1
|
Morimoto A, Nakamura S, Koyano K, Nishisho S, Nakao Y, Arioka M, Inoue K, Inoue E, Nishioka K, Morita H, Konishi Y, Hirao K, Kusaka T. Continuous monitoring using thermography can capture the heat oscillations maintaining body temperature in neonates. Sci Rep 2024; 14:10449. [PMID: 38714775 PMCID: PMC11076520 DOI: 10.1038/s41598-024-60718-y] [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] [Received: 10/17/2023] [Accepted: 04/26/2024] [Indexed: 05/10/2024] Open
Abstract
The body temperature of infants at equilibrium with their surroundings is balanced between heat production from metabolism and the transfer of heat to the environment. Total heat production is related to body size, which is closely related to metabolic rate and oxygen consumption. Body temperature control is a crucial aspect of neonatal medicine but we have often struggled with temperature measures. Contactless infrared thermography (IRT) is useful for vulnerable neonates and may be able to assess their spontaneous thermal metabolism. The present study focused on heat oscillations and their cause. IRT was used to measure the skin temperature every 15 s of neonates in an incubator. We analyzed the thermal data of 27 neonates (32 measurements), calculated the average temperature within specified regions, and extracted two frequency components-Components A and B-using the Savitzky-Golay method. Furthermore, we derived an equation describing the cycle-named cycle T-for maintaining body temperature according to body weight. A positive correlation was observed between cycle T and Component B (median [IQR]: 368 [300-506] s). This study sheds light on the physiological thermoregulatory function of newborns and will lead to improved temperature management methods for newborns, particularly premature, low-birth-weight infants.
Collapse
Affiliation(s)
- Aya Morimoto
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | - Shinji Nakamura
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | - Kosuke Koyano
- Maternal Perinatal Center, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | - Sae Nishisho
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | - Yasuhiro Nakao
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | - Makoto Arioka
- Maternal Perinatal Center, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | - Kota Inoue
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | - Eri Inoue
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | - Katsufumi Nishioka
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | - Hirosuke Morita
- Maternal Perinatal Center, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | - Yukihiko Konishi
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kitagun, Japan
| | | | - Takashi Kusaka
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kitagun, Japan.
| |
Collapse
|
2
|
Ma L, Xiong L, Huang G. Effects of mirabegron on brown adipose tissue and metabolism in humans: A systematic review and meta-analysis. Eur J Clin Pharmacol 2024; 80:317-333. [PMID: 38159219 DOI: 10.1007/s00228-023-03614-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 12/20/2023] [Indexed: 01/03/2024]
Abstract
BACKGROUND Brown adipose tissue (BAT) has emerged as a potential therapeutic target for metabolic disorders due to its thermogenic and anti-obesity properties. β3-adrenergic receptor (β3-AR) agonists have also gained attention as potential agents for BAT activation and metabolic regulation. Mirabegron, a selective β3-AR-agonist used clinically for overactive bladder syndrome, has been explored for its utility in metabolic disorders. However, the controversy surrounding the ability of mirabegron to activate BAT to accelerate metabolism requires further investigation. The aim of this systematic review is to characterize comprehensively the impact of mirabegron on human BAT and its metabolism. METHODS We searched PubMed Central, Web of Science, Embase, and Cochrane Library databases for relevant papers published from the date of database inception to March 2023 for systematic reviews and meta-analyses. We extracted data on primary outcome indicators such as BAT volume, BAT activity, body temperature, and resting energy expenditure (REE), as well as secondary outcome indicators such as heart rate (HR), diastolic blood pressure (DBP), systolic blood pressure (SBP), non-esterified fatty acids (NEFA), blood glucose, and blood insulin from relevant studies. For studies that did not provide suitable data for meta-analysis, we used narrative data synthesis. For studies that provided suitable data for meta-analysis, we conducted meta-analysis using RevMan 5.4 software. RESULTS We reviewed 10 papers and included 6 in our meta-analysis. Our findings revealed no significant changes in BAT volume (p = 0.72) or blood glucose (p = 0.52) with mirabegron when compared to the placebo or pre-dose population. However, patients showed significant increases in BAT activity (p < 0.01), blood NEFA (p < 0.01), body temperature (p < 0.01), REE (p < 0.01), HR (p < 0.01), DBP (p < 0.01), SBP (p = 0.25), and blood insulin (p < 0.01). CONCLUSION Through our meta-analysis of 6 papers, we found that mirabegron has the potential to increase human BAT activity, REE, NEFA content, body temperature, HR, blood pressure, and blood insulin content. These effects may lead to reductions in blood glucose levels in obese/overweight and diabetic patients. Additionally, the activation of BAT by mirabegron could represent a novel approach for treating obesity, diabetes, and cardiovascular disease. TRIAL REGISTRATION NUMBER AND DATE CRD42023413446, 04/11/2023.
