Origin, utilization, and recycling of nucleosides in the central nervous system

2011 ◽  
Vol 35 (4) ◽  
pp. 342-346 ◽  
Author(s):  
Piero Luigi Ipata
Keyword(s):  
Extracellular Space ◽  
Active Sites ◽  
Molecular Mechanisms ◽  
Brain Cell ◽  
Nucleoside Triphosphate ◽  
Pyrimidine Salvage ◽  
The Central Nervous System ◽  
Hydrolysis Of ◽  
The Brain ◽  
Brain Extracellular Space

The brain relies on the salvage of preformed purine and pyrimidine rings, mainly in the form of nucleosides, to maintain its nucleotide pool in the proper qualitative and quantitative balance. The transport of nucleosides from blood into neurons and glia is considered to be an essential prerequisite to enter their metabolic utilization in the brain. Recent lines of evidence have also suggested that local extracellular nucleoside triphosphate (NTP) degradation may contribute to brain nucleosides. Plasma membrane-located ectonucleotidases, with their active sites oriented toward the extracellular space, catalyze the successive hydrolysis of NTPs to their respective nucleosides. Apart from the well-established modulation of ATP, ADP, adenosine (the purinergic agonists), UTP, and UDP (the pyrimidinergic agonists) availability at their respective receptors, ectonucleotidases may also serve the local reutilization of nucleosides in the brain. After their production in the extracellular space by the ectonucleotidase system, nucleosides are transported into neurons and glia and converted back to NTPs via a set of purine and pyrimidine salvage enzymes. Finally, nucleotides are transported into brain cell vescicles or granules and released back into the extracellular space. The key teaching concepts to be included in a two-to three-lecture block on the molecular mechanisms of the local nucleoside recycling process, based on a cross talk between the brain extracellular space and cytosol, are discussed in this article.

scholarly journals Glymphatic System in the Central Nervous System, a Novel Therapeutic Direction Against Brain Edema After Stroke

2021 ◽  
Vol 13 ◽  
Author(s):  
Xiangyue Zhou ◽  
Youwei Li ◽  
Cameron Lenahan ◽  
Yibo Ou ◽  
Minghuan Wang ◽  
...  
Keyword(s):  
Brain Edema ◽  
Brain Tissue ◽  
Molecular Mechanisms ◽  
Glymphatic System ◽  
System A ◽  
Function Recovery ◽  
The Central Nervous System ◽  
The Stability ◽  
The Brain

Stroke is the destruction of brain function and structure, and is caused by either cerebrovascular obstruction or rupture. It is a disease associated with high mortality and disability worldwide. Brain edema after stroke is an important factor affecting neurologic function recovery. The glymphatic system is a recently discovered cerebrospinal fluid (CSF) transport system. Through the perivascular space and aquaporin 4 (AQP4) on astrocytes, it promotes the exchange of CSF and interstitial fluid (ISF), clears brain metabolic waste, and maintains the stability of the internal environment within the brain. Excessive accumulation of fluid in the brain tissue causes cerebral edema, but the glymphatic system plays an important role in the process of both intake and removal of fluid within the brain. The changes in the glymphatic system after stroke may be an important contributor to brain edema. Understanding and targeting the molecular mechanisms and the role of the glymphatic system in the formation and regression of brain edema after stroke could promote the exclusion of fluids in the brain tissue and promote the recovery of neurological function in stroke patients. In this review, we will discuss the physiology of the glymphatic system, as well as the related mechanisms and therapeutic targets involved in the formation of brain edema after stroke, which could provide a new direction for research against brain edema after stroke.

Сellular and Molecular Mechanisms of Proinflammatory Monocytes Participation in the Pathogenesis of Mental Disorders. Part 3

Psychiatry ◽  
2021 ◽  
Vol 19 (4) ◽  
pp. 125-134
Author(s):  
E. F. Vasilyeva ◽  
O. S. Brusov
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Mental Disorders ◽  
Molecular Mechanisms ◽  
Microglial Cells ◽  
Inflammatory Reactions ◽  
Mental Diseases ◽  
The Central Nervous System ◽  
The Brain

