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Przygodda F, Lautherbach N, Buzelle SL, Goncalves DA, Assis AP, Paula-Gomes S, Garófalo MAR, Heck LC, Matsuo FS, Mota RF, Osako MK, Kettelhut IC, Navegantes LC. Sympathetic innervation suppresses the autophagic-lysosomal system in brown adipose tissue under basal and cold-stimulated conditions. J Appl Physiol (1985) 2020; 128:855-871. [PMID: 32027543 DOI: 10.1152/japplphysiol.00065.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The sympathetic nervous system (SNS) activates cAMP signaling and promotes trophic effects on brown adipose tissue (BAT) through poorly understood mechanisms. Because norepinephrine has been found to induce antiproteolytic effects on muscle and heart, we hypothesized that the SNS could inhibit autophagy in interscapular BAT (IBAT). Here, we describe that selective sympathetic denervation of rat IBAT kept at 25°C induced atrophy, and in parallel dephosphorylated forkhead box class O (FoxO), and increased cathepsin activity, autophagic flux, autophagosome formation, and expression of autophagy-related genes. Conversely, cold stimulus (4°C) for up to 72 h induced thermogenesis and IBAT hypertrophy, an anabolic effect that was associated with inhibition of cathepsin activity, autophagic flux, and autophagosome formation. These effects were abrogated by sympathetic denervation, which also upregulated Gabarapl1 mRNA. In addition, the cold-driven sympathetic activation stimulated the mechanistic target of rapamycin (mTOR) pathway, leading to the enhancement of protein synthesis, evaluated in vivo by puromycin incorporation, and to the inhibitory phosphorylation of Unc51-like kinase-1, a key protein in the initiation of autophagy. This coincided with a higher content of exchange protein-1 directly activated by cAMP (Epac1), a cAMP effector, and phosphorylation of Akt at Thr308, all these effects being abolished by denervation. Systemic treatment with norepinephrine for 72 h mimicked most of the cold effects on IBAT. These data suggest that the noradrenergic sympathetic inputs to IBAT restrain basal autophagy via suppression of FoxO and, in the setting of cold, stimulate protein synthesis via the Epac/Akt/mTOR-dependent pathway and suppress the autophagosome formation, probably through posttranscriptional mechanisms.NEW & NOTEWORTHY The underlying mechanisms related to the anabolic role of sympathetic innervation on brown adipose tissue (BAT) are unclear. We show that sympathetic denervation activates autophagic-lysosomal degradation, leading to a loss of mitochondrial proteins and BAT atrophy. Conversely, cold-driven sympathetic activation suppresses autophagy and stimulates protein synthesis, leading to BAT hypertrophy. Given its high-potential capacity for heat production, understanding the mechanisms that contribute to BAT mass is important to optimize chances of survival for endotherms in cold ambients.
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Affiliation(s)
- Franciele Przygodda
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Natalia Lautherbach
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Samyra Lopes Buzelle
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Dawit Albieiro Goncalves
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.,Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Ana Paula Assis
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Sílvia Paula-Gomes
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | | | - Lilian Carmo Heck
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Flávia Sayuri Matsuo
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Ryerson Fonseca Mota
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Mariana Kiomy Osako
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Isis C Kettelhut
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Luiz C Navegantes
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
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2
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François M, Torres H, Huesing C, Zhang R, Saurage C, Lee N, Qualls-Creekmore E, Yu S, Morrison CD, Burk D, Berthoud HR, Münzberg H. Sympathetic innervation of the interscapular brown adipose tissue in mouse. Ann N Y Acad Sci 2019; 1454:3-13. [PMID: 31184376 PMCID: PMC6810755 DOI: 10.1111/nyas.14119] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 04/05/2019] [Accepted: 04/24/2019] [Indexed: 12/11/2022]
Abstract
The recent discovery of significant brown fat depots in adult humans has revived discussion of exploiting brown fat thermogenesis in the control of energy balance and body weight. The sympathetic nervous system (SNS) has a key role in the activation of brown fat and functional mapping of its components will be crucial for the development of specific neuromodulation techniques. The mouse is an important species used for molecular genetic modulations, but its small size is not ideal for anatomical dissections, thus brown fat innervation studies are mostly available in larger rodents such as rats and hamsters. Here, we use pseudorabies virus retrograde tracing, whole tissue clearing, and confocal/light sheet microscopy to show the location of pre- and postganglionic neurons selectively innervating the interscapular brown adipose tissue (iBAT) in the mouse. Using iDISCO whole tissue clearing, we identified iBAT projecting postganglionic neurons in the caudal parts of the ipsilateral fused stellate/T1, as well as the T2-T5 sympathetic chain ganglia and preganglionic neurons between levels T2 and T6 of the ipsilateral spinal cord. The methodology enabled high-resolution imaging and 3D rendering of the specific SNS innervation of iBAT and will be helpful to discern peripheral nervous system innervation of other organs and tissues.
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Affiliation(s)
- Marie François
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Hayden Torres
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Clara Huesing
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Rui Zhang
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Carson Saurage
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Nathan Lee
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Emily Qualls-Creekmore
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Sangho Yu
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Christopher D Morrison
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - David Burk
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Hans Rudolf Berthoud
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Heike Münzberg
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
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3
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Radi ZA, Vogel WM, Bartholomew PM, Koza-Taylor P, Papanikolaou A, Wisialowski T, Nambiar P, Ball DJ. Cellular and functional actions of tofacitinib related to the pathophysiology of hibernoma development. Regul Toxicol Pharmacol 2017; 91:93-102. [PMID: 29074274 DOI: 10.1016/j.yrtph.2017.10.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 10/19/2017] [Indexed: 12/26/2022]
Abstract
Tofacitinib is an oral JAK inhibitor for the treatment of rheumatoid arthritis. In the 2-year carcinogenicity study with tofacitinib, increased incidence of hibernoma (a neoplasm of brown adipose tissue [BAT]) was noted in female rats at ≥30 mg/kg/day (≥41x human exposure multiples). Thus, signaling pathways within BAT were investigated by measuring BAT: weight, cell proliferation biomarkers, content of basal and prolactin-induced phosphorylated Signal Transducer and Activator of Transcription (STAT), and uncoupling protein 1 (UCP-1). The relationship between cardiovascular hemodynamics and plasma norepinephrine (NE) levels was also investigated. Tofacitinib administered to female rats at doses of 10, 30, or 75 mg/kg/day for 14 days increased BAT weight at 75 mg/kg/day and cell proliferation at ≥30 mg/kg/day. JAK inhibition, observed as lower pSTAT3 and pSTAT5 in BAT, was noted at ≥10 mg/kg/day, while lower activity of BAT was observed as lower UCP-1 protein at ≥30 mg/kg/day. In cultured brown adipocytes, prolactin-induced increase in pSTAT5 and pSTAT3 were inhibited by tofacitinib in a concentration-dependent manner. Tofacitinib lowered blood pressure, increased heart rate, and resulted in dose-dependent increases in circulating NE. Thus, JAK/STAT inhibition in BAT and sympathetic stimulation are two factors which might contribute to the genesis of hibernomas by tofacitinib in rats.
