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Zheng D, Hong X, He X, Lin J, Fan S, Wu J, Liang Z, Chen S, Yan L, Ren M, Wang W. Intermittent Fasting-Improved Glucose Homeostasis Is Not Entirely Dependent on Caloric Restriction in db/db Male Mice. Diabetes 2024; 73:864-878. [PMID: 38502858 PMCID: PMC11109801 DOI: 10.2337/db23-0157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 03/08/2024] [Indexed: 03/21/2024]
Abstract
Intermittent fasting (IF), which involves prolonged fasting intervals accompanied by caloric restriction (CR), is an effective dietary treatment for obesity and diabetes. Although IF offers many benefits, it is difficult to determine whether these benefits are the consequences of CR. Every-other-day feeding (EODF) is a commonly used IF research model. This study was designed to identify factors, in addition to CR, responsible for the effects of EODF and the possible underlying mechanisms. Diabetic db/db mice were divided into three groups: ad libitum (AL), meal feeding (MF), and EODF. The MF model was used to attain a level of CR comparable to that of EODF, with food distribution evenly divided between 10:00 a.m. and 6:00 p.m., thereby minimizing the fasting interval. EODF yielded greater improvements in glucose homeostasis than MF in db/db mice by reducing fasting glucose levels and enhancing glucose tolerance. However, these effects on glucose metabolism were less pronounced in lean mice. Furthermore, ubiquitination of the liver-specific glucocorticoid (GC) receptor (GR) facilitated its degradation and downregulation of Kruppel-like factor 9 (KLF9), which ultimately suppressed liver gluconeogenesis in diabetic EODF mice. Although GR and KLF9 might mediate the metabolic benefits of EODF, the potential benefits of EODF might be limited by elevated serum GC levels in diabetic EODF mice. Overall, this study suggests that the metabolic benefits of EODF in improving glucose homeostasis are independent of CR, possibly because of the downstream effects of liver-specific GR degradation. ARTICLE HIGHLIGHTS
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Affiliation(s)
- Dinghao Zheng
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Clinical Research Center for Metabolic Diseases, Guangzhou, China
| | - Xiaosi Hong
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Clinical Research Center for Metabolic Diseases, Guangzhou, China
| | - Xiaodan He
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Clinical Research Center for Metabolic Diseases, Guangzhou, China
| | - Jianghong Lin
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Clinical Research Center for Metabolic Diseases, Guangzhou, China
| | - Shujin Fan
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Clinical Research Center for Metabolic Diseases, Guangzhou, China
| | - Jinli Wu
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Clinical Research Center for Metabolic Diseases, Guangzhou, China
| | - Zhuoxian Liang
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Clinical Research Center for Metabolic Diseases, Guangzhou, China
| | - Sifan Chen
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Nanhai Translational Innovation Center of Precision Immunology, Sun Yat-sen Memorial Hospital, Foshan, China
| | - Li Yan
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Clinical Research Center for Metabolic Diseases, Guangzhou, China
| | - Meng Ren
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Clinical Research Center for Metabolic Diseases, Guangzhou, China
| | - Wei Wang
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Clinical Research Center for Metabolic Diseases, Guangzhou, China
- Department of Endocrinology, Shenshan Medical Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
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Green CL, Lamming DW, Fontana L. Molecular mechanisms of dietary restriction promoting health and longevity. Nat Rev Mol Cell Biol 2022; 23:56-73. [PMID: 34518687 PMCID: PMC8692439 DOI: 10.1038/s41580-021-00411-4] [Citation(s) in RCA: 243] [Impact Index Per Article: 121.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2021] [Indexed: 02/08/2023]
Abstract
Dietary restriction with adequate nutrition is the gold standard for delaying ageing and extending healthspan and lifespan in diverse species, including rodents and non-human primates. In this Review, we discuss the effects of dietary restriction in these mammalian model organisms and discuss accumulating data that suggest that dietary restriction results in many of the same physiological, metabolic and molecular changes responsible for the prevention of multiple ageing-associated diseases in humans. We further discuss how different forms of fasting, protein restriction and specific reductions in the levels of essential amino acids such as methionine and the branched-chain amino acids selectively impact the activity of AKT, FOXO, mTOR, nicotinamide adenine dinucleotide (NAD+), AMP-activated protein kinase (AMPK) and fibroblast growth factor 21 (FGF21), which are key components of some of the most important nutrient-sensing geroprotective signalling pathways that promote healthy longevity.
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Affiliation(s)
- Cara L Green
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
- William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Dudley W Lamming
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
- William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Luigi Fontana
- Charles Perkins Center, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia.
- Department of Endocrinology, Royal Prince Alfred Hospital, Sydney, NSW, Australia.
- Department of Clinical and Experimental Sciences, Brescia University School of Medicine, Brescia, Italy.
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Clifton KK, Ma CX, Fontana L, Peterson LL. Intermittent fasting in the prevention and treatment of cancer. CA Cancer J Clin 2021; 71:527-546. [PMID: 34383300 DOI: 10.3322/caac.21694] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/06/2021] [Accepted: 07/09/2021] [Indexed: 12/15/2022] Open
Abstract
Chronic caloric restriction (CR) has powerful anticarcinogenic actions in both preclinical and clinical studies but may be difficult to sustain. As an alternative to CR, there has been growing interest in intermittent fasting (IF) in both the scientific and lay community as a result of promising study results, mainly in experimental animal models. According to a survey by the International Food Information Council Foundation, IF has become the most popular diet in the last year, and patients with cancer are seeking advice from oncologists about its beneficial effects for cancer prevention and treatment. However, as discussed in this review, results from IF studies in rodents are controversial and suggest potential detrimental effects in certain oncologic conditions. The effects of IF on human cancer incidence and prognosis remain unknown because of a lack of high-quality randomized clinical trials. Preliminary studies suggest that prolonged fasting in some patients who have cancer is safe and potentially capable of decreasing chemotherapy-related toxicity and tumor growth. However, because additional trials are needed to elucidate the risks and benefits of fasting for patients with cancer, the authors would not currently recommend patients undergoing active cancer treatment partake in IF outside the context of a clinical trial. IF may be considered in adults seeking cancer-prevention benefits through means of weight management, but whether IF itself affects cancer-related metabolic and molecular pathways remains unanswered.
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Affiliation(s)
- Katherine K Clifton
- School of Medicine, Division of Medical Oncology, Washington University in St Louis, St Louis, Missouri
| | - Cynthia X Ma
- School of Medicine, Division of Medical Oncology, Washington University in St Louis, St Louis, Missouri
| | - Luigi Fontana
- Charles Perkins Center, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
- Department of Endocrinology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
- Department of Clinical and Experimental Sciences, Brescia University, Brescia, Italy
| | - Lindsay L Peterson
- School of Medicine, Division of Medical Oncology, Washington University in St Louis, St Louis, Missouri
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Tan C, Liu X, Peng W, Wang H, Zhou W, Jiang J, Wei X, Mo L, Chen Y, Chen L. Seizure-induced impairment in neuronal ketogenesis: Role of zinc-α2-glycoprotein in mitochondria. J Cell Mol Med 2020; 24:6833-6845. [PMID: 32340079 PMCID: PMC7299723 DOI: 10.1111/jcmm.15337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 01/11/2020] [Accepted: 04/12/2020] [Indexed: 12/14/2022] Open
Abstract
Ketone bodies (KBs) were known to suppress seizure. Untraditionally, neurons were recently reported to utilize fatty acids and produce KBs, but the effect of seizure on neuronal ketogenesis has not been researched. Zinc‐α2‐glycoprotein (ZAG) was reported to suppress seizure via unclear mechanism. Interestingly, ZAG was involved in fatty acid β‐oxidation and thus may exert anti‐epileptic effect by promoting ketogenesis. However, this promotive effect of ZAG on neuronal ketogenesis has not been clarified. In this study, we performed immunoprecipitation and mass spectrometry to identify potential interaction partners with ZAG. The mechanisms of how ZAG translocated into mitochondria were determined by quantitative coimmunoprecipitation after treatment with apoptozole, a heat shock cognate protein 70 (HSC70) inhibitor. ZAG level was modulated by lentivirus in neurons or adeno‐associated virus in rat brains. Seizure models were induced by magnesium (Mg2+)‐free artificial cerebrospinal fluid in neurons or intraperitoneal injection of pentylenetetrazole kindling in rats. Ketogenesis was determined by cyclic thio‐NADH method in supernatant of neurons or brain homogenate. The effect of peroxisome proliferator–activated receptor γ (PPARγ) on ZAG expression was examined by Western blot, quantitative real‐time polymerase chain reaction (qRT‐PCR) and chromatin immunoprecipitation qRT‐PCR. We found that seizure induced ketogenesis deficiency via a ZAG‐dependent mechanism. ZAG entered mitochondria through a HSC70‐dependent mechanism, promoted ketogenesis by binding to four β‐subunits of long‐chain L‐3‐hydroxyacyl‐CoA dehydrogenase (HADHB) and alleviated ketogenesis impairment in a neuronal seizure model and pentylenetetrazole‐kindled epileptic rats. Additionally, PPARγ activation up‐regulated ZAG expression by binding to promoter region of AZGP1 gene and promoted ketogenesis through a ZAG‐dependent mechanism.
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Affiliation(s)
- Changhong Tan
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xi Liu
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Wuxue Peng
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Hui Wang
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Wen Zhou
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Jin Jiang
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xin Wei
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Lijuan Mo
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yangmei Chen
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Lifen Chen
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
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Tanegashima K, Sato-Miyata Y, Funakoshi M, Nishito Y, Aigaki T, Hara T. Epigenetic regulation of the glucose transporter gene Slc2a1 by β-hydroxybutyrate underlies preferential glucose supply to the brain of fasted mice. Genes Cells 2016; 22:71-83. [PMID: 27935189 DOI: 10.1111/gtc.12456] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 11/07/2016] [Indexed: 02/02/2023]
Abstract
We carried out liquid chromatography-tandem mass spectrometry analysis of metabolites in mice. Those metabolome data showed that hepatic glucose content is reduced, but that brain glucose content is unaffected, during fasting, consistent with the priority given to brain glucose consumption during fasting. The molecular mechanisms for this preferential glucose supply to the brain are not fully understood. We also showed that the fasting-induced production of the ketone body β-hydroxybutyrate (β-OHB) enhances expression of the glucose transporter gene Slc2a1 (Glut1) via histone modification. Upon β-OHB treatment, Slc2a1 expression was up-regulated, with a concomitant increase in H3K9 acetylation at the critical cis-regulatory region of the Slc2a1 gene in brain microvascular endothelial cells and NB2a neuronal cells, shown by quantitative PCR analysis and chromatin immunoprecipitation assay. CRISPR/Cas9-mediated disruption of the Hdac2 gene increased Slc2a1 expression, suggesting that it is one of the responsible histone deacetylases (HDACs). These results confirm that β-OHB is a HDAC inhibitor and show that β-OHB plays an important role in fasting-induced epigenetic activation of a glucose transporter gene in the brain.
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Affiliation(s)
- Kosuke Tanegashima
- Stem Cell Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan
| | - Yukiko Sato-Miyata
- Cellular Genetics Laboratory, Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Masabumi Funakoshi
- Cellular Genetics Laboratory, Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Yasumasa Nishito
- Center for Basic Technology Research, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan
| | - Toshiro Aigaki
- Cellular Genetics Laboratory, Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Takahiko Hara
- Stem Cell Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan.,Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
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Wueest S, Item F, Boyle CN, Jirkof P, Cesarovic N, Ellingsgaard H, Böni-Schnetzler M, Timper K, Arras M, Donath MY, Lutz TA, Schoenle EJ, Konrad D. Interleukin-6 contributes to early fasting-induced free fatty acid mobilization in mice. Am J Physiol Regul Integr Comp Physiol 2014; 306:R861-7. [DOI: 10.1152/ajpregu.00533.2013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Contracting muscle releases interleukin-6 (IL-6) enabling the metabolic switch from carbohydrate to fat utilization. Similarly, metabolism is switched during transition from fed to fasting state. Herein, we examined a putative role for IL-6 in the metabolic adaptation to normal fasting. In lean C57BL/6J mice, 6 h of food withdrawal increased gene transcription levels of IL-6 in skeletal muscle but not in white adipose tissue. Concomitantly, circulating IL-6 and free fatty acid (FFA) levels were significantly increased, whereas respiratory quotient (RQ) was reduced in 6-h fasted mice. In white adipose tissue, phosphorylation of hormone-sensitive lipase (HSL) was increased on fasting, indicating increased lipolysis. Intriguingly, fasting-induced increase in circulating IL-6 levels and parallel rise in FFA concentration were absent in obese and glucose-intolerant mice. A causative role for IL-6 in the physiological adaptation to fasting was further supported by the fact that fasting-induced increase in circulating FFA levels was significantly blunted in lean IL-6 knockout (KO) and lean C57BL/6J mice treated with neutralizing IL-6 antibody. Consistently, phosphorylation of HSL was significantly reduced in adipose tissue of IL-6-depleted mice. Hence, our findings suggest a novel role for IL-6 in energy supply during early fasting.
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Affiliation(s)
- Stephan Wueest
- Department of Pediatric Endocrinology and Diabetology and
- Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Flurin Item
- Department of Pediatric Endocrinology and Diabetology and
- Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Christina N. Boyle
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
| | - Paulin Jirkof
- Division of Surgical Research, University Hospital Zurich, Zurich Switzerland
| | - Nikola Cesarovic
- Division of Surgical Research, University Hospital Zurich, Zurich Switzerland
| | - Helga Ellingsgaard
- Division of Endocrinology, Diabetes & Metabolism and Department of Biomedicine, University Hospital and University of Basel, Basel, Switzerland
| | - Marianne Böni-Schnetzler
- Division of Endocrinology, Diabetes & Metabolism and Department of Biomedicine, University Hospital and University of Basel, Basel, Switzerland
| | - Katharina Timper
- Division of Endocrinology, Diabetes & Metabolism and Department of Biomedicine, University Hospital and University of Basel, Basel, Switzerland
| | - Margarete Arras
- Division of Surgical Research, University Hospital Zurich, Zurich Switzerland
| | - Marc Y. Donath
- Division of Endocrinology, Diabetes & Metabolism and Department of Biomedicine, University Hospital and University of Basel, Basel, Switzerland
| | - Thomas A. Lutz
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland; and
- Institute of Laboratory Animal Science, University of Zurich, Zurich, Switzerland
| | - Eugen J. Schoenle
- Department of Pediatric Endocrinology and Diabetology and
- Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Daniel Konrad
- Department of Pediatric Endocrinology and Diabetology and
- Children's Research Center, University Children's Hospital, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland; and
