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Abstract
Brown adipose tissue (BAT) displays the unique capacity to generate heat through uncoupled oxidative phosphorylation that makes it a very attractive therapeutic target for cardiometabolic diseases. Here, we review BAT cellular metabolism, its regulation by the central nervous and endocrine systems and circulating metabolites, the plausible roles of this tissue in human thermoregulation, energy balance, and cardiometabolic disorders, and the current knowledge on its pharmacological stimulation in humans. The current definition and measurement of BAT in human studies relies almost exclusively on BAT glucose uptake from positron emission tomography with 18F-fluorodeoxiglucose, which can be dissociated from BAT thermogenic activity, as for example in insulin-resistant states. The most important energy substrate for BAT thermogenesis is its intracellular fatty acid content mobilized from sympathetic stimulation of intracellular triglyceride lipolysis. This lipolytic BAT response is intertwined with that of white adipose (WAT) and other metabolic tissues, and cannot be independently stimulated with the drugs tested thus far. BAT is an interesting and biologically plausible target that has yet to be fully and selectively activated to increase the body's thermogenic response and shift energy balance. The field of human BAT research is in need of methods able to directly, specifically, and reliably measure BAT thermogenic capacity while also tracking the related thermogenic responses in WAT and other tissues. Until this is achieved, uncertainty will remain about the role played by this fascinating tissue in human cardiometabolic diseases.
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Affiliation(s)
- André C Carpentier
- Correspondence: André C. Carpentier, MD, Division of Endocrinology, Faculty of Medicine, University of Sherbrooke, 3001, 12th Ave N, Sherbrooke, Quebec, J1H 5N4, Canada.
| | - Denis P Blondin
- Division of Neurology, Department of Medicine, Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, J1H 5N4, Canada
| | | | - Denis Richard
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, G1V 4G5, Canada
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Averin AS, Andreeva LA, Popova SS, Kosarsky LS, Anufriev AI, Nenov MN, Nakipova OV. α1-Adrenergic receptor regulates papillary muscle and aortic segment contractile function via modulation of store-operated Ca 2+ entry in long-tailed ground squirrels Urocitellus undulatus. J Comp Physiol B 2021; 191:10.1007/s00360-021-01394-6. [PMID: 34297192 DOI: 10.1007/s00360-021-01394-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 06/28/2021] [Accepted: 07/13/2021] [Indexed: 10/20/2022]
Abstract
The effect of phenylephrine (PE) on right ventricle papillary muscle (PM) and aortic segment (AS) contractile activity was studied in long-tailed ground squirrels Urocitellus undulatus during summer activity, torpor and interbout active (IBA) periods in comparison to rat. We found that PE (10 μM) exerts positive inotropic effect on ground squirrel PM that was blocked by α1-AR inhibitor-prazosin. PE differently affected frequency dependence of PM contraction in ground squirrels and rats. PE significantly increased the force of PM contraction in summer and hibernating ground squirrels including both torpor and IBA predominantly at the range of low stimulation frequencies (0.003-0.1 Hz), while in rat PM it was evident only at high stimulation frequency range (0.2-1.0 Hz). Further, it was found that PE vasoconstrictor effect on AS contractility is significantly higher in ground squirrels of torpid state compared to IBA and summer periods. Overall vasoconstrictor effect of PE was significantly higher in AS of ground squirrels of all periods compared to rats. Positive inotropic effect of PE on PM along with its vasoconstrictor effect on AS of ground squirrels was not affected by pretreatment with inhibitors of L-type Ca2+ channels, or Na+/Ca2+ exchanger or Ca2+-ATPase but was completely blocked by an inhibitor of store-operated Ca2+ entry (SOCE)-2-APB, suggesting the involvement of SOCE in the mechanisms underlying PE action on ground squirrel cardiovascular system. Obtained results support an idea about the significant role of alpha1-AR in adaptive mechanisms critical for the maintaining of cardiovascular contractile function in long-tailed ground squirrel Urocitellus undulatus.
