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Kelly L Drew - One of the best experts on this subject based on the ideXlab platform.
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the raphe pallidus and the hypothalamic pituitary thyroid axis gate seasonal changes in thermoregulation in the hibernating arctic ground squirrel urocitellus parryii
Frontiers in Physiology, 2018Co-Authors: Carla Frare, Mackenzie Jenkins, Steven J Soldin, Kelly L DrewAbstract:Thermoregulation is necessary to maintain energy homeostasis. The novel discovery of brown adipose tissue (BAT) in humans has increased research interests in better understanding BAT Thermogenesis to restore energy balance in metabolic disorders. The hibernating Arctic ground squirrel (AGS) offers a novel approach to investigate BAT Thermogenesis. AGS seasonally increase their BAT mass to increase the ability to generate heat during interbout arousals. The mechanisms promoting the seasonal changes in BAT Thermogenesis are not well understood. BAT Thermogenesis is regulated by the raphe pallidus (rPA) and by thyroid hormones produced by the hypothalamic-pituitary-thyroid (HPT) axis. Here, we investigate if the HPT axis and the rPA undergo seasonal changes to modulate BAT Thermogenesis in hibernation. We used histological analysis and tandem mass spectrometry to assess activation of the HPT axis and immunohistochemistry to measure neuronal activation. We found an increase in HPT axis activation in fall and in response to pharmacologically induced torpor when adenosine A1 receptor agonist was administered in winter. By contrast, the rPA neuronal activation was lower in winter in response to pharmacologically induced torpor. Activation of the rPA was also lower in winter compared to the other seasons. Our results suggest that thermogenic capacity develops during fall as the HPT axis is activated to reach maximum capacity in winter seen by increased free thyroid hormones in response to cooling. However, Thermogenesis is inhibited during torpor as sympathetic premotor neuronal activation is lower in winter, until arousal when inhibition of Thermogenesis is relieved. These findings describe seasonal modulation of thermoregulation that conserves energy through attenuated sympathetic drive, but retains heat generating capacity through activation of the HPT axis.
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Table_1_The Raphe Pallidus and the Hypothalamic-Pituitary-Thyroid Axis Gate Seasonal Changes in Thermoregulation in the Hibernating Arctic Ground Squirrel (Urocitellus parryii).DOCX
2018Co-Authors: Carla Frare, Steven J Soldin, Mackenzie E. Jenkins, Kelly L DrewAbstract:Thermoregulation is necessary to maintain energy homeostasis. The novel discovery of brown adipose tissue (BAT) in humans has increased research interests in better understanding BAT Thermogenesis to restore energy balance in metabolic disorders. The hibernating Arctic ground squirrel (AGS) offers a novel approach to investigate BAT Thermogenesis. AGS seasonally increase their BAT mass to increase the ability to generate heat during interbout arousals. The mechanisms promoting the seasonal changes in BAT Thermogenesis are not well understood. BAT Thermogenesis is regulated by the raphe pallidus (rPA) and by thyroid hormones produced by the hypothalamic–pituitary–thyroid (HPT) axis. Here, we investigate if the HPT axis and the rPA undergo seasonal changes to modulate BAT Thermogenesis in hibernation. We used histological analysis and tandem mass spectrometry to assess activation of the HPT axis and immunohistochemistry to measure neuronal activation. We found an increase in HPT axis activation in fall and in response to pharmacologically induced torpor when adenosine A1 receptor agonist was administered in winter. By contrast, the rPA neuronal activation was lower in winter in response to pharmacologically induced torpor. Activation of the rPA was also lower in winter compared to the other seasons. Our results suggest that thermogenic capacity develops during fall as the HPT axis is activated to reach maximum capacity in winter seen by increased free thyroid hormones in response to cooling. However, Thermogenesis is inhibited during torpor as sympathetic premotor neuronal activation is lower in winter, until arousal when inhibition of Thermogenesis is relieved. These findings describe seasonal modulation of thermoregulation that conserves energy through attenuated sympathetic drive, but retains heat generating capacity through activation of the HPT axis.
Akiyuki Watarai - One of the best experts on this subject based on the ideXlab platform.
