic enzyme Aldolase C (Aldo C-GFP) release small extracellular vesicles (sEVs) which are transferred into cultured hippocampal neurons. Surprisingly, Aldo C-GFP-containing sEVs (Aldo C-GFP sEVs) displayed an exacerbated capacity to reduce the dendritic complexity in developing hippocampal neurons compared to sEVs derived from control (i.e. GFP-expressing) astrocytes. Using bioinformatics and biochemical tools, we found that the total content of overexpressed Aldo C-GFP correlates with an increased content of endogenous miRNA-26a-5p in both total astrocyte homogenates and sEVs. Notably, neurons magnetofected with a nucleotide sequence that mimics endogenous miRNA-26a-5p (mimic 26a-5p) not only decreased the levels of neuronal proteins associated to morphogenesis regulation and also reproduced morphological changes induced by Aldo-C-GFP sEVs. Furthermore, neurons magnetofected with a sequence targeting miRNA-26a-5p (antago 26a-5p) were largely resistant to Aldo C-GFP sEVs. Our results support a novel and complex level of astrocyte-to-neuron communication mediated by astrocyte-derived sEVs and the activity of their miRNA content.
Subject: Life Sciences, Cell & Developmental Biology Keywords: Parkinson's disease; development; dopamine neurons; substantial migration
Online: 22 December 2019 (13:16:16 CET)
Parkinson’s disease (PD) is a slowly progressing neurodegenerative disorder that is coupled to both widespread protein aggregation and to loss of substantia nigra dopamine (DA) neurons, resulting in a wide variety of motor and non-motor signs and symptoms. Recent findings suggest that the PD process is triggered several years before there is sufficient degeneration of DA neurons to cause onset of overt motor symptoms. According to this concept, the number of DA neurons present in the substantia nigra at birth could influence the time from the molecular triggering event until the clinical diagnosis with lower number of neurons at birth increasing the risk to develop the disease. Conversely, the risk for diagnosis would be reduced if the number of DA neurons is high at birth. In this commentary, we discuss the genetic and epigenetic factors that might influence the number of nigral DA neurons that each individual is born with and how these may be linked to PD risk.
REVIEW | doi:10.20944/preprints201907.0245.v1
Subject: Materials Science, Nanotechnology Keywords: carbon nanotubes; graphene; nanomaterials; nervous tissue; regeneration; neurons
Online: 23 July 2019 (03:54:21 CEST)
Nanomedicine has allowed for emerging advances in imaging, diagnostics and therapeutics. Regenerative Medicine has taken advantage of a number of nanomaterials for reparation of diseased or damaged tissues in the nervous system involved in memory, cognition and movement. Electrical, thermal, mechanical and biocompatibility aspects of carbon-based nanomaterials (nanotubes, graphene, fullerenes and their derivatives) make them suitable candidates to drive nerve tissue repair and stimulation. This review article focuses on recent advances on the use of carbon nanotube (CNT)-based technologies on nerve tissue engineering; outlining how neurons interact with the nanomaterials interface for promoting neuronal differentiation, growth and network reconstruction for their possible use in therapies of neurodegenerative pathologies and spinal cord injuries.
ARTICLE | doi:10.20944/preprints201810.0670.v1
Subject: Behavioral Sciences, Behavioral Neuroscience Keywords: granule cell neurons; electrophysiology; GluN; CaMKII; choline acetyltransferase
Online: 29 October 2018 (10:26:42 CET)
The present study examined differences in operant responses in adult male and female rats during distinct phases of addiction. Males and females demonstrated escalation in methamphetamine (0.05 mg/kg, i.v.) intake with females showing enhanced latency to escalate, and bingeing. Following protracted abstinence, females show reduced responses during extinction, and have greater latency to extinguish compared with males, indicating reduced craving. Females demonstrated lower context-driven reinstatement compared to males, indicating that females have less motivational significance to the context associated with methamphetamine. Whole-cell patch-clamp recordings on dentate gyrus (DG) granule cell neurons (GCNs) were performed in acute brain slices from controls and methamphetamine experienced male and female rats and neuronal excitability were evaluated from GCNs. Reinstatement of methamphetamine seeking reduced spiking in males, and increased spiking in females compared to controls, demonstrating distinct neuroadaptations in intrinsic excitability of GCNs in males and females. Reduced excitability of GCNs in males were associated with enhanced levels of neural progenitor cells, expression of plasticity-related proteins including CaMKII and choline acetyltransferase in the DG. Enhanced excitability in females were associated with increased GluN2A/2B ratio, indicating changes in postsynaptic GluN subunit composition in the DG. Altered intrinsic excitability of GCNs were associated with reduced mossy fiber terminals in the hilus and pyramidal projections, demonstrating compromised neuroplasticity in the DG in both sexes. The alterations in excitability, plasticity-related proteins and mossy fiber density were correlated with enhanced activation of microglial cells in the hilus, indicating neuroimmune responses in both sexes. Together, the present results indicate sexually dimorphic adaptive biochemical changes in excitatory neurotransmitter systems in the DG and highlight the importance of including sex as a biological variable in exploring neuroplasticity and neuroimmune changes that predict enhanced relapse to methamphetamine-seeking behaviors.