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Affiliation(s)
- Alexey S Averin
- Institute of Cell Biophysics Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institutskaya 3, Pushchino, Moscow region, Russia, 142290
| | - Ludmila A Andreeva
- Institute of Cell Biophysics Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institutskaya 3, Pushchino, Moscow region, Russia, 142290
| | - Svetlana S Popova
- Institute of Theoretical and Experimental Biophysics of Russian Academy of Science, Institutskaya 3, Pushchino, Moscow region, Russia, 142290
| | - Leonid S Kosarsky
- Institute of Cell Biophysics Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institutskaya 3, Pushchino, Moscow region, Russia, 142290
| | - Andrey I Anufriev
- Yakutsk Branch, Siberian Division, Institute of Biology, Russian Academy of Sciences, Yakutsk, Russia, 677891
| | - Miroslav N Nenov
- Institute of Theoretical and Experimental Biophysics of Russian Academy of Science, Institutskaya 3, Pushchino, Moscow region, Russia, 142290.
- Alzheimer's Center at Temple, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA.
| | - Olga V Nakipova
- Institute of Cell Biophysics Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institutskaya 3, Pushchino, Moscow region, Russia, 142290
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Maltsev AV. Agmatine modulates calcium handling in cardiomyocytes of hibernating ground squirrels through calcium-sensing receptor signaling. Cell Signal 2018; 51:1-12. [PMID: 30030121 DOI: 10.1016/j.cellsig.2018.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 11/20/2022]
Abstract
True hibernators are remarkable group of mammals whose hearts are resistant to such stressors as deep hypothermia, ischemia, arrhythmia. Capability of cardiac cells from hibernating species to effectively rule Ca2+ homeostasis during torpor is poorly studied. Better understanding of these mechanisms could allow to introduce new strategies for improvement the cardiac performance and may be useful for cardiovascular medicine. Here for the first time we have shown that the regulation of Ca2+ handling and thereby cardiomyocyte contractility by endogenous neurotransmitter agmatine occurs through the modulation of calcium-sensing receptor (CaSR). In isolated cardiocytes of hibernating ground squirrels generating stationary Ca2+ transients in the absence of actual myocellular excitation, low doses of this polyamine (up to 500 μM) induce the Gβγ-dependent activation of PI3-kinase with subsequent stimulation of Akt-kinase and nitric oxide (NO) production by endothelial NO-synthase (eNOS). NO production abolishes Ca2+ oscillations in virtue of the enhancement of Ca2+ reuptake by sarco(endo)plasmic Ca2+ ATPase (SERCA). Simultaneously, the activation of phospholipase A2 (PLA2) and arachidonic-acid dependent Ca2+ entry occur providing replenishment of Ca2+ store. High concentrations of agmatine (> 2 mM) induce other CaSR-mediated pathways involving phospholipase C (PLC) pathway, the formation of inositoltriphosphate (IP3) and diacylglicerol (DAG) followed by induction of their targets: IP3 receptors and protein kinase C isoforms (PKC), respectively. Furthermore, it is also responsible for the stimulation of PLA2 and elevation of intracellular calcium caused by arachidonic acid-regulated Ca2+-permeable (ARC) channels. Additionally, there is a potent store-operated Ca2+ entry (SOC) in cardiomyocyte. Negative (NPS 2143) and positive (R 568) allosteric modulators of CaSR recapitulate effects of low and high agmatine doses on Ca2+ handling and NO synthesis. These facts and the alteration of agmatine influence in response to an increase of extracellular Ca2+, which is the direct agonist of CaSR, may confirm the participation of CaSR in regulation of Ca2+ handling and excitability of cardiomyocytes by agmatine.
