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Zhang Y, Szramowski M, Sun S, Henderson GC. Combining albumin deficiency and acute exercise reduces hepatic lipid droplet size in mice. Lipids Health Dis 2023; 22:78. [PMID: 37344835 DOI: 10.1186/s12944-023-01845-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/08/2023] [Indexed: 06/23/2023] Open
Abstract
Hepatic lipid droplets (LDs) are implicated in ectopic lipid accumulation. The core of LDs, triacylglycerol (TAG), is synthesized from the esterification of fatty acids to a glycerol-3-phosphate (G-3-P) backbone. Albumin transports plasma free fatty acids, and previously albumin knockout (Alb-/-) mice were shown to exhibit lower hepatic TAG levels than wildtype (WT). Exercise is a beneficial strategy to alter hepatic metabolism, but its impacts on reducing hepatic lipids are far from satisfactory. The aim of this study was to investigate the combined effect of albumin deficiency and acute exercise on hepatic LDs. Eight-week-old male Alb-/- and WT mice were divided into sedentary and exercise groups. Exercised mice performed a 30-min high-intensity exercise bout. Results showed that sedentary Alb-/- mice had smaller hepatic LDs (P < 0.0001), associated with mitochondria, while WT mice exhibited larger LDs, surrounded by glycogen granules. Following acute exercise, hepatic LDs in Alb-/- mice reduced by 40% in size, while in WT increased by 14% (P < 0.0001). The maintenance of WT hepatic LDs was associated with elevated G-3-P level (P < 0.05), potentially derived from glycogen (R = -0.32, %change in glycogen versus LD content, P < 0.05). The reduction in Alb-/- mice LDs after exercise was possibly due to their low glycogen level. In conclusion, Alb-/- mice exhibited an enhanced capacity for reducing hepatic LD size and content in response to exercise. These findings suggest that modulating albumin's functions combined with exercise could be a potential strategy to reduce ectopic lipid deposition in the liver.
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Affiliation(s)
- Yi Zhang
- Department of Nutrition Science, Purdue University, 700 Mitch Daniels Blvd., West Lafayette, IN, 47907, USA
| | - Mirandia Szramowski
- Department of Nutrition Science, Purdue University, 700 Mitch Daniels Blvd., West Lafayette, IN, 47907, USA
| | - Shuhan Sun
- Department of Nutrition Science, Purdue University, 700 Mitch Daniels Blvd., West Lafayette, IN, 47907, USA
| | - Gregory C Henderson
- Department of Nutrition Science, Purdue University, 700 Mitch Daniels Blvd., West Lafayette, IN, 47907, USA.
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2
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Willis SA, Malaikah S, Parry S, Bawden S, Ennequin G, Sargeant JA, Yates T, Webb DR, Davies MJ, Stensel DJ, Aithal GP, King JA. The effect of acute and chronic exercise on hepatic lipid composition. Scand J Med Sci Sports 2023; 33:550-568. [PMID: 36610000 DOI: 10.1111/sms.14310] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 12/06/2022] [Accepted: 01/04/2023] [Indexed: 01/09/2023]
Abstract
Exercise is recommended for those with, or at risk of nonalcoholic fatty liver disease (NAFLD), owing to beneficial effects on hepatic steatosis and cardiometabolic risk. Whilst exercise training reduces total intrahepatic lipid in people with NAFLD, accumulating evidence indicates that exercise may also modulate hepatic lipid composition. This metabolic influence is important as the profile of saturated (SFA), monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA) dramatically affect the metabolic consequences of hepatic lipid accumulation; with SFA being especially lipotoxic. Relatedly, obesity and NAFLD are associated with hepatic PUFA depletion and elevated SFA. This review summarizes the acute (single bout) and chronic (exercise training) effects of exercise on hepatic lipid composition in rodents (acute studies: n = 3, chronic studies: n = 13) and humans (acute studies: n = 1, chronic studies: n = 3). An increased proportion of hepatic PUFA after acute and chronic exercise is the most consistent finding of this review. Mechanistically, this may relate to an enhanced uptake of adipose-derived PUFA (reflecting habitual diet), particularly in rodents. A relative decrease in the proportion of hepatic MUFA after chronic exercise is also documented repeatedly, particularly in rodent models with elevated hepatic MUFA. This outcome is related to decreased hepatic stearoyl-CoA desaturase-1 activity in some studies. Findings regarding hepatic SFA are less consistent and limited by the absence of metabolic challenge in rodent models. These findings require confirmation in well-controlled interventions in people with NAFLD. These studies will be facilitated by recently validated magnetic resonance spectroscopy techniques, able to precisely quantify hepatic lipid composition in vivo.
