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Steiner MA, Toeroek-Schafroth M, Giusepponi ME, Dacome L, Tessari M. Abuse potential assessment of the dual orexin receptor antagonist daridorexant in rats. J Psychopharmacol 2023; 37:1249-1260. [PMID: 38059356 PMCID: PMC10714714 DOI: 10.1177/02698811231215415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
BACKGROUND Drugs that act on the central nervous system (CNS) and have sedative effects can lead to abuse in humans. New CNS-active drugs often require evaluation of their abuse potential in dedicated animal models before marketing approval. Daridorexant is a new dual orexin receptor antagonist (DORA) with sleep-promoting properties in animals and humans. It was approved in 2022 in the United States and Europe for the treatment of insomnia disorder. AIMS Nonclinical evaluation of abuse potential of daridorexant using three specific rat models assessing reinforcement, interoception, and withdrawal. METHODS Reinforcing effects of daridorexant were assessed in an operant rat model of intravenous drug self-administration. Similarity of interoceptive effects to those of the commonly used sleep medication zolpidem was tested in an operant drug discrimination task. Withdrawal signs indicative of physical dependence were evaluated upon sudden termination of chronic daridorexant treatment. Rat experiments were conducted at a dose range resulting in daridorexant plasma concentrations equaling or exceeding those achieved at the clinically recommended dose of 50 mg in humans. RESULTS Daridorexant had no reinforcing effects, was dissimilar to zolpidem in the drug discrimination task, and did not induce any withdrawal-related signs upon treatment discontinuation that would be indicative of physical dependence. OUTCOMES Daridorexant showed no signs of abuse or dependence potential in rats. Our data indicate that daridorexant, like other DORAs, has a low potential for abuse in humans.
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Affiliation(s)
| | - Michael Toeroek-Schafroth
- Idorsia Pharmaceuticals Ltd, Allschwil, Switzerland
- Current affiliation: Galapagos GmbH, Basel, Switzerland
| | | | - Lisa Dacome
- Aptuit Srl, An Evotec Company, Verona, Italy
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Corbett J, Young JS, Tipton MJ, Costello JT, Williams TB, Walker EF, Lee BJ, Stevens CE. Molecular biomarkers for assessing the heat-adapted phenotype: a narrative scoping review. J Physiol Sci 2023; 73:26. [PMID: 37848829 DOI: 10.1186/s12576-023-00882-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 10/03/2023] [Indexed: 10/19/2023]
Abstract
Heat acclimation/acclimatisation (HA) mitigates heat-related decrements in physical capacity and heat-illness risk and is a widely advocated countermeasure for individuals operating in hot environments. The efficacy of HA is typically quantified by assessing the thermo-physiological responses to a standard heat acclimation state test (i.e. physiological biomarkers), but this can be logistically challenging, time consuming, and expensive. A valid molecular biomarker of HA would enable evaluation of the heat-adapted state through the sampling and assessment of a biological medium. This narrative review examines candidate molecular biomarkers of HA, highlighting the poor sensitivity and specificity of these candidates and identifying the current lack of a single 'standout' biomarker. It concludes by considering the potential of multivariable approaches that provide information about a range of physiological systems, identifying a number of challenges that must be overcome to develop a valid molecular biomarker of the heat-adapted state, and highlighting future research opportunities.
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Affiliation(s)
- J Corbett
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK.
| | - J S Young
- National Horizons Centre, Teesside University, Darlington, UK
| | - M J Tipton
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
| | - J T Costello
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
| | - T B Williams
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
| | - E F Walker
- Defence Science and Technology Laboratory, Porton Down, Salisbury, UK
| | - B J Lee
- Occupational and Environmental Physiology Group, Centre for Sport, Exercise and Life Sciences, Faculty of Health and Life Sciences, Coventry University, Coventry, UK
| | - C E Stevens
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
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Gangitano E, Martinez-Sanchez N, Bellini MI, Urciuoli I, Monterisi S, Mariani S, Ray D, Gnessi L. Weight Loss and Sleep, Current Evidence in Animal Models and Humans. Nutrients 2023; 15:3431. [PMID: 37571368 PMCID: PMC10420950 DOI: 10.3390/nu15153431] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 07/24/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023] Open
Abstract
Sleep is a vital process essential for survival. The trend of reduction in the time dedicated to sleep has increased in industrialized countries, together with the dramatic increase in the prevalence of obesity and diabetes. Short sleep may increase the risk of obesity, diabetes and cardiovascular disease, and on the other hand, obesity is associated with sleep disorders, such as obstructive apnea disease, insomnia and excessive daytime sleepiness. Sleep and metabolic disorders are linked; therefore, identifying the physiological and molecular pathways involved in sleep regulation and metabolic homeostasis can play a major role in ameliorating the metabolic health of the individual. Approaches aimed at reducing body weight could provide benefits for both cardiometabolic risk and sleep quality, which indirectly, in turn, may determine an amelioration of the cardiometabolic phenotype of individuals. We revised the literature on weight loss and sleep, focusing on the mechanisms and the molecules that may subtend this relationship in humans as in animal models.
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Affiliation(s)
- Elena Gangitano
- OCDEM Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford OX3 7LE, UK
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy
| | - Noelia Martinez-Sanchez
- OCDEM Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford OX3 7LE, UK
| | | | - Irene Urciuoli
- Department of Surgery, Sapienza University of Rome, 00161 Rome, Italy
| | - Stefania Monterisi
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
| | - Stefania Mariani
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy
| | - David Ray
- OCDEM Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford OX3 7LE, UK
| | - Lucio Gnessi
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy
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4
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Core body temperature varies according to the time of exercise without affecting orexin-A production in the dorsolateral hypothalamus in rat. J Therm Biol 2023. [DOI: 10.1016/j.jtherbio.2023.103522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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Jia MQ, Wang YJ, Fu K, Jiao H, Sun J, Gao Y. Orexin receptor type 2 agonism inhibits thermogenesis in brown adipose tissue by attenuating afferent innervation. J Biomed Res 2022; 36:195-207. [PMID: 35660653 PMCID: PMC9179112 DOI: 10.7555/jbr.36.20220033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Orexin signaling has been associated with energy expenditure and brown adipose tissue (BAT) function. However, conflicting data exist in the field about how orexin signaling regulates BAT thermogenesis. In this study, we show that a specific orexin receptor type 2 (OX2R) agonist [Ala11, D-Leu15]-OxB (OB-Ala) inhibited intrascapular brown adipose tissue (iBAT) thermogenesis by reducing sympathetic output to iBAT. This effect is mediated by OX2Rs located on afferent nerve endings innervating iBAT instead of brown adipocyte itself. Microinjection of OB-Ala into iBAT inhibited iBAT thermogenesis in mice upon cold exposure and neuronal activity in the paraventricular nucleus. Findings suggest that OB-Ala could inhibit iBAT thermogenesis by attenuating sensory input thereby inhibiting the sympathetic-sensory iBAT feedback loop. Our study uncovers a novel primary action site of orexin in the regulation of energy balance.
