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Mavanji V, Pomonis BL, Shekels L, Kotz CM. Interactions between Lateral Hypothalamic Orexin and Dorsal Raphe Circuitry in Energy Balance. Brain Sci 2024; 14:464. [PMID: 38790443 PMCID: PMC11117928 DOI: 10.3390/brainsci14050464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/30/2024] [Accepted: 05/04/2024] [Indexed: 05/26/2024] Open
Abstract
Orexin/hypocretin terminals innervate the dorsal raphe nucleus (DRN), which projects to motor control areas important for spontaneous physical activity (SPA) and energy expenditure (EE). Orexin receptors are expressed in the DRN, and obesity-resistant (OR) rats show higher expression of these receptors in the DRN and elevated SPA/EE. We hypothesized that orexin-A in the DRN enhances SPA/EE and that DRN-GABA modulates the effect of orexin-A on SPA/EE. We manipulated orexin tone in the DRN either through direct injection of orexin-A or through the chemogenetic activation of lateral-hypothalamic (LH) orexin neurons. In the orexin neuron activation experiment, fifteen minutes prior to the chemogenetic activation of orexin neurons, the mice received either the GABA-agonist muscimol or antagonist bicuculline injected into the DRN, and SPA/EE was monitored for 24 h. In a separate experiment, orexin-A was injected into the DRN to study the direct effect of DRN orexin on SPA/EE. We found that the activation of orexin neurons elevates SPA/EE, and manipulation of GABA in the DRN does not alter the SPA response to orexin neuron activation. Similarly, intra-DRN orexin-A enhanced SPA and EE in the mice. These results suggest that orexin-A in the DRN facilitates negative energy balance by increasing physical activity-induced EE, and that modulation of DRN orexin-A is a potential strategy to promote SPA and EE.
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Affiliation(s)
- Vijayakumar Mavanji
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brianna L. Pomonis
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Laurie Shekels
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Catherine M. Kotz
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
- Geriatric Research, Education and Clinical Center, Minneapolis VA Health Care System, Minneapolis, MN 55417, USA
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Choi PP, Wang Q, Brenner LA, Li AJ, Ritter RC, Appleyard SM. Lesion of NPY Receptor-expressing Neurons in Perifornical Lateral Hypothalamus Attenuates Glucoprivic Feeding. Endocrinology 2024; 165:bqae021. [PMID: 38368624 PMCID: PMC11043786 DOI: 10.1210/endocr/bqae021] [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] [Received: 06/07/2023] [Revised: 01/19/2024] [Accepted: 02/15/2024] [Indexed: 02/20/2024]
Abstract
Glucoprivic feeding is one of several counterregulatory responses (CRRs) that facilitates restoration of euglycemia following acute glucose deficit (glucoprivation). Our previous work established that glucoprivic feeding requires ventrolateral medullary (VLM) catecholamine (CA) neurons that coexpress neuropeptide Y (NPY). However, the connections by which VLM CA/NPY neurons trigger increased feeding are uncertain. We have previously shown that glucoprivation, induced by an anti-glycolygic agent 2-deoxy-D-glucose (2DG), activates perifornical lateral hypothalamus (PeFLH) neurons and that expression of NPY in the VLM CA/NPY neurons is required for glucoprivic feeding. We therefore hypothesized that glucoprivic feeding and possibly other CRRs require NPY-sensitive PeFLH neurons. To test this, we used the ribosomal toxin conjugate NPY-saporin (NPY-SAP) to selectively lesion NPY receptor-expressing neurons in the PeFLH of male rats. We found that NPY-SAP destroyed a significant number of PeFLH neurons, including those expressing orexin, but not those expressing melanin-concentrating hormone. The PeFLH NPY-SAP lesions attenuated 2DG-induced feeding but did not affect 2DG-induced increase in locomotor activity, sympathoadrenal hyperglycemia, or corticosterone release. The 2DG-induced feeding response was also significantly attenuated in NPY-SAP-treated female rats. Interestingly, PeFLH NPY-SAP lesioned male rats had reduced body weights and decreased dark cycle feeding, but this effect was not seen in female rats. We conclude that a NPY projection to the PeFLH is necessary for glucoprivic feeding, but not locomotor activity, hyperglycemia, or corticosterone release, in both male and female rats.
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Affiliation(s)
- Pique P Choi
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
| | - Qing Wang
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
| | - Lynne A Brenner
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
| | - Ai-Jun Li
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
| | - Robert C Ritter
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
| | - Suzanne M Appleyard
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
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Braine A, Georges F. Emotion in action: When emotions meet motor circuits. Neurosci Biobehav Rev 2023; 155:105475. [PMID: 37996047 DOI: 10.1016/j.neubiorev.2023.105475] [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: 07/28/2023] [Revised: 11/15/2023] [Accepted: 11/17/2023] [Indexed: 11/25/2023]
Abstract
The brain is a remarkably complex organ responsible for a wide range of functions, including the modulation of emotional states and movement. Neuronal circuits are believed to play a crucial role in integrating sensory, cognitive, and emotional information to ultimately guide motor behavior. Over the years, numerous studies employing diverse techniques such as electrophysiology, imaging, and optogenetics have revealed a complex network of neural circuits involved in the regulation of emotional or motor processes. Emotions can exert a substantial influence on motor performance, encompassing both everyday activities and pathological conditions. The aim of this review is to explore how emotional states can shape movements by connecting the neural circuits for emotional processing to motor neural circuits. We first provide a comprehensive overview of the impact of different emotional states on motor control in humans and rodents. In line with behavioral studies, we set out to identify emotion-related structures capable of modulating motor output, behaviorally and anatomically. Neuronal circuits involved in emotional processing are extensively connected to the motor system. These circuits can drive emotional behavior, essential for survival, but can also continuously shape ongoing movement. In summary, the investigation of the intricate relationship between emotion and movement offers valuable insights into human behavior, including opportunities to enhance performance, and holds promise for improving mental and physical health. This review integrates findings from multiple scientific approaches, including anatomical tracing, circuit-based dissection, and behavioral studies, conducted in both animal and human subjects. By incorporating these different methodologies, we aim to present a comprehensive overview of the current understanding of the emotional modulation of movement in both physiological and pathological conditions.
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Affiliation(s)
- Anaelle Braine
- Univ. Bordeaux, CNRS, IMN, UMR 5293, F-33000 Bordeaux, France
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Kolmos MG, Arribas AP, Kornum BR, Justinussen JL. Experimental sickness reduces hypocretin receptor 1 expression in the lateral hypothalamus and ventral tegmental area of female mice. Eur J Neurosci 2023; 58:4002-4010. [PMID: 37818927 DOI: 10.1111/ejn.16151] [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: 04/28/2023] [Revised: 08/23/2023] [Accepted: 09/11/2023] [Indexed: 10/13/2023]
Abstract
Recent studies have focused on how sickness behaviours, including lethargy, are coordinated in the brain in response to peripheral infections. Decreased hypocretin (orexin) signalling is associated with lethargy and previous research suggests that hypocretin signalling is downregulated during sickness. However, there are studies that find increases or no change in hypocretin signalling during sickness. It is further unknown whether hypocretin receptor expression changes during sickness. Using lipopolysaccharide (LPS) to induce sickness in female mice, we investigated how LPS-injection affects gene expression of hypocretin receptors and prepro-hypocretin as well as hypocretin-1 peptide concentrations in brain tissue. We found that hypocretin receptor 1 gene expression was downregulated during sickness in the lateral hypothalamus and ventral tegmental area, but not in the dorsal raphe nucleus or locus coeruleus. We found no changes in hypocretin receptor 2 expression. Using a gene expression calculation that accounts for primer efficiencies and multiple endogenous controls, we were unable to detect changes in prepro-hypocretin expression. Using radioimmunoassay, we found no change in hypocretin-1 peptide in rostral brain tissue. Our results indicate that hypocretin receptor expression can fluctuate during sickness, adding an additional level of complexity to understanding hypocretin signalling during sickness.
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Affiliation(s)
- Mie Gunni Kolmos
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alba Pérez Arribas
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Birgitte Rahbek Kornum
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jessica Lauren Justinussen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Levine JA. The Fidget Factor and the obesity paradox. How small movements have big impact. Front Sports Act Living 2023; 5:1122938. [PMID: 37077429 PMCID: PMC10106700 DOI: 10.3389/fspor.2023.1122938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 02/24/2023] [Indexed: 04/05/2023] Open
Abstract
The hypothesis is that the Fidget Factor is the innate neurological pulse that propels humans and other species to move to support their health. Fidgets, previously thought to be spontaneous, are neurologically regulated and highly ordered (non-random). Modern societies being chair-based overwhelm Fidget Factor pulses and consequently inflict chair-based living for transportation, labor, and leisure. Despite impulses firing through the nervous system, people sit because environmental design overwhelms the biology. Urbanization and chair-based societies were designed after the industrial revolution to promote productivity; however, the consequence has been opposite. Crushing the natural urge to move—the Fidget Factor—is a public health calamity. Excess sitting is associated with a myriad of detrimental health consequences and impairs productivity. Fidgeting may reduce all-cause mortality associated with excessive sitting. The Fidget Factor offers hope; data demonstrate that workplaces and schools can be designed to promote activity and free people's Fidget Factors. Evidence shows that people are happier, healthier, wealthier, and more successful if their Fidget Factors are freed.
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Schéle E, Stoltenborg I, Xie A, Peris-Sampedro F, Adan RAH, Dickson SL. Engagement of the brain orexin system in activity-based anorexia behaviour in mice. Eur Neuropsychopharmacol 2023; 70:63-71. [PMID: 36889178 DOI: 10.1016/j.euroneuro.2023.02.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 01/24/2023] [Accepted: 02/15/2023] [Indexed: 03/08/2023]
Abstract
While excessive physical activity is common amongst anorexia nervosa (AN) patients, contributing to their low body weight, little is known about the underlying biology and effective treatments targeting the hyperactivity are lacking. Given the role of orexin in arousal, physical activity and energy expenditure, we sought to investigate i) the extent to which orexin neurons are activated during severe anorectic state in the activity-based anorexia (ABA) mouse model, and ii) if the dual orexin receptor antagonist suvorexant can reduce physical activity during ABA. The Fos-TRAP2 technique enable us to visually capture active neurons (Fos expressing) during severe anorectic state in the ABA mouse model, and by immunohistochemistry, determine the extent to which these active neurons are orexin positive. In addition, suvorexant was administered peripherally to ABA mice and running activity was monitored. We found that a large population of orexin neurons in the hypothalamus are activated by ABA and that peripheral administration of suvorexant decreases food anticipatory activity in these mice. We conclude that orexin may be a suitable target to treat hyperactivity in AN and recommend further studies to examine the efficacy of suvorexant in aiding AN patients to control their drive for hyperactivity.
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Affiliation(s)
- Erik Schéle
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden.
| | - Iris Stoltenborg
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Anders Xie
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Fiona Peris-Sampedro
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Roger A H Adan
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht and Utrecht University, 3584 CJ Utrecht, The Netherlands
| | - Suzanne L Dickson
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden
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Muacevic A, Adler JR. Physiological Role of Orexin/Hypocretin in the Human Body in Motivated Behavior: A Comprehensive Review. Cureus 2023; 15:e34009. [PMID: 36814741 PMCID: PMC9939734 DOI: 10.7759/cureus.34009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 01/20/2023] [Indexed: 01/22/2023] Open
Abstract
Neurohormones are neurosecretory materials released by neurosecretory cells that serve both as neuromodulators in the brain and spinal cord and as circulating regulatory hormones. They serve a wide range of functions, including homeostasis, development, and modulation of neuronal and muscle activity. In the hypothalamus, neurohormones called hypocretins are created that were discovered in the late nineties. Orexin receptors (OXRs) have been shown to enhance synaptic signaling in the central nervous system at the cellular level. The orexins improve stimulated neural activity in the hippocampus, which, in turn, aids with spatial memory, learning, and mood. They present themselves as mediators for the hypothalamic functions. They have been shown to regulate sleep-wake cycles, arousal mechanisms, addiction, sympathetic nerve activity (SNA), blood pressure, and thermogenesis. Its role in storing brown adipose tissue has implications for thermal homeostasis. The significant role of orexins is seen in tumorigenesis when orexin A (OrxA) and orexin B (OrxB) induce apoptosis in fast-growing tumor cells. Orexin-null subjects show clinical narcolepsy, indicating that orexins were responsible for keeping them awake. Orexin microinjections in mice brains stimulated increased physical activity, thus possibly countering diet-induced obesity. Physical activity significantly increased plasma orexin-A levels, which facilitated the process of energy homeostasis. The amount of adrenocorticotropic hormone (ACTH) increases in stress conditions, which further facilitates the release of the stress hormone cortisol. No increase in the ACTH hormone is seen in stressed mice administered with orexin receptor 2 (OX2R) antagonists thus showing orexin's role in stress reaction. As a result of linking hypocretin/orexin to various physiological procedures, increased research into the medicinal potential of drugs targeting these receptors is emerging. We summed up in this review the recent advances in our understanding of how orexin and its receptor system play an essential role in clinical and pathological functions. This research summarizes a new area for research in human medicine, providing the possibility of controlling a vast array of physiological functions through intra-cerebroventricular injections of a single neuropeptide.
