Mammalian Thermogenesis
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Mammalian Thermogenesis
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Author : Lucien Girardier
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Mammalian Thermogenesis written by Lucien Girardier and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
an attempt to rationalize these terminological and conceptual difficulties we have considered the origins of mammalian heat production from two different points of view. The scheme depicted in Fig. 1. 1 illustrates the fate of energy in the body as seen by the nutritionist. After allowing for losses of energy in faeces and urine, the metabolizable energy obtained from food is utilized for main taining and increasing body energy content (maintenance, external work, growth and production). The transformation of metabolizable energy into these forms of net energy also involves inevitable energy losses in the form of heat - thermic energy. Similarly, maintaining homeothermy in cold en vironments involves shivering and non-shivering thermogenesis (NST) and the energy costs of assimilating nutrients and retaining net energy results in obligatory heat losses due to diet-induced thermogenesis (DIT). This obligatory DIT is mainly due to the energy cost of protein and fat synthesis but, in addition to this, there is an adaptive component of DIT that helps maintain body energy content (i. e. body weight) by dissipating the metabolizable energy consumed in excess of the requirements for maintenance, growth and production. In Fig. 1. 2, we have converted this nutritionist's scheme (A) into one that A B r-------. . . , I I Production, Growth I I External work I I I I Essential energy expenditure NET BASAL Obligatory 1 I ENERGY Maintenance HEAT heat I FASTING at (BMR) productlpn for t ROC thermoneutrallty homeothermia r.
The Evolution Of Endothermy From Patterns To Mechanisms
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Author : Elias T. Polymeropoulos
language : en
Publisher: Frontiers Media SA
Release Date : 2018-09-14
The Evolution Of Endothermy From Patterns To Mechanisms written by Elias T. Polymeropoulos and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-09-14 with categories.
Metabolic rate is a key ecophysiological factor determining fitness, distribution, survival and reproductive strategies of organisms. The ability to endogenously produce heat and elevate body temperature beyond ambient, has far reaching ecological implications. The diversity of thermogenic mechanisms and strategies employed throughout the animal kingdom is truly phenomenal and one of the greatest biological mysteries. Interestingly, even heat producing plants have been characterised. Over the last several decades, the oversimplified distinction between warm- and cold blooded animals has well and truly been put to rest and the terms “endo- and ectotherm” have been established. Birds and mammals are regarded as endotherms, capable of maintaining high body temperatures within highly precise boundaries. On contrary, in ectothermic organisms ambient temperature governs body temperature and metabolism, encompassing the majority of present day species. However, it has recently become very clear that this distinction is still not accurate enough to describe the vastness of heat generating mechanisms within endo- but also ectotherms. Indeed, a plethora of ectothermic animals display endogenous as well as behavioural means of temperature control and mechanisms for heat generation. There is large diversity in regards to thermoregulatory ability and strategy within endotherms as well, with some groups being classified by separate categories such as basoendotherms and mesotherms. Considerable interest and efforts has been put into the quest to understand the underlying physiological mechanisms leading and facilitating high metabolic rates and body temperatures of endotherms. These mechanisms are far from being exhaustively studied and the evolutionary trajectory leading to high metabolic rates and stable body temperatures is equally, vividly debated. This discussion includes an array of questions and theories surrounding the presence of endothermy in extinct dinosaurs. In addition, a lively debate surrounds the evolutionary drivers promoting the establishment of endothermy with clear support of direct or indirect selective benefits. Within this Research Topic we plan to compile the latest ideas, knowledge and experimental work to elucidate the patterns of the evolution of endothermy and its transition/distinction from ectothermy. The focus is on key physiological mechanisms supporting this transition and contributing to the maintenance of high metabolic rates and body temperature in endotherms, as well as mechanisms for local heterothermy and heat dissipation in ectotherms. These mechanisms and conclusions may be derived from different levels of organisation such as population, taxon, species as well as tissue, cellular or molecular levels. It may also encompass novel experimental or theoretical models testing evolutionary theories of endothermy. A comparative approach is encouraged but not fundamental.