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Hakvoort TBM, Moerland PD, Frijters R, Sokolović A, Labruyère WT, Vermeulen JLM, Ver Loren van Themaat E, Breit TM, Wittink FRA, van Kampen AHC, Verhoeven AJ, Lamers WH, Sokolović M. Interorgan coordination of the murine adaptive response to fasting. J Biol Chem 2011; 286:16332-43. [PMID: 21393243 DOI: 10.1074/jbc.m110.216986] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Starvation elicits a complex adaptive response in an organism. No information on transcriptional regulation of metabolic adaptations is available. We, therefore, studied the gene expression profiles of brain, small intestine, kidney, liver, and skeletal muscle in mice that were subjected to 0-72 h of fasting. Functional-category enrichment, text mining, and network analyses were employed to scrutinize the overall adaptation, aiming to identify responsive pathways, processes, and networks, and their regulation. The observed transcriptomics response did not follow the accepted "carbohydrate-lipid-protein" succession of expenditure of energy substrates. Instead, these processes were activated simultaneously in different organs during the entire period. The most prominent changes occurred in lipid and steroid metabolism, especially in the liver and kidney. They were accompanied by suppression of the immune response and cell turnover, particularly in the small intestine, and by increased proteolysis in the muscle. The brain was extremely well protected from the sequels of starvation. 60% of the identified overconnected transcription factors were organ-specific, 6% were common for 4 organs, with nuclear receptors as protagonists, accounting for almost 40% of all transcriptional regulators during fasting. The common transcription factors were PPARα, HNF4α, GCRα, AR (androgen receptor), SREBP1 and -2, FOXOs, EGR1, c-JUN, c-MYC, SP1, YY1, and ETS1. Our data strongly suggest that the control of metabolism in four metabolically active organs is exerted by transcription factors that are activated by nutrient signals and serves, at least partly, to prevent irreversible brain damage.
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Affiliation(s)
- Theodorus B M Hakvoort
- Tytgat Institute for Liver and Intestinal Research (formerly AMC Liver Center), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Bergman BC, Jensen DR, Pulawa LK, Ferreira LDMCB, Eckel RH. Fasting decreases free fatty acid turnover in mice overexpressing skeletal muscle lipoprotein lipase. Metabolism 2006; 55:1481-7. [PMID: 17046550 DOI: 10.1016/j.metabol.2006.06.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Accepted: 06/22/2006] [Indexed: 10/24/2022]
Abstract
Skeletal muscle lipoprotein lipase (LPL) overexpression in mice results in whole-body insulin resistance and increased intramuscular triglyceride stores, but decreased plasma triglyceride concentration and unchanged plasma free fatty acid (FFA) concentration. The effects of skeletal muscle LPL overexpression and fasting duration on FFA kinetics are unknown. Transgenic mice with muscle-specific LPL overexpression (MCKhLPL) and control mice (Con) were studied at rest during a 50-minute constant infusion of [9,10- 3H]palmitate to determine FFA kinetics after both 4 and 16 hours of fasting. FFA concentration was not different between groups after the 4-hour (Con, 0.80 +/- 0.06 mmol/L; MCKhLPL, 0.83 +/- 0.07 mmol/L) and 16-hour (Con, 0.83 +/- 0.04 mmol/L; MCKhLPL, 0.80 +/- 0.07 mmol/L) fast. FFA turnover (Ra) was not significantly different between MCKhLPL and Con groups after the 4-hour fast (Con Ra = 2.52 +/- 0.36 micromol/min; MCKhLPL Ra = 2.37 +/- 0.27 micromol/min). However, FFA turnover was significantly decreased after the 16-hour fast in MCKhLPL mice vs controls (Con Ra = 2.89 +/- 0.52 micromol/min; MCKhLPL Ra = 1.64 +/- 0.17 micromol/min; P < .05). The significantly lower FFA Ra in MCKhLPL vs control mice was due to a decrease in MCKhLPL FFA turnover from the 4- to 16-hour fast, whereas FFA turnover was unchanged in controls. The changes in FFA appearance after the 16-hour fast in MCKhLPL mice are most likely explained by increased reliance by skeletal muscle on plasma triglyceride as a fuel. These data suggest increased skeletal muscle LPL expression decreases dependence on plasma FFA during prolonged fasting in mice.
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Affiliation(s)
- Bryan C Bergman
- University of Colorado Health Sciences Center at Fitzsimons, Aurora, CO 80045, USA.
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