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Abstract
Cross-talk between peripheral tissues is essential to ensure the coordination of nutrient intake with disposition during the feeding period, thereby preventing metabolic disease. This mini-review considers the interactions between the key peripheral tissues that constitute the metabolic clock, each of which is considered in a separate mini-review in this collation of articles published in Endocrinology in 2020 and 2021, by Martchenko et al (Circadian rhythms and the gastrointestinal tract: relationship to metabolism and gut hormones); Alvarez et al (The microbiome as a circadian coordinator of metabolism); Seshadri and Doucette (Circadian regulation of the pancreatic beta cell); McCommis et al (The importance of keeping time in the liver); Oosterman et al (The circadian clock, shift work, and tissue-specific insulin resistance); and Heyde et al (Contributions of white and brown adipose tissues to the circadian regulation of energy metabolism). The use of positive- and negative-feedback signals, both hormonal and metabolic, between these tissues ensures that peripheral metabolic pathways are synchronized with the timing of food intake, thus optimizing nutrient disposition and preventing metabolic disease. Collectively, these articles highlight the critical role played by the circadian clock in maintaining metabolic homeostasis.
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Affiliation(s)
- Patricia L Brubaker
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8Canada
- Department of Medicine, University of Toronto, Toronto, Ontario M5S 1A8Canada
- Correspondence: P. L. Brubaker, PhD, Departments of Physiology and Medicine, University of Toronto, Medical Sciences Bldg, Rm 3366, 1 King’s College Cir, Toronto, ON M5S 1A8, Canada.
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Tang H, Rising HH, Majji M, Brown RD. Long-Term Space Nutrition: A Scoping Review. Nutrients 2021; 14:nu14010194. [PMID: 35011072 PMCID: PMC8747021 DOI: 10.3390/nu14010194] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/23/2021] [Accepted: 12/28/2021] [Indexed: 01/30/2023] Open
Abstract
This scoping review aimed to identify current evidence and gaps in the field of long-term space nutrition. Specifically, the review targeted critical nutritional needs during long-term manned missions in outer space in addition to the essential components of a sustainable space nutrition system for meeting these needs. The search phrase "space food and the survival of astronauts in long-term missions" was used to collect the initial 5432 articles from seven Chinese and seven English databases. From these articles, two independent reviewers screened titles and abstracts to identify 218 articles for full-text reviews based on three themes and 18 keyword combinations as eligibility criteria. The results suggest that it is possible to address short-term adverse environmental factors and nutritional deficiencies by adopting effective dietary measures, selecting the right types of foods and supplements, and engaging in specific sustainable food production and eating practices. However, to support self-sufficiency during long-term space exploration, the most optimal and sustainable space nutrition systems are likely to be supported primarily by fresh food production, natural unprocessed foods as diets, nutrient recycling of food scraps and cultivation systems, and the establishment of closed-loop biospheres or landscape-based space habitats as long-term life support systems.
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Affiliation(s)
- Hong Tang
- College of Landscape and Tourism, Gansu Agricultural University, Lanzhou 730070, China;
| | - Hope Hui Rising
- Department of Landscape Architecture and Urban Planning, Texas A&M University, College Station, TX 77843, USA;
- Correspondence:
| | - Manoranjan Majji
- Department of Aerospace Engineering, Texas A&M University, College Station, TX 77843, USA;
| | - Robert D. Brown
- Department of Landscape Architecture and Urban Planning, Texas A&M University, College Station, TX 77843, USA;
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Benazzi S, Gorini S, Feraco A, Caprio M. Ritmi circadiani e variabili metaboliche. L'ENDOCRINOLOGO 2021. [PMCID: PMC8569496 DOI: 10.1007/s40619-021-00983-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
I ritmi circadiani sono influenzati da numerose variabili correlate allo stile di vita, soprattutto in relazione ai ritmi imposti dalla società moderna, e vengono profondamente alterati da diverse condizioni patologiche. La fisiologia circadiana è organizzata in modo complesso e integrato; molti dei fattori che sincronizzano il sistema sono a loro volta influenzati e regolati da diversi assi ormonali. Parallelamente, i disturbi del ritmo circadiano derivano da input non ottimali dei fattori sincronizzanti o da condizioni patologiche, e le conseguenze determinano un impatto significativo in diverse condizioni, quali l’obesità e i disturbi del sonno. Durante l’attuale emergenza COVID-19 sono stati registrati crescenti tassi di alterazioni del sonno, complici la preoccupazione diffusa, un comportamento alimentare alterato e la difficoltà per molti, durante il lockdown, nel mantenere ritmi di vita regolari (Barrea et al. in J Transl Med 18:1–11, 2020). Le misure di intervento che si sono mostrate più promettenti contro la desincronizzazione circadiana sono quelle che agiscono sullo stile di vita, basate sul recupero di un corretto ritmo del sonno, la corretta esposizione alla luce solare, l’idonea distribuzione dei pasti e del timing alimentare e lo svolgimento di un’adeguata attività fisica.