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Fu CW, Horng JL, Chou MY. Fish Behavior as a Neural Proxy to Reveal Physiological States. Front Physiol 2022; 13:937432. [PMID: 35910555 PMCID: PMC9326089 DOI: 10.3389/fphys.2022.937432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/23/2022] [Indexed: 11/13/2022] Open
Abstract
Behaviors are the integrative outcomes of the nervous system, which senses and responds to the internal physiological status and external stimuli. Teleosts are aquatic organisms which are more easily affected by the surrounding environment compared to terrestrial animals. To date, behavioral tests have been widely used to assess potential environmental risks using fish as model animals. In this review, we summarized recent studies regarding the effects of internal and external stimuli on fish behaviors. We concluded that behaviors reflect environmental and physiological changes, which have possible implications for environmental and physiological assessments.
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Affiliation(s)
- Chih-Wei Fu
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Ming-Yi Chou
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- *Correspondence: Ming-Yi Chou,
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Gao XB, Horvath TL. From Molecule to Behavior: Hypocretin/orexin Revisited From a Sex-dependent Perspective. Endocr Rev 2022; 43:743-760. [PMID: 34792130 PMCID: PMC9277634 DOI: 10.1210/endrev/bnab042] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Indexed: 11/19/2022]
Abstract
The hypocretin/orexin (Hcrt/Orx) system in the perifornical lateral hypothalamus has been recognized as a critical node in a complex network of neuronal systems controlling both physiology and behavior in vertebrates. Our understanding of the Hcrt/Orx system and its array of functions and actions has grown exponentially in merely 2 decades. This review will examine the latest progress in discerning the roles played by the Hcrt/Orx system in regulating homeostatic functions and in executing instinctive and learned behaviors. Furthermore, the gaps that currently exist in our knowledge of sex-related differences in this field of study are discussed.
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Affiliation(s)
- Xiao-Bing Gao
- Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Tamas L Horvath
- Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
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10
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Tran LT, Park S, Kim SK, Lee JS, Kim KW, Kwon O. Hypothalamic control of energy expenditure and thermogenesis. Exp Mol Med 2022; 54:358-369. [PMID: 35301430 PMCID: PMC9076616 DOI: 10.1038/s12276-022-00741-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 12/05/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022] Open
Abstract
Energy expenditure and energy intake need to be balanced to maintain proper energy homeostasis. Energy homeostasis is tightly regulated by the central nervous system, and the hypothalamus is the primary center for the regulation of energy balance. The hypothalamus exerts its effect through both humoral and neuronal mechanisms, and each hypothalamic area has a distinct role in the regulation of energy expenditure. Recent studies have advanced the understanding of the molecular regulation of energy expenditure and thermogenesis in the hypothalamus with targeted manipulation techniques of the mouse genome and neuronal function. In this review, we elucidate recent progress in understanding the mechanism of how the hypothalamus affects basal metabolism, modulates physical activity, and adapts to environmental temperature and food intake changes. The hypothalamus is a key regulator of metabolism, controlling resting metabolism, activity levels, and responses to external temperature and food intake. The balance between energy intake and expenditure must be tightly controlled, with imbalances resulting in metabolic disorders such as obesity or diabetes. Obin Kwon at Seoul National University College of Medicine and Ki Woo Kim at Yonsei University College of Dentistry, Seoul, both in South Korea, and coworkers reviewed how metabolism is regulated by the hypothalamus, a small hormone-producing brain region. They report that hormonal and neuronal signals from the hypothalamus influence the ratio of lean to fatty tissue, gender-based differences in metabolism, activity levels, and weight gain in response to food intake. They note that further studies to untangle cause-and-effect relationships and other genetic factors will improve our understanding of metabolic regulation.
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Affiliation(s)
- Le Trung Tran
- Departments of Oral Biology and Applied Biological Science, BK21 Four, Yonsei University College of Dentistry, Seoul, 03722, Korea
| | - Sohee Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Korea.,Departments of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, 03080, Korea
| | - Seul Ki Kim
- Departments of Oral Biology and Applied Biological Science, BK21 Four, Yonsei University College of Dentistry, Seoul, 03722, Korea
| | - Jin Sun Lee
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Korea.,Departments of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, 03080, Korea
| | - Ki Woo Kim
- Departments of Oral Biology and Applied Biological Science, BK21 Four, Yonsei University College of Dentistry, Seoul, 03722, Korea.
| | - Obin Kwon
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Korea. .,Departments of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, 03080, Korea.
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Mavanji V, Pomonis B, Kotz CM. Orexin, serotonin, and energy balance. WIREs Mech Dis 2022; 14:e1536. [PMID: 35023323 PMCID: PMC9286346 DOI: 10.1002/wsbm.1536] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/27/2021] [Accepted: 08/23/2021] [Indexed: 12/02/2022]
Abstract
The lateral hypothalamus is critical for the control of ingestive behavior and spontaneous physical activity (SPA), as lesion or stimulation of this region alters these behaviors. Evidence points to lateral hypothalamic orexin neurons as modulators of feeding and SPA. These neurons affect a broad range of systems, and project to multiple brain regions such as the dorsal raphe nucleus, which contains serotoninergic neurons (DRN) important to energy homeostasis. Physical activity is comprised of intentional exercise and SPA. These are opposite ends of a continuum of physical activity intensity and structure. Non‐goal‐oriented behaviors, such as fidgeting, standing, and ambulating, constitute SPA in humans, and reflect a propensity for activity separate from intentional activity, such as high‐intensity voluntary exercise. In animals, SPA is activity not influenced by rewards such as food or a running wheel. Spontaneous physical activity in humans and animals burns calories and could theoretically be manipulated pharmacologically to expend calories and protect against obesity. The DRN neurons receive orexin inputs, and project heavily onto cortical and subcortical areas involved in movement, feeding and energy expenditure (EE). This review discusses the function of hypothalamic orexin in energy‐homeostasis, the interaction with DRN serotonin neurons, and the role of this orexin‐serotonin axis in regulating food intake, SPA, and EE. In addition, we discuss possible brain areas involved in orexin–serotonin cross‐talk; the role of serotonin receptors, transporters and uptake‐inhibitors in the pathogenesis and treatment of obesity; animal models of obesity with impaired serotonin‐function; single‐nucleotide polymorphisms in the serotonin system and obesity; and future directions in the orexin–serotonin field. This article is categorized under:Metabolic Diseases > Molecular and Cellular Physiology
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Affiliation(s)
- Vijayakumar Mavanji
- Research Service, Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
| | - Brianna Pomonis
- Research Service, Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
| | - Catherine M Kotz
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota, USA.,Geriatric Research Education and Clinical Center, Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
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12
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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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Aerobic training associated with an active lifestyle exerts a protective effect against oxidative damage in hypothalamus and liver: The involvement of energy metabolism. Brain Res Bull 2021; 175:116-129. [PMID: 34303768 DOI: 10.1016/j.brainresbull.2021.07.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/24/2021] [Accepted: 07/20/2021] [Indexed: 12/27/2022]
Abstract
BACKGROUND Oxidation resistance protein 1 (OXR1) is of scientific interest due its role in protecting tissues against oxidative stress, DNA mutations and tumorigenesis, but little is known regarding strategies to increase OXR1 in different tissues. As an improved antioxidant defense may result from a high total amount of physical activity, the present study was designed to determine whether an active lifestyle including aerobic training exercise and spontaneous physical activity (SPA) can increase OXR1. We have built a large cage (LC) that allows animals to move freely, promoting an increase in SPA in comparison to a small cage (SC). METHODS We examined the effects of aerobic training applied for 8 weeks on SPA and OXR1 of C57BL/6 J mice living in two types of housing (SC and LC). OXR1 protein was studied in hypothalamus, muscle and liver, which were chosen due to their important role in energy and metabolic homeostasis. RESULTS LC-mice were more active than SC-mice as determined by SPA values. Despite both trained groups exhibiting similar gains in aerobic capacity, only trained mice kept in a large cage (but not for trained mice housed in SC) exhibited high OXR1 in the hypothalamus and liver. Trained mice housed in LC that exhibited an up-regulation of OXR1 also were those who exhibited an energy-expensive metabolism (based on metabolic parameters). CONCLUSIONS These results suggest that aerobic training associated with a more active lifestyle exerts a protective effect against oxidative damage and may be induced by changes in energy metabolism.
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14
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Muthmainah M, Gogos A, Sumithran P, Brown RM. Orexins (hypocretins): The intersection between homeostatic and hedonic feeding. J Neurochem 2021; 157:1473-1494. [PMID: 33608877 DOI: 10.1111/jnc.15328] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 02/11/2021] [Accepted: 02/15/2021] [Indexed: 12/11/2022]
Abstract
Orexins are hypothalamic neuropeptides originally discovered to play a role in the regulation of feeding behaviour. The broad connections of orexin neurons to mesocorticolimbic circuitry suggest they may play a role in mediating reward-related behaviour beyond homeostatic feeding. Here, we review the role of orexin in a variety of eating-related behaviour, with a focus on reward and motivation, and the neural circuits driving these effects. One emerging finding is the involvement of orexins in hedonic and appetitive behaviour towards palatable food, in addition to their role in homeostatic feeding. This review discusses the brain circuitry and possible mechanisms underlying the role of orexins in these behaviours. Overall, there is a marked bias in the literature towards studies involving male subjects. As such, future work needs to be done to involve female subjects. In summary, orexins play an important role in driving motivation for high salient rewards such as highly palatable food and may serve as the intersection between homeostatic and hedonic feeding.
