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Huynh MT, Erfani Z, Kovács Z, Park JM. Hyperpolarized [2- 13C, 3- 2H 3]Pyruvate Detects Hepatic Gluconeogenesis In Vivo. ACS Sens 2024; 9:2801-2805. [PMID: 38838349 PMCID: PMC11227886 DOI: 10.1021/acssensors.4c00734] [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] [Indexed: 06/07/2024]
Abstract
The feasibility of hyperpolarized [2-13C, 3-2H3]pyruvate for probing gluconeogenesis in vivo was investigated in this study. Whereas hyperpolarized [1-13C]pyruvate has clear access to metabolic pathways that convert pyruvate to lactate, alanine, and bicarbonate, its utility for assessing pyruvate carboxylation and gluconeogenesis has been limited by technical challenges, including spectral overlap and an obscure enzymatic step that decarboxylates the labeled carbon. To achieve unambiguous detection of gluconeogenic products, the carbonyl carbon in pyruvate was labeled with 13C. To prolong the T1 relaxation time, [2-13C, 3-2H3]pyruvate was synthesized and dissolved with D2O after dynamic nuclear polarization. The T1 of [2-13C, 3-2H3]pyruvate in D2O could be improved by 76.9% (79.6 s at 1 T and 74.5 s at 3 T) as compared to [2-13C]pyruvate in water. Hyperpolarized [2-13C, 3-2H3]pyruvate with D2O dissolution was applied to rat livers in vivo under normal feeding and fasting conditions. A gluconeogenic product, [2-13C]phosphoenolpyruvate, was observed at 149.9 ppm from fasted rats only, highlighting the utility of [2-13C, 3-2H3]pyruvate in detecting key gluconeogenic enzyme activities such as pyruvate carboxylase and phosphoenolpyruvate carboxykinase in vivo.
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Affiliation(s)
- Mai T Huynh
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | - Zohreh Erfani
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | - Zoltán Kovács
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | - Jae Mo Park
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
- Department of Biomedical Engineering, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
- Department of Radiology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
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2
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Coelho M, Mahar R, Belew GD, Torres A, Barosa C, Cabral F, Viegas I, Gastaldelli A, Mendes VM, Manadas B, Jones JG, Merritt ME. Enrichment of hepatic glycogen and plasma glucose from H₂ 18 O informs gluconeogenic and indirect pathway fluxes in naturally feeding mice. NMR IN BIOMEDICINE 2023; 36:e4837. [PMID: 36151589 PMCID: PMC9845176 DOI: 10.1002/nbm.4837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/22/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
Deuterated water (2 H2 O) is a widely used tracer of carbohydrate biosynthesis in both preclinical and clinical settings, but the significant kinetic isotope effects (KIE) of 2 H can distort metabolic information and mediate toxicity. 18 O-water (H2 18 O) has no significant KIE and is incorporated into specific carbohydrate oxygens via well-defined mechanisms, but to date it has not been evaluated in any animal model. Mice were given H2 18 O during overnight feeding and 18 O-enrichments of liver glycogen, triglyceride glycerol (TG), and blood glucose were quantified by 13 C NMR and mass spectrometry (MS). Enrichment of oxygens 5 and 6 relative to body water informed indirect pathway contributions from the Krebs cycle and triose phosphate sources. Compared with mice fed normal chow (NC), mice whose NC was supplemented with a fructose/glucose mix (i.e., a high sugar [HS] diet) had significantly higher indirect pathway contributions from triose phosphate sources, consistent with fructose glycogenesis. Blood glucose and liver TG 18 O-enrichments were quantified by MS. Blood glucose 18 O-enrichment was significantly higher for HS versus NC mice and was consistent with gluconeogenic fructose metabolism. TG 18 O-enrichment was extensive for both NC and HS mice, indicating a high turnover of liver triglyceride, independent of diet. Thus H2 18 O informs hepatic carbohydrate biosynthesis in similar detail to 2 H2 O but without KIE-associated risks.
