Relationship between Hypoxia and Hypercapnia Tolerance and Life Expectancy.

The review discusses the potential relationship between hypoxia resistance and longevity, the influence of carbon dioxide on the mechanisms of aging of the mammalian organism, and intermittent hypercapnic-hypoxic effects on the signaling pathways of aging mechanisms. In the article, we focused on the potential mechanisms of the gero-protective efficacy of carbon dioxide when combined with hypoxia. The review summarizes the possible influence of intermittent hypoxia and hypercapnia on aging processes in the nervous system. We considered the perspective variants of the application of hypercapnic-hypoxic influences for achieving active longevity and the prospects for the possibilities of developing hypercapnic-hypoxic training methods.

The Role of microRNAs in Epigenetic Regulation of Signaling Pathways in Neurological Pathologies.

In recent times, there has been a significant increase in researchers' interest in the functions of microRNAs and the role of these molecules in the pathogenesis of many multifactorial diseases. This is related to the diagnostic and prognostic potential of microRNA expression levels as well as the prospects of using it in personalized targeted therapy. This review of the literature analyzes existing scientific data on the involvement of microRNAs in the molecular and cellular mechanisms underlying the development of pathologies such as Alzheimer's disease, cerebral ischemia and reperfusion injury, and dysfunction of the blood-brain barrier.

Novel Approaches to the Establishment of Local Microenvironment from Resorbable Biomaterials in the Brain In Vitro Models.

The development of brain in vitro models requires the application of novel biocompatible materials and biopolymers as scaffolds for controllable and effective cell growth and functioning. The "ideal" brain in vitro model should demonstrate the principal features of brain plasticity like synaptic transmission and remodeling, neurogenesis and angiogenesis, and changes in the metabolism associated with the establishment of new intercellular connections. Therefore, the extracellular scaffolds that are helpful in the establishment and maintenance of local microenvironments supporting brain plasticity mechanisms are of critical importance. In this review, we will focus on some carbohydrate metabolites-lactate, pyruvate, oxaloacetate, malate-that greatly contribute to the regulation of cell-to-cell communications and metabolic plasticity of brain cells and on some resorbable biopolymers that may reproduce the local microenvironment enriched in particular cell metabolites.

Astrocyte Activation Markers.

Astrocytes are the most common type of glial cells that provide homeostasis and protection of the central nervous system. Important specific characteristic of astrocytes is manifestation of morphological heterogeneity, which is directly dependent on localization in a particular area of the brain. Astrocytes can integrate into neural networks and keep neurons active in various areas of the brain. Moreover, astrocytes express a variety of receptors, channels, and membrane transporters, which underlie their peculiar metabolic activity, and, hence, determine plasticity of the central nervous system during development and aging. Such complex structural and functional organization of astrocytes requires the use of modern methods for their identification and analysis. Considering the important fact that determining the most appropriate marker for polymorphic and multiple subgroups of astrocytes is of decisive importance for studying their multifunctionality, this review presents markers, modern imaging techniques, and identification of astrocytes, which comprise a valuable resource for studying structural and functional properties of astrocytes, as well as facilitate better understanding of the extent to which astrocytes contribute to neuronal activity.

Physiological and Pathological Remodeling of Cerebral Microvessels.

There is growing evidence that the remodeling of cerebral microvessels plays an important role in plastic changes in the brain associated with development, experience, learning, and memory consolidation. At the same time, abnormal neoangiogenesis, and deregulated regulation of microvascular regression, or pruning, could contribute to the pathogenesis of neurodevelopmental diseases, stroke, and neurodegeneration. Aberrant remodeling of microvesselsis associated with blood-brain barrier breakdown, development of neuroinflammation, inadequate microcirculation in active brain regions, and leads to the dysfunction of the neurovascular unit and progressive neurological deficits. In this review, we summarize current data on the mechanisms of blood vessel regression and pruning in brain plasticity and in Alzheimer's-type neurodegeneration. We discuss some novel approaches to modulating cerebral remodeling and preventing degeneration-coupled aberrant microvascular activity in chronic neurodegeneration.

Chronic optogenetic stimulation of Bergman glia leads to dysfunction of EAAT1 and Purkinje cell death, mimicking the events caused by expression of pathogenic ataxin-1.