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Affiliation(s)
- Mo-qiu Jia
- Key Laboratory of Cardiovascular and Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Yong-jin Wang
- Key Laboratory of Cardiovascular and Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Kang Fu
- Key Laboratory of Cardiovascular and Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Han Jiao
- Key Laboratory of Cardiovascular and Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Jia Sun
- Key Laboratory of Cardiovascular and Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Yuanqing Gao
- Key Laboratory of Cardiovascular and Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu 211166, China
- Yuanqing Gao, Key Laboratory of Cardiovascular and Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, 101 Longmian Avenue, Jiangning District, Nanjing, Jiangsu 211166, China. Tel: +86-25 86868467. E-mail:
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Olsen N, Furlong TM, Carrive P. Behavioural and cardiovascular effects of orexin-A infused into the central amygdala under basal and fear conditions in rats. Behav Brain Res 2021; 415:113515. [PMID: 34371088 DOI: 10.1016/j.bbr.2021.113515] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 07/16/2021] [Accepted: 08/03/2021] [Indexed: 10/20/2022]
Abstract
The neuropeptide orexin-A (OX-A) has diverse functions, including maintaining arousal, autonomic control, motor activity and stress responses. These functions are regulated at different terminal regions where OX-A is released. The current study examined the physiological and behavioural effects of OX-A microinjections into the central amygdala (CeA) under basal and stressed conditions in rats. When OX-A was microinjected into the CeA and the animals returned to the home-cage, heart rate and mean arterial pressure were increased compared to vehicle-injected controls. General activity of the animal was also increased, indicating that OX-A activity in CeA contributes to increased arousal. This outcome is similar to the effects of central intracerebroventricular infusions of OX-A, as well as the cardiovascular effects previously demonstrated at many of OX's efferent hypothalamic and brainstem structures. In a second study, animals were fear-conditioned to a context by delivery of electric footshocks and then animals were re-exposed to the conditioned context at test. When OX-A was microinjected at test, freezing behaviour was reduced and there was a corresponding increase in the animal's activity but no impact on the pressor and cardiac responses (i.e, blood pressure and heart rate were unchanged). This reduction in freezing suggests that OX-A activates amygdala neurons that inhibit freezing, which is similar to the actions of other neuropeptides in the CeA that modulate the appropriate defence response to fearful stimuli. Overall, these data indicate that the CeA is an important site of OX-A modulation of cardiovascular and motor activity, as well as conditioned freezing responses.
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Affiliation(s)
- Nick Olsen
- School of Medical Sciences, The University of New South Wales, Sydney, Australia
| | - Teri M Furlong
- School of Medical Sciences, The University of New South Wales, Sydney, Australia; Neuroscience Research Australia, Randwick, Australia.
| | - Pascal Carrive
- School of Medical Sciences, The University of New South Wales, Sydney, Australia
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Martin T, Dauvilliers Y, Koumar OC, Bouet V, Freret T, Besnard S, Dauphin F, Bessot N. Dual orexin receptor antagonist induces changes in core body temperature in rats after exercise. Sci Rep 2019; 9:18432. [PMID: 31804545 PMCID: PMC6895233 DOI: 10.1038/s41598-019-54826-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 11/14/2019] [Indexed: 02/02/2023] Open
Abstract
Hypothalamic orexin neurons are involved in various physiological functions, including thermoregulation. The orexinergic system has been considered as a potent mediator of the exercise response. The present study describes how the antagonization of the orexinergic system by a dual orexin receptor antagonist (DORA) modifies the thermoregulatory process during exercise. Core Body Temperature (CBT) and Spontaneous Locomotor Activity (SLA) of 12 male Wistar rats were recorded after either oral administration of DORA (30 mg/kg or 60 mg/kg) or placebo solution, both at rest and in exercise conditions with treadmill running. DORA ingestion decreased SLA for 8 hours (p < 0.001) and CBT for 4 hours (p < 0.01). CBT (°C) response was independent of SLA. The CBT level decreased from the beginning to the end of exercise when orexin receptors were antagonized, with a dose-dependent response (39.09 ± 0.36 and 38.88 ± 0.28 for 30 and 60 mg/kg; p < 0.001) compared to placebo (39.29 ± 0.31; p < 0.001). CBT increased during exercise was also blunted after DORA administration, but without dose effects of DORA. In conclusion, our results favor the role of orexin in the thermoregulation under stress related to exercise conditions.
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Affiliation(s)
- Tristan Martin
- Normandie Univ, Unicaen, INSERM, COMETE, 14000, Caen, France
| | - Yves Dauvilliers
- Reference National Center for Narcolepsy, Sleep Unit, Department of Neurology, Gui-de-Chauliac Hospital, University of Montpellier, Montpellier, INSERM U1061, France
| | | | - Valentine Bouet
- Normandie Univ, Unicaen, INSERM, COMETE, 14000, Caen, France
| | - Thomas Freret
- Normandie Univ, Unicaen, INSERM, COMETE, 14000, Caen, France
| | | | | | - Nicolas Bessot
- Normandie Univ, Unicaen, INSERM, COMETE, 14000, Caen, France.
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Milbank E, López M. Orexins/Hypocretins: Key Regulators of Energy Homeostasis. Front Endocrinol (Lausanne) 2019; 10:830. [PMID: 31920958 PMCID: PMC6918865 DOI: 10.3389/fendo.2019.00830] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 11/13/2019] [Indexed: 12/29/2022] Open
Abstract
Originally described to be involved in feeding regulation, orexins/hypocretins are now also considered as major regulatory actors of numerous biological processes, such as pain, sleep, cardiovascular function, neuroendocrine regulation, and energy expenditure. Therefore, they constitute one of the most pleiotropic families of hypothalamic neuropeptides. Although their orexigenic effect is well documented, orexins/hypocretins also exert central effects on energy expenditure, notably on the brown adipose tissue (BAT) thermogenesis. A better comprehension of the underlying mechanisms and potential interactions with other hypothalamic molecular pathways involved in the modulation of food intake and thermogenesis, such as AMP-activated protein kinase (AMPK) and endoplasmic reticulum (ER) stress, is essential to determine the exact implication and pathophysiological relevance of orexins/hypocretins on the control of energy balance. Here, we will review the actions of orexins on energy balance, with special focus on feeding and brown fat function.