Collapse
Affiliation(s)
- Lili Ma
- First Clinical School of Medicine, Gansu University of Chinese Medicine, Lanzhou, China
| | - Lianqiu Xiong
- First Clinical School of Medicine, Gansu University of Chinese Medicine, Lanzhou, China
| | - Gang Huang
- Department of Radiology, Gansu Provincial Hospital, Lanzhou, China.
| |
Collapse
|
3
|
Holmes LR, Garside JC, Frank J, Livingston E, Snyder J, Abu Khalaf N, Yuan H, Branca RT. In-vivo detection of white adipose tissue browning: a multimodality imaging approach. Sci Rep 2023; 13:15485. [PMID: 37726379 PMCID: PMC10509182 DOI: 10.1038/s41598-023-42537-9] [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] [Received: 06/02/2023] [Accepted: 09/11/2023] [Indexed: 09/21/2023] Open
Abstract
Detection and differentiation of brown fat in humans poses several challenges, as this tissue is sparse and often mixed with white adipose tissue. Non-invasive detection of beige fat represents an even greater challenge as this tissue is structurally and functionally more like white fat than brown fat. Here we used positron emission tomography with 18F-fluorodeoxyglucose, computed tomography, xenon-enhanced computed tomography, and dynamic contrast-enhanced ultrasound, to non-invasively detect functional and structural changes associated with the browning process of inguinal white fat, induced in mice by chronic stimulation with the β3-adrenergic receptor agonist CL-316243. These studies reveal a very heterogeneous increase in baseline tissue radiodensity and xenon-enhanced radiodensity, indicative of both an increase in adipocytes water and protein content as well as tissue perfusion, mostly in regions that showed enhanced norepinephrine-stimulated perfusion before CL-316243 treatment. No statistically significant increase in 18F-fluorodeoxyglucose uptake or norepinephrine-stimulated tissue perfusion were observed in the mice after the CL-316243 treatment. The increase in tissue-water content and perfusion, along with the negligible increase in the tissue glucose uptake and norepinephrine-stimulated perfusion deserve more attention, especially considering the potential metabolic role that this tissue may play in whole body metabolism.
Collapse
Affiliation(s)
- Leah R Holmes
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - John C Garside
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Jonathan Frank
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Eric Livingston
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Jonas Snyder
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Nada Abu Khalaf
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Hong Yuan
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Rosa T Branca
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
| |
Collapse
|
4
|
Law JM, Morris DE, Robinson LJ, Symonds ME, Budge H. Semi-automated analysis of supraclavicular thermal images increases speed of brown adipose tissue analysis without increasing variation in results. Curr Res Physiol 2021; 4:177-182. [PMID: 34746836 PMCID: PMC8562194 DOI: 10.1016/j.crphys.2021.07.001] [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: 11/12/2020] [Revised: 04/22/2021] [Accepted: 07/07/2021] [Indexed: 12/03/2022] Open
Abstract
Interest in brown adipose tissue remains high a decade after it was determined to be present outside of the neonatal period. In vivo imaging, however, has remained a challenge due to the lack of a imaging modality suitable for large healthy-volunteer studies, post-prandial investigations and vulnerable groups, such as children. Infrared thermography is increasingly accepted as a valid, non-invasive and flexible alternative but there is a wide approach to analysis between different groups. Defining the region of interest with anatomical borders rather than using a simple polygon may have advantages in terms of consistency but makes image analysis slower, limiting some applications. Our novel semi-automated method, using a custom-built graphical user interface, allows an 86% improvement in speed of image analysis (54.9 (38.3–71.4) seconds/image) without increases in variation between analysers or with repeated analysis. The improved efficiency demonstrated makes feasible larger studies, longer imaging periods or increased image acquisition frequency, providing an opportunity to study novel features of brown adipose tissue function. Brown adipose tissue is a key heat-generating tissue but is difficult to measure. Thermal imaging can measure brown adipose tissue response without radiation. A semi-automated approach increases image analysis efficiency. Thermal video analysis and imaging over longer periods is now feasible.
Collapse
Affiliation(s)
- James M Law
- Early Life Research Unit, Division of Child Health, Obstetrics & Gynaecology, University of Nottingham, United Kingdom
| | - David E Morris
- Bioengineering Research Group, Faculty of Engineering, University of Nottingham, United Kingdom
| | - Lindsay J Robinson
- Early Life Research Unit, Division of Child Health, Obstetrics & Gynaecology, University of Nottingham, United Kingdom
| | - Michael E Symonds
- Early Life Research Unit, Division of Child Health, Obstetrics & Gynaecology, University of Nottingham, United Kingdom.,Nottingham Digestive Disease Centre and Biomedical Research Centre, School of Medicine, University of Nottingham, NG7 2UH, United Kingdom
| | - Helen Budge
- Early Life Research Unit, Division of Child Health, Obstetrics & Gynaecology, University of Nottingham, United Kingdom
| |
Collapse
|
5
|
Yang J, Zhang H, Parhat K, Xu H, Li M, Wang X, Ran C. Molecular Imaging of Brown Adipose Tissue Mass. Int J Mol Sci 2021; 22:ijms22179436. [PMID: 34502347 PMCID: PMC8431742 DOI: 10.3390/ijms22179436] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 12/28/2022] Open
Abstract
Brown adipose tissue (BAT), a uniquely thermogenic tissue that plays an important role in metabolism and energy expenditure, has recently become a revived target in the fight against metabolic diseases, such as obesity, diabetes, and non-alcoholic fatty liver disease (NAFLD). Different from white adipose tissue (WAT), the brown adipocytes have distinctive features including multilocular lipid droplets, a large number of mitochondria, and a high expression of uncoupling protein-1 (UCP-1), as well as abundant capillarity. These histologic characteristics provide an opportunity to differentiate BAT from WAT using imaging modalities, such as PET/CT, SPECT/CT, MRI, NIRF and Ultrasound. However, most of the reported imaging methods were BAT activation dependent, and the imaging signals could be affected by many factors, including environmental temperatures and the states of the sympathetic nervous system. Accurate BAT mass detection methods that are independent of temperature and hormone levels have the capacity to track the development and changes of BAT throughout the lifetime of mammals, and such methods could be very useful for the investigation of potential BAT-related therapies. In this review, we focus on molecular imaging modalities that can detect and quantify BAT mass. In addition, their detection mechanism and limitations will be discussed as well.