REVIEW | doi:10.20944/preprints202102.0478.v2
Subject: Keywords: epilepsy; computational model; seizures; single neurons level; networks; whole brain
Online: 16 June 2021 (12:14:49 CEST)
Dynamical system tools offer a complementary approach to detailed biophysical seizure modeling, with a high potential for clinical applications. This review describes the theoretical framework that provides a basis for theorizing certain properties of seizures and for their classification according to their dynamical properties at onset and offset. We describe various modeling approaches spanning different scales, from single neurons to large-scale networks. This narrative review provides an accessible overview of this field, including non-exhaustive examples of key recent works.
REVIEW | doi:10.20944/preprints202208.0263.v1
Subject: Life Sciences, Molecular Biology Keywords: Neural stem cells; Reprogramming; Neurons; MicroRNA; Somatic cells; Trans-Differentiation; miRNA
Online: 15 August 2022 (12:00:33 CEST)
Brain stem cells (neural stem cells or NSCs) and neurons of a chosen kind reprogramming is a potential technique for cell therapy. It is possible to reprogram non-neuronal cells, for example, by using a predetermined group of factors, nuclear transfer, and the induced transcriptional factors (TFs) expression in a related lineage of cells, and non-coding microRNAs (miRNAs). Researchers have additionally been attempting to improve reprogramming methods, whether it is by employing unique sets of biomolecules and particular TFs or by delivering relevant miRNA and Biomolecules. The technique of miRNA mediated is intriguing for its capability to quickly create a range of biologically desirable cell types for therapy from different lineages of cells. Current findings have made significant advancements towards changing the somatic cells to diverse particular neuronal subgroups with greater efficiency, using reprogramming of miRNA-mediated neural cells, despite the fact that the precise processes need to be discovered. To further understand how miRNAs might direct somatic cells to become neural, we need to look at the latest research on their function in neural reprogramming over the differentiated cells. Recent findings on the role of miRNAs in the initiation of cell reprogramming and the determination of the neuronal subtype's destiny are the primary focus of this comprehensive overview. Furthermore, we cover the far more latest results concerning certain miRNAs' activity in controlling different phases of neuronal differentiation, which contributes in comprehending the interaction network of miRNAs and their receptors.
REVIEW | doi:10.20944/preprints202204.0055.v1
Subject: Life Sciences, Molecular Biology Keywords: cell; biology; aging; medicine; transcription; activity; neurons; brain; immune system; muscle
Online: 7 April 2022 (04:24:23 CEST)
In several mammalian species including humans, complex stimulation patterns such as cognitive challenge and physical exercise lead to improvements in organ function, organism health and performance, as well as possibly longer lifespans. The hypothesis is presented here that activity-dependent transcriptional programs, induced by these environmental stimuli, temporarily and lightly de-differentiate somatic cells such as neurons and muscle cells into a state that resembles functionally younger cells to allow cellular remodeling and adaptation of the organism to environmental change. This cellular adaptation program targets several process classes that are heavily implicated in aging, such as mitochondrial metabolism, cell-cell communication, intracellular signaling and epigenetic information processing and leads to functional improvements in these areas. I reverse engineer these activity-dependent gene programs, identify critical molecular nexus points such as CREB, MEF2 and cFos and speculate as to how one might leverage them to prevent and attenuate human aging-related decline of body function, enhance human performance and restore more youthful levels of function and morphology. The findings presented here can serve as a basis for the study and development of effective longevity efforts as the underlying gene programs could be used as markers for treatment success and as targets for therapy development.
