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Tonev D, Momchilova A. Oxidative Stress and the Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) Pathway in Multiple Sclerosis: Focus on Certain Exogenous and Endogenous Nrf2 Activators and Therapeutic Plasma Exchange Modulation. Int J Mol Sci 2023; 24:17223. [PMID: 38139050 PMCID: PMC10743556 DOI: 10.3390/ijms242417223] [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] [Received: 10/26/2023] [Revised: 11/18/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023] Open
Abstract
The pathogenesis of multiple sclerosis (MS) suggests that, in genetically susceptible subjects, T lymphocytes undergo activation in the peripheral compartment, pass through the BBB, and cause damage in the CNS. They produce pro-inflammatory cytokines; induce cytotoxic activities in microglia and astrocytes with the accumulation of reactive oxygen species, reactive nitrogen species, and other highly reactive radicals; activate B cells and macrophages and stimulate the complement system. Inflammation and neurodegeneration are involved from the very beginning of the disease. They can both be affected by oxidative stress (OS) with different emphases depending on the time course of MS. Thus, OS initiates and supports inflammatory processes in the active phase, while in the chronic phase it supports neurodegenerative processes. A still unresolved issue in overcoming OS-induced lesions in MS is the insufficient endogenous activation of the Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) pathway, which under normal conditions plays an essential role in mitochondria protection, OS, neuroinflammation, and degeneration. Thus, the search for approaches aiming to elevate endogenous Nrf2 activation is capable of protecting the brain against oxidative damage. However, exogenous Nrf2 activators themselves are not without drawbacks, necessitating the search for new non-pharmacological therapeutic approaches to modulate OS. The purpose of the present review is to provide some relevant preclinical and clinical examples, focusing on certain exogenous and endogenous Nrf2 activators and the modulation of therapeutic plasma exchange (TPE). The increased plasma levels of nerve growth factor (NGF) in response to TPE treatment of MS patients suggest their antioxidant potential for endogenous Nrf2 enhancement via NGF/TrkA/PI3K/Akt and NGF/p75NTR/ceramide-PKCζ/CK2 signaling pathways.
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Affiliation(s)
- Dimitar Tonev
- Department of Anesthesiology and Intensive Care, University Hospital “Tzaritza Yoanna—ISUL”, Medical University of Sofia, 1527 Sofia, Bulgaria
| | - Albena Momchilova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Science, 1113 Sofia, Bulgaria;
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Seo SY, Kim YJ, Kim J, Nam MH, Park KY. Phytosphingosine induces systemic acquired resistance through activation of sphingosine kinase. PLANT DIRECT 2021; 5:e351. [PMID: 34622122 PMCID: PMC8483070 DOI: 10.1002/pld3.351] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 10/13/2020] [Accepted: 09/08/2021] [Indexed: 05/11/2023]
Abstract
Phytosphingosine (PHS) is a naturally occurring bioactive sphingolipid molecule. Intermediates such as sphingolipid long-chain bases (LCBs) in sphingolipid biosynthesis have been shown to have important roles as signaling molecules. PHS treatment caused rapid cell damage and upregulated the generation of reactive oxygen species (ROS) and ethylene in tobacco plants. These events were followed by the induction of sphingosine kinase (SphK) in a biphasic manner, which metabolized PHS to phytosphingosine-1-phosphate (PHS-1-P). On the other hand, a PHS treatment with a virulent pathogen, Phytophthora parasitica var. nicotianae (Ppn), alleviated the pathogen-induced cell damage and reduced the growth of Ppn. A Ppn infection increased the PHS and PHS-1-P levels significantly in the upper part of the leaves at the infection site at the later stage. In addition, Ppn increased the transcription levels of serine palmitoyltransferase (LCB1 and LCB2) for sphingolipid biosynthesis at the later stage, which was enhanced further by PHS. Moreover, the PHS treatment increased the transcription and activity of SphK, which was accompanied by prominent increases in the transcription levels of ROS-detoxifying enzymes and PR proteins in the later phase of the pathogen infection. Overall, the PHS-induced resistant effects were prominent during the necrotic stage of this hemibiotrophic infection, indicating that it is more beneficial for inhibiting the pathogenicity on necrotic cell death. Phosphorylated LCBs reduced the pathogen-induced cell damage significantly in this stage. These results suggest that the selective channeling of sphingolipids into phosphorylated forms has a pro-survival effect on plant immunity.