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Affiliation(s)
- Margarida Coelho
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
- Department of Chemistry, Faculty of Sciences and TechnologyUniversity of CoimbraCoimbraPortugal
| | - Rohit Mahar
- Department of Biochemistry and Molecular BiologyUniversity of FloridaGainesvilleFloridaUSA
| | - Getachew D. Belew
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Alejandra Torres
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Cristina Barosa
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Fernando Cabral
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Ivan Viegas
- Center for Functional Ecology, Department of Life SciencesUniversity of CoimbraCoimbraPortugal
| | | | - Vera M. Mendes
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Bruno Manadas
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - John G. Jones
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular BiologyUniversity of FloridaGainesvilleFloridaUSA
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Magnetic Resonance Imaging and Spectroscopy Methods to Study Hepatic Glucose Metabolism and Their Applications in the Healthy and Diabetic Liver. Metabolites 2022; 12:metabo12121223. [PMID: 36557261 PMCID: PMC9788351 DOI: 10.3390/metabo12121223] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022] Open
Abstract
The liver plays an important role in whole-body glucose homeostasis by taking up glucose from and releasing glucose into the blood circulation. In the postprandial state, excess glucose in the blood circulation is stored in hepatocytes as glycogen. In the postabsorptive state, the liver produces glucose by breaking down glycogen and from noncarbohydrate precursors such as lactate. In metabolic diseases such as diabetes, these processes are dysregulated, resulting in abnormal blood glucose levels. Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are noninvasive techniques that give unique insight into different aspects of glucose metabolism, such as glycogenesis, glycogenolysis, and gluconeogenesis, in the liver in vivo. Using these techniques, liver glucose metabolism has been studied in regard to a variety of interventions, such as fasting, meal intake, and exercise. Moreover, deviations from normal hepatic glucose metabolism have been investigated in both patients with type 1 and 2 diabetes, as well as the effects of antidiabetic medications. This review provides an overview of current MR techniques to measure hepatic glucose metabolism and the insights obtained by the application of these techniques in the healthy and diabetic liver.
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4
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Belfleur L, Sonavane M, Hernandez A, Gassman NR, Migaud ME. Solution Chemistry of Dihydroxyacetone and Synthesis of Monomeric Dihydroxyacetone. Chem Res Toxicol 2022; 35:616-625. [PMID: 35324152 PMCID: PMC9020455 DOI: 10.1021/acs.chemrestox.1c00403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Indexed: 11/30/2022]
Abstract
Dihydroxyacetone (DHA) is a major byproduct of e-cigarette combustion and is the active ingredient in sunless tanning products. Mounting evidence points to its damaging effects on cellular functions. While developing a simple synthetic route to monomeric [13C3]DHA for flux metabolic studies that compared DHA and glyceraldehyde (GA) metabolism, we uncovered that solid DHA ages upon storage and differences in the relative abundance of each of its isomer occur when reconstituted in an aqueous solution. While all three of the dimeric forms of DHA ultimately resolve to the ketone and hydrated forms of monomeric DHA once in water at room temperature, these species require hours rather than minutes to reach an equilibrium favoring the monomeric species. Consequently, when used in bolus or flux experiments, the relative abundance of each isomer and its effects at the time of application is dependent on the initial DHA isomeric composition and concentration, and time of equilibration in solution before use. Here, we make recommendations for the more consistent handling of DHA as we report conditions that ensure that DHA is present in its monomeric form while in solutions, conditions used in an isotopic tracing study that specifically compared monomeric DHA and GA metabolism in cells.