Defining The Mechanisms Of Uncoupling Protein 3 Induced Thermogenesis And Metabolism In Brown Adipose Tissue
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Author : Sonya Maria Veron
language : en
Publisher:
Release Date : 2014
Defining The Mechanisms Of Uncoupling Protein 3 Induced Thermogenesis And Metabolism In Brown Adipose Tissue written by Sonya Maria Veron and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Uncoupling proteins (UCPs) constitute a highly conserved subset of mitochondrial solute carriers. Discovered in small rodents in the early 1970's, UCPs and their homologs have since been found in nematodes, plants, birds, and, most recently, in significant depots within humans (Krauss et al. 2005, Van marken Lichtenbelt 2009). Following activation by long chain fatty acids (LCFA, e.g. oleic acid) and reactive oxygen species (ROS, e.g. 4-hydroxynonenal (4HNE)), UCPs form a proton channel within the inner mitochondrial membrane and permit the influx of hydrogen ions from the inter membrane space into the mitochondrial matrix. UCPs effectively uncouple oxidative phosphorylation (OX-PHOS) from ATP generation, resulting in increasing oxygen consumption and dissipating the chemical energy in the form of heat. Found primarily in brown adipose tissue (BAT) of small hibernating mammals, the canonical role of uncoupling protein 1 (UCP1) in mammalian adaptive thermogenesis has been thoroughly studied. However, UCP1 is not the only member of the uncoupling family found within BAT. Also playing a key role in this tissue is uncoupling protein 3 (UCP3), which is a close homolog to UCP1. However, in spite of the fact that UCP3 shares more than 50% amino acid homology and tissue localization with UCP1, the true function UCP3 is very poorly elucidated. Part of the difficulty in determining this function lies in the expression levels of the UCP3 protein, which are hundreds of folds less than UCP1 in this tissue. In addition, their homologous structure makes teasing apart UCP3-specific phenomena from UCP1-mediated mechanisms very difficult using conventional techniques in cell and molecular biology. While UCP1 is almost exclusively found in BAT, UCP3 is expressed primarily in skeletal muscle (SKM), which lacks UCP1 completely (Krauss et al. 2005). Because UCP3 is so enriched in SKM, many studies have focused on its role in that tissue and have then tried to transpose these functions into BAT. As a result, UCP3 has been implicated in facilitating numerous biological processes, including non-adaptive facultative thermogenesis, affecting SKM oxidative capacity by modulating LCFA export, and ameliorating elevated levels of ROS-mediated stress within the tissue via glutathionine (GSH) interacting moieties. Ultimately, however, little consensus exists on the function of UCP3 within SKM, and subsequently, even less is known about its purpose in BAT. Previous data has shown that murine UCP1 has the capacity to bind to itself and form homo-tetramers when expressed in vitro in recombinant E. coli (Hoang T. et al. 2013). Here we show that UCP1 interacts with UCP3 in BAT in vivo, supporting Hoang's research above by showing that UCP1 has the capacity to not only homodimerize but potentially oligomerize with other UCP homologs. While many groups using UCP3-null mice have reported no gross changes in physiologic responses, data previously published in the lab showed that mice lacking UCP3 were protected from potentially fatal hyperthermic effects when administered sympathomimetic agents such as 3,4-Methylenedioxymethamphetamine (MDMA), methamphetamine (METH), lipopolysaccharide (LPS), or norepinephrine (NE) (Mills et al. 2003, Kenaston et al. 2010). This implies that UCP3 plays an intimate role in sympathetic nervous system (SNS) mediated thermogenesis. Based upon the foregoing, the primary goal of the research discussed in this thesis was to elucidate the functions of UCP3 within BAT. In this study, we recapitulated results seen by other students in this lab: that global UCP3-null mice do indeed exhibit a blunted thermogenic response when treated with sympathomimetic agonists. In addition, despite the near-ubiquitous expression of UCP2 throughout the mammalian organism, this UCP is not involved in SNS-mediated thermogenesis (Arsenijevic et al. 2000). Our data shows that UCP3 is vital to the catecholamine-mediated thermogenic responses following sympathomimetic drug administration. When challenged by METH, UCP3-null mice were able to respond, albeit with a blunted increase in body temperature. Furthermore, when challenged by NE, a key neurotransmitter involved in mediating the responses initiated by the SNS following METH exposure, UCP3-null mice were able to mount half the hyperthermic response seen in WT littermates. However, UCP1/UCP3 double-null animals exhibited an almost four-fold hypothermic effect compared to WT littermates when challenged with NE. In addition, UCP1/UCP3 double-null mice were unable to restore body temperatures back to baseline values, an effect seen in all the other genotypes. This implies that UCP3 plays an important role in restoring body temperatures to physiological norms. Therefore, while the mechanism underlying the decreased responsiveness to NE remains unclear, it is clear that whether localized to SKM or BAT, UCP3 is a major player in the mammalian response to SNS-mediated thermogenesis and global thermoregulation.
Thermogenesis
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Author :
language : en
Publisher:
Release Date : 1990
Thermogenesis written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with categories.
Shivering Thermogenesis In Birds
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Author : Esa Hohtola
language : en
Publisher:
Release Date : 1982
Shivering Thermogenesis In Birds written by Esa Hohtola and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1982 with Animal heat categories.
The mechanism, control, evolution and electromyographic correlates.
Temperature Regulation In Humans And Other Mammals
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Author : Claus Jessen
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Temperature Regulation In Humans And Other Mammals written by Claus Jessen and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
How do mammals manage to maintain their body temperature within the same narrow range in environments as different as polar regions and hot deserts? This advanced text describes the morphological features and physiological mechanisms by which humans and other mammals maintain their body temperature within a narrow range despite large variations in climatic conditions and internal heat production. Its 19 chapters deal with the physics of heat exchange with the environment, and the autonomic and behavioural mechanisms available to control the loss and production of heat. The neuronal basis of temperature regulation and current concepts of the central nervous interface between temperature signals generated in the body and control mechanisms are examined in detail. This book is of invaluable help for undergraduates, postgraduates, teachers, physicians and scientists.