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Affiliation(s)
- Scott A Willis
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and the University of Leicester, Leicester, UK
| | - Sundus Malaikah
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and the University of Leicester, Leicester, UK
| | - Siôn Parry
- Warwickshire Institute for the Study of Diabetes, Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
| | - Stephen Bawden
- Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, UK.,NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
| | - Gaël Ennequin
- Laboratory of Metabolic Adaptations to Exercise Under Physiological and Pathological Conditions (AME2P), Université of Clermont Auvergne, Clermont-Ferrand, France
| | - Jack A Sargeant
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and the University of Leicester, Leicester, UK.,Diabetes Research Centre, University of Leicester, Leicester, UK
| | - Thomas Yates
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and the University of Leicester, Leicester, UK.,Diabetes Research Centre, University of Leicester, Leicester, UK
| | - David R Webb
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and the University of Leicester, Leicester, UK.,Diabetes Research Centre, University of Leicester, Leicester, UK
| | - Melanie J Davies
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and the University of Leicester, Leicester, UK.,Diabetes Research Centre, University of Leicester, Leicester, UK
| | - David J Stensel
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and the University of Leicester, Leicester, UK.,Faculty of Sport Sciences, Waseda University, Tokorozawa, Japan
| | - Guruprasad P Aithal
- NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK.,Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - James A King
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and the University of Leicester, Leicester, UK
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Henderson GC. Plasma Free Fatty Acid Concentration as a Modifiable Risk Factor for Metabolic Disease. Nutrients 2021; 13:nu13082590. [PMID: 34444750 PMCID: PMC8402049 DOI: 10.3390/nu13082590] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/18/2021] [Accepted: 07/27/2021] [Indexed: 02/07/2023] Open
Abstract
Plasma free fatty acid (FFA) concentration is elevated in obesity, insulin resistance (IR), non-alcoholic fatty liver disease (NAFLD), type 2 diabetes (T2D), and related comorbidities such as cardiovascular disease (CVD). Furthermore, experimentally manipulating plasma FFA in the laboratory setting modulates metabolic markers of these disease processes. In this article, evidence is presented indicating that plasma FFA is a disease risk factor. Elevations of plasma FFA can promote ectopic lipid deposition, IR, as well as vascular and cardiac dysfunction. Typically, elevated plasma FFA results from accelerated adipose tissue lipolysis, caused by a high adipose tissue mass, adrenal hormones, or other physiological stressors. Reducing an individual’s postabsorptive and postprandial plasma FFA concentration is expected to improve health. Lifestyle change could provide a significant opportunity for plasma FFA reduction. Various factors can impact plasma FFA concentration, such as chronic restriction of dietary energy intake and weight loss, as well as exercise, sleep quality and quantity, and cigarette smoking. In this review, consideration is given to multiple factors which lead to plasma FFA elevation and subsequent disruption of metabolic health. From considering a variety of medical conditions and lifestyle factors, it becomes clear that plasma FFA concentration is a modifiable risk factor for metabolic disease.
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Affiliation(s)
- Gregory C Henderson
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
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Henderson GC, Meyer JM. Transient elevation of triacylglycerol content in the liver: a fundamental component of the acute response to exercise. J Appl Physiol (1985) 2021; 130:1293-1303. [PMID: 33475457 DOI: 10.1152/japplphysiol.00930.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Exercise is well appreciated as a therapeutic approach to improve health. Although chronic exercise training can change metabolism, even a single exercise session can have significant effects upon metabolism. Responses of adipose tissue lipolysis and skeletal muscle triacylglycerol (TAG) utilization have been well appreciated as components of the acute exercise response. However, there are other central components of the physiological response to be considered, as well. A robust and growing body of literature depicts a rapid responsiveness of hepatic TAG content to single bouts of exercise, and there is a remaining need to incorporate this information into our overall understanding of how exercise affects the liver. TAG content in the liver increases during an exercise session and can continue to rise for a few hours afterwards, followed by a fairly rapid return to baseline. Here, we summarize evidence that rapid responsiveness of hepatic TAG content to metabolic stress is a fundamental component of the exercise response. Adipose tissue lipolysis and plasma free fatty acid concentration are likely the major metabolic controllers of enhanced lipid storage in the liver after each exercise bout, and we discuss nutritional impacts as well as health implications. Although traditionally clinicians would be merely concerned with hepatic lipids in overnight-fasted, rested individuals, it is now apparent that the content of hepatic TAG fluctuates in response to metabolic challenges such as exercise, and these responses likely exert significant impacts on health and cellular homeostasis.
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Affiliation(s)
| | - Juliauna M. Meyer
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana
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