Bergmann glia (BG) are highly specialized radial astrocytes of the cerebellar cortex, which play a key role in the uptake of synaptic glutamate via the excitatory amino acid transporter EAAT1. Multiple lines of evidence suggest that in cerebellar neurodegenerative diseases reactive BG has a negative impact on neuronal function and survival through compromised EAAT activity. A family of such diseases are those caused by expansion of CAG repeats in genes of the ataxin family, resulting in spinocerebellar ataxias (SCA). We investigated the contribution of BG to the pathogenesis of cerebellar neurodegeneration in a model of SCA1, which was induced by expression of a polyglutamine mutant of ataxin-1 (ATXN1[Q85]) in BG specifically. We compared the outcomes with a novel model where we triggered excitotoxicity by a chronic optogenetic activation of BG with channelrhodopsin-2 (ChR2). In both cases we detected evidence of reduced glutamate uptake manifested by prolongation of excitatory postsynaptic currents in Purkinje cells which is consistent with documented reduction of expression and/or function of EAAT1. In both models we detected astroglyosis and Purkinje cells atrophy. Finally, the same pattern was detected in a knock-in mouse which expresses a polyglutamine mutant ataxin-1 ATXN1[Q154] in a non-cell-selective manner. Our results suggest that ATXN1[Q85] and ChR2-induced insult targeted to BG closely mimics SCA1 pathology, where excessive glutamate signaling appears to be a common feature likely being an important contributor to cerebellar neurodegeneration.

Blood-Brain Barrier Breakdown in Stress and Neurodegeneration: Biochemical Mechanisms and New Models for Translational Research.

Blood-brain barrier (BBB) is a structural and functional element of the neurovascular unit (NVU), which includes cells of neuronal, glial, and endothelial nature. The main functions of NVU include maintenance of the control of metabolism and chemical homeostasis in the brain tissue, ensuring adequate blood flow in active regions, regulation of neuroplasticity processes, which is realized through intercellular interactions under normal conditions, under stress, in neurodegeneration, neuroinfection, and neurodevelopmental diseases. Current versions of the BBB and NVU models, static and dynamic, have significantly expanded research capabilities, but a number of issues remain unresolved, in particular, personification of the models for a patient. In addition, application of both static and dynamic models has an important problem associated with the difficulty in reproducing pathophysiological mechanisms responsible for the damage of the structural and functional integrity of the barrier in the diseases of the central nervous system. More knowledge on the cellular and molecular mechanisms of BBB and NVU damage in pathology is required to solve this problem. This review discusses current state of the cellular and molecular mechanisms that control BBB permeability, pathobiochemical mechanisms and manifestations of BBB breakdown in stress and neurodegenerative diseases, as well as the problems and prospects of creating in vitro BBB and NVU models for translational studies in neurology and neuropharmacology. Deciphering BBB (patho)physiology will open up new opportunities for further development in the related areas of medicine such as regenerative medicine, neuropharmacology, and neurorehabilitation.

Novel Approaches Used to Examine and Control Neurogenesis in Parkinson's Disease.

Neurogenesis is a key mechanism of brain development and plasticity, which is impaired in chronic neurodegeneration, including Parkinson's disease. The accumulation of aberrant α-synuclein is one of the features of PD. Being secreted, this protein produces a prominent neurotoxic effect, alters synaptic plasticity, deregulates intercellular communication, and supports the development of neuroinflammation, thereby providing propagation of pathological events leading to the establishment of a PD-specific phenotype. Multidirectional and ambiguous effects of α-synuclein on adult neurogenesis suggest that impaired neurogenesis should be considered as a target for the prevention of cell loss and restoration of neurological functions. Thus, stimulation of endogenous neurogenesis or cell-replacement therapy with stem cell-derived differentiated neurons raises new hopes for the development of effective and safe technologies for treating PD neurodegeneration. Given the rapid development of optogenetics, it is not surprising that this method has already been repeatedly tested in manipulating neurogenesis in vivo and in vitro via targeting stem or progenitor cells. However, niche astrocytes could also serve as promising candidates for controlling neuronal differentiation and improving the functional integration of newly formed neurons within the brain tissue. In this review, we mainly focus on current approaches to assess neurogenesis and prospects in the application of optogenetic protocols to restore the neurogenesis in Parkinson's disease.