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Affiliation(s)
- Edward Milbank
- Department of Physiology, CIMUS, Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
- *Correspondence: Edward Milbank
| | - Miguel López
- Department of Physiology, CIMUS, Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
- Miguel López
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9
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Antelmi E, Plazzi G, Pizza F, Vandi S, Aricò D, Ferri R. Impact of acute administration of sodium oxybate on heart rate variability in children with type 1 narcolepsy. Sleep Med 2018; 47:1-6. [PMID: 29880141 DOI: 10.1016/j.sleep.2018.03.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 03/08/2018] [Accepted: 03/12/2018] [Indexed: 01/25/2023]
Abstract
BACKGROUND Currently, cardiovascular measurements in children affected with type 1 narcolepsy (NT1) have never been investigated, and neither have their modulation by the administration of sodium oxybate (SO). METHODS Twelve drug-naïve NT1 children (four males, eight females) with a mean age of 11 ± 3.16 years underwent a nocturnal polysomnography, at baseline and during the first night of SO administration. Data were contrasted with those recorded in 23 age-matched healthy controls. Heart rate variability (HRV) analysis was performed by analyzing the electrocardiogram signal for automatic detection of R waves with a computer program calculating a series of standard time-domain measures and obtaining spectral parameters, by means of a Fast-Fourier Transform. RESULTS In sleep stages N2 and N3, NT1 children showed increased power in the low-frequency (LF) and very-LF (VLF) ranges, when compared to controls. In addition, HRV (as measured by time domain parameters) during all sleep stages tended to be slightly higher in patients when compared to controls. Treatment with SO did not change significantly any parameter, but an overall trend to mildly decreased HRV that reached a significant value only during R sleep. CONCLUSIONS HRV during all sleep stages tended to be slightly higher in young patients when compared to controls, confirming the presence of a slight sympathovagal system imbalance even in NT1 children. SO tends to decrease these values especially during REM sleep and in that regard, further studies supporting these preliminary findings and considering the long-term effects of SO on heart rate parameters are warranted.
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Affiliation(s)
- Elena Antelmi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy.
| | - Giuseppe Plazzi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
| | - Fabio Pizza
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
| | - Stefano Vandi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
| | - Debora Aricò
- Sleep Research Centre, Department of Neurology I.C., Oasi Institute IRCCS, Troina, Italy
| | - Raffaele Ferri
- Sleep Research Centre, Department of Neurology I.C., Oasi Institute IRCCS, Troina, Italy
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Öz P, Gökalp HK, Göver T, Uzbay T. Dose-dependent and opposite effects of orexin A on prepulse inhibition response in sleep-deprived and non-sleep-deprived rats. Behav Brain Res 2017; 346:73-79. [PMID: 29237551 DOI: 10.1016/j.bbr.2017.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/19/2017] [Accepted: 12/04/2017] [Indexed: 01/20/2023]
Abstract
Orexin is a novel neurotransmitter released from lateral hypothalamus, that is a crucial modulator in sleep/wakefulness system. Recent studies also suggest its possible role in the neurodevelopmental disorders, such as schizophrenia. Our study consists of two experiments, where we investigate the effect of orexin A (OXA), one of two isoforms of orexin that can pass blood brain barrier, on the prepulse inhibition of acoustic startle reflex. The first experiment tested the effect of OXA on PPI response of non-sleep-deprived rats via intraperitoneal injection 30min before testing. Our results show that 40μg/kg OXA attenuates PPI% at 78dB and 86dB prepulse intensities. The second experiment utilized 72-h REM sleep deprivation, as a model for sleep-deprivation-induced impairment of PPI response. Here, we tested the effect of OXA on PPI% of sleep-deprived rats via intraperitoneal injection at the last 30min of sleep deprivation, testing for PPI immediately afterwards. Our results showed that (1) sleep deprivation attenuates the PPI% at 74dB, 78dB and 86dB prepulse intensities and (2) 10μg/kg OXA completely restores the impaired PPI% at 78dB only, where the highest PPI% impairment was observed. These results suggest that orexin A modulates PPI response in rats in a dose-dependent manner, oppositely for non-sleep-deprived and sleep-deprived rats, and a more detailed investigation for the etiology of this effect should follow.
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Affiliation(s)
- Pınar Öz
- Neuropsychopharmacology Application and Research Center, Üsküdar University, İstanbul, Turkey; Department of Molecular Biology and Genetics, Üsküdar University, İstanbul, Turkey.
| | - H Kübra Gökalp
- Department of Molecular Biology and Genetics, Üsküdar University, İstanbul, Turkey
| | - Tansu Göver
- Department of Molecular Biology and Genetics, Üsküdar University, İstanbul, Turkey
| | - Tayfun Uzbay
- Neuropsychopharmacology Application and Research Center, Üsküdar University, İstanbul, Turkey; Department of Molecular Biology and Genetics, Üsküdar University, İstanbul, Turkey
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Messina G, Di Bernardo G, Viggiano A, De Luca V, Monda V, Messina A, Chieffi S, Galderisi U, Monda M. Exercise increases the level of plasma orexin A in humans. J Basic Clin Physiol Pharmacol 2017; 27:611-616. [PMID: 27665420 DOI: 10.1515/jbcpp-2015-0133] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 07/18/2016] [Indexed: 01/11/2023]
Abstract
BACKGROUND The purpose of this research was to study the effects of exercise on the concentration of plasma orexin A, a peptide regulating several physiological functions. METHODS Blood samples were collected from participants (men, n=10; age: 24.4±2.93 years) 15, 0 min before the start of exercise, and 30, 45, 60 min after a cycle ergometer exercise at 75 W for 15 min. Also heart rate (HR), galvanic skin response (GSR), and rectal temperature were monitored. RESULTS The exercise induced a significant increase (p<0.01) in plasmatic orexin A with a peak at 30 min after the exercise bout, in association with an increase of the other three monitored variables: HR (p<0.01), GSR (p<0.05), and rectal temperature (p<0.01). CONCLUSIONS Our findings indicate that plasmatic orexin A is involved in the reaction to physical activity.
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12
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Contreras C, Nogueiras R, Diéguez C, Rahmouni K, López M. Traveling from the hypothalamus to the adipose tissue: The thermogenic pathway. Redox Biol 2017; 12:854-863. [PMID: 28448947 PMCID: PMC5406580 DOI: 10.1016/j.redox.2017.04.019] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/08/2017] [Accepted: 04/11/2017] [Indexed: 01/13/2023] Open
Abstract
Brown adipose tissue (BAT) is a specialized tissue critical for non-shivering thermogenesis producing heat through mitochondrial uncoupling; whereas white adipose tissue (WAT) is responsible of energy storage in the form of triglycerides. Another type of fat has been described, the beige adipose tissue; this tissue emerges in existing WAT depots but with thermogenic ability, a phenomenon known as browning. Several peripheral signals relaying information about energy status act in the brain, particularly the hypothalamus, to regulate thermogenesis in BAT and browning of WAT. Different hypothalamic areas have the capacity to regulate the thermogenic process in brown and beige adipocytes through the sympathetic nervous system (SNS). This review discusses important concepts and discoveries about the central control of thermogenesis as a trip that starts in the hypothalamus, and taking the sympathetic roads to reach brown and beige fat to modulate thermogenic functions.