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Álvarez-Vásquez JL, Bravo-Guapisaca MI, Gavidia-Pazmiño JF, Intriago-Morales RV. Adipokines in dental pulp: physiological, pathological, and potential therapeutic roles. J Oral Biosci 2021; 64:59-70. [PMID: 34808362 DOI: 10.1016/j.job.2021.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 11/12/2021] [Accepted: 11/15/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND Hundreds of adipokines have been identified, and their extensive range of endocrine functions-regulating distant organs such as oral tissues-and local autocrine/paracrine roles have been studied. In dentistry, however, adipokines are poorly known proteins in the dental pulp; few of them have been studied despite their large number. This study reviews recent advances in the investigation of dental-pulp adipokines, with an emphasis on their roles in inflammatory processes and their potential therapeutic applications. HIGHLIGHTS The most recently identified adipokines in dental pulp include leptin, adiponectin, resistin, ghrelin, oncostatin, chemerin, and visfatin. They have numerous physiological and pathological functions in the pulp tissue: they are closely related to pulp inflammatory mechanisms and actively participate in cell differentiation, mineralization, angiogenesis, and immune-system modulation. CONCLUSION Adipokines have potential clinical applications in regenerative endodontics and as biomarkers or targets for the pharmacological management of inflammatory and degenerative processes in dental pulp. A promising direction for the development of new therapies may be the use of agonists/antagonists to modulate the expression of the most studied adipokines.
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Man AWC, Xia N, Li H. Circadian Rhythm in Adipose Tissue: Novel Antioxidant Target for Metabolic and Cardiovascular Diseases. Antioxidants (Basel) 2020; 9:E968. [PMID: 33050331 PMCID: PMC7601443 DOI: 10.3390/antiox9100968] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 09/29/2020] [Accepted: 10/03/2020] [Indexed: 12/11/2022] Open
Abstract
Obesity is a major risk factor for most metabolic and cardiovascular disorders. Adipose tissue is an important endocrine organ that modulates metabolic and cardiovascular health by secreting signaling molecules. Oxidative stress is a common mechanism associated with metabolic and cardiovascular complications including obesity, type 2 diabetes, and hypertension. Oxidative stress can cause adipose tissue dysfunction. Accumulating data from both humans and experimental animal models suggest that adipose tissue function and oxidative stress have an innate connection with the intrinsic biological clock. Circadian clock orchestrates biological processes in adjusting to daily environmental changes according to internal or external cues. Recent studies have identified the genes and molecular pathways exhibiting circadian expression patterns in adipose tissue. Disruption of the circadian rhythmicity has been suggested to augment oxidative stress and aberrate adipose tissue function and metabolism. Therefore, circadian machinery in the adipose tissue may be a novel therapeutic target for the prevention and treatment of metabolic and cardiovascular diseases. In this review, we summarize recent findings on circadian rhythm and oxidative stress in adipose tissue, dissect the key components that play a role in regulating the clock rhythm, oxidative stress and adipose tissue function, and discuss the potential use of antioxidant treatment on metabolic and cardiovascular diseases by targeting the adipose clock.
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Affiliation(s)
| | | | - Huige Li
- Department of Pharmacology, Johannes Gutenberg University Medical Center, Langenbeckstr, 1, 55131 Mainz, Germany; (A.W.C.M.); (N.X.)