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characterization of brown adipose tissue Thermogenesis in the naked mole rat heterocephalus glaber a heterothermic mammal
Scientific Reports, 2020Co-Authors: Yuki Oiwa, Kaori Oka, Hironobu Yasui, Kei Higashikawa, Hidemasa Bono, Yoshimi Kawamura, Shingo Miyawaki, Akiyuki WataraiAbstract:The naked mole-rat (NMR) is a heterothermic mammal that forms eusocial colonies consisting of one reproductive female (queen), several reproductive males, and subordinates. Despite their heterothermy, NMRs possess brown adipose tissue (BAT), which generally induces Thermogenesis in cold and some non-cold environments. Previous studies suggest that NMR-BAT induces Thermogenesis by cold exposure. However, detailed NMR-BAT characteristics and whether NMR-BAT Thermogenesis occurs in non-cold environments are unknown. Here, we show beta-3 adrenergic receptor (ADRB3)-dependent thermogenic potential of NMR-BAT, which contributes to Thermogenesis in the isolated queen in non-cold environments (30 °C). NMR-BAT expressed several brown adipocyte marker genes and showed noradrenaline-dependent thermogenic activity in vitro and in vivo. Although our ADRB3 inhibition experiments revealed that NMR-BAT Thermogenesis slightly delays the decrease in body temperature in a cold environment (20 °C), it was insufficient to prevent the decrease in the body temperatures. Even at 30 °C, NMRs are known to prevent the decrease of and maintain their body temperature by heat-sharing behaviors within the colony. However, isolated NMRs maintained their body temperature at the same level as when they are in the colony. Interestingly, we found that queens, but not subordinates, induce BAT Thermogenesis in this condition. Our research provides novel insights into NMR thermoregulation.
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characterization of brown adipose tissue Thermogenesis in the naked mole rat heterocephalus glaber a poikilothermic mammal
bioRxiv, 2020Co-Authors: Yuki Oiwa, Kaori Oka, Hironobu Yasui, Kei Higashikawa, Hidemasa Bono, Yoshimi Kawamura, Shingo Miyawaki, Akiyuki Watarai, Takefumi Kikusui, Atsushi ShimizuAbstract:The naked mole-rat (NMR) is a poikilothermic mammal that forms eusocial colonies consisting of one breeding queen, several breeding kings, and subordinates. Despite their poikilothermic feature, NMRs possess brown adipose tissue (BAT), which in homeothermic mammals induces Thermogenesis in cold environments. However, NMR-BAT thermogenic potential is controversial, and its physiological roles are unknown. Here, we show that NMR-BAT has beta-3 adrenergic receptor (ADRB3)-dependent thermogenic potential, which contributes to Thermogenesis in the isolated queen in non-cold environments. NMR-BAT expressed several brown adipocyte marker genes and showed noradrenaline-dependent thermogenic activity in vitro and in vivo. Although our ADRB3 inhibition experiments revealed that NMR-BAT Thermogenesis slightly delays the decrease in body temperature in a cold environment, it was insufficient to maintain the body temperatures of the NMRs. In a non-cold environment, NMRs are known to increase their body temperature by a heat-sharing behavior. Interestingly, we found that the body temperatures of NMRs isolated from the colony were also significantly higher than the ambient temperature. We also show that queens, but not subordinates, induce BAT Thermogenesis in isolated, non-cold conditions. Our research provides novel insights into the role and mechanism of thermoregulation in this unique poikilothermic mammal.
Julie Dam - One of the best experts on this subject based on the ideXlab platform.
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a role for the melatonin related receptor gpr50 in leptin signaling adaptive Thermogenesis and torpor
Current Biology, 2012Co-Authors: David A Echtold, Laura E Hand, Anissa Sidibe, E Sae, Elena A Ivanova, Veerle Darras, Julie DamAbstract:The ability of mammals to maintain a constant body temperature has proven to be a profound evolutionary advantage, allowing members of this class to thrive in most environments on earth. Intriguingly, some mammals employ bouts of deep hypothermia (torpor) to cope with reduced food supply and harsh climates [1, 2]. During torpor, physiological processes such as respiration, cardiac function, and metabolic rate are severely depressed, yet the neural mechanisms that regulate torpor remain unclear [3]. Hypothalamic responses to energy signals, such as leptin, influence the expression of torpor [4-7]. We show that the orphan receptor GPR50 plays an important role in adaptive Thermogenesis and torpor. Unlike wild-type mice, Gpr50(-/-) mice readily enter torpor in response to fasting and 2-deoxyglucose administration. Decreased Thermogenesis in Gpr50(-/-) mice is not due to a deficit in brown adipose tissue, the principal site of nonshivering Thermogenesis in mice [8]. GPR50 is highly expressed in the hypothalamus of several species, including man [9, 10]. In line with this, altered thermoregulation in Gpr50(-/-) mice is associated with attenuated responses to leptin and a suppression of thyrotropin-releasing hormone. Thus, our findings identify hypothalamic circuits involved in torpor and reveal GPR50 to be a novel component of adaptive Thermogenesis in mammals.