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Affiliation(s)
- Muthmainah Muthmainah
- The Florey Institute of Neuroscience and Mental Health, Mental Health Research Theme, Parkville, Melbourne, Vic., Australia.,The Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Vic., Australia.,Department of Anatomy, Faculty of Medicine, Universitas Sebelas Maret, Surakarta, Indonesia
| | - Andrea Gogos
- The Florey Institute of Neuroscience and Mental Health, Mental Health Research Theme, Parkville, Melbourne, Vic., Australia
| | - Priya Sumithran
- Department of Medicine (Austin), University of Melbourne, Heidelberg, Vic., Australia.,Department of Endocrinology, Austin Health, Heidelberg, Vic., Australia
| | - Robyn M Brown
- The Florey Institute of Neuroscience and Mental Health, Mental Health Research Theme, Parkville, Melbourne, Vic., Australia.,The Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Vic., Australia
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15
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Williams DL, Coiduras II, Parise EM, Maske CB. Hindbrain orexin 1 receptors blunt intake suppression by gastrointestinal nutrients and cholecystokinin in male rats. Peptides 2020; 133:170351. [PMID: 32579900 PMCID: PMC7556705 DOI: 10.1016/j.peptides.2020.170351] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/19/2020] [Accepted: 06/19/2020] [Indexed: 01/06/2023]
Abstract
Hypothalamic orexin neurons project to many brain areas, including hindbrain structures such as the nucleus of the solitary tract (NTS) and area postrema (AP), where orexin 1 receptors (OX1Rs) are expressed. Hindbrain administration of orexin-A increases feeding and meal size, and blockade of hindbrain OX1Rs with the selective antagonist SB334867 has the opposite effect. Here we asked whether hindbrain OX1R stimulation or blockade alter rats' sensitivity to gastrointestinal satiety signals. Rats received 4th intracerebroventricular (icv) injections of vehicle or orexin-A, at a dose with no effect on its own, prior to an intragastric (IG) infusion of saline or a satiating volume of Ensure. IG Ensure suppressed subsequent chow intake, but orexin-A pretreatment significantly attenuated this IG nutrient-induced satiety at 2 h into the dark phase. In a second experiment, rats received NTS injections of vehicle or orexin-A before intraperitoneal (IP) injection of vehicle or the satiation hormone cholecystokinin (CCK). NTS orexin-A pretreatment completely blocked the intake-suppressive effect of CCK on dark-phase chow intake. Finally, we investigated the role of endogenous hindbrain OX1R activation by pretreating rats with 4th-icv injection of vehicle or SB334867 followed by IG infusion of saline or Ensure just before a chocolate Ensure licking test session. IG nutrient infusion suppressed Ensure intake, and blockade of hindbrain OX1Rs significantly prolonged that intake-suppressive effect. We conclude that hindbrain OX1Rs are a mechanism though which hypothalamic orexin neurons can reduce animals' sensitivity to gastrointestinal nutrient load, allowing them to consume more food.
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Affiliation(s)
- Diana L Williams
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL, 32306-4301 USA.
| | - Isabel I Coiduras
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL, 32306-4301 USA
| | - Eric M Parise
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL, 32306-4301 USA
| | - Calyn B Maske
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL, 32306-4301 USA
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16
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Lee J, Raycraft L, Johnson AW. The dynamic regulation of appetitive behavior through lateral hypothalamic orexin and melanin concentrating hormone expressing cells. Physiol Behav 2020; 229:113234. [PMID: 33130035 DOI: 10.1016/j.physbeh.2020.113234] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 02/07/2023]
Abstract
The lateral hypothalamic area (LHA) is a heterogeneous brain structure extensively studied for its potent role in regulating energy balance. The anatomical and molecular diversity of the LHA permits the orchestration of responses to energy sensing cues from the brain and periphery. Two of the primary cell populations within the LHA associated with integration of this information are Orexin (ORX) and Melanin Concentrating Hormone (MCH). While both of these non-overlapping populations exhibit orexigenic properties, the activities of these two systems support feeding behavior through contrasting mechanisms. We describe the anatomical and functional properties as well as interaction with other neuropeptides and brain reward and hedonic systems. Specific outputs relating to arousal, food seeking, feeding, and metabolism are coordinated through these mechanisms. We then discuss how both the ORX and MCH systems harmonize in a divergent yet overall cooperative manner to orchestrate feeding behavior through transitions between various appetitive states, and thus offer novel insights into LHA allostatic control of appetite.
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Affiliation(s)
| | | | - Alexander W Johnson
- Department of Psychology; Neuroscience Program, Michigan State University, East Lansing.
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17
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Valenzano A, Tartaglia N, Ambrosi A, Tafuri D, Monda M, Messina A, Sessa F, Campanozzi A, Monda V, Cibelli G, Messina G, Polito R. The Metabolic Rearrangements of Bariatric Surgery: Focus on Orexin-A and the Adiponectin System. J Clin Med 2020; 9:jcm9103327. [PMID: 33081283 PMCID: PMC7602946 DOI: 10.3390/jcm9103327] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/07/2020] [Accepted: 10/10/2020] [Indexed: 12/28/2022] Open
Abstract
The accumulation of adipose tissue represents one of the characteristics of obesity, increasing the risk of developing correlated obesity diseases such as cardiovascular disease, type 2 diabetes, cancer, and immune diseases. Visceral adipose tissue accumulation leads to chronic low inflammation inducing an imbalanced adipokine secretion. Among these adipokines, Adiponectin is an important metabolic and inflammatory mediator. It is also known that adipose tissue is influenced by Orexin-A levels, a neuropeptide produced in the lateral hypothalamus. Adiponectin and Orexin-A are strongly decreased in obesity and are associated with metabolic and inflammatory pathways. The aim of this review was to investigate the involvement of the autonomic nervous system focusing on Adiponectin and Orexin-A after bariatric surgery. After bariatric surgery, Adiponectin and Orexin-A levels are strongly increased independently of weight loss showing that hormone increases are also attributable to a rearrangement of metabolic and inflammatory mediators. The restriction of food intake and malabsorption are not sufficient to clarify the clinical effects of bariatric surgery suggesting the involvement of neuro-hormonal feedback loops and also of mediators such as Adiponectin and Orexin-A.
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Affiliation(s)
- Anna Valenzano
- Department of Clinical and Experimental Medicine, University of Foggia, 71100 Foggia, Italy; (A.V.); (F.S.); (G.C.)
| | - Nicola Tartaglia
- General Surgery, Department of Medical and Surgical Sciences, University of Foggia, 71100 Foggia, Italy; (N.T.); (A.A.)
| | - Antonio Ambrosi
- General Surgery, Department of Medical and Surgical Sciences, University of Foggia, 71100 Foggia, Italy; (N.T.); (A.A.)
| | - Domenico Tafuri
- Department of Motor Sciences and Wellness, University of Naples “Parthenope”, 80133 Naples, Italy;
| | - Marcellino Monda
- Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetic and Sport Medicine, Università degli Studi della Campania Luigi Vanvitelli, 80138 Naples, Italy; (M.M.); (A.M.); (V.M.)
| | - Antonietta Messina
- Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetic and Sport Medicine, Università degli Studi della Campania Luigi Vanvitelli, 80138 Naples, Italy; (M.M.); (A.M.); (V.M.)
| | - Francesco Sessa
- Department of Clinical and Experimental Medicine, University of Foggia, 71100 Foggia, Italy; (A.V.); (F.S.); (G.C.)
| | - Angelo Campanozzi
- Pediatrics, Department of Medical and Surgical Sciences, University of Foggia, 71100 Foggia, Italy;
| | - Vincenzo Monda
- Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetic and Sport Medicine, Università degli Studi della Campania Luigi Vanvitelli, 80138 Naples, Italy; (M.M.); (A.M.); (V.M.)
| | - Giuseppe Cibelli
- Department of Clinical and Experimental Medicine, University of Foggia, 71100 Foggia, Italy; (A.V.); (F.S.); (G.C.)
| | - Giovanni Messina
- Department of Clinical and Experimental Medicine, University of Foggia, 71100 Foggia, Italy; (A.V.); (F.S.); (G.C.)
- Correspondence: (G.M.); (R.P.); Tel.: +39-0881588095 (G.M.)
| | - Rita Polito
- Department of Clinical and Experimental Medicine, University of Foggia, 71100 Foggia, Italy; (A.V.); (F.S.); (G.C.)
- Correspondence: (G.M.); (R.P.); Tel.: +39-0881588095 (G.M.)
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18
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Polito R, Monda V, Nigro E, Messina A, Di Maio G, Giuliano MT, Orrù S, Imperlini E, Calcagno G, Mosca L, Mollica MP, Trinchese G, Scarinci A, Sessa F, Salerno M, Marsala G, Buono P, Mancini A, Monda M, Daniele A, Messina G. The Important Role of Adiponectin and Orexin-A, Two Key Proteins Improving Healthy Status: Focus on Physical Activity. Front Physiol 2020; 11:356. [PMID: 32390865 PMCID: PMC7188914 DOI: 10.3389/fphys.2020.00356] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 03/27/2020] [Indexed: 12/15/2022] Open
Abstract
Exercise represents the most important integrative therapy in metabolic, immunologic and chronic diseases; it represents a valid strategy in the non-pharmacological intervention of lifestyle linked diseases. A large body of evidence indicates physical exercise as an effective measure against chronic non-communicable diseases. The worldwide general evidence for health benefits are both for all ages and skill levels. In a dysregulated lifestyle such as in the obesity, there is an imbalance in the production of different cytokines. In particular, we focused on Adiponectin, an adipokine producted by adipose tissue, and on Orexin-A, a neuropeptide synthesized in the lateral hypothalamus. The production of both Adiponectin and Orexin-A increases following regular and structured physical activity and both these hormones have similar actions. Indeed, they improve energy and glucose metabolism, and also modulate energy expenditure and thermogenesis. In addition, a relevant biological role of Adiponectin and Orexin A has been recently highlighted in the immune system, where they function as immune-suppressor factors. The strong connection between these two cytokines and healthy status is mediated by physical activity and candidates these hormones as potential biomarkers of the beneficial effects induced by physical activity. For these reasons, this review aims to underly the interconnections among Adiponectin, Orexin-A, physical activity and healthy status. Furthermore, it is analyzed the involvement of Adiponectin and Orexin-A in physical activity as physiological factors improving healthy status through physical exercise.