Effectors Of Thermogenesis
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Author : Girardier
language : en
Publisher: Birkhäuser
Release Date : 2013-11-22
Effectors Of Thermogenesis written by Girardier and has been published by Birkhäuser this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-11-22 with Science categories.
One of the most interesting aspects of thermogenesis research is that it quite naturally attracts workers from an extremely wide spectrum of interests, ranging from the mechanism of cellular respiratory control at the molecular level and neuro-hormonal control of energy dissipation both at the cellular level and that of the whole organisms to the mechanism of temperature control during the hibernating cycle and that of cold acclimatation. Thus, the Satellite Symposium on "The Effectors of Thermogenesis" brought together not only physiologists, but also biochemists, pharmacologists, zoologists and clinicians, and provided a forum for the airing of new ideas as well as for the confrontation of different points of view. These are now reproduced in this book in exactly the same form and order in which they were presented at the Symposium, in the hope of providing a bird's-eye view of the various facets of thermogenesis research. A "mini-review", summarizing the current knowledge in each domain, therefore precedes the corresponding papers. The editors are deeply indebted to the contributors of these introductory lectures for so competently selecting from the mass of available information in each field, only the most essential elements. This book is dedicated to Dr. Robert Emrie Smith, a pioneer and path-finder in this field, who organized the first meeting on thermogenesis as a satellite of the XXI International Congress of Physiological Sciences and took an active part in the four subsequent meetings. L. Girardier DEDICATION Dr.
Temperature Regulation In Mammals And Other Vertebrates
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Author : J. Bligh
language : en
Publisher:
Release Date : 1973
Temperature Regulation In Mammals And Other Vertebrates written by J. Bligh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1973 with Nature categories.
A comprehensive analysis of the evolutionary progression and the physiology of temperature regulation in vertebrates.
Strategies In Cold
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Author : Lawrence C.H. Wang
language : en
Publisher: Elsevier
Release Date : 2012-12-02
Strategies In Cold written by Lawrence C.H. Wang and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-02 with Nature categories.
Strategies in Cold: Natural Torpidity and Thermogenesis is a collection of review papers presented at the Fifth International Symposium on Mammalian Hibernation, held at Jasper Park Lodge, Alberta, Canada on October 3-8, 1977. The book is organized into four sections encompassing 20 chapters that cover the advances made since the 1971 symposium in the areas of molecular, biochemical, and cellular adaptations of natural torpidity and the role of the central nervous system in regulation of natural torpidity. The opening section discusses the possible ways of generating circannual cycle in constant condition and the historical progress in understanding the mechanism of shallow, daily torpor and its distribution in various families predominantly from the marsupial, insectivore, and rodent orders. The application of simple economic models to biological systems to illustrate the principles of torpor in non-mammalian organisms and temperature regulation is also described in this text. Section II examines the central nervous structures involved in thermoregulation in hibernators and compares these data with the results of corresponding experiments in non-hibernators. Topics on the influence of serotonergic pathways in the brain on hypothalamic hormonal factor release and the maintenance and regulation of hibernation through a parasympathetic response are discussed in this section. Section III deals with the cellular and biochemical adaptations in natural torpidity, with an emphasis on the metabolic and endocrine changes in hibernation. Section IV tackles postulated mechanisms for nonshivering thermogenesis and the neurohumoral factors regulating these mechanisms in mammals exposed to short-term as well as to prolonged periods of cold. A discussion on significance and possible central mechanisms of thermoregulatory threshold deviations in the course of thermal adaptation is also provided.
Animal Models For The Study Of Human Disease
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Author : Belinda A. Henry
language : en
Publisher: Elsevier Inc. Chapters
Release Date : 2013-05-29
Animal Models For The Study Of Human Disease written by Belinda A. Henry and has been published by Elsevier Inc. Chapters this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-05-29 with Medical categories.
Body weight is determined by the balance between energy intake and energy expenditure. Obesity ensues when energy intake exceeds that of energy expenditure. To date, the majority of pharmaco-therapies to control body weight have been directed towards the appetitive limb of this energy balance equation. Very few anti-obesity agents target the manipulation of energy expenditure. The recent unequivocal demonstration that functional brown adipose tissue is present in adult humans has sparked a great deal of interest in developing means to exploit thermogenesis to control body weight. Thermogenesis is defined as the dissipation of energy through the production of heat and occurs in specialised tissues including brown adipose tissue and skeletal muscle. This chapter will highlight a number of animal models that are currently utilised in effort to understand the mechanisms that underpin thermogenesis. It will describe the control of thermogenesis in skeletal muscle and adipose tissue as well as detailing the role of thermogenesis in determining the susceptibility to obesity in a number of distinct animal models.