Background: at present, the important role of the monocyte-macrophage link of immunity in the pathogenesis of mental diseases has been determined. In the first and second parts of our review, the cellular and molecular mechanisms of activation of monocytes/macrophages, which secreting proinflammatory CD16 receptors, cytokines, chemokines and receptors to them, in the development of systemic immune inflammation in the pathogenesis of somatic diseases and mental disorders, including schizophrenia, bipolar affective disorder (BAD) and depression were analyzed. The association of high levels of proinflammatory activity of monocytes/macrophages in patients with mental disorders with somatic comorbidity, including immune system diseases, is shown. It is known that proinflammatory monocytes of peripheral blood, as a result of violation of the integrity of the hematoencephalic barrier can migrate to the central nervous system and activate the resident brain cells — microglia, causing its activation. Activation of microglia can lead to the development of neuroinammation and neurodegenerative processes in the brain and, as a result, to cognitive disorders. The aim of review: to analyze the results of the main scientific studies concerning the role of cellular and molecular mechanisms of peripheral blood monocytes interaction with microglial cells and platelets in the development of neuroinflammation in the pathogenesis of mental disorders, including Alzheimer’s disease (AD). Material and methods: keywords “mental disorders, AD, proinflammatory monocytes, microglia, neuroinflammation, cytokines, chemokines, cell adhesion molecules, platelets, microvesicles” were used to search for articles of domestic and foreign authors published over the past 30 years in the databases PubMed, eLibrary, Science Direct and EMBASE. Conclusion: this review analyzes the results of studies which show that monocytes/macrophages and microglia have similar gene expression profiles in schizophrenia, BAD, depression, and AD and also perform similar functions: phagocytosis and inflammatory responses. Monocytes recruited to the central nervous system stimulate the increased production of proinflammatory cytokines IL-1, IL-6, tumor necrosis factor alpha (TNF-α), chemokines, for example, MCP-1 (Monocyte chemotactic protein-1) by microglial cells. This promotes the recruitment of microglial cells to the sites of neuronal damage, and also enhances the formation of the brain protein beta-amyloid (Aβ). The results of modern studies are presented, indicating that platelets are involved in systemic inflammatory reactions, where they interact with monocytes to form monocyte-platelet aggregates (MTA), which induce the activation of monocytes with a pro inflammatory phenotype. In the last decade, it has been established that activated platelets and other cells of the immune system, including monocytes, detached microvesicles (MV) from the membrane. It has been shown that MV are involved as messengers in the transport of biologically active lipids, cytokines, complement, and other molecules that can cause exacerbation of systemic inflammatory reactions. The presented review allows us to expand our knowledge about the cellular and molecular aspects of the interaction of monocytes/macrophages with microglial cells and platelets in the development of neuroinflammation and cognitive decline in the pathogenesis of mental diseases and in AD, and also helps in the search for specific biomarkers of the clinical severity of mental disorder in patients and the prospects for their response to treatment.

scholarly journals Altered central TRPV4 expression and lipid raft association related to inappropriate vasopressin secretion in cirrhotic rats

2009 ◽  
Vol 296 (2) ◽  
pp. R454-R466 ◽  
Author(s):  
Flávia Regina Carreño ◽  
Lisa L. Ji ◽  
J. Thomas Cunningham
Keyword(s):  
Lipid Raft ◽  
Supraoptic Nucleus ◽  
Molecular Mechanisms ◽  
Bile Duct Ligation ◽  
Plasma Osmolality ◽  
Plasma Renin ◽  
Duct Ligation ◽  
The Central Nervous System ◽  
Vasopressin Secretion ◽  
The Brain

Inappropriate vasopressin (AVP) release causes dilutional hyponatremia in many pathophysiological states such as cirrhosis. The central molecular mechanisms that mediate inappropriate AVP release are unknown. We tested the hypothesis that changes in the expression or trafficking of TRPV4 in the central nervous system may contribute to inappropriate AVP release in the bile duct ligation (BDL) model of cirrhosis in the rat. Four weeks after surgery, BDL rats demonstrated significantly increased plasma vasopressin and plasma renin activity (PRA), hypervolemia, and decreased plasma osmolality. These effects were blocked by providing BDL rats with 2% saline to drink for 15 days. TRPV4 protein expression was significantly increased in brain punches from BDL rats containing the supraoptic nucleus (SON) of the hypothalamus (100% ± 11 to 157% ± 4.8), and this effect was blocked in BDL rats given saline. Immunohistochemistry demonstrated a significant increase in TRPV4-positive cells and the percentage of AVP neurons that also were TRPV4-positive in the SON of BDL rats. In the hypothalamus of BDL rats, TRPV4 lipid raft association increased compared with sham (from 100% ± 2.1 to 326.1% ± 16). This effect was significantly attenuated in BDL rats given 2% saline to drink (174% ± 11). In the brain stem, TRPV4 lipid raft association was reduced by BDL and inversely related to plasma AVP and PRA. We speculate that changes in TRPV4 expression and compartmentalization within lipid rafts could contribute to a feed-forward mechanism related to AVP release in cirrhosis.