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Affiliation(s)
- Rita Polito
- Dipartimento di Scienze e Tecnologie Ambientali Biologiche e Farmaceutiche, University of Campania "Luigi Vanvitelli", Caserta, Italy.,Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
| | - Vincenzo Monda
- Dipartimento di Medicina Sperimentale, Sezione di Fisiologia Umana e Unità di Dietetica e Medicina dello Sport, Università degli Studi della Campania "Luigi Vanvitelli", Naples, Italy
| | - Ersilia Nigro
- Dipartimento di Scienze e Tecnologie Ambientali Biologiche e Farmaceutiche, University of Campania "Luigi Vanvitelli", Caserta, Italy.,Ceinge Biotecnologie Avanzate S. C. a R. L., Naples, Italy
| | - Antonietta Messina
- Dipartimento di Medicina Sperimentale, Sezione di Fisiologia Umana e Unità di Dietetica e Medicina dello Sport, Università degli Studi della Campania "Luigi Vanvitelli", Naples, Italy
| | - Girolamo Di Maio
- Dipartimento di Medicina Sperimentale, Sezione di Fisiologia Umana e Unità di Dietetica e Medicina dello Sport, Università degli Studi della Campania "Luigi Vanvitelli", Naples, Italy
| | - Maria Teresa Giuliano
- Dipartimento di Medicina Sperimentale, Sezione di Fisiologia Umana e Unità di Dietetica e Medicina dello Sport, Università degli Studi della Campania "Luigi Vanvitelli", Naples, Italy
| | - Stefania Orrù
- Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli "Parthenope", Naples, Italy.,IRCCS SDN, Naples, Italy
| | | | - Giuseppe Calcagno
- Dipartimento di Medicina e Scienze della Salute "Vincenzo Tiberio", Università degli Studi del Molise, Campobasso, Italy
| | - Laura Mosca
- Dipartimento di Biologia, Universitá degli studi di Napoli Federico II, Naples, Italy
| | - Maria Pina Mollica
- Dipartimento di Biologia, Universitá degli studi di Napoli Federico II, Naples, Italy
| | - Giovanna Trinchese
- Dipartimento di Biologia, Universitá degli studi di Napoli Federico II, Naples, Italy
| | - Alessia Scarinci
- Dipartimento di Scienze della Formazione, Psicologia, Comunicazione, Università degli Studi di Bari Aldo Moro, Bari, Italy
| | - Francesco Sessa
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
| | - Monica Salerno
- Department of Medical, Surgery Sciences and Advanced Technologies "G.F. Ingrassia", University of Catania, Catania, Italy
| | - Gabriella Marsala
- Struttura Complessa di Farmacia, Azienda Ospedaliero Universitaria - Ospedali Riuniti, Foggia, Italy
| | - Pasqualina Buono
- Ceinge Biotecnologie Avanzate S. C. a R. L., Naples, Italy.,Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli "Parthenope", Naples, Italy.,IRCCS SDN, Naples, Italy
| | - Annamaria Mancini
- Ceinge Biotecnologie Avanzate S. C. a R. L., Naples, Italy.,Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli "Parthenope", Naples, Italy
| | - Marcellino Monda
- Dipartimento di Medicina Sperimentale, Sezione di Fisiologia Umana e Unità di Dietetica e Medicina dello Sport, Università degli Studi della Campania "Luigi Vanvitelli", Naples, Italy
| | - Aurora Daniele
- Dipartimento di Scienze e Tecnologie Ambientali Biologiche e Farmaceutiche, University of Campania "Luigi Vanvitelli", Caserta, Italy.,Ceinge Biotecnologie Avanzate S. C. a R. L., Naples, Italy
| | - Giovanni Messina
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
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19
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Hou Y, Liu Y, Liu C, Yan Z, Ma Q, Chen J, Zhang M, Yan Q, Li X, Chen J. Xiaoyaosan regulates depression‐related behaviors with physical symptoms by modulating Orexin A/OxR1 in the hypothalamus. Anat Rec (Hoboken) 2020; 303:2144-2153. [DOI: 10.1002/ar.24386] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 12/18/2019] [Accepted: 01/07/2020] [Indexed: 12/31/2022]
Affiliation(s)
- Yajing Hou
- School of Traditional Chinese Medicine Beijing University of Chinese Medicine Beijing China
| | - Yueyun Liu
- School of Traditional Chinese Medicine Beijing University of Chinese Medicine Beijing China
| | - Chenyue Liu
- School of Traditional Chinese Medicine Beijing University of Chinese Medicine Beijing China
| | - Zhiyi Yan
- School of Traditional Chinese Medicine Beijing University of Chinese Medicine Beijing China
| | - Qingyu Ma
- Formula‐pattern Research Center, School of Traditional Chinese Medicine Jinan University Guangzhou Guangdong China
| | - Jianbei Chen
- School of Traditional Chinese Medicine Beijing University of Chinese Medicine Beijing China
| | - Man Zhang
- School of Traditional Chinese Medicine Beijing University of Chinese Medicine Beijing China
| | - Qiuying Yan
- School of Traditional Chinese Medicine Beijing University of Chinese Medicine Beijing China
| | - Xiaojuan Li
- School of Traditional Chinese Medicine Beijing University of Chinese Medicine Beijing China
- Formula‐pattern Research Center, School of Traditional Chinese Medicine Jinan University Guangzhou Guangdong China
| | - Jiaxu Chen
- School of Traditional Chinese Medicine Beijing University of Chinese Medicine Beijing China
- Formula‐pattern Research Center, School of Traditional Chinese Medicine Jinan University Guangzhou Guangdong China
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20
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Effects of DCM Leaf Extract of Gnidia glauca (Fresen) on Locomotor Activity, Anxiety, and Exploration-Like Behaviors in High-Fat Diet-Induced Obese Rats. Behav Neurol 2019; 2019:7359235. [PMID: 31933694 PMCID: PMC6942765 DOI: 10.1155/2019/7359235] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 11/03/2019] [Accepted: 12/07/2019] [Indexed: 11/30/2022] Open
Abstract
Obesity is the main component of metabolic syndromes involving distinct etiologies that target different underlying behavioral and physiological functions within the brain structures and neuronal circuits. An alteration in the neuronal circuitry stemming from abdominal or central obesity stimulates a cascade of changes in neurochemical signaling that directly or indirectly mediate spontaneously emitted behaviors such as locomotor activity patterns, anxiety, and exploration. Pharmacological agents available for the treatment of neurologic disorders have been associated with limited potency and intolerable adverse effects. These have necessitated the upsurge in the utilization of herbal prescriptions due to their affordability and easy accessibility and are firmly embedded within wider belief systems of many people. Gnidia glauca has been used in the management of many ailments including obesity and associated symptomatic complications. However, its upsurge in use has not been accompanied by empirical determination of these folkloric claims. The present study, therefore, is aimed at determining the modulatory effects of dichloromethane leaf extract of Gnidia glauca on locomotor activity, exploration, and anxiety-like behaviors in high-fat diet-induced obese rats in an open-field arena. Obesity was experimentally induced by feeding the rats with prepared high-fat diet and water ad libitum for 6 weeks. The in vivo antiobesity effects were determined by oral administration of G. glauca at dosage levels of 200, 250, and 300 mg/kg body weight in high-fat diet-induced obese rats from the 6th to 12th week. Phytochemical analysis was done using gas chromatography linked to mass spectroscopy. Results indicated that Gnidia glauca showed anxiolytic effects and significantly increased spontaneous locomotor activity and exploration-like behaviors in HFD-induced obese rats. The plant extract also contained phytocompounds that have been associated with amelioration of the main neurodegenerative mediators, viz., inflammation and oxidative stress. These findings provide “qualified leads” for the synthesis of new alternative therapeutic agents for the management of neurologic disorders. However, there is a need to conduct toxicity studies of Gnidia glauca to establish its safety profiles.
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21
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Scariot PPM, Manchado-Gobatto FB, Prolla TA, Masselli Dos Reis IG, Gobatto CA. Housing conditions modulate spontaneous physical activity, feeding behavior, aerobic running capacity and adiposity in C57BL/6J mice. Horm Behav 2019; 115:104556. [PMID: 31310763 DOI: 10.1016/j.yhbeh.2019.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 07/11/2019] [Accepted: 07/12/2019] [Indexed: 11/19/2022]
Abstract
There is evidence of reduced adiposity in rodents living in a large cages (LC) as compared to animals housed in small cages (SC). Because spontaneous physical activity (SPA) provides an important portion of the total daily energy expenditure, an increase of SPA in rodents kept in LC could explain their reduced body fat accumulation. The relationship between SPA and components of physical fitness (i.e. aerobic and anaerobic fitness and body leanness) has not been previously determined. We examined the effects of eight weeks of LC exposure on SPA, body composition, feeding behavior, as well as aerobic and anaerobic running capacity in adult C57BL/6J mice. Male mice were housed in cages of two different sizes for 8 weeks: a small (SC, n = 10) and large (LC n = 10) cages with 1320 cm2 and 4800 cm2 floor space, respectively. SPA was measured gravimetrically, and food and water intake were recorded daily. Mice had critical velocity (CV) and anaerobic running capacity (ARC) evaluated at the beginning, middle course (4th week) and at the end of study (8th week). Despite non-significant differences in each week LC-mice were more active than SC-mice by considering all SPA values obtained in the entire period of 8 weeks. The difference in SPA over the whole day was mainly due to light phase activity, but also due to activity at dark period (from 6 pm to 9 pm and from 5 am to 6 am). LC-mice also exhibited higher food and water intake over the entire 8-wk period. LC-mice had lower content of fat mass (% of the eviscerated carcass) than SC-mice (SC: 8.4 ± 0.4 vs LC: 6.3 ± 0.3, p < 0.05). LC-mice also exhibited reduced epididymal fat pads (% of body mass) compared to SC-mice (SC: 1.3 ± 0.1 vs LC: 0.9 ± 0.1, p < 0.05) and retroperitoneal fat pads (SC: 0.4 ± 0.05 vs LC: 0.2 ± 0.02, p < 0.05). The LC-group showed significantly higher critical velocity than SC-group at the fourth week (SC: 14.9 ± 0.6 m·min-1 vs LC: 18.0 ± 0.3 m·min-1, p < 0.05) and eighth week (SC: 17.1 ± 0.5 m·min-1 vs LC: 18.8 ± 0.6 m·min-1, p < 0.05). Our findings demonstrate that eight weeks of LC housing increases SPA of C57BL/6J mice, and this may lead to reduced fat accumulation as well as higher aerobic fitness. Importantly, our study implies that SC limits SPA, possibly generating experimental artifacts in long-term rodent studies.
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Affiliation(s)
- Pedro Paulo Menezes Scariot
- School of Applied Sciences, University of Campinas, Laboratory of Applied Sport Physiology, Limeira, SP, Brazil
| | - Fúlvia B Manchado-Gobatto
- School of Applied Sciences, University of Campinas, Laboratory of Applied Sport Physiology, Limeira, SP, Brazil
| | - Tomas A Prolla
- Department of Genetics & Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Ivan G Masselli Dos Reis
- School of Applied Sciences, University of Campinas, Laboratory of Applied Sport Physiology, Limeira, SP, Brazil
| | - Claudio Alexandre Gobatto
- School of Applied Sciences, University of Campinas, Laboratory of Applied Sport Physiology, Limeira, SP, Brazil.
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22
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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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23
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Liu MF, Xue Y, Liu C, Liu YH, Diao HL, Wang Y, Pan YP, Chen L. Orexin-A Exerts Neuroprotective Effects via OX1R in Parkinson's Disease. Front Neurosci 2018. [PMID: 30524223 DOI: 10.3389/fnins.2018.00835.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Parkinson's disease (PD) is a common neurodegenerative disorder characterized by progressive and selective death of dopaminergic neurons. Orexin-A is involved in many biological effects of the body. It has been reported that orexin-A has protective effects in cellular models of PD. However, little is known about the protective effects of orexin-A in animal parkinsonian models and the cellular mechanism has not yet been fully clarified. The aim of this study was to evaluate the effects of orexin-A in MPTP mice model of PD as well as the possible neuroprotective mechanisms of orexin-A on dopaminergic neurons. The results from animal experiments demonstrated that orexin-A attenuated the loss of dopaminergic neurons and the decrease of tyrosine hydroxylase (TH) expression in the substantia nigra, normalized the striatal dopaminergic fibers, and prevented the depletion of dopamine and its metabolites in the striatum. MPTP-treated mice showed cognitive impairments accompanied with significant motor deficiency. Orexin-A improved MPTP-induced impairments in both motor activity and spatial memory. Importantly, orexin-A increased the protein level of brain-derived neurotrophic factor (BDNF) in dopaminergic neurons of the substantia nigra. Furthermore, the protective effects of orexin-A on MPTP parkinsonian mice could be blocked by orexinergic receptor 1 (OX1R) antagonist, SB334867. In another set of experiments with SH-SY5Y dopaminergic cells, orexin-A significantly induced the expression of BDNF in a dose and time-dependent manner. The upregulation of BDNF is mainly concerned with PI3K and PKC signaling pathways via OX1R. The present study demonstrated that orexin-A exerted neuroprotective effects on MPTP parkinsonian mice, which may imply orexin-A as a potential therapeutic target for PD.
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Affiliation(s)
- Mei-Fang Liu
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China.,College of Pharmacy, Jining Medical University, Rizhao, China
| | - Yan Xue
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Cui Liu
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Yun-Hai Liu
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Hui-Ling Diao
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Ying Wang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Yi-Peng Pan
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Lei Chen
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
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Liu MF, Xue Y, Liu C, Liu YH, Diao HL, Wang Y, Pan YP, Chen L. Orexin-A Exerts Neuroprotective Effects via OX1R in Parkinson's Disease. Front Neurosci 2018; 12:835. [PMID: 30524223 PMCID: PMC6262320 DOI: 10.3389/fnins.2018.00835] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/26/2018] [Indexed: 12/22/2022] Open
Abstract
Parkinson’s disease (PD) is a common neurodegenerative disorder characterized by progressive and selective death of dopaminergic neurons. Orexin-A is involved in many biological effects of the body. It has been reported that orexin-A has protective effects in cellular models of PD. However, little is known about the protective effects of orexin-A in animal parkinsonian models and the cellular mechanism has not yet been fully clarified. The aim of this study was to evaluate the effects of orexin-A in MPTP mice model of PD as well as the possible neuroprotective mechanisms of orexin-A on dopaminergic neurons. The results from animal experiments demonstrated that orexin-A attenuated the loss of dopaminergic neurons and the decrease of tyrosine hydroxylase (TH) expression in the substantia nigra, normalized the striatal dopaminergic fibers, and prevented the depletion of dopamine and its metabolites in the striatum. MPTP-treated mice showed cognitive impairments accompanied with significant motor deficiency. Orexin-A improved MPTP-induced impairments in both motor activity and spatial memory. Importantly, orexin-A increased the protein level of brain-derived neurotrophic factor (BDNF) in dopaminergic neurons of the substantia nigra. Furthermore, the protective effects of orexin-A on MPTP parkinsonian mice could be blocked by orexinergic receptor 1 (OX1R) antagonist, SB334867. In another set of experiments with SH-SY5Y dopaminergic cells, orexin-A significantly induced the expression of BDNF in a dose and time-dependent manner. The upregulation of BDNF is mainly concerned with PI3K and PKC signaling pathways via OX1R. The present study demonstrated that orexin-A exerted neuroprotective effects on MPTP parkinsonian mice, which may imply orexin-A as a potential therapeutic target for PD.
