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Aldridge GM, Zarin TA, Brandner AJ, George O, Gilpin NW, Repunte-Canonigo V, Sanna PP, Koob GF, Vendruscolo LF, Schmeichel BE. Effects of single and dual hypocretin-receptor blockade or knockdown of hypocretin projections to the central amygdala on alcohol drinking in dependent male rats. ADDICTION NEUROSCIENCE 2022; 3:100028. [PMID: 35965958 PMCID: PMC9365098 DOI: 10.1016/j.addicn.2022.100028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Hypocretin/Orexin (HCRT) is a neuropeptide that is associated with both stress and reward systems in humans and rodents. The different contributions of signaling at hypocretin-receptor 1 (HCRT-R1) and hypocretin-receptor 2 (HCRT-R2) to compulsive alcohol drinking are not yet fully understood. Thus, the current studies used pharmacological and viral-mediated targeting of HCRT to determine participation in compulsive alcohol drinking and measured HCRT-receptor mRNA expression in the extended amygdala of both alcohol-dependent and non-dependent male rats. Rats were made dependent through chronic intermittent exposure to alcohol vapor and were tested for the acute effect of HCRT-R1-selective (SB-408124; SB-R1), HCRT-R2-selective (NBI-80713; NB-R2), or dual HCRT-R1/2 (NBI-87571; NB-R1/2) antagonism on alcohol intake. NB-R2 and NB-R1/2 antagonists each dose-dependently decreased overall alcohol drinking in alcohol-dependent rats, whereas, SB-R1 decreased alcohol drinking in both alcohol-dependent and non-dependent rats at the highest dose (30 mg/kg). SB-R1, NB-R2, and NB-R1/2 treatment did not significantly affect water drinking in either alcohol-dependent or non-dependent rats. Additional PCR analyses revealed a significant decrease in Hcrtr1 mRNA expression within the central amygdala (CeA) of dependent rats under acute withdrawal conditions compared to nondependent rats. Lastly, a shRNA-encoding adeno-associated viral vector with retrograde function was used to knockdown HCRT in CeA-projecting neurons from the lateral hypothalamus (LH). LH-CeA HCRT knockdown significantly attenuated alcohol self-administration in alcohol-dependent rats. These observations suggest that HCRT signaling in the CeA is necessary for alcohol-seeking behavior during dependence. Together, these data highlight a role for both HCRT-R1 and -R2 in dependent alcohol-seeking behavior.
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Affiliation(s)
- Gabriel M. Aldridge
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
| | - Tyler A. Zarin
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
| | - Adam J. Brandner
- Integrative Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Olivier George
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
- Department of Psychiatry, School of Medicine, University of California, San Diego, San Diego, CA, USA
| | - Nicholas W. Gilpin
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, USA
| | - Vez Repunte-Canonigo
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
- Department of Immunology and Microbiology, Scripps Research, La Jolla, CA 92037, United States
| | - Pietro P. Sanna
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
- Department of Immunology and Microbiology, Scripps Research, La Jolla, CA 92037, United States
| | - George F. Koob
- Integrative Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Leandro F. Vendruscolo
- Integrative Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Brooke E. Schmeichel
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
- Integrative Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
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Celli R, van Luijtelaar G. The Orexin System: A Potential Player in the Pathophysiology of Absence Epilepsy. Curr Neuropharmacol 2022; 20:1254-1260. [PMID: 34911428 PMCID: PMC9881075 DOI: 10.2174/1570159x19666211215122833] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/28/2021] [Accepted: 11/09/2021] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Absence epilepsy is characterized by the presence of spike-and-wave discharges (SWDs) at the EEG generated within the cortico-thalamo-cortical circuit. The molecular mechanisms involved in the pathophysiology of absence epilepsy are only partially known. WAG/Rij rats older than 2-3 months develop spontaneous SWDs, and they are sensitive to anti- absence medications. Hence, WAG/Rij rats are extensively used as a model for absence epilepsy with predictive validity. OBJECTIVE The aim of the study was to examine the possibility that the orexin system, which supports the wake status in experimental animals and humans, plays a role in the pathophysiology of absence seizures. METHODS The perspective grounds its method from recent literature along with measurements of orexin receptor type-1 (OX1) protein levels in the thalamus and somatosensory cortex of WAG/Rij rats and non-epileptic Wistar control rats at two ages (25 days and 6-7 months). OX1 protein levels were measured by immunoblotting. RESULTS The analysis of the current literature suggests that the orexin system might be involved in the pathophysiology of absence epilepsy and might be targeted by therapeutic intervention. Experimental data are in line with this hypothesis, showing that OX1 protein levels were reduced in the thalamus and somatosensory cortex of symptomatic WAG/Rij rats (6-7 months of age) with respect to non-epileptic controls, whereas these differences were not seen in pre-symptomatic, 25 days-old WAG/Rij rats. CONCLUSION This perspective might pave the way for future studies on the involvement of the orexinergic system in the pathophysiology of SWDs associated with absence epilepsy and its comorbidities.