Collapse
Affiliation(s)
- Jing Yang
- School of Engineering, China Pharmaceutical University, Nanjing 210009, China; (H.Z.); (K.P.); (H.X.); (M.L.); (X.W.)
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Room 2301, Building 149, Charlestown, Boston, MA 02129, USA
- Correspondence: (J.Y.); (C.R.)
| | - Haili Zhang
- School of Engineering, China Pharmaceutical University, Nanjing 210009, China; (H.Z.); (K.P.); (H.X.); (M.L.); (X.W.)
| | - Kadirya Parhat
- School of Engineering, China Pharmaceutical University, Nanjing 210009, China; (H.Z.); (K.P.); (H.X.); (M.L.); (X.W.)
| | - Hui Xu
- School of Engineering, China Pharmaceutical University, Nanjing 210009, China; (H.Z.); (K.P.); (H.X.); (M.L.); (X.W.)
| | - Mingshuang Li
- School of Engineering, China Pharmaceutical University, Nanjing 210009, China; (H.Z.); (K.P.); (H.X.); (M.L.); (X.W.)
| | - Xiangyu Wang
- School of Engineering, China Pharmaceutical University, Nanjing 210009, China; (H.Z.); (K.P.); (H.X.); (M.L.); (X.W.)
| | - Chongzhao Ran
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Room 2301, Building 149, Charlestown, Boston, MA 02129, USA
- Correspondence: (J.Y.); (C.R.)
| |
Collapse
|
6
|
Pérez DIV, Soto DAS, Barroso JM, Dos Santos DA, Queiroz ACC, Miarka B, Brito CJ, Quintana MS. Physically active men with high brown adipose tissue activity showed increased energy expenditure after caffeine supplementation. J Therm Biol 2021; 99:103000. [PMID: 34420632 DOI: 10.1016/j.jtherbio.2021.103000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/10/2021] [Accepted: 05/16/2021] [Indexed: 01/15/2023]
Abstract
This study measured the effect of caffeine on brown adipose tissue (BAT) activity and the energy expenditure (EE) of subjects with high (HBAT) or low (LBAT) activation. We performed a quasi-experimental double-blind protocol in which 24 physically active healthy men were measured (age: 24.1 ± 6.0 yrs; BM: 75.3 ± 14.4 kg; HT: 171.8 ± 5.9 cm; BMI: 25.5 ± 4.9 kg/m2). Infrared thermography (IRT) protocol was used to separate the participants into the groups according to the BAT activation: high (HBAT; n = 11) and low (LBAT; n = 13). All participants ingested a single supplement caffeine capsule (CAF) of 375 mg (~5 mg/kg BM) or placebo (PLA). Our experimental protocol measured two groups (HBAT and LBAT) under two conditions (CAF and PLA), with intake 30-min before the data collection. BAT activity lasted 60-min (0, 10, 20, 30, 40, 50, 60 min) and was estimated by IRT in subclavicular (Δ SCV) and external (Δ EXT) regions of interest (ROI) and EE by indirect calorimetry. The main results indicated that HBAT at 40-min showed an increased EE versus the other groups and conditions (p = 0.009). There was a significant difference for BAT activation at the 30 (p = 0.019), 40 (p = 0.009), 50 (p = 0.007) and 60 min (p = 0.012) between HBAT-CAF vs. LBAT-CAF. There was also a significant difference at the 20 (p = 0.024), 30 (p = 0.036), 50 (p = 0.05) and 60 min (p = 0.011) between HBAT-CAF vs. HBAT-PLA. In conclusion CAF intake (≈5 mg) increases the thermogenic activity of BAT in healthy young men and increases EE in HBAT subjects.