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Affiliation(s)
- Zaher A Radi
- Pfizer Worldwide Research and Development, Drug Safety R&D, One Burtt Road, Andover, MA 01810, USA.
| | - W Mark Vogel
- Pfizer Worldwide Research and Development, Drug Safety R&D, One Burtt Road, Andover, MA 01810, USA
| | - Phillip M Bartholomew
- Pfizer Worldwide Research and Development, Drug Safety R&D, Eastern Point Road, Groton, CT 06340, USA
| | - Petra Koza-Taylor
- Pfizer Worldwide Research and Development, Drug Safety R&D, Eastern Point Road, Groton, CT 06340, USA
| | - Alexandros Papanikolaou
- Pfizer Worldwide Research and Development, Drug Safety R&D, Eastern Point Road, Groton, CT 06340, USA
| | - Todd Wisialowski
- Pfizer Worldwide Research and Development, Drug Safety R&D, Eastern Point Road, Groton, CT 06340, USA
| | - Prashant Nambiar
- Pfizer Worldwide Research and Development, Drug Safety R&D, One Burtt Road, Andover, MA 01810, USA
| | - Douglas J Ball
- Pfizer Worldwide Research and Development, Drug Safety R&D, Eastern Point Road, Groton, CT 06340, USA
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4
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Sampath SC, Sampath SC, Bredella MA, Cypess AM, Torriani M. Imaging of Brown Adipose Tissue: State of the Art. Radiology 2017; 280:4-19. [PMID: 27322970 DOI: 10.1148/radiol.2016150390] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The rates of diabetes, obesity, and metabolic disease have reached epidemic proportions worldwide. In recent years there has been renewed interest in combating these diseases not only by modifying energy intake and lifestyle factors, but also by inducing endogenous energy expenditure. This approach has largely been stimulated by the recent recognition that brown adipose tissue (BAT)-long known to promote heat production and energy expenditure in infants and hibernating mammals-also exists in adult humans. This landmark finding relied on the use of clinical fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography, and imaging techniques continue to play a crucial and increasingly central role in understanding BAT physiology and function. Herein, the authors review the origins of BAT imaging, discuss current preclinical and clinical strategies for imaging BAT, and discuss imaging methods that will provide crucial insight into metabolic disease and how it may be treated by modulating BAT activity. (©) RSNA, 2016.
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Affiliation(s)
- Srihari C Sampath
- From Musculoskeletal Biology and Bioimaging, Department of Pharmacology, Genomics Institute of the Novartis Research Foundation, San Diego, Calif (Srihari Sampath, Srinath Sampath); Division of Musculoskeletal Imaging and Intervention, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Yawkey 6E, Boston, MA 02114 (M.B., M.T.); and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Md (A.M.C.)
| | - Srinath C Sampath
- From Musculoskeletal Biology and Bioimaging, Department of Pharmacology, Genomics Institute of the Novartis Research Foundation, San Diego, Calif (Srihari Sampath, Srinath Sampath); Division of Musculoskeletal Imaging and Intervention, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Yawkey 6E, Boston, MA 02114 (M.B., M.T.); and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Md (A.M.C.)
| | - Miriam A Bredella
- From Musculoskeletal Biology and Bioimaging, Department of Pharmacology, Genomics Institute of the Novartis Research Foundation, San Diego, Calif (Srihari Sampath, Srinath Sampath); Division of Musculoskeletal Imaging and Intervention, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Yawkey 6E, Boston, MA 02114 (M.B., M.T.); and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Md (A.M.C.)
| | - Aaron M Cypess
- From Musculoskeletal Biology and Bioimaging, Department of Pharmacology, Genomics Institute of the Novartis Research Foundation, San Diego, Calif (Srihari Sampath, Srinath Sampath); Division of Musculoskeletal Imaging and Intervention, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Yawkey 6E, Boston, MA 02114 (M.B., M.T.); and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Md (A.M.C.)
| | - Martin Torriani
- From Musculoskeletal Biology and Bioimaging, Department of Pharmacology, Genomics Institute of the Novartis Research Foundation, San Diego, Calif (Srihari Sampath, Srinath Sampath); Division of Musculoskeletal Imaging and Intervention, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Yawkey 6E, Boston, MA 02114 (M.B., M.T.); and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Md (A.M.C.)
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5
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Mukaida S, Evans BA, Bengtsson T, Hutchinson DS, Sato M. Adrenoceptors promote glucose uptake into adipocytes and muscle by an insulin-independent signaling pathway involving mechanistic target of rapamycin complex 2. Pharmacol Res 2016; 116:87-92. [PMID: 28025104 DOI: 10.1016/j.phrs.2016.12.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 11/12/2016] [Accepted: 12/13/2016] [Indexed: 12/15/2022]
Abstract
Uptake of glucose into skeletal muscle and adipose tissue plays a vital role in metabolism and energy balance. Insulin released from β-islet cells of the pancreas promotes glucose uptake in these target tissues by stimulating translocation of GLUT4 transporters to the cell surface. This process is complex, involving signaling proteins including the mechanistic (or mammalian) target of rapamycin (mTOR) and Akt that intersect with multiple pathways controlling cell survival, growth and proliferation. mTOR exists in two forms, mTOR complex 1 (mTORC1), and mTOR complex 2 (mTORC2). mTORC1 has been intensively studied, acting as a key regulator of protein and lipid synthesis that integrates cellular nutrient availability and energy balance. Studies on mTORC2 have focused largely on its capacity to activate Akt by phosphorylation at Ser473, however recent findings demonstrate a novel role for mTORC2 in cellular glucose uptake. For example, agonists acting at β2-adrenoceptors (ARs) in skeletal muscle or β3-ARs in brown adipose tissue increase glucose uptake in vitro and in vivo via mechanisms dependent on mTORC2 but not Akt. In this review, we will focus on the signaling pathways downstream of β-ARs that promote glucose uptake in skeletal muscle and brown adipocytes, and will highlight how the insulin and adrenergic pathways converge and interact in these cells. The identification of insulin-independent mechanisms that promote glucose uptake should facilitate novel treatment strategies for metabolic disease.
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Affiliation(s)
- Saori Mukaida
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Bronwyn A Evans
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Tore Bengtsson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
| | - Dana S Hutchinson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Masaaki Sato
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.