REVIEW | doi:10.20944/preprints202006.0203.v2
Subject: Life Sciences, Other Keywords: SH-SY5Y-derived neurons; TAU sorting; neuronal identity; tauopathy; Alzheimer’s disease
Online: 23 December 2020 (10:30:47 CET)
The microtubule-associated protein TAU is sorted into the axon in healthy brain neurons. Somatodendritic missorting of TAU is a pathological hallmark of many neurodegenerative diseases called tauopathies, including Alzheimer’s Disease (AD). Cause, consequence, and (patho)physiological mechanisms of TAU sorting and missorting are understudied, in part also due to the lack of readily available human neuronal model systems. The human neuroblastoma cell line SH-SY5Y is widely used for studying TAU physiology and TAU-related pathology in AD and related tauopathies. SH-SY5Y cells can be differentiated into neuron-like cells (SH-SY5Y-derived neurons) using various substances. This review evaluates whether SH-SY5Y-derived neurons are a suitable model for i) investigating intracellular TAU sorting in general, and ii) with respect to neuron subtype-specific TAU vulnerability. I) SH-SY5Y-derived neurons show pronounced axodendritic polarity, high levels of axonally localized TAU protein, expression of all six major human brain isoforms, and TAU phosphorylation similar to the human brain. As proliferative cells, SH-SY5Y cells are readily accessible for genetic engineering, stable transgene integration and leading-edge genome editing are valuable and promising tools for TAU-related studies. II) Depending on the used differentiation procedure, SH-SY5Y-derived neurons resemble cells of distinct subcortical nuclei, i.e. the Locus coeruleus (LC), Nucleus basalis (NB) and Substantia nigra (SN), all of which early affected in many tauopathies. This allows to analyse neuron-specific TAU isoform expression and intracellular localization, also in the context of vulnerability to TAU pathology. Limitations are e.g. the lack of mimicking age-related tauopathy risk factors and the difficulty to define the exact neuronal subtype of SH-SY5Y-derived neurons. In brief, this review discusses the suitability of SH-SY5Y-derived neurons for investigating TAU (mis)sorting mechanisms and neuron-specific TAU vulnerability in disease paradigms.
REVIEW | doi:10.20944/preprints201911.0031.v1
Subject: Life Sciences, Molecular Biology Keywords: lncRNA; translation; transcription; splicing; brain; cerebral cortex; neurogenesis; synaptic plasticity; neurons
Online: 4 November 2019 (03:06:01 CET)
Mammalian genomes encode tens of thousands of long-noncoding RNAs (lncRNAs), which are capable of interactions with DNA, RNA and protein molecules, thereby enabling a variety of transcriptional and post-transcriptional regulatory activities. Strikingly, about 40% of lncRNAs are expressed specifically in the brain in precisely regulated temporal and spatial expression patterns. In stark contrast to the highly conserved repertoire of protein-coding genes, thousands of new lncRNAs have appeared during primate nervous system evolution with hundreds of human-specific lncRNAs. Their evolvable nature and the myriad of potential functions make lncRNAs ideal candidates for drivers of human brain evolution. The human brain displays the largest relative volume of any animal species and the most remarkable cognitive abilities. In addition to brain size, structural reorganization and adaptive changes represent crucial hallmarks of human brain evolution. LncRNAs are increasingly reported to be involved in neurodevelopmental processes including proliferation, neurite outgrowth and synaptogenesis, as well as in neuroplasticity, suggested to underlie human brain evolution. Hence, evolutionary human brain adaptations are proposed to be essentially driven by lncRNAs, which will be discussed in this review.
REVIEW | doi:10.20944/preprints201811.0592.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: caspase-3; cell death; apoptosis; cell proliferation; neurons; glia; cerebellum; development
Online: 26 November 2018 (11:48:00 CET)
Caspase-3, onto which there is a convergence of the intrinsic and extrinsic apoptotic pathways, is the main executioner of apoptosis. We here review the current literature on the intervention of the protease in the execution of naturally occurring neuronal death (NOND) during cerebellar development. We will consider data on the most common altricial species (rat, mouse and rabbit), as well as humans. Among the different types of neurons and glia in cerebellum, there is ample evidence for an intervention of caspase-3 in the regulation of NOND of the post-mitotic cerebellar granule cells (CGCs) and Purkinje neurons as a consequence of failure to establish proper synaptic contacts with target (secondary cell death). It seems possible that also the GABAergic interneurons undergo a similar type of secondary cell death, but the intervention of caspase-3 in this case still remains to be clarified in full. Remarkably, CGCs also undergo primary cell death at the precursor/pre-migratory stage of differentiation, in this case without the intervention of caspase-3. Glial cells as well undergo a process of regulated cell death, but it seems possible that expression of caspase-3, at least in the Bergmann glia, is related to differentiation rather than death.
REVIEW | doi:10.20944/preprints202106.0241.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Neurons; Astrocytes; Neurodegeneration; Neurodevelopmental diseases; Memory; Learning; Inflammation; Oxidative Stress; sleep disorders
Online: 9 June 2021 (07:36:28 CEST)
Inside Central Nervous System (CNS) appears neurons and glia cells. There are more glial cells than neurons and have more functions than neurons. Glia name represents different kind of cells, ones from neural origin (astrocytes, radial glia, and oligodendroglia), and others from blood monocytes (microglia). During ontogeny, neurons appear first (rat fetal 15th) and after astrocytes (rat fetal 21th) indicating a bigger importance function in the CNS. Also, during the phylogeny, reptiles have less astrocytes compared to neurons and in humans, astrocytes are double in number than neurons. This data, perhaps means that astrocytes are more special cells and work in memory and learning? Astrocytes have an important role in different mechanisms protecting CNS across the production of antioxidant and anti-inflammatory proteins, cleaning extracellular medium and helping neurons to communicate with each other correctly. Inflammatory mediators production are important to prevent changes in normal physiology. But, excessive or continue production leads to many diseases, such as Alzheimer's disease (AD), Sclerosis Lateral Amyotrophic (ELA), Multiple sclerosis (MS), and neurodevelopment diseases, like Bipolar disorder, Schizophrenia, and Autism's symptomatology. Different drugs and thecniques can reverse oxidative stress and/or inflammatory excess. This review is intended to serve as an approximation to the field.