Collapse
Affiliation(s)
- Diego Ignacio Valenzuela Pérez
- Escuela de Kinesiología, Facultad de Salud, Universidad Santo Tomás, Santiago, Chile; Magister en Ciencias la Actividad Física y Deportes Aplicadas al Entrenamiento Rehabilitación y Reintegro Deportivo, Universidad Santo Tomás, Santiago, Chile; Facultad de Ciencias de la Actividad Física y del Deporte (INEF), Universidad Politécnica de Madrid, Madrid, Spain
| | - Dany Alexis Sobarzo Soto
- Escuela de Kinesiología, Facultad de Salud, Universidad Santo Tomás, Santiago, Chile; Magister en Ciencias la Actividad Física y Deportes Aplicadas al Entrenamiento Rehabilitación y Reintegro Deportivo, Universidad Santo Tomás, Santiago, Chile
| | - Julieta Montañez Barroso
- Magister en Ciencias la Actividad Física y Deportes Aplicadas al Entrenamiento Rehabilitación y Reintegro Deportivo, Universidad Santo Tomás, Santiago, Chile
| | - Diego Alves Dos Santos
- Physical Education Department, Federal University of Juiz de Fora, Governador Valadares, MG, Brazil
| | | | - Bianca Miarka
- Laboratory of Psychophysiology and Performance in Sports & Combats, School of Physical Education and Sport, Federal University of Rio De Janeiro, Rio De Janeiro, Brazil
| | - Ciro José Brito
- Physical Education Department, Federal University of Juiz de Fora, Governador Valadares, MG, Brazil.
| | - Manuel Sillero Quintana
- Facultad de Ciencias de la Actividad Física y del Deporte (INEF), Universidad Politécnica de Madrid, Madrid, Spain
| |
Collapse
|
7
|
Liao J, Yang L. Optical whispering-gallery mode barcodes for high-precision and wide-range temperature measurements. LIGHT, SCIENCE & APPLICATIONS 2021; 10:32. [PMID: 33547272 PMCID: PMC7862871 DOI: 10.1038/s41377-021-00472-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 11/20/2020] [Accepted: 01/12/2021] [Indexed: 05/11/2023]
Abstract
Temperature is one of the most fundamental physical properties to characterize various physical, chemical, and biological processes. Even a slight change in temperature could have an impact on the status or dynamics of a system. Thus, there is a great need for high-precision and large-dynamic-range temperature measurements. Conventional temperature sensors encounter difficulties in high-precision thermal sensing on the submicron scale. Recently, optical whispering-gallery mode (WGM) sensors have shown promise for many sensing applications, such as thermal sensing, magnetic detection, and biosensing. However, despite their superior sensitivity, the conventional sensing method for WGM resonators relies on tracking the changes in a single mode, which limits the dynamic range constrained by the laser source that has to be fine-tuned in a timely manner to follow the selected mode during the measurement. Moreover, we cannot derive the actual temperature from the spectrum directly but rather derive a relative temperature change. Here, we demonstrate an optical WGM barcode technique involving simultaneous monitoring of the patterns of multiple modes that can provide a direct temperature readout from the spectrum. The measurement relies on the patterns of multiple modes in the WGM spectrum instead of the changes of a particular mode. It can provide us with more information than the single-mode spectrum, such as the precise measurement of actual temperatures. Leveraging the high sensitivity of WGMs and eliminating the need to monitor particular modes, this work lays the foundation for developing a high-performance temperature sensor with not only superior sensitivity but also a broad dynamic range.
Collapse
Affiliation(s)
- Jie Liao
- Department of Electrical & Systems Engineering, Washington University in St. Louis, MO 63130, St. Louis, USA
| | - Lan Yang
- Department of Electrical & Systems Engineering, Washington University in St. Louis, MO 63130, St. Louis, USA.
- Department of Physics, Washington University in St. Louis, MO 63130, St. Louis, USA.
| |
Collapse
|
8
|
Functional characterization of human brown adipose tissue metabolism. Biochem J 2020; 477:1261-1286. [PMID: 32271883 DOI: 10.1042/bcj20190464] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/13/2020] [Accepted: 03/16/2020] [Indexed: 02/07/2023]
Abstract
Brown adipose tissue (BAT) has long been described according to its histological features as a multilocular, lipid-containing tissue, light brown in color, that is also responsive to the cold and found especially in hibernating mammals and human infants. Its presence in both hibernators and human infants, combined with its function as a heat-generating organ, raised many questions about its role in humans. Early characterizations of the tissue in humans focused on its progressive atrophy with age and its apparent importance for cold-exposed workers. However, the use of positron emission tomography (PET) with the glucose tracer [18F]fluorodeoxyglucose ([18F]FDG) made it possible to begin characterizing the possible function of BAT in adult humans, and whether it could play a role in the prevention or treatment of obesity and type 2 diabetes (T2D). This review focuses on the in vivo functional characterization of human BAT, the methodological approaches applied to examine these features and addresses critical gaps that remain in moving the field forward. Specifically, we describe the anatomical and biomolecular features of human BAT, the modalities and applications of non-invasive tools such as PET and magnetic resonance imaging coupled with spectroscopy (MRI/MRS) to study BAT morphology and function in vivo, and finally describe the functional characteristics of human BAT that have only been possible through the development and application of such tools.
