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Wang M, Chen S, Zhong C, Liu L, Wang G, Huang X, Yang X, Yang H, Li L. The influence of simulated weightlessness on the composition and function of gut microbiota and bile acid metabolism products. LIFE SCIENCES IN SPACE RESEARCH 2024; 41:18-28. [PMID: 38670645 DOI: 10.1016/j.lssr.2024.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 11/15/2023] [Accepted: 01/08/2024] [Indexed: 04/28/2024]
Abstract
The aim of this study was to investigate the effects of simulated weightlessness on gut microbiota, bile acid metabolism, and inflammatory cytokines compared to the control group. The study compared the changes in gut microbiota at the phylum and genus levels in the feces of control and weightlessness rats after 1 and 8 weeks using fecal 16S rRNA sequencing. In the weightlessness group, there was an increase in the proportion of anaerobic bacteria and biofilm-forming bacteria, and a decrease in the proportion of aerobic and Gram-negative bacteria. Further investigations explored the impact of weightlessness on bile acid metabolism products. The levels of glycine ursodeoxycholic acid, glycine chenodeoxycholic acid, glycine deoxycholic acid and glycine cholic acid levels were lower in rats undergoing weightlessness for 1 week compared to the control group.Moreover, the study examined the relationship between gut microbiota and bile acid metabolism products.It was observed that, unlike the control group, there were significant positive correlations between Planctomycetes, Proteobacteria, Synergistetes, and GUDCA levels in rats after 1 week of weightlessness. Finally, ELISA results indicated significant differences in the levels of MDA, GSH, NLRP3, and SIgA inflammatory cytokines between rats undergoing weightlessness for 1 week and the control group rats. Our research confirmed that the simulated weightlessness environment significantly affects the gut microbiota and bile acid metabolism in rats, potentially leading to changes in inflammatory cytokines and causing intestinal tissue inflammation. Further exploring the relationship between gut microbiota and bile acid metabolism under weightless conditions will be crucial for understanding the functional changes in the intestines caused by weightlessness.
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Affiliation(s)
- Min Wang
- Department of Gastroenterology, PLA Strategic Support Force Characteristic Medical Center, No. 9 Anxiang North Lane, Chaoyang District, Beijing 100101, China
| | - Sheng Chen
- Department of Gastroenterology, PLA Strategic Support Force Characteristic Medical Center, No. 9 Anxiang North Lane, Chaoyang District, Beijing 100101, China
| | - Changqing Zhong
- Department of Gastroenterology, PLA Strategic Support Force Characteristic Medical Center, No. 9 Anxiang North Lane, Chaoyang District, Beijing 100101, China
| | - Lei Liu
- Department of Gastroenterology, PLA Strategic Support Force Characteristic Medical Center, No. 9 Anxiang North Lane, Chaoyang District, Beijing 100101, China
| | - Guodong Wang
- Department of Gastroenterology, PLA Strategic Support Force Characteristic Medical Center, No. 9 Anxiang North Lane, Chaoyang District, Beijing 100101, China
| | - Xin Huang
- Department of Gastroenterology, PLA Strategic Support Force Characteristic Medical Center, No. 9 Anxiang North Lane, Chaoyang District, Beijing 100101, China
| | - Xiaoman Yang
- Department of Pathology, PLA Strategic Support Force Characteristic Medical Center, No. 9 Anxiang North Lane, Chaoyang District, Beijing 100101, China
| | - Heming Yang
- Department of General Surgery, PLA Strategic Support Force Characteristic Medical Center, No. 9 Anxiang North Lane, Chaoyang District, Beijing 100101, China.
| | - Lianyong Li
- Department of Gastroenterology, PLA Strategic Support Force Characteristic Medical Center, No. 9 Anxiang North Lane, Chaoyang District, Beijing 100101, China.