NLRP3 Inflammasome Blocking as a Potential Treatment of Central Insulin Resistance in Early-Stage Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is a devastating neurodegenerative disorder. In recent years, attention of researchers has increasingly been focused on studying the role of brain insulin resistance (BIR) in the AD pathogenesis. Neuroinflammation makes a significant contribution to the BIR due to the activation of NLRP3 inflammasome. This study was devoted to the understanding of the potential therapeutic roles of the NLRP3 inflammasome in neurodegeneration occurring concomitant with BIR and its contribution to the progression of emotional disorders. METHODS: To test the impact of innate immune signaling on the changes induced by Aß1-42 injection, we analyzed animals carrying a genetic deletion of the Nlrp3 gene. Thus, we studied the role of NLRP3 inflammasomes in health and neurodegeneration in maintaining brain insulin signaling using behavioral, electrophysiological approaches, immunohistochemistry, ELISA and real-time PCR. RESULTS: We revealed that NLRP3 inflammasomes are required for insulin-dependent glucose transport in the brain and memory consolidation. Conclusions NLRP3 knockout protects mice against the development of BIR: Taken together, our data reveal the protective role of Nlrp3 deletion in the regulation of fear memory and the development of Aß-induced insulin resistance, providing a novel target for the clinical treatment of this disorder.

Blood-Brain Barrier and Neurovascular Unit In Vitro Models for Studying Mitochondria-Driven Molecular Mechanisms of Neurodegeneration.

Pathophysiology of chronic neurodegeneration is mainly based on complex mechanisms related to aberrant signal transduction, excitation/inhibition imbalance, excitotoxicity, synaptic dysfunction, oxidative stress, proteotoxicity and protein misfolding, local insulin resistance and metabolic dysfunction, excessive cell death, development of glia-supported neuroinflammation, and failure of neurogenesis. These mechanisms tightly associate with dramatic alterations in the structure and activity of the neurovascular unit (NVU) and the blood-brain barrier (BBB). NVU is an ensemble of brain cells (brain microvessel endothelial cells (BMECs), astrocytes, pericytes, neurons, and microglia) serving for the adjustment of cell-to-cell interactions, metabolic coupling, local microcirculation, and neuronal excitability to the actual needs of the brain. The part of the NVU known as a BBB controls selective access of endogenous and exogenous molecules to the brain tissue and efflux of metabolites to the blood, thereby providing maintenance of brain chemical homeostasis critical for efficient signal transduction and brain plasticity. In Alzheimer's disease, mitochondria are the target organelles for amyloid-induced neurodegeneration and alterations in NVU metabolic coupling or BBB breakdown. In this review we discuss understandings on mitochondria-driven NVU and BBB dysfunction, and how it might be studied in current and prospective NVU/BBB in vitro models for finding new approaches for the efficient pharmacotherapy of Alzheimer's disease.

Oxytocin and CD38 in the paraventricular nucleus play a critical role in paternal aggression in mice.

In mammals, the development of healthy offspring requires maternal care. Behavior by lactating mothers toward other individuals is an important component of maternal aggression. However, it is unclear whether fathers display aggression primed by pups (an external factor), and the protection mechanism is poorly understood. To address this question, we examined paternal aggression in the ICR mouse strain. We found that sires exposed to cues from pups and lactating dams showed stronger aggression toward intruders than did sires that were deprived of family cues or exposed to nonlactating mates. c-Fos immunohistochemistry showed that cells in both the paraventricular and supraoptic nuclei (PVN and SON, respectively) in the hypothalamus of sires exposed to any cues were highly activated. However, c-Fos activation in oxytocinergic neurons was increased only in sires exposed to pup cues and solely in the PVN. In Cd38-knockout sires, the presence of pups induced no or reduced parental aggression; however, this phenotype was recovered, that is, aggression increased to the wild-type level, after intraperitoneal administration of oxytocin (OT). Specific c-Fos activation patterns induced by pup cues were not found in the PVN of knockout sires. These results demonstrate that the PVN is one of the primary hypothalamic areas involved in paternal aggression and suggest that a CD38-dependent OT mechanism in oxytocinergic neurons is critical for part of the behavior associated with the protection of offspring by nurturing male mice.