Collapse
|
9
|
Brasil S, Renck AC, de Meneck F, Brioschi ML, Costa EF, Teixeira MJ. A systematic review on the role of infrared thermography in the Brown adipose tissue assessment. Rev Endocr Metab Disord 2020; 21:37-44. [PMID: 31965434 DOI: 10.1007/s11154-020-09539-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Brown adipose tissue (BAT) is an endocrine adipose tissue with attributes to dissipate energy as heat in response to changes in temperature and diet. Infrared thermography (IRT) has been studied in recent years in the assessment of BAT thermogenesis, as an option to positron emission tomography - computed tomography (PET-CT), because of several advantages. We performed a systematic review on the use of IRT in BAT assessment. Comprehensive online search was performed in different databases. The QUADAS 2 tool was used to evaluate studies' quality. 12 studies fit the inclusion criteria, whereas only one of these was considered of low risk of bias. 10 studies were favorable to IRT appliance in BAT evaluation, observing elevation of supraclavicular skin temperature correlated with BAT activity. Studies were heterogeneous in design, and a meta-analysis was precluded. Further studies with similar methodologies are needed. Conclusion: Despite the large number of published methodologies, IRT is a promising method for detecting BAT activation. Current knowledge already allows a better understanding of thermography to improve and standardize the technique.
Collapse
Affiliation(s)
- Sérgio Brasil
- Division of Neurological Surgery. Hospital das Clínicas, School of Medicine, University of São Paulo, São Paulo, Brazil.
| | - Alessandra C Renck
- Department of Endocrinology, School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Franciele de Meneck
- Department of Nephrology, School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - Marcos L Brioschi
- Division of Neurological Surgery. Hospital das Clínicas, School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Elaine F Costa
- Department of Endocrinology, School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Manoel J Teixeira
- Division of Neurological Surgery. Hospital das Clínicas, School of Medicine, University of São Paulo, São Paulo, Brazil
| |
Collapse
|
10
|
Sun L, Yan J, Goh HJ, Govindharajulu P, Verma S, Michael N, Sadananthan SA, Henry CJ, Velan SS, Leow MKS. Fibroblast Growth Factor-21, Leptin, and Adiponectin Responses to Acute Cold-Induced Brown Adipose Tissue Activation. J Clin Endocrinol Metab 2020; 105:5698244. [PMID: 31912874 PMCID: PMC7015460 DOI: 10.1210/clinem/dgaa005] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/07/2020] [Indexed: 01/01/2023]
Abstract
BACKGROUND Adipocyte-derived hormones play a role in insulin sensitivity and energy homeostasis. However, the relationship between circulating fibroblast growth factor 21 (FGF21), adipocytokines and cold-induced supraclavicular brown adipose tissue (sBAT) activation is underexplored. OBJECTIVE Our study aimed to investigate the relationships between cold-induced sBAT activity and plasma FGF21 and adipocytokines levels in healthy adults. DESIGN Nineteen healthy participants underwent energy expenditure (EE) and supraclavicular infrared thermography (IRT) within a whole-body calorimeter at baseline and at 2 hours post-cold exposure. 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography/magnetic resonance (PET/MR) imaging scans were performed post-cold exposure. PET sBAT mean standardized uptake value (SUV mean), MR supraclavicular fat fraction (sFF), anterior supraclavicular maximum temperature (Tscv max) and EE change (%) after cold exposure were used to quantify sBAT activity. MAIN OUTCOME MEASURES Plasma FGF21, leptin, adiponectin, and tumor necrosis factor alpha (TNFα) at baseline and 2 hours post-cold exposure. Body composition at baseline by dual-energy x-ray absorptiometry (DXA). RESULTS Plasma FGF21 and adiponectin levels were significantly reduced after cold exposure in BAT-positive subjects but not in BAT-negative subjects. Leptin concentration was significantly reduced in both BAT-positive and BAT-negative participants after cold exposure. Adiponectin concentration at baseline was positively strongly associated with sBAT PET SUV mean (coefficient, 3269; P = 0.01) and IRT Tscv max (coefficient, 6801; P = 0.03), and inversely correlated with MR sFF (coefficient, -404; P = 0.02) after cold exposure in BAT-positive subjects but not in BAT-negative subjects. CONCLUSION Higher adiponectin concentrations at baseline indicate a greater cold-induced sBAT activity, which may be a novel predictor for sBAT activity in healthy BAT-positive adults. HIGHLIGHTS A higher adiponectin concentration at baseline was associated with higher cold-induced supraclavicular BAT PET SUV mean and IRT Tscv max, and lower MR supraclavicular FF. Adiponectin levels maybe a novel predictor for cold-induced sBAT activity.
