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Friedman MI, Sørensen TIA, Taubes G, Lund J, Ludwig DS. Trapped fat: Obesity pathogenesis as an intrinsic disorder in metabolic fuel partitioning. Obes Rev 2024. [PMID: 38961319 DOI: 10.1111/obr.13795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 05/24/2024] [Accepted: 06/13/2024] [Indexed: 07/05/2024]
Abstract
Our understanding of the pathophysiology of obesity remains at best incomplete despite a century of research. During this time, two alternative perspectives have helped shape thinking about the etiology of the disorder. The currently prevailing view holds that excessive fat accumulation results because energy intake exceeds energy expenditure, with excessive food consumption being the primary cause of the imbalance. The other perspective attributes the initiating cause of obesity to intrinsic metabolic defects that shift fuel partitioning from pathways for mobilization and oxidation to those for synthesis and storage. The resulting reduction in fuel oxidation and trapping of energy in adipose tissue drives a compensatory increase in energy intake and, under some conditions, a decrease in expenditure. This theory of obesity pathogenesis has historically garnered relatively less attention despite its pedigree. Here, we present an updated comprehensive formulation of the fuel partitioning theory, focused on evidence gathered over the last 80 years from major animal models of obesity showing a redirection of fuel fluxes from oxidation to storage and accumulation of excess body fat with energy intake equal to or even less than that of lean animals. The aim is to inform current discussions about the etiology of obesity and by so doing, help lay new foundations for the design of more efficacious approaches to obesity research, treatment and prevention.
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Affiliation(s)
| | - Thorkild I A Sørensen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
- Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
- Center for Childhood Health, Copenhagen, Denmark
| | | | - Jens Lund
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - David S Ludwig
- New Balance Foundation Obesity Prevention Center, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
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Kurotaki Y, Sakai N, Miyazaki T, Hosonuma M, Sato Y, Karakawa A, Chatani M, Myers M, Suzawa T, Negishi-Koga T, Kamijo R, Miyazaki A, Maruoka Y, Takami M. Effects of lipid metabolism on mouse incisor dentinogenesis. Sci Rep 2020; 10:5102. [PMID: 32198436 PMCID: PMC7083963 DOI: 10.1038/s41598-020-61978-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 03/03/2020] [Indexed: 01/09/2023] Open
Abstract
Tooth formation can be affected by various factors, such as oral disease, drug administration, and systemic illness, as well as internal conditions including dentin formation. Dyslipidemia is an important lifestyle disease, though the relationship of aberrant lipid metabolism with tooth formation has not been clarified. This study was performed to examine the effects of dyslipidemia on tooth formation and tooth development. Dyslipidemia was induced in mice by giving a high-fat diet (HFD) for 12 weeks. Additionally, LDL receptor-deficient (Ldlr−/−) strain mice were used to analyze the effects of dyslipidemia and lipid metabolism in greater detail. In the HFD-fed mice, incisor elongation was decreased and pulp was significantly narrowed, while histological findings revealed disappearance of predentin. In Ldlr−/− mice fed regular chow, incisor elongation showed a decreasing trend and pulp a narrowing trend, while predentin changes were unclear. Serum lipid levels were increased in the HFD-fed wild-type (WT) mice, while Ldlr−/− mice given the HFD showed the greatest increase. These results show important effects of lipid metabolism, especially via the LDL receptor, on tooth homeostasis maintenance. In addition, they suggest a different mechanism for WT and Ldlr−/− mice, though the LDL receptor pathway may not be the only factor involved.
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Affiliation(s)
- Yutaro Kurotaki
- Division of Community-Based Comprehensive Dentistry, Department of Special Needs Dentistry, School of Dentistry, Showa University, 2-1-1 Kitasenzoku, Ota, Tokyo, 145-8515, Japan.,Department of Pharmacology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Pharmacological Research Center, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Nobuhiro Sakai
- Department of Pharmacology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan. .,Pharmacological Research Center, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.
| | - Takuro Miyazaki
- Department of Biochemistry, School of Medicine, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Masahiro Hosonuma
- Department of Pharmacology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Pharmacological Research Center, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Division of Rheumatology, Department of Medicine, School of Medicine, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Yurie Sato
- Department of Pharmacology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Pharmacological Research Center, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Division of Dentistry for Persons with Disabilities, School of Dentistry, Showa University, 2-1-1 Kitasenzoku, Ota, Tokyo, 145-8515, Japan
| | - Akiko Karakawa
- Department of Pharmacology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Pharmacological Research Center, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Masahiro Chatani
- Department of Pharmacology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Pharmacological Research Center, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Mie Myers
- Division of Community-Based Comprehensive Dentistry, Department of Special Needs Dentistry, School of Dentistry, Showa University, 2-1-1 Kitasenzoku, Ota, Tokyo, 145-8515, Japan
| | - Tetsuo Suzawa
- Department of Biochemistry, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Takako Negishi-Koga
- Department of Pharmacology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Pharmacological Research Center, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Division of Mucosal Barriology, International Research and Development Center for Mucosal vaccines, The Institute of Medical Science, The Institute of Medical Science The University of Tokyo, 4-6-1 Shirokanedai, Minato, Tokyo, 108-8639, Japan
| | - Ryutaro Kamijo
- Department of Biochemistry, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Akira Miyazaki
- Department of Biochemistry, School of Medicine, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Yasubumi Maruoka
- Division of Community-Based Comprehensive Dentistry, Department of Special Needs Dentistry, School of Dentistry, Showa University, 2-1-1 Kitasenzoku, Ota, Tokyo, 145-8515, Japan
| | - Masamichi Takami
- Department of Pharmacology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan. .,Pharmacological Research Center, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.
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Alexander J, Chang GQ, Dourmashkin JT, Leibowitz SF. Distinct phenotypes of obesity-prone AKR/J, DBA2J and C57BL/6J mice compared to control strains. Int J Obes (Lond) 2006; 30:50-9. [PMID: 16231032 DOI: 10.1038/sj.ijo.0803110] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To characterize and compare three obesity-prone inbred strains, AKR/J, DBA/2J and C57BL/6J, to three control strains, C3H/HeJ, BALB/cByJ and C57L/J, selected based on their normal eating patterns and moderate weight gain on high-calorie diets. METHODS AND PROCEDURES These six strains were examined at 5 weeks of age while still of normal body weight, and they were maintained for 1 day or 3 weeks on different feeding paradigms with macronutrient diets. Measurements were taken of macronutrient intake, body weight and body fat accrual, circulating hormones and metabolites, and the hypothalamic peptide, galanin. RESULTS The three control strains each selected a balanced diet with 50% carbohydrate and 15-25% fat when given a choice of macronutrients, and they had similar, normal range of scores for the measures of body weight, adiposity, the hormones, insulin and leptin, and the metabolites, glucose and triglycerides. When compared to this control baseline, the obesity-prone strains with similar total caloric intake to controls selected a diet with significantly more fat (30-40%) and less carbohydrate (<40%). They also had greater adiposity, with the largest differences detected for the AKR/J and DBA/2J strains. These two obesity-prone strains compared to control strains had elevated levels of insulin and leptin. They also had higher triglyceride levels and increased expression and levels of galanin in the hypothalamic paraventricular nucleus. A very different pattern was detected in the obesity-prone C57BL/6J strain, which exhibited a stronger preference for protein as well as fat, normal levels of insulin, leptin and triglycerides, hyperglycemia relative to all other strains, and a small increase in galanin. CONCLUSION These comparisons to control strains revealed a distinct phenotype in the two obesity-prone strains, AKR/J and DBA/2J, which is very similar to that described in obesity-prone, outbred rats. They also identified a clearly different phenotype in the obesity-prone C57BL/6J strain.
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Affiliation(s)
- J Alexander
- The Rockefeller University, New York, NY 10021, USA
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Leibowitz SF, Chang GQ, Dourmashkin JT, Yun R, Julien C, Pamy PP. Leptin secretion after a high-fat meal in normal-weight rats: strong predictor of long-term body fat accrual on a high-fat diet. Am J Physiol Endocrinol Metab 2006; 290:E258-67. [PMID: 16403782 DOI: 10.1152/ajpendo.00609.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The objective of this study was to investigate meal-related endocrine changes that permit one to identify Sprague-Dawley rats at normal weight that are prone (OP) vs. resistant (OR) to obesity. In blood collected via chronic cardiac catheters, a 2-h high-fat meal (HFM, 50% fat, 40 kcal) at dark onset caused a significant increase in leptin, insulin, and triglycerides compared with premeal levels. Similar to patterns in already obese compared with lean rats on a high-fat diet, these meal-induced endocrine changes in normal-weight rats on lab chow were almost twofold larger in OP rats that, compared with OR rats, subsequently accumulated 100% more fat mass on a chronic high-fat diet. These exaggerated endocrine changes were similarly observed in blood collected using a simpler tail vein puncture procedure. In three separate experiments, the HFM-induced rise in leptin was found to be the strongest, positive correlate (r = +0.58, +0.62 and +0.64) of long-term body fat accrual. The lowest (2-5 ng/ml) vs. highest (6-9 ng/ml) scores for this post-HFM leptin measurement identified distinct OR and OP subgroups, respectively, when they were similar in body weight (340-350 g), premeal leptin (2.6-3.4 ng/ml), and meal size (40 kcal). Subsequent tests in these normal-weight OP rats revealed a distinct characteristic compared with OR rats, namely, exaggerated HFM-induced rise in expression of the orexigenic peptide galanin in the paraventricular nucleus. Thus, with this HFM-induced leptin measurement, OP rats can be identified while still at normal weight and then investigated for mechanisms that contribute to their excessive body fat accrual on a high-fat diet.
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Affiliation(s)
- S F Leibowitz
- The Rockefeller University, 1230 York Ave., New York, NY, USA.
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Riccardi G, Giacco R, Rivellese AA. Dietary fat, insulin sensitivity and the metabolic syndrome. Clin Nutr 2004; 23:447-56. [PMID: 15297079 DOI: 10.1016/j.clnu.2004.02.006] [Citation(s) in RCA: 432] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Accepted: 02/16/2004] [Indexed: 11/24/2022]
Abstract
Insulin resistance is the pathogenetic link underlying the different metabolic abnormalities clustering in the metabolic syndrome. It can be induced by different environmental factors, including dietary habits. Consumption of energy-dense/high fat diets is strongly and positively associated with overweight that, in turn, deteriorates insulin sensitivity, particularly when the excess of body fat is located in abdominal region. Nevertheless the link between fat intake and overweight is not limited to the high-energy content of fatty foods; the ability to oxidize dietary fat is impaired in some individuals genetically predisposed to obesity. Insulin sensitivity is also affected by the quality of dietary fat, independently of its effects on body weight. Epidemiological evidence and intervention studies clearly show that in humans saturated fat significantly worsen insulin-resistance, while monounsaturated and polyunsaturated fatty acids improve it through modifications in the composition of cell membranes which reflect at least in part dietary fat composition. A recent multicenter study (KANWU) has shown that shifting from a diet rich in saturated fatty acids to one rich in monounsaturated fat improves insulin sensitivity in healthy people while a moderate alpha-3 fatty acids supplementation does not affect insulin sensitivity. There are also other features of the metabolic syndrome that are influenced by different types of fat, particularly blood pressure and plasma lipid levels. Most studies show that alpha-3 fatty acids reduce blood pressure in hypertensive but not in normotensive subjects while shifting from saturated to monounsaturated fat intake reduces diastolic blood pressure. In relation to lipid abnormalities alpha-3 fatty acids reduce plasma triglyceride levels but in parallel, increase LDL cholesterol. Substitution of unsaturated fat for saturated fat not only reduces LDL cholesterol but contributes also to reduce plasma triglycerides in insulin resistant individuals. In conclusion, there is evidence available in humans indicating that dietary fat quality influences insulin sensitivity and associated metabolic abnormalities. Therefore, prevention of the metabolic syndrome has to be targeted: (1) to correct overweight by reducing the energy density of the habitual diet (i.e., fat intake) and (2) to improve insulin sensitivity and associated metabolic abnormalities through a reduction of dietary saturated fat, partially replaced, when appropriate, by monounsaturated and polyunsaturated fats.
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Affiliation(s)
- G Riccardi
- Department of Clinical and Experimental Medicine, "FedericoII" University, Medical School, Via S Pansini 5, 80131, Napoli, Italy.
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