Christopher J Madden - One of the best experts on this subject based on the ideXlab platform.
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central nervous system regulation of brown adipose tissue
Comprehensive Physiology, 2014Co-Authors: Shaun F Morrison, Christopher J MaddenAbstract:Thermogenesis, the production of heat energy, in brown adipose tissue is a significant component of the homeostatic repertoire to maintain body temperature during the challenge of low environmental temperature in many species from mouse to man and plays a key role in elevating body temperature during the febrile response to infection. The sympathetic neural outflow determining brown adipose tissue (BAT) Thermogenesis is regulated by neural networks in the CNS which increase BAT sympathetic nerve activity in response to cutaneous and deep body thermoreceptor signals. Many behavioral states, including wakefulness, immunologic responses, and stress, are characterized by elevations in core body temperature to which central command-driven BAT activation makes a significant contribution. Since energy consumption during BAT Thermogenesis involves oxidation of lipid and glucose fuel molecules, the CNS network driving cold-defensive and behavioral state-related BAT activation is strongly influenced by signals reflecting the short- and long-term availability of the fuel molecules essential for BAT metabolism and, in turn, the regulation of BAT Thermogenesis in response to metabolic signals can contribute to energy balance, regulation of body adipose stores and glucose utilization. This review summarizes our understanding of the functional organization and neurochemical influences within the CNS networks that modulate the level of BAT sympathetic nerve activity to produce the thermoregulatory and metabolic alterations in BAT Thermogenesis and BAT energy expenditure that contribute to overall energy homeostasis and the autonomic support of behavior. © 2014 American Physiological Society. Compr Physiol 4:1677-1713, 2014.
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autonomic regulation of brown adipose tissue Thermogenesis in health and disease potential clinical applications for altering bat Thermogenesis
Frontiers in Neuroscience, 2014Co-Authors: Domenico Tupone, Christopher J Madden, Shaun F MorrisonAbstract:From mouse to man, brown adipose tissue (BAT) is a significant source of Thermogenesis contributing to the maintenance of the body temperature homeostasis during the challenge of low environmental temperature. In rodents, BAT Thermogenesis also contributes to the febrile increase in core temperature during the immune response. BAT sympathetic nerve activity controlling BAT Thermogenesis is regulated by CNS neural networks which respond reflexively to thermal afferent signals from cutaneous and body core thermoreceptors, as well as to alterations in the discharge of central neurons with intrinsic thermosensitivity. Superimposed on the core thermoregulatory circuit for the activation of BAT Thermogenesis, is the permissive, modulatory influence of central neural networks controlling metabolic aspects of energy homeostasis. The recent confirmation of the presence of BAT in human and its function as an energy consuming organ have stimulated interest in the potential for the pharmacological activation of BAT to reduce adiposity in the obese. In contrast, the inhibition of BAT Thermogenesis could facilitate the induction of therapeutic hypothermia for fever reduction or to improve outcomes in stroke or cardiac ischemia by reducing infarct size through a lowering of metabolic oxygen demand. This review summarizes the central circuits for the autonomic control of BAT Thermogenesis and highlights the potential clinical relevance of the pharmacological inhibition or activation of BAT Thermogenesis.