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Affiliation(s)
- Roberta Celli
- I.R.C.C.S. Neuromed, Pozzilli, Italy; ,Address correspondence to these authors at the Neuromed, via Dell’Elettronica, 86077 Pozzilli (Is), Italy; Tel: +39 0865915211; E-mail: ; , Donders Centre for Cognition, Radboud University, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands; Tel: +31.24.3615621; E-mail:
| | - Gilles van Luijtelaar
- Donders Centre for Cognition, Radboud University, Nijmegen, The Netherlands,Address correspondence to these authors at the Neuromed, via Dell’Elettronica, 86077 Pozzilli (Is), Italy; Tel: +39 0865915211; E-mail: ; , Donders Centre for Cognition, Radboud University, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands; Tel: +31.24.3615621; E-mail:
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3
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Le N, Sayers S, Mata-Pacheco V, Wagner EJ. The PACAP Paradox: Dynamic and Surprisingly Pleiotropic Actions in the Central Regulation of Energy Homeostasis. Front Endocrinol (Lausanne) 2022; 13:877647. [PMID: 35721722 PMCID: PMC9198406 DOI: 10.3389/fendo.2022.877647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 03/30/2022] [Indexed: 12/11/2022] Open
Abstract
Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP), a pleiotropic neuropeptide, is widely distributed throughout the body. The abundance of PACAP expression in the central and peripheral nervous systems, and years of accompanying experimental evidence, indicates that PACAP plays crucial roles in diverse biological processes ranging from autonomic regulation to neuroprotection. In addition, PACAP is also abundantly expressed in the hypothalamic areas like the ventromedial and arcuate nuclei (VMN and ARC, respectively), as well as other brain regions such as the nucleus accumbens (NAc), bed nucleus of stria terminalis (BNST), and ventral tegmental area (VTA) - suggesting that PACAP is capable of regulating energy homeostasis via both the homeostatic and hedonic energy balance circuitries. The evidence gathered over the years has increased our appreciation for its function in controlling energy balance. Therefore, this review aims to further probe how the pleiotropic actions of PACAP in regulating energy homeostasis is influenced by sex and dynamic changes in energy status. We start with a general overview of energy homeostasis, and then introduce the integral components of the homeostatic and hedonic energy balance circuitries. Next, we discuss sex differences inherent to the regulation of energy homeostasis via these two circuitries, as well as the activational effects of sex steroid hormones that bring about these intrinsic disparities between males and females. Finally, we explore the multifaceted role of PACAP in regulating homeostatic and hedonic feeding through its actions in regions like the NAc, BNST, and in particular the ARC, VMN and VTA that occur in sex- and energy status-dependent ways.
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Affiliation(s)
- Nikki Le
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, United States
| | - Sarah Sayers
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, United States
| | - Veronica Mata-Pacheco
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, United States
| | - Edward J. Wagner
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, United States
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, United States
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4
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Watts AG, Kanoski SE, Sanchez-Watts G, Langhans W. The physiological control of eating: signals, neurons, and networks. Physiol Rev 2022; 102:689-813. [PMID: 34486393 PMCID: PMC8759974 DOI: 10.1152/physrev.00028.2020] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 08/30/2021] [Indexed: 02/07/2023] Open
Abstract
During the past 30 yr, investigating the physiology of eating behaviors has generated a truly vast literature. This is fueled in part by a dramatic increase in obesity and its comorbidities that has coincided with an ever increasing sophistication of genetically based manipulations. These techniques have produced results with a remarkable degree of cell specificity, particularly at the cell signaling level, and have played a lead role in advancing the field. However, putting these findings into a brain-wide context that connects physiological signals and neurons to behavior and somatic physiology requires a thorough consideration of neuronal connections: a field that has also seen an extraordinary technological revolution. Our goal is to present a comprehensive and balanced assessment of how physiological signals associated with energy homeostasis interact at many brain levels to control eating behaviors. A major theme is that these signals engage sets of interacting neural networks throughout the brain that are defined by specific neural connections. We begin by discussing some fundamental concepts, including ones that still engender vigorous debate, that provide the necessary frameworks for understanding how the brain controls meal initiation and termination. These include key word definitions, ATP availability as the pivotal regulated variable in energy homeostasis, neuropeptide signaling, homeostatic and hedonic eating, and meal structure. Within this context, we discuss network models of how key regions in the endbrain (or telencephalon), hypothalamus, hindbrain, medulla, vagus nerve, and spinal cord work together with the gastrointestinal tract to enable the complex motor events that permit animals to eat in diverse situations.
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Affiliation(s)
- Alan G Watts
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Scott E Kanoski
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Graciela Sanchez-Watts
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Wolfgang Langhans
- Physiology and Behavior Laboratory, Eidgenössische Technische Hochschule-Zürich, Schwerzenbach, Switzerland
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5
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Klockars A, Levine AS, Head MA, Perez-Leighton CE, Kotz CM, Olszewski PK. Impact of Gut and Metabolic Hormones on Feeding Reward. Compr Physiol 2021; 11:1425-1447. [PMID: 33577129 DOI: 10.1002/cphy.c190042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Ingestion of food activates a cascade of endocrine responses (thereby reflecting a contemporaneous feeding status) that include the release of hormones from the gastrointestinal (GI) tract, such as cholecystokinin (CCK), glucagonlike peptide YY (PYY), peptide PP, and oleoylethanolamide, as well as suppression of ghrelin secretion. The pancreas and adipose tissue, on the other hand, release hormones that serve as a measure of the current metabolic state or the long-term energy stores, that is, insulin, leptin, and adiponectin. It is well known and intuitively understandable that these hormones target either directly (by crossing the blood-brain barrier) or indirectly (e.g., via vagal input) the "homeostatic" brainstem-hypothalamic pathways involved in the regulation of appetite. The current article focuses on yet another target of the metabolic and GI hormones that is critical in inducing changes in food intake, namely, the reward system. We discuss the physiological basis of this functional interaction, its importance in the control of appetite, and the impact that disruption of this crosstalk has on energy intake in select physiological and pathophysiological states. We conclude that metabolic and GI hormones have a capacity to strengthen or weaken a response of the reward system to a given food, and thus, they are fundamental in ensuring that feeding reward is plastic and dependent on the energy status of the organism. © 2021 American Physiological Society. Compr Physiol 11:1425-1447, 2021.