ARTICLE | doi:10.20944/preprints202008.0643.v1
Subject: Keywords: ulcerative colitis; inflammatory bowel disease; immunotherapy; Bin1 monoclonal antibody; enteric neurons; microbiome; colon
Online: 28 August 2020 (11:45:28 CEST)
Ulcerative colitis (UC) is a common chronic disease of the large intestine. Current anti-inflammatory drugs prescribed to treat this disease have limited utility due to significant side-effects. Thus, immunotherapies for UC treatment are still sought. In the DSS mouse model of UC, we recently demonstrated that systemic administration of the Bin1 monoclonal antibody 99D (Bin1 mAb) developed in our laboratory was sufficient to reinforce intestinal barrier function and preserve an intact colonic mucosa, compared to control subjects which displayed severe mucosal lesions, high-level neutrophil and lymphocyte infiltration of mucosal and submucosal areas, and loss of crypts. Here we report effects of Bin1 mAb on colonic neurons and the gut microbiome that correlate with the benefits of treatment. In the DSS model, we found that induction of UC was associated with disintegration of enteric neurons and elevated levels of glial cells, which translocated to the muscularis at distinct sites. Further, we characterized an altered gut microbiome in DSS treated mice associated with pathogenic proinflammatory characters. Both of these features of UC induction were normalized by Bin1 mAb treatment. With regard to microbiome changes, we observed in particular that Firmicutes were eliminated by UC induction and that Bin1 mAb treatment restored this phylum including the genus Lactobacillus and Akkermansia as beneficial microorganisms. Overall, our findings suggest that the intestinal barrier function restored by Bin1 immunotherapy in the DSS model of UC is associated with a preservation of enteric neurons and an improvement in the gut microbiome, contributing overall to a healthy intestinal tract.
ARTICLE | doi:10.20944/preprints202108.0006.v1
Subject: Medicine & Pharmacology, Allergology Keywords: cultured neurons; insulin; glutamate; [Ca2+]i; mitochondrial potential; ATP; oxygen consumption rate; superoxide; ROS
Online: 2 August 2021 (09:10:44 CEST)
Glutamate excitotoxicity is implicated in the pathogenesis of many disorders, including stroke, traumatic brain injury, and Alzheimer’s disease, for which central insulin resistance is a comorbid condition. Massive glutamate release primarily through ionotropic N-methyl-D-aspartate receptors (NMDARs) causes a sustained rise in [Ca2+]i, followed by mitochondrial depolarization and an increase in intracellular O2• (superoxide) production. Recently, we found that insulin protected neurons against excitotoxicity by diminishing the delayed calcium deregulation (DCD), However, a role of insulin in superoxide production in excitotoxicity still needs to be clarified. The present study is aimed to investigate the effects of insulin on glutamate-evoked superoxide generation and DCD using the fluorescent indicators dihydroethidium, MitoSOX Red, and Fura-FF in rats cultured cortical neurons. We found that insulin significantly diminished both the intracellular and mitochondrial superoxide production in neurons exposed to glutamate and there was a strong linear correlation between [Ca2+]i and intracellular superoxide. MK 801, an inhibitor of NMDAR-gated Ca2+ influx, completely abrogated the glutamate effects in both the presence and absence of insulin. In experiments on sister cultures, insulin diminishes neuronal death. Thus, collectively, data obtained suggest that insulin diminishes glutamate-induced superoxide production in neurons via fall of [Ca2+]i increased and thereby improves viability of neurons
Subject: Keywords: paraoxonases; oxidative stress; Alzheimer’s disease; brain; Tg2576 mice; astrocytes; hippocampus; amyloid-β; microglia; neurons
Online: 18 December 2020 (11:53:45 CET)
Background: Brain oxidative lipid damage and inflammation are common in neurodegenerative diseases such as Alzheimer’s disease (AD). Paraoxonase-1 and 3 (PON1 and PON3) protein expression have been described in tissues with no PON1 and PON3 gene expression. In the present study, we aimed to examine differences in PON1 and PON3 protein expression in the brain of a mouse model of AD. Methods: We used peroxidase-based and fluorescence-based immunohistochemistry in 5 brain regions (olfactory bulb, forebrain, posterior midbrain, hindbrain and cerebellum) of transgenic (Tg2576) mice with the Swedish mutation (KM670/671NL) responsible for a familial form of AD and corresponding wild-type mice. Results: We found intense PON1 and PON3 positive staining in star-shaped cells surrounding Aβ plaques in all Tg2576 mouse brain regions studied. Although we could not co-localize PON1 and PON3 with astrocytes, brain star-shaped cells, we found some co-localization of PON3 with microglia. Conclusions: These results suggest that 1) PON1 and PON3 cross the blood-brain barrier in discoidal HDLs and are transferred to specific brain cell types, and 2) PON1 and PON3 play an important role in preventing oxidative stress and lipid peroxidation in particular cell types, likely astrocytes and microglia, in AD pathology, and potentially in other neurodegenerative diseases