Pericytes in Alzheimer's Disease: Novel Clues to Cerebral Amyloid Angiopathy Pathogenesis.

Pericytes in the central nervous system attract growing attention of neurobiologists because of obvious opportunities to use them as target cells in numerous brain diseases. Functional activity of pericytes includes control of integrity of the endothelial cell layer, regeneration of vascular cells, and regulation of microcirculation. Pericytes are well integrated in the so-called neurovascular unit (NVU) serving as a platform for effective communications of neurons, astrocytes, endothelial cells, and pericytes. Contribution of pericytes to the establishment and maintaining the structural and functional integrity of blood-brain barrier is confirmed in numerous experimental and clinical studies. The review covers current understandings on the role of pericytes in molecular pathogenesis of NVU/BBB dysfunction in Alzheimer's disease with the special focus on the development of cerebral amyloid angiopathy, deregulation of cerebral angiogenesis, and progression of BBB breakdown seen in Alzheimer's type neurodegeneration.

The inhibitory effect of LPS on the expression of GPR81 lactate receptor in blood-brain barrier model in vitro.

BACKGROUND: Lipopolysaccharide (LPS) is one of the main constituents of the cell wall of gram-negative bacteria. As an endotoxin, LPS induces neuroinflammation, which is associated with the blood-brain barrier impairment. Lactate is a metabolite with some significant physiological functions within the neurovascular unit/blood-brain barrier (BBB). Accumulation of extracellular and cerebrospinal fluid lactate is a specific feature of bacterial meningitis. However, the role of lactate production, transport, and sensing by lactate receptors GPR81 in the pathogenesis of bacterial neuroinflammation is still unknown. METHODS: In this study, we analyzed effects of LPS on the expression of GPR81 and MCT-1 and proliferation of cerebral endothelial cells in the BBB model in vitro. We used molecular profiling methods to measure the expression of GPR81, MCT-1, IL-1ß, and Ki67 in the cerebral endothelium after treatment with different concentrations of LPS followed by measuring the level of extracellular lactate, transendothelial electric resistance, and permeability of the endothelial cell layer. RESULTS: Our findings showed that exposure to LPS results in neuroinflammatory changes associated with decreased expression of GPR81 and MCT-1 in endothelial cells, as well as overproduction of IL-1ß and elevation of lactate concentrations in the extracellular space in a dose-dependent manner. LPS treatment reduced JAM tight junction protein expression in cerebral endothelial cells and altered BBB structural integrity in vitro. CONCLUSION: The impairment of lactate reception and transport might contribute to the alterations of BBB structural and functional integrity caused by LPS-mediated neuroinflammation.

Nutritional biomarkers: Current view and future perspectives.

There is a poor relationship between nutrient intake and existing nutritional biomarkers due to variety of factors affecting their sensitivity and specificity. To explore the impact of nutrients at molecular level and devising a sensitive biomarker, proteomics is a central technology with sirtuins as one of the most promising nutritional biomarker. Sirtuins (seven mammalian sirtuins reported so far) have been reported to perform protein deacetylases and ADP-ribosyltransferases activity. It is distributed in different cellular compartments thereby controlling several metabolic processes. Sirtuins are oxidized nicotinamide adenine dinucleotide dependent, which implicates a direct effect of the metabolic state of the cell on its activity. Calorie restriction upregulates the mammalian sirtuin protein levels in variety of tissues and organs where it acts upon both histone and nonhistone substrates. Sirtuin senses nutrient availability and impacts gluconeogenesis, glycolysis, and insulin sensitivity. It deacetylates and inhibits the nuclear receptor that activates fat synthesis and adipogenesis in the body, leading to fat loss and bringing favorable cellular and health changes. Sirtuins mediates intracellular response that promotes cell survival, DNA damage repair thereby increasing the cell longitivity. The activation of sirtuins brings a wide spectrum of other health benefits and its activity levels are indicative of nutritional status as well as disease progression in cancer, inflammation, obesity, cardiovascular diseases, and viral infections. There are several foods that activate sirtuin activity and offer significant health benefits by their consumption.