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Affiliation(s)
- Mei-Fang Liu
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China.,College of Pharmacy, Jining Medical University, Rizhao, China
| | - Yan Xue
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Cui Liu
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Yun-Hai Liu
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Hui-Ling Diao
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Ying Wang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Yi-Peng Pan
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Lei Chen
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
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25
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Abstract
The neuropeptides orexins are important in regulating the neurobiological systems that respond to stressful stimuli. Furthermore, orexins are known to play a role many of the phenotypes associated with stress-related mental illness such as changes in cognition, sleep-wake states, and appetite. Interestingly, orexins are altered in stress-related psychiatric disorders such as Major Depressive Disorder and Anxiety Disorders. Thus, orexins may be a potential target for treatment of these disorders. In this review, we will focus on what is known about the role of orexins in acute and repeated stress, in stress-induced phenotypes relevant to psychiatric illness in preclinical models, and in stress-related psychiatric illness in humans. We will also briefly discuss how orexins may contribute to sex differences in the stress response and subsequent phenotypes relevant to mental health, as many stress-related psychiatric disorders are twice as prevalent in women.
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26
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Barson JR. Orexin/hypocretin and dysregulated eating: Promotion of foraging behavior. Brain Res 2018; 1731:145915. [PMID: 30125533 DOI: 10.1016/j.brainres.2018.08.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/31/2018] [Accepted: 08/15/2018] [Indexed: 12/14/2022]
Abstract
At its discovery, orexin/hypocretin (OX) was hypothesized to promote food intake. Subsequently, with the identification of the participation of OX in numerous other phenomena, including arousal and drug seeking, this neuropeptide was proposed to be involved in highly motivated behaviors. The present review develops the hypothesis that the primary evolutionary function of OX is to promote foraging behavior, seeking for food under conditions of limited availability. Thus, it will first describe published literature on OX and homeostatic food intake, which shows that OX neurons are activated by conditions of food deprivation and in turn stimulate food intake. Next, it will present literature on excessive and binge-like food intake, which demonstrates that OX stimulates both intake and willingness to work for palatable food. Importantly, studies show that binge-like eating can be inhibited by OX antagonists at doses far lower than those required to suppress homeostatic intake (3 mg/kg vs. 30 mg/kg), suggesting that an OX-based pharmacotherapy, at the right dose, could specifically control dysregulated eating. Finally, the review will discuss the role of OX in foraging behavior, citing literature which shows that OX neurons, which are activated during the anticipation of food reward, can promote a number of phenomena involved in successful foraging, including food-anticipatory locomotor behavior, olfactory sensitivity, visual attention, spatial memory, and mastication. Thus, OX may promote homeostatic eating, as well as binge eating of palatable food, due to its ability to stimulate and coordinate the activities involved in foraging behavior.
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Affiliation(s)
- Jessica R Barson
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA.
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27
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Makarem N, Aggarwal B. Gender Differences in Associations between Insufficient Sleep and Cardiovascular Disease Risk Factors and Endpoints: A Contemporary Review. GENDER AND THE GENOME 2018. [DOI: 10.1089/gg.2017.0001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Nour Makarem
- Department of Medicine, Division of Cardiology, Columbia University Medical Center, New York, New York
| | - Brooke Aggarwal
- Department of Medicine, Division of Cardiology, Columbia University Medical Center, New York, New York
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28
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Grafe LA, Eacret D, Dobkin J, Bhatnagar S. Reduced Orexin System Function Contributes to Resilience to Repeated Social Stress. eNeuro 2018; 5:ENEURO.0273-17.2018. [PMID: 29662948 PMCID: PMC5900465 DOI: 10.1523/eneuro.0273-17.2018] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 01/31/2018] [Accepted: 02/05/2018] [Indexed: 12/12/2022] Open
Abstract
Exposure to stress increases the risk of developing affective disorders such as depression and post-traumatic stress disorder (PTSD). However, these disorders occur in only a subset of individuals, those that are more vulnerable to the effects of stress, whereas others remain resilient. The coping style adopted to deal with the stressor, either passive or active coping, is related to vulnerability or resilience, respectively. Important neural substrates that mediate responses to a stressor are the orexins. These neuropeptides are altered in the cerebrospinal fluid of patients with stress-related illnesses such as depression and PTSD. The present experiments used a rodent social defeat model that generates actively coping rats and passively coping rats, which we have previously shown exhibit resilient and vulnerable profiles, respectively, to examine if orexins play a role in these stress-induced phenotypes. In situ radiolabeling and qPCR revealed that actively coping rats expressed significantly lower prepro-orexin mRNA compared with passively coping rats. This led to the hypothesis that lower levels of orexins contribute to resilience to repeated social stress. To test this hypothesis, rats first underwent 5 d of social defeat to establish active and passive coping phenotypes. Then, orexin neurons were inhibited before each social defeat for three additional days using designer receptors exclusively activated by designer drugs (DREADDs). Inhibition of orexins increased social interaction behavior and decreased depressive-like behavior in the vulnerable population of rats. Indeed, these data suggest that lowering orexins promoted resilience to social defeat and may be an important target for treatment of stress-related disorders.
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Affiliation(s)
- Laura A. Grafe
- Department of Anesthesiology and Critical Care, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania 19104
| | - Darrell Eacret
- Department of Anesthesiology and Critical Care, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania 19104
| | - Jane Dobkin
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Seema Bhatnagar
- Department of Anesthesiology and Critical Care, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania 19104
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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29
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Fuller-Jackson JP, Clarke IJ, Rao A, Henry BA. Exercise counteracts the homeostatic decrease in thermogenesis caused by caloric restriction in sheep. FASEB J 2018; 32:3859-3869. [PMID: 29455575 DOI: 10.1096/fj.201701504r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Caloric restriction causes a homeostatic reduction in thermogenesis. We aimed to determine whether exercise could counteract this. We studied four groups of normal-weight ewes ( n = 5), including control sedentary fed ad libitum, exercise fed ad libitum (30 min/d, 5 d/wk), diet-restricted (70% of ad libitum food intake), and combined diet and exercise. Temperature probes implanted in sternal and retroperitoneal adipose tissue and skeletal muscle measured thermogenesis. After the 4-wk intervention, hypothalami were collected for in situ hybridization, and fat and muscle biopsies were collected for real-time PCR and Western blotting. Combined diet and exercise reduced adiposity ( P < 0.05). Caloric restriction alone reduced overnight temperatures in sternal and retroperitoneal fat ( P < 0.05), which was counteracted by exercise ( P < 0.05). Exercise did not induce expression of cellular markers of browning in adipose tissue. There was no effect of diet or exercise on skeletal muscle thermogenesis. Combined diet and exercise increased the expression of neuropeptide Y and agouti-related protein in the hypothalamic arcuate nucleus ( P < 0.05), consistent with reduced adiposity. Gene expressions of key hypothalamic appetite-regulating peptides were not associated with altered thermogenesis. We demonstrate that exercise counteracts the inhibitory effect of caloric restriction to restore thermogenesis in adipose tissue of sheep.-Fuller-Jackson, J.-P., Clarke, I. J., Rao, A., Henry, B. A. Exercise counteracts the homeostatic decrease in thermogenesis caused by caloric restriction in sheep.
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Affiliation(s)
- John-Paul Fuller-Jackson
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Iain J Clarke
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Alexandra Rao
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Belinda A Henry
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
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30
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Alvarez B, Barrientos T, Gac L, Teske J, Perez-Leighton C. Effects on Hedonic Feeding, Energy Expenditure and Balance of the Non-opioid Peptide DYN-A2-17. Neuroscience 2018; 371:337-345. [DOI: 10.1016/j.neuroscience.2017.11.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 11/11/2017] [Accepted: 11/27/2017] [Indexed: 11/28/2022]
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Abstract
PURPOSE OF REVIEW Spontaneous physical activity (SPA) is a physical activity not motivated by a rewarding goal, such as that associated with food-seeking or wheel-running behavior. SPA is often thought of as only "fidgeting," but that is a mischaracterization, since fidgety behavior can be linked to stereotypies in neurodegenerative disease and other movement disorders. Instead, SPA should be thought of as all physical activity behavior that emanates from an unconscious drive for movement. RECENT FINDINGS An example of this may be restless behavior, which can include fidgeting and gesticulating, frequent sit-to-stand movement, and more time spent standing and moving. All physical activity burns calories, and as such, SPA could be manipulated as a means to burn calories, and defend against weight gain and reduce excess adiposity. In this review, we discuss human and animal literature on the use of SPA in reducing weight gain, the neuromodulators that could be targeted to this end, and future directions in this field.
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Affiliation(s)
- Catherine M Kotz
- Integrative Biology and Physiology, University of Minnesota, 2231 6th St. SE, Minneapolis, MN, 55455, USA.
- GRECC, Minneapolis VA Health Care System, GRECC, One Veterans Drive, Minneapolis, MN, 55417, USA.
| | | | - Jennifer A Teske
- Department of Nutritional Sciences, University of Arizona, 1177 E 4th street, Shantz 332, Tucson, AZ, 85721, USA
| | - Charles J Billington
- Department of Medicine, University of Minnesota, 420 Delaware St SE, Minneapolis, MN, 5545, USA
- Minneapolis VA Health Care System, One Veterans Drive, Minneapolis, MN, 55417, USA
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32
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Zink AN, Bunney PE, Holm AA, Billington CJ, Kotz CM. Neuromodulation of orexin neurons reduces diet-induced adiposity. Int J Obes (Lond) 2017; 42:737-745. [PMID: 29180723 PMCID: PMC5962366 DOI: 10.1038/ijo.2017.276] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/22/2017] [Accepted: 10/04/2017] [Indexed: 01/23/2023]
Abstract
Background/Objectives: Low levels of orexin are associated with obesity and reduced physical activity in humans and animals. Subjects/Methods: Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) selectively activated orexin neurons in mouse lateral hypothalamus (LH) to measure effects on spontaneous physical activity (SPA). DREADD targeting was achieved by stereotaxic injection of AAV vectors into caudal lateral LH of heterozygous orexin-Cre or C57/B6J mice. In one set of studies, excitation of orexin neurons was examined (virus: AAV2-EF1a-DIO-hM3Dq-mCherry), and test sessions began 3-4 h after light cycle onset. In a study examining the inhibition of orexin neurons (virus: AAV2-hSyn-DIO-hM4Di-mCherry), testing began 15 min prior to dark cycle onset. Clozapine n-oxide (CNO; 1 or 5 mg/kg) or saline was injected intraperitoneally and time spent moving in open field chambers was recorded for 2 h. Follow-up studies in separate mouse cohorts quantified SPA in parallel with changes in energy expenditure (EE) and chow intake using indirect calorimetry chambers (SableSystem™). Following acclimation, testing sessions (saline and/or CNO) took place over the course of ~1 week, with injections administered every day. Changes in SPA, EE, chow intake, fecal boli, and body composition (EchoMRI™) were measured. Additional mice cohorts were fed a high-fat diet (HFD) and injected with CNO daily up to 10 days to assess the potential for orexin activation to prevent diet-induced obesity. Results: Activation of orexin resulted in increases in SPA in male and female mice, and was accompanied by increases in energy expenditure without changes in overall chow intake. When orexin activation occurred in the context of high fat diet, weight gain and adiposity were significantly attenuated. SPA was decreased when DREADDs were used to inhibit orexin activity. Conclusion: These results demonstrate that orexin neurons play a critical role in mediating physical activity and suggest a novel therapeutic target for treating obesity.