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Affiliation(s)
- Cristina Contreras
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela 15706, Spain.
| | - Rubén Nogueiras
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela 15706, Spain
| | - Carlos Diéguez
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela 15706, Spain
| | - Kamal Rahmouni
- Department of Pharmacology, University of Iowa, Iowa City, Iowa 52242, USA; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa 52242, USA
| | - Miguel López
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela 15706, Spain.
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13
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Contreras C, Nogueiras R, Diéguez C, Medina-Gómez G, López M. Hypothalamus and thermogenesis: Heating the BAT, browning the WAT. Mol Cell Endocrinol 2016; 438:107-115. [PMID: 27498420 DOI: 10.1016/j.mce.2016.08.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 07/30/2016] [Accepted: 08/01/2016] [Indexed: 12/20/2022]
Abstract
Brown adipose tissue (BAT) has been also considered as the main thermogenic organ responsible of maintenance body temperature through heat production. However, a new type of thermogenic fat has been characterized during the last years, the beige or brite fat, that is developed from white adipose tissue (WAT) in response to different stimuli by a process known as browning. The activities of brown and beige adipocytes ameliorate metabolic disease, including obesity in mice and correlate with leanness in humans. Many genes and pathways that regulate brown and beige adipocyte biology have now been identified, providing a variety of promising therapeutic targets for metabolic disease. The hypothalamus is the main central place orchestrating the outflow signals that drive the sympathetic nerve activity to BAT and WAT, controlling heat production and energy homeostasis. Recent data have revealed new hypothalamic molecular mechanisms, such as hypothalamic AMP-activated protein kinase (AMPK), that control both thermogenesis and browning. This review provides an overview of the factors influencing BAT and WAT thermogenesis, with special focus on the integration of peripheral information on hypothalamic circuits controlling thermoregulation.
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Affiliation(s)
- Cristina Contreras
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, 15706, Spain.
| | - Rubén Nogueiras
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, 15706, Spain
| | - Carlos Diéguez
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, 15706, Spain
| | - Gema Medina-Gómez
- Área de Bioquímica y Biología Molecular, Departamento de Ciencias Básicas de la Salud, Universidad Rey Juan Carlos, 28922, Alcorcón, Madrid, Spain
| | - Miguel López
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, 15706, Spain.
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Miyata K, Kuwaki T, Ootsuka Y. The integrated ultradian organization of behavior and physiology in mice and the contribution of orexin to the ultradian patterning. Neuroscience 2016; 334:119-133. [PMID: 27491480 DOI: 10.1016/j.neuroscience.2016.07.041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 07/22/2016] [Accepted: 07/26/2016] [Indexed: 11/15/2022]
Abstract
Our series of rat experiments have shown that locomotor activity, arousal level, body and brown adipose tissue temperatures, heart rate and arterial pressure increase episodically in an integrated manner approximately every 100min (ultradian manner). Although it has been proposed that the integrated ultradian pattern is a fundamental biological rhythm across species, there are no reports of the integrated ultradian pattern in species other than rats. The aim of the present study was to establish a mouse model using simultaneous recording of locomotor activity, eating behavior, body temperature, heart rate and arousal in order to determine whether their behavior and physiology are organized in an ultradian manner in normal (wild-type) mice. We also incorporated the same recording in prepro-orexin knockout (ORX-KO) mice to reveal the role of orexin in the brain mechanisms underlying ultradian patterning. The orexin system is one of the key conductors required for coordinating autonomic functions and behaviors, and thus may contribute to ultradian patterning. In wild-type mice, locomotor activity, arousal level, body temperature and heart rate increased episodically every 93±18min (n=8) during 24h. Eating was integrated into the ultradian pattern, commencing 23±4min (n=8) after the onset of an electroencephalogram (EEG) ultradian episode. The integrated ultradian pattern in wild-type mice is very similar to that observed in rats. In ORX-KO mice, the ultradian episodic changes in locomotor activity, EEG arousal indices and body temperature were significantly attenuated, but the ultradian patterning was preserved. Our findings support the view that the ultradian pattern is common across species. The present results also suggest that orexin contributes to driving ultradian episodic changes, however, this neuropeptide is not essential for the generation of the ultradian pattern.
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Affiliation(s)
- Kohei Miyata
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Tomoyuki Kuwaki
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Youichirou Ootsuka
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan; Centre for Neuroscience, Department of Human Physiology, School of Medicine, Flinders University, South Australia, Australia.
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15
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Flores Á, Julià-Hernández M, Maldonado R, Berrendero F. Involvement of the orexin/hypocretin system in the pharmacological effects induced by Δ(9) -tetrahydrocannabinol. Br J Pharmacol 2016; 173:1381-92. [PMID: 26799708 DOI: 10.1111/bph.13440] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 01/12/2016] [Accepted: 01/17/2016] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND AND PURPOSE Anatomical, biochemical and pharmacological evidence suggest the existence of a crosstalk between the orexinergic and endocannabinoid systems. While the orexin receptor 1 (OX1 receptor) modulates the reinforcing properties of cannabinoids, the participation of orexins in the acute pharmacological effects of Δ(9) -tetrahydrocannabinol (THC) remains unexplored. EXPERIMENTAL APPROACH We assessed the possible role of orexins in THC-induced hypolocomotion, hypothermia, antinociception, anxiolytic- and anxiogenic-like effects and memory impairment. Selective OX1 and OX2 receptor antagonists and OX1 knockout (KO) mice as well as prepro-orexin (PPO) KO mice were used as pharmacological and genetic approaches. CB1 receptor levels in control and PPO KO mice were evaluated by immunoblot analysis. The expression of c-Fos after THC treatment was analysed in several brain areas in wild-type mice and in mice lacking the PPO gene. KEY RESULTS The hypothermia, supraspinal antinociception and anxiolytic-like effects induced by THC were modulated by orexins through OX2 receptor signalling. OX1 receptors did not seem to be involved in these THC responses. No differences in CB1 receptor levels were found between wild-type and PPO KO mice. THC-induced increase in c-Fos expression was reduced in the central amygdala, medial preoptic area and lateral septum in these mutant mice. CONCLUSIONS AND IMPLICATIONS Our results provide new findings to further clarify the interaction between orexins and cannabinoids. OX1 and OX2 receptors are differently implicated in the pharmacological effects of cannabinoids.