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6
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Poulet FM, Berardi MR, Halliwell W, Hartman B, Auletta C, Bolte H. Development of Hibernomas in Rats Dosed with Phentolamine Mesylate During the 24-Month Carcinogenicity Study. Toxicol Pathol 2016; 32:558-66. [PMID: 15603540 DOI: 10.1080/01926230490505086] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Phentolamine is a reversible competitive α-adrenergic antagonist with similar affinities for α1 and α2 receptors. It has a long history of safe clinical use, and was developed as a potential therapy for male erectile dysfunction because of its capacity to increase the arteriolar blood flow to the corpora cavernosa. Phentolamine mesylate was administered to rats by oral gavage at daily doses of 10, 50, and 150 mg/kg for 24 months. A dose-related increase in mortality, ascribed to an exaggerated pharmacologic effect, was seen at high doses. Systemic exposure as measured by plasma drug concentration increased with dose and duration of dosing and slight drug accumulation occurred, particularly in high-dose males. In the treated groups, 10 males and 1 female were diagnosed with hibernomas, neoplasms of brown adipose tissue, which appeared in the thoracic cavity or retroperitoneal area as circumscribed, tan to reddish-brown lobulated masses. Histologically, the masses were well circumscribed with variably sized lobules defined by a rich capillary network and consisted of closely apposed oval to polygonal cells with large amounts of cytoplasm and a centrally located nucleus. The cytoplasm's appearance varied from multivacuolated to univacuolated to granular eosinophilic. In a few cases, neoplastic emboli were observed in capsular vessels. Ultrastructurally, the neoplastic cells contained numerous mitochondria with transverse parallel cristae that occupied over 60% of the cytoplasm and lipid droplets. This study documents the previously unreported development of hibernomas in rats treated with phentolamine mesylate.
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Abstract
The continuous rise in obesity is a major concern for future healthcare management. Many strategies to control body weight focus on a permanent modification of food intake with limited success in the long term. Metabolism or energy expenditure is the other side of the coin for the regulation of body weight, and strategies to enhance energy expenditure are a current focus for obesity treatment, especially since the (re)-discovery of the energy depleting brown adipose tissue in adult humans. Conversely, several human illnesses like neurodegenerative diseases, cancer, or autoimmune deficiency syndrome suffer from increased energy expenditure and severe weight loss. Thus, strategies to modulate energy expenditure to target weight gain or loss would improve life expectancies and quality of life in many human patients. The aim of this book chapter is to give an overview of our current understanding and recent progress in energy expenditure control with specific emphasis on central control mechanisms.
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Radi Z, Bartholomew P, Elwell M, Vogel WM. Comparative pathophysiology, toxicology, and human cancer risk assessment of pharmaceutical-induced hibernoma. Toxicol Appl Pharmacol 2013; 273:456-63. [PMID: 24141031 DOI: 10.1016/j.taap.2013.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 10/05/2013] [Accepted: 10/09/2013] [Indexed: 01/26/2023]
Abstract
In humans, hibernoma is a very rare, benign neoplasm of brown adipose tissue (BAT) that typically occurs at subcutaneous locations and is successfully treated by surgical excision. No single cause has been accepted to explain these very rare human tumors. In contrast, spontaneous hibernoma in rats is rare, often malignant, usually occurs in the thoracic or abdominal cavity, and metastases are common. In recent years, there has been an increased incidence of spontaneous hibernomas in rat carcinogenicity studies, but overall the occurrence remains relatively low and highly variable across studies. There have only been four reported examples of pharmaceutical-induced hibernoma in rat carcinogenicity studies. These include phentolamine, an alpha-adrenergic antagonist; varenicline, a nicotine partial agonist; tofacitinib, a Janus kinase (JAK) inhibitor; and hydromorphone, an opiod analgesic. Potential non-genotoxic mechanisms that may contribute to the pathogenesis of BAT activation/proliferation and/or subsequent hibernoma development in rats include: (1) physiological stimuli, (2) sympathetic stimulation, (3) peroxisome proliferator-activated receptor (PPAR) agonism, and/or (4) interference or inhibition of JAK/Signal Transducer and Activator of Transcription (JAK/STAT) signaling. The evaluation of an apparent increase of hibernoma in rats from 2-year carcinogenicity studies of novel pharmaceutical therapeutics and its relevance to human safety risk assessment is complex. One should consider: the genotoxicity of the test article, dose/exposure and safety margins, and pathophysiologic and morphologic differences and similarities of hibernoma between rats and humans. Hibernomas observed to date in carcinogenicity studies of pharmaceutical agents do not appear to be relevant for human risk at therapeutic dosages.
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Affiliation(s)
- Zaher Radi
- Pfizer Worldwide Research and Development, Drug Safety R&D, 1 Burtt Rd., Andover, MA 01810, USA.
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9
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Ravi M, Schobert CS, Kiupel M, Dubielzig RR. Clinical, morphologic, and immunohistochemical features of canine orbital hibernomas. Vet Pathol 2013; 51:563-8. [PMID: 23794150 DOI: 10.1177/0300985813493913] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hibernomas are uncommon benign tumors of brown fat that occur in humans and various animal species. They have not been observed in the orbit of dogs, humans, or other animals. Here we report clinical, light and electron microscopic, and immunohistochemical features of a series of 7 hibernomas arising in the orbital region of dogs. These neoplasms occurred in adult dogs with no breed predilection. The mean age of the affected dogs was 10.4 years (range, 8-13 years). All neoplasms presented as soft lobular masses composed of predominantly round or polygonal neoplastic cells with granular eosinophilic and vacuolated cytoplasm resembling adipocytes. The cytoplasm contained large numbers of pleomorphic mitochondria with dense matrices and indistinct cristae. Immunohistochemical evaluation confirmed positive labeling of neoplastic cells from all cases with uncoupling protein 1 (UCP-1) consistent with brown fat differentiation. Interestingly, rare neoplastic cells also expressed myogenin and myoD, possibly suggesting a common progenitor cell for neoplastic brown adipose and skeletal muscle cells.
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Affiliation(s)
- M Ravi
- Alberta Agriculture and Rural Development, OS Longman Bldg, 6909 112 St, Edmonton, Alberta T6H 4P2, Canada.
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Huang YC, Hsu CC, Wang PW, Chang YH, Chen TB, Lee BF, Chiu NT. Review analysis of the association between the prevalence of activated brown adipose tissue and outdoor temperature. ScientificWorldJournal 2012; 2012:793039. [PMID: 22593707 PMCID: PMC3349155 DOI: 10.1100/2012/793039] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 12/21/2011] [Indexed: 01/19/2023] Open
Abstract
Brown adipose tissue (BAT) is important for regulating body weight. Environmental temperature influences BAT activation. Activated BAT is identifiable using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). 18F-FDG PET/CT scans done between June 2005 and May 2009 in our institution in tropical southern Taiwan and BAT studies from PubMed (2002–2011) were reviewed, and the average outdoor temperatures during the study periods were obtained. A simple linear regression was used to analyze the association between the prevalence of activated BAT (P) and the average outdoor temperature (T). The review analysis for 9 BAT studies (n = 16, 765) showed a significant negative correlation (r = −0.741, P = 0.022) between the prevalence of activated BAT and the average outdoor temperature. The equation of the regression line is P(%) = 6.99 − 0.20 × T (°C). The prevalence of activated BAT decreased by 1% for each 5°C increase in average outdoor temperature. In a neutral ambient temperature, the prevalence of activated BAT is low and especially rare in the tropics. There is a significant linear negative correlation between the prevalence of activated BAT and the average outdoor temperature.