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Affiliation(s)
- A N Zink
- Medical Devices Center, University of Minnesota, Minneapolis, MN, USA
| | - P E Bunney
- Minnesota Obesity Prevention Training Program, University of Minnesota, Minneapolis, MN, USA.,Geriatric Research Education and Clinical Center, Minneapolis VA Health Care System, Minneapolis, MN, USA
| | - A A Holm
- Food Science and Nutrition, University of Minnesota, Minneapolis, MN, USA
| | - C J Billington
- Food Science and Nutrition, University of Minnesota, Minneapolis, MN, USA.,Department of Medicine, University of Minnesota, Minneapolis, MN, USA.,Minnesota Obesity Center, University of Minnesota, Minneapolis, MN, USA.,Endocrinology section, Minneapolis VA Health Care System, Minneapolis, MN, USA
| | - C M Kotz
- Geriatric Research Education and Clinical Center, Minneapolis VA Health Care System, Minneapolis, MN, USA.,Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
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33
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DePorter DP, Coborn JE, Teske JA. Partial Sleep Deprivation Reduces the Efficacy of Orexin-A to Stimulate Physical Activity and Energy Expenditure. Obesity (Silver Spring) 2017; 25:1716-1722. [PMID: 28815952 DOI: 10.1002/oby.21944] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 06/25/2017] [Accepted: 06/29/2017] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Sufficient sleep is required for weight maintenance. Sleep deprivation due to noise exposure stimulates weight gain by increasing hyperphagia and reducing energy expenditure (EE). Yet the mechanistic basis underlying the weight gain response is unclear. Orexin-A promotes arousal and negative energy balance, and orexin terminals project to the ventrolateral preoptic area (VLPO), which is involved in sleep-to-wake transitions. To determine whether sleep deprivation reduces orexin function in VLPO and to test the hypothesis that sleep deprivation would attenuate the orexin-A-stimulated increase in arousal, physical activity (PA), and EE. METHODS Electroencephalogram, electromyogram, distance traveled, and EE were determined in male Sprague-Dawley rats following orexin-A injections into VLPO both before and after acute (12-h) and chronic (8 h/d, 9 d) sleep deprivation by noise exposure. RESULTS Orexin-A in the VLPO significantly increased arousal, PA, total EE, and PA-related EE and reduced sleep and respiratory quotient before sleep deprivation. In contrast to after acute sleep deprivation in which orexin-A failed to stimulate EE during PA only, orexin-A failed to significantly increase arousal, PA, fat oxidation, total EE, and PA-related EE after chronic sleep deprivation. CONCLUSIONS Sleep deprivation may reduce sensitivity to endogenous stimuli that enhance EE due to PA and thus stimulate weight gain.
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Affiliation(s)
- Danielle P DePorter
- Department of Nutritional Sciences, University of Arizona, Tucson, Arizona, USA
| | - Jamie E Coborn
- Department of Nutritional Sciences, University of Arizona, Tucson, Arizona, USA
| | - Jennifer A Teske
- Department of Nutritional Sciences, University of Arizona, Tucson, Arizona, USA
- Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
- Department of Food Science & Nutrition, University of Minnesota, Saint Paul, Minnesota, USA
- Minnesota Obesity Center, University of Minnesota, Saint Paul, Minnesota, USA
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34
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Baimel C, Borgland SL. Hypocretin/Orexin and Plastic Adaptations Associated with Drug Abuse. Curr Top Behav Neurosci 2017; 33:283-304. [PMID: 28303403 DOI: 10.1007/7854_2016_44] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Dopamine neurons in the ventral tegmental area (VTA) are a critical part of the neural circuits that underlie reward learning and motivation. Dopamine neurons send dense projections throughout the brain and recent observations suggest that both the intrinsic properties and the functional output of dopamine neurons are dependent on projection target and are subject to neuromodulatory influences. Lateral hypothalamic hypocretin (also termed orexin) neurons project to the VTA and contain both hypocretin and dynorphin peptides in the same dense core vesicles suggesting they may be co-released. Hypocretin peptides act at excitatory Gαq protein-coupled receptors and dynorphin acts at inhibitory Gαi/o protein-coupled receptors, which are both expressed on subpopulations of dopamine neurons. This review describes a role for neuromodulation of dopamine neurons and the influence on motivated behaviour in response to natural and drug rewards.
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Affiliation(s)
- Corey Baimel
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, Canada, V6T 1Z3
- Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, Canada, T2N 4N1
| | - Stephanie L Borgland
- Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, Canada, T2N 4N1.
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35
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Goforth PB, Myers MG. Roles for Orexin/Hypocretin in the Control of Energy Balance and Metabolism. Curr Top Behav Neurosci 2017; 33:137-156. [PMID: 27909992 DOI: 10.1007/7854_2016_51] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The neuropeptide hypocretin is also commonly referred to as orexin, since its orexigenic action was recognized early. Orexin/hypocretin (OX) neurons project widely throughout the brain and the physiologic and behavioral functions of OX are much more complex than initially conceived based upon the stimulation of feeding. OX most notably controls functions relevant to attention, alertness, and motivation. OX also plays multiple crucial roles in the control of food intake, metabolism, and overall energy balance in mammals. OX signaling not only promotes food-seeking behavior upon short-term fasting to increase food intake and defend body weight, but, conversely, OX signaling also supports energy expenditure to protect against obesity. Furthermore, OX modulates the autonomic nervous system to control glucose metabolism, including during the response to hypoglycemia. Consistently, a variety of nutritional cues (including the hormones leptin and ghrelin) and metabolites (e.g., glucose, amino acids) control OX neurons. In this chapter, we review the control of OX neurons by nutritional/metabolic cues, along with our current understanding of the mechanisms by which OX and OX neurons contribute to the control of energy balance and metabolism.
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Affiliation(s)
- Paulette B Goforth
- Department of Pharmacology, University of Michigan, 1000 Wall St, 5131 Brehm Tower, Ann Arbor, MI, 48105, USA
| | - Martin G Myers
- Departments of Internal Medicine, and Molecular and Integrative Physiology, University of Michigan, 1000 Wall St, 6317 Brehm Tower, Ann Arbor, MI, 48105, USA.
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36
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Bunney PE, Zink AN, Holm AA, Billington CJ, Kotz CM. Orexin activation counteracts decreases in nonexercise activity thermogenesis (NEAT) caused by high-fat diet. Physiol Behav 2017; 176:139-148. [PMID: 28363838 PMCID: PMC5510739 DOI: 10.1016/j.physbeh.2017.03.040] [Citation(s) in RCA: 779] [Impact Index Per Article: 111.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 03/27/2017] [Accepted: 03/27/2017] [Indexed: 02/06/2023]
Abstract
Overweight and obesity result from an imbalance between caloric intake and energy expenditure, including expenditure from spontaneous physical activity (SPA). Changes in SPA and resulting changes in non-exercise activity thermogenesis (NEAT) likely interact with diet to influence risk for obesity. However, previous research on the relationship between diet, physical activity, and energy expenditure has been mixed. The neuropeptide orexin is a driver of SPA, and orexin neuron activity can be manipulated using DREADDs (Designer Receptors Exclusively Activated by Designer Drugs). We hypothesized that HFD decreases SPA and NEAT, and that DREADD-mediated activation of orexin neuron signaling would abolish this decrease and produce an increase in NEAT instead. To test these ideas, we characterized behaviors to determine the extent to which access to a high-fat diet (HFD) influences the proportion and probability of engaging in food intake and activity. We then measured NEAT following access to HFD and following a DREADD intervention targeting orexin neurons. Two cohorts of orexin-cre male mice were injected with an excitatory DREADD virus into the caudal hypothalamus, where orexin neurons are concentrated. Mice were then housed in continuous metabolic phenotyping cages (Sable Promethion). Food intake, indirect calorimetry, and SPA were automatically measured every second. For cohort 1 (n=8), animals were given access to chow, then switched to HFD. For cohort 2 (n=4/group), half of the animals were given access to HFD, the other access to chow. Then, among animals on HFD, orexin neurons were activated following injections of clozapine n-oxide (CNO). Mice on HFD spent significantly less time eating (p<0.01) and more time inactive compared to mice on chow (p<0.01). Following a meal, mice on HFD were significantly more likely to engage in periods of inactivity compared to those on chow (p<0.05). NEAT was decreased in animals on HFD, and was increased to the NEAT level of control animals following activation of orexin neurons with DREADDs. Food intake (kilocalories) was not significantly different between mice on chow and HFD, yet mice on chow expended more energy per unit of SPA, relative to that in mice consuming HFD. These results suggest that HFD consumption reduces SPA and NEAT, and increases inactivity following a meal. Together, the data suggest a change in the efficiency of energy expenditure based upon diet, such that SPA during HFD burns fewer calories compared to SPA on a standard chow diet.
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Affiliation(s)
- P E Bunney
- Minnesota Obesity Prevention Training Program, University of Minnesota, United States; Geriatric Research and Clinical Center, Minneapolis VA Health Care System, United States.
| | - A N Zink
- Medical Devices Center, University of Minnesota, United States
| | - A A Holm
- Food Science and Nutrition, University of Minnesota, United States
| | - C J Billington
- Department of Medicine, University of Minnesota, United States; Minnesota Obesity Center, University of Minnesota, United States; Department of Medicine, Minneapolis VA Health Care System, United States
| | - C M Kotz
- Geriatric Research and Clinical Center, Minneapolis VA Health Care System, United States; Minnesota Obesity Center, University of Minnesota, United States; Department of Integrative Biology and Physiology, University of Minnesota, United States
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37
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Coborn JE, DePorter DP, Mavanji V, Sinton CM, Kotz CM, Billington CJ, Teske JA. Role of orexin-A in the ventrolateral preoptic area on components of total energy expenditure. Int J Obes (Lond) 2017; 41:1256-1262. [PMID: 28392556 DOI: 10.1038/ijo.2017.92] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 03/20/2017] [Accepted: 03/26/2017] [Indexed: 12/23/2022]
Abstract
BACKGROUND Identifying whether components of total energy expenditure (EE) are affected by orexin receptor (OXR1 and OXR2) stimulation or antagonism with dual orexin receptor antagonists (DORAs) has relevance for obesity treatment. Orexin receptor stimulation reduces weight gain by increasing total EE and EE during spontaneous physical activity (SPA). OBJECTIVE The purpose of this study was to determine if a DORA (TCS-1102) in the ventrolateral preoptic area (VLPO) reduced orexin-A-induced arousal, SPA, total EE and EE during sleep, rest, wake and SPA and whether the DORA alone reduced total EE and its components. We hypothesized that: (1) a DORA would reduce orexin-A induced increases in arousal, SPA, components of total EE, reductions in sleep and the EE during sleep and (2) the DORA alone would reduce baseline (non-stimulated) SPA and total EE. SUBJECTS/METHODS Sleep, wakefulness, SPA and EE were determined after microinjection of the DORA (TCS-1102) and orexin-A in the VLPO of male Sprague-Dawley rats with a unilateral cannula targeted towards the VLPO. Individual components of total EE were determined based on time-stamped data. RESULTS The DORA reduced orexin-A-induced increases in arousal, SPA, total EE and EE during SPA, wake, rest and sleep 1 h post injection (P<0.05). Orexin-A significantly reduced sleep and significantly increased EE during sleep 1 h post injection (P<0.05). Furthermore, the DORA alone significantly reduced total EE, EE during sleep (NREM and REM) and resting EE 2 h post injection (P<0.05). CONCLUSIONS These data suggest that orexin-A reduces weight gain by stimulating total EE through increases in EE during SPA, rest and sleep. Residual effects of the DORA alone include decreases in total EE and EE during sleep and rest, which may promote weight gain.