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Affiliation(s)
- África Flores
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, PRBB, Barcelona, Spain
| | - Marina Julià-Hernández
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, PRBB, Barcelona, Spain
| | - Rafael Maldonado
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, PRBB, Barcelona, Spain
| | - Fernando Berrendero
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, PRBB, Barcelona, Spain
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16
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Abstract
Initially implicated in the regulation of feeding, orexins/hypocretins are now acknowledged to play a major role in the control of a wide variety of biological processes, such as sleep, energy expenditure, pain, cardiovascular function and neuroendocrine regulation, a feature that makes them one of the most pleiotropic families of hypothalamic neuropeptides. While the orexigenic effect of orexins is well described, their central effects on energy expenditure and particularly on brown adipose tissue (BAT) thermogenesis are not totally unraveled. Better understanding of these actions and their possible interrelationship with other hypothalamic systems controlling thermogenesis, such as AMP-activated protein kinase (AMPK) and endoplasmic reticulum (ER) stress, will help to clarify the exact role and pathophysiological relevance of these neuropeptides have on energy balance.
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Affiliation(s)
- Johan Fernø
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; Department of Clinical Science, K. G. Jebsen Center for Diabetes Research, University of Bergen, N-5021 Bergen, Norway.
| | - Rosa Señarís
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain
| | - Carlos Diéguez
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn) 15706, Spain
| | - Manuel Tena-Sempere
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn) 15706, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Hospital Reina Sofía, 14004 Córdoba, Spain; FiDiPro Program, Department of Physiology, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland
| | - Miguel López
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn) 15706, Spain.
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17
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Contreras C, Gonzalez F, Fernø J, Diéguez C, Rahmouni K, Nogueiras R, López M. The brain and brown fat. Ann Med 2015; 47:150-68. [PMID: 24915455 PMCID: PMC4438385 DOI: 10.3109/07853890.2014.919727] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Accepted: 04/25/2014] [Indexed: 02/06/2023] Open
Abstract
Brown adipose tissue (BAT) is a specialized organ responsible for thermogenesis, a process required for maintaining body temperature. BAT is regulated by the sympathetic nervous system (SNS), which activates lipolysis and mitochondrial uncoupling in brown adipocytes. For many years, BAT was considered to be important only in small mammals and newborn humans, but recent data have shown that BAT is also functional in adult humans. On the basis of this evidence, extensive research has been focused on BAT function, where new molecules, such as irisin and bone morphogenetic proteins, particularly BMP7 and BMP8B, as well as novel central factors and new regulatory mechanisms, such as orexins and the canonical ventomedial nucleus of the hypothalamus (VMH) AMP- activated protein kinase (AMPK)-SNS-BAT axis, have been discovered and emerged as potential drug targets to combat obesity. In this review we provide an overview of the complex central regulation of BAT and how different neuronal cell populations co-ordinately work to maintain energy homeostasis.
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Affiliation(s)
- Cristina Contreras
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria , Santiago de Compostela, 15782 , Spain
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18
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Messina G, Dalia C, Tafuri D, Monda V, Palmieri F, Dato A, Russo A, De Blasio S, Messina A, De Luca V, Chieffi S, Monda M. Orexin-A controls sympathetic activity and eating behavior. Front Psychol 2014; 5:997. [PMID: 25250003 PMCID: PMC4157463 DOI: 10.3389/fpsyg.2014.00997] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 08/21/2014] [Indexed: 12/13/2022] Open
Abstract
It is extremely important for the health to understand the regulatory mechanisms of energy expenditure. These regulatory mechanisms play a central role in the pathogenesis of body weight alteration. The hypothalamus integrates nutritional information derived from all peripheral organs. This region of the brain controls hormonal secretions and neural pathways of the brainstem. Orexin-A is a hypothalamic neuropeptide involved in the regulation of feeding behavior, sleep-wakefulness rhythm, and neuroendocrine homeostasis. This neuropeptide is involved in the control of the sympathetic activation, blood pressure, metabolic status, and blood glucose level. This minireview focuses on relationship between the sympathetic nervous system and orexin-A in the control of eating behavior and energy expenditure. The “thermoregulatory hypothesis” of food intake is analyzed, underlining the role played by orexin-A in the control of food intake related to body temperature. Furthermore, the paradoxical eating behavior induced orexin-A is illustrated in this minireview.
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Affiliation(s)
- Giovanni Messina
- Section of Human Physiology and Clinical Dietetic Service, Department of Experimental Medicine, Second University of Naples Naples, Italy
| | - Carmine Dalia
- Section of Human Physiology and Clinical Dietetic Service, Department of Experimental Medicine, Second University of Naples Naples, Italy
| | - Domenico Tafuri
- Faculty of Motor Sciences, Parthenope University of Naples Naples, Italy
| | - Vincenzo Monda
- Section of Human Physiology and Clinical Dietetic Service, Department of Experimental Medicine, Second University of Naples Naples, Italy
| | - Filomena Palmieri
- Section of Human Physiology and Clinical Dietetic Service, Department of Experimental Medicine, Second University of Naples Naples, Italy
| | - Amelia Dato
- Section of Human Physiology and Clinical Dietetic Service, Department of Experimental Medicine, Second University of Naples Naples, Italy
| | - Angelo Russo
- Section of Human Physiology and Clinical Dietetic Service, Department of Experimental Medicine, Second University of Naples Naples, Italy
| | - Saverio De Blasio
- Section of Human Physiology and Clinical Dietetic Service, Department of Experimental Medicine, Second University of Naples Naples, Italy
| | - Antonietta Messina
- Section of Human Physiology and Clinical Dietetic Service, Department of Experimental Medicine, Second University of Naples Naples, Italy
| | - Vincenzo De Luca
- Department of Psychiatry, University of Toronto Toronto, ON, Canada
| | - Sergio Chieffi
- Section of Human Physiology and Clinical Dietetic Service, Department of Experimental Medicine, Second University of Naples Naples, Italy
| | - Marcellino Monda
- Section of Human Physiology and Clinical Dietetic Service, Department of Experimental Medicine, Second University of Naples Naples, Italy
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19
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Affiliation(s)
- Dyan Sellayah
- Metabolic Signaling and Disease Program; Diabetes and Obesity Research Center; Sanford-Burnham Medical Research Institute; Orlando Florida
| | - Devanjan Sikder
- Metabolic Signaling and Disease Program; Diabetes and Obesity Research Center; Sanford-Burnham Medical Research Institute; Orlando Florida
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20
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Shin YO, Lee JB, Min YK, Yang HM. Heat acclimation affects circulating levels of prostaglandin E2, COX-2 and orexin in humans. Neurosci Lett 2013; 542:17-20. [PMID: 23523649 DOI: 10.1016/j.neulet.2013.03.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Revised: 02/07/2013] [Accepted: 03/04/2013] [Indexed: 12/28/2022]
Abstract
We examined serum levels of prostaglandin E2 (PGE2), cyclooxygenase (COX)-2 and orexin before and after heat acclimation (HA) to test the hypothesis that decreased basal body temperature due to HA correlate with circulating levels of these key thermoregulatory molecules. Nine healthy human male volunteers were recruited (age, 21.9±2.7 years). The subjects were exposed to half-body immersion in hot water (42±0.5°C) at the same time of day (2-5p.m.) on alternate days for 3 weeks. The HA protocol included 10 bouts of 30min immersion. All experiments were performed in an automated climate chamber (temperature, 26.0±0.5°C; relative humidity, 60±3.0%; air velocity, <1m/s). Tympanic and skin temperatures were measured, and mean body temperature was calculated. The difference in body weight was used to estimate total sweat loss. Serum levels of PGE2, COX-2 and orexin were analyzed before and after HA. Body temperature decreased significantly (P<0.05) after HA, whereas sweat volume increased significantly (P<0.01). Serum PGE2, COX-2 and orexin concentrations decreased significantly compared to those at pre-acclimation (P<0.001, P<0.01, P<0.01, respectively). Our data suggest that decreased basal body temperature after HA is associated with decreases in thermoregulatory molecules, such as PGE2, COX-2 and orexin.