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Han X, Qu L, Yu M, Ye L, Shi L, Ye G, Yang J, Wang Y, Fan H, Wang Y, Tan Y, Wang C, Li Q, Lei W, Chen J, Liu Z, Shen Z, Li Y, Hu S. Thiamine-modified metabolic reprogramming of human pluripotent stem cell-derived cardiomyocyte under space microgravity. Signal Transduct Target Ther 2024; 9:86. [PMID: 38584163 PMCID: PMC10999445 DOI: 10.1038/s41392-024-01791-7] [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: 06/08/2023] [Revised: 02/08/2024] [Accepted: 03/12/2024] [Indexed: 04/09/2024] Open
Abstract
During spaceflight, the cardiovascular system undergoes remarkable adaptation to microgravity and faces the risk of cardiac remodeling. Therefore, the effects and mechanisms of microgravity on cardiac morphology, physiology, metabolism, and cellular biology need to be further investigated. Since China started constructing the China Space Station (CSS) in 2021, we have taken advantage of the Shenzhou-13 capsule to send human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) to the Tianhe core module of the CSS. In this study, hPSC-CMs subjected to space microgravity showed decreased beating rate and abnormal intracellular calcium cycling. Metabolomic and transcriptomic analyses revealed a battery of metabolic remodeling of hPSC-CMs in spaceflight, especially thiamine metabolism. The microgravity condition blocked the thiamine intake in hPSC-CMs. The decline of thiamine utilization under microgravity or by its antagonistic analog amprolium affected the process of the tricarboxylic acid cycle. It decreased ATP production, which led to cytoskeletal remodeling and calcium homeostasis imbalance in hPSC-CMs. More importantly, in vitro and in vivo studies suggest that thiamine supplementation could reverse the adaptive changes induced by simulated microgravity. This study represents the first astrobiological study on the China Space Station and lays a solid foundation for further aerospace biomedical research. These data indicate that intervention of thiamine-modified metabolic reprogramming in human cardiomyocytes during spaceflight might be a feasible countermeasure against microgravity.
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Affiliation(s)
- Xinglong Han
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, State Key Laboratory of Radiation Medicine and Protection, Suzhou Medical College, Soochow University, Suzhou, China
| | - Lina Qu
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Miao Yu
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, State Key Laboratory of Radiation Medicine and Protection, Suzhou Medical College, Soochow University, Suzhou, China
| | - Lingqun Ye
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, State Key Laboratory of Radiation Medicine and Protection, Suzhou Medical College, Soochow University, Suzhou, China
| | - Liujia Shi
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Guangfu Ye
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Jingsi Yang
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, State Key Laboratory of Radiation Medicine and Protection, Suzhou Medical College, Soochow University, Suzhou, China
| | - Yaning Wang
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, State Key Laboratory of Radiation Medicine and Protection, Suzhou Medical College, Soochow University, Suzhou, China
| | - Hao Fan
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, State Key Laboratory of Radiation Medicine and Protection, Suzhou Medical College, Soochow University, Suzhou, China
| | - Yong Wang
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, State Key Laboratory of Radiation Medicine and Protection, Suzhou Medical College, Soochow University, Suzhou, China
| | - Yingjun Tan
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Chunyan Wang
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Qi Li
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Wei Lei
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, State Key Laboratory of Radiation Medicine and Protection, Suzhou Medical College, Soochow University, Suzhou, China
| | - Jianghai Chen
- Department of Hand Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhaoxia Liu
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China
| | - Zhenya Shen
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, State Key Laboratory of Radiation Medicine and Protection, Suzhou Medical College, Soochow University, Suzhou, China.
| | - Yinghui Li
- State Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing, China.
| | - Shijun Hu
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, State Key Laboratory of Radiation Medicine and Protection, Suzhou Medical College, Soochow University, Suzhou, China.
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Liu T, Melkus G, Ramsay T, Sheikh A, Laneuville O, Trudel G. Bone marrow adiposity modulation after long duration spaceflight in astronauts. Nat Commun 2023; 14:4799. [PMID: 37558686 PMCID: PMC10412640 DOI: 10.1038/s41467-023-40572-8] [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: 04/03/2023] [Accepted: 07/31/2023] [Indexed: 08/11/2023] Open
Abstract
Space travel requires metabolic adaptations from multiple systems. While vital to bone and blood production, human bone marrow adipose (BMA) tissue modulation in space is unknown. Here we show significant downregulation of the lumbar vertebrae BMA in 14 astronauts, 41 days after landing from six months' missions on the International Space Station. Spectral analyses indicated depletion of marrow adipose reserves. We then demonstrate enhanced erythropoiesis temporally related to low BMA. Next, we demonstrated systemic and then, local lumbar vertebrae bone anabolism temporally related to low BMA. These support the hypothesis that BMA is a preferential local energy source supplying the hypermetabolic bone marrow postflight, leading to its downregulation. A late postflight upregulation abolished the lower BMA of female astronauts and BMA modulation amplitude was higher in younger astronauts. The study design in the extreme environment of space can limit these conclusions. BMA modulation in astronauts can help explain observations on Earth.