ARTICLE | doi:10.20944/preprints202008.0091.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: induced pluripotent stem cells; disease modelling; neuronal differentiation; cholinergic neurons; Alzheimer’s disease; frontotemporal dementia
Online: 4 August 2020 (11:17:44 CEST)
The study of neurodegenerative diseases using pluripotent stem cells requires new methods to assess neurodevelopment and neurodegeneration of specific neuronal subtypes. The cholinergic system, characterized by its use of the neurotransmitter acetylcholine, is one of the first to degenerate in Alzheimer’s disease and is also affected in frontotemporal dementia. We developed a differentiation protocol to generate basal forebrain cholinergic neurons (BFCNs) from induced pluripotent stem cells (iPSCs) aided by the use of small molecule inhibitors and growth factors. Ten iPSC lines were successfully differentiated into BFCNs using this protocol. The neuronal cultures were characterised through RNA and protein expression, and functional analysis of neurons was confirmed by whole-cell patch clamp. We have developed a reliable protocol using only small molecule inhibitors and growth factors, while avoiding transfection or cell sorting methods, to achieve a BFCN culture that expresses the characteristic markers of cholinergic neurons.
ARTICLE | doi:10.20944/preprints202205.0256.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: Extracellular matrices; Macromolecular crowding; human iPSC derived astrocytes; human iPSC derived dopaminergic neurons; drug testing
Online: 19 May 2022 (08:50:28 CEST)
The neuroglial extracellular matrix (ECM) provides critical support and physiological cues for the proper growth, differentiation, and function of neuronal cells in the brain. However, in most in vitro settings that study neural physiology, cells are grown as monolayers on stiff surfaces that maximize adhesion and proliferation, and therefore lack the physiological cues that ECM in native neuronal tissues provides. Macromolecular crowding (MMC) is a biophysical phenomenon based on the principle of excluded volume that can be harnessed to induce native ECM deposition by cells in culture. Here, we show that MMC using two species of Ficoll with vitamin C supplementation significantly boosts deposition of relevant brain ECM by cultured human astrocytes. Dopaminergic neurons co-cultured on this astrocyte-ECM bed prepared under MMC treatment showed longer and denser neuronal extensions, a higher number of pre ad post synaptic contacts, and increased physiological activity as evidenced by higher frequency calcium oscillation, compared to standard co-culture conditions. When the pharmacological activity of various compounds was tested on MMC-treated co-cultures, their responses were enhanced, and for apomorphine, a D2-receptor agonist, it was inverted in comparison to control cell culture conditions, thus emulating responses observed in in vivo settings. These results indicate that macromolecular crowding can harness the ECM-building potential of human astrocytes in vitro forming an ultra-flat 3D microenvironment that makes neural cultures more physiological and pharmacological relevant.
ARTICLE | doi:10.20944/preprints202111.0126.v1
Subject: Behavioral Sciences, Behavioral Neuroscience Keywords: consciousness; catecholaminergic neurons; substantia nigra pars compacta; locus coeruleus; ferritin; electron transport; voluntary action selection
Online: 8 November 2021 (09:33:34 CET)
A newly-discovered physical mechanism involving electron tunneling in layers of the protein ferritin that are found in catecholaminergic neurons (catecholaminergic neuron electron transport or CNET), is hypothesized to support communication between neurons. Recent tests further confirm that these ferritin layers can also perform a switching function (in addition to providing an electron tunneling mechanism) that could be associated with action selection in those neurons, consistent with earlier predictions based on CNET. While further testing would be needed to confirm the hypothesis that CNET allows groups of neurons to communicate and act as a switch for selecting one of the neurons in the group to assist in reaching action potential, this paper explains how that hypothesized behavior would be consistent with Integrated Information Theory (IIT), one of a number of consciousness theories (CTs). While the sheer number of CTs suggest that any one of them is not sufficient to explain consciousness, this paper demonstrates that CNET can provide a physical substrate that is consistent with IIT and which can also be applied to other CTs, such as to conform them into a single explanation of consciousness.