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Affiliation(s)
- Anica Klockars
- Faculty of Science and Engineering, University of Waikato, Hamilton, New Zealand
| | - Allen S Levine
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA
| | - Mitchell A Head
- Faculty of Science and Engineering, University of Waikato, Hamilton, New Zealand
| | | | - Catherine M Kotz
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA.,Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, USA
| | - Pawel K Olszewski
- Faculty of Science and Engineering, University of Waikato, Hamilton, New Zealand.,Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA.,Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, USA
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6
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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: 5] [Impact Index Per Article: 1.0] [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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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: 20] [Impact Index Per Article: 4.0] [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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8
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Kobashi M, Shimatani Y, Fujita M, Mitoh Y, Yoshida R, Matsuo R. The Effects of Mutual Interaction of Orexin-A and Glucagon-Like Peptide-1 on Reflex Swallowing Induced by SLN Afferents in Rats. Int J Mol Sci 2020; 21:ijms21124422. [PMID: 32580304 PMCID: PMC7352520 DOI: 10.3390/ijms21124422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 06/19/2020] [Accepted: 06/19/2020] [Indexed: 11/16/2022] Open
Abstract
(1) Background: Our previous studies revealed that orexin-A, an appetite-increasing peptide, suppressed reflex swallowing via the commissural part of the nucleus tractus solitarius (cNTS), and that glucagon-like peptide-1 (GLP-1), an appetite-reducing peptide, also suppressed reflex swallowing via the medial nucleus of the NTS (mNTS). In this study, we examined the mutual interaction between orexin-A and GLP-1 in reflex swallowing. (2) Methods: Sprague–Dawley rats under urethane–chloralose anesthesia were used. Swallowing was induced by electrical stimulation of the superior laryngeal nerve (SLN) and was identified by the electromyographic (EMG) signals obtained from the mylohyoid muscle. (3) Results: The injection of GLP-1 (20 pmol) into the mNTS reduced the swallowing frequency and extended the latency of the first swallow. These suppressive effects of GLP-1 were not observed after the fourth ventricular administration of orexin-A. After the injection of an orexin-1 receptor antagonist (SB334867) into the cNTS, an ineffective dose of GLP-1 (6 pmol) into the mNTS suppressed reflex swallowing. Similarly, the suppressive effects of orexin-A (1 nmol) were not observed after the injection of GLP-1 (6 pmol) into the mNTS. After the administration of a GLP-1 receptor antagonist (exendin-4(5-39)), an ineffective dose of orexin-A (0.3 nmol) suppressed reflex swallowing. (4) Conclusions: The presence of reciprocal inhibitory connections between GLP-1 receptive neurons and orexin-A receptive neurons in the NTS was strongly suggested.
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Affiliation(s)
- Motoi Kobashi
- Department of Oral Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan; (M.F.); (Y.M.); (R.Y.); (R.M.)
- Correspondence: ; Tel.: +81-86-235-6641
| | - Yuichi Shimatani
- Department of Medical Engineering, Faculty of Science and Engineering, Tokyo City University, Tokyo 158-8557, Japan;
| | - Masako Fujita
- Department of Oral Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan; (M.F.); (Y.M.); (R.Y.); (R.M.)
| | - Yoshihiro Mitoh
- Department of Oral Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan; (M.F.); (Y.M.); (R.Y.); (R.M.)
| | - Ryusuke Yoshida
- Department of Oral Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan; (M.F.); (Y.M.); (R.Y.); (R.M.)
| | - Ryuji Matsuo
- Department of Oral Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan; (M.F.); (Y.M.); (R.Y.); (R.M.)
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Reppucci CJ, Gergely CK, Bredewold R, Veenema AH. Involvement of orexin/hypocretin in the expression of social play behaviour in juvenile rats. INTERNATIONAL JOURNAL OF PLAY 2020; 9:108-127. [PMID: 33042634 PMCID: PMC7540609 DOI: 10.1080/21594937.2020.1720132] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 01/03/2020] [Indexed: 05/04/2023]
Abstract
Social play is a highly rewarding and motivated behaviour displayed by juveniles of many mammalian species. We hypothesized that the orexin/hypocretin (ORX) system is involved in the expression of juvenile social play behaviour because this system is interconnected with brain regions that comprise the social behaviour and mesocorticolimbic reward networks. We found that exposure to social play increased recruitment of ORX-A neurons in juvenile rats. Furthermore, central administration of ORX-A decreased social play duration, while central blockade of ORX-1 receptors differentially altered social play duration in juvenile rats with low versus high baseline levels of social play (increasing social play in low baseline social play individuals and decreasing social play in high baseline social play individuals). Together, our results provided the first evidence of a role for the ORX system in the modulation of juvenile social play behaviour.
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Affiliation(s)
- Christina J. Reppucci
- Department of Psychology; Neuroscience Program, Michigan State University, East Lansing, MI, USA
- Department of Psychology, Boston College, Chestnut Hill, MA, USA University
| | | | - Remco Bredewold
- Department of Psychology; Neuroscience Program, Michigan State University, East Lansing, MI, USA
- Department of Psychology, Boston College, Chestnut Hill, MA, USA University
| | - Alexa H. Veenema
- Department of Psychology; Neuroscience Program, Michigan State University, East Lansing, MI, USA
- Department of Psychology, Boston College, Chestnut Hill, MA, USA University
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Abstract
Food intake and energy homeostasis determine survival of the organism and species. Information on total energy levels and metabolic state are sensed in the periphery and transmitted to the brain, where it is integrated and triggers the animal to forage, prey, and consume food. Investigating circuitry and cellular mechanisms coordinating energy balance and feeding behaviors has drawn on many state-of-the-art techniques, including gene manipulation, optogenetics, virus tracing, and single-cell sequencing. These new findings provide novel insights into how the central nervous system regulates food intake, and shed the light on potential therapeutic interventions for eating-related disorders such as obesity and anorexia.