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Hironao KY, Mitsuhashi Y, Huang S, Oike H, Ashida H, Yamashita Y. Cacao polyphenols regulate the circadian clock gene expression and through glucagon-like peptide-1 secretion. J Clin Biochem Nutr 2020; 67:53-60. [PMID: 32801469 PMCID: PMC7417799 DOI: 10.3164/jcbn.20-38] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 03/24/2020] [Indexed: 12/26/2022] Open
Abstract
Energy metabolism and circadian rhythms are closely related together, i.e., the timing of nutrient intake affects metabolism under the regulation of circadian rhythms. Previously, we have reported that cacao liquor procyanidin (CLPr) promotes energy metabolism, resulting in preventing obesity and hyperglycemia. However, it is not unclear whether CLPr regulates clock gene expression. In this study, we investigated whether the administration timing of CLPr affected clock gene expression and found that CLPr regulated the circadian clock gene expression through the glucagon-like peptide-1 (GLP-1) signaling pathway. CLPr administration at Zeitgeber time 3 increased the expression level of Per family and Dbp in the liver. At the same administration timing, CLPr increased GLP-1 and insulin concentration in the plasma and phosphorylation of AMPK in the liver. It was noteworthy that an antagonist for GLP-1 receptor Exendin (9-39) canceled CLPr-increased expression of Per family and Dbp and phosphorylation of AMPK in the liver, in addition to insulin secretion. These results strongly suggest that CLPr-induced GLP-1 regulates the changes in clock gene expression in the liver through increased insulin. Thus, CLPr is a possible functional food material for prevention and/or amelioration of metabolic disorders through preventing circadian disruption through GLP-1 and AMPK pathways.
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Affiliation(s)
- Ken-Yu Hironao
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Yuji Mitsuhashi
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Shujiao Huang
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Hideaki Oike
- Food Research Institute, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-8642, Japan
| | - Hitoshi Ashida
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Yoko Yamashita
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
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Daskalakis G, Bellos I, Nikolakea M, Pergialiotis V, Papapanagiotou A, Loutradis D. The role of serum adipokine levels in preeclampsia: A systematic review. Metabolism 2020; 106:154172. [PMID: 32027908 DOI: 10.1016/j.metabol.2020.154172] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 01/27/2020] [Accepted: 02/02/2020] [Indexed: 01/14/2023]
Abstract
BACKGROUND Preeclampsia represents a major pregnancy complication, associated with high rates of perinatal morbidity. The aim of this systematic review is to accumulate current literature evidence in order to examine the pattern of serum adipokine levels among preeclamptic women and asses their potential efficacy in the prediction of the disease. METHODS Medline, Scopus, CENTRAL, Clinicaltrials.gov and Google Scholar databases were systematically searched from inception. All observational studies reporting serum adipokine values among preeclamptic and healthy pregnant women were held eligible. RESULTS A total of 163 studies were included, comprising 23,482 women. Leptin was evaluated in 91 studies and its values were found to be significantly elevated in preeclamptic women during all pregnancy trimester, independently of disease onset and severity. Preeclampsia was also associated with increased serum fatty acid binding protein-4 and chemerin levels, when measured both during the 1st and 3rd trimester. Data concerning the rest adipokines were either conflicting or limited to reach firm conclusions. Quality of evidence was evaluated to be high for leptin, moderate for serum fatty acid binding protein-4 and chemerin and low for the other adipokines. CONCLUSIONS The existing evidence suggests that preeclampsia is linked to increased levels of leptin, chemerin and fatty acid binding protein-4 in all pregnancy trimesters and forms of the disease. Inconsistent data currently exists concerning the role of the other adipokines. Large-scale prospective studies should longitudinally evaluate the serum concentration of novel adipokines and define the optimal threshold and timing of measurement to be widely applied in clinical practice.
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Affiliation(s)
- Georgios Daskalakis
- First Department of Obstetrics and Gynecology, Alexandra Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Ioannis Bellos
- Laboratory of Experimental Surgery and Surgical Research N.S. Christeas, Athens University Medical School, National and Kapodistrian University of Athens, Greece.
| | - Melina Nikolakea
- Laboratory of Experimental Surgery and Surgical Research N.S. Christeas, Athens University Medical School, National and Kapodistrian University of Athens, Greece
| | - Vasilios Pergialiotis
- Laboratory of Experimental Surgery and Surgical Research N.S. Christeas, Athens University Medical School, National and Kapodistrian University of Athens, Greece
| | - Angeliki Papapanagiotou
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Dimitrios Loutradis
- First Department of Obstetrics and Gynecology, Alexandra Hospital, National and Kapodistrian University of Athens, Athens, Greece
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Pickel L, Sung HK. Feeding Rhythms and the Circadian Regulation of Metabolism. Front Nutr 2020; 7:39. [PMID: 32363197 PMCID: PMC7182033 DOI: 10.3389/fnut.2020.00039] [Citation(s) in RCA: 110] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/20/2020] [Indexed: 12/16/2022] Open
Abstract
The molecular circadian clock regulates metabolic processes within the cell, and the alignment of these clocks between tissues is essential for the maintenance of metabolic homeostasis. The possibility of misalignment arises from the differential responsiveness of tissues to the environmental cues that synchronize the clock (zeitgebers). Although light is the dominant environmental cue for the master clock of the suprachiasmatic nucleus, many other tissues are sensitive to feeding and fasting. When rhythms of feeding behavior are altered, for example by shift work or the constant availability of highly palatable foods, strong feedback is sent to the peripheral molecular clocks. Varying degrees of phase shift can cause the systemic misalignment of metabolic processes. Moreover, when there is a misalignment between the endogenous rhythms in physiology and environmental inputs, such as feeding during the inactive phase, the body's ability to maintain homeostasis is impaired. The loss of phase coordination between the organism and environment, as well as internal misalignment between tissues, can produce cardiometabolic disease as a consequence. The aim of this review is to synthesize the work on the mechanisms and metabolic effects of circadian misalignment. The timing of food intake is highlighted as a powerful environmental cue with the potential to destroy or restore the synchrony of circadian rhythms in metabolism.