scholarly journals Preproglucagon neurons in the hindbrain have IL-6 receptor-α and show Ca2+ influx in response to IL-6

2016 ◽  
Vol 311 (1) ◽  
pp. R115-R123 ◽  
Author(s):  
Fredrik Anesten ◽  
Marie K. Holt ◽  
Erik Schéle ◽  
Vilborg Pálsdóttir ◽  
Frank Reimann ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Food Intake ◽  
Extracellular Space ◽  
Solitary Tract ◽  
Neuronal Marker ◽  
Reporter Mice ◽  
The Central Nervous System ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
The Brain

Neuronal circuits in the hypothalamus and hindbrain are of importance for control of food intake, energy expenditure, and fat mass. We have recently shown that treatment with exendin-4 (Ex-4), an analog of the proglucagon-derived molecule glucagon-like peptide 1 (GLP-1), markedly increases mRNA expression of the cytokine interleukin-6 (IL-6) in the hypothalamus and hindbrain and that this increase partly mediates the suppression of food intake and body weight by Ex-4. Endogenous GLP-1 in the central nervous system (CNS) is produced by preproglucagon (PPG) neurons of the nucleus of the solitary tract (NTS) in the hindbrain. These neurons project to various parts of the brain, including the hypothalamus. Outside the brain, IL-6 stimulates GLP-1 secretion from the gut and pancreas. In this study, we aim to investigate whether IL-6 can affect GLP-1-producing PPG neurons in the nucleus of the solitary tract (NTS) in mouse hindbrain via the ligand binding part of the IL-6 receptor, IL-6 receptor-α (IL-6Rα). Using immunohistochemistry, we found that IL-6Rα was localized on PPG neurons of the NTS. Recordings of these neurons in GCaMP3/GLP-1 reporter mice showed that IL-6 enhances cytosolic Ca2+ concentration in neurons capable of expressing PPG. We also show that the Ca2+ increase originates from the extracellular space. Furthermore, we found that IL-6Rα was localized on cells in the caudal hindbrain expressing immunoreactive NeuN (a neuronal marker) or CNP:ase (an oligodendrocyte marker). In summary, IL-6Rα is present on PPG neurons in the NTS, and IL-6 can stimulate these cells by increasing influx of Ca2+ to the cytosol from the extracellular space.

scholarly journals Methamphetamine-Triggered Neurotoxicity in Human Dorsolateral Prefrontal Cortex

2021 ◽  
Vol 10 ◽  
pp. 2016
Author(s):  
Ali Zare ◽  
Alireza Ghanbari ◽  
Mohammad Javad Hoseinpour ◽  
Mahdi Eskandarian Boroujeni ◽  
Alimohammad Alimohammadi ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Prefrontal Cortex ◽  
Dorsolateral Prefrontal Cortex ◽  
Animal Studies ◽  
Molecular Mechanisms ◽  
Metabolic Activation ◽  
Neural Cells ◽  
Dorsolateral Prefrontal ◽  
The Central Nervous System ◽  
The Brain

Background: Methamphetamine (MA), is an extremely addictive stimulant that adversely affects the central nervous system. Accumulating evidence indicates that molecular mechanisms such as oxidative stress, apoptosis, and autophagy are involved in the toxicity of MA. Considering experimental animal studies exhibiting MA-induced neurotoxicity, the relevance of these findings needs to be evidently elucidated in human MA users. It is generally assumed that multiple chemical substances released in the brain following MA-induced metabolic activation are primary factors underlying damage of neural cells. Hence, this study aimed to investigate the role of autophagy and apoptosis as well as oxidative stress in the brain of postmortem MA-induced toxicity. Materials and Methods: In this study, we determine the gene expression of autophagy and apoptosis, including BECN1, MAP1ALC3, CASP8, TP53, and BAX genes in ten healthy controls and ten chronic users of MA postmortem dorsolateral prefrontal cortex (DLPFC) by real-time polymerase chain reaction. Also, we applied immunohistochemistry in formalin-fixed and paraffin-embedded human brain samples to analyze brain-derived neurotrophic factor (BDNF). Also, spectrophotometry was performed to measure glutathione (GSH) content. Results: The expression level of apoptotic and autophagic genes (BECN1, MAP1ALC3, CASP8, TP53, and BAX) were significantly elevated, while GSH content and BDNF showed substantial reductions in DLPFC of chronic MA users. Discussion: Our data showed that MA addiction provokes transduction pathways, namely apoptosis and autophagy, along with oxidative mechanisms in DLPFC. Also, MA induces multiple functional and structural perturbations in the brain, determining its toxicity and possibly contributing to neurotoxicity. [GMJ.2021;10:e2016]

scholarly journals Primary Amoebic Meningoencephalitis by Naegleria fowleri: Pathogenesis and Treatments

Biomolecules ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1320 ◽  
Author(s):  
Andrea Güémez ◽  
Elisa García
Keyword(s):  
Molecular Mechanisms ◽  
Case Reports ◽  
Naegleria Fowleri ◽  
Initial Exposure ◽  
Immunomodulatory Agents ◽  
Primary Amoebic Meningoencephalitis ◽  
The Central Nervous System ◽  
Nægleria Fowleri ◽  
Amoebic Meningoencephalitis ◽  
The Brain

Naegleria fowleri is a free-living amoeba (FLA) that is commonly known as the “brain-eating amoeba.” This parasite can invade the central nervous system (CNS), causing an acute and fulminating infection known as primary amoebic meningoencephalitis (PAM). Even though PAM is characterized by low morbidity, it has shown a mortality rate of 98%, usually causing death in less than two weeks after the initial exposure. This review summarizes the most recent information about N. fowleri, its pathogenic molecular mechanisms, and the neuropathological processes implicated. Additionally, this review includes the main therapeutic strategies described in case reports and preclinical studies, including the possible use of immunomodulatory agents to decrease neurological damage.

Alcohol Dementia, Wernicke’s Encephalopathy, and Korsakoff’s Syndrome

2019 ◽  
pp. 742-758
Author(s):  
Marlene Oscar-Berman, ◽  
Nasim Maleki
Keyword(s):  
Molecular Mechanisms ◽  
Neurological Complications ◽  
Wernicke’S Encephalopathy ◽  
Wernicke's Encephalopathy ◽  
Korsakoff’S Syndrome ◽  
Emotional Processes ◽  
Korsakoff's Syndrome ◽  
Neuropsychological Characteristics ◽  
The Central Nervous System ◽  
The Brain

Chronic alcohol consumption has direct effects on the central nervous system and is among the leading causes of cognitive impairment and dementia. Alcohol-related dementia, Wernicke’s encephalopathy, and Korsakoff’s syndrome are among the most common forms of severe alcoholism-related neurological complications that are associated with widespread abnormalities in the brain, as well as impairments of multiple mental and emotional processes. Abnormalities have been consistently reported in association with Wernicke’s encephalopathy and Korsakoff’s syndrome, but alcohol-related dementia remains less well characterized. This chapter reviews the neurological and neuropsychological characteristics of these conditions, associated changes in the brain, potential molecular mechanisms involved, and some of the treatment or rehabilitation options. Future use of evidence-based diagnostic test-selection is advised to assist in refining differential diagnoses.

scholarly journals Synucleinopathy alters nanoscale organization and diffusion in the brain extracellular space through hyaluronan remodeling

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Federico N. Soria ◽  
Chiara Paviolo ◽  
Evelyne Doudnikoff ◽  
Marie-Laure Arotcarena ◽  
Antony Lee ◽  
...  
Keyword(s):  
Extracellular Space ◽  
The Brain ◽  
And Diffusion ◽  
Brain Extracellular Space

How Stress Physically Re-shapes the Brain: Impact on Brain Cell Shapes, Numbers and Connections in Psychiatric Disorders

2019 ◽  
Author(s):  
Dominic Kaul ◽  
Sibylle Schwab ◽  
Naguib Mechawar ◽  
Natalie Matosin
Keyword(s):  
Psychiatric Disorders ◽  
Molecular Mechanisms ◽  
Brain Regions ◽  
Brain Cell ◽  
Intervention Strategies ◽  
Traumatic Experiences ◽  
Brain Pathology ◽  
Cell Shapes ◽  
Brain Circuitry ◽  
The Brain

Exposure to stressful or traumatic experiences is one of the most robust risk factors for severe psychiatric disorders and has been shown to reshape entire brain regions, especially those involved in processing the stress response. This is likely underpinned by alterations to brain cell shapes, numbers and their connections, thus changing brain circuitry to enable coping with the current and future stress. In this review, we present a model for how stress re-shapes the brain, consolidating evidence of morphometric changes and the cellular and molecular mechanisms that underlie them. We illustrate how the temporal effects of stress can cause persistent remodelling of brain cells, highlighting that an individual's stress history is important for understanding psychiatric disorder risk and development. Understanding how stress re-shapes the brain is a critical step for understanding stress as a risk factor for brain pathology, and to develop appropriate biomarkers, treatments and intervention strategies.

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