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Affiliation(s)
- So Yeon Seo
- Department of Biology Sunchon National University Suncheon Republic of Korea
| | - Yu Jung Kim
- Department of Biology Sunchon National University Suncheon Republic of Korea
| | - Jinwoo Kim
- Seoul Center Korea Basic Science Institute (KBSI) Seoul Republic of Korea
| | - Myung Hee Nam
- Seoul Center Korea Basic Science Institute (KBSI) Seoul Republic of Korea
| | - Ky Young Park
- Department of Biology Sunchon National University Suncheon Republic of Korea
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Hao Y, Guo M, Feng Y, Dong Q, Cui M. Lysophospholipids and Their G-Coupled Protein Signaling in Alzheimer's Disease: From Physiological Performance to Pathological Impairment. Front Mol Neurosci 2020; 13:58. [PMID: 32351364 PMCID: PMC7174595 DOI: 10.3389/fnmol.2020.00058] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 03/24/2020] [Indexed: 12/21/2022] Open
Abstract
Lysophospholipids (LPLs) are bioactive signaling lipids that are generated from phospholipase-mediated hydrolyzation of membrane phospholipids (PLs) and sphingolipids (SLs). Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are two of the best-characterized LPLs which mediate a variety of cellular physiological responses via specific G-protein coupled receptor (GPCR) mediated signaling pathways. Considerable evidence now demonstrates the crucial role of LPA and S1P in neurodegenerative diseases, especially in Alzheimer’s disease (AD). Dysfunction of LPA and S1P metabolism can lead to aberrant accumulation of amyloid-β (Aβ) peptides, the formation of neurofibrillary tangles (NFTs), neuroinflammation and ultimately neuronal death. Summarizing LPA and S1P signaling profile may aid in profound health and pathological processes. In the current review, we will introduce the metabolism as well as the physiological roles of LPA and S1P in maintaining the normal functions of the nervous system. Given these pivotal functions, we will further discuss the role of dysregulation of LPA and S1P in promoting AD pathogenesis.
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Affiliation(s)
- Yining Hao
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Min Guo
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Yiwei Feng
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Qiang Dong
- Department of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Mei Cui
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
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Torretta E, Barbacini P, Al-Daghri NM, Gelfi C. Sphingolipids in Obesity and Correlated Co-Morbidities: The Contribution of Gender, Age and Environment. Int J Mol Sci 2019; 20:ijms20235901. [PMID: 31771303 PMCID: PMC6929069 DOI: 10.3390/ijms20235901] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/20/2019] [Accepted: 11/22/2019] [Indexed: 02/07/2023] Open
Abstract
This paper reviews our present knowledge on the contribution of ceramide (Cer), sphingomyelin (SM), dihydroceramide (DhCer) and sphingosine-1-phosphate (S1P) in obesity and related co-morbidities. Specifically, in this paper, we address the role of acyl chain composition in bodily fluids for monitoring obesity in males and females, in aging persons and in situations of environmental hypoxia adaptation. After a brief introduction on sphingolipid synthesis and compartmentalization, the node of detection methods has been critically revised as the node of the use of animal models. The latter do not recapitulate the human condition, making it difficult to compare levels of sphingolipids found in animal tissues and human bodily fluids, and thus, to find definitive conclusions. In human subjects, the search for putative biomarkers has to be performed on easily accessible material, such as serum. The serum “sphingolipidome” profile indicates that attention should be focused on specific acyl chains associated with obesity, per se, since total Cer and SM levels coupled with dyslipidemia and vitamin D deficiency can be confounding factors. Furthermore, exposure to hypoxia indicates a relationship between dyslipidemia, obesity, oxygen level and aerobic/anaerobic metabolism, thus, opening new research avenues in the role of sphingolipids.
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Affiliation(s)
- Enrica Torretta
- Department of Biomedical Sciences for Health, University of Milan, Luigi Mangiagalli 31, 20133 Milan, Italy; (E.T.); (P.B.)
| | - Pietro Barbacini
- Department of Biomedical Sciences for Health, University of Milan, Luigi Mangiagalli 31, 20133 Milan, Italy; (E.T.); (P.B.)
- Ph.D. school in Molecular and Translational Medicine, University of Milan, 20142 Milan, Italy
| | - Nasser M. Al-Daghri
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department,College of Science, King Saud University, Riyadh 11451, Saudi Arabia;
| | - Cecilia Gelfi
- Department of Biomedical Sciences for Health, University of Milan, Luigi Mangiagalli 31, 20133 Milan, Italy; (E.T.); (P.B.)