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Li J, Yang Q, Bai Z, Zhou W, Semenza GL, Ge RL. Chronic cold exposure results in subcutaneous adipose tissue browning and altered global metabolism in Qinghai-Tibetan plateau pika (Ochotona curzoniae). Biochem Biophys Res Commun 2018; 500:117-123. [PMID: 29626477 DOI: 10.1016/j.bbrc.2018.03.147] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 03/20/2018] [Indexed: 12/15/2022]
Abstract
The plateau pika (Ochotona curzoniae), one of the indigenous animals of the Qinghai-Tibet Plateau, is adapted to life in a cold and hypoxic environment. We conducted a series of genomic, proteomic and morphological studies to investigate whether changes in energy metabolism contribute to adaptation of the plateau pika to cold stress by analyzing summer and winter cohorts. The winter group showed strong morphological and histological features of brown adipose tissue (BAT) in subcutaneous white adipose tissue (sWAT). To obtain molecular evidence of browning of sWAT, we performed reverse transcription and quantitative real-time PCR, which revealed that BAT-specific genes, including uncoupling protein 1 (UCP-1) and PPAR-γ coactivator 1α (PGC-1α), were highly expressed in sWAT from the winter group. Compared with the summer group, Western blot analysis also confirmed that UCP-1, PGC-1α and Cox4 protein levels were significantly increased in sWAT from the winter group. Increased BAT mass in the inter-scapular region of the winter group was also observed. These results suggest that the plateau pika adapts to cold by browning sWAT and increasing BAT in order to increase thermogenesis. These changes are distinct from the previously reported adaptation of highland deer mice. Understanding the regulatory mechanisms underlying this adaptation may lead to novel therapeutic strategies for treating obesity and metabolic disorders.
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Affiliation(s)
- Jia Li
- Research Center for High Altitude Medicine, Qinghai University Medical College, 810001 Qinghai, Xining, PR China; Key Laboratory for Application of High Altitude Medicine in Qinghai Province, Qinghai University Medical College, 810001 Qinghai, Xining, PR China; Qinghai-Utah Joint Research Key Lab for High Altitude Medicine, Qinghai University Medical College, 810001 Qinghai, Xining, PR China
| | - Quanyu Yang
- Research Center for High Altitude Medicine, Qinghai University Medical College, 810001 Qinghai, Xining, PR China; Key Laboratory for Application of High Altitude Medicine in Qinghai Province, Qinghai University Medical College, 810001 Qinghai, Xining, PR China; Qinghai-Utah Joint Research Key Lab for High Altitude Medicine, Qinghai University Medical College, 810001 Qinghai, Xining, PR China
| | - Zhenzhong Bai
- Research Center for High Altitude Medicine, Qinghai University Medical College, 810001 Qinghai, Xining, PR China; Key Laboratory for Application of High Altitude Medicine in Qinghai Province, Qinghai University Medical College, 810001 Qinghai, Xining, PR China; Qinghai-Utah Joint Research Key Lab for High Altitude Medicine, Qinghai University Medical College, 810001 Qinghai, Xining, PR China.
| | - Wenhua Zhou
- Research Center for High Altitude Medicine, Qinghai University Medical College, 810001 Qinghai, Xining, PR China; Key Laboratory for Application of High Altitude Medicine in Qinghai Province, Qinghai University Medical College, 810001 Qinghai, Xining, PR China; Qinghai-Utah Joint Research Key Lab for High Altitude Medicine, Qinghai University Medical College, 810001 Qinghai, Xining, PR China
| | - Gregg L Semenza
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Departments of Pediatrics, Medicine, Oncology, Radiation Oncology, and Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Ri-Li Ge
- Research Center for High Altitude Medicine, Qinghai University Medical College, 810001 Qinghai, Xining, PR China; Key Laboratory for Application of High Altitude Medicine in Qinghai Province, Qinghai University Medical College, 810001 Qinghai, Xining, PR China; Qinghai-Utah Joint Research Key Lab for High Altitude Medicine, Qinghai University Medical College, 810001 Qinghai, Xining, PR China.