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11
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Endocannabinoids in Body Weight Control. Pharmaceuticals (Basel) 2018; 11:ph11020055. [PMID: 29849009 PMCID: PMC6027162 DOI: 10.3390/ph11020055] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 05/17/2018] [Accepted: 05/28/2018] [Indexed: 12/15/2022] Open
Abstract
Maintenance of body weight is fundamental to maintain one's health and to promote longevity. Nevertheless, it appears that the global obesity epidemic is still constantly increasing. Endocannabinoids (eCBs) are lipid messengers that are involved in overall body weight control by interfering with manifold central and peripheral regulatory circuits that orchestrate energy homeostasis. Initially, blocking of eCB signaling by first generation cannabinoid type 1 receptor (CB1) inverse agonists such as rimonabant revealed body weight-reducing effects in laboratory animals and men. Unfortunately, rimonabant also induced severe psychiatric side effects. At this point, it became clear that future cannabinoid research has to decipher more precisely the underlying central and peripheral mechanisms behind eCB-driven control of feeding behavior and whole body energy metabolism. Here, we will summarize the most recent advances in understanding how central eCBs interfere with circuits in the brain that control food intake and energy expenditure. Next, we will focus on how peripheral eCBs affect food digestion, nutrient transformation and energy expenditure by interfering with signaling cascades in the gastrointestinal tract, liver, pancreas, fat depots and endocrine glands. To finally outline the safe future potential of cannabinoids as medicines, our overall goal is to address the molecular, cellular and pharmacological logic behind central and peripheral eCB-mediated body weight control, and to figure out how these precise mechanistic insights are currently transferred into the development of next generation cannabinoid medicines displaying clearly improved safety profiles, such as significantly reduced side effects.
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12
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Hsu TM, McCutcheon JE, Roitman MF. Parallels and Overlap: The Integration of Homeostatic Signals by Mesolimbic Dopamine Neurons. Front Psychiatry 2018; 9:410. [PMID: 30233430 PMCID: PMC6129766 DOI: 10.3389/fpsyt.2018.00410] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 08/13/2018] [Indexed: 01/08/2023] Open
Abstract
Motivated behaviors are often initiated in response to perturbations of homeostasis. Indeed, animals and humans have fundamental drives to procure (appetitive behaviors) and eventually ingest (consummatory behaviors) substances based on deficits in body fluid (e.g., thirst) and energy balance (e.g., hunger). Consumption, in turn, reinforces motivated behavior and is therefore considered rewarding. Over the years, the constructs of homeostatic (within the purview of the hypothalamus) and reward (within the purview of mesolimbic circuitry) have been used to describe need-based vs. need-free consumption. However, many experiments have demonstrated that mesolimbic circuits and "higher-order" brain regions are also profoundly influenced by changes to physiological state, which in turn generate behaviors that are poised to maintain homeostasis. Mesolimbic pathways, particularly dopamine neurons of the ventral tegmental area (VTA) and their projections to nucleus accumbens (NAc), can be robustly modulated by a variety of energy balance signals, including post-ingestive feedback relaying nutrient content and hormonal signals reflecting hunger and satiety. Moreover, physiological states can also impact VTA-NAc responses to non-nutritive rewards, such as drugs of abuse. Coupled with recent evidence showing hypothalamic structures are modulated in anticipation of replenished need, classic boundaries between circuits that convey perturbations in homeostasis and those that drive motivated behavior are being questioned. In the current review, we examine data that have revealed the importance of mesolimbic dopamine neurons and their downstream pathways as a dynamic neurobiological mechanism that provides an interface between physiological state, perturbations to homeostasis, and reward-seeking behaviors.
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Affiliation(s)
- Ted M Hsu
- Department of Psychology, University of Illinois at Chicago, Chicago, IL, United States
| | - James E McCutcheon
- Department of Neuroscience, Psychology and Behavior, University of Leicester, Leicester, United Kingdom
| | - Mitchell F Roitman
- Department of Psychology, University of Illinois at Chicago, Chicago, IL, United States
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13
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Abstract
Understanding of the neural and physiological substrates of hunger and satiety has increased rapidly over the last three decades, and pharmacological targets have already been identified for the treatment of obesity that has moved from pre-clinical screening to therapies approved by regulatory authorities. Initially, this review describes the way in which physiological signals of energy availability interact with hedonic and rewarding properties of food to modulate the neural circuitry that supports eating behaviour. This is followed by a brief account of current and promising targets for drug development and a review of the wide range of preclinical paradigms that model important influences on human eating behaviour, and can be used to guide early stages of the drug development process.