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Affiliation(s)
- Yung-Cheng Huang
- Department of Nuclear Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 83301, Taiwan
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11
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Brees DJ, Elwell MR, Tingley FD, Sands SB, Jakowski AB, Shen AC, Cai JH, Finkelstein MB. Pharmacological Effects of Nicotine on Norepinephrine Metabolism in Rat Brown Adipose Tissue: Relevance to Nicotinic Therapies for Smoking Cessation. Toxicol Pathol 2008; 36:568-75. [DOI: 10.1177/0192623308317424] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In a two-year carcinogenicity study with administration of high doses of the partial nicotinic agonist varenicline (recently approved for smoking cessation), mediastinal hibernomas occurred in three male rats. To investigate potential mechanisms for partial and full nicotinic agonists to contribute to development of hibernomas, the effects of nicotine on rat brown adipose tissue (BAT) were studied. Male and female rats were administered nicotine at doses of 0, 0.3, and 1 mg/kg subcutaneously for fourteen days. Intrathoracic (mediastinal periaortic and mediastinal perithymic) BAT and interscapular BAT were examined microscopically, and determinations of uncoupling protein-1 (UCP-1) expression and norepinephrine (NE) content were made. Additionally, NE turnover was measured in mediastinal periaortic and perithymic BAT. Nicotine (1 mg/kg) administration resulted in decreased vacuolation only in mediastinal periaortic and mediastinal perithymic BAT of males and elevated UCP-1 in mediastinal periaortic BAT of males and females. Increased NE content occurred only in mediastinal periaortic BAT of males given 0.3 and 1 mg/kg doses, whereas NE turnover was decreased in both males and females given 1 mg/kg. Together, these data demonstrate that nicotine primarily affects mediastinal BAT in male rats, consistent with the gender and location of the hibernomas observed in the two-year carcinogenicity study.
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Affiliation(s)
| | | | - F. David Tingley
- Pfizer Global Research and Development, Groton, Connecticut, USA
| | - Steven B. Sands
- Pfizer Global Research and Development, Groton, Connecticut, USA
| | - Amy B. Jakowski
- Pfizer Global Research and Development, Groton, Connecticut, USA
| | - Amy C. Shen
- Pfizer Global Research and Development, Groton, Connecticut, USA
| | - Jenny Hon Cai
- Pfizer Global Research and Development, Groton, Connecticut, USA
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12
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Mori S, Yoshizuka N, Takizawa M, Takema Y, Murase T, Tokimitsu I, Saito M. Expression of uncoupling proteins in human skin and skin-derived cells. J Invest Dermatol 2008; 128:1894-900. [PMID: 18305572 DOI: 10.1038/jid.2008.20] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Uncoupling protein (UCP) is a mitochondrial membrane protein that uncouples oxidative phosphorylation. The physiological function of major isoforms of UCPs is related to the control of body temperature and reactive oxygen species production. Although skin is an important organ for heat radiation and protection against stress, the expression and function of UCPs in the skin have remained unclear. The expression of UCPs in human skin and its derived cells was researched at the mRNA and protein levels. The effects of norepinephrine (NE) and 9-cis retinoic acid (RA) on UCP expression were also investigated. The expression of UCP1 mRNA was found in the human epidermis and was upregulated in differentiated keratinocytes. UCP1 expression in keratinocytes was synergistically upregulated by NE and RA treatment. Significant expression of UCP2 and UCP3 was observed also in cultured keratinocytes and fibroblasts. By immunohistochemistry, localization of UCP1 was found in the granular layer of the epidermis, sweat glands, hair follicles, and sebaceous glands of various sites in the human body. UCP3 was widely found in the dermis. This showed that UCPs exist in human skin, with their expression being under hormonal control. These findings are in stark contrast with the well-accepted view of UCP1 expression being exclusive to brown adipose tissue.
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Affiliation(s)
- Shinobu Mori
- Biological Science Laboratories, Kao Corporation, Tochigi, Japan.
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13
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Oi-KANO Y, KAWADA T, WATANABE T, KOYAMA F, WATANABE K, SENBONGI R, IWAI K. Oleuropein, a Phenolic Compound in Extra Virgin Olive Oil, Increases Uncoupling Protein 1 Content in Brown Adipose Tissue and Enhances Noradrenaline and Adrenaline Secretions in Rats. J Nutr Sci Vitaminol (Tokyo) 2008; 54:363-70. [DOI: 10.3177/jnsv.54.363] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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14
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Oi-Kano Y, Kawada T, Watanabe T, Koyama F, Watanabe K, Senbongi R, Iwai K. Extra virgin olive oil increases uncoupling protein 1 content in brown adipose tissue and enhances noradrenaline and adrenaline secretions in rats. J Nutr Biochem 2007; 18:685-92. [PMID: 17418557 DOI: 10.1016/j.jnutbio.2006.11.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 11/05/2006] [Accepted: 11/10/2006] [Indexed: 10/23/2022]
Abstract
The effects of extra virgin olive oil (EV-olive oil) on triglyceride metabolism were investigated by measuring the degree of thermogenesis in interscapular brown adipose tissue (IBAT) and the rates of noradrenaline and adrenaline secretions in rats, both in vivo and in situ. In Experiment 1 (in vivo), rats were given an isoenergetic high-fat diet (30% fat diet) containing corn oil, refined olive oil, or EV-olive oil. After 28 days of feeding, the final body weight, weight gain, energy efficiency, perirenal adipose tissue and epididymal fat pad and plasma triglyceride concentrations were the lowest in the rats fed the EV-olive oil diet. The content of uncoupling protein 1 (UCP1) in IBAT and the rates of urinary noradrenaline and adrenaline excretions were the highest in the rats fed the EV-olive oil diet. In Experiment 2 (in situ), the effects of the extract of the phenolic fraction from EV-olive oil and a compound having excellent characteristics as components of EV-olive oil, hydroxytyrosol, on noradrenaline and adrenaline secretions were evaluated. The intravenous administration of the extract of the phenolic fraction from EV-olive oil significantly increased plasma noradrenaline and adrenaline concentrations, whereas that of hydroxytyrosol had no effect. These results suggest that phenols except hydroxytyrosol in EV-olive oil enhance thermogenesis by increasing the UCP1 content in IBAT and enhancing noradrenaline and adrenaline secretions in rats.
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Affiliation(s)
- Yuriko Oi-Kano
- Laboratory of Nutrition Chemistry, Faculty of Home Economics, Kobe Women's University, 2-1 Aoyama, Higashisuma, Suma-ku, Kobe 654-8585, Japan.