- I.R.C.C.S Orthopedic Institute Galeazzi, R. Galeazzi 4, 20161 Milan, Italy
- Correspondence: ; Tel.: +39-025-033-0475
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Park KM, Wang JW, Yoo YM, Choi MJ, Hwang KC, Jeung EB, Jeong YW, Hwang WS. Sphingosine-1-phosphate (S1P) analog phytosphingosine-1-phosphate (P1P) improves the in vitro maturation efficiency of porcine oocytes via regulation of oxidative stress and apoptosis. Mol Reprod Dev 2019; 86:1705-1719. [PMID: 31490595 DOI: 10.1002/mrd.23264] [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: 04/08/2019] [Accepted: 08/03/2019] [Indexed: 12/11/2022]
Abstract
Phytosphingosine-1-phosphate (P1P) is a signaling sphingolipid that regulates various physiological activities. However, little is known about the effect of P1P in the context of reproduction. Thus, we aimed to investigate the influence of P1P on oocyte maturation during porcine in vitro maturation (IVM). Here, we report the expression of S1PR1-3 among P1P receptors (S1PR1-4) in cumulus cells and oocytes. When P1P was administered at concentrations of 10, 50, 100, and 1,000 nM during IVM, the metaphase II rate was significantly increased in the 1,000 nM (1 μM) P1P treatment group. Maturation rate improvement by P1P supplementation was observed only in the presence of epidermal growth factor (EGF). Oocytes under the influence of P1P showed decreased intracellular reactive oxygen species levels but no significant differences in glutathione levels. In our molecular studies, P1P treatment upregulated gene expression involved in cumulus expansion (Has2 and EGF), antioxidant enzymes (SOD3 and Cat), and developmental competence (Oct4) while activating extracellular signal-regulated kinase1/2 and Akt signaling. P1P treatment also influenced oocyte survival by shifting the ratio of Bcl-2 to Bax while inactivating JNK signaling. We further demonstrated that oocytes matured with P1P displayed significantly higher developmental competence (cleavage and blastocyst [BL] formation rate) and greater BL quality (total cell number and the ratio of apoptotic cells) when activated via parthenogenetic activation (PA) and in vitro fertilization. Despite the low levels of endogenous P1P found in animals, exogenous P1P influenced animal reproduction, as shown by increased porcine oocyte maturation as well as preimplantation embryo development. This study and its findings are potentially relevant for both human and animal-assisted reproduction.
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Affiliation(s)
- Kyu-Mi Park
- Sooam Biotech Research Foundation, Guro-gu, Seoul, Republic of Korea
| | - Jae Woong Wang
- Sooam Biotech Research Foundation, Guro-gu, Seoul, Republic of Korea
| | - Yeong-Min Yoo
- Laboratory of Biochemistry and Molecular Biology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | | | - Kyu Chan Hwang
- Sooam Biotech Research Foundation, Guro-gu, Seoul, Republic of Korea
| | - Eui-Bae Jeung
- Laboratory of Biochemistry and Molecular Biology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | - Yeon Woo Jeong
- Sooam Biotech Research Foundation, Guro-gu, Seoul, Republic of Korea
| | - Woo Suk Hwang
- Sooam Biotech Research Foundation, Guro-gu, Seoul, Republic of Korea
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Rahar B, Chawla S, Tulswani R, Saxena S. Acute Hypobaric Hypoxia-Mediated Biochemical/Metabolic Shuffling and Differential Modulation of S1PR-SphK in Cardiac and Skeletal Muscles. High Alt Med Biol 2019; 20:78-88. [PMID: 30892968 DOI: 10.1089/ham.2018.0046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
AIM High altitude exposure alters biochemical, metabolic, and physiological features of heart and skeletal muscles, and hence has pathological consequences in these tissues. Central to these hypoxia-associated biochemical/metabolic shuffling are energy deficit accumulation of free radicals and ensuing oxidative damage in the tissue. Recent preclinical/clinical studies indicate sphingosine-1-phosphate (S1P) axis, comprising S1P G protein coupled receptors (S1PR1-5) and its synthesizing enzyme-sphingosine kinase (SphK) to have key regulatory roles in homeostatic cardiac and skeletal muscle biology. In view of this, the aim of the present study was to chart the initiation and progression of biochemical/metabolic shuffling and assess the coincident differential modulation of S1PR(1-5) expression and total SphK activity in cardiac and skeletal muscles from rats exposed to progressive hypobaric hypoxia (HH; 21,000 feet for 12, 24, and 48 hours). RESULTS HH-associated responses were evident as raised damage markers in plasma, oxidative stress, decreased total tissue protein, imbalance of intermediate metabolites, and aerobic/anaerobic enzyme activities in cardiac and skeletal muscles (gastrocnemius and soleus) culminating as energy deficit. CONCLUSION Cardiac and gastrocnemius muscles were more susceptible to hypoxic environment than soleus muscle. These differential responses were directly and indirectly coincident with temporal expression of S1PR(1-5) and SphK activity.