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Central control of brown adipose tissue Thermogenesis
Frontiers Media S.A., 2012Co-Authors: Shaun F Morrison, Christopher J Madden, Domenico EtuponeAbstract:Thermogenesis, the production of heat energy, is an essential component of the homeostatic repertoire to maintain body temperature during the challenge of low environmental temperature and plays a key role in elevating body temperature during the febrile response to infection. Mitochondrial oxidation in brown adipose tissue (BAT) is a significant source of neurally-regulated metabolic heat production in many species from mouse to man. BAT Thermogenesis is regulated by neural networks in the central nervous system which responds to feedforward afferent signals from cutaneous and core body thermoreceptors and to feedback signals from brain thermosensitive neurons to activate BAT sympathetic nerve activity. This review summarizes the research leading to a model of the feedforward reflex pathway through which environmental cold stimulates BAT Thermogenesis and includes the influence on this thermoregulatory network of the pyrogenic mediator, prostaglandin E2, to increase body temperature during fever. The cold thermal afferent circuit from cutaneous thermal receptors, through second-order thermosensory neurons in the dorsal horn of the spinal cord ascends to activate neurons in the lateral parabrachial nucleus which drive GABAergic interneurons in the preoptic area to inhibit warm-sensitive, inhibitory output neurons of the preoptic area. The resulting disinhibition of BAT Thermogenesis-promoting neurons in the dorsomedial hypothalamus activates BAT sympathetic premotor neurons in the rostral ventromedial medulla, including the rostral raphe pallidus, which provide excitatory, and possibly disinhibitory, inputs to spinal sympathetic circuits to drive BAT Thermogenesis. Other recently recognized central sites influencing BAT Thermogenesis and energy expenditure are also described
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an orexinergic projection from perifornical hypothalamus to raphe pallidus increases rat brown adipose tissue Thermogenesis
The Journal of Neuroscience, 2011Co-Authors: Domenico Tupone, Christopher J Madden, Georgina Cano, Shaun F MorrisonAbstract:Orexin (hypocretin) neurons, located exclusively in the PeF-LH, which includes the perifornical area (PeF), the lateral hypothalamus (LH), and lateral portions of the medial hypothalamus, have widespread projections and influence many physiological functions, including the autonomic regulation of body temperature and energy metabolism. Narcolepsy is characterized by the loss of orexin neurons and by disrupted sleep, but also by dysregulation of body temperature and by a strong tendency for obesity. Heat production (Thermogenesis) in brown adipose tissue (BAT) contributes to the maintenance of body temperature and, through energy consumption, to body weight regulation. We identified a neural substrate for the influence of orexin neurons on BAT Thermogenesis in rat. Nanoinjection of orexin-A (12 pmol) into the rostral raphe pallidus (rRPa), the site of BAT sympathetic premotor neurons, produced large, sustained increases in BAT sympathetic outflow and in BAT Thermogenesis. Activation of neurons in the PeF-LH also enhanced BAT Thermogenesis over a long time course. Combining viral retrograde tracing from BAT, or cholera toxin subunit b tracing from rRPa, with orexin immunohistochemistry revealed synaptic connections to BAT from orexin neurons in PeF-LH and from rRPa neurons with closely apposed, varicose orexin fibers, as well as a direct, orexinergic projection from PeF-LH to rRPa. These results indicate a potent modulation of BAT Thermogenesis by orexin released from the terminals of orexin neurons in PeF-LH directly into the rRPa and provide a potential mechanism contributing to the disrupted regulation of body temperature and energy metabolism in the absence of orexin.
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central control of Thermogenesis in mammals
Experimental Physiology, 2008Co-Authors: Shaun F Morrison, Kazuhiro Nakamura, Christopher J MaddenAbstract:Thermogenesis, the production of heat energy, is an essential component of the homeostatic repertoire to maintain body temperature in mammals and birds during the challenge of low environmental temperature and plays a key role in elevating body temperature during the febrile response to infection. The primary sources of neurally regulated metabolic heat production are mitochondrial oxidation in brown adipose tissue, increases in heart rate and shivering in skeletal muscle. Thermogenesis is regulated in each of these tissues by parallel networks in the central nervous system, which respond to feedforward afferent signals from cutaneous and core body thermoreceptors and to feedback signals from brain thermosensitive neurons to activate the appropriate sympathetic and somatic efferents. This review summarizes the research leading to a model of the feedforward reflex pathway through which environmental cold stimulates Thermogenesis and discusses the influence on this thermoregulatory network of the pyrogenic mediator, prostaglandin E2, to increase body temperature. The cold thermal afferent circuit from cutaneous thermal receptors ascends via second-order thermosensory neurons in the dorsal horn of the spinal cord to activate neurons in the lateral parabrachial nucleus, which drive GABAergic interneurons in the preoptic area to inhibit warm-sensitive, inhibitory output neurons of the preoptic area. The resulting disinhibition of Thermogenesis-promoting neurons in the dorsomedial hypothalamus and possibly of sympathetic and somatic premotor neurons in the rostral ventromedial medulla, including the raphe pallidus, activates excitatory inputs to spinal sympathetic and somatic motor circuits to drive Thermogenesis.