HYPOTHESIS | doi:10.20944/preprints202109.0360.v1
Subject: Keywords: action potential; skeletal muscle cells; synaptic connection of neurons; space curved manifolds; time curved manifolds
Online: 21 September 2021 (12:04:03 CEST)
Abstract Although we know something about single cell neuromuscular junction, It is still mysterious how multiple skeletal muscle cells coordinate to complete the intricate spatial curve movement. Here I propose a hypothesis that skeletal muscle cell populations with action potentials are alligned according to a curved manifolds on space(a curved shape on space) and the skeletal muscle also moves according to this corresponding shape(manifolds) when an specific motor nerve impulses are transmitted. the action potential of motor nerve fibers has the characteristics of time curve manifold and this time manifold curve of motor nerve fibers come from visual cortex in which a spatial geometric manifolds are formed within the synaptic connection of neurons. This spatial geometric manifolds of the synaptic connection of neurons orginate from spatial geometric manifolds in outside nature that are transmitted to brain through the cone cells and ganglion cells of the retina.Further,the essence of life is that life is an object that can move autonomously and the essence of life's autonomous movement is the movement of proteins. theoretically, due to the infinite diversity of geometric manifold shapes in nature, the arrangement and combination of 20 amino acids should have infinite diversity, and the geometric manifold formed by protein three-dimensional spatial structure should also have infinite diversity.
ARTICLE | doi:10.20944/preprints202011.0360.v1
Subject: Life Sciences, Biochemistry Keywords: Riboflavin transporter deficiency; motor neurons; mitochondria; energy metabolism; electron microscopy; antioxidants; SOD2; oxidative stress; neurodegeneration
Online: 12 November 2020 (18:14:17 CET)
Riboflavin transporter deficiency (RTD) is a childhood-onset neurodegenerative disorder characterized by sensorineural deafness and motor neuron degeneration. Since riboflavin plays key functions in biological oxidation-reduction reactions, energy metabolism pathways involving flavoproteins are affected in RTD. We recently generated iPSC lines from affected individuals as an in vitro model of the disease and documented mitochondrial impairment in these cells dramatically impacting cell redox status. In the present work, we extend our study to motor neurons (MNs), i.e., the cell type mostly affected in patients with RTD. Altered intracellular distribution of mitochondria was detected by confocal microscopic analysis, following immunofluorescence for superoxide dismutase 2 (SOD2), as a dual mitochondrial and antioxidant marker, and βIII Tubulin, as neuronal marker. We demonstrate significantly lower SOD2 levels in RTD MNs, as compared to their healthy counterparts. Mitochondrial ultrastructural abnormalities were also assessed by Focused Ion Beam/Scanning Electron Microscopy. Moreover, we investigated the effects of combination treatment using riboflavin and N-acetylcysteine, which is a widely employed antioxidant. Overall, our findings further support the potential of patient specific RTD models, and provide evidence of mitochondrial alterations in RTD-related iPSC-derived MNs, emphasizing oxidative stress involvement in this rare disease. We also provide new clues for possible therapeutic strategies, aimed at correcting mitochondrial defects, based on the use of antioxidants.
ARTICLE | doi:10.20944/preprints202108.0225.v1
Subject: Biology, Physiology Keywords: microglia; gut-brain axis; antibiotics; glutamatergic synapses; hippocampus; patch clamp; hippocampal slices.; microbiota; neurons; glutamatergic trasmission
Online: 10 August 2021 (10:04:00 CEST)
‘Dysbiosis’ of the adult gut microbiota, in response to challenges such as infection, altered diet, stress, and antibiotics treatment has been recently linked to pathological alteration of brain func-tion and behavior. Moreover, gut microbiota composition constantly controls microglia matura-tion as revealed by morphological observations and gene expression analysis. However, it is un-clear whether gut microbiota influences microglia functional properties and crosstalk with neu-rons, known to shape and modulate synaptic development and function. Here, we investigated how antibiotic mediated alteration of the gut microbiota influences microglial and neuronal functions in adult mice hippocampus. Hippocampal microglia from adult mice treated with oral antibiotics exhibited increased microglia density, altered basal patrolling activity, and impaired process rearrangement in response to damage. Patch clamp recordings at CA3-CA1 synapses revealed that antibiotics treatment alters neuronal functions, reducing spontaneous postsynaptic glutamatergic currents and decreasing synaptic connectivity, without reducing dendritic spines density. The effect of dysbiosis on neuronal functions are mediated by microglia-neuron cross-talk through the CX3CL1-CX3CR1 axis, as antibiotics treatment of CX3CR1 deficient mice, mod-ulates microglia density and processes rearrangement leaving unaltered synaptic function. To-gether, our findings show that the antibiotics alteration of gut microbiota impairs synaptic effi-cacy, probably through CX3CL1-CX3CR1 signaling supporting microglia as a major player in in the gut-brain axis, and in particular in the gut microbiota-to-neuron communication pathway.