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Affiliation(s)
- Luxene Belfleur
- Department
of Pharmacology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama 36604, United States
| | - Manoj Sonavane
- Department
of Pharmacology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama 36604, United States
- Department
of Pharmacology and Toxicology, the University
of Alabama at Birmingham, 1720 2nd Avenue S, Birmingham, Alabama 35294, United
States
| | - Arlet Hernandez
- Department
of Pharmacology and Toxicology, the University
of Alabama at Birmingham, 1720 2nd Avenue S, Birmingham, Alabama 35294, United
States
| | - Natalie R. Gassman
- Department
of Pharmacology and Toxicology, the University
of Alabama at Birmingham, 1720 2nd Avenue S, Birmingham, Alabama 35294, United
States
| | - Marie E. Migaud
- Department
of Pharmacology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama 36604, United States
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Giacalone AG, Merritt ME, Ragavan M. Ex Vivo Hepatic Perfusion Through the Portal Vein in Mouse. J Vis Exp 2022:10.3791/63154. [PMID: 35343950 PMCID: PMC9258001 DOI: 10.3791/63154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Metabolic diseases such as diabetes, pre-diabetes, non-alcoholic fatty liver disease (NAFLD), and nonalcoholic steatohepatitis (NASH) are becoming increasingly common. Ex vivo liver perfusions allow for a comprehensive analysis of liver metabolism using nuclear magnetic resonance (NMR), in nutritional conditions that can be rigorously controlled. As in silico simulations remain a primarily theoretical means of assessing hormone actions and the effects of pharmaceutical intervention, the perfused liver remains one of the most valuable test beds for understanding hepatic metabolism. As these studies guide basic insights into hepatic physiology, results must be accurate and reproducible. The greatest factor in the reproducibility of ex vivo hepatic perfusion is the quality of surgery. Therefore, we have introduced an organized and streamlined method to perform ex vivo mouse liver perfusions in the context of in situ NMR experiments. We also describe a unique application and discuss common issues encountered in these studies. The overall purpose is to provide an uncomplicated guide to a technique we have refined over several years that we deem the golden standard for obtaining reproducible results in hepatic resections and perfusions in the context of in situ NMR experiments. The distance to the center of the field for the magnet as well as the inaccessibility of the tissue to intervention during the NMR experiment makes our methods novel.
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Affiliation(s)
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida
| | - Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, University of Florida;
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Ragavan M, McLeod MA, Rushin A, Merritt ME. Detecting de novo Hepatic Ketogenesis Using Hyperpolarized [2- 13C] Pyruvate. Front Physiol 2022; 13:832403. [PMID: 35197867 PMCID: PMC8859440 DOI: 10.3389/fphys.2022.832403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 01/14/2022] [Indexed: 11/28/2022] Open
Abstract
The role of ketones in metabolic health has progressed over the past two decades, moving from what was perceived as a simple byproduct of fatty acid oxidation to a central player in a multiplicity of disease states. Previous work with hyperpolarized (HP) 13C has shown that ketone production can be detected when using precursors that labeled acetyl-CoA at the C1 position, often in tissues that are not normally recognized as ketogenic. Here, we assay metabolism of HP [2-13C]pyruvate in the perfused mouse liver, a classic metabolic testbed where nutritional conditions can be precisely controlled. Livers perfused with long-chain fatty acids or the medium-chain fatty acid octanoate showed no evidence of ketogenesis in the 13C spectrum. In contrast, addition of dichloroacetate, a potent inhibitor of pyruvate dehydrogenase kinase, resulted in significant production of both acetoacetate and 3-hydroxybutyrate from the pyruvate precursor. This result indicates that ketones are readily produced from carbohydrates, but only in the case where pyruvate dehydrogenase activity is upregulated.