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Affiliation(s)
- Young Oh Shin
- Department of Healthcare, Global Graduate School, Soonchunhyang University, 646 Asan, Republic of Korea
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21
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Kukkonen JP. Physiology of the orexinergic/hypocretinergic system: a revisit in 2012. Am J Physiol Cell Physiol 2012; 304:C2-32. [PMID: 23034387 DOI: 10.1152/ajpcell.00227.2012] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The neuropeptides orexins and their G protein-coupled receptors, OX(1) and OX(2), were discovered in 1998, and since then, their role has been investigated in many functions mediated by the central nervous system, including sleep and wakefulness, appetite/metabolism, stress response, reward/addiction, and analgesia. Orexins also have peripheral actions of less clear physiological significance still. Cellular responses to the orexin receptor activity are highly diverse. The receptors couple to at least three families of heterotrimeric G proteins and other proteins that ultimately regulate entities such as phospholipases and kinases, which impact on neuronal excitation, synaptic plasticity, and cell death. This article is a 10-year update of my previous review on the physiology of the orexinergic/hypocretinergic system. I seek to provide a comprehensive update of orexin physiology that spans from the molecular players in orexin receptor signaling to the systemic responses yet emphasizing the cellular physiological aspects of this system.
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Affiliation(s)
- Jyrki P Kukkonen
- Dept. of Veterinary Biosciences, University of Helsinki, Finland.
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22
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Perez-Leighton CE, Boland K, Teske JA, Billington C, Kotz CM. Behavioral responses to orexin, orexin receptor gene expression, and spontaneous physical activity contribute to individual sensitivity to obesity. Am J Physiol Endocrinol Metab 2012; 303:E865-74. [PMID: 22829584 PMCID: PMC3469621 DOI: 10.1152/ajpendo.00119.2012] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 07/20/2012] [Indexed: 01/08/2023]
Abstract
There is significant variability in diet-induced obesity (DIO) among humans and rodents, which has been associated with differences in intrinsic spontaneous physical activity (SPA). The orexin neuropeptides positively modulate SPA through multiple brain sites, but the effects of DIO on orexin's activity are not well understood. In this study, we tested the hypothesis that DIO sensitivity is mediated by decreased SPA and changes in the function of the orexins. As a DIO model, we used male Sprague-Dawley rats fed a high-fat (HF; 45% kcal from fat) or a low-fat (LF; 10% kcal from fat) diet for 10 wk. We measured SPA before and after HF or LF feeding and expression of orexin receptors by real-time PCR after dietary treatments. We tested DIO effects on orexin signaling by measuring SPA after injection of orexin A in the rostral lateral hypothalamus (RLH) before and after 10 wk of HF feeding. Finally, we tested whether daily orexin A RLH injections prevent DIO caused by HF feeding. Our results show that resistance to DIO is associated with an increase in SPA, SPA after injection of orexin A in RLH, and orexin receptor expression in sites that mediate orexin's effect on SPA, including RLH. We show that daily injections of orexin peptide in RLH prevent DIO without altering food intake. We estimate that the energetic cost of SPA after orexin A RLH injection accounts for approximately 61% of the extra caloric intake associated with HF intake, suggesting additional effects of orexins. In summary, our results suggest that variability in DIO sensitivity is mediated through adaptations in the activity of the orexin peptides and their receptors.
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23
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Abstract
The orexins/hypocretins are endogenous, modulatory and multifunctional neuropeptides with prominent influence on several physiological processes. The influence of orexins on energy expenditure is highlighted with focus on orexin action on individual components of energy expenditure. As orexin stabilizes and maintains normal states of arousal and the sleep/wake cycle, we also highlight orexin mediation of sleep and how sleep interacts with energy expenditure.
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Affiliation(s)
- Jennifer A Teske
- Department of Nutritional Sciences, University of Arizona and Southern Arizona VA Health Care System, Tucson, Arizona, USA
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24
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Abstract
In this chapter, we give an overview of the current status of the role of orexins in feeding and energy homeostasis. Orexins, also known as hypocretins, initially were discovered in 1998 as hypothalamic regulators of food intake. A little later, their far more important function as regulators of sleep and arousal came to light. Despite their restricted distribution, orexin neurons have projections throughout the entire brain, with dense projections especially to the paraventricular nucleus of the thalamus, the arcuate nucleus of the hypothalamus, and the locus coeruleus and tuberomammillary nucleus. Its two receptors are orexin receptor 1 and orexin receptor 2. These receptors show a specific and localized distribution in a number of brain regions, and a variety of different actions has been demonstrated upon their binding. Our group showed that through the autonomic nervous system, the orexin system plays a key role in the control of glucose metabolism, but it has also been shown to stimulate sympathetic outflow, to increase body temperature, heart rate, blood pressure, and renal sympathetic nerve activity. The well-known effects of orexin on the control of food intake, arousal, and wakefulness appear to be more extensive than originally thought, with additional effects on the autonomic nervous system, that is, to increase body temperature and energy metabolism.