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Affiliation(s)
- J E Coborn
- Department of Nutritional Sciences, University of Arizona, Tucson, AZ, USA
| | - D P DePorter
- Department of Nutritional Sciences, University of Arizona, Tucson, AZ, USA
| | - V Mavanji
- Minneapolis VA Health Care System, Minneapolis, MN, USA
| | - C M Sinton
- Arizona Respiratory Center, University of Arizona, Tucson, AZ, USA
| | - C M Kotz
- Minneapolis VA Health Care System, Minneapolis, MN, USA.,Geriatric Research Education and Clinical Center, Minneapolis, MN, USA.,Minnesota Obesity Center, Saint Paul, MN, USA.,Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN, USA
| | - C J Billington
- Minneapolis VA Health Care System, Minneapolis, MN, USA.,Minnesota Obesity Center, Saint Paul, MN, USA.,Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN, USA.,Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - J A Teske
- Department of Nutritional Sciences, University of Arizona, Tucson, AZ, USA.,Minneapolis VA Health Care System, Minneapolis, MN, USA.,Minnesota Obesity Center, Saint Paul, MN, USA.,Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN, USA
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Emam AH, Hajesfandiari N, Shahidi S, Komaki A, Ganji M, Sarihi A. Modulation of nociception by medial pre-optic area orexin a receptors and its relation with morphine in male rats. Brain Res Bull 2016; 127:141-147. [PMID: 27641968 DOI: 10.1016/j.brainresbull.2016.09.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 09/13/2016] [Accepted: 09/14/2016] [Indexed: 12/29/2022]
Abstract
INTRODUCTION Recent studies have shown that medial pre-optic area (MPOA) of hypothalamus are involved in nociception. Orexin A (hypocretin 1) has been found to have numerous applications including pain modulation. However, the role of orexin A receptors in the MPOA on the nociception has not been yet studied. Therefore, the aim of the present study is to investigate the effect of orexin A microinjection on MPOA on the nociception transmission and morphine induced analgesia in adult male rats. METHODS Using stereotaxic surgery, a cannula was implanted at a site 1mm above the MPOA in the anesthetized rats. After the recovery period, tail-flick (TF) latency was measured as 0, 15, 30, 45 and 60min following the onset of two experimental protocols. Two experiments were carried out. Experiment 1: The male rats received intra-MPOA of 25, 100, 1000, 10000pmol/0.5μl orexin A or 0.5μl of aCSF (control, just 5min before the TF assay. Experiment 2: The aim of this experiment was to examine the effect of orexin microinjection into MPOA on morphine analgesia (3mg/kg,s.c). Morphine was administered 30min before orexin A intra-MPOA microinjection (four doses similar to experiment 1) or aCSF, then TF latency was measured. RESULTS The results indicated that microinjection of orexin A into the MPOA showed anti-nociceptive effect in a time-dependent manner. Dose response curve results also revealed that the maximum effective dose of orexin A injection into MPOA for pain inhibition is 1000pmol/0.5μl. Co-administration of systemic morphine and orexin into the MPOA has additive analgesia with different time course compared morphine or orexin alone. CONCLUSION It can be concluded that MPOA OrexinA receptors play an important role in the modulation of pain in normal and morphine treated male rats.
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Affiliation(s)
- Amir Hossein Emam
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Naeimeh Hajesfandiari
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Siamak Shahidi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Alireza Komaki
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Maziar Ganji
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Abdolrahman Sarihi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
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Terrill SJ, Hyde KM, Kay KE, Greene HE, Maske CB, Knierim AE, Davis JF, Williams DL. Ventral tegmental area orexin 1 receptors promote palatable food intake and oppose postingestive negative feedback. Am J Physiol Regul Integr Comp Physiol 2016; 311:R592-9. [PMID: 27385732 DOI: 10.1152/ajpregu.00097.2016] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 06/26/2016] [Indexed: 01/21/2023]
Abstract
Hypothalamic orexin neurons project to numerous brain areas, including the ventral tegmental area (VTA), which is involved in motivation and food-seeking behavior. Here we address how exogenously administered orexin-A and endogenous orexin 1 receptor (OX1R) activation in the VTA affects feeding behavior. We hypothesized that orexin-A and OX1R antagonist SB334867 delivered to the VTA, at doses that were subthreshold for effect when injected into the ventricle, would affect intake of palatable foods in multiple test situations. We first used a hedonic feeding model in which satiated rats selectively consume a high-fat diet (HFD). Intra-VTA orexin-A stimulated additional consumption of chow and increased HFD intake in this model. In ad libitum-fed rats given daily 30-min test sessions, intra-VTA orexin-A also increased intake of HFD and 0.1 M sucrose. Further analysis of licking patterns revealed that that VTA orexin-A increased meal size and licking burst size only toward the end of the meal. Consistent with this finding, a subthreshold dose of VTA orexin-A prevented intake suppression induced by gastrointestinal nutrient infusion. Surprisingly, intra-VTA orexin-A had no effect on operant responding for sucrose pellets on a progressive ratio schedule of reinforcement. A role for endogenous VTA OX1R stimulation is supported by our finding that bilateral VTA injection of the selective OX1R antagonist SB334867 suppressed 0.1 M sucrose intake. Together, our data suggest that OX1R activity in the VTA facilitates food intake, potentially by counteracting postingestive negative feedback that would normally suppress feeding later in a meal.
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Affiliation(s)
- Sarah J Terrill
- Department of Psychology & Program in Neuroscience, Florida State University, Tallahassee, Florida; and
| | - Kellie M Hyde
- Department of Psychology & Program in Neuroscience, Florida State University, Tallahassee, Florida; and
| | - Kristen E Kay
- Department of Psychology & Program in Neuroscience, Florida State University, Tallahassee, Florida; and
| | - Hayden E Greene
- Department of Psychology & Program in Neuroscience, Florida State University, Tallahassee, Florida; and
| | - Calyn B Maske
- Department of Psychology & Program in Neuroscience, Florida State University, Tallahassee, Florida; and
| | - Amanda E Knierim
- Department of Psychology & Program in Neuroscience, Florida State University, Tallahassee, Florida; and
| | - Jon F Davis
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Diana L Williams
- Department of Psychology & Program in Neuroscience, Florida State University, Tallahassee, Florida; and
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Teske JA, Perez-Leighton CE, Noble EE, Wang C, Billington CJ, Kotz CM. Effect of Housing Types on Growth, Feeding, Physical Activity, and Anxiety-Like Behavior in Male Sprague-Dawley Rats. Front Nutr 2016; 3:4. [PMID: 26870735 PMCID: PMC4740365 DOI: 10.3389/fnut.2016.00004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Accepted: 01/15/2016] [Indexed: 01/15/2023] Open
Abstract
Background Animal welfare and accurate data collection are equally important in rodent research. Housing influences study outcomes and can challenge studies that monitor feeding, so housing choice needs to be evidence-based. The goal of these studies was to (1) compare established measures of well-being between rodents housed in wire grid-bottom floors with a resting platform compared to solid-bottom floors with bedding and (2) determine whether presence of a chewable device (Nylabone) affects orexin-A-induced hyperphagia. Methods Rodents were crossed over to the alternate housing twice after 2-week periods. Time required to complete food intake measurements was recorded as an indicator of feasibility. Food intake stimulated by orexin-A was compared with and without the Nylabone. Blood corticosterone and hypothalamic BDNF were assessed. Results Housing had no effect on growth, energy expenditure, corticosterone, hypothalamic BDNF, behavior, and anxiety measures. Food intake was disrupted after housing cross-over. Time required to complete food intake measurements was significantly higher for solid-bottom bedded cages. The Nylabone had no effect on orexin-A-stimulated feeding. Conclusion Well-being is not significantly different between rodents housed on grid-bottom floors and those in solid-bottom-bedded cages based on overall growth and feeding but alternating between housing confounds measures of feeding.
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Affiliation(s)
- Jennifer A Teske
- Department of Nutritional Sciences, University of Arizona, Tucson, AZ, USA; Minneapolis VA Health Care System, Minneapolis, MN, USA; Minnesota Obesity Center, University of Minnesota, Saint Paul, MN, USA; Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN, USA
| | - Claudio Esteban Perez-Leighton
- Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN, USA; Center for Integrative Medicine and Innovative Science, Universidad Andres Bello, Santiago, Chile
| | - Emily E Noble
- Department of Integrative Biology and Physiology, University of California Los Angeles , Los Angeles, CA , USA
| | - Chuanfeng Wang
- Minneapolis VA Health Care System, Minneapolis, MN, USA; Minnesota Obesity Center, University of Minnesota, Saint Paul, MN, USA; Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN, USA
| | - Charles J Billington
- Minneapolis VA Health Care System, Minneapolis, MN, USA; Minnesota Obesity Center, University of Minnesota, Saint Paul, MN, USA; Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN, USA; Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Catherine M Kotz
- Minneapolis VA Health Care System, Minneapolis, MN, USA; Minnesota Obesity Center, University of Minnesota, Saint Paul, MN, USA; Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN, USA; Geriatric Research Education and Clinical Center, Minneapolis VA Health Care System, Minneapolis, MN, USA
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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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Sarihi A, Emam AH, Panah MH, Komaki A, Seif S, Vafaeirad M, Alaii E. Effects of activation and blockade of orexin A receptors in the medial preoptic area on food intake in male rats. Neurosci Lett 2015; 604:157-60. [DOI: 10.1016/j.neulet.2015.07.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Revised: 06/16/2015] [Accepted: 07/31/2015] [Indexed: 01/20/2023]
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43
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Mavanji V, Perez-Leighton CE, Kotz CM, Billington CJ, Parthasarathy S, Sinton CM, Teske JA. Promotion of Wakefulness and Energy Expenditure by Orexin-A in the Ventrolateral Preoptic Area. Sleep 2015; 38:1361-70. [PMID: 25845696 DOI: 10.5665/sleep.4970] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 03/07/2015] [Indexed: 12/25/2022] Open
Abstract
STUDY OBJECTIVES The ventrolateral preoptic area (VLPO) and the orexin/hypocretin neuronal system are key regulators of sleep onset, transitions between vigilance states, and energy homeostasis. Reciprocal projections exist between the VLPO and orexin/hypocretin neurons. Although the importance of the VLPO to sleep regulation is clear, it is unknown whether VLPO neurons are involved in energy balance. The purpose of these studies was to determine if the VLPO is a site of action for orexin-A, and which orexin receptor subtype(s) would mediate these effects of orexin-A. We hypothesized that orexin-A in the VLPO modulates behaviors (sleep and wakefulness, feeding, spontaneous physical activity [SPA]) to increase energy expenditure. DESIGN AND MEASUREMENTS Sleep, wakefulness, SPA, feeding, and energy expenditure were determined after orexin-A microinjection in the VLPO of male Sprague-Dawley rats with unilateral cannulae targeting the VLPO. We also tested whether pretreatment with a dual orexin receptor antagonist (DORA, TCS-1102) or an OX2R antagonist (JNJ-10397049) blocked the effects of orexin-A on the sleep/wake cycle or SPA, respectively. RESULTS Orexin-A injected into the VLPO significantly increased wakefulness, SPA, and energy expenditure (SPA-induced and total) and reduced NREM sleep and REM sleep with no effect on food intake. Pretreatment with DORA blocked the increase in wakefulness and the reduction in NREM sleep elicited by orexin-A, and the OX2R antagonist reduced SPA stimulated by orexin-A. CONCLUSIONS These data show the ventrolateral preoptic area is a site of action for orexin-A, which may promote negative energy balance by modulating sleep/wakefulness and stimulating spontaneous physical activity and energy expenditure.