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Affiliation(s)
- Tammy Liu
- Bone and Joint Research Laboratory, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8M2, Canada
| | - Gerd Melkus
- Department of Radiology, Radiation Oncology and Medical Physics, University of Ottawa, Ottawa, ON, K1H 8M2, Canada
| | - Tim Ramsay
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, K1H 8M2, Canada
| | - Adnan Sheikh
- Department of Radiology, Radiation Oncology and Medical Physics, University of Ottawa, Ottawa, ON, K1H 8M2, Canada
| | - Odette Laneuville
- Department of Biology, Faculty of Science, University of Ottawa, Ottawa, ON, Canada
| | - Guy Trudel
- Bone and Joint Research Laboratory, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8M2, Canada.
- Department of Medicine, Division of Physical Medicine and Rehabilitation, The Ottawa Hospital, Ottawa, ON, K1H 8M2, Canada.
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M2, Canada.
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Bonanni R, Cariati I, Marini M, Tarantino U, Tancredi V. Microgravity and Musculoskeletal Health: What Strategies Should Be Used for a Great Challenge? Life (Basel) 2023; 13:1423. [PMID: 37511798 PMCID: PMC10381503 DOI: 10.3390/life13071423] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/14/2023] [Accepted: 06/20/2023] [Indexed: 07/30/2023] Open
Abstract
Space colonization represents the most insidious challenge for mankind, as numerous obstacles affect the success of space missions. Specifically, the absence of gravitational forces leads to systemic physiological alterations, with particular emphasis on the musculoskeletal system. Indeed, astronauts exposed to spaceflight are known to report a significant impairment of bone microarchitecture and muscle mass, conditions clinically defined as osteoporosis and sarcopenia. In this context, space medicine assumes a crucial position, as the development of strategies to prevent and/or counteract weightlessness-induced alterations appears to be necessary. Furthermore, the opportunity to study the biological effects induced by weightlessness could provide valuable information regarding adaptations to spaceflight and suggest potential treatments that can preserve musculoskeletal health under microgravity conditions. Noteworthy, improving knowledge about the latest scientific findings in this field of research is crucial, as is thoroughly investigating the mechanisms underlying biological adaptations to microgravity and searching for innovative solutions to counter spaceflight-induced damage. Therefore, this narrative study review, performed using the MEDLINE and Google Scholar databases, aims to summarize the most recent evidence regarding the effects of real and simulated microgravity on the musculoskeletal system and to discuss the effectiveness of the main defence strategies used in both real and experimental settings.
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Affiliation(s)
- Roberto Bonanni
- Department of Clinical Sciences and Translational Medicine, "Tor Vergata" University of Rome, Via Montpellier 1, 00133 Rome, Italy
| | - Ida Cariati
- Department of Systems Medicine, "Tor Vergata" University of Rome, Via Montpellier 1, 00133 Rome, Italy
| | - Mario Marini
- Department of Systems Medicine, "Tor Vergata" University of Rome, Via Montpellier 1, 00133 Rome, Italy
| | - Umberto Tarantino
- Department of Clinical Sciences and Translational Medicine, "Tor Vergata" University of Rome, Via Montpellier 1, 00133 Rome, Italy
- Department of Orthopaedics and Traumatology, "Policlinico Tor Vergata" Foundation, Viale Oxford 81, 00133 Rome, Italy
- Centre of Space Bio-Medicine, "Tor Vergata" University of Rome, Via Montpellier 1, 00133 Rome, Italy
| | - Virginia Tancredi
- Department of Systems Medicine, "Tor Vergata" University of Rome, Via Montpellier 1, 00133 Rome, Italy
- Centre of Space Bio-Medicine, "Tor Vergata" University of Rome, Via Montpellier 1, 00133 Rome, Italy
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Patel OV, Partridge C, Plaut K. Space Environment Impacts Homeostasis: Exposure to Spaceflight Alters Mammary Gland Transportome Genes. Biomolecules 2023; 13:biom13050872. [PMID: 37238741 DOI: 10.3390/biom13050872] [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: 03/09/2023] [Revised: 04/22/2023] [Accepted: 05/16/2023] [Indexed: 05/28/2023] Open
Abstract