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14
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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: 4.0] [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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15
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Tabe-Bordbar S, Anastasio TJ. Computational Analysis of the Hypothalamic Control of Food Intake. Front Comput Neurosci 2016; 10:27. [PMID: 27199725 PMCID: PMC4844610 DOI: 10.3389/fncom.2016.00027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 03/14/2016] [Indexed: 12/01/2022] Open
Abstract
Food-intake control is mediated by a heterogeneous network of different neural subtypes, distributed over various hypothalamic nuclei and other brain structures, in which each subtype can release more than one neurotransmitter or neurohormone. The complexity of the interactions of these subtypes poses a challenge to understanding their specific contributions to food-intake control, and apparent consistencies in the dataset can be contradicted by new findings. For example, the growing consensus that arcuate nucleus neurons expressing Agouti-related peptide (AgRP neurons) promote feeding, while those expressing pro-opiomelanocortin (POMC neurons) suppress feeding, is contradicted by findings that low AgRP neuron activity and high POMC neuron activity can be associated with high levels of food intake. Similarly, the growing consensus that GABAergic neurons in the lateral hypothalamus suppress feeding is contradicted by findings suggesting the opposite. Yet the complexity of the food-intake control network admits many different network behaviors. It is possible that anomalous associations between the responses of certain neural subtypes and feeding are actually consistent with known interactions, but their effect on feeding depends on the responses of the other neural subtypes in the network. We explored this possibility through computational analysis. We made a computer model of the interactions between the hypothalamic and other neural subtypes known to be involved in food-intake control, and optimized its parameters so that model behavior matched observed behavior over an extensive test battery. We then used specialized computational techniques to search the entire model state space, where each state represents a different configuration of the responses of the units (model neural subtypes) in the network. We found that the anomalous associations between the responses of certain hypothalamic neural subtypes and feeding are actually consistent with the known structure of the food-intake control network, and we could specify the ways in which the anomalous configurations differed from the expected ones. By analyzing the temporal relationships between different states we identified the conditions under which the anomalous associations can occur, and these stand as model predictions.
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Affiliation(s)
- Shayan Tabe-Bordbar
- Computational Neurobiology Laboratory, Department of Molecular and Integrative Physiology, Beckman Institute, University of Illinois at Urbana-Champaign Urbana, IL, USA
| | - Thomas J Anastasio
- Computational Neurobiology Laboratory, Department of Molecular and Integrative Physiology, Beckman Institute, University of Illinois at Urbana-Champaign Urbana, IL, USA
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16
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Hsu TM, Suarez AN, Kanoski SE. Ghrelin: A link between memory and ingestive behavior. Physiol Behav 2016; 162:10-7. [PMID: 27072509 DOI: 10.1016/j.physbeh.2016.03.039] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/29/2016] [Accepted: 03/31/2016] [Indexed: 01/25/2023]
Abstract
Feeding is a highly complex behavior that is influenced by learned associations between external and internal cues. The type of excessive feeding behavior contributing to obesity onset and metabolic deficit may be based, in part, on conditioned appetitive and ingestive behaviors that occur in response to environmental and/or interoceptive cues associated with palatable food. Therefore, there is a critical need to understand the neurobiology underlying learned aspects of feeding behavior. The stomach-derived "hunger" hormone, ghrelin, stimulates appetite and food intake and may function as an important biological substrate linking mnemonic processes with feeding control. The current review highlights data supporting a role for ghrelin in mediating the cognitive and neurobiological mechanisms that underlie conditioned feeding behavior. We discuss the role of learning and memory on food intake control (with a particular focus on hippocampal-dependent memory processes) and provide an overview of conditioned cephalic endocrine responses. A neurobiological framework is provided through which conditioned cephalic ghrelin secretion signals in neurons in the hippocampus, which then engage orexigenic neural circuitry in the lateral hypothalamus to express learned feeding behavior.
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Affiliation(s)
- Ted M Hsu
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA; Neuroscience Program, University of Southern California, Los Angeles, CA, USA
| | - Andrea N Suarez
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Scott E Kanoski
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA; Neuroscience Program, University of Southern California, Los Angeles, CA, USA.
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17
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Hsu TM, Hahn JD, Konanur VR, Noble EE, Suarez AN, Thai J, Nakamoto EM, Kanoski SE. Hippocampus ghrelin signaling mediates appetite through lateral hypothalamic orexin pathways. eLife 2015; 4. [PMID: 26745307 PMCID: PMC4695382 DOI: 10.7554/elife.11190] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 11/06/2015] [Indexed: 12/14/2022] Open
Abstract
Feeding behavior rarely occurs in direct response to metabolic deficit, yet the overwhelming majority of research on the biology of food intake control has focused on basic metabolic and homeostatic neurobiological substrates. Most animals, including humans, have habitual feeding patterns in which meals are consumed based on learned and/or environmental factors. Here we illuminate a novel neural system regulating higher-order aspects of feeding through which the gut-derived hormone ghrelin communicates with ventral hippocampus (vHP) neurons to stimulate meal-entrained conditioned appetite. Additional results show that the lateral hypothalamus (LHA) is a critical downstream substrate for vHP ghrelin-mediated hyperphagia and that vHP ghrelin activated neurons communicate directly with neurons in the LHA that express the neuropeptide, orexin. Furthermore, activation of downstream orexin-1 receptors is required for vHP ghrelin-mediated hyperphagia. These findings reveal novel neurobiological circuitry regulating appetite through which ghrelin signaling in hippocampal neurons engages LHA orexin signaling.