Collapse
Affiliation(s)
- Lijuan Sun
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR) and National University Health System (NUHS), Singapore
| | - Jianhua Yan
- Shanghai Key Laboratory for Molecular Imaging, Shanghai University of Medicine and Health Sciences, Shanghai, China
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
- Molecular Imaging Precision Medicine Collaborative Innovation Centre, Shanxi Medical University, Taiyuan, China
| | - Hui Jen Goh
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR) and National University Health System (NUHS), Singapore
| | - Priya Govindharajulu
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR) and National University Health System (NUHS), Singapore
| | - Sanjay Verma
- Laboratory of Molecular Imaging, Singapore Bioimaging Consortium, Agency for Science Technology and Research (A*STAR), Singapore
| | - Navin Michael
- Singapore Institute of Clinical Sciences, Agency for Science Technology and Research (A*STAR), Singapore
| | - Suresh Anand Sadananthan
- Singapore Institute of Clinical Sciences, Agency for Science Technology and Research (A*STAR), Singapore
| | - Christiani Jeyakumar Henry
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR) and National University Health System (NUHS), Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore
| | - S Sendhil Velan
- Laboratory of Molecular Imaging, Singapore Bioimaging Consortium, Agency for Science Technology and Research (A*STAR), Singapore
- Singapore Institute of Clinical Sciences, Agency for Science Technology and Research (A*STAR), Singapore
- Departments of Physiology & Medicine, National University of Singapore (NUS), Singapore
| | - Melvin Khee-Shing Leow
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR) and National University Health System (NUHS), Singapore
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University (NTU), Singapore
- Department of Endocrinology, Tan Tock Seng Hospital (TTSH), Singapore
- Correspondence and Reprint Requests: Melvin Khee-Shing Leow, MD, PhD, FACP, FACE (USA), FRCP (Edin), FRCPath, Centre for Translational Medicine, 14 Medical Drive #07-02, MD 6 Building, Yong Loo Lin School of Medicine, Singapore, Singapore 117599.
| |
Collapse
|
11
|
Tay SH, Goh HJ, Govindharajulu P, Cheng J, Camps SG, Haldar S, Velan SS, Sun L, Li Y, Henry CJ, Leow MKS. Brown fat activity determined by infrared thermography and thermogenesis measurement using whole body calorimetry (BRIGHT Study). Physiol Res 2020; 69:85-97. [PMID: 31852199 DOI: 10.33549/physiolres.934190] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
To assess BAT activity in humans at a population level, infrared thermography (IRT) represents a safe, readily repeatable and affordable alternative to 18F-FDG-PET. Building upon a previously proposed method by our laboratory, we further refined the image computational algorithm to quantify BAT activation in the cervical-supraclavicular (C-SCV) region of healthy young men under thermo-neutral and cold exposure conditions. Additionally, we validated the whole-body calorimeter (WBC) in reliably measuring cold-induced thermogenesis. The temperature gradient between C-SCV-deltoid regions, and the corresponding difference in heat power output, increased upon cold air exposure relative to thermo-neutral conditions (by 74.88 %, p<0.0001; and by 71.34 %, p<0.0001 respectively). Resting and cumulative energy expenditure (EE) rose significantly (by 13.14 % and 9.12 % respectively, p=0.0001) while positive correlations between IRT measures and EE were found with cold air exposure (percentage change in heat power gradient between ROI and deltoid, cold air: r(2)=0.29, p=0.026, Pearson's correlation). IRT and WBC can be used to study BAT activation. The refined algorithm allows for more automation and objectivity in IRT data analysis, especially under cold air exposures.
Collapse
Affiliation(s)
- S H Tay
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Jimenez‐Pavon D, Corral‐Perez J, Sánchez‐Infantes D, Villarroya F, Ruiz JR, Martinez‐Tellez B. Infrared Thermography for Estimating Supraclavicular Skin Temperature and BAT Activity in Humans: A Systematic Review. Obesity (Silver Spring) 2019; 27:1932-1949. [PMID: 31691547 PMCID: PMC6899990 DOI: 10.1002/oby.22635] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 07/25/2019] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Brown adipose tissue (BAT) is a thermogenic tissue with potential as a therapeutic target in the treatment of obesity and related metabolic disorders. The most used technique for quantifying human BAT activity is the measurement of 18 F-fluorodeoxyglucose uptake via a positron emission tomography/computed tomography scan following exposure to cold. However, several studies have indicated the measurement of the supraclavicular skin temperature (SST) by infrared thermography (IRT) to be a less invasive alternative. This work reviews the state of the art of this latter method as a means of determining BAT activity in humans. METHODS The data sources for this review were PubMed, Web of Science, and EBSCOhost (SPORTdiscus), and eligible studies were those conducted in humans. RESULTS In most studies in which participants were first cooled, an increase in IRT-measured SST was noted. However, only 5 of 24 such studies also involved a nuclear technique that confirmed increased activity in BAT, and only 2 took into account the thickness of the fat layer when measuring SST by IRT. CONCLUSIONS More work is needed to understand the involvement of tissues other than BAT in determining IRT-measured SST; at present, IRT cannot determine whether any increase in SST is due to increased BAT activity.