REVIEW | doi:10.20944/preprints202106.0448.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Parkinson’s disease; abnormal involuntary movements; dopaminergic signaling; basal ganglia; spiny projection neurons; neurotransmission; deep brain stimulation
Online: 16 June 2021 (14:17:30 CEST)
Levodopa remains the primary drug for controlling motor symptoms in Parkinson's disease through the whole course, but over time complications develop in the form of dyskinesias, which gradually become more frequent and severe. These abnormal, involuntary, hyperkinetic movements are mostly characteristic of the ON phase and reflect an excess of exogenous levodopa. They may also occur during OFF phase, or in both phases. Over the past 10 years, the issue of levodopa-induced dyskinesia has been the subject of research into both the substrate of this pathology and potential remedial strategies. The purpose of the present study was to review the results of recent research on the background and treatment of dyskinesia. To this end, databases were reviewed using a search strategy that included both relevant keywords related to the topic and appropriate filters to limit results to English-language literature published since 2010. Based on the selected papers, the current state of knowledge on morphological, functional, genetic, and clinical features of levodopa-induced dyskinesia, as well as pharmacological, genetic treatment and other therapies such as deep brain stimulation are described.
REVIEW | doi:10.20944/preprints201810.0385.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: Parkinson’s disease; cell death; dopaminergic neurons; Wnt/β-catenin signaling; glia-neuron crosstalk; neurodegeneration; neuroprotection; neurorepair
Online: 17 October 2018 (12:28:35 CEST)
Wingless-type MMTV integration site (Wnt) signaling is one of the most critical pathways in developing and adult tissues. In the brain, Wnt signaling contributes to different neurodevelopmental aspects ranging from differentiation, axonal extension, synapse formation, neurogenesis and neuroprotection. Canonical Wnt signaling is mediated mainly by the multifunctional β-catenin protein which is a potent co-activator of transcription factors such as Lymphoid Enhancer Factor (LEF) and T Cell Factor (TCF). Accumulating evidence points to dysregulation of Wnt/β-catenin signaling in major neurodegenerative disorders. Here I focus on a “Wnt/β-catenin-glial connection” in Parkinson’s disease (PD), the most common movement disorder characterized by the selective death of midbrain dopaminergic (mDAergic) neuronal cell bodies in the subtantia nigra pars compacta (SNpc) and gliosis. I will summarize the work of the last decade documenting that Wnt/β-catenin signaling in partnership with glial cells is critically involved in each step and at every levels in the regulation of nigrostriatal DAergic neuronal health, protection and regeneration in the MPTP mouse model of PD, focusing on Wnt/β-catenin signaling to boost a full neurorestorative program in PD.
Subject: Medicine & Pharmacology, Allergology Keywords: histamine; histamine H1 receptor; histamine H4 receptor; itch; TRPV1; TRPA1; dorsal root ganglion neurons (DRG); Ca2+-imaging
Online: 15 July 2021 (10:12:01 CEST)
Two histamine receptor subtypes (HR), namely H1R and H4R, as key components, are involved in the transmission of histamine-induced itch. Although exact downstream signaling mechanisms are still elusive, transient receptor potential (TRP) ion channels play important roles in the sensation of histaminergic and non-histaminergic itch. Aim of this study was to investigate the involvement of TRPV1 and TRPA1 channels in the transmission of histaminergic itch. The potential of TRPV1 and TRPA1 inhibitors to modulate H1R- and H4R-induced signal transmission was tested in a scratching assay in mice in vivo and in vitro via Ca2+ imaging of murine sensory dorsal root ganglia (DRG) neurons. The TRPV1 inhibition led to a reduction of H1R- and H4R- induced itch and reduced Ca2+ influx into the neurons. The TRPA1 inhibitor reduced H4R-induced itch and both H1R- and H4R-induced Ca2+ influx. In conclusion, these results indicate that both channels, TRPV1 and TRPA1 are involved in the transmission of histamine-induced pruritus.
REVIEW | doi:10.20944/preprints202012.0244.v1
Subject: Biology, Anatomy & Morphology Keywords: CAMs; Classical Cadherins; Nectins; Neocortical Development; Radial Glia Cells; Neurons; Neuronal Migration; Axon Targeting; Synaptogenesis; Autism/Neurodevelopmental disorders
Online: 10 December 2020 (10:23:42 CET)
The neocortex is an exquisitely organized structure achieved through complex cellular processes from the generation of neural cells to their integration into cortical circuits after complex migration processes. During this long journey, neural cells need to stablish and release adhesive interactions through cell surface receptors known as cell adhesion molecules (CAMs). Several types of CAMs have been described regulating different aspects of neurodevelopment. Whereas some of them mediate interactions with the extracellular matrix, others allow contacts with additional cells. In this review, we will focus on the role of two important families of cell-cell adhesion molecules (C-CAMs), classical cadherins and nectins, as well as in their effectors, in the control of fundamental processes related with corticogenesis, with especial attention in the cooperative actions among the two families of C-CAMs.