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25
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Nixon JP, Kotz CM, Novak CM, Billington CJ, Teske JA. Neuropeptides controlling energy balance: orexins and neuromedins. Handb Exp Pharmacol 2012:77-109. [PMID: 22249811 DOI: 10.1007/978-3-642-24716-3_4] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In this chapter, we review the feeding and energy expenditure effects of orexin (also known as hypocretin) and neuromedin. Orexins are multifunctional neuropeptides that affect energy balance by participating in regulation of appetite, arousal, and spontaneous physical activity. Central orexin signaling for all functions originates in the lateral hypothalamus-perifornical area and is likely functionally differentiated based on site of action and on interacting neural influences. The effect of orexin on feeding is likely related to arousal in some ways but is nonetheless a separate neural process that depends on interactions with other feeding-related neuropeptides. In a pattern distinct from other neuropeptides, orexin stimulates both feeding and energy expenditure. Orexin increases in energy expenditure are mainly by increasing spontaneous physical activity, and this energy expenditure effect is more potent than the effect on feeding. Global orexin manipulations, such as in transgenic models, produce energy balance changes consistent with a dominant energy expenditure effect of orexin. Neuromedins are gut-brain peptides that reduce appetite. There are gut sources of neuromedin, but likely the key appetite-related neuromedin-producing neurons are in the hypothalamus and parallel other key anorectic neuropeptide expression in the arcuate to paraventricular hypothalamic projection. As with other hypothalamic feeding-related peptides, hindbrain sites are likely also important sources and targets of neuromedin anorectic action. Neuromedin increases physical activity in addition to reducing appetite, thus producing a consistent negative energy balance effect. Together with the other various neuropeptides, neurotransmitters, neuromodulators, and neurohormones, neuromedin and orexin act in the appetite network to produce changes in food intake and energy expenditure, which ultimately influences the regulation of body weight.
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Affiliation(s)
- Joshua P Nixon
- Veterans Affairs Medical Center, Research Service (151), Minneapolis, MN, USA
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26
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Wu MF, Nienhuis R, Maidment N, Lam HA, Siegel JM. Cerebrospinal fluid hypocretin (orexin) levels are elevated by play but are not raised by exercise and its associated heart rate, blood pressure, respiration or body temperature changes. Arch Ital Biol 2011; 149:492-8. [PMID: 22205595 DOI: 10.4449/aib.v149i4.1315] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Hypocretin (Hcrt) has been implicated in the control of motor activity and in respiration and cardiovascular changes. Loss of Hcrt in narcolepsy is linked to sleepiness and to cataplexy, a sudden loss of muscle tone which is triggered by sudden strong emotions. In the current study we have compared the effects of treadmill running, to yard play on cerebrospinal fluid (CSF) Hcrt level in normal dogs. We find that treadmill locomotion, at a wide range of speeds, does not increase Hcrt level beyond baseline, whereas yard play produces a substantial increase in Hcrt, even though both activities produce comparable increases in heart rate, respiration and body temperature. We conclude that motor and cardiovascular changes are not sufficient to elevate CSF levels of Hcrt and we hypothesize that the emotional aspects of yard play account for the observed increase in Hcrt.
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Affiliation(s)
- M-F Wu
- Department of Psychiatry, University of California, Los Angeles, CA, USA
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27
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Sellayah D, Bharaj P, Sikder D. Orexin is required for brown adipose tissue development, differentiation, and function. Cell Metab 2011; 14:478-90. [PMID: 21982708 DOI: 10.1016/j.cmet.2011.08.010] [Citation(s) in RCA: 192] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 06/29/2011] [Accepted: 08/24/2011] [Indexed: 11/19/2022]
Abstract
Orexin (OX) neuropeptides stimulate feeding and arousal. Deficiency of orexin is implicated in narcolepsy, a disease associated with obesity, paradoxically in the face of reduced food intake. Here, we show that obesity in orexin-null mice is associated with impaired brown adipose tissue (BAT) thermogenesis. Failure of thermogenesis in OX-null mice is due to inability of brown preadipocytes to differentiate. The differentiation defect in OX-null neonates is circumvented by OX injections to OX-null dams. In vitro, OX, triggers the full differentiation program in mesenchymal progenitor stem cells, embryonic fibroblasts and brown preadipocytes via p38 mitogen activated protein (MAP) kinase and bone morphogenetic protein receptor-1a (BMPR1A)-dependent Smad1/5 signaling. Our study suggests that obesity associated with OX depletion is linked to brown-fat hypoactivity, which leads to dampening of energy expenditure. Thus, orexin plays an integral role in adaptive thermogenesis and body weight regulation via effects on BAT differentiation and function.
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Affiliation(s)
- Dyan Sellayah
- Metabolic Signaling and Disease Program, Diabetes and Obesity Research Center, Sanford-Burnham Medical Research Institute, Orlando, FL 32827, USA
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28
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Abstract
The hypocretins or orexins are endogenous neuropeptides synthesized in discrete lateral, perifornical and dorsal hypothalamic neurones. These multi-functional neuropeptides modulate energy homeostasis, arousal, stress, reward, reproduction and cardiovascular function. This review summarizes the role of hypocretins in modulating non-sleep-related energy expenditure with specific focus on the augmentation of whole body energy expenditure as well as hypocretin-induced physical activity and sympathetic outflow. We compare the efficacy of hypocretin-1 and 2 on energy expenditure and evaluate whether the literature implicates hypocretin signalling though the hypocretin-1 and -2 receptor as having shared and or functionally specific physiological effects. Thus far data suggest that hypocretin-1 has a more robust stimulatory effect relative to hypocretin-2. Furthermore, hypocretin-1 receptor predominantly mediates behaviours known to influence energy expenditure. Further studies on the hypocretin-2 receptor are needed.
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Affiliation(s)
- J A Teske
- Veterans Affairs Medical Center, Minneapolis, MN 55417, USA.
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29
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Conti B, Sanchez-Alavez M, Winsky-Sommerer R, Morale MC, Lucero J, Brownell S, Fabre V, Huitron-Resendiz S, Henriksen S, Zorrilla EP, de Lecea L, Bartfai T. Transgenic mice with a reduced core body temperature have an increased life span. Science 2006; 314:825-8. [PMID: 17082459 DOI: 10.1126/science.1132191] [Citation(s) in RCA: 274] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Reduction of core body temperature has been proposed to contribute to the increased life span and the antiaging effects conferred by calorie restriction (CR). Validation of this hypothesis has been difficult in homeotherms, primarily due to a lack of experimental models. We report that transgenic mice engineered to overexpress the uncoupling protein 2 in hypocretin neurons (Hcrt-UCP2) have elevated hypothalamic temperature. The effects of local temperature elevation on the central thermostat resulted in a 0.3 degrees to 0.5 degrees C reduction of the core body temperature. Fed ad libitum, Hcrt-UCP2 transgenic mice had the same caloric intake as their wild-type littermates but had increased energy efficiency and a greater median life span (12% increase in males; 20% increase in females). Thus, modest, sustained reduction of core body temperature prolonged life span independent of altered diet or CR.