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15
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Go AGG, Chow KHM, Hwang ISS, Tang F. Adrenomedullin and its receptor components in adipose tissues: Differences between white and brown fats and the effects of adrenergic stimulation. Peptides 2007; 28:920-7. [PMID: 17250927 DOI: 10.1016/j.peptides.2006.12.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Revised: 12/06/2006] [Accepted: 12/07/2006] [Indexed: 11/22/2022]
Abstract
Male Sprague-Dawley rats were subcutaneously injected with 2.5mg/kg phenylephrine or 2.5mg/kg isoproterenol or both (2.5mg/kg for each drug) for 4 days, twice a day. Samples of scapular brown adipose tissue (BAT) and epididymal white adipose tissue (WAT) were collected for the measurement of adrenomedullin (AM) levels and the gene expression of preproAM, calcitonin receptor like receptor (CRLR) and its activity modifying proteins (RAMPs) by radioimmunoassay and RT-PCR. These values were compared with those in the rats that received 0.9% saline. The gene expression of AM and AM receptor components in BAT are much less than that in epididymal WAT. In BAT there were an increase in AM peptide level after a combined treatment of alpha(1) and beta adrenoceptor agonists and increases in preproAM mRNA levels for rats treated with alpha(1) and beta receptor agonists alone or in combination. Both CRLR and RAMP2 mRNA levels of alphabeta group were increased significantly. In WAT, AM peptide level, RAMP1 and RAMP2 mRNA expression levels were augmented in the alpha group while CRLR mRNA level was enhanced in the beta group. The levels of AM, its receptor and RAMPs are much less in BAT than in WAT but adrenergic stimulation has a greater effect on the AM and its receptor components in BAT than those in WAT. AM stimulates lipolysis and increases the level of uncoupling protein-1 (UCP-1) in BAT. It may therefore enhance thermogenesis by increasing the availability of free fatty acids substrate as well as the UCP-1 level on the mitochondrial membrane.
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MESH Headings
- Adipose Tissue, Brown/chemistry
- Adipose Tissue, Brown/drug effects
- Adipose Tissue, Brown/metabolism
- Adipose Tissue, White/chemistry
- Adipose Tissue, White/drug effects
- Adipose Tissue, White/metabolism
- Adrenergic Agents/administration & dosage
- Adrenergic Agents/pharmacology
- Adrenomedullin/genetics
- Adrenomedullin/metabolism
- Animals
- Blotting, Western
- Body Weight/drug effects
- Calcitonin Receptor-Like Protein
- Gene Expression Regulation/drug effects
- Injections, Subcutaneous
- Intracellular Signaling Peptides and Proteins/genetics
- Intracellular Signaling Peptides and Proteins/metabolism
- Ion Channels/metabolism
- Isoproterenol/administration & dosage
- Isoproterenol/pharmacology
- Lipolysis/drug effects
- Male
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mitochondrial Proteins/metabolism
- Phenylephrine/administration & dosage
- Phenylephrine/pharmacology
- Protein Precursors/genetics
- Protein Precursors/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Radioimmunoassay
- Rats
- Rats, Sprague-Dawley
- Receptor Activity-Modifying Proteins
- Receptors, Adrenomedullin
- Receptors, Calcitonin/genetics
- Receptors, Calcitonin/metabolism
- Receptors, Peptide/genetics
- Receptors, Peptide/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Uncoupling Protein 1
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Affiliation(s)
- Adi G G Go
- Department of Physiology, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong, China
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16
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Suzuki D, Murata Y, Oda SI. Change in Ucp1 mRNA Expression Following Long-Term Cold Exposure under Normal or High-Fat Diet Regimes in the Cold-Intolerant Mammal, Suncus murinus. Exp Anim 2006; 55:467-71. [PMID: 17090963 DOI: 10.1538/expanim.55.467] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The house musk shrew (Suncus murinus), or suncus, is a unique experimental mammal that is cold intolerant. However, even basic knowledge of brown adipose tissue (BAT), which is important for non-shivering thermogenesis (NST), is minimal. Therefore, we exposed suncus for 18 days to mild cold temperatures (8-14 degrees C) and/or a high-fat diet, which are factors that increase NST, and measured two mRNAs that are critical for NST in BAT, uncoupling protein 1 (Ucp1) and type II 5'-deiodinase (D2). Neither mild cold exposure nor a high-fat diet alone induced up-regulation of the mRNAs. However, combinations of cold exposure and high-fat diet significantly increased both mRNAs. Therefore, cold intolerance in suncus may be partly caused by dietary components.
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Affiliation(s)
- Daisuke Suzuki
- Laboratory of Animal Management & Resources, School of Bio-Agricultural Sciences, Department of Teratology and Genetics, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan
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17
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Baumuratov AS, Abzhalelov BB, Kramarova LI, Dolgacheva LP, Zinchenko VP, Bronnikov GE. Cold adaptation modulates Ca2+ signaling in brown preadipocytes. Bull Exp Biol Med 2004. [DOI: 10.1007/bf02694473] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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18
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Masuda Y, Haramizu S, Oki K, Ohnuki K, Watanabe T, Yazawa S, Kawada T, Hashizume SI, Fushiki T. Upregulation of uncoupling proteins by oral administration of capsiate, a nonpungent capsaicin analog. J Appl Physiol (1985) 2003; 95:2408-15. [PMID: 12959953 DOI: 10.1152/japplphysiol.00828.2002] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Capsiate is a nonpungent capsaicin analog, a recently identified principle of the nonpungent red pepper cultivar CH-19 Sweet. In the present study, we report that 2-wk treatment of capsiate increased metabolic rate and promoted fat oxidation at rest, suggesting that capsiate may prevent obesity. To explain these effects, at least in part, we examined uncoupling proteins (UCPs) and thyroid hormones. UCPs and thyroid hormones play important roles in energy expenditure, the maintenance of body weight, and thermoregulation. Two-week treatment of capsiate increased the levels of UCP1 protein and mRNA in brown adipose tissue and UCP2 mRNA in white adipose tissue. This dose of capsiate did not change serum triiodothyronine or thyroxine levels. A single dose of capsiate temporarily raised both UCP1 mRNA in brown adipose tissue and UCP3 mRNA in skeletal muscle. These results suggest that UCP1 and UCP2 may contribute to the promotion of energy metabolism by capsiate, but that thyroid hormones do not.
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Affiliation(s)
- Yoriko Masuda
- Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto Univ., Kyoto 606-8502, Japan
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19
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Shimizu Y, Shimazu T. Thyroid hormone augments GLUT4 expression and insulin-sensitive glucose transport system in differentiating rat brown adipocytes in culture. J Vet Med Sci 2002; 64:677-81. [PMID: 12237511 DOI: 10.1292/jvms.64.677] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effects of triiodothyronine (T3) on differentiation-dependent expression of GLUT and responses of glucose transport to insulin and norepinephrine (NE) were investigated. Precursor cells of brown adipocytes isolated from the interscapular brown adipose tissue of newborn rats were cultured in the absence or presence of various concentrations of T3. Western bolt analysis revealed that treatment with T3 resulted in an increased expression of GLUT4, in a dose-dependent manner, whereas GLUT1 contents were unchanged. In parallel with the increase in GLUT4 expression, T3 improved insulin sensitivity for glucose transport, being accompanied by an increase in maximal transport rate and a reduction of ED(50). In contrast, T3-treatment of the brown adipocytes during the differentiation process had little effect on NE-regulatable glucose transport system. These results suggest that T3 plays a predominant role in the development of insulin-sensitive glucose transport during differentiation of brown adipocytes.