ARTICLE | doi:10.20944/preprints201904.0246.v2
Subject: Medicine & Pharmacology, Behavioral Neuroscience Keywords: Oxytocin, Oxytocin Receptor, Autism, Nepsys Scale, MAST Immune System Disease, Dendritic Spines, Magnocellular Neurons, Desensitization, Labor, Down Regulation
Online: 23 April 2019 (11:12:19 CEST)
This paper develops mathematical models examining possible roles of oxytocin and oxytocin receptors in the development of autism. This is done by demonstrating that mathematical operations on normalized data from the Stanford study (K.J. Parker, 2016), which establishes a correspondence between severity of autism in children and their oxytocin blood levels, generates a graph that is the same as the graph of mathematical operations on a normalized theoretical model for the severity of autism. This procedure establishes the validity of the theoretical model and the significance of oxytocin receptors in autism. A steady-state model follows, explaining the constant baseline concentrations of oxytocin observed in the cerebral spinal fluid and blood in terms of the neuromodulation by oxytocin of oxytocin receptors on the magnocellular neurons that produce oxytocin in nuclei in the hypothalamus. The implications of these models for possible roles of oxytocin and oxytocin receptors in autism is considered for several unrelated conditions that may be associated with autism. These are: oxytocin receptor desensitization and down-regulation as factors during labor in offspring autism development; reductions in the oxytocin receptor numbers in the fixed oxytocin receptor expression that occurs before birth; MAST Immune System disease; and the excess number of dendritic spines from lack of pruning observed in brains of autistic people. Research into the feasibility of generating magnocellular neurons and other neurons from adult stem cells is suggested as a way of doing invitro studies of oxytocin and oxytocin receptors to assess the validity of theories presented in this paper.
REVIEW | doi:10.20944/preprints201801.0109.v1
Subject: Behavioral Sciences, Developmental Psychology Keywords: dyslexia; reading; magnocellular neurons; vision; hearing; phonology; sequencing; timing; temporal processing; transient; coloured filters; rhythm; music; omega 3s
Online: 12 January 2018 (07:15:33 CET)
Until the 1950s, developmental dyslexia was defined as a hereditary visual disability, selectively affecting reading without compromising oral or non-verbal reasoning skills. This changed radically after the development of the phonological theory of dyslexia; this not only ruled out any role for visual processing in its aetiology, but also cast doubt on the use of discrepancy between reading and reasoning skills as a criterion for diagnosing it. Here I argue that this theory is set at too high a cognitive level to be explanatory; we need to understand the pathophysiological visual and auditory mechanisms that cause children’s phonological problems. I discuss how the ‘magnocellular theory’ attempts to do this in terms of slowed and error prone temporal processing which leads to dyslexics’ defective visual and auditory sequencing when attempting to read. I attempt to deal with the criticisms of this theory and show how it leads to a number of successful ways of helping dyslexic children to overcome their reading difficulties.
REVIEW | doi:10.20944/preprints202105.0098.v1
Subject: Life Sciences, Virology Keywords: Campenot, neurons, superior cervical ganglia, dorsal root ganglia, virus, alphaherpesvirus, herpes simplex virus, pseudorabies virus, fluorescence microscopy, cryo electron tomography
Online: 6 May 2021 (15:08:12 CEST)
The development of compartmentalized neuron culture systems has been invaluable in the study of neuroinvasive viruses, including the alpha herpesviruses Herpes Simplex Virus 1 (HSV-1) and Pseudorabies Virus (PRV). This chapter provides updated protocols for assembling and culturing rodent embryonic superior cervical ganglion (SCG) and dorsal root ganglion (DRG) neurons in Campenot trichamber cultures. In addition, we provide several illustrative examples of the types of experiments that are enabled by Campenot cultures: 1. Using fluorescence microscopy to investigate axonal outgrowth/extension through the chambers, and alpha herpesvirus infection, intracellular trafficking, and cell-cell spread via axons. 2. Using correlative fluorescence microscopy and cryo electron tomography to investigate the ultrastructure of virus particles trafficking in axons.
ARTICLE | doi:10.20944/preprints201806.0092.v1
Subject: Life Sciences, Other Keywords: Neuroscience; basal ganglia; cortical layers; cerebellum; habenula; inhibition; predictions; dopamine; serotonin; acetylcholine; opioids; mirror neurons; place cells; language; imagery; working memory
Online: 7 June 2018 (06:02:29 CEST)
Understanding brain function is one of the most important open problems in science today. At present, there is no concrete theory for how the brain works. Here, a theory is presented that provides a detailed mechanistic biological account of the brain’s capacities. Brain function is managed by a response (R) process that is structurally similar to the immune response, and shows anatomical and molecular specificity. Different R process stages utilize different cortical layers, hippocampus fields, basal ganglia paths, GABAergic interneurons, cerebellum paths, and molecular agents such as dopamine, serotonin and opioids. We show how the R process supports hierarchical action sequences, language and thought. The theory is supported by a large body of experimental evidence in many modalities, and accounts for virtually all of the major facts known about the brain at the system level.