Molecular characterization of Streptococcus pneumoniae, particularly serotype19A/ST320, which emerged in Krasnoyarsk, Russia.

Streptococcus pneumoniae, a common human pathogen, colonizes the nasopharynx and causes diseases including acute otitis media (AOM). Herein, pneumococcal serotype distributions in children before and after PCV7 vaccination and in patients with pneumococcal disease in Siberian Russia (Krasnoyarsk) are reported. Analyses included antimicrobial susceptibility testing, sequence typing (ST), pulsed field gel electrophoresis, virulence-related surface protein gene (VSG) typing with novel primers and structural analysis by scanning electron microscopy. In healthy children (HC) prior to administration of PCV7, drug-susceptible serotype23F/ST1500 was a major pneumococcal genotype. In the PCV7 trial, multidrug-resistant serotype19A/ST320 emerged in vaccinees after PCV7, exhibiting a PCV7-induced serotype replacement. Multidrug-resistant serotype19A/ST320 was evident in patients with AOM. Community-acquired pneumonia (CAP) isolates showed genetic similarities to the AOM (ST320) genotype, constituting a common non-invasive AOM-CAP group. In contrast, meningitis isolates were more divergent. Overall, 25 ST types were identified; five (20%) of which were Krasnoyarsk-native. Regarding VSGs, PI-1 (rlrA/rrgB), PI-2 (pitA/B), psrP and cbpA were present at 54.3%, 38.6%, 48.6%, and 95.7%, respectively, with two major VSG content types, PI-1- /PI-2- /psrP+ /cbpA+ and PI-1+ /PI-2+ /psrP- /cbpA+ , being found for HC and non-invasive diseases, respectively. A major clone of serotype19A/ST320 (PI-1+ /PI-2+ ) produced the longest pneumococcal wire (pilus) structures in colonies. ST1016 (PI-1- /PI-2- ) in HC had HEp-2 cell-adherent pili. These results suggest that serotype19A/ST320 and related genotypes, with the VSG content type PI-1+ /PI-2+ /psrP- /cbpA+ , emerged in vaccinees after PCV7 in Siberia, accompanying diseases in non-vaccinated children, and that some genotypes (serotypes19A/ST320 and 18/ST1016) produced novel pneumococcal structures, predicting their roles in colony formation and adherence.

Establishment of neurogenic microenvironment in the neurovascular unit: the connexin 43 story.

Connexins (Cx) play an important role in the coordination of intercellular communication, and autocrine and paracrine regulation of cells within the neurovascular unit (NVU). Gap junctional mechanisms control proliferation and differentiation processes underlying neurogenesis and angiogenesis in the brain. Cx43 possesses some unique properties [the ability to form either intercellular channels permeable for regulatory molecules and ions or hemichannels open to the extracellular space to provide release of cell metabolites; functional coupling with nicotinamide adenine dinucleotide (NAD+)-consuming and NAD+-dependent enzymatic processes] which may be of great importance for the fate of the stem cells. Dynamic changes in Cx43 expression are associated with different stages of brain cells development either at embryonic or adult periods of ontogenesis. This review summarizes recent data on Cx43-controlled neurogenesis in the context of NVU development and functioning. Understanding the molecular mechanisms of gap junctional intercellular communication will support translational studies focused on the development of regeneration-based approaches for the therapy of central nervous system pathology.

Current progress and challenges in the development of brain tissue models: How to grow up the changeable brain in vitro?

In vitro modeling of brain tissue is a promising but not yet resolved problem in modern neurobiology and neuropharmacology. Complexity of the brain structure and diversity of cell-to-cell communication in (patho)physiological conditions make this task almost unachievable. However, establishment of novel in vitro brain models would ultimately lead to better understanding of development-associated or experience-driven brain plasticity, designing efficient approaches to restore aberrant brain functioning. The main goal of this review is to summarize the available data on methodological approaches that are currently in use, and to identify the most prospective trends in development of neurovascular unit, blood-brain barrier, blood-cerebrospinal fluid barrier, and neurogenic niche in vitro models. The manuscript focuses on the regulation of adult neurogenesis, cerebral microcirculation and fluids dynamics that should be reproduced in the in vitro 4D models to mimic brain development and its alterations in brain pathology. We discuss approaches that are critical for studying brain plasticity, deciphering the individual person-specific trajectory of brain development and aging, and testing new drug candidates in the in vitro models.

