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Assessment of Oxidative Metabolism in Brown Fat Using PET Imaging
Objective: Although it has been believed that brown adipose tissue (BAT) depots disappear shortly after the perinatal period in humans, positron emission tomography (PET) imaging using the glucose analog (18)F-deoxy-d-glucose (FDG) has shown unequivocally the existence of functional BAT in humans, s...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Frontiers Research Foundation
2012
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3355936/ https://www.ncbi.nlm.nih.gov/pubmed/22649408 http://dx.doi.org/10.3389/fendo.2012.00015 |
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author | Muzik, Otto Mangner, Thomas J. Granneman, James G. |
author_facet | Muzik, Otto Mangner, Thomas J. Granneman, James G. |
author_sort | Muzik, Otto |
collection | PubMed |
description | Objective: Although it has been believed that brown adipose tissue (BAT) depots disappear shortly after the perinatal period in humans, positron emission tomography (PET) imaging using the glucose analog (18)F-deoxy-d-glucose (FDG) has shown unequivocally the existence of functional BAT in humans, suggesting that most humans have some functional BAT. The objective of this study was to determine, using dynamic oxygen-15 ((15)O) PET imaging, to what extent BAT thermogenesis is activated in adults during cold stress and to establish the relationship between BAT oxidative metabolism and FDG tracer uptake. Methods: Fourteen adult normal subjects (9F/5M, 30 ± 7 years) underwent triple oxygen scans (H(2)(15)O, C(15)O, (15)O(2)) as well as indirect calorimetric measurements at both rest and following exposure to mild cold (16°C). Subjects were divided into two groups (BAT+ and BAT−) based on the presence or absence of FDG tracer uptake (SUV > 2) in cervical–supraclavicular BAT. Blood flow and oxygen extraction fraction (OEF) was calculated from dynamic PET scans at the location of BAT, muscle, and white adipose tissue (WAT). The metabolic rate of oxygen (MRO(2)) in BAT was determined and used to calculate the contribution of activated BAT to daily energy expenditure (DEE). Results: The median mass of activated BAT in the BAT+ group (5F, age 31 ± 8) was 52.4 g (range 14–68 g) and was 1.7 g (range 0–6.3 g) in the BAT − group (5M/4F, age 29 ± 6). Corresponding SUV values were significantly higher in the BAT+ as compared to the BAT− group (7.4 ± 3.7 vs. 1.9 ± 0.9; p = 0.03). Blood flow values in BAT were significantly higher in the BAT+ group as compared to the BAT− group (13.1 ± 4.4 vs. 5.7 ± 1.1 ml/100 g/min, p = 0.03), but were similar in WAT (4.1 ± 1.6 vs. 4.2 ± 1.8 ml/100 g/min) and muscle (3.7 ± 0.8 vs. 3.3 ± 1.2 ml/100 g/min). Moreover, OEF in BAT was similar in the two groups (0.56 ± 0.18 in BAT+ vs. 0.46 ± 0.19 in BAT−, p = 0.39). Calculated MRO(2) values in BAT increased from 0.95 ± 0.74 to 1.62 ± 0.82 ml/100 g/min in the BAT+ group and were significantly higher than those determined in the BAT− group (0.43 ± 0.27 vs. 0.56 ± 0.24, p = 0.67). The DEE associated with BAT oxidative metabolism was highly variable in the BAT+ group, with an average of 5.5 ± 6.4 kcal/day (range 0.57–15.3 kcal/day). Conclusion: BAT thermogenesis in humans accounts for less than 20 kcal/day during moderate cold stress, even in subjects with relatively large BAT depots. Furthermore, due to the large differences in blood flow and glucose metabolic rates in BAT between humans and rodents, the application of rodent data to humans is problematic and needs careful evaluation. |
format | Online Article Text |
id | pubmed-3355936 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2012 |
publisher | Frontiers Research Foundation |
record_format | MEDLINE/PubMed |