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Affiliation(s)
- Ted M Hsu
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, United States.,Neuroscience Program, University of Southern California, Los Angeles, United States
| | - Joel D Hahn
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, United States
| | - Vaibhav R Konanur
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, United States
| | - Emily E Noble
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, United States
| | - Andrea N Suarez
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, United States
| | - Jessica Thai
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, United States
| | - Emily M Nakamoto
- Neuroscience Program, University of Southern California, Los Angeles, United States
| | - Scott E Kanoski
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, United States.,Neuroscience Program, University of Southern California, Los Angeles, United States
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18
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Abstract
The essential role of the brain in maintaining energy homeostasis has motivated the drive to define the neural circuitry that integrates external and internal stimuli to enact appropriate and consequential metabolic and behavioral responses. The hypothalamus has received significant attention in this regard given its ability to influence feeding behavior, yet organisms rely on a much broader diversity and distribution of neuronal networks to regulate both energy intake and expenditure. Because energy balance is a fundamental determinant of survival and success of an organism, it is not surprising that emerging data connect circuits controlling feeding and energy balance with higher brain functions and degenerative processes. In this review, we will highlight both classically defined and emerging aspects of brain control of energy homeostasis.
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Affiliation(s)
- Michael J Waterson
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Tamas L Horvath
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520, USA.
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19
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Li AJ, Wang Q, Elsarelli MM, Brown RL, Ritter S. Hindbrain Catecholamine Neurons Activate Orexin Neurons During Systemic Glucoprivation in Male Rats. Endocrinology 2015; 156:2807-20. [PMID: 25978516 PMCID: PMC5393341 DOI: 10.1210/en.2015-1138] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Hindbrain catecholamine neurons are required for elicitation of feeding responses to glucose deficit, but the forebrain circuitry required for these responses is incompletely understood. Here we examined interactions of catecholamine and orexin neurons in eliciting glucoprivic feeding. Orexin neurons, located in the perifornical lateral hypothalamus (PeFLH), are heavily innervated by hindbrain catecholamine neurons, stimulate food intake, and increase arousal and behavioral activation. Orexin neurons may therefore contribute importantly to appetitive responses, such as food seeking, during glucoprivation. Retrograde tracing results showed that nearly all innervation of the PeFLH from the hindbrain originated from catecholamine neurons and some raphe nuclei. Results also suggested that many catecholamine neurons project collaterally to the PeFLH and paraventricular hypothalamic nucleus. Systemic administration of the antiglycolytic agent, 2-deoxy-D-glucose, increased food intake and c-Fos expression in orexin neurons. Both responses were eliminated by a lesion of catecholamine neurons innervating orexin neurons using the retrogradely transported immunotoxin, anti-dopamine-β-hydroxylase saporin, which is specifically internalized by dopamine-β-hydroxylase-expressing catecholamine neurons. Using designer receptors exclusively activated by designer drugs in transgenic rats expressing Cre recombinase under the control of tyrosine hydroxylase promoter, catecholamine neurons in cell groups A1 and C1 of the ventrolateral medulla were activated selectively by peripheral injection of clozapine-N-oxide. Clozapine-N-oxide injection increased food intake and c-Fos expression in PeFLH orexin neurons as well as in paraventricular hypothalamic nucleus neurons. In summary, catecholamine neurons are required for the activation of orexin neurons during glucoprivation. Activation of orexin neurons may contribute to appetitive responses required for glucoprivic feeding.
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Affiliation(s)
- Ai-Jun Li
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - Qing Wang
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - Megan M Elsarelli
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - R Lane Brown
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - Sue Ritter
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
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20
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Carvajal F, Alcaraz-Iborra M, Lerma-Cabrera JM, Valor LM, de la Fuente L, Sanchez-Amate MDC, Cubero I. Orexin receptor 1 signaling contributes to ethanol binge-like drinking: Pharmacological and molecular evidence. Behav Brain Res 2015; 287:230-7. [DOI: 10.1016/j.bbr.2015.03.046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 03/03/2015] [Accepted: 03/22/2015] [Indexed: 12/27/2022]
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21
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Li AJ, Wang Q, Davis H, Wang R, Ritter S. Orexin-A enhances feeding in male rats by activating hindbrain catecholamine neurons. Am J Physiol Regul Integr Comp Physiol 2015; 309:R358-67. [PMID: 26062632 DOI: 10.1152/ajpregu.00065.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 06/05/2015] [Indexed: 11/22/2022]
Abstract
Both lateral hypothalamic orexinergic neurons and hindbrain catecholaminergic neurons contribute to control of feeding behavior. Orexin fibers and terminals are present in close proximity to hindbrain catecholaminergic neurons, and fourth ventricular (4V) orexin injections that increase food intake also increase c-Fos expression in hindbrain catecholamine neurons, suggesting that orexin neurons may stimulate feeding by activating catecholamine neurons. Here we examine that hypothesis in more detail. We found that 4V injection of orexin-A (0.5 nmol/rat) produced widespread activation of c-Fos in hindbrain catecholamine cell groups. In the A1 and C1 cell groups in the ventrolateral medulla, where most c-Fos-positive neurons were also dopamine β hydroxylase (DBH) positive, direct injections of a lower dose (67 pmol/200 nl) of orexin-A also increased food intake in intact rats. Then, with the use of the retrogradely transported immunotoxin, anti-DBH conjugated to saporin (DSAP), which targets and destroys DBH-expressing catecholamine neurons, we examined the hypothesis that catecholamine neurons are required for orexin-induced feeding. Rats given paraventricular hypothalamic injections of DSAP, or unconjugated saporin (SAP) as control, were implanted with 4V or lateral ventricular (LV) cannulas and tested for feeding in response to ventricular injection of orexin-A (0.5 nmol/rat). Both LV and 4V orexin-A stimulated feeding in SAP controls, but DSAP abolished these responses. These results reveal for the first time that catecholamine neurons are required for feeding induced by injection of orexin-A into either LV or 4V.