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Affiliation(s)
- Yasutake Shimizu
- Department of Medical Biochemistry, Ehime University School of Medicine, Shigenobu, Japan
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20
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Asano A, Irie Y, Saito M. Isoform-specific regulation of vascular endothelial growth factor (VEGF) family mRNA expression in cultured mouse brown adipocytes. Mol Cell Endocrinol 2001; 174:71-6. [PMID: 11306173 DOI: 10.1016/s0303-7207(00)00450-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We have shown that brown adipose tissue (BAT), a thermogenic organ in mammals, expresses high levels of vascular endothelial growth factor (VEGF) mRNA in response to exposure to cold, which may contribute to angiogenesis associated with cold-induced hyperplasia of this tissue. In the present study, we examined mRNA expression of not only VEGF, but also VEGF-B and VEGF-C, recently cloned VEGF isoforms, in vitro using immortal brown adipocytes (HB2) isolated from mouse BAT. HB2 preadipocytes expressed detectable levels of VEGF, VEGF-B and VEGF-C mRNA, but a low level of VEGF. After HB2 cells differentiated into adipocytes, the VEGF mRNA level increased without a noticeable change in the VEGF-B and VEGF-C mRNA levels. When HB2 cells were stimulated by norepinephrine, the VEGF mRNA level increased without a change in that of VEGF-B, while the VEGF-C mRNA level decreased. A marked reduction of VEGF-C mRNA expression was also found when HB2 cells were treated with agonists of peroxisome proliferator-activated receptor gamma (PPARgamma, troglitazone), retinoic acid receptor (RAR, all-trans retinoic acid) and retinoid X receptor (RXR, 9-cis retinoic acid). These results suggest a specific adrenergic mechanism for up-regulation of VEGF expression different from those for other VEGF isoforms, and thereby the major contribution of VEGF to the cold-induced angiogenesis in BAT. In addition, the agonists of PPARgamma, RAR and RXR are suggested to be inhibitory to angiogenesis through the reduction of VEGF-C production.
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Affiliation(s)
- A Asano
- Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, 060-0818, Sapporo, Japan.
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21
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Subramanian S, Vollmer RR. Depletion of brown fat norepinephrine content by acute cold exposure and adrenoceptor blockade. Pharmacol Biochem Behav 2001; 68:597-602. [PMID: 11325417 DOI: 10.1016/s0091-3057(01)00457-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Experiments were conducted to characterize the effects of acute cold exposure, with and without adrenoceptor blockade, on intrascapular brown adipose tissue (IBAT) and adrenal catecholamine content in male Sprague-Dawley rats. Groups of animals with indwelling temperature transmitters were tested following treatment with saline, the alpha-adrenoceptor blocker phentolamine, the beta-adrenoceptor blocker propranolol, combined blockade with phentolamine plus propranolol, and the ganglionic blocker chlorisondamine. IBAT norepinephrine (NE) content was not affected in animals tested at 22 degrees C, but was reduced in 4 degrees C-exposed animals treated with phentolamine (-57%), phentolamine plus propranolol (-97%), and chlorisondamine (-42%). Adrenal NE and epinephrine (EPI) content were not altered by the treatments at 4 degrees C or 22 degrees C. None of the treatments affected the temperature of animals at 22 degrees C, but significant hypothermia occurred at 4 degrees C after chlorisondamine (-2.3+/-0.3 degrees C) and the combination of phentolamine and propranolol (-1.5+/-0.4 degrees C). These results suggest that cold exposure alone did not affect IBAT NE content, but when cold exposure was combined with adrenoceptor blockade, the sympathetic activation was sufficient to cause a reduction in IBAT NE content. In addition, alpha- and beta-adrenoceptor-mediated mechanisms contribute to the maintenance of core temperature. However, both alpha- and beta-receptor mechanisms had to be interrupted before a deficit in body temperature was detected.
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Affiliation(s)
- S Subramanian
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pittsburgh, PA 15261, USA
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22
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Abstract
In rats and mice the adipose organ consists of several subcutaneous and visceral depots. Some areas of these depots are brown and correspond to brown adipose tissue, while most are white and correspond to white adipose tissue. The number of brown adipocytes found in white areas varies with age, strain and environmental conditions. Brown and white adipocyte precursors are morphologically dissimilar. Together with a rich vascular supply, brown areas receive abundant noradrenergic parenchymal innervation. The gross anatomy and histology of the organ vary considerably in different physiological (cold acclimation, warm acclimation, fasting, lactation) and pathological (obesity) conditions, and many important genes, such as leptin and uncoupling protein 1, are also expressed differently in the two cell types. These basic mechanisms should be taken into account when addressing the physiopathology of obesity and its treatment.
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Affiliation(s)
- S Cinti
- Institute of Normal Human Morphology-Anatomy, School of Medicine, University of Ancona, Italy
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23
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Tsuboyama-Kasaoka N, Tsunoda N, Maruyama K, Takahashi M, Kim H, Cooke DW, Lane MD, Ezaki O. Overexpression of GLUT4 in mice causes up-regulation of UCP3 mRNA in skeletal muscle. Biochem Biophys Res Commun 1999; 258:187-93. [PMID: 10222258 DOI: 10.1006/bbrc.1999.0617] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mitochondrial uncoupling protein 3 (UCP3) is expressed in skeletal muscles. We have hypothesized that increased glucose flux in skeletal muscles may lead to increased UCP3 expression. Male transgenic mice harboring insulin-responsive glucose transporter (GLUT4) minigenes with differing lengths of 5'-flanking sequence (-3237, -2000, -1000 and -442 bp) express different levels of GLUT4 protein in various skeletal muscles. Expression of the GLUT4 transgenes caused an increase in UCP3 mRNA that paralleled the increase of GLUT4 protein in gastrocnemius muscle. The effects of increased intracellular GLUT4 level on the expression of UCP1, UCP2 and UCP3 were compared in several tissues of male 4 month-old mice harboring the -1000 GLUT4 minigene transgene. In the -1000 GLUT4 transgenic mice, expression of GLUT4 mRNA and protein in skeletal muscles, brown adipose tissue (BAT), and white adipose tissue (WAT) was increased by 1.4 to 4.0-fold. Compared with non-transgenic littermates, the -1000 GLUT4 mice exhibited about 4- and 1.8-fold increases of UCP3 mRNA in skeletal muscle and WAT, respectively, and a 38% decrease of UCP1 mRNA in BAT. The transgenic mice had a 16% increase in oxygen consumption and a 14% decrease in blood glucose and a 68% increase in blood lactate, but no change in FFA or beta-OHB levels. T3 and leptin concentrations were decreased in transgenic mice. Expression of UCP1 in BAT of the -442 GLUT4 mice, which did not overexpress GLUT4 in this tissue, was not altered. These findings indicate that overexpression of GLUT4 up-regulates UCP3 expression in skeletal muscle and down-regulates UCP1 expression in BAT, possibly by increasing the rate of glucose uptake into these tissues.