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Affiliation(s)
- Babita Rahar
- 1 Experimental Biology Division, Defense Institute of Physiology and Allied Sciences, Defense Research and Development Organization, Delhi, India
| | - Sonam Chawla
- 1 Experimental Biology Division, Defense Institute of Physiology and Allied Sciences, Defense Research and Development Organization, Delhi, India
| | - Rajkumar Tulswani
- 2 PACT Division, Defense Institute of Physiology and Allied Sciences, Defense Research and Development Organization, Delhi, India
| | - Shweta Saxena
- 3 Medicinal and Aromatic Plant Division, Defense Institute of High Altitude Research (DIHAR), Defense Research and Development Organization, Jammu and Kashmir, India
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Rahar B, Chawla S, Pandey S, Bhatt AN, Saxena S. Sphingosine-1-phosphate pretreatment amends hypoxia-induced metabolic dysfunction and impairment of myogenic potential in differentiating C2C12 myoblasts by stimulating viability, calcium homeostasis and energy generation. J Physiol Sci 2018; 68:137-151. [PMID: 28070865 PMCID: PMC10717551 DOI: 10.1007/s12576-016-0518-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 12/26/2016] [Indexed: 12/19/2022]
Abstract
Sphingosine-1-phosphate (S1P) has a role in transpiration in patho-physiological signaling in skeletal muscles. The present study evaluated the pre-conditioning efficacy of S1P in facilitating differentiation of C2C12 myoblasts under a normoxic/hypoxic cell culture environment. Under normoxia, exogenous S1P significantly promoted C2C12 differentiation as evident from morphometric descriptors and differentiation markers of the mature myotubes, but it could facilitate only partial recovery from hypoxia-induced compromised differentiation. Pretreatment of S1P optimized the myokine secretion, intracellular calcium release and energy generation by boosting the aerobic/anaerobic metabolism and mitochondrial mass. In the hypoxia-exposed cells, there was derangement of the S1PR1-3 expression patterns, while the same could be largely restored with S1P pretreatment. This is being proposed as a plausible underlying mechanism for the observed pro-myogenic efficacy of exogenous S1P preconditioning. The present findings are an invaluable addition to the existing knowledge on the pro-myogenic potential of S1P and may prove beneficial in the field of hypoxia-related myo-pathologies.
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Affiliation(s)
- Babita Rahar
- Experimental Biology Division, Defence Institute of Physiology and Allied Sciences (DIPAS), Defence Research and Development Organization (DRDO), Lucknow Road, Timarpur, Delhi, 110054, India
| | - Sonam Chawla
- Experimental Biology Division, Defence Institute of Physiology and Allied Sciences (DIPAS), Defence Research and Development Organization (DRDO), Lucknow Road, Timarpur, Delhi, 110054, India
| | - Sanjay Pandey
- Division of Metabolic and Cell Signaling Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), Defence Research and Development Organization (DRDO), Brig. S.K. Mazumdar Road, Delhi, 110054, India
| | - Anant Narayan Bhatt
- Division of Metabolic and Cell Signaling Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), Defence Research and Development Organization (DRDO), Brig. S.K. Mazumdar Road, Delhi, 110054, India
| | - Shweta Saxena
- Medicinal and Aromatic Plant Division, Defence Institute of High Altitude Research (DIHAR), Defence Research and Development Organization (DRDO), Ministry of Defence, Leh-Ladakh, 194101, Jammu and Kashmir, India.