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Affiliation(s)
- Ai-Jun Li
- Programs in Neuroscience, Washington State University, Pullman, Washington
| | - Qing Wang
- Programs in Neuroscience, Washington State University, Pullman, Washington
| | - Hana Davis
- Programs in Neuroscience, Washington State University, Pullman, Washington
| | - Rong Wang
- Programs in Neuroscience, Washington State University, Pullman, Washington
| | - Sue Ritter
- Programs in Neuroscience, Washington State University, Pullman, Washington
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22
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Williams DL. Neural integration of satiation and food reward: role of GLP-1 and orexin pathways. Physiol Behav 2014; 136:194-9. [PMID: 24650552 PMCID: PMC4167985 DOI: 10.1016/j.physbeh.2014.03.013] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 02/23/2014] [Accepted: 03/10/2014] [Indexed: 02/07/2023]
Abstract
Central nervous system control of food intake involves detecting, integrating and responding to diverse internal and external signals. For maintenance of energy homeostasis, the brain uses long-term signals of metabolic status and short-term signals related to the nutrient content of individual meals. Feeding is also clearly influenced by hedonic, reward-related factors: palatability, motivation, and learned associations and cues that predict the availability of food. Different neural circuits have been proposed to mediate these homeostatic and hedonic aspects of eating. This review describes research on neural pathways that appear to be involved in both, integrating gastrointestinal satiation signaling with food reward. First, the glucagon-like peptide 1 projections from the nucleus of the solitary tract to the nucleus accumbens and ventral tegmental area are discussed as a mechanism through which meal-related gut signals may influence palatability, motivation for food, and meal size. Second, the orexin projection from lateral hypothalamus to the nucleus of the solitary tract and area postrema is discussed as a mechanism through which cues that predict rewarding food may act to increase motivation for food and also to suppress satiation. Additional potential integrative sites and pathways are also briefly discussed. Based on these findings, it is suggested that the brain circuitry involved in energy homeostasis and the circuitry mediating food reward are, in fact, overlapping and far less distinct than previously considered.
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Affiliation(s)
- Diana L Williams
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL, USA.
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23
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Darwinkel A, Stanić D, Booth LC, May CN, Lawrence AJ, Yao ST. Distribution of orexin-1 receptor-green fluorescent protein- (OX1-GFP) expressing neurons in the mouse brain stem and pons: Co-localization with tyrosine hydroxylase and neuronal nitric oxide synthase. Neuroscience 2014; 278:253-64. [PMID: 25168728 DOI: 10.1016/j.neuroscience.2014.08.027] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 08/13/2014] [Accepted: 08/14/2014] [Indexed: 11/16/2022]
Abstract
We used a reporter mouse line in which green fluorescent protein (GFP) was inserted into the orexin-1 receptor (OX1) locus to systematically map the neuroanatomical distribution of the OX1 receptor in the mouse brainstem and pons. Here, we show that the OX1 receptor is expressed in a select subset of medullary and pontine nuclei. In the medulla, we observed OX1-GFP expression in the cuneate, gracile, dorsal motor nucleus of the vagus (10N), nucleus of the solitary tract and medullary raphe areas. In the pons, the greatest expression was found in the locus coeruleus (LC) and dorsal raphe nucleus (DRN). High to moderate expression was found in the pedunculopontine tegmental nucleus (PPTg), laterodorsal tegmental nucleus, A5 noradrenergic cell group (A5) and the periaqueductal gray. Double-labeling with neuronal nitric oxide synthase (NOS1) revealed extensive co-localization in cell bodies and fibers of the 10N, A5 cell group and the PPTg. Double-staining with tyrosine hydroxylase revealed extensive co-expression in the LC, DRN and the lateral paragigantocellularis cell group in the ventral medulla. Our findings faithfully recapitulate the findings of OX1 mRNA expression previously reported. This is the first study to systematically map the neuroanatomical distribution of OX1 receptors within the mouse hindbrain and suggest that this OX1-GFP transgenic reporter mouse line might be a useful tool with which to study the neuroanatomy and physiology of OX1 receptor-expressing cells.
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Affiliation(s)
- A Darwinkel
- Florey Institute of Neuroscience and Mental Health, Howard Florey Laboratories, University of Melbourne, Royal Parade, VIC 3010, Australia
| | - D Stanić
- Florey Institute of Neuroscience and Mental Health, Howard Florey Laboratories, University of Melbourne, Royal Parade, VIC 3010, Australia
| | - L C Booth
- Florey Institute of Neuroscience and Mental Health, Howard Florey Laboratories, University of Melbourne, Royal Parade, VIC 3010, Australia
| | - C N May
- Florey Institute of Neuroscience and Mental Health, Howard Florey Laboratories, University of Melbourne, Royal Parade, VIC 3010, Australia
| | - A J Lawrence
- Florey Institute of Neuroscience and Mental Health, Howard Florey Laboratories, University of Melbourne, Royal Parade, VIC 3010, Australia
| | - S T Yao
- Florey Institute of Neuroscience and Mental Health, Howard Florey Laboratories, University of Melbourne, Royal Parade, VIC 3010, Australia.