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Affiliation(s)
| | | | | | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, United States
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Frahm AB, Hill D, Katsikis S, Andreassen T, Ardenkjær-Larsen JH, Bathen TF, Moestue SA, Jensen PR, Lerche MH. Classification and biomarker identification of prostate tissue from TRAMP mice with hyperpolarized 13C-SIRA. Talanta 2021; 235:122812. [PMID: 34517669 DOI: 10.1016/j.talanta.2021.122812] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 08/14/2021] [Accepted: 08/16/2021] [Indexed: 12/16/2022]
Abstract
Hyperpolarized 13C isotope resolved spectroscopy boosts NMR signal intensity, which improves signal detection and allows metabolic fluxes to be analyzed. Such hyperpolarized flux data may offer new approaches to tissue classification and biomarker identification that could be translated in vivo. Here we used hyperpolarized stable isotope resolved analysis (SIRA) to measure metabolite specific 13C isotopic enrichments in the central carbon metabolism of mouse prostate. Prostate and tumor tissue samples were acquired from transgenic adenocarcinomas of the mouse prostate (TRAMP) mice. Before euthanasia, mice were injected with [U-13C]glucose intraperitoneally (i.p.). Polar metabolite extracts were prepared, and hyperpolarized 1D-13C NMR spectra were obtained from normal prostate (n = 19) and cancer tissue (n = 19) samples. Binary classification and feature analysis was performed to make a separation model and to investigate differences between samples originating from normal and cancerous prostate tissue, respectively. Hyperpolarized experiments were carried out according to a standardized protocol, which showed a high repeatability (CV = 15%) and an average linewidth in the 1D-13C NMR spectra of 2 ± 0.5 Hz. The resolution of the hyperpolarized 1D-13C spectra was high with little signal overlap in the carbonyl region and metabolite identification was easily accomplished. A discrimination with 95% success rate could be made between samples originating from TRAMP mice prostate and tumor tissue based on isotopomers from uniquely identified metabolites. Hyperpolarized 13C-SIRA allowed detailed metabolic information to be obtained from tissue specimens. The positional information of 13C isotopic enrichments lead to easily interpreted features responsible for high predictive classification of tissue types. This analytical approach has matured, and the robust experimental protocols currently available allow systematic tracking of metabolite flux ex vivo.
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Affiliation(s)
- Anne B Frahm
- Center for Hyperpolarization in Magnetic Resonance, Department of Health Technology, Ørsteds plads 349, 2800, Kongens Lyngby, Denmark
| | - Deborah Hill
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
| | - Sotirios Katsikis
- Center for Hyperpolarization in Magnetic Resonance, Department of Health Technology, Ørsteds plads 349, 2800, Kongens Lyngby, Denmark
| | - Trygve Andreassen
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jan Henrik Ardenkjær-Larsen
- Center for Hyperpolarization in Magnetic Resonance, Department of Health Technology, Ørsteds plads 349, 2800, Kongens Lyngby, Denmark
| | - Tone Frost Bathen
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
| | - Siver Andreas Moestue
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway; Department of Pharmacy, Nord University, Bodø, Norway
| | - Pernille Rose Jensen
- Center for Hyperpolarization in Magnetic Resonance, Department of Health Technology, Ørsteds plads 349, 2800, Kongens Lyngby, Denmark
| | - Mathilde Hauge Lerche
- Center for Hyperpolarization in Magnetic Resonance, Department of Health Technology, Ørsteds plads 349, 2800, Kongens Lyngby, Denmark.
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Non-Invasive Analysis of Human Liver Metabolism by Magnetic Resonance Spectroscopy. Metabolites 2021; 11:metabo11110751. [PMID: 34822409 PMCID: PMC8623827 DOI: 10.3390/metabo11110751] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/26/2021] [Accepted: 10/26/2021] [Indexed: 11/16/2022] Open
Abstract
The liver is a key node of whole-body nutrient and fuel metabolism and is also the principal site for detoxification of xenobiotic compounds. As such, hepatic metabolite concentrations and/or turnover rates inform on the status of both hepatic and systemic metabolic diseases as well as the disposition of medications. As a tool to better understand liver metabolism in these settings, in vivo magnetic resonance spectroscopy (MRS) offers a non-invasive means of monitoring hepatic metabolic activity in real time both by direct observation of concentrations and dynamics of specific metabolites as well as by observation of their enrichment by stable isotope tracers. This review summarizes the applications and advances in human liver metabolic studies by in vivo MRS over the past 35 years and discusses future directions and opportunities that will be opened by the development of ultra-high field MR systems and by hyperpolarized stable isotope tracers.
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