Machine learning approach for recognition and morphological analysis of isolated astrocytes in phase contrast microscopy.

Astrocytes are glycolytically active cells in the central nervous system playing a crucial role in various brain processes from homeostasis to neurotransmission. Astrocytes possess a complex branched morphology, frequently examined by fluorescent microscopy. However, staining and fixation may impact the properties of astrocytes, thereby affecting the accuracy of the experimental data of astrocytes dynamics and morphology. On the other hand, phase contrast microscopy can be used to study astrocytes morphology without affecting them, but the post-processing of the resulting low-contrast images is challenging. The main result of this work is a novel approach for recognition and morphological analysis of unstained astrocytes based on machine-learning recognition of microscopic images. We conducted a series of experiments involving the cultivation of isolated astrocytes from the rat brain cortex followed by microscopy. Using the proposed approach, we tracked the temporal evolution of the average total length of branches, branching, and area per astrocyte in our experiments. We believe that the proposed approach and the obtained experimental data will be of interest and benefit to the scientific communities in cell biology, biophysics, and machine learning.

Thermosensitive injectable fibrillar gels based on cellulose nanocrystals grafted with poly(N-isopropylacrylamide) as biocompatible brain implants.

Drug treatment of glioblastoma, the most aggressive and widespread form of brain cancer, is complicated due to the difficulty of penetration of chemotherapeutic drugs through the blood-brain barrier (BBB). Moreover, with surgical removal of tumors, in 90 % of cases they reappear near the original focus. To solve this problem, we propose to use hydrogel based on cellulose nanocrystals grafted with poly(N-isopropylacrylamide) (CNC-g-PNIPAM) as a promising material for filling postoperative cavities in the brain with the release of antitumor drugs. The CNC-g-PNIPAM is formed by "grafting to" method for precise control of molecular weight and grafting density. This colloidal system is liquid under injection conditions (at r. t.) and turns into a gel at human body temperature (when filling the postoperative area). It was shown for the first time that due to the rod-shaped of CNC, the gel has a fibrillar structure and, thus, mechanical properties similar to those of brain tissue, including nonlinear mechanics (strain-stiffening and compression softening). The biocompatibility of the hydrogel with primary brain cells is demonstrated. In addition, the release of the antitumor drug paclitaxel from the hydrogel and its antitumor activity is shown. The resulting nanocolloid system provides an innovative alternative approach to filling postoperative cavities and can be used for postoperative treatment due to the programmable release of drugs, as well as for in vitro modeling of tumor interaction with the BBB affecting drug transport in the brain.

Buckwheat-enriched diet alleviates bisphenol A mediated oxidative stress via modulation of sirtuin 1 and antioxidant status in experimental rats.

Present study investigated effect of dietary buckwheat in alleviating bisphenol A (BPA) mediated oxidative stress, concomitant sirtuin1 levels in serum, stomach, and liver of rats. Experimental group A and B ingested standard diet, C and D consumed buckwheat (30%); group A and C drank normal water, B and C had BPA contamination (10 mg L-1). Sirtuin1 mean B/A ratio nearing unity in all tissues reveals inertness of BPA towards sirtuin1. Dietary buckwheat improved sirtuin1 levels both in normal (mean C/A ratio of serum, 1.65; liver, 1.24; stomach, 1.78) and BPA fed state (mean D/B ratio of serum, 1.9; liver, 1.26; stomach, 1.75). Buckwheat augmented antioxidant status in BPA fed rats as seen in mean D/B ratio of serum (catalase, 2.4; glutathione reductase (GR), 1.33; Thiols, 1.2), liver (catalase, 2; GR, 2.5; Thiols, 1.36) and stomach (catalase, 1.31; GR, 1.5; Thiols, 1.33). Therefore, buckwheat counters BPA-led oxidative stress and modulates sirtuin1.