Membrane transporters and ion channels that play an indispensable role in metabolite trafficking have evolved to operate in Earth's gravity. Dysregulation of the transportome expression profile at normogravity not only affects homeostasis along with drug uptake and distribution but also plays a key role in the pathogenesis of diverse localized to systemic diseases including cancer. The profound physiological and biochemical perturbations experienced by astronauts during space expeditions are well-documented. However, there is a paucity of information on the effect of the space environment on the transportome profile at an organ level. Thus, the goal of this study was to analyze the effect of spaceflight on ion channels and membrane substrate transporter genes in the periparturient rat mammary gland. Comparative gene expression analysis revealed an upregulation (p < 0.01) of amino acid, Ca2+, K+, Na+, Zn2+, Cl-, PO43-, glucose, citrate, pyruvate, succinate, cholesterol, and water transporter genes in rats exposed to spaceflight. Genes associated with the trafficking of proton-coupled amino acids, Mg2+, Fe2+, voltage-gated K+-Na+, cation-coupled chloride, as well as Na+/Ca2+ and ATP-Mg/Pi exchangers were suppressed (p < 0.01) in these spaceflight-exposed rats. These findings suggest that an altered transportome profile contributes to the metabolic modulations observed in the rats exposed to the space environment.
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Affiliation(s)
- Osman V Patel
- Cell and Molecular Biology Department, Grand Valley State University, Allendale, MI 49401, USA
| | - Charlyn Partridge
- Annis Water Resources Institute, Grand Valley State University, Muskegon, MI 49441, USA
| | - Karen Plaut
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47906, USA
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Le H, Rai V, Agrawal DK. Cholesterol: An Important Determinant of Muscle Atrophy in Astronauts. JOURNAL OF BIOTECHNOLOGY AND BIOMEDICINE 2023; 6:67-79. [PMID: 37006714 PMCID: PMC10062007 DOI: 10.26502/jbb.2642-91280072] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Since cholesterol is not routinely measured in astronauts before and after their return from space, there is no data on the role of blood cholesterol level in muscle atrophy and microgravity. Since the first moon landing, aerospace medicine became outdated and has not pushed boundaries like its rocket engineering counterpart. Since the 2019 astronaut twin study, there has yet to be another scientific breakthrough for aerospace medicine. Microgravity-induced muscle atrophy is the most known consequence of spaceflight. Yet, so far, there is no therapeutic solution to prevent it or any real efforts in understanding it on a cellular or molecular level. The most obvious reason to this unprecedented level of research is due to the small cohort of astronauts. With the establishment of private space industries and exponential recruitment of astronauts, there is more reason to push forward spaceflight-related health guidelines and ensure the safety of the brave humans who risk their lives for the progression of mankind. Spaceflight is considered the most challenging job and the failure to prevent injury or harm should be considered reckless negligence by the institutions that actively prevented sophistication of aerospace medicine. In this critical review, role of cholesterol is analyzed across the NASA-established parameters of microgravity-induced muscle atrophy with a focus on potential therapeutic targets for research.
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Affiliation(s)
- Hoangvi Le
- Department of Translational Research, Western University of Health Sciences, Pomona, California 91766, USA
| | - Vikrant Rai
- Department of Translational Research, Western University of Health Sciences, Pomona, California 91766, USA
| | - Devendra K Agrawal
- Department of Translational Research, Western University of Health Sciences, Pomona, California 91766, USA
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Chaloulakou S, Poulia KA, Karayiannis D. Physiological Alterations in Relation to Space Flight: The Role of Nutrition. Nutrients 2022; 14:nu14224896. [PMID: 36432580 PMCID: PMC9699067 DOI: 10.3390/nu14224896] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/11/2022] [Accepted: 11/14/2022] [Indexed: 11/22/2022] Open
Abstract
Astronauts exhibit several pathophysiological changes due to a variety of stressors related to the space environment, including microgravity, space radiation, isolation, and confinement. Space motion sickness, bone and muscle mass loss, cardiovascular deconditioning and neuro-ocular syndrome are some of the spaceflight-induced effects on human health. Optimal nutrition is of the utmost importance, and-in combination with other measures, such as physical activity and pharmacological treatment-has a key role in mitigating many of the above conditions, including bone and muscle mass loss. Since the beginning of human space exploration, space food has not fully covered astronauts' needs. They often suffer from menu fatigue and present unintentional weight loss, which leads to further alterations. The purpose of this review was to explore the role of nutrition in relation to the pathophysiological effects of spaceflight on the human body.