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Affiliation(s)
- Bruno Conti
- Harold L. Dorris Neurological Research Center, Scripps Research Institute, La Jolla, CA 92037, USA.
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Mochizuki T, Klerman EB, Sakurai T, Scammell TE. Elevated body temperature during sleep in orexin knockout mice. Am J Physiol Regul Integr Comp Physiol 2006; 291:R533-40. [PMID: 16556901 PMCID: PMC2259440 DOI: 10.1152/ajpregu.00887.2005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Core body temperature (Tb) is influenced by many physiological factors, including behavioral state, locomotor activity, and biological rhythms. To determine the relative roles of these factors, we examined Tb in orexin knockout (KO) mice, which have a narcolepsy-like phenotype with severe sleep-wake fragmentation. Because orexin is released during wakefulness and is thought to promote heat production, we hypothesized that orexin KO mice would have lower Tb while awake. Surprisingly, Tb was the same in orexin KO mice and wild-type (WT) littermates during sustained wakefulness. Orexin KO mice had normal diurnal variations in Tb, but the ultradian rhythms of Tb, locomotor activity, and wakefulness were markedly reduced. During the first 15 min of spontaneous sleep, the Tb of WT mice decreased by 1.0 degrees C, but Tb in orexin KO mice decreased only 0.4 degrees C. Even during intense recovery sleep after 8 h of sleep deprivation, the Tb of orexin KO mice remained 0.7 degrees C higher than in WT mice. This blunted fall in Tb during sleep may be due to inadequate activation of heat loss mechanisms or sustained activity in heat-generating systems. These observations reveal an unexpected role for orexin in thermoregulation. In addition, because heat loss is an essential aspect of sleep, the blunted fall in Tb of orexin KO mice may provide an explanation for the fragmented sleep of narcolepsy.
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Affiliation(s)
- Takatoshi Mochizuki
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, USA
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Cerri M, Morrison SF. Activation of lateral hypothalamic neurons stimulates brown adipose tissue thermogenesis. Neuroscience 2006; 135:627-38. [PMID: 16125857 DOI: 10.1016/j.neuroscience.2005.06.039] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 05/25/2005] [Accepted: 06/09/2005] [Indexed: 10/25/2022]
Abstract
The lateral hypothalamic area, containing orexin neurons, is involved in several aspects of autonomic regulation, including thermoregulation and energy expenditure. To determine if activation of lateral hypothalamic area neurons influences sympathetically-regulated thermogenesis in brown adipose tissue, we microinjected bicuculline (120 pmol, 60 nl, unilateral) into the lateral hypothalamic area in urethane/chloralose-anesthetized, artificially-ventilated rats. Disinhibition of neurons in lateral hypothalamic area evoked a significant increase (+1309%) in brown adipose tissue sympathetic nerve activity accompanied by parallel increases in brown adipose tissue temperature (+2.0 degrees C), in expired CO2 (+0.6%), in heart rate (+88 bpm) and in mean arterial pressure (+11 mm Hg). Subsequent microinjections of glycine (30 nmol, 60 nl) to inhibit local neurons in raphe pallidus or in dorsomedial hypothalamus or of glutamate receptor antagonists into dorsomedial hypothalamus promptly reversed the increases in brown adipose tissue sympathetic nerve activity, brown adipose tissue temperature and heart rate evoked by disinhibition of neurons in lateral hypothalamic area. We conclude that neurons in the lateral hypothalamic area can influence brown adipose tissue sympathetic nerve activity, brown adipose tissue thermogenesis and heart rate through pathways that are dependent on the activation of neurons in dorsomedial hypothalamus and raphe pallidus.
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Affiliation(s)
- M Cerri
- Neurological Sciences Institute, Oregon Health and Science University, Beaverton, OR 97006, USA
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Székely M, Pétervári E, Pákai E, Hummel Z, Szelényi Z. Acute, subacute and chronic effects of central neuropeptide Y on energy balance in rats. Neuropeptides 2005; 39:103-15. [PMID: 15752544 DOI: 10.1016/j.npep.2005.01.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2004] [Revised: 12/20/2004] [Accepted: 01/05/2005] [Indexed: 11/19/2022]
Abstract
Central neuropeptide Y (NPY) injection has been reported to cause hyperphagia and in some cases also hypometabolism or hypothermia. Chronic central administration induced a moderate rise of short duration in body weight, without consistent metabolic/thermal changes. In the present studies the acute and subsequent subacute ingestive and metabolic/thermal changes were studied following intracerebroventricular (i.c.v.) injections of NPY in cold-adapted and non-adapted rats, or the corresponding chronic changes following i.c.v. NPY infusion. Besides confirming basic earlier data, we demonstrated novel findings: a temporal relationship for the orexigenic and metabolic/thermal effects, and differences of coordination in acute/subacute/chronic phases or states. The acute phase (30-60 min after injection) was anabolic: coordinated hyperphagia and hypometabolism/hypothermia. NPY evoked a hypothermia by suppressing any (hyper)metabolism in excess of basal metabolic rate, without enhancing heat loss. Thus, acute hypothermia was observed in sub-thermoneutral but not thermoneutral environments. The subsequent subacute catabolic phase exhibited opposite effects: slight increase in metabolic rate, rise in body temperature, reaching a plateau within 3-4 h after injection -- this was maintained for at least 24 h; meanwhile the food intake decreased and the normal daily weight gain stopped. This rebound is only indirectly related to NPY. Chronic (7-day long) i.c.v. NPY infusion induced an anabolic phase for 2-3 days, followed by a catabolic phase and fever, despite continued infusion. In cold-adaptation environment the primary metabolic effect of the infusion induced a moderate hypothermia with lower daytime nadirs and nocturnal peaks of the circadian temperature rhythm, while at near-thermoneutral environments in non-adapted rats the infusion attenuated only the nocturnal temperature rise by suppressing night-time hypermetabolism. Further finding is that in cold-adapted animals, the early feeding effect of NPY-infusion was enhanced, whereas the early hypothermic effect in cold was limited by interference with competing thermoregulatory mechanisms.
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Affiliation(s)
- M Székely
- Department of Pathophysiology, Faculty of Medicine, University of Pécs, 12 Szigeti ut, Pecs H-7624, Hungary.
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