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Affiliation(s)
| | - Claudio E Perez-Leighton
- Center for Integrative Medicine and Innovative Science, Universidad Andres Bello, Santiago, Chile.,Escuela de Nutricion, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Catherine M Kotz
- Minneapolis VA Health Care System, Minneapolis, MN.,Geriatric Research Education and Clinical Center, Minneapolis, MN.,Minnesota Obesity Center, University of Minnesota, Saint Paul, MN.,Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN
| | - Charles J Billington
- Minneapolis VA Health Care System, Minneapolis, MN.,Minnesota Obesity Center, University of Minnesota, Saint Paul, MN.,Department of Medicine, University of Minnesota, Saint Paul, MN.,Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN
| | - Sairam Parthasarathy
- Arizona Respiratory Center University of Arizona, Tucson, AZ.,Department of Medicine University of Arizona, Tucson, AZ
| | - Christopher M Sinton
- Arizona Respiratory Center University of Arizona, Tucson, AZ.,Department of Medicine University of Arizona, Tucson, AZ
| | - Jennifer A Teske
- Department of Nutritional Sciences, University of Arizona, Tucson, AZ.,Minneapolis VA Health Care System, Minneapolis, MN.,Minnesota Obesity Center, University of Minnesota, Saint Paul, MN.,Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN
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García AP, Aitta-aho T, Schaaf L, Heeley N, Heuschmid L, Bai Y, Barrantes FJ, Apergis-Schoute J. Nicotinic α4 Receptor-Mediated Cholinergic Influences on Food Intake and Activity Patterns in Hypothalamic Circuits. PLoS One 2015; 10:e0133327. [PMID: 26247203 PMCID: PMC4527587 DOI: 10.1371/journal.pone.0133327] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 06/24/2015] [Indexed: 12/22/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) play an important role in regulating appetite and have been shown to do so by influencing neural activity in the hypothalamus. To shed light on the hypothalamic circuits governing acetylcholine's (ACh) regulation of appetite this study investigated the influence of hypothalamic nAChRs expressing the α4 subunit. We found that antagonizing the α4β2 nAChR locally in the lateral hypothalamus with di-hydro-ß-erythroidine (DHβE), an α4 nAChR antagonist with moderate affinity, caused an increase in food intake following free access to food after a 12 hour fast, compared to saline-infused animals. Immunocytochemical analysis revealed that orexin/hypocretin (HO), oxytocin, and tyrosine hydroxylase (TH)-containing neurons in the A13 and A12 of the hypothalamus expressed the nAChR α4 subunit in varying amounts (34%, 42%, 50%, and 51%, respectively) whereas melanin concentrating hormone (MCH) neurons did not, suggesting that DHβE-mediated increases in food intake may be due to a direct activation of specific hypothalamic circuits. Systemic DHβE (2 mg/kg) administration similarly increased food intake following a 12 hour fast. In these animals a subpopulation of orexin/hypocretin neurons showed elevated activity compared to control animals and MCH neuronal activity was overall lower as measured by expression of the immediate early gene marker for neuronal activity cFos. However, oxytocin neurons in the paraventricular hypothalamus and TH-containing neurons in the A13 and A12 did not show differential activity patterns. These results indicate that various neurochemically distinct hypothalamic populations are under the influence of α4β2 nAChRs and that cholinergic inputs to the lateral hypothalamus can affect satiety signals through activation of local α4β2 nAChR-mediated transmission.
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Affiliation(s)
- Ana P. García
- Department of Pharmacology, University of Cambridge; Cambridge, United Kingdom
- Laboratory of Molecular Neurobiology, Biomedical Research Institute (BIOMED) UCA–CONICET, Faculty of Medical Sciences, Catholic University of Argentina, Buenos Aires, Argentina
| | - Teemu Aitta-aho
- Department of Pharmacology, University of Cambridge; Cambridge, United Kingdom
| | - Laura Schaaf
- Department of Pharmacology, University of Cambridge; Cambridge, United Kingdom
| | - Nicholas Heeley
- Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Lena Heuschmid
- Department of Pharmacology, University of Cambridge; Cambridge, United Kingdom
| | - Yunjing Bai
- Department of Pharmacology, University of Cambridge; Cambridge, United Kingdom
- Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
| | - Francisco J. Barrantes
- Laboratory of Molecular Neurobiology, Biomedical Research Institute (BIOMED) UCA–CONICET, Faculty of Medical Sciences, Catholic University of Argentina, Buenos Aires, Argentina
| | - John Apergis-Schoute
- Department of Pharmacology, University of Cambridge; Cambridge, United Kingdom
- Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
- * E-mail:
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Abstract
Sitting too much kills. Epidemiological, physiological and molecular data suggest that sedentary lifestyle can explain, in part, how modernity is associated with obesity, more than 30 chronic diseases and conditions and high healthcare costs. Excessive sitting--sitting disease--is not innate to the human condition. People were designed to be bipedal and, before the industrial revolution, people moved substantially more throughout the day than they do presently. It is encouraging that solutions exist to reverse sitting disease. Work environments, schools, communities and cities can be re-imagined and re-invented as walking spaces, and people thereby offered more active, happier, healthier and more productive lives.
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Affiliation(s)
- James A Levine
- Mayo Clinic, 13400 East Shea Blvd, Scottsdale, AZ, 85259, USA,
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Nixon JP, Mavanji V, Butterick TA, Billington CJ, Kotz CM, Teske JA. Sleep disorders, obesity, and aging: the role of orexin. Ageing Res Rev 2015; 20:63-73. [PMID: 25462194 DOI: 10.1016/j.arr.2014.11.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 09/19/2014] [Accepted: 11/14/2014] [Indexed: 02/03/2023]
Abstract
The hypothalamic neuropeptides orexin A and B (hypocretin 1 and 2) are important homeostatic mediators of central control of energy metabolism and maintenance of sleep/wake states. Dysregulation or loss of orexin signaling has been linked to narcolepsy, obesity, and age-related disorders. In this review, we present an overview of our current understanding of orexin function, focusing on sleep disorders, energy balance, and aging, in both rodents and humans. We first discuss animal models used in studies of obesity and sleep, including loss of function using transgenic or viral-mediated approaches, gain of function models using exogenous delivery of orexin receptor agonist, and naturally-occurring models in which orexin responsiveness varies by individual. We next explore rodent models of orexin in aging, presenting evidence that orexin loss contributes to age-related changes in sleep and energy balance. In the next section, we focus on clinical importance of orexin in human obesity, sleep, and aging. We include discussion of orexin loss in narcolepsy and potential importance of orexin in insomnia, correlations between animal and human studies of age-related decline, and evidence for orexin involvement in age-related changes in cognitive performance. Finally, we present a summary of recent studies of orexin in neurodegenerative disease. We conclude that orexin acts as an integrative homeostatic signal influencing numerous brain regions, and that this pivotal role results in potential dysregulation of multiple physiological processes when orexin signaling is disrupted or lost.
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Baimel C, Bartlett SE, Chiou LC, Lawrence AJ, Muschamp JW, Patkar O, Tung LW, Borgland SL. Orexin/hypocretin role in reward: implications for opioid and other addictions. Br J Pharmacol 2015; 172:334-48. [PMID: 24641197 PMCID: PMC4292951 DOI: 10.1111/bph.12639] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 01/24/2014] [Accepted: 01/31/2014] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Addiction is a devastating disorder that affects 15.3 million people worldwide. While prevalent, few effective treatments exist. Orexin receptors have been proposed as a potential target for anti-craving medications. Orexins, also known as hypocretins, are neuropeptides produced in neurons of the lateral and dorsomedial hypothalamus and perifornical area, which project widely throughout the brain. The absence of orexins in rodents and humans leads to narcolepsy. However, orexins also have an established role in reward seeking. This review will discuss some of the original studies describing the roles of the orexins in reward seeking as well as specific works that were presented at the 2013 International Narcotics Research Conference. Orexin signalling can promote drug-induced plasticity of glutamatergic synapses onto dopamine neurons of the ventral tegmental area (VTA), a brain region implicated in motivated behaviour. Additional evidence suggests that orexin signalling can also promote drug seeking by initiating an endocannabinoid-mediated synaptic depression of GABAergic inputs to the VTA, and thereby disinhibiting dopaminergic neurons. Orexin neurons co-express the inhibitory opioid peptide dynorphin. It has been proposed that orexin in the VTA may not mediate reward per se, but rather occludes the 'anti-reward' effects of dynorphin. Finally, orexin signalling in the prefrontal cortex and the central amygdala is implicated in reinstatement of reward seeking. This review will highlight recent work describing the role of orexin signalling in cellular processes underlying addiction-related behaviours and propose novel hypotheses for the mechanisms by which orexin signalling may impart drug seeking. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Affiliation(s)
- Corey Baimel
- Department of Physiology and Pharmacology, The University of CalgaryCalgary, AB, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, The University of British ColumbiaVancouver, BC, Canada
| | - Selena E Bartlett
- Translational Research Institute, Institute for Health and Biomedical Sciences, Faculty of Health Queensland University of TechnologyBrisbane, QLD, Australia
| | - Lih-Chu Chiou
- Graduate Institute of Pharmacology, College of Medicine, National Taiwan UniversityTaipei, Taiwan
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan UniversityTaipei, Taiwan
| | - Andrew J Lawrence
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, VIC, Australia
| | - John W Muschamp
- Center for Substance Abuse Research, Department of Pharmacology, School of Medicine, Temple UniversityPhiladelphia, PA, USA
| | - Omkar Patkar
- Translational Research Institute, Institute for Health and Biomedical Sciences, Faculty of Health Queensland University of TechnologyBrisbane, QLD, Australia
| | - Li-Wei Tung
- Graduate Institute of Pharmacology, College of Medicine, National Taiwan UniversityTaipei, Taiwan
| | - Stephanie L Borgland
- Department of Physiology and Pharmacology, The University of CalgaryCalgary, AB, Canada
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Zink AN, Perez-Leighton CE, Kotz CM. The orexin neuropeptide system: physical activity and hypothalamic function throughout the aging process. Front Syst Neurosci 2014; 8:211. [PMID: 25408639 PMCID: PMC4219460 DOI: 10.3389/fnsys.2014.00211] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 10/07/2014] [Indexed: 12/18/2022] Open
Abstract
There is a rising medical need for novel therapeutic targets of physical activity. Physical activity spans from spontaneous, low intensity movements to voluntary, high-intensity exercise. Regulation of spontaneous and voluntary movement is distributed over many brain areas and neural substrates, but the specific cellular and molecular mechanisms responsible for mediating overall activity levels are not well understood. The hypothalamus plays a central role in the control of physical activity, which is executed through coordination of multiple signaling systems, including the orexin neuropeptides. Orexin producing neurons integrate physiological and metabolic information to coordinate multiple behavioral states and modulate physical activity in response to the environment. This review is organized around three questions: (1) How do orexin peptides modulate physical activity? (2) What are the effects of aging and lifestyle choices on physical activity? (3) What are the effects of aging on hypothalamic function and the orexin peptides? Discussion of these questions will provide a summary of the current state of knowledge regarding hypothalamic orexin regulation of physical activity during aging and provide a platform on which to develop improved clinical outcomes in age-associated obesity and metabolic syndromes.
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Affiliation(s)
- Anastasia N Zink
- Graduate Program in Neuroscience, School of Medicine, University of Minnesota Minneapolis, MN, USA
| | | | - Catherine M Kotz
- Graduate Program in Neuroscience, School of Medicine, University of Minnesota Minneapolis, MN, USA ; GRECC (11G), Minneapolis VA Healthcare System Minneapolis, MN, USA ; Department of Food Science and Nutrition, University of Minnesota Saint Paul, MN, USA
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Jalewa J, Wong-Lin K, McGinnity TM, Prasad G, Hölscher C. Increased number of orexin/hypocretin neurons with high and prolonged external stress-induced depression. Behav Brain Res 2014; 272:196-204. [DOI: 10.1016/j.bbr.2014.05.030] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 05/13/2014] [Accepted: 05/16/2014] [Indexed: 01/14/2023]
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50
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Li J, Hu Z, de Lecea L. The hypocretins/orexins: integrators of multiple physiological functions. Br J Pharmacol 2014; 171:332-50. [PMID: 24102345 DOI: 10.1111/bph.12415] [Citation(s) in RCA: 181] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Revised: 07/16/2013] [Accepted: 08/02/2013] [Indexed: 12/28/2022] Open
Abstract
The hypocretins (Hcrts), also known as orexins, are two peptides derived from a single precursor produced in the posterior lateral hypothalamus. Over the past decade, the orexin system has been associated with numerous physiological functions, including sleep/arousal, energy homeostasis, endocrine, visceral functions and pathological states, such as narcolepsy and drug abuse. Here, we review the discovery of Hcrt/orexins and their receptors and propose a hypothesis as to how the orexin system orchestrates these multifaceted physiological functions.
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Affiliation(s)
- Jingcheng Li
- Department of Physiology, Third Military Medical University, Chongqing, China
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