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Affiliation(s)
- Stavroula Chaloulakou
- Department of Clinical Nutrition, “Evangelismos” General Hospital of Athens, 10676 Athens, Greece
| | - Kalliopi Anna Poulia
- Laboratory of Dietetics and Quality of Life, Department of Food Science & Human Nutrition, School of Food and Nutritional Sciences, Agricultural University of Athens, 11855 Athens, Greece
| | - Dimitrios Karayiannis
- Department of Clinical Nutrition, “Evangelismos” General Hospital of Athens, 10676 Athens, Greece
- Correspondence: ; Tel.: +30-213-2045035
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Locatelli L, Castiglioni S, Maier JAM. From Cultured Vascular Cells to Vessels: The Cellular and Molecular Basis of Vascular Dysfunction in Space. Front Bioeng Biotechnol 2022; 10:862059. [PMID: 35480977 PMCID: PMC9036997 DOI: 10.3389/fbioe.2022.862059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/18/2022] [Indexed: 11/23/2022] Open
Abstract
Life evolved on this planet under the pull of gravity, shielded from radiation by the magnetosphere and shaped by circadian rhythms due to Earth’s rotation on its axis. Once living beings leave such a protective environment, adaptive responses are activated to grant survival. In view of long manned mission out of Earth’s orbit, it is relevant to understand how humans adapt to space and if the responses activated might reveal detrimental in the long run. Here we review present knowledge about the effects on the vessels of various extraterrestrial factors on humans as well as in vivo and in vitro experimental models. It emerges that the vasculature activates complex adaptive responses finalized to supply oxygen and nutrients to all the tissues and to remove metabolic waste and carbon dioxide. Most studies point to oxidative stress and mitochondrial dysfunction as mediators of vascular alterations in space. Unraveling the cellular and molecular mechanisms involved in these adaptive processes might offer hints to design proper and personalized countermeasures to predict a safe future in space.
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Affiliation(s)
- Laura Locatelli
- Department of Biomedical and Clinical Sciences L. Sacco, Università di Milano, Milano, Italy
| | - Sara Castiglioni
- Department of Biomedical and Clinical Sciences L. Sacco, Università di Milano, Milano, Italy
| | - Jeanette A M Maier
- Department of Biomedical and Clinical Sciences L. Sacco, Università di Milano, Milano, Italy.,Interdisciplinary Centre for Nanostructured Materials and Interfaces (CIMaINa), Università di Milano, Milan, Italy
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Cardiovascular, Lymphatic, and Ocular Health in Space. Life (Basel) 2022; 12:life12020268. [PMID: 35207555 PMCID: PMC8875500 DOI: 10.3390/life12020268] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/22/2022] [Accepted: 02/08/2022] [Indexed: 12/01/2022] Open
Abstract
Life on Earth has evolved continuously under Earth’s 1 G force and the protection of the magnetosphere. Thus, astronauts exhibit maladaptive physiological responses during space travel. Exposure to harmful cosmic radiation and weightlessness are unique conditions to the deep-space environment responsible for several spaceflight-associated risks: visual impairment, immune dysfunction, and cancer due to cosmic radiation in astronauts. The evidence thus reviewed indicates that microgravity and cosmic radiation have deleterious effects on the cardiovascular, lymphatic, and vision systems of astronauts on long-duration space missions. The mechanisms responsible for the decline in these systems are potentially due to cytoskeletal filament rearrangement, endothelial dysfunction, and muscular atrophy. These factors may alter fluid hemodynamics within cardiovascular and lymphatic vasculatures such that greater fluid filtration causes facial and intracranial edema. Thus, microgravity induces cephalad fluid shifts contributing to spaceflight-associated neuro-ocular syndrome (SANS). Moreover, visual impairment via retinal ischemia and altered nitric oxide production may alter endothelial function. Based on rodent studies, cosmic radiation may exacerbate the effects of microgravity as observed in impaired endothelium and altered immunity. Relevant findings help understand the extent of these risks associated with spaceflight and suggest relevant countermeasures to protect astronaut health during deep-space missions.
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