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Affiliation(s)
- N Tsuboyama-Kasaoka
- Division of Clinical Nutrition, National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8636, Japan
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24
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Asano A, Kimura K, Saito M. Cold-induced mRNA expression of angiogenic factors in rat brown adipose tissue. J Vet Med Sci 1999; 61:403-9. [PMID: 10342292 DOI: 10.1292/jvms.61.403] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Brown adipose tissue (BAT) is the major site of non-shivering thermogenesis in rodents. Rapid angiogenesis is induced in association with adaptive hyperplasia of this tissue when the animal is exposed to cold. We demonstrated previously adrenergic activation of mRNA expression of vascular endothelial growth factor (VEGF) in rat BAT and its possible contribution to the cold-induced angiogenesis in this tissue. In the present study, we examined the effect of cold exposure on mRNA expression of other two angiogenic factors, VEGF-B and basic fibroblast growth factor (bFGF), in rats. Conventional Northern blot analysis revealed abundant mRNA expression of VEGF-B as well as VEGF, but not bFGF, in BAT. When rats were exposed to cold at 4 degrees C, the VEGF mRNA level was increased by 2.7-fold in 1-4 hr and returned to the basal level within 24 hr. In contrast, the VEGF-B mRNA level did not change throughout the course of cold exposure. A significant expression of bFGF mRNA was detected in BAT by reverse transcription-polymerase chain reaction (RT-PCR). To evaluate the tissue bFGF mRNA level quantitatively, a competitive RT-PCR method was developed using a shorter RNA fragment as a competitor. The bFGF mRNA level in BAT was found to increase by 2.3-fold in 4 hr and decreased to the basal level within 24 hr after cold exposure. These results suggest that cold exposure leads to induce VEGF and bFGF rapidly and transiently in BAT, which in turn stimulate the proliferation of vascular endothelial cells in this tissue.
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Affiliation(s)
- A Asano
- Department of Biomedical Sciences, School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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25
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Oi Y, Kawada T, Shishido C, Wada K, Kominato Y, Nishimura S, Ariga T, Iwai K. Allyl-containing sulfides in garlic increase uncoupling protein content in brown adipose tissue, and noradrenaline and adrenaline secretion in rats. J Nutr 1999; 129:336-42. [PMID: 10024610 DOI: 10.1093/jn/129.2.336] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The effects of garlic supplementation on triglyceride metabolism were investigated by measurements of the degree of thermogenesis in interscapular brown adipose tissue (IBAT), and noradrenaline and adrenaline secretion in rats fed two types of dietary fat. In Experiment 1, rats were given isoenergetic high-fat diets containing either shortening or lard with or without garlic powder supplementation (8 g/kg of diet). After 28 d feeding, body weight, plasma triglyceride levels and the weights of perirenal adipose tissue and epididymal fat pad were significantly lower in rats fed diets supplemented with garlic powder than in those fed diets without garlic powder. The content of mitochondrial protein and uncoupling protein (UCP) in IBAT, and urinary noradrenaline and adrenaline excretion were significantly greater in rats fed a lard diet with garlic powder than in those fed the same diet without garlic. Other than adrenaline secretion, differences due to garlic were significant in rats fed shortening, also. In Experiment 2, the effects of various allyl-containing sulfides present in garlic on noradrenaline and adrenaline secretion were evaluated. Administration of diallyldisulfide, diallyltrisulfide and alliin, organosulfur compounds present in garlic, significantly increased plasma noradrenaline and adrenaline concentrations, whereas the administration of disulfides without allyl residues, diallylmonosulfide and S-allyl-L-cysteine did not increase adrenaline secretion. These results suggest that in rats, allyl-containing sulfides in garlic enhance thermogenesis by increasing UCP content in IBAT, and noradrenaline and adrenaline secretion.
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Affiliation(s)
- Y Oi
- Laboratory of Nutrition Chemistry, Faculty of Home Economics, Kobe Women's University, Suma-ku, Kobe 654-8585, Japan
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26
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Yoshida T, Umekawa T, Kumamoto K, Sakane N, Kogure A, Kondo M, Wakabayashi Y, Kawada T, Nagase I, Saito M. beta 3-Adrenergic agonist induces a functionally active uncoupling protein in fat and slow-twitch muscle fibers. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:E469-75. [PMID: 9530130 DOI: 10.1152/ajpendo.1998.274.3.e469] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The mitochondrial uncoupling protein (UCP) has usually been found only in brown adipose tissue. We recently observed that a chronic administration of the beta 3-adrenergic agonist CL-316,243 (CL) induced the ectopic expression of UCP in white fat and skeletal muscle in genetic obese yellow KK mice. The aim of the present study was to examine whether UCP could be induced in nongenetic obese animals produced by neonatal injections of monosodium L-glutamate (MSG). The daily subcutaneous injection of CL (0.1 mg/kg) to MSG-induced obese mice for 2 wk caused significant reductions of body weight (15%) and white fat pad weight (58%). Northern and Western blot analyses showed that CL induced significant expressions of UCP in the white fat and muscle, as well as in brown fat. Immunohistochemical observations revealed that the UCP stains in white fat were localized on multilocular cells and that those in muscle were localized on slow-twitch fibers rich in mitochondria. Immunoelectron microscopy confirmed the mitochondrial localization of UCP in the myocytes. The guanosine 5'-diphosphate (GDP) binding to mitochondria in brown fat doubled after the CL treatment. Moreover, significant GDP binding was detected in the white fat and muscle of the CL-treated mice, at about one-fourth and one-thirteenth the activity of brown fat, respectively, suggesting that ectopically expressed UCP is functionally active. We concluded that the beta 3-adrenergic agonist CL can induce functionally active UCP in white fat and slow-twitch muscle fibers of obese mice.