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Yang X, Sui W, Zhang M, Dong M, Lim S, Seki T, Guo Z, Fischer C, Lu H, Zhang C, Yang J, Zhang M, Wang Y, Cao C, Gao Y, Zhao X, Sun M, Sun Y, Zhuang R, Samani NJ, Zhang Y, Cao Y. Switching harmful visceral fat to beneficial energy combustion improves metabolic dysfunctions. JCI Insight 2017; 2:e89044. [PMID: 28239649 PMCID: PMC5313060 DOI: 10.1172/jci.insight.89044] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 01/05/2017] [Indexed: 01/16/2023] Open
Abstract
Visceral fat is considered the genuine and harmful white adipose tissue (WAT) that is associated to development of metabolic disorders, cardiovascular disease, and cancer. Here, we present a new concept to turn the harmful visceral fat into a beneficial energy consumption depot, which is beneficial for improvement of metabolic dysfunctions in obese mice. We show that low temperature-dependent browning of visceral fat caused decreased adipose weight, total body weight, and body mass index, despite increased food intake. In high-fat diet-fed mice, low temperature exposure improved browning of visceral fat, global metabolism via nonshivering thermogenesis, insulin sensitivity, and hepatic steatosis. Genome-wide expression profiling showed upregulation of WAT browning-related genes including Cidea and Dio2. Conversely, Prdm16 was unchanged in healthy mice or was downregulated in obese mice. Surgical removal of visceral fat and genetic knockdown of UCP1 in epididymal fat largely ablated low temperature-increased global thermogenesis and resulted in the death of most mice. Thus, browning of visceral fat may be a compensatory heating mechanism that could provide a novel therapeutic strategy for treating visceral fat-associated obesity and diabetes.
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Affiliation(s)
- Xiaoyan Yang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong, China
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
- Department of Cardiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Wenhai Sui
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong, China
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Meng Zhang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong, China
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Mei Dong
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong, China
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Sharon Lim
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Takahiro Seki
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Ziheng Guo
- West China School of Medicine, Sichuan University, Chengdu, China
| | - Carina Fischer
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Huixia Lu
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong, China
| | - Cheng Zhang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong, China
| | - Jianmin Yang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong, China
| | - Meng Zhang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong, China
| | - Yangang Wang
- Department of Endocrinology and Metabolism, Affiliated Hospital of Qingdao University, Qingdao, China
| | - Caixia Cao
- Department of Endocrinology and Metabolism, Affiliated Hospital of Qingdao University, Qingdao, China
| | - Yanyan Gao
- Department of Endocrinology and Metabolism, Affiliated Hospital of Qingdao University, Qingdao, China
| | - Xingguo Zhao
- Department of Otolaryngology, Shandong University Qilu Hospital, Jinan, Shandong, China
| | - Meili Sun
- Department of Oncology, Jinan Central Hospital, Shandong University, Jinan, Shandong, China
| | - Yuping Sun
- Department of Oncology, Jinan Central Hospital, Shandong University, Jinan, Shandong, China
| | - Rujie Zhuang
- The TCM Hospital of Zhejiang Province, Hangzhou, Zhejiang, China
| | - Nilesh J. Samani
- Department of Cardiovascular Sciences, University of Leicester and NIHR Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom
| | - Yun Zhang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong, China
| | - Yihai Cao
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong, China
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
- Department of Cardiovascular Sciences, University of Leicester and NIHR Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom
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Hampton M, Melvin RG, Andrews MT. Transcriptomic analysis of brown adipose tissue across the physiological extremes of natural hibernation. PLoS One 2013; 8:e85157. [PMID: 24386461 PMCID: PMC3875542 DOI: 10.1371/journal.pone.0085157] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 11/23/2013] [Indexed: 11/18/2022] Open
Abstract
We used RNAseq to generate a comprehensive transcriptome of Brown Adipose Tissue (BAT) over the course of a year in the naturally hibernating thirteen-lined ground squirrel, Ictidomys tridecemlineatus. During hibernation ground squirrels do not feed and use fat stored in White Adipose Tissue (WAT) as their primary source of fuel. Stored lipid is consumed at high rates by BAT to generate heat at specific points during the hibernation season. The highest rate of BAT activity occurs during periodic arousals from hypothermic torpor bouts, referred to as Interbout Arousals (IBAs). IBAs are characterized by whole body re-warming (from 5 to 37 °C) in 2-3 hours, and provide a unique opportunity to determine the genes responsible for the highly efficient lipid oxidation and heat generation that drives the arousal process. Illumina HighSeq sequencing identified 14,573 distinct BAT mRNAs and quantified their levels at four points: active ground squirrels in April and October, and hibernating animals during both torpor and IBA. Based on significant changes in mRNA levels across the four collection points, 2,083 genes were shown to be differentially expressed. In addition to providing detail on the expression of nuclear genes encoding mitochondrial proteins, and genes involved in beta-adrenergic and lipolytic pathways, we identified differentially expressed genes encoding various transcription factors and other regulatory proteins which may play critical roles in high efficiency fat catabolism, non-shivering thermogenesis, and transitions into and out of the torpid state.