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Chawla S, Rahar B, Saxena S. S1P prophylaxis mitigates acute hypobaric hypoxia-induced molecular, biochemical, and metabolic disturbances: A preclinical report. IUBMB Life 2016; 68:365-75. [PMID: 26959531 DOI: 10.1002/iub.1489] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 02/13/2016] [Indexed: 12/17/2022]
Abstract
Sphingosine-1-phosphate (S1P) is emerging to have hypoxic preconditioning potential in various preclinical studies. The study aims to evaluate the preclinical preconditioning efficacy of exogenously administered S1P against acute hypobaric hypoxia (HH)-induced pathological disturbances. Male Sprague Dawley rats (200 ± 20 g) were preconditioned with 1, 10, and 100 μg/kg body weight (b.w.) S1P (i.v.) for three consecutive days. On the third day, S1P preconditioned animals, along with hypoxia control animals, were exposed to HH equivalent to 7,620 m (280 mm Hg) for 6 h. Postexposure status of cardiac energy production, circulatory vasoactive mediators, pulmonary and cerebral oxidative damage, and inflammation were assessed. HH exposure led to cardiac energy deficit indicated by low ATP levels and pronounced AMPK activation levels, raised circulatory levels of brain natriuretic peptide and endothelin-1 with respect to total nitrate (NOx), redox imbalance, inflammation, and alterations in NOx levels in the pulmonary and cerebral tissues. These pathological precursors have been routinely reported to be coincident with high-altitude diseases. Preconditioning with S1P, especially 1 µg/kg b.w. dose, was seen to reverse the manifestation of these pathological disturbances. The protective efficacy could be attributed, at least in part, to enhanced activity of cardioprotective protein kinase C and activation of small GTPase Rac1, which led to further induction of hypoxia-adaptive molecular mediators: hypoxia-inducible factor (HIF)-1α and Hsp70. This is a first such report, to the best of our knowledge, elucidating the mechanism of exogenous S1P-mediated HIF-1α/Hsp70 induction. Conclusively, systemic preconditioning with 1 μg/kg b.w. S1P in rats protects against acute HH-induced pathological disturbances. © 2016 IUBMB Life 68(5):365-375, 2016.
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Affiliation(s)
- Sonam Chawla
- Experimental Biology Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization, Timarpur, New Delhi, India
| | - Babita Rahar
- Experimental Biology Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization, Timarpur, New Delhi, India
| | - Shweta Saxena
- Experimental Biology Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization, Timarpur, New Delhi, India
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Ghasemi R, Dargahi L, Ahmadiani A. Integrated sphingosine-1 phosphate signaling in the central nervous system: From physiological equilibrium to pathological damage. Pharmacol Res 2016; 104:156-64. [DOI: 10.1016/j.phrs.2015.11.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 11/14/2015] [Accepted: 11/15/2015] [Indexed: 01/09/2023]
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Differential Modulation of S1PR(1–5) and Specific Activities of SphK and nSMase in Pulmonary and Cerebral Tissues of Rats Exposed to Hypobaric Hypoxia. Lipids 2014; 50:39-48. [DOI: 10.1007/s11745-014-3967-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 10/22/2014] [Indexed: 01/18/2023]
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Exogenous sphingosine-1-phosphate boosts acclimatization in rats exposed to acute hypobaric hypoxia: assessment of haematological and metabolic effects. PLoS One 2014; 9:e98025. [PMID: 24887065 PMCID: PMC4041657 DOI: 10.1371/journal.pone.0098025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 04/27/2014] [Indexed: 12/31/2022] Open
Abstract
Background The physiological challenges posed by hypobaric hypoxia warrant exploration of pharmacological entities to improve acclimatization to hypoxia. The present study investigates the preclinical efficacy of sphingosine-1-phosphate (S1P) to improve acclimatization to simulated hypobaric hypoxia. Experimental Approach Efficacy of intravenously administered S1P in improving haematological and metabolic acclimatization was evaluated in rats exposed to simulated acute hypobaric hypoxia (7620m for 6 hours) following S1P pre-treatment for three days. Major Findings Altitude exposure of the control rats caused systemic hypoxia, hypocapnia (plausible sign of hyperventilation) and respiratory alkalosis due to suboptimal renal compensation indicated by an overt alkaline pH of the mixed venous blood. This was associated with pronounced energy deficit in the hepatic tissue along with systemic oxidative stress and inflammation. S1P pre-treatment improved blood oxygen-carrying-capacity by increasing haemoglobin, haematocrit, and RBC count, probably as an outcome of hypoxia inducible factor-1α mediated erythropoiesis and renal S1P receptor 1 mediated haemoconcentation. The improved partial pressure of oxygen in the blood could further restore aerobic respiration and increase ATP content in the hepatic tissue of S1P treated animals. S1P could also protect the animals from hypoxia mediated oxidative stress and inflammation. Conclusion The study findings highlight S1P’s merits as a preconditioning agent for improving acclimatization to acute hypobaric hypoxia exposure. The results may have long term clinical application for improving physiological acclimatization of subjects venturing into high altitude for occupational or recreational purposes.
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