Collapse
Affiliation(s)
- David Jimenez‐Pavon
- MOVE‐IT Research Group, Department of Physical Education, Faculty of Education SciencesUniversity of CádizCádizSpain
- Biomedical Research and Innovation Institute of Cádiz (INiBICA) Research Unit, Puerta del Mar University Hospital, University of CádizCádizSpain
| | - Juan Corral‐Perez
- MOVE‐IT Research Group, Department of Physical Education, Faculty of Education SciencesUniversity of CádizCádizSpain
- Biomedical Research and Innovation Institute of Cádiz (INiBICA) Research Unit, Puerta del Mar University Hospital, University of CádizCádizSpain
| | - David Sánchez‐Infantes
- Department of Endocrinology and NutritionGermans Trias i Pujol Research InstituteBadalonaBarcelonaSpain
- Biomedical Research Center (Fisiopatología de la Obesidad y Nutrición) (CIBEROBN), ISCIIIMadridSpain
| | - Francesc Villarroya
- Biomedical Research Center (Fisiopatología de la Obesidad y Nutrición) (CIBEROBN), ISCIIIMadridSpain
- Department of Biochemistry and Molecular BiomedicineInstitute of BiomedicineBarcelonaSpain
| | - Jonatan R. Ruiz
- PROFITH (PROmoting FITness and Health through Physical Activity) Research Group, Department of Physical Education and Sports, Faculty of Sport SciencesSport and Health University Research Institute (iMUDS), University of GranadaGranadaSpain
| | - Borja Martinez‐Tellez
- PROFITH (PROmoting FITness and Health through Physical Activity) Research Group, Department of Physical Education and Sports, Faculty of Sport SciencesSport and Health University Research Institute (iMUDS), University of GranadaGranadaSpain
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CentreLeidenthe Netherlands
| |
Collapse
|
13
|
Antonacci MA, McHugh C, Kelley M, McCallister A, Degan S, Branca RT. Direct detection of brown adipose tissue thermogenesis in UCP1-/- mice by hyperpolarized 129Xe MR thermometry. Sci Rep 2019; 9:14865. [PMID: 31619741 PMCID: PMC6795875 DOI: 10.1038/s41598-019-51483-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 10/02/2019] [Indexed: 12/19/2022] Open
Abstract
Brown adipose tissue (BAT) is a type of fat specialized in non-shivering thermogenesis. While non-shivering thermogenesis is mediated primarily by uncoupling protein 1 (UCP1), the development of the UCP1 knockout mouse has enabled the study of possible UCP1-independent non-shivering thermogenic mechanisms, whose existence has been shown so far only indirectly in white adipose tissue and still continues to be a matter of debate in BAT. In this study, by using magnetic resonance thermometry with hyperpolarized xenon, we produce the first direct evidence of UCP1-independent BAT thermogenesis in knockout mice. We found that, following adrenergic stimulation, the BAT temperature of knockout mice increases more and faster than rectal temperature. While with this study we cannot exclude or separate the physiological effect of norepinephrine on core body temperature, the fast increase of iBAT temperature seems to suggest the existence of a possible UCP1-independent thermogenic mechanism responsible for this temperature increase.
Collapse
Affiliation(s)
- Michael A Antonacci
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Physics, Saint Vincent College, Latrobe, Pennsylvania, United States of America
| | - Christian McHugh
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Michele Kelley
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Andrew McCallister
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Simone Degan
- Department of Radiology, Duke University, Durham, North Carolina, United States of America
| | - Rosa T Branca
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
| |
Collapse
|
14
|
Oreskovich SM, Ong FJ, Ahmed BA, Konyer NB, Blondin DP, Gunn E, Singh NP, Noseworthy MD, Haman F, Carpentier AC, Punthakee Z, Steinberg GR, Morrison KM. MRI Reveals Human Brown Adipose Tissue Is Rapidly Activated in Response to Cold. J Endocr Soc 2019; 3:2374-2384. [PMID: 31745532 PMCID: PMC6855213 DOI: 10.1210/js.2019-00309] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/08/2019] [Indexed: 01/05/2023] Open
Abstract
Context In rodents, cold exposure induces the activation of brown adipose tissue (BAT) and the induction of intracellular triacylglycerol (TAG) lipolysis. However, in humans, the kinetics of supraclavicular (SCV) BAT activation and the potential importance of TAG stores remain poorly defined. Objective To determine the time course of BAT activation and changes in intracellular TAG using MRI assessment of the SCV (i.e., BAT depot) and fat in the posterior neck region (i.e., non-BAT). Design Cross-sectional. Setting Clinical research center. Patients or Other Participants Twelve healthy male volunteers aged 18 to 29 years [body mass index = 24.7 ± 2.8 kg/m2 and body fat percentage = 25.0% ± 7.4% (both, mean ± SD)]. Intervention(s) Standardized whole-body cold exposure (180 minutes at 18°C) and immediate rewarming (30 minutes at 32°C). Main Outcome Measure(s) Proton density fat fraction (PDFF) and T2* of the SCV and posterior neck fat pads. Acquisitions occurred at 5- to 15-minute intervals during cooling and subsequent warming. Results SCV PDFF declined significantly after only 10 minutes of cold exposure [−1.6% (SE: 0.44%; P = 0.007)] and continued to decline until 35 minutes, after which time it remained stable until 180 minutes. A similar time course was also observed for SCV T2*. In the posterior neck fat (non-BAT), there were no cold-induced changes in PDFF or T2*. Rewarming did not result in a change in SCV PDFF or T2*. Conclusions The rapid cold-induced decline in SCV PDFF suggests that in humans BAT is activated quickly in response to cold and that TAG is a primary substrate.