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Affiliation(s)
- Lauren Pickel
- Translational Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Hoon-Ki Sung
- Translational Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
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Kroll C, Trombelli MCMC, Schultz LF, El Rafihi-Ferreira R, Mastroeni MF. Association of LEP-rs7799039 and ADIPOQ-rs2241766 polymorphisms with sleep duration in preschool age children. Sleep Med 2020; 66:68-75. [DOI: 10.1016/j.sleep.2019.07.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 07/19/2019] [Accepted: 07/19/2019] [Indexed: 11/27/2022]
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Ji Y, Elkin K, Yip J, Guan L, Han W, Ding Y. From circadian clocks to non-alcoholic fatty liver disease. Expert Rev Gastroenterol Hepatol 2019; 13:1107-1112. [PMID: 31645151 DOI: 10.1080/17474124.2019.1684899] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Introduction: The circadian rhythm is an integral regulator of various endocrine processes in the body, including sleep-wake cycles, hormonal regulation, and metabolism. In addition to metabolic, genetic, and environmental factors, a dysregulated circadian rhythm resulting from lifestyle changes has been implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). An accumulating body of evidence also supports strong association between NAFLD and metabolic disorder, the pathogenesis of which is related to periodic fluctuations in hormonal homeostasis. It is clear that endocrine and circadian rhythms are tightly interconnected. Generally, the circadian rhythm regulates flux patterns of physiological functions. The present review will discuss the modulation of bodily processes by the circadian rhythm with specific attention to the regulation of NAFLD by leptin and related hormones.Areas covered: PubMed/MEDLINE was searched for articles related to concomitant occurrence of NAFLD and T2DM between January 1995 and September 2019. Areas covered included epidemiological, physiology and pathophysiology aspects.Expert opinion: NAFLD and NASH are increasingly prevalent and may be largely mitigated with effective lifestyle modification and, potentially, circadian rhythm stabilization. Improved knowledge of the specific pathogenesis of NAFLD in addition to enhanced diagnostic screening tools and prediction of future disease burden is imperative.
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Affiliation(s)
- Yu Ji
- Department of General Surgery, Beijing Luhe Hospital, Capital Medical University, Beijing, China.,Department of Neurosurgery, School of Medicine, Wayne State University, Detroit, MI, USA.,Department of Research & Development Center, John D. Dingell VA Medical Center, Detroit, MI, USA
| | - Kenneth Elkin
- Department of Neurosurgery, School of Medicine, Wayne State University, Detroit, MI, USA
| | - James Yip
- Department of Neurosurgery, School of Medicine, Wayne State University, Detroit, MI, USA
| | - Longfei Guan
- Department of Neurosurgery, School of Medicine, Wayne State University, Detroit, MI, USA.,Department of Research & Development Center, John D. Dingell VA Medical Center, Detroit, MI, USA.,China-America Institute of Neuroscience, Beijing Luhe Hospital, Capital Medical University, Beijing, China
| | - Wei Han
- Department of General Surgery, Beijing Luhe Hospital, Capital Medical University, Beijing, China
| | - Yuchuan Ding
- Department of Neurosurgery, School of Medicine, Wayne State University, Detroit, MI, USA.,Department of Research & Development Center, John D. Dingell VA Medical Center, Detroit, MI, USA
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Laurens C, Simon C, Vernikos J, Gauquelin-Koch G, Blanc S, Bergouignan A. Revisiting the Role of Exercise Countermeasure on the Regulation of Energy Balance During Space Flight. Front Physiol 2019; 10:321. [PMID: 30984019 PMCID: PMC6449861 DOI: 10.3389/fphys.2019.00321] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/11/2019] [Indexed: 01/24/2023] Open
Abstract
A body mass loss has been consistently observed in astronauts. This loss is of medical concern since energy deficit can exacerbate some of the deleterious physiological changes observed during space flight including cardiovascular deconditioning, bone density, muscle mass and strength losses, impaired exercise capacity, and immune deficiency among others. These may jeopardize crew health and performance, a healthy return to Earth and mission’s overall success. In the context of planning for planetary exploration, achieving energy balance during long-term space flights becomes a research and operational priority. The regulation of energy balance and its components in current longer duration missions in space must be re-examined and fully understood. The purpose