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Affiliation(s)
- Marshall Hampton
- Department of Mathematics and Statistics, University of Minnesota Duluth, Duluth, Minnesota, United States of America
| | - Richard G. Melvin
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota, United States of America
| | - Matthew T. Andrews
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota, United States of America
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Abstract
Sleep duration has progressively fallen over the last 100 years while obesity has increased in the past 30 years. Several studies have reported an association between chronic sleep deprivation and long-term weight gain. Increased energy intake due to sleep loss has been listed as the main mechanism. The consequences of chronic sleep deprivation on energy expenditure have not been fully explored. Sleep, body weight, mood and behavior are subjected to circannual changes. However, in our modern environment seasonal changes in light and ambient temperature are attenuated. Seasonality, defined as cyclic changes in mood and behavior, is a stable personality trait with a strong genetic component. We hypothesize that the attenuation in seasonal changes in the environment may produce negative consequences, especially in individuals more predisposed to seasonality, such as women. Seasonal affective disorder, a condition more common in women and characterized by depressed mood, hypersomnia, weight gain, and carbohydrate craving during the winter, represents an extreme example of seasonality. One of the postulated functions of sleep is energy preservation. Hibernation, a phenomenon characterized by decreased energy expenditure and changes in the state of arousal, may offer useful insight into the mechanisms behind energy preservation during sleep. The goals of this article are to: a) consider the contribution of changes in energy expenditure to the weight gain due to sleep loss; b) review the phenomena of seasonality, hibernation, and their neuroendocrine mechanisms as they relate to sleep, energy expenditure, and body weight regulation.
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Affiliation(s)
- G Cizza
- Section on Neuroendocrinology of Obesity, NIDDK, Bethesda, MD, USA.
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Kitao N, Hashimoto M. Increased thermogenic capacity of brown adipose tissue under low temperature and its contribution to arousal from hibernation in Syrian hamsters. Am J Physiol Regul Integr Comp Physiol 2011; 302:R118-25. [PMID: 21993529 DOI: 10.1152/ajpregu.00053.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Brown adipose tissue (BAT) is thought to play a significant physiological role during arousal when body temperature rises from the extremely low body temperature that occurs during hibernation. The dominant pathway of BAT thermogenesis occurs through the β(3)-adrenergic receptor. In this study, we investigated the role of the β(3)-adrenergic system in BAT thermogenesis during arousal from hibernation both in vitro and in vivo. Syrian hamsters in the hibernation group contained BAT that was significantly greater in overall mass, total protein, and thermogenic uncoupling protein-1 than BAT from the warm-acclimated group. Although the ability of the β(3)-agonist CL316,243 to induce BAT thermogenesis at 36°C was no different between the hibernation and warm-acclimated groups, its maximum ratio over the basal value at 12°C in the hibernation group was significantly larger than that in the warm-acclimated group. Forskolin stimulation at 12°C produced equivalent BAT responses in these two groups. In vivo thermogenesis was assessed with the arousal time determined by the time course of BAT temperature or heart rate. Stimulation of BAT by CL316,243 significantly shortened the time of arousal from hibernation compared with that induced by vehicle alone, and it also induced arousal in deep hibernating animals. The β(3)-antagonist SR59230A inhibited arousal from hibernation either in part or completely. These results suggest that BAT in hibernating animals has potent thermogenic activity with a highly effective β(3)-receptor mechanism at lower temperatures.
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Affiliation(s)
- Naoya Kitao
- Department of Physiology, Asahikawa Medical University, Japan
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