spelling | pubmed-33559362012-05-30 Assessment of Oxidative Metabolism in Brown Fat Using PET Imaging Muzik, Otto Mangner, Thomas J. Granneman, James G. Front Endocrinol (Lausanne) Endocrinology Objective: Although it has been believed that brown adipose tissue (BAT) depots disappear shortly after the perinatal period in humans, positron emission tomography (PET) imaging using the glucose analog (18)F-deoxy-d-glucose (FDG) has shown unequivocally the existence of functional BAT in humans, suggesting that most humans have some functional BAT. The objective of this study was to determine, using dynamic oxygen-15 ((15)O) PET imaging, to what extent BAT thermogenesis is activated in adults during cold stress and to establish the relationship between BAT oxidative metabolism and FDG tracer uptake. Methods: Fourteen adult normal subjects (9F/5M, 30 ± 7 years) underwent triple oxygen scans (H(2)(15)O, C(15)O, (15)O(2)) as well as indirect calorimetric measurements at both rest and following exposure to mild cold (16°C). Subjects were divided into two groups (BAT+ and BAT−) based on the presence or absence of FDG tracer uptake (SUV > 2) in cervical–supraclavicular BAT. Blood flow and oxygen extraction fraction (OEF) was calculated from dynamic PET scans at the location of BAT, muscle, and white adipose tissue (WAT). The metabolic rate of oxygen (MRO(2)) in BAT was determined and used to calculate the contribution of activated BAT to daily energy expenditure (DEE). Results: The median mass of activated BAT in the BAT+ group (5F, age 31 ± 8) was 52.4 g (range 14–68 g) and was 1.7 g (range 0–6.3 g) in the BAT − group (5M/4F, age 29 ± 6). Corresponding SUV values were significantly higher in the BAT+ as compared to the BAT− group (7.4 ± 3.7 vs. 1.9 ± 0.9; p = 0.03). Blood flow values in BAT were significantly higher in the BAT+ group as compared to the BAT− group (13.1 ± 4.4 vs. 5.7 ± 1.1 ml/100 g/min, p = 0.03), but were similar in WAT (4.1 ± 1.6 vs. 4.2 ± 1.8 ml/100 g/min) and muscle (3.7 ± 0.8 vs. 3.3 ± 1.2 ml/100 g/min). Moreover, OEF in BAT was similar in the two groups (0.56 ± 0.18 in BAT+ vs. 0.46 ± 0.19 in BAT−, p = 0.39). Calculated MRO(2) values in BAT increased from 0.95 ± 0.74 to 1.62 ± 0.82 ml/100 g/min in the BAT+ group and were significantly higher than those determined in the BAT− group (0.43 ± 0.27 vs. 0.56 ± 0.24, p = 0.67). The DEE associated with BAT oxidative metabolism was highly variable in the BAT+ group, with an average of 5.5 ± 6.4 kcal/day (range 0.57–15.3 kcal/day). Conclusion: BAT thermogenesis in humans accounts for less than 20 kcal/day during moderate cold stress, even in subjects with relatively large BAT depots. Furthermore, due to the large differences in blood flow and glucose metabolic rates in BAT between humans and rodents, the application of rodent data to humans is problematic and needs careful evaluation. Frontiers Research Foundation 2012-02-08 /pmc/articles/PMC3355936/ /pubmed/22649408 http://dx.doi.org/10.3389/fendo.2012.00015 Text en Copyright © 2012 Muzik, Mangner and Granneman. http://www.frontiersin.org/licenseagreement This is an open-access article distributed under the terms of the Creative Commons Attribution Non Commercial License, which permits non-commercial use, distribution, and reproduction in other forums, provided the original authors and source are credited. |
spellingShingle | Endocrinology Muzik, Otto Mangner, Thomas J. Granneman, James G. Assessment of Oxidative Metabolism in Brown Fat Using PET Imaging |
title | Assessment of Oxidative Metabolism in Brown Fat Using PET Imaging |
title_full | Assessment of Oxidative Metabolism in Brown Fat Using PET Imaging |
title_fullStr | Assessment of Oxidative Metabolism in Brown Fat Using PET Imaging |
title_full_unstemmed | Assessment of Oxidative Metabolism in Brown Fat Using PET Imaging |
title_short | Assessment of Oxidative Metabolism in Brown Fat Using PET Imaging |
title_sort | assessment of oxidative metabolism in brown fat using pet imaging |
topic | Endocrinology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3355936/ https://www.ncbi.nlm.nih.gov/pubmed/22649408 http://dx.doi.org/10.3389/fendo.2012.00015 |
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