of this review is to summarize current understanding of how energy intake, energy expenditure, and hence energy balance are regulated in space compared to Earth. Data obtained in both actual and simulated microgravity thus far suggest that the obligatory exercise countermeasures program, rather than the microgravity per se, may be partly responsible for the chronic weight loss in space. Little is known of the energy intake, expenditure, and balance during the intense extravehicular activities which will become increasingly more frequent and difficult. The study of the impact of exercise on energy balance in space also provides further insights on lifestyle modalities such as intensity and frequency of exercise, metabolism, and the regulation of body weight on Earth, which is currently a topic of animated debate in the field of energy and obesity research. While not dismissing the significance of exercise as a countermeasure during space flight, data now challenge the current exercise countermeasure program promoted and adopted for many years by all the International Space Agencies. An alternative exercise approach that has a minimum impact on total energy expenditure in space, while preventing muscle mass loss and other physiological changes, is needed in order to better understand the in-flight regulation of energy balance and estimate daily energy requirements. A large body of data generated on Earth suggests that alternate approaches, such as high intensity interval training (HIIT), in combination or not with sessions of resistive exercise, might fulfill such needs.
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Affiliation(s)
- Claire Laurens
- Université de Strasbourg, Centre National de la Recherche Scientifique, Institut Pluridisciplinaire Hubert Curien UMR 7178, Strasbourg, France.,Centre National d'Etudes Spatiales, Paris, France
| | - Chantal Simon
- Carmen INSERM U1060, Laboratoire de Recherche en Cardiovasculaire, Métabolisme, Diabétologie et Nutrition, Université de Lyon, Lyon, France.,Human Nutrition Research Centre of Rhône-Alpes, Hospices Civils de Lyon, Lyon, France
| | | | | | - Stéphane Blanc
- Université de Strasbourg, Centre National de la Recherche Scientifique, Institut Pluridisciplinaire Hubert Curien UMR 7178, Strasbourg, France
| | - Audrey Bergouignan
- Université de Strasbourg, Centre National de la Recherche Scientifique, Institut Pluridisciplinaire Hubert Curien UMR 7178, Strasbourg, France.,Anschutz Health and Wellness Center, Anschutz Medical Campus, Aurora, CO, United States.,Division of Endocrinology, Metabolism and Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO, United States
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Brain tumor necrosis factor-α mediates anxiety-like behavior in a mouse model of severe obesity. Brain Behav Immun 2019; 77:25-36. [PMID: 30508579 DOI: 10.1016/j.bbi.2018.11.316] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 11/22/2018] [Accepted: 11/28/2018] [Indexed: 12/18/2022] Open
Abstract
Although the high prevalence of anxiety in obesity increasingly emerges as significant risk factor for related severe health complications, the underlying pathophysiological mechanisms remain poorly understood. Considering that chronic inflammation is a key component of obesity and is well known to impact brain function and emotional behavior, we hypothesized that it may similarly contribute to the development of obesity-related anxiety. This hypothesis was experimentally tested by measuring whether chronic food restriction, a procedure known to reduce inflammation, or chronic anti-inflammatory treatment with ibuprofen improved anxiety-like behavior and concomitantly decreased peripheral and/or hippocampal inflammation characterizing a model of severe obesity, the db/db mice. In both experiments, reduced anxiety-like behaviors in the open-field and/or elevated plus-maze were selectively associated with decreased hippocampal tumor necrosis factor-α (TNF-α) mRNA expression. Highlighting the causality of both events, chronic central infusion of the TNF-α blocker etanercept was then shown to be sufficient to improve anxiety-like behavior in db/db mice. Lastly, by measuring the impact of ex-vivo etanercept on hippocampal synaptic processes underlying anxiety-like behaviors, we showed that the anxiolytic effect of central TNF-α blockade likely involved modulation of synaptic transmission within the ventral hippocampus. Altogether, these results uphold the role of brain TNF-α in mediating obesity-related anxiety and provide important clues about how it may modulate brain function and behavior. They may therefore help to introduce novel therapeutic strategies to reduce anxiety associated with inflammatory conditions.
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