Carla Frare - One of the best experts on this subject based on the ideXlab platform.
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the raphe pallidus and the hypothalamic pituitary thyroid axis gate seasonal changes in thermoregulation in the hibernating arctic ground squirrel urocitellus parryii
Frontiers in Physiology, 2018Co-Authors: Carla Frare, Mackenzie Jenkins, Steven J Soldin, Kelly L DrewAbstract:Thermoregulation is necessary to maintain energy homeostasis. The novel discovery of brown adipose tissue (BAT) in humans has increased research interests in better understanding BAT Thermogenesis to restore energy balance in metabolic disorders. The hibernating Arctic ground squirrel (AGS) offers a novel approach to investigate BAT Thermogenesis. AGS seasonally increase their BAT mass to increase the ability to generate heat during interbout arousals. The mechanisms promoting the seasonal changes in BAT Thermogenesis are not well understood. BAT Thermogenesis is regulated by the raphe pallidus (rPA) and by thyroid hormones produced by the hypothalamic-pituitary-thyroid (HPT) axis. Here, we investigate if the HPT axis and the rPA undergo seasonal changes to modulate BAT Thermogenesis in hibernation. We used histological analysis and tandem mass spectrometry to assess activation of the HPT axis and immunohistochemistry to measure neuronal activation. We found an increase in HPT axis activation in fall and in response to pharmacologically induced torpor when adenosine A1 receptor agonist was administered in winter. By contrast, the rPA neuronal activation was lower in winter in response to pharmacologically induced torpor. Activation of the rPA was also lower in winter compared to the other seasons. Our results suggest that thermogenic capacity develops during fall as the HPT axis is activated to reach maximum capacity in winter seen by increased free thyroid hormones in response to cooling. However, Thermogenesis is inhibited during torpor as sympathetic premotor neuronal activation is lower in winter, until arousal when inhibition of Thermogenesis is relieved. These findings describe seasonal modulation of thermoregulation that conserves energy through attenuated sympathetic drive, but retains heat generating capacity through activation of the HPT axis.
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Table_1_The Raphe Pallidus and the Hypothalamic-Pituitary-Thyroid Axis Gate Seasonal Changes in Thermoregulation in the Hibernating Arctic Ground Squirrel (Urocitellus parryii).DOCX
2018Co-Authors: Carla Frare, Steven J Soldin, Mackenzie E. Jenkins, Kelly L DrewAbstract:Thermoregulation is necessary to maintain energy homeostasis. The novel discovery of brown adipose tissue (BAT) in humans has increased research interests in better understanding BAT Thermogenesis to restore energy balance in metabolic disorders. The hibernating Arctic ground squirrel (AGS) offers a novel approach to investigate BAT Thermogenesis. AGS seasonally increase their BAT mass to increase the ability to generate heat during interbout arousals. The mechanisms promoting the seasonal changes in BAT Thermogenesis are not well understood. BAT Thermogenesis is regulated by the raphe pallidus (rPA) and by thyroid hormones produced by the hypothalamic–pituitary–thyroid (HPT) axis. Here, we investigate if the HPT axis and the rPA undergo seasonal changes to modulate BAT Thermogenesis in hibernation. We used histological analysis and tandem mass spectrometry to assess activation of the HPT axis and immunohistochemistry to measure neuronal activation. We found an increase in HPT axis activation in fall and in response to pharmacologically induced torpor when adenosine A1 receptor agonist was administered in winter. By contrast, the rPA neuronal activation was lower in winter in response to pharmacologically induced torpor. Activation of the rPA was also lower in winter compared to the other seasons. Our results suggest that thermogenic capacity develops during fall as the HPT axis is activated to reach maximum capacity in winter seen by increased free thyroid hormones in response to cooling. However, Thermogenesis is inhibited during torpor as sympathetic premotor neuronal activation is lower in winter, until arousal when inhibition of Thermogenesis is relieved. These findings describe seasonal modulation of thermoregulation that conserves energy through attenuated sympathetic drive, but retains heat generating capacity through activation of the HPT axis.