Collapse
Affiliation(s)
- Stephan M Oreskovich
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada.,Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada
| | - Frank J Ong
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| | - Basma A Ahmed
- Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Norman B Konyer
- Imaging Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada
| | - Denis P Blondin
- Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Elizabeth Gunn
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada.,Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada
| | - Nina P Singh
- Department of Radiology, McMaster University Medical Center, Hamilton, Ontario, Canada
| | - Michael D Noseworthy
- Imaging Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada.,Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada.,McMaster School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada
| | - Francois Haman
- School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Andre C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Zubin Punthakee
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada.,Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada.,Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Gregory R Steinberg
- Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.,Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Katherine M Morrison
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada.,Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada
| |
Collapse
|
15
|
Moonen MP, Nascimento EB, van Marken Lichtenbelt WD. Human brown adipose tissue: Underestimated target in metabolic disease? Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:104-112. [DOI: 10.1016/j.bbalip.2018.05.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 03/16/2018] [Accepted: 05/21/2018] [Indexed: 02/06/2023]
|
16
|
Recent advances in the detection of brown adipose tissue in adult humans: a review. Clin Sci (Lond) 2018; 132:1039-1054. [PMID: 29802209 DOI: 10.1042/cs20170276] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 03/23/2018] [Accepted: 03/23/2018] [Indexed: 02/07/2023]
Abstract
The activation of brown adipose tissue (BAT) is associated with reductions in circulating lipids and glucose in rodents and contributes to energy expenditure in humans indicating the potential therapeutic importance of targetting this tissue for the treatment of a variety of metabolic disorders. In order to evaluate the therapeutic potential of human BAT, a variety of methodologies for assessing the volume and metabolic activity of BAT are utilized. Cold exposure is often utilized to increase BAT activity but inconsistencies in the characteristics of the exposure protocols make it challenging to compare findings. The metabolic activity of BAT in response to cold exposure has most commonly been measured by static positron emission tomography of 18F-fluorodeoxyglucose in combination with computed tomography (18F-FDG PET-CT) imaging, but recent studies suggest that under some conditions this may not always reflect BAT thermogenic activity. Therefore, recent studies have used alternative positron emission tomography and computed tomography (PET-CT) imaging strategies and radiotracers that may offer important insights. In addition to PET-CT, there are numerous emerging techniques that may have utility for assessing BAT metabolic activity including magnetic resonance imaging (MRI), skin temperature measurements, near-infrared spectroscopy (NIRS) and contrast ultrasound (CU). In this review, we discuss and critically evaluate the various methodologies used to measure BAT metabolic activity in humans and provide a contemporary assessment of protocols which may be useful in interpreting research findings and guiding the development of future studies.
Collapse
|
17
|
Emont MP, Kim DI, Wu J. Development, activation, and therapeutic potential of thermogenic adipocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:13-19. [PMID: 29763732 DOI: 10.1016/j.bbalip.2018.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/23/2018] [Accepted: 05/10/2018] [Indexed: 01/28/2023]
Abstract
During the last decade, significant progress has been made in understanding adipocytes with a particular focus on thermogenic fat cells, which effectively convert chemical energy into heat in addition to their other metabolic functions. It has been increasingly recognized that different types and subtypes of adipocytes exist and the developmental origins of various types of fat cells are being intensively investigated. Previous work using immortalized fat cell lines has established an intricate transcriptional network that regulates adipocyte function. Recent work has illustrated how these key transcriptional components mediate thermogenic activation in fat cells. Last but not least, cumulative evidence supports an incontestable role of thermogenic fat in influencing systemic metabolism in humans. Here we summarize the exciting advancements in our understanding of thermogenic fat, discuss the advantages and limitations of the experimental tools currently available, and explore the future directions of this fast-evolving field.
Collapse
Affiliation(s)
- Margo P Emont
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Dong-Il Kim
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jun Wu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA.
| |
Collapse
|
18
|
Abstract
Historically, brown adipose tissue has been elusive and not easy to detect, hence its relative obscurity in human physiology until its rediscovery in 2009. At that point, it was proven that the symmetrical artefacts frequently detected on positron emission tomography-computed tomography (PET-CT), which resolved if the environment was kept warm, were brown adipose tissue deposits. PET-CT has remained the stalwart of human brown adipose tissue research and is still considered the gold standard. However, PET-CT exposes the participant to ionising radiation, limiting studies to large, but retrospective, review of clinical imaging or a small-scale, but prospective, design. Within this context, alternative imaging modalities have been sought. Due to the heat-generating properties of brown adipose tissue, infrared thermography is a natural candidate for measuring its activity and the supraclavicular depot is relatively superficial, allowing detection of the heat signature. Infrared thermography is a non-invasive, non-contact technique for measuring temperature remotely. Recent developments in image analysis techniques have facilitated the use of infrared thermography to study brown adipose tissue activation in populations, and in ways, not previously feasible.
Collapse
|