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24
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Hypothalamic orexin-A (hypocretin-1) neuronal projections to the vestibular complex and cerebellum in the rat. Brain Res 2014; 1579:20-34. [PMID: 25017945 DOI: 10.1016/j.brainres.2014.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 06/24/2014] [Accepted: 07/04/2014] [Indexed: 12/31/2022]
Abstract
Immunohistochemistry combined with retrograde tract-tracing techniques were used to investigate the distribution of orexin-A (OX-A)- and OX-A receptor-like (OX1) immunoreactivity within the vestibular complex and cerebellum, and the location of hypothalamic OX-A neurons sending axonal projections to these regions in the Wistar rat. OX-A immunoreactive fibers and presumptive terminals were found throughout the medial (MVe) and lateral (LVe) vestibular nuclei. Light fiber labeling was also observed in the spinal and superior vestibular nuclei. Within the cerebellum, dense fiber and presumptive terminal labeling was observed in the medial cerebellar nucleus (Med; fastigial nucleus), with less dense labeling in the interposed (Int) and lateral cerebellar nuclei (Lat; dentate nucleus). A few scattered OX-A immunoreactive fibers were also observed throughout the cortex of the paraflocculus. OX1-like immunoreactivity was found densely concentrated within LVe, moderate in MVe, and scattered within the spinal and superior vestibular nuclei. Within the cerebellum, OX1-like immunoreactivity was also observed densely within Med and in the dorsolateral aspects of Int. Additionally, OX1 like-labeling was found in Lat, and within the granular layer of the caudal paraflocculus cerebellar cortex. Fluorogold (FG) microinjected into these vestibular and cerebellar regions resulted in retrogradely labeled neurons throughout the ipsilateral hypothalamus. Retrogradely labeled neurons containing OX-A like immunoreactivity were observed dorsal and caudal to the anterior hypothalamic nucleus and extending laterally into the lateral hypothalamic area, with the largest number clustered around the dorsal aspects of the fornix in the perifornical area. A few FG OX-A like-immunoreactive neurons were also observed scattered throughout the dorsomedial, and posterior hypothalamic nuclei. These data indicate that axons from OX-A neurons terminate within the vestibular complex and deep cerebellar nuclei of the cerebellum and although the function of these pathways is unknown, they likely represent pathways by which hypothalamic OX-A containing neurons co-ordinate vestibulo-cerebellar motor and autonomic functions associated with ingestive behaviors.
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25
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Karasawa H, Yakabi S, Wang L, Taché Y. Orexin-1 receptor mediates the increased food and water intake induced by intracerebroventricular injection of the stable somatostatin pan-agonist, ODT8-SST in rats. Neurosci Lett 2014; 576:88-92. [PMID: 24915296 DOI: 10.1016/j.neulet.2014.05.063] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 05/25/2014] [Accepted: 05/31/2014] [Indexed: 11/19/2022]
Abstract
Intracerebroventricular (icv) injection of the stable somatostatin pan-agonist, ODT8-SST induces a somatostatin 2 receptor (sst2) mediated robust feeding response that involves neuropeptide Y and opioid systems in rats. We investigated whether the orexigenic system driven by orexin also plays a role. Food and water intake after icv injection was measured concomitantly in non-fasted and non-water deprived rats during the light phase. In vehicle treated rats (100% DMSO, icv), ODT8-SST (1μg/rat, icv) significantly increased the 2-h food and water intake compared to icv vehicle plus saline (5.1±1.0g vs. 1.2±0.4g and 11.3±1.9mL vs. 2.5±1.2mL, respectively). The orexin-1 receptor antagonist, SB-334867 (16μg/rat, icv) completely inhibited the 2-h food and water intake induced by icv ODT8-SST. In contrast, the icv pretreatment with the selective somatostatin sst2 antagonist, S-406-028, established to block the orexigenic effect of icv ODT8-SST, did not modify the increased food and water intake induced by icv orexin-A (10.7μg/rat). These data indicate that orexin-1 receptor signaling system is part of the brain neurocircuitry contributing to the orexigenic and dipsogenic responses induced by icv ODT8-SST and that orexin-A stimulates food intake independently from brain sst2 activation.
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Affiliation(s)
- Hiroshi Karasawa
- Department of Medicine, CURE/Digestive Diseases Center, and Center for Neurobiology of Stress Digestive Diseases Division, University of California at Los Angeles, Los Angeles, CA 90073, USA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | - Seiichi Yakabi
- Department of Medicine, CURE/Digestive Diseases Center, and Center for Neurobiology of Stress Digestive Diseases Division, University of California at Los Angeles, Los Angeles, CA 90073, USA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | - Lixin Wang
- Department of Medicine, CURE/Digestive Diseases Center, and Center for Neurobiology of Stress Digestive Diseases Division, University of California at Los Angeles, Los Angeles, CA 90073, USA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | - Yvette Taché
- Department of Medicine, CURE/Digestive Diseases Center, and Center for Neurobiology of Stress Digestive Diseases Division, University of California at Los Angeles, Los Angeles, CA 90073, USA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA.
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26
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Asevedo E, Rizzo LB, Gadelha A, Mansur RB, Ota VK, Berberian AA, Scarpato BS, Teixeira AL, Bressan RA, Brietzke E. Peripheral interleukin-2 level is associated with negative symptoms and cognitive performance in schizophrenia. Physiol Behav 2014; 129:194-8. [PMID: 24576679 DOI: 10.1016/j.physbeh.2014.02.032] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Revised: 10/07/2013] [Accepted: 02/12/2014] [Indexed: 01/13/2023]
Abstract
Although several studies have pointed to a possible role of interleukin 2 (IL-2) in schizophrenia (SZ), association between IL-2 and the different groups of symptoms has not been explored. The objective of this study was to investigate a possible correlation of peripheral IL-2 levels with symptoms and cognitive performance in patients with SZ. In addition, we compared the plasma levels of IL-2 between patients with SZ and healthy controls. Twenty-nine chronically medicated outpatients with SZ according to DSM-IV were compared with twenty-six healthy controls. The patients were evaluated with the Positive and Negative Syndrome Scale (PANSS), the Calgary Depression Scale for Schizophrenia (CDSS), the Clinical Global Impression (CGI) