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Tasca CI, Zuccarini M, Di Iorio P, Ciruela F. Lessons from the physiological role of guanosine in neurodegeneration and cancer: Toward a multimodal mechanism of action? Purinergic Signal 2024:10.1007/s11302-024-10033-y. [PMID: 39004650 DOI: 10.1007/s11302-024-10033-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 06/18/2024] [Indexed: 07/16/2024] Open
Abstract
Neurodegenerative diseases and brain tumours represent important health challenges due to their severe nature and debilitating consequences that require substantial medical care. Interestingly, these conditions share common physiological characteristics, namely increased glutamate, and adenosine transmission, which are often associated with cellular dysregulation and damage. Guanosine, an endogenous nucleoside, is safe and exerts neuroprotective effects in preclinical models of excitotoxicity, along with cytotoxic effects on tumour cells. However, the lack of well-defined mechanisms of action for guanosine hinders a comprehensive understanding of its physiological effects. In fact, the absence of specific receptors for guanosine impedes the development of structure-activity research programs to develop guanosine derivatives for therapeutic purposes. Alternatively, given its apparent interaction with the adenosinergic system, it is plausible that guanosine exerts its neuroprotective and anti-tumorigenic effects by modulating adenosine transmission through undisclosed mechanisms involving adenosine receptors, transporters, and purinergic metabolism. Here, several potential molecular mechanisms behind the protective actions of guanosine will be discussed. First, we explore its potential interaction with adenosine receptors (A1R and A2AR), including the A1R-A2AR heteromer. In addition, we consider the impact of guanosine on extracellular adenosine levels and the role of guanine-based purine-converting enzymes. Collectively, the diverse cellular functions of guanosine as neuroprotective and antiproliferative agent suggest a multimodal and complementary mechanism of action.
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Affiliation(s)
- Carla Inês Tasca
- Department of Biochemistry, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
- Laboratory of Neurochemistry-4, Neuroscience Program/Biochemistry Program, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
| | - Mariachiara Zuccarini
- Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, 66100, Chieti, Italy
- Center for Advanced Studies and Technologies (CAST), University of Chieti-Pescara, 66100, Chieti, Italy
| | - Patrizia Di Iorio
- Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, 66100, Chieti, Italy
- Center for Advanced Studies and Technologies (CAST), University of Chieti-Pescara, 66100, Chieti, Italy
| | - Francisco Ciruela
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L'Hospitalet de Llobregat, Barcelona, Spain
- Neuropharmacology & Pain Group, Neuroscience Program, Bellvitge Institute for Biomedical Research, 08907L'Hospitalet de Llobregat, Bellvitge, Spain
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2
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Parmeggiani B, Signori MF, Cecatto C, Frusciante MR, Marcuzzo MB, Souza DG, Ribeiro RT, Seminotti B, Gomes de Souza DO, Ribeiro CAJ, Wajner M, Leipnitz G. Glycine disrupts myelin, glutamatergic neurotransmission, and redox homeostasis in a neonatal model for non ketotic hyperglycinemia. Biochimie 2024; 219:21-32. [PMID: 37541567 DOI: 10.1016/j.biochi.2023.07.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/26/2023] [Accepted: 07/30/2023] [Indexed: 08/06/2023]
Abstract
Non ketotic hyperglycinemia (NKH) is an inborn error of glycine metabolism caused by mutations in the genes encoding glycine cleavage system proteins. Classic NKH has a neonatal onset, and patients present with severe neurodegeneration. Although glycine accumulation has been implicated in NKH pathophysiology, the exact mechanisms underlying the neurological damage and white matter alterations remain unclear. We investigated the effects of glycine in the brain of neonatal rats and MO3.13 oligodendroglial cells. Glycine decreased myelin basic protein (MBP) and myelin-associated glycoprotein (MAG) in the corpus callosum and striatum of rats on post-natal day (PND) 15. Glycine also reduced neuroglycan 2 (NG2) and N-methyl-d-aspartate receptor subunit 1 (NR1) in the cerebral cortex and striatum on PND15. Moreover, glycine reduced striatal glutamate aspartate transporter 1 (GLAST) content and neuronal nucleus (NeuN), and increased glial fibrillary acidic protein (GFAP) on PND15. Glycine also increased DCFH oxidation and malondialdehyde levels and decreased GSH concentrations in the cerebral cortex and striatum on PND6, but not on PND15. Glycine further reduced viability but did not alter DCFH oxidation and GSH levels in MO3.13 cells after 48- and 72-h incubation. These data indicate that impairment of myelin structure and glutamatergic system and induction of oxidative stress are involved in the neuropathophysiology of NKH.
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Affiliation(s)
- Belisa Parmeggiani
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
| | - Marian Flores Signori
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Cristiane Cecatto
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Marina Rocha Frusciante
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Manuela Bianchin Marcuzzo
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Débora Guerini Souza
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Rafael Teixeira Ribeiro
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Bianca Seminotti
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Diogo Onofre Gomes de Souza
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - César Augusto João Ribeiro
- Natural and Humanities Sciences Center, Universidade Federal do ABC, São Bernardo do Campo, SP, 09606-070, Brazil
| | - Moacir Wajner
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Serviço de Genética Médica do Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - Guilhian Leipnitz
- Programa de Pós-Graduação em Ciências Biológicas - Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
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3
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Weese-Myers ME, Cryan MT, Witt CE, Caldwell KCN, Modi B, Ross AE. Dynamic and Rapid Detection of Guanosine during Ischemia. ACS Chem Neurosci 2023; 14:1646-1658. [PMID: 37040534 PMCID: PMC10265669 DOI: 10.1021/acschemneuro.3c00048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023] Open
Abstract
Guanosine acts in both neuroprotective and neurosignaling pathways in the central nervous system; in this paper, we present the first fast voltammetric measurements of endogenous guanosine release during pre- and post-ischemic conditions. We discuss the metric of our measurements via analysis of event concentration, duration, and interevent time of rapid guanosine release. We observe changes across all three metrics from our normoxic to ischemic conditions. Pharmacological studies were performed to confirm that guanosine release is a calcium-dependent process and that the signaling observed is purinergic. Finally, we show the validity of our ischemic model via staining and fluorescent imaging. Overall, this paper sets the tone for rapid monitoring of guanosine and provides a platform to investigate the extent to which guanosine accumulates at the site of brain injury, i.e., ischemia.
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Affiliation(s)
- Moriah E. Weese-Myers
- University of Cincinnati, Department of Chemistry, 312 College Dr., 404 Crosley Tower, Cincinnati, OH 45221-0172
- Co-first author
| | - Michael T. Cryan
- University of Cincinnati, Department of Chemistry, 312 College Dr., 404 Crosley Tower, Cincinnati, OH 45221-0172
- Co-first author
| | - Colby E. Witt
- University of Cincinnati, Department of Chemistry, 312 College Dr., 404 Crosley Tower, Cincinnati, OH 45221-0172
| | - Kaejaren C. N. Caldwell
- University of Cincinnati, Department of Chemistry, 312 College Dr., 404 Crosley Tower, Cincinnati, OH 45221-0172
| | - Bindu Modi
- University of Cincinnati, Department of Chemistry, 312 College Dr., 404 Crosley Tower, Cincinnati, OH 45221-0172
| | - Ashley E. Ross
- University of Cincinnati, Department of Chemistry, 312 College Dr., 404 Crosley Tower, Cincinnati, OH 45221-0172
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Camargo A, Dalmagro AP, Altê GA, Zeni ALB, Tasca CI, Rodrigues ALS. NMDA receptor-mediated modulation on glutamine synthetase and glial glutamate transporter GLT-1 is involved in the antidepressant-like and neuroprotective effects of guanosine. Chem Biol Interact 2023; 375:110440. [PMID: 36878458 DOI: 10.1016/j.cbi.2023.110440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 02/14/2023] [Accepted: 03/03/2023] [Indexed: 03/07/2023]
Abstract
Guanosine has been reported to elicit antidepressant-like responses in rodents, but if these actions are associated with its ability to afford neuroprotection against glutamate-induced toxicity still needs to be fully understood. Therefore, this study investigated the antidepressant-like and neuroprotective effects elicited by guanosine in mice and evaluated the possible involvement of NMDA receptors, glutamine synthetase, and GLT-1 in these responses. We found that guanosine (0.05 mg/kg, but not 0.01 mg/kg, p. o.) was effective in producing an antidepressant-like effect and protecting hippocampal and prefrontocortical slices against glutamate-induced damage. Our results also unveiled that ketamine (1 mg/kg, but not 0.1 mg/kg, i. p, an NMDA receptor antagonist) effectively elicited antidepressant-like actions and protected hippocampal and prefrontocortical slices against glutamatergic toxicity. Furthermore, the combined administration of sub-effective doses of guanosine (0.01 mg/kg, p. o.) with ketamine (0.1 mg/kg, i. p.) promoted an antidepressant-like effect and augmented glutamine synthetase activity and GLT-1 immunocontent in the hippocampus, but not in the prefrontal cortex. Our results also showed that the combination of sub-effective doses of ketamine and guanosine, at the same protocol schedule that exhibited an antidepressant-like effect, effectively abolished glutamate-induced damage in hippocampal and prefrontocortical slices. Our in vitro results reinforce that guanosine, ketamine, or sub-effective concentrations of guanosine plus ketamine protect against glutamate exposure by modulating glutamine synthetase activity and GLT-1 levels. Finally, molecular docking analysis suggests that guanosine might interact with NMDA receptors at the ketamine or glycine/d-serine co-agonist binding sites. These findings provide support for the premise that guanosine has antidepressant-like effects and should be further investigated for depression management.
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Affiliation(s)
- Anderson Camargo
- Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, Florianópolis, 88040-900, Santa Catarina, Brazil
| | - Ana P Dalmagro
- Department of Natural Sciences, Center of Natural and Exact Sciences, Universidade Regional de Blumenau, Blumenau CEP, 89030-903, Santa Catarina, Brazil
| | - Glorister A Altê
- Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, Florianópolis, 88040-900, Santa Catarina, Brazil
| | - Ana Lúcia B Zeni
- Department of Natural Sciences, Center of Natural and Exact Sciences, Universidade Regional de Blumenau, Blumenau CEP, 89030-903, Santa Catarina, Brazil
| | - Carla I Tasca
- Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, Florianópolis, 88040-900, Santa Catarina, Brazil
| | - Ana Lúcia S Rodrigues
- Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, Florianópolis, 88040-900, Santa Catarina, Brazil.
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Chojnowski K, Opielka M, Nazar W, Kowianski P, Smolenski RT. Neuroprotective Effects of Guanosine in Ischemic Stroke-Small Steps towards Effective Therapy. Int J Mol Sci 2021; 22:6898. [PMID: 34199004 PMCID: PMC8268871 DOI: 10.3390/ijms22136898] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/22/2021] [Accepted: 06/23/2021] [Indexed: 12/12/2022] Open
Abstract
Guanosine (Guo) is a nucleotide metabolite that acts as a potent neuromodulator with neurotrophic and regenerative properties in neurological disorders. Under brain ischemia or trauma, Guo is released to the extracellular milieu and its concentration substantially raises. In vitro studies on brain tissue slices or cell lines subjected to ischemic conditions demonstrated that Guo counteracts destructive events that occur during ischemic conditions, e.g., glutaminergic excitotoxicity, reactive oxygen and nitrogen species production. Moreover, Guo mitigates neuroinflammation and regulates post-translational processing. Guo asserts its neuroprotective effects via interplay with adenosine receptors, potassium channels, and excitatory amino acid transporters. Subsequently, guanosine activates several prosurvival molecular pathways including PI3K/Akt (PI3K) and MEK/ERK. Due to systemic degradation, the half-life of exogenous Guo is relatively low, thus creating difficulty regarding adequate exogenous Guo distribution. Nevertheless, in vivo studies performed on ischemic stroke rodent models provide promising results presenting a sustained decrease in infarct volume, improved neurological outcome, decrease in proinflammatory events, and stimulation of neuroregeneration through the release of neurotrophic factors. In this comprehensive review, we discuss molecular signaling related to Guo protection against brain ischemia. We present recent advances, limitations, and prospects in exogenous guanosine therapy in the context of ischemic stroke.
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Affiliation(s)
- Karol Chojnowski
- Faculty of Medicine, Medical University of Gdańsk, Marii Skłodowskiej-Curie 3a, 80-210 Gdańsk, Poland; (K.C.); (W.N.)
| | - Mikolaj Opielka
- Department of Biochemistry, Medical University of Gdansk, 1 Debinki St., 80-211 Gdansk, Poland
- International Research Agenda 3P—Medicine Laboratory, Medical University of Gdańsk, 3A Sklodowskiej-Curie Street, 80-210 Gdansk, Poland
| | - Wojciech Nazar
- Faculty of Medicine, Medical University of Gdańsk, Marii Skłodowskiej-Curie 3a, 80-210 Gdańsk, Poland; (K.C.); (W.N.)
| | - Przemyslaw Kowianski
- Department of Anatomy and Neurobiology, Medical University of Gdansk, 1 Debinki Street, 80-211 Gdańsk, Poland;
- Institute of Health Sciences, Pomeranian University of Słupsk, Bohaterów Westerplatte 64, 76-200 Słupsk, Poland
| | - Ryszard T. Smolenski
- Department of Biochemistry, Medical University of Gdansk, 1 Debinki St., 80-211 Gdansk, Poland
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Zhu D, Zhen Q, Xin J, Ma H, Pang H, Tan L, Wang X. In situ hierarchical encapsulation of bimetallic selenides into honeycomb-like nitrogen doped porous carbon nanosheets for highly sensitive and selective guanosine detection. J Colloid Interface Sci 2021; 598:181-192. [PMID: 33901845 DOI: 10.1016/j.jcis.2021.04.048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/30/2021] [Accepted: 04/11/2021] [Indexed: 02/07/2023]
Abstract
An innovative electrochemical nanocomposite for the detection of guanosine (Gua) was proposed by in situ encapsulation of nickel-iron bimetallic selenides confined into honeycomb-like nitrogen doped porous carbon nanosheets, denoted as (Ni,Fe)Se2/N-PCNs. The porous carbon nanosheets were prepared by utilizing nickel-iron layered double hydroxide (Ni-Fe LDH) as the substrate and zeolitic imidazolate frameworks (ZIF-67) nanocrystals as the sacrificial templates via hydrothermal synthesis, followed by a process of acid etching and pyrolysis selenylation. Interestingly, the nickel-ferric bimetallic selenides material (Ni,Fe)Se2, is rarely fabricated successfully using selenylation treatment, which is a highly conductive and robust support to promote the electron transport. Meanwhile, the obtained (Ni,Fe)Se2/N-PCNs have the favorable architectural features of both unique three-dimensional (3D) porous structural and hierarchical connectivity, which are expected to provide more active sites for electrochemical reactions and ease of electron, ion, and biomolecule penetration. Benefiting from the inherent virtues of its composition, together with unique structural advantages, the (Ni,Fe)Se2/N-PCNs possess ideal sensing properties for guanosine detection with a low detection limit of 1.20 × 10-8 M, a wide linear range of 5.30 × 10-8 ~ 2.27 × 10-4 M and a good stability. Superb selectivity for potential interfering species and superb recoveries in serum suggests its feasibility for practical applications.
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Affiliation(s)
- Di Zhu
- School of Materials Science and Engineering, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin, 150040, PR China; College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar, 161006, PR China
| | - Qingfang Zhen
- School of Pharmacy, Heilongjiang University of Chinese Medicine, Harbin, 150040, PR China
| | - Jianjiao Xin
- College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar, 161006, PR China
| | - Huiyuan Ma
- School of Materials Science and Engineering, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin, 150040, PR China.
| | - Haijun Pang
- School of Materials Science and Engineering, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin, 150040, PR China
| | - Lichao Tan
- School of Materials Science and Engineering, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin, 150040, PR China
| | - Xinming Wang
- School of Materials Science and Engineering, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin, 150040, PR China
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Neurobiology, Functions, and Relevance of Excitatory Amino Acid Transporters (EAATs) to Treatment of Refractory Epilepsy. CNS Drugs 2020; 34:1089-1103. [PMID: 32926322 DOI: 10.1007/s40263-020-00764-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Epilepsy is one of the most prevalent and devastating neurological disorders characterized by episodes of unusual sensations, loss of awareness, and reoccurring seizures. The frequency and intensity of epileptic fits can vary to a great degree, with almost a third of all cases resistant to available therapies. At present, there is a major unmet need for effective and specific therapeutic intervention. Impairments of the exquisite balance between excitatory and inhibitory synaptic processes in the brain are considered key in the onset and pathophysiology of the disease. As the primary excitatory neurotransmitter in the central nervous system, glutamate has been implicated in the process, with the glutamatergic system holding center stage in the pathobiology as well as in developing disease-modifying therapies. Emerging data pinpoint impairments of glutamate clearance as one of the key causative factors in drug-resistant disease forms. Reinstatement of glutamate homeostasis using pharmacological and genetic modulation of glutamate clearance is therefore considered to be of major translational relevance. In this article, we review the neurobiological and clinical evidence suggesting complex aberrations in the activity and functions of excitatory amino acid transporters (EAATs) in epilepsy, with knock-on effects on glutamate homeostasis as a leading cause for the development of refractory forms. We consider the emerging data on pharmacological and genetic manipulations of EAATs, with reference to seizures and glutamate dyshomeostasis, and review their fundamental and translational relevance. We discuss the most recent advances in the EAATs research in human and animal models, along with numerous questions that remain open for debate and critical appraisal. Contrary to the widely held view on EAATs as a promising therapeutic target for management of refractory epilepsy as well as other neurological and psychiatric conditions related to glutamatergic hyperactivity and glutamate-induced cytotoxicity, we stress that the true relevance of EAAT2 as a target for medical intervention remains to be fully appreciated and verified. Despite decades of research, the emerging properties and functional characteristics of glutamate transporters and their relationship with neurophysiological and behavioral correlates of epilepsy challenge the current perception of this disease and fit unambiguously in neither EAATs functional deficit nor in reversal models. We stress the pressing need for new approaches and models for research and restoration of the physiological activity of glutamate transporters and synaptic transmission to achieve much needed therapeutic effects. The complex mechanism of EAATs regulation by multiple factors, including changes in the electrochemical environment and ionic gradients related to epileptic hyperactivity, impose major therapeutic challenges. As a final note, we consider the evolving views and present a cautious perspective on the key areas of future progress in the field towards better management and treatment of refractory disease forms.
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Li Y, Liu J. Highly Specific Recognition of Guanosine Using Engineered Base-Excised Aptamers. Chemistry 2020; 26:13644-13651. [PMID: 32700427 DOI: 10.1002/chem.202001835] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/20/2020] [Indexed: 12/18/2022]
Abstract
Purines and their derivatives are highly important molecules in biology for nucleic acid synthesis, energy storage, and signaling. Although many DNA aptamers have been obtained for binding adenine derivatives such as adenosine, adenosine monophosphate, and adenosine triphosphate, success for the specific binding of guanosine has been limited. Instead of performing new aptamer selections, we report herein a base-excision strategy to engineer existing aptamers to bind guanosine. Both a Na+ -binding aptamer and the classical adenosine aptamer have been manipulated as base-excising scaffolds. A total of seven guanosine aptamers were designed, of which the G16-deleted Na+ aptamer showed the highest bindng specificity and affinity for guanosine with an apparent dissociation constant of 0.78 mm. Single monophosphate difference in the target molecule was also recognizable. The generality of both the aptamer scaffold and excised site were systematically studied. Overall, this work provides a few guanosine binding aptamers by using a non-SELEX method. It also provides deeper insights into the engineering of aptamers for molecular recognition.
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Affiliation(s)
- Yuqing Li
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
| | - Juewen Liu
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
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9
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Nonose Y, Pieper LZ, da Silva JS, Longoni A, Apel RV, Meira-Martins LA, Grings M, Leipnitz G, Souza DO, de Assis AM. Guanosine enhances glutamate uptake and oxidation, preventing oxidative stress in mouse hippocampal slices submitted to high glutamate levels. Brain Res 2020; 1748:147080. [PMID: 32866546 DOI: 10.1016/j.brainres.2020.147080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/31/2020] [Accepted: 08/21/2020] [Indexed: 01/01/2023]
Abstract
Glutamate (Glu) is the main mammalian brain neurotransmitter. Concerning the glutamatergic neurotransmission, excessive levels of glutamate in the synaptic cleft are extremally harmful. This phenomenon, named as excitotoxicity is involved in various acute and chronic brain diseases. Guanosine (GUO), an endogenous guanine nucleoside, possesses neuroprotective effects in several experimental models of glutamatergic excitotoxicity, an effect accompanied by an increase in astrocytic glutamate uptake. Therefore, the objective of this study was to investigate the involvement of an additional putative parameter, glutamate oxidation to CO2, involved in ex-vivo GUO neuroprotective effects in mouse hippocampal slices submitted to glutamatergic excitotoxicity. Mice were sacrificed by decapitation, the hippocampi were removed and sliced. The slices were incubated for various times and concentrations of Glu and GUO. First, the concentration of Glu that produced an increase in L-[14C(U)]-Glu oxidation to CO2 without cell injury was determined at different time points (between 0 and 90 min); 1000 μM Glu increased Glu oxidation between 30 and 60 min of incubation without cell injury. Under these conditions (Glu concentration and incubation time), 100 μM GUO increased Glu oxidation (35%). Additionally, 100 μM GUO increased L-[3,4-3H]-glutamate uptake (45%) in slices incubated with 1000 μM Glu (0-30 min). Furthermore, 1000 μM Glu increased reactive species levels, SOD activity, and decreased GPx activity, and GSH content after 30 and 60 min; 100 μM GUO prevented these effects. This is the first study demonstrating that GUO simultaneously promoted an increase in the uptake and utilization of Glu in excitotoxicity-like conditions preventing redox imbalance.
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Affiliation(s)
- Y Nonose
- Graduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil
| | - L Z Pieper
- Graduate Program in Health and Behavior, Center of Health Science, Universidade Católica de Pelotas - UCPel, Pelotas, RS 96015-560, Brazil
| | - J S da Silva
- Graduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil
| | - A Longoni
- Graduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil; Graduate Program in Health and Behavior, Center of Health Science, Universidade Católica de Pelotas - UCPel, Pelotas, RS 96015-560, Brazil
| | - R V Apel
- Graduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil
| | - L A Meira-Martins
- Graduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil
| | - M Grings
- Graduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil
| | - G Leipnitz
- Graduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil; Department of Biochemistry, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil
| | - D O Souza
- Graduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil; Department of Biochemistry, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil.
| | - A M de Assis
- Graduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS 90035-003, Brazil; Graduate Program in Health and Behavior, Center of Health Science, Universidade Católica de Pelotas - UCPel, Pelotas, RS 96015-560, Brazil
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10
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Marques EP, Ferreira FS, Santos TM, Prezzi CA, Martins LAM, Bobermin LD, Quincozes-Santos A, Wyse ATS. Cross-talk between guanidinoacetate neurotoxicity, memory and possible neuroprotective role of creatine. Biochim Biophys Acta Mol Basis Dis 2019; 1865:165529. [PMID: 31398469 DOI: 10.1016/j.bbadis.2019.08.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/21/2019] [Accepted: 08/05/2019] [Indexed: 12/18/2022]
Abstract
Guanidinoacetate Methyltransferase deficiency is an inborn error of metabolism that results in decreased creatine and increased guanidinoacetate (GAA) levels. Patients present neurological symptoms whose mechanisms are unclear. We investigated the effects of an intrastriatal administration of 10 μM of GAA (0.02 nmol/striatum) on energy metabolism, redox state, inflammation, glutamate homeostasis, and activities/immunocontents of acetylcholinesterase and Na+,K+-ATPase, as well as on memory acquisition. The neuroprotective role of creatine was also investigated. Male Wistar rats were pretreated with creatine (50 mg/kg) or saline for 7 days underwenting stereotactic surgery. Forty-eight hours after surgery, the animals (then sixty-days-old) were divided into groups: Control, GAA, GAA + Creatine, and Creatine. Experiments were performed 30 min after intrastriatal infusion. GAA decreased SDH, complexes II and IV activities, and ATP levels, but had no effect on mitochondrial mass/membrane potential. Creatine totally prevented SDH and complex II, and partially prevented COX and ATP alterations. GAA increased dichlorofluorescein levels and decreased superoxide dismutase and catalase activities. Creatine only prevented catalase and dichlorofluorescein alterations. GAA increased cytokines, nitrites levels and acetylcholinesterase activity, but not its immunocontent. Creatine prevented such effects, except nitrite levels. GAA decreased glutamate uptake, but had no effect on the immunocontent of its transporters. GAA decreased Na+,K+-ATPase activity and increased the immunocontent of its α3 subunit. The performance on the novel object recognition task was also impaired. Creatine partially prevented the changes in glutamate uptake and Na+,K+-ATPase activity, and completely prevented the memory impairment. This study helps to elucidate the protective effects of creatine against the damage caused by GAA.
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Affiliation(s)
- Eduardo Peil Marques
- Laboratory of Neuroprotection and Neurometabolic Diseases, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil; Program of Post-graduation in Biological Sciences-Biochemistry, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil
| | - Fernanda Silva Ferreira
- Laboratory of Neuroprotection and Neurometabolic Diseases, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil; Program of Post-graduation in Biological Sciences-Biochemistry, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil
| | - Tiago Marcon Santos
- Laboratory of Neuroprotection and Neurometabolic Diseases, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil; Program of Post-graduation in Biological Sciences-Biochemistry, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil
| | - Caroline Acauan Prezzi
- Laboratory of Neuroprotection and Neurometabolic Diseases, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil; Program of Post-graduation in Biological Sciences-Biochemistry, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil
| | - Leo A M Martins
- Program of Post-graduation in Biological Sciences-Biochemistry, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil
| | - Larissa Daniele Bobermin
- Program of Post-graduation in Biological Sciences-Biochemistry, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil
| | - André Quincozes-Santos
- Program of Post-graduation in Biological Sciences-Biochemistry, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil
| | - Angela T S Wyse
- Laboratory of Neuroprotection and Neurometabolic Diseases, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil; Program of Post-graduation in Biological Sciences-Biochemistry, Biochemistry Department, ICBS, Universidade Federal do Rio Grande do Sul, Street Ramiro Barcelos, 2600-Annex, CEP 90035-003 Porto Alegre, RS, Brazil.
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11
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Jackson EK, Mi Z, Janesko-Feldman K, Jackson TC, Kochanek PM. 2',3'-cGMP exists in vivo and comprises a 2',3'-cGMP-guanosine pathway. Am J Physiol Regul Integr Comp Physiol 2019; 316:R783-R790. [PMID: 30789788 PMCID: PMC6620655 DOI: 10.1152/ajpregu.00401.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 02/11/2019] [Accepted: 02/19/2019] [Indexed: 01/10/2023]
Abstract
The discovery in 2009 that 2',3'-cAMP exists in biological systems was rapidly followed by identification of 2',3'-cGMP in cell and tissue extracts. To determine whether 2',3'-cGMP exists in mammals under physiological conditions, we used ultraperformance LC-MS/MS to measure 2',3'-cAMP and 2',3'-cGMP in timed urine collections (via direct bladder cannulation) from 25 anesthetized mice. Urinary excretion rates (means ± SE) of 2',3'-cAMP (15.5 ± 1.8 ng/30 min) and 2',3'-cGMP (17.9 ± 1.9 ng/30 min) were similar. Mice also excreted 2'-AMP (3.6 ± 1.1 ng/20 min) and 3'-AMP (9.5 ± 1.2 ng/min), hydrolysis products of 2',3'-cAMP, and 2'-GMP (4.7 ± 1.7 ng/30 min) and 3'-GMP (12.5 ± 1.8 ng/30 min), hydrolysis products of 2',3'-cGMP. To validate that the chromatographic signals were from these endogenous noncanonical nucleotides, we repeated these experiments in mice (n = 18) lacking 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), an enzyme known to convert 2',3'-cyclic nucleotides to their corresponding 2'-nucleotides. In CNPase-knockout mice, urinary excretions of 2',3'-cAMP, 3'-AMP, 2',3'-cGMP, and 3'-GMP were increased, while urinary excretions of 2'-AMP and 2'-GMP were decreased. Infusions of exogenous 2',3'-cAMP increased urinary excretion of 2',3'-cAMP, 2'-AMP, 3'-AMP, and adenosine, whereas infusions of exogenous 2',3'-cGMP increased excretion of 2',3'-cGMP, 2'-GMP, 3'-GMP, and guanosine. Together, these data suggest the endogenous existence of not only a 2',3'-cAMP-adenosine pathway (2',3'-cAMP → 2'-AMP/3'-AMP → adenosine), which was previously identified, but also a 2',3'-cGMP-guanosine pathway (2',3'-cGMP → 2'-GMP/3'-GMP → guanosine), observed here for the first time. Because it is well known that adenosine and guanosine protect tissues from injury, our data support the concept that both pathways may work together to protect tissues from injury.
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Affiliation(s)
- Edwin K Jackson
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania
| | - Zaichuan Mi
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania
| | - Keri Janesko-Feldman
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania
| | - Travis C Jackson
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania
| | - Patrick M Kochanek
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania
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12
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Cryan MT, Ross AE. Scalene Waveform for Codetection of Guanosine and Adenosine Using Fast-Scan Cyclic Voltammetry. Anal Chem 2019; 91:5987-5993. [DOI: 10.1021/acs.analchem.9b00450] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Michael T. Cryan
- Department of Chemistry, University of Cincinnati, 312 College Drive, 404 Crosley Tower, Cincinnati, Ohio 45221-0172, United States
| | - Ashley E. Ross
- Department of Chemistry, University of Cincinnati, 312 College Drive, 404 Crosley Tower, Cincinnati, Ohio 45221-0172, United States
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13
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Cryan MT, Ross AE. Subsecond detection of guanosine using fast-scan cyclic voltammetry. Analyst 2019; 144:249-257. [PMID: 30484441 DOI: 10.1039/c8an01547c] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Guanosine is an important neuromodulator and neuroprotector in the brain and is involved in many pathological conditions, including ischemia and neuroinflammation. Traditional methods to detect guanosine in the brain, like HPLC, offer low limits of detection and are robust; however, subsecond detection is not possible. Here, we present a method for detecting rapid fluctuations of guanosine concentration in real-time using fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes. The optimized waveform scanned from -0.4 V to 1.3 V and back at a rate of 400 V s-1 and application frequency of 10 Hz. Potential limits were chosen to increase selectivity of guanosine over the structurally similar interferent adenosine. Two oxidation peaks were detected with the optimized waveform: the primary oxidation reaction occurred at 1.3 V and the secondary oxidation at 0.8 V. Guanosine detection was stable over time with a limit of detection of 30 ± 10 nM, which permits its use to monitor low nanomolar fluctuations in the brain. To demonstrate the feasibility of the method for in-tissue detection, guanosine was exogenously applied and detected within live rat brain slices. This paper demonstrates the first characterization of guanosine using FSCV, and will be a valuable method for measuring signaling dynamics during guanosine neuromodulation and protection.
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Affiliation(s)
- Michael T Cryan
- University of Cincinnati, Department of Chemistry, 312 College Dr., 404 Crosley Tower, Cincinnati, OH 45221-0172, USA.
| | - Ashley E Ross
- University of Cincinnati, Department of Chemistry, 312 College Dr., 404 Crosley Tower, Cincinnati, OH 45221-0172, USA.
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14
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Neves J, Vizuete A, Nicola F, Da Ré C, Rodrigues A, Schmitz F, Mestriner R, Aristimunha D, Wyse A, Netto C. Glial glutamate transporters expression, glutamate uptake, and oxidative stress in an experimental rat model of intracerebral hemorrhage. Neurochem Int 2018. [DOI: 10.1016/j.neuint.2018.03.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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15
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Teixeira LV, Almeida RF, Rohden F, Martins LAM, Spritzer PM, de Souza DOG. Neuroprotective Effects of Guanosine Administration on In Vivo Cortical Focal Ischemia in Female and Male Wistar Rats. Neurochem Res 2018; 43:1476-1489. [PMID: 29855847 DOI: 10.1007/s11064-018-2562-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 05/23/2018] [Accepted: 05/26/2018] [Indexed: 02/07/2023]
Abstract
Guanosine (GUO) has neuroprotective effects in experimental models of brain diseases involving glutamatergic excitotoxicity in male animals; however, its effects in female animals are poorly understood. Thus, we investigated the influence of gender and GUO treatment in adult male and female Wistar rats submitted to focal permanent cerebral ischemia in the motor cortex brain. Female rats were subdivided into non-estrogenic and estrogenic phase groups by estrous cycle verification. Immediately after surgeries, the ischemic animals were treated with GUO or a saline solution. Open field and elevated plus maze tasks were conducted with ischemic and naïve animals. Cylinder task, immunohistochemistry and infarct volume analyses were conducted only with ischemic animals. Female GUO groups achieved a full recovery of the forelimb symmetry at 28-35 days after the insult, while male GUO groups only partially recovered at 42 days, in the final evaluation. The ischemic insult affected long-term memory habituation to novelty only in female groups. Anxiety-like behavior, astrocyte morphology and infarct volume were not affected. Regardless the estrous cycle, the ischemic injury affected differently female and male animals. Thus, this study points that GUO is a potential neuroprotective compound in experimental stroke and that more studies, considering the estrous cycle, with both genders are recommended in future investigation concerning brain diseases.
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Affiliation(s)
- Luciele Varaschini Teixeira
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
| | - Roberto Farina Almeida
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Francieli Rohden
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Leo Anderson Meira Martins
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Poli Mara Spritzer
- Department of Physiology, Laboratory of Molecular Endocrinology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Diogo Onofre Gomes de Souza
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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16
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Shaidarova LG, Gedmina AV, Demina VD, Chelnokova IA, Budnikov HC. Selective Voltammetric and Flow-Injection Determination of Guanosine and Adenosine at a Glassy Carbon Electrode Modified with a Ruthenium Hexachlororuthenate Film. JOURNAL OF ANALYTICAL CHEMISTRY 2018. [DOI: 10.1134/s1061934818040111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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α-Ketoadipic Acid and α-Aminoadipic Acid Cause Disturbance of Glutamatergic Neurotransmission and Induction of Oxidative Stress In Vitro in Brain of Adolescent Rats. Neurotox Res 2017; 32:276-290. [DOI: 10.1007/s12640-017-9735-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 03/30/2017] [Accepted: 04/05/2017] [Indexed: 12/21/2022]
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18
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Dobrachinski F, da Rosa Gerbatin R, Sartori G, Ferreira Marques N, Zemolin AP, Almeida Silva LF, Franco JL, Freire Royes LF, Rechia Fighera M, Antunes Soares FA. Regulation of Mitochondrial Function and Glutamatergic System Are the Target of Guanosine Effect in Traumatic Brain Injury. J Neurotrauma 2017; 34:1318-1328. [PMID: 27931151 DOI: 10.1089/neu.2016.4563] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Traumatic brain injury (TBI) is a highly complex multi-factorial disorder. Experimental trauma involves primary and secondary injury cascades that underlie delayed neuronal dysfunction and death. Mitochondrial dysfunction and glutamatergic excitotoxicity are the hallmark mechanisms of damage. Accordingly, a successful pharmacological intervention requires a multi-faceted approach. Guanosine (GUO) is known for its neuromodulator effects in various models of brain pathology, specifically those that involve the glutamatergic system. The aim of the study was to investigate the GUO effects against mitochondrial damage in hippocampus and cortex of rats subjected to TBI, as well as the relationship of this effect with the glutamatergic system. Adult male Wistar rats were subjected to a unilateral moderate fluid percussion brain injury (FPI) and treated 15 min later with GUO (7.5 mg/kg) or vehicle (saline 0.9%). Analyses were performed in hippocampus and cortex 3 h post-trauma and revealed significant mitochondrial dysfunction, characterized by a disrupted membrane potential, unbalanced redox system, decreased mitochondrial viability, and complex I inhibition. Further, disruption of Ca2+ homeostasis and increased mitochondrial swelling was also noted. Our results showed that mitochondrial dysfunction contributed to decreased glutamate uptake and levels of glial glutamate transporters (glutamate transporter 1 and glutamate aspartate transporter), which leads to excitotoxicity. GUO treatment ameliorated mitochondrial damage and glutamatergic dyshomeostasis. Thus, GUO might provide a new efficacious strategy for the treatment acute physiological alterations secondary to TBI.
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Affiliation(s)
- Fernando Dobrachinski
- 1 Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil .,5 CNC-Centro de Neurociências e Biologia Celular, Faculdade de Medicina, Universidade de Coimbra , Coimbra, Portugal
| | - Rogério da Rosa Gerbatin
- 1 Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil .,2 Laboratório de Bioquímica do Exercício, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil
| | - Gláubia Sartori
- 1 Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil
| | - Naiani Ferreira Marques
- 1 Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil
| | - Ana Paula Zemolin
- 1 Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil
| | - Luiz Fernando Almeida Silva
- 1 Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil
| | - Jeferson Luis Franco
- 1 Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil .,4 Programa de Pós-Graduação em Ciências Biológicas, Universidade Federal do Pampa , Campus São Gabriel, São Gabriel, RS, Brasil
| | - Luiz Fernando Freire Royes
- 1 Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil .,2 Laboratório de Bioquímica do Exercício, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil
| | - Michele Rechia Fighera
- 1 Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil .,3 Departamento de Neuropsiquiatria, Centro de Ciências da Saúde, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil
| | - Félix Alexandre Antunes Soares
- 1 Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria , Santa Maria, RS, Brasil
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19
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Sha L, Wang X, Li J, Shi X, Wu L, Shen Y, Xu Q. Pharmacologic inhibition of Hsp90 to prevent GLT-1 degradation as an effective therapy for epilepsy. J Exp Med 2016; 214:547-563. [PMID: 28028152 PMCID: PMC5294855 DOI: 10.1084/jem.20160667] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 10/11/2016] [Accepted: 12/13/2016] [Indexed: 12/12/2022] Open
Abstract
Sha et al. report that Hsp90β, which is up-regulated in astrocytes of human epileptogenic tissue, interacts with GLT-1 and recruits it to 20S proteasome for degradation. The Hsp90 inhibitor 17AAG exhibits beneficial effects in a model of temporal lobe epilepsy. The glutamate transporter GLT-1 is critical for the maintenance of low interstitial glutamate concentrations. Loss of GLT-1 is commonly observed in neurological disorders, including temporal lobe epilepsy (TLE). Despite the hypothesis that targeting the mechanisms of GLT-1 deficiency may be a novel strategy for treating drug-resistant epilepsy, the underlying molecular cascade remains largely unknown. Here, we show that Hsp90β is up-regulated in reactive astrocytes of the epileptic hippocampus in patients with TLE and mouse models of epilepsy. Inhibition of Hsp90, but not Hsp70, increased GLT-1 levels. Mechanistically, Hsp90β recruits GLT-1 to the 20S proteasome, thereby promoting GLT-1 degradation. Hsp90 inhibitor prevents GLT-1 degradation by disrupting the association between Hsp90β and GLT-1. Using a model of TLE, we demonstrated that long-term systemic administration of 17AAG dramatically suppressed spontaneous recurrent seizures and ameliorated astrogliosis. Overall, these results suggest that up-regulation of GLT-1 by inhibiting Hsp90β in reactive astrocytes may be a potential therapeutic target for the treatment of epilepsy and excitotoxicity.
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Affiliation(s)
- Longze Sha
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences and Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
| | - Xueqin Wang
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences and Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
| | - Jing Li
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences and Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
| | - Xinze Shi
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences and Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
| | - Liwen Wu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China
| | - Yan Shen
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences and Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
| | - Qi Xu
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences and Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
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20
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Schmitz F, Pierozan P, Rodrigues AF, Biasibetti H, Grings M, Zanotto B, Coelho DM, Vargas CR, Leipnitz G, Wyse ATS. Methylphenidate Decreases ATP Levels and Impairs Glutamate Uptake and Na +,K +-ATPase Activity in Juvenile Rat Hippocampus. Mol Neurobiol 2016; 54:7796-7807. [PMID: 27844288 DOI: 10.1007/s12035-016-0289-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 11/02/2016] [Indexed: 01/05/2023]
Abstract
The study of the long-term neurological consequences of early exposure with methylphenidate (MPH) is very important since this psychostimulant has been widely misused by children and adolescents who do not meet full diagnostic criteria for ADHD. The aim of this study was to examine the effect of early chronic exposure with MPH on amino acids profile, glutamatergic and Na+,K+-ATPase homeostasis, as well as redox and energy status in the hippocampus of juvenile rats. Wistar male rats received intraperitoneal injections of MPH (2.0 mg/kg) or saline solution (controls), once a day, from the 15th to the 45th day of age. Results showed that MPH altered amino acid profile in the hippocampus, decreasing glutamine levels. Glutamate uptake and Na+,K+-ATPase activity were decreased after chronic MPH exposure in the hippocampus of rats. No changes were observed in the immunocontents of glutamate transporters (GLAST and GLT-1), and catalytic subunits of Na+,K+-ATPase (α1, α2, and α3), as well as redox status. Moreover, MPH provoked a decrease in ATP levels in the hippocampus of chronically exposed rats, while citrate synthase, succinate dehydrogenase, respiratory chain complexes activities (II, II-III, and IV), as well as mitochondrial mass and mitochondrial membrane potential were not altered. Taken together, our results suggest that chronic MPH exposure at early age impairs glutamate uptake and Na+,K+-ATPase activity probably by decreasing in ATP levels observed in rat hippocampus.
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Affiliation(s)
- Felipe Schmitz
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Paula Pierozan
- Laboratório de Neuroproteção e Doenças Metabólicas, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - André F Rodrigues
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Helena Biasibetti
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Mateus Grings
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Bruna Zanotto
- Laboratório de Neuroproteção e Doenças Metabólicas, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Daniella M Coelho
- Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - Carmen R Vargas
- Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - Guilhian Leipnitz
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.,Laboratório de Neuroproteção e Doenças Metabólicas, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Angela T S Wyse
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. .,Laboratório de Neuroproteção e Doenças Metabólicas, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. .,Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, CEP 90035-003, Brazil.
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21
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Lanznaster D, Dal-Cim T, Piermartiri TCB, Tasca CI. Guanosine: a Neuromodulator with Therapeutic Potential in Brain Disorders. Aging Dis 2016; 7:657-679. [PMID: 27699087 PMCID: PMC5036959 DOI: 10.14336/ad.2016.0208] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 02/08/2016] [Indexed: 12/20/2022] Open
Abstract
Guanosine is a purine nucleoside with important functions in cell metabolism and a protective role in response to degenerative diseases or injury. The past decade has seen major advances in identifying the modulatory role of extracellular action of guanosine in the central nervous system (CNS). Evidence from rodent and cell models show a number of neurotrophic and neuroprotective effects of guanosine preventing deleterious consequences of seizures, spinal cord injury, pain, mood disorders and aging-related diseases, such as ischemia, Parkinson’s and Alzheimer’s diseases. The present review describes the findings of in vivo and in vitro studies and offers an update of guanosine effects in the CNS. We address the protein targets for guanosine action and its interaction with glutamatergic and adenosinergic systems and with calcium-activated potassium channels. We also discuss the intracellular mechanisms modulated by guanosine preventing oxidative damage, mitochondrial dysfunction, inflammatory burden and modulation of glutamate transport. New and exciting avenues for future investigation into the protective effects of guanosine include characterization of a selective guanosine receptor. A better understanding of the neuromodulatory action of guanosine will allow the development of therapeutic approach to brain diseases.
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Affiliation(s)
- Débora Lanznaster
- 2Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina-UFSC, Campus Trindade, 88040-900, Florianópolis, SC, Brazil; 3CAPES Foundation, Ministry of Education of Brazil, Brasília - DF 70040-020, Brazil
| | - Tharine Dal-Cim
- 2Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina-UFSC, Campus Trindade, 88040-900, Florianópolis, SC, Brazil; 3CAPES Foundation, Ministry of Education of Brazil, Brasília - DF 70040-020, Brazil
| | - Tetsadê C B Piermartiri
- 2Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina-UFSC, Campus Trindade, 88040-900, Florianópolis, SC, Brazil; 3CAPES Foundation, Ministry of Education of Brazil, Brasília - DF 70040-020, Brazil
| | - Carla I Tasca
- 1Departamento de Bioquímica,; 2Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina-UFSC, Campus Trindade, 88040-900, Florianópolis, SC, Brazil
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22
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Pierozan P, Biasibetti H, Schmitz F, Ávila H, Fernandes CG, Pessoa-Pureur R, Wyse ATS. Neurotoxicity of Methylmercury in Isolated Astrocytes and Neurons: the Cytoskeleton as a Main Target. Mol Neurobiol 2016; 54:5752-5767. [DOI: 10.1007/s12035-016-0101-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 09/05/2016] [Indexed: 01/16/2023]
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Bettio LEB, Gil-Mohapel J, Rodrigues ALS. Guanosine and its role in neuropathologies. Purinergic Signal 2016; 12:411-26. [PMID: 27002712 PMCID: PMC5023624 DOI: 10.1007/s11302-016-9509-4] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 03/08/2016] [Indexed: 02/08/2023] Open
Abstract
Guanosine is a purine nucleoside thought to have neuroprotective properties. It is released in the brain under physiological conditions and even more during pathological events, reducing neuroinflammation, oxidative stress, and excitotoxicity, as well as exerting trophic effects in neuronal and glial cells. In agreement, guanosine was shown to be protective in several in vitro and/or in vivo experimental models of central nervous system (CNS) diseases including ischemic stroke, Alzheimer's disease, Parkinson's disease, spinal cord injury, nociception, and depression. The mechanisms underlying the neurobiological properties of guanosine seem to involve the activation of several intracellular signaling pathways and a close interaction with the adenosinergic system, with a consequent stimulation of neuroprotective and regenerative processes in the CNS. Within this context, the present review will provide an overview of the current literature on the effects of guanosine in the CNS. The elucidation of the complex signaling events underlying the biochemical and cellular effects of this nucleoside may further establish guanosine as a potential therapeutic target for the treatment of several neuropathologies.
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Affiliation(s)
- Luis E B Bettio
- Department of Biochemistry, Center of Biological Sciences, Federal University of Santa Catarina, 88040-900, Florianópolis, SC, Brazil
- Division of Medical Sciences and UBC Island Medical Program, University of Victoria, Victoria, BC, V8W 2Y2, Canada
| | - Joana Gil-Mohapel
- Division of Medical Sciences and UBC Island Medical Program, University of Victoria, Victoria, BC, V8W 2Y2, Canada
| | - Ana Lúcia S Rodrigues
- Department of Biochemistry, Center of Biological Sciences, Federal University of Santa Catarina, 88040-900, Florianópolis, SC, Brazil.
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da Silva Fiorin F, de Oliveira Ferreira AP, Ribeiro LR, Silva LFA, de Castro MRT, da Silva LRH, da Silveira MEP, Zemolin APP, Dobrachinski F, Marchesan de Oliveira S, Franco JL, Soares FA, Furian AF, Oliveira MS, Fighera MR, Freire Royes LF. The Impact of Previous Physical Training on Redox Signaling after Traumatic Brain Injury in Rats: A Behavioral and Neurochemical Approach. J Neurotrauma 2016; 33:1317-30. [PMID: 26651029 DOI: 10.1089/neu.2015.4068] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Throughout the world, traumatic brain injury (TBI) is one of the major causes of disability, which can include deficits in motor function and memory, as well as acquired epilepsy. Although some studies have shown the beneficial effects of physical exercise after TBI, the prophylactic effects are poorly understood. In the current study, we demonstrated that TBI induced by fluid percussion injury (FPI) in adult male Wistar rats caused early motor impairment (24 h), learning deficit (15 days), spontaneous epileptiform events (SEE), and hilar cell loss in the hippocampus (35 days) after TBI. The hippocampal alterations in the redox status, which were characterized by dichlorofluorescein diacetate oxidation and superoxide dismutase (SOD) activity inhibition, led to the impairment of protein function (Na(+), K(+)-adenosine triphosphatase [ATPase] activity inhibition) and glutamate uptake inhibition 24 h after neuronal injury. The molecular adaptations elicited by previous swim training protected against the glutamate uptake inhibition, oxidative stress, and inhibition of selected targets for free radicals (e.g., Na(+), K(+)-ATPase) 24 h after neuronal injury. Our data indicate that this protocol of exercise protected against FPI-induced motor impairment, learning deficits, and SEE. In addition, the enhancement of the hippocampal phosphorylated nuclear factor erythroid 2-related factor (P-Nrf2)/Nrf2, heat shock protein 70, and brain-derived neurotrophic factor immune content in the trained injured rats suggests that protein expression modulation associated with an antioxidant defense elicited by previous physical exercise can prevent toxicity induced by TBI, which is characterized by cell loss in the dentate gyrus hilus at 35 days after TBI. Therefore, this report suggests that previous physical exercise can decrease lesion progression in this model of brain damage.
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Affiliation(s)
- Fernando da Silva Fiorin
- 1 Laboratório de Bioquímica do Exercício, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | | | - Leandro R Ribeiro
- 1 Laboratório de Bioquímica do Exercício, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Luiz F A Silva
- 1 Laboratório de Bioquímica do Exercício, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Mauro R T de Castro
- 1 Laboratório de Bioquímica do Exercício, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Luís R H da Silva
- 1 Laboratório de Bioquímica do Exercício, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Mauro E P da Silveira
- 1 Laboratório de Bioquímica do Exercício, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Ana P P Zemolin
- 2 Programa de Pós-Graduação em Ciências Biológicas, Bioquímica Toxicológica, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Fernando Dobrachinski
- 2 Programa de Pós-Graduação em Ciências Biológicas, Bioquímica Toxicológica, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Sara Marchesan de Oliveira
- 2 Programa de Pós-Graduação em Ciências Biológicas, Bioquímica Toxicológica, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Jeferson L Franco
- 2 Programa de Pós-Graduação em Ciências Biológicas, Bioquímica Toxicológica, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Félix A Soares
- 2 Programa de Pós-Graduação em Ciências Biológicas, Bioquímica Toxicológica, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Ana F Furian
- 3 Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Mauro S Oliveira
- 3 Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Michele R Fighera
- 1 Laboratório de Bioquímica do Exercício, Universidade Federal de Santa Maria , Santa Maria, Brazil .,2 Programa de Pós-Graduação em Ciências Biológicas, Bioquímica Toxicológica, Universidade Federal de Santa Maria , Santa Maria, Brazil .,3 Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria , Santa Maria, Brazil
| | - Luiz F Freire Royes
- 1 Laboratório de Bioquímica do Exercício, Universidade Federal de Santa Maria , Santa Maria, Brazil .,2 Programa de Pós-Graduação em Ciências Biológicas, Bioquímica Toxicológica, Universidade Federal de Santa Maria , Santa Maria, Brazil .,3 Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria , Santa Maria, Brazil
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Deletion of mTOR in Reactive Astrocytes Suppresses Chronic Seizures in a Mouse Model of Temporal Lobe Epilepsy. Mol Neurobiol 2016; 54:175-187. [PMID: 26732600 DOI: 10.1007/s12035-015-9590-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 11/29/2015] [Indexed: 01/28/2023]
Abstract
Germline and somatic mutations in key genes of the mammalian target of rapamycin (mTOR) pathway have been identified in seizure-associated disorders. mTOR mutations lead to aberrant activation of mTOR signaling, and, although affected neurons are critical for epileptogenesis, the role of mTOR activation in glial cells remains poorly understood. We previously reported a consistent activation of the mTOR pathway in astrocytes in the epileptic foci of temporal lobe epilepsy. In this study, it was demonstrated that mTOR deletion from reactive astrocytes prevents increases in seizure frequency over the disease course. By using a tamoxifen-inducible mTOR conditional knockout system and kainic acid, a model was developed that allowed astrocyte-specific mTOR gene deletion in mice with chronic epilepsy. Animals in which mTOR was deleted from 44 % of the astrocyte population exhibited a lower seizure frequency compared with controls. Down-regulation of mTOR significantly ameliorated astrogliosis in the sclerotic hippocampus but did not rescue mossy fiber sprouting. In cultured astrocytes, the mTOR pathway modulated the stability of the astroglial glutamate transporter 1 (Glt1) and influenced the ability of astrocytes to remove extracellular glutamate. Taken together, these data indicate that astrocytes with activated mTOR signaling may provide conditions that are favorable for spontaneous recurrent seizures.
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de Oliveira ED, Schallenberger C, Böhmer AE, Hansel G, Fagundes AC, Milman M, Silva MDP, Oses JP, Porciúncula LO, Portela LV, Elisabetsky E, Souza DO, Schmidt AP. Mechanisms involved in the antinociception induced by spinal administration of inosine or guanine in mice. Eur J Pharmacol 2015; 772:71-82. [PMID: 26712379 DOI: 10.1016/j.ejphar.2015.12.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Revised: 12/17/2015] [Accepted: 12/18/2015] [Indexed: 11/27/2022]
Abstract
It is well known that adenine-based purines exert multiple effects on pain transmission. Recently, we have demonstrated that guanine-based purines may produce some antinociceptive effects against chemical and thermal pain in mice. The present study was designed to investigate the antinociceptive effects of intrathecal (i.t.) administration of inosine or guanine in mice. Additionally, investigation into the mechanisms of action of these purines, their general toxicity and measurements of CSF purine levels were performed. Animals received an i.t. injection of vehicle (30mN NaOH), inosine or guanine (up to 600nmol) and submitted to several pain models and behavioural paradigms. Guanine and inosine produced dose-dependent antinociceptive effects in the tail-flick, hot-plate, intraplantar (i.pl.) glutamate, i.pl. capsaicin and acetic acid pain models. Additionally, i.t. inosine inhibited the biting behaviour induced by spinal injection of capsaicin and i.t. guanine reduced the biting behaviour induced by spinal injection of glutamate or AMPA. Intrathecal administration of inosine (200nmol) induced an approximately 115-fold increase on CSF inosine levels. This study provides new evidence on the mechanism of action of extracellular guanine and inosine presenting antinociceptive effects following spinal administration. These effects seem to be related, at least partially, to the modulation of A1 adenosine receptors.
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Affiliation(s)
- Enderson D de Oliveira
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Cristhine Schallenberger
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Ana Elisa Böhmer
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Gisele Hansel
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Aécio C Fagundes
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Michael Milman
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Marcos D P Silva
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Jean P Oses
- Programa de Pós-graduação em Saúde e Comportamento, Centro de Ciências da Vida e da Saúde e Hospital Universitário São Francisco de Paula, Universidade Católica de Pelotas, Pelotas, RS, Brazil
| | - Lisiane O Porciúncula
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Luís V Portela
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Elaine Elisabetsky
- Department of Pharmacology, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Diogo O Souza
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - André P Schmidt
- Department of Biochemistry, Institute of Health Sciences (ICBS), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Department of Anaesthesia and Perioperative Medicine, Hospital de Clínicas de Porto Alegre (HCPA), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Division of Anaesthesia, Department of Surgery, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil.
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27
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Priftis D. Polyelectrolyte-graphene Nanocomposites for Biosensing Applications. CURR ORG CHEM 2015; 19:1819-1827. [PMID: 27713667 PMCID: PMC5024728 DOI: 10.2174/1385272819666150526005557] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 03/05/2015] [Accepted: 05/25/2015] [Indexed: 11/22/2022]
Abstract
Due to their unique structure, the optical and mechanical properties graphene and its derivatives (e.g. graphene oxide, reduced graphene oxide) have captured the attention of a constantly increasing number of scientists with regards to biomolecule sensing. This mini review focuses on one specific type of sensor, that consisting of graphene and polyelectrolytes. Polyelectrolyte-graphene nanocomposites exhibit outstanding detection capabilities by synergistically combining the characteristics of both components, outperforming traditional sensors in many cases. Characteristics and mechanistic details of the most important polyelectrolyte-graphene based sensors will be discussed in detail in addition to some current challenges and future perspectives.
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Affiliation(s)
- Dimitrios Priftis
- The Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637,USA
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28
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Schmitz F, Pierozan P, Rodrigues AF, Biasibetti H, Coelho DM, Mussulini BH, Pereira MSL, Parisi MM, Barbé-Tuana F, de Oliveira DL, Vargas CR, Wyse ATS. Chronic Treatment with a Clinically Relevant Dose of Methylphenidate Increases Glutamate Levels in Cerebrospinal Fluid and Impairs Glutamatergic Homeostasis in Prefrontal Cortex of Juvenile Rats. Mol Neurobiol 2015; 53:2384-96. [PMID: 26001762 DOI: 10.1007/s12035-015-9219-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 05/12/2015] [Indexed: 12/27/2022]
Abstract
The understanding of the consequences of chronic treatment with methylphenidate is very important since this psychostimulant is extensively prescribed to preschool age children, and little is known about the mechanisms underlying the persistent changes in behavior and neuronal function related with the use of methylphenidate. In this study, we initially investigate the effect of early chronic treatment with methylphenidate on amino acids profile in cerebrospinal fluid and prefrontal cortex of juvenile rats, as well as on glutamatergic homeostasis, Na(+),K(+)-ATPase function, and balance redox in prefrontal cortex of rats. Wistar rats at early age received intraperitoneal injections of methylphenidate (2.0 mg/kg) or an equivalent volume of 0.9% saline solution (controls), once a day, from the 15th to the 45th day of age. Twenty-four hours after the last injection, the animals were decapitated and the cerebrospinal fluid and prefrontal cortex were obtained. Results showed that methylphenidate altered amino acid profile in cerebrospinal fluid, increasing the levels of glutamate. Glutamate uptake was decreased by methylphenidate administration, but GLAST and GLT-1 were not altered by this treatment. In addition, the astrocyte marker GFAP was not altered by MPH. The activity and immunocontent of catalytic subunits (α1, α2, and α3) of Na(+),K(+)-ATPase were decreased in prefrontal cortex of rats subjected to methylphenidate treatment, as well as changes in α1 and α2 gene expression of catalytic α subunits of Na(+),K(+)-ATPase were also observed. CAT activity was increased and SOD/CAT ratio and sulfhydryl content were decreased in rat prefrontal cortex. Taken together, our results suggest that chronic treatment with methylphenidate at early age induces excitotoxicity, at least in part, due to inhibition of glutamate uptake probably caused by disturbances in the Na(+),K(+)-ATPase function and/or in protein damage observed in the prefrontal cortex.
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Affiliation(s)
- Felipe Schmitz
- Laboratório de Neuroproteção e Doenças Metabólicas, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, Porto Alegre, RS, Brazil
| | - Paula Pierozan
- Laboratório de Neuroproteção e Doenças Metabólicas, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, Porto Alegre, RS, Brazil
| | - André F Rodrigues
- Laboratório de Neuroproteção e Doenças Metabólicas, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, Porto Alegre, RS, Brazil
| | - Helena Biasibetti
- Laboratório de Neuroproteção e Doenças Metabólicas, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, Porto Alegre, RS, Brazil
| | - Daniella M Coelho
- Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - Ben Hur Mussulini
- Laboratório de Sinalização Glutamatérgica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Mery S L Pereira
- Laboratório de Sinalização Glutamatérgica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Mariana M Parisi
- Laboratório de Biologia Molecular, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Florencia Barbé-Tuana
- Laboratório de Biologia Molecular, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Diogo L de Oliveira
- Laboratório de Sinalização Glutamatérgica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Carmen R Vargas
- Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - Angela T S Wyse
- Laboratório de Neuroproteção e Doenças Metabólicas, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, Porto Alegre, RS, Brazil.
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29
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Parmeggiani B, Moura AP, Grings M, Bumbel AP, Moura Alvorcem L, Tauana Pletsch J, Fernandes CG, Wyse ATS, Wajner M, Leipnitz G. In vitro
evidence that sulfite impairs glutamatergic neurotransmission and inhibits glutathione metabolism‐related enzymes in rat cerebral cortex. Int J Dev Neurosci 2015; 42:68-75. [DOI: 10.1016/j.ijdevneu.2015.03.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/11/2015] [Accepted: 03/11/2015] [Indexed: 11/15/2022] Open
Affiliation(s)
- Belisa Parmeggiani
- Departamento de BioquímicaInstituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do SulRua Ramiro Barcelos, 2600 – Anexo – CEP90035‐003Porto AlegreRSBrazil
| | - Alana Pimentel Moura
- Departamento de BioquímicaInstituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do SulRua Ramiro Barcelos, 2600 – Anexo – CEP90035‐003Porto AlegreRSBrazil
| | - Mateus Grings
- Departamento de BioquímicaInstituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do SulRua Ramiro Barcelos, 2600 – Anexo – CEP90035‐003Porto AlegreRSBrazil
| | - Anna Paula Bumbel
- Departamento de BioquímicaInstituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do SulRua Ramiro Barcelos, 2600 – Anexo – CEP90035‐003Porto AlegreRSBrazil
| | - Leonardo Moura Alvorcem
- Departamento de BioquímicaInstituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do SulRua Ramiro Barcelos, 2600 – Anexo – CEP90035‐003Porto AlegreRSBrazil
| | - Julia Tauana Pletsch
- Departamento de BioquímicaInstituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do SulRua Ramiro Barcelos, 2600 – Anexo – CEP90035‐003Porto AlegreRSBrazil
| | - Carolina Gonçalves Fernandes
- Departamento de BioquímicaInstituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do SulRua Ramiro Barcelos, 2600 – Anexo – CEP90035‐003Porto AlegreRSBrazil
| | - Angela TS Wyse
- Departamento de BioquímicaInstituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do SulRua Ramiro Barcelos, 2600 – Anexo – CEP90035‐003Porto AlegreRSBrazil
| | - Moacir Wajner
- Departamento de BioquímicaInstituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do SulRua Ramiro Barcelos, 2600 – Anexo – CEP90035‐003Porto AlegreRSBrazil
- Serviço de Genética MédicaHospital de Clínicas de Porto AlegreRua Ramiro Barcelos, 2350 – CEP90035‐003Porto AlegreRSBrazil
| | - Guilhian Leipnitz
- Departamento de BioquímicaInstituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do SulRua Ramiro Barcelos, 2600 – Anexo – CEP90035‐003Porto AlegreRSBrazil
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30
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Shi F, Wang X, Wang W, Sun W. Electrochemical behavior and determination of guanosine-5′-monophosphate on a ionic liquid modified carbon electrode. JOURNAL OF ANALYTICAL CHEMISTRY 2015. [DOI: 10.1134/s1061934815020057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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31
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Busanello ENB, Fernandes CG, Martell RV, Lobato VGA, Goodman S, Woontner M, de Souza DOG, Wajner M. Disturbance of the glutamatergic system by glutaric acid in striatum and cerebral cortex of glutaryl-CoA dehydrogenase-deficient knockout mice: Possible implications for the neuropathology of glutaric acidemia type I. J Neurol Sci 2014; 346:260-7. [DOI: 10.1016/j.jns.2014.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 08/21/2014] [Accepted: 09/03/2014] [Indexed: 11/30/2022]
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Guanosine prevents behavioral alterations in the forced swimming test and hippocampal oxidative damage induced by acute restraint stress. Pharmacol Biochem Behav 2014; 127:7-14. [PMID: 25316306 DOI: 10.1016/j.pbb.2014.10.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 09/19/2014] [Accepted: 10/05/2014] [Indexed: 11/23/2022]
Abstract
Guanosine is a guanine-based purine that modulates glutamate uptake and exerts neurotrophic and neuroprotective effects. In a previous study, our group demonstrated that this endogenous nucleoside displays antidepressant-like properties in a predictive animal model. Based on the role of oxidative stress in modulating depressive disorders as well as on the association between the neuroprotective and antioxidant properties of guanosine, here we investigated if its antidepressant-like effect is accompanied by a modulation of hippocampal oxidant/antioxidant parameters. Adult Swiss mice were submitted to an acute restraint stress protocol, which is known to cause behavioral changes that are associated with neuronal oxidative damage. Animals submitted to ARS exhibited an increased immobility time in the forced swimming test (FST) and the administration of guanosine (5mg/kg, p.o.) or fluoxetine (10mg/kg, p.o., positive control) before the exposure to stressor prevented this alteration. Moreover, the significantly increased levels of hippocampal malondialdehyde (MDA; an indicator of lipid peroxidation), induced by ARS were not observed in stressed mice treated with guanosine. Although no changes were found in the hippocampal levels of reduced glutathione (GSH), the group submitted to ARS procedure presented enhanced glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) activities and reduced catalase (CAT) activity in the hippocampus. Guanosine was able to prevent the alterations in GPx, GR, CAT activities, and in SOD/CAT activity ratio, but potentiated the increase in SOD activity elicited by ARS. Altogether, the present findings indicate that the observed antidepressant-like effects of guanosine might be related, at least in part, to its capability of modulating antioxidant defenses and mitigating hippocampal oxidative damage induced by ARS.
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Pierozan P, Fernandes CG, Dutra MF, Pandolfo P, Ferreira F, de Lima BO, Porciúncula L, Wajner M, Pessoa-Pureur R. Biochemical, histopathological and behavioral alterations caused by intrastriatal administration of quinolic acid to young rats. FEBS J 2014; 281:2061-73. [DOI: 10.1111/febs.12762] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 02/03/2014] [Accepted: 02/19/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Paula Pierozan
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde; UFRGS; Porto Alegre RS Brasil
| | - Carolina G. Fernandes
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde; UFRGS; Porto Alegre RS Brasil
| | - Márcio F. Dutra
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde; UFRGS; Porto Alegre RS Brasil
- Departamento de Biologia Celular, Embriologia e Genética; Centro Ciências Biológicas; Universidade Federal de Santa Catarina; Florianópolis SC Brasil
| | - Pablo Pandolfo
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde; UFRGS; Porto Alegre RS Brasil
- Departamento de Neurobiologia; Instituto de Biologia; Universidade Federal Fluminense; Niterói RJ Brasil
| | - Fernanda Ferreira
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde; UFRGS; Porto Alegre RS Brasil
| | - Bárbara O. de Lima
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde; UFRGS; Porto Alegre RS Brasil
| | - Lisiane Porciúncula
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde; UFRGS; Porto Alegre RS Brasil
| | - Moacir Wajner
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde; UFRGS; Porto Alegre RS Brasil
| | - Regina Pessoa-Pureur
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde; UFRGS; Porto Alegre RS Brasil
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Sun W, Wang X, Sun X, Deng Y, Liu J, Lei B, Sun Z. Simultaneous electrochemical determination of guanosine and adenosine with graphene–ZrO2 nanocomposite modified carbon ionic liquid electrode. Biosens Bioelectron 2013; 44:146-51. [DOI: 10.1016/j.bios.2013.01.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 01/04/2013] [Accepted: 01/15/2013] [Indexed: 10/27/2022]
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Heimfarth L, Loureiro SO, Dutra MF, Petenuzzo L, de Lima BO, Fernandes CG, da Rocha JBT, Pessoa-Pureur R. Disrupted cytoskeletal homeostasis, astrogliosis and apoptotic cell death in the cerebellum of preweaning rats injected with diphenyl ditelluride. Neurotoxicology 2013. [DOI: 10.1016/j.neuro.2012.10.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Thauerer B, Zur Nedden S, Baier-Bitterlich G. Purine nucleosides: endogenous neuroprotectants in hypoxic brain. J Neurochem 2012; 121:329-42. [PMID: 22335456 PMCID: PMC3499684 DOI: 10.1111/j.1471-4159.2012.07692.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Even a short blockade of oxygen flow in brain may lead to the inhibition of oxidative phosphorylation and depletion of cellular ATP, which results in profound deficiencies in cellular function. Following ischemia, dying, injured, and hypoxic cells release soluble purine-nucleotide and -nucleoside pools. Growing evidence suggests that purine nucleosides might act as trophic factors in the CNS and PNS. In addition to equilibrative nucleoside transporters (ENTs) regulating purine nucleoside concentrations intra- and extracellularly, specific extracellular receptor subtypes for these compounds are expressed on neurons, glia, and endothelial cells, mediating stunningly diverse effects. Such effects range from induction of cell differentiation, apoptosis, mitogenesis, and morphogenetic changes, to stimulation of synthesis and/or release of cytokines and neurotrophic factors under both physiological and pathological conditions. Multiple signaling pathways regulate the critical balance between cell death and survival in hypoxia-ischemia. A convergent pathway for the regulation of multiple modalities involved in O₂ sensing is the mitogen activated protein kinase (p42/44 MAPK) or (ERK1/2 extracellular signal-regulated kinases) pathway terminating in a variety of transcription factors, for example, hypoxia-inducible factor 1α. In this review, the coherence of purine nucleoside-related pathways and MAPK activation in the endogenous neuroprotective regulation of the nervous system's development and neuroplasticity under hypoxic stress will be discussed.
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Affiliation(s)
- Bettina Thauerer
- Division of Neurobiochemistry, Biocenter Department, Medical University of Innsbruck, Innsbruck, Austria
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Mekhail M, Almazan G, Tabrizian M. Oligodendrocyte-protection and remyelination post-spinal cord injuries: a review. Prog Neurobiol 2012; 96:322-39. [PMID: 22307058 DOI: 10.1016/j.pneurobio.2012.01.008] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2011] [Revised: 01/09/2012] [Accepted: 01/19/2012] [Indexed: 12/28/2022]
Abstract
In the past four decades, the main focus of investigators in the field of spinal cord regeneration has been to devise therapeutic measures that enhance neural regeneration. More recently, emphasis has been placed on enhancing remyelination and providing oligodendrocyte-protection after a spinal cord injury (SCI). Demyelination post-SCI is part of the cascading secondary injury that takes place immediately after the primary insult; therefore, therapeutic measures are needed to reduce oligodendrocyte death and/or enhance remyelination during the acute stage, preserving neurological functions that would be lost otherwise. In this review a thorough investigation of the oligodendrocyte-protective and remyelinative molecular therapies available to date is provided. The advent of new biomaterials shown to promote remyelination post-SCI is discussed mainly in the context of a combinatorial approach where the biomaterial also provides drug delivery capabilities. The aim of these molecular and biomaterial-based therapies is twofold: (1) oligodendrocyte-protective therapy, which involves protecting already existing oligodendrocytes from undergoing apoptosis/necrosis; and (2) inductive remyelination, which involves harnessing the remyelinative capabilities of endogenous oligodendrocyte precursor cells (OPCs) at the lesion site by providing a suitable environment for their migration, survival, proliferation and differentiation. From the evidence reported in the literature, we conclude that the use of a combinatorial approach including biomaterials and molecular therapies would provide advantages such as: (1) sustained release of the therapeutic molecule, (2) local delivery at the lesion site, and (3) an environment at the site of injury that promotes OPC migration, differentiation and remyelination.
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Affiliation(s)
- Mina Mekhail
- Department of Biomedical Engineering, McGill University, Montreal, Quebec, Canada.
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da Cunha MJ, da Cunha AA, Ferreira AGK, Machado FR, Schmitz F, Lima DD, Delwing D, Mussulini BHM, Wofchuk S, Netto CA, Wyse ATS. Physical exercise reverses glutamate uptake and oxidative stress effects of chronic homocysteine administration in the rat. Int J Dev Neurosci 2012; 30:69-74. [PMID: 22244886 DOI: 10.1016/j.ijdevneu.2012.01.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 01/01/2012] [Indexed: 02/04/2023] Open
Abstract
The influence of physical exercise on the effects elicited by homocysteine on glutamate uptake and some parameters of oxidative stress, namely thiobarbituric acid-reactive substances, 2',7'-dichlorofluorescein (H(2)DCF) oxidation, as well as enzymatic antioxidant activities, superoxide dismutase, catalase and glutathione peroxidase in rat cerebral cortex were investigated. Wistar rats received subcutaneous administration of homocysteine or saline (control) from the 6th to 29th day of life. The physical exercise was performed from the 30th to 60th day of life; 12 h after the last exercise session animals were sacrificed and the cerebral cortex was dissected out. It is shown that homocysteine reduces glutamate uptake increases thiobarbituric acid-reactive substances and disrupts enzymatic antioxidant defenses in cerebral cortex. Physical activity reversed the homocysteine effects on glutamate uptake and on antioxidant enzymes activities; although the increase in thiobarbituric acid-reactive substances was only partially reversed by exercise. These findings allow us to suggest that physical exercise may have a protective role against homocysteine-induced oxidative imbalance and brain damage to the glutamatergic system.
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Affiliation(s)
- Maira J da Cunha
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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Dalla Corte CL, Bastos LL, Dobrachinski F, Rocha JB, Soares FA. The combination of organoselenium compounds and guanosine prevents glutamate-induced oxidative stress in different regions of rat brains. Brain Res 2012; 1430:101-11. [DOI: 10.1016/j.brainres.2011.10.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 10/07/2011] [Accepted: 10/28/2011] [Indexed: 10/15/2022]
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Effects of chronic guanosine treatment on hippocampal damage and cognitive impairment of rats submitted to chronic cerebral hypoperfusion. Neurol Sci 2011; 33:985-97. [PMID: 22167652 DOI: 10.1007/s10072-011-0872-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 11/23/2011] [Indexed: 01/22/2023]
Abstract
Chronic cerebral hypoperfusion contributes to a cognitive decline related to brain disorders. Its experimental model in rats is a permanent bilateral common carotid artery occlusion (2VO). Overstimulation of the glutamatergic system excitotoxicity due to brain energetic disturbance in 2VO animals seems to play a pivotal role as a mechanism of cerebral damage. The nucleoside guanosine (GUO) exerts extracellular effects including antagonism of glutamatergic activity. Accordingly, our group demonstrated several neuroprotective effects of GUO against glutamatergic excitotoxicity. Therefore, in this study, we evaluated a chronic GUO treatment effects in rats submitted to 2VO. We evaluated the animals performance in the Morris water maze and hippocampal damage by neurons and astrocytes immunohistochemistry. In addition, we investigated the cerebrospinal fluid (CSF) brain derived neurotrophic factor (BDNF) and serum S100B levels. Additionally, the purine CSF and plasma levels were determined. GUO treatment did not prevent the cognitive impairment promoted by 2VO. However, none of the 2VO animals treated with GUO showed differences in the hippocampal regions compared to control, while 20% of 2VO rats not treated with GUO presented loss of pyramidal neurons and increased glial labeling cells in CA1 hippocampal region. In addition, we did not observe differences in CSF BDNF nor serum S100B levels among the groups. Of note, both the 2VO surgery and GUO treatment changed the purine CSF and plasma profile. In conclusion, GUO treatment did not prevent the cognitive impairment observed in 2VO animals, but our data suggest that GUO could be neuroprotective against hippocampal damage induced by 2VO.
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41
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Ferreira AGK, da Cunha AA, Scherer EB, Machado FR, da Cunha MJ, Braga A, Mussulini BH, Moreira JD, Wofchuk S, Souza DO, Wyse ATS. Evidence that hyperprolinemia alters glutamatergic homeostasis in rat brain: neuroprotector effect of guanosine. Neurochem Res 2011; 37:205-13. [PMID: 21935728 DOI: 10.1007/s11064-011-0604-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 09/10/2011] [Indexed: 10/17/2022]
Abstract
This study investigated the effects of acute and chronic hyperprolinemia on glutamate uptake, as well as some mechanisms underlying the proline effects on glutamatergic system in rat cerebral cortex. The protective role of guanosine on effects mediated by proline was also evaluated. Results showed that acute and chronic hyperprolinemia reduced glutamate uptake, Na(+), K(+)-ATPase activity, ATP levels and increased lipoperoxidation. GLAST and GLT-1 immunocontent were increased in acute, but not in chronic hyperprolinemic rats. Our data suggest that the effects of proline on glutamate uptake may be mediated by lipid peroxidation and disruption of Na(+), K(+)-ATPase activity, but not by decreasing in glutamate transporters. This probably induces excitotoxicity and subsequent energy deficit. Guanosine was effective to prevent most of the effects promoted by proline, reinforcing its modulator role in counteracting the glutamate toxicity. However, further studies are needed to assess the modulatory effects of guanosine on experimental hyperprolinemia.
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Affiliation(s)
- Andréa G K Ferreira
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, CEP 90035-003, Brazil
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42
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Ganzella M, Moreira JD, Almeida RF, Böhmer AE, Saute JAM, Holmseth S, Souza DO. Effects of 3 weeks GMP oral administration on glutamatergic parameters in mice neocortex. Purinergic Signal 2011; 8:49-58. [PMID: 21881961 DOI: 10.1007/s11302-011-9258-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 08/11/2011] [Indexed: 10/17/2022] Open
Abstract
Overstimulation of the glutamatergic system (excitotoxicity) is involved in various acute and chronic brain diseases. Several studies support the hypothesis that guanosine-5'-monophosphate (GMP) can modulate glutamatergic neurotransmission. The aim of this study was to evaluate the effects of chronically administered GMP on brain cortical glutamatergic parameters in mice. Additionally, we investigated the neuroprotective potential of the GMP treatment submitting cortical brain slices to oxygen and glucose deprivation (OGD). Moreover, measurements of the cerebrospinal fluid (CSF) purine levels were performed after the treatment. Mice received an oral administration of saline or GMP during 3 weeks. GMP significantly decreases the cortical brain glutamate binding and uptake. Accordingly, GMP reduced the immunocontent of the glutamate receptors subunits, NR2A/B and GluR1 (NMDA and AMPA receptors, respectively) and glutamate transporters EAAC1 and GLT1. GMP treatment significantly reduced the immunocontent of PSD-95 while did not affect the content of Snap 25, GLAST and GFAP. Moreover, GMP treatment increased the resistance of neocortex to OGD insult. The chronic GMP administration increased the CSF levels of GMP and its metabolites. Altogether, these findings suggest a potential modulatory role of GMP on neocortex glutamatergic system by promoting functional and plastic changes associated to more resistance of mice neocortex against an in vitro excitotoxicity event.
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Affiliation(s)
- Marcelo Ganzella
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, 90035-003, Porto Alegre, RS, Brazil,
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Molz S, Dal-Cim T, Budni J, Martín-de-Saavedra MD, Egea J, Romero A, del Barrio L, Rodrigues ALS, López MG, Tasca CI. Neuroprotective effect of guanosine against glutamate-induced cell death in rat hippocampal slices is mediated by the phosphatidylinositol-3 kinase/Akt/ glycogen synthase kinase 3β pathway activation and inducible nitric oxide synthase inhibition. J Neurosci Res 2011; 89:1400-8. [PMID: 21671255 DOI: 10.1002/jnr.22681] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 03/25/2011] [Accepted: 04/01/2011] [Indexed: 01/13/2023]
Abstract
Excitotoxicity and cell death induced by glutamate are involved in many neurodegenerative disorders. We have previously demonstrated that excitotoxicity induced by millimolar concentrations of glutamate in hippocampal slices involves apoptotic features and glutamate-induced glutamate release. Guanosine, an endogenous guanine nucleoside, prevents excitotoxicity by its ability to modulate glutamate transport. In this study, we have evaluated the neuroprotective effect of guanosine against glutamate-induced toxicity in hippocampal slices and the mechanism involved in such an effect. We have found that guanosine (100 μM) was neuroprotective against 1 mM glutamate-induced cell death through the inhibition of glutamate release induced by glutamate. Guanosine also induced the phosphorylation and, thus, activation of protein kinase B (PKB/Akt), a downstream target of phosphatidylinositol-3 kinase (PI3K), as well as phosphorylation of glycogen synthase kinase 3β, which has been reported to be inactivated by Akt after phosphorylation at Ser9. Glutamate treated hippocampal slices showed increased inducible nitric oxide synthase (iNOS) expression that was prevented by guanosine. Slices preincubated with SNAP (an NO donor), inhibited the protective effect of guanosine. LY294002 (30 μM), a PI3K inhibitor, attenuated guanosine-induced neuroprotection, guanosine prevention of glutamate release, and guanosine-induced GSK3β(Ser9) phosphorylation but not guanosine reduction of glutamate-induced iNOS expression. Taken together, the results of this study show that guanosine protects hippocampal slices by a mechanism that involves the PI3K/Akt/GSK3β(Ser9) pathway and prevention of glutamate-induced glutamate release. Furthermore, guanosine also reduces glutamate-induced iNOS by a PI3K/Akt-independent mechanism.
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Affiliation(s)
- Simone Molz
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Trindade, Florianópolis, SC, Brasil. molz.s @hotmail.com
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Cui L, Yin H, Ai S, Li L. Electrocatalysis Oxidation of GMP Based on Layered Double Hydroxide Functionalized with Anionic Surfactant and Room Temperature Ionic Liquid Modified Glassy Carbon Electrode. CHINESE J CHEM 2011. [DOI: 10.1002/cjoc.201190165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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45
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Guanosine is neuroprotective against oxygen/glucose deprivation in hippocampal slices via large conductance Ca²+-activated K+ channels, phosphatidilinositol-3 kinase/protein kinase B pathway activation and glutamate uptake. Neuroscience 2011; 183:212-20. [PMID: 21435378 DOI: 10.1016/j.neuroscience.2011.03.022] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 03/04/2011] [Accepted: 03/09/2011] [Indexed: 12/20/2022]
Abstract
Guanine derivatives (GD) have been implicated in many relevant brain extracellular roles, such as modulation of glutamate transmission and neuronal protection against excitotoxic damage. GD are spontaneously released to the extracellular space from cultured astrocytes and during oxygen/glucose deprivation (OGD). The aim of this study has been to evaluate the potassium channels and phosphatidilinositol-3 kinase (PI3K) pathway involvement in the mechanisms related to the neuroprotective role of guanosine in rat hippocampal slices subjected to OGD. The addition of guanosine (100 μM) to hippocampal slices subjected to 15 min of OGD and followed by 2 h of re-oxygenation is neuroprotective. The presence of K+ channel blockers, glibenclamide (20 μM) or apamin (300 nM), revealed that neuroprotective effect of guanosine was not dependent on ATP-sensitive K+ channels or small conductance Ca²+-activated K+ channels. The presence of charybdotoxin (100 nM), a large conductance Ca²+-activated K+ channel (BK) blocker, inhibited the neuroprotective effect of guanosine. Hippocampal slices subjected to OGD and re-oxygenation showed a significant reduction of glutamate uptake. Addition of guanosine in the re-oxygenation period has blocked the reduction of glutamate uptake. This guanosine effect was inhibited when hippocampal slices were pre-incubated with charybdotoxin or wortmanin (a PI3K inhibitor, 1 μM) in the re-oxygenation period. Guanosine promoted an increase in Akt protein phosphorylation. However, the presence of charybdotoxin blocked such effect. In conclusion, the neuroprotective effect of guanosine involves augmentation of glutamate uptake, which is modulated by BK channels and the activation of PI3K pathway. Moreover, neuroprotection caused by guanosine depends on the increased expression of phospho-Akt protein.
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Machado FR, Ferreira AGK, da Cunha AA, Tagliari B, Mussulini BHM, Wofchuk S, Wyse ATS. Homocysteine alters glutamate uptake and Na+,K+-ATPase activity and oxidative status in rats hippocampus: protection by vitamin C. Metab Brain Dis 2011; 26:61-7. [PMID: 21287399 DOI: 10.1007/s11011-011-9232-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Accepted: 01/12/2011] [Indexed: 11/29/2022]
Abstract
In the present study we investigate the effect of homocysteine on glutamate uptake, Na+,K+-ATPase, enzymatic antioxidant defenses, as well as reactive species levels in hippocampus of rats. The influence of vitamin C, a classic antioxidant, on the effects elicited by homocysteine was also tested. Results showed that chronic hyperhomocysteinemia decreased glutamate uptake and the activities of Na+,K+-ATPase, catalase and superoxide dismutase in hippocampus of rats. Reactive species levels were increased by chronic homocysteine administration. Concomitant administration of vitamin C significantly prevented these alterations caused by homocysteine. According to our results, it seems possible to suggest that the reduction in glutamate uptake and Na+,K+-ATPase activity may be mediated by oxidative stress, since vitamin C prevented these effects. We suggest that the administration of antioxidants should be considered as an adjuvant therapy to specific diet in homocystinuria.
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Affiliation(s)
- Fernanda R Machado
- Laboratório de Neuroproteção e Doença Metabólica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003 Porto Alegre, RS, Brazil
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47
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Chronic stress and lithium treatments alter hippocampal glutamate uptake and release in the rat and potentiate necrotic cellular death after oxygen and glucose deprivation. Neurochem Res 2011; 36:793-800. [PMID: 21253855 DOI: 10.1007/s11064-011-0404-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2011] [Indexed: 01/02/2023]
Abstract
This study was undertaken to evaluate the effects of chronic variate stress and lithium treatment on glutamatergic activity and neuronal vulnerability of rat hippocampus. Male Wistar rats were simultaneously treated with lithium and submitted to a chronic variate stress protocol during 40 days, and afterwards the hippocampal glutamatergic uptake and release, measured in slices and synaptosomes, were evaluated. We observed an increased synaptosomal [(3)H]glutamate uptake and an increase in [(3)H]glutamate stimulated release in hippocampus of lithium-treated rats. Chronic stress increased basal [(3)H]glutamate release by synaptosomes, and decreased [(3)H]glutamate uptake in hippocampal slices. When evaluating cellular vulnerability, both stress and lithium increased cellular death after oxygen and glucose deprivation (OGD). We suggest that the manipulation of glutamatergic activity induced by stress may be in part responsible for the neuroendangerment observed after stress exposure, and that, in spite of the described neuroprotective effects of lithium, it increased the neuronal vulnerability after OGD.
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Gubert P, Ávila DS, Bridi JC, Saurin S, Lugokenski TH, Villarinho JG, Fachinetto R, Pereira ME, Ferreira J, da Rocha JBT, Soares FAA. Low concentrations of methamidophos do not alter AChE activity but modulate neurotransmitters uptake in hippocampus and striatum in vitro. Life Sci 2011; 88:89-95. [DOI: 10.1016/j.lfs.2010.10.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 09/25/2010] [Accepted: 10/26/2010] [Indexed: 11/24/2022]
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Oses JP, Batassini C, Pochmann D, Böhmer AE, Vuaden FC, Silvestrin RB, Oliveira A, Bonan CD, Bogo MR, Souza DO, Portela LVC, Sarkis JJDF, Mello e Souza T. The hydrolysis of striatal adenine- and guanine-based purines in a 6-hydroxydopamine rat model of Parkinson's disease. Neurochem Res 2010; 36:215-22. [PMID: 21046237 DOI: 10.1007/s11064-010-0305-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2010] [Indexed: 01/08/2023]
Abstract
Parkinson's disease (PD) is characterized by a progressive neurodegeneration in the substantia nigra and a striatal dopamine decrease. Striatal extracellular adenosine and ATP modulate the dopaminergic neurotransmission whereas guanosine has a protective role in the brain. Therefore, the regulation of their levels by enzymatic activity may be relevant to the clinical feature of PD. Here it was evaluated the extracellular nucleotide hydrolysis from striatal slices 4 weeks after a unilateral infusion with 6-OHDA into the medial forebrain bundle. This infusion increased ADP, AMP, and GTP hydrolysis by 15, 25, and 41%, respectively, and decreased GDP hydrolysis by 60%. There was no change in NTPDases1, 2, 3, 5, 6, and 5'-nucleotidase transcription. Dopamine depletion changes nucleotide hydrolysis and, therefore, alters the regulation of striatal nucleotide levels. These changes observed in 6-OHDA-lesioned animals may contribute to the symptoms observed in the model and provide evidence to indicate that extracellular purine hydrolysis is a key factor in understanding PD, giving hints for new therapies.
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Affiliation(s)
- Jean Pierre Oses
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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Can guanine-based purines be considered modulators of intestinal motility in rodents? Eur J Pharmacol 2010; 650:350-5. [PMID: 20940015 DOI: 10.1016/j.ejphar.2010.09.062] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 09/01/2010] [Accepted: 09/20/2010] [Indexed: 01/11/2023]
Abstract
Adenine-based purines play a pivotal role in the control of gastrointestinal motility in rodents. Recently, guanine-based purines have been also shown to exert extracellular effects in the central nervous system raising the possibility of the existence of distinct receptors for guanine-based purines. Thus, it seems likely to speculate that also guanine-based purines may play a role in the modulation of the intestinal contractility. Spontaneous and neurally-evoked mechanical activity was recorded in vitro as changes in isometric tension in circular muscle strips from mouse distal colon. Guanosine up to 3mM or guanine up to 1mM failed to affect the spontaneous mechanical activity, but reduced the amplitude of the electrical field stimulation (EFS)-induced cholinergic contractions, without affecting the early nitrergic relaxation. Both compounds failed to affect the direct contractile responses evoked by carbachol. No desensitization of the response was observed. Guanine-based purine effects were not altered by theophylline, P1 purinoceptor antagonist, by PPADS or suramin, P2 purinoceptor antagonists, by ODQ, guanilyl cyclase inhibitor, or by DDA, adenylyl cyclase inhibitor. Nucleoside uptake inhibitors, dipyridamole or 6-[(4-Nitrobenzyl)thio]-9-β-D-ribofuranosylpurine (NBTI), antagonized the inhibitory effects induced by guanosine without interfering with guanine. On the contrary, adenine, a competitive inhibitor of nucleobase uptake, antagonized guanine-induced effects. In conclusion, our data indicate that guanosine and guanine are able to modulate negatively the excitatory cholinergic neurotransmission in the circular muscle layer of mouse colon. Guanine-based purines appear to interfere with prejunctional acethylcoline release. Their effects are dependent by their cellular uptake, and independent by adenine-based purine receptors.
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