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MESH Headings
- Adipose Tissue/drug effects
- Adipose Tissue/metabolism
- Adrenergic beta-Agonists/pharmacology
- Animals
- Carrier Proteins/biosynthesis
- Carrier Proteins/genetics
- Dioxoles/pharmacology
- Female
- Food Additives/pharmacology
- Guanosine Diphosphate/metabolism
- Ion Channels
- Membrane Proteins/biosynthesis
- Membrane Proteins/genetics
- Mice
- Mice, Obese
- Microscopy, Immunoelectron
- Mitochondria, Muscle/drug effects
- Mitochondria, Muscle/metabolism
- Mitochondrial Proteins
- Muscle Fibers, Slow-Twitch/drug effects
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Obesity/metabolism
- RNA, Messenger/metabolism
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/metabolism
- Receptors, Adrenergic, beta-3
- Sodium Glutamate/pharmacology
- Uncoupling Protein 1
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Affiliation(s)
- T Yoshida
- First Department of Internal Medicine, Kyoto Prefectural University of Medicine, Japan
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27
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Asano A, Morimatsu M, Nikami H, Yoshida T, Saito M. Adrenergic activation of vascular endothelial growth factor mRNA expression in rat brown adipose tissue: implication in cold-induced angiogenesis. Biochem J 1997; 328 ( Pt 1):179-83. [PMID: 9359850 PMCID: PMC1218903 DOI: 10.1042/bj3280179] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cold exposure produces adaptive hyperplasia and growth of brown adipose tissue (BAT), the major site of non-shivering thermogenesis in rodents, associated with increased angiogenesis in this tissue. Vascular endothelial growth factor (VEGF), one of the most potent angiogenic factors, was found to be expressed abundantly in BAT of the rat. When rats were exposed to cold at 4 degrees C, the VEGF mRNA level in BAT was increased by 2-3-fold in 1-4 h, but returned to the basal level within 24 h. VEGF expression in other tissues such as heart, kidney and lung did not change after cold exposure. The cold-induced increase in VEGF mRNA was abolished by surgical sympathetic denervation, but mimicked by administration of noradrenaline or a beta3-adrenoceptor agonist CL316,243, indicating the critical role of the beta-adrenergic pathway in VEGF expression in BAT. Among three isoforms of VEGF, the mRNA of a short form (VEGF120) lacking heparin-binding activity was preferentially increased after cold exposure and treatment with the adrenergic agonists. These results suggest that cold exposure activates the sympathetic nerves and leads to a rapid increase in synthesis of VEGF in BAT, which in turn stimulates the proliferation of surrounding vascular endothelial cells.
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Affiliation(s)
- A Asano
- Department of Biomedical Sciences, School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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Kobayashi M, Nikami H, Morimatsu M, Saito M. Expression and localization of insulin-regulatable glucose transporter (GLUT4) in rat brain. Neurosci Lett 1996; 213:103-6. [PMID: 8858619 DOI: 10.1016/0304-3940(96)12845-7] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The localization of glucose transporters (GLUTs) was examined in various regions of the rat brain. The mRNA of GLUT1 and GLUT3 were found ubiquitously in every brain region (cortex, hippocampus, midbrain, striatum, hypothalamus, medulla oblongata and cerebellum). The mRNA and protein of GLUT4, an insulin-regulatable glucose transporter in peripheral tissues, were also identified, particularly abundantly in the cerebellum. In situ hybridization analysis revealed that GLUT4 mRNA was present in some discrete cells, such as Purkinje cells in the cerebellum, the vestibular nucleus in the medulla oblongata and also in ependymal cells along the cerebral ventricles. The GLUT4 mRNA level in the cerebellum changed little in fasted or experimentally induced diabetic rats while those in adipose tissues decreased much. The results suggest that insulin-sensitive glucose uptake may occur in some specific cells of the brain but is regulated in a different manner from those in peripheral cells.
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Affiliation(s)
- M Kobayashi
- Department of Biomedical Sciences, School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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29
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Nagase I, Yoshida T, Kumamoto K, Umekawa T, Sakane N, Nikami H, Kawada T, Saito M. Expression of uncoupling protein in skeletal muscle and white fat of obese mice treated with thermogenic beta 3-adrenergic agonist. J Clin Invest 1996; 97:2898-904. [PMID: 8675704 PMCID: PMC507386 DOI: 10.1172/jci118748] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The mitochondrial uncoupling protein (UCP) is usually expressed only in brown adipose tissue (BAT) and a key molecule for metabolic thermogenesis. The effects of a highly selective beta 3-adrenergic agonist, CL316,243 (CL), on UCP expression in skeletal muscle and adipose tissues were examined in mice. Daily injection of CL (0.1 mg/kg, sc) to obese yellow KK mice for two weeks caused a significant reduction of body weight, associated with a marked decrease of white fat pad weight and hypertrophy of the interscapular BAT with a sixfold increase in UCP content. Clear signals of UCP protein and mRNA were detected by Western and Northern blot analyses in inguinal, mesenteric and retroperitoneal white fat pads, and also in gastrocnemius and quadriceps muscles, whereas no signal in saline-treated mice. The presence of UCP mRNA in muscle tissues was also confirmed by reverse transcription-PCR analysis. Weaker UCP signals were also detected in control C57BL mice treated with CL, but only in inguinal and retroperitoneal fat pads. Immunohistochemical examinations revealed that UCP stains in the white fat pads were localized on multilocular cells quite similar to typical brown adipocyte, and those in the muscle tissues on myocytes. The mitochondrial localization of UCP in myocytes was confirmed by immunoelectron microscopy. In addition to UCP protein, UCP mRNA was also detected in myocytes by in situ hybridization analysis. Thus, chronic stimulation of the beta 3-adrenergic receptor induces ectopic expression of UCP in adipose tissues conventionally considered as white fat and even in skeletal muscle, which probably contributes to the potent anti-obesity effect of the beta 3-adrenergic agonist.
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Affiliation(s)
- I Nagase
- Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo
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Yoshida T, Umekawa T, Wakabayashi Y, Yoshimoto K, Sakane N, Kondo M. Anti-obesity and anti-diabetic effects of mazindol in yellow KK mice: its activating effect on brown adipose tissue thermogenesis. Clin Exp Pharmacol Physiol 1996; 23:476-82. [PMID: 8800569 DOI: 10.1111/j.1440-1681.1996.tb02764.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
1. The anti-obesity and anti-diabetic effects of mazindol were evaluated in obese diabetic yellow KK mice and C57Bl control mice. 2. The study compound was fed through a gastric tube at a rate of 1 or 2 mg/kg per day (0.01 mol/L HCl as control) for 2 weeks. The following parameters were compared in treated and control animals: bodyweight, food intake, white adipose tissue (WAT) weight, brown adipose tissue (BAT) weight and its thermogenesis, noradrenaline (NA) turnover, blood glucose and serum insulin levels and glucose transporter 4 (GLUT4). 3. Furthermore, bodyweight loss of mice pair-fed the same amount of food as the mazindol-treated mice for 2 weeks was measured. 4. Mazindol significantly decreased food intake and significantly increased guanosine-5'-diphosphate-binding in BAT mitochondria and NA turnover in BAT in both yellow KK and C57Bl groups. The amounts of WAT in subcutaneous, mesenteric and retroperitoneal regions and bodyweights were significantly decreased in both groups. Bodyweight loss in mice pair fed with the mazindol-treated groups was approximately 70% compared with that in the mazindol-treated groups. Furthermore, mazindol decreased the levels of blood glucose and serum insulin during the glucose overloading test in yellow KK mice, but it did not influence the GLUT4 protein concentration in WAT and muscle. 5. These observations suggest that mazindol possesses both an anti-obesity action, due to the inhibition of appetite as well as the activation of BAT thermogenesis via increased NA turnover in BAT, and an anti-diabetic action. Consequently, mazindol may be useful for the treatment of obesity as well as non-insulin-dependent diabetes mellitus in obese persons.
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Affiliation(s)
- T Yoshida
- First Department of Internal Medicine, Kyoto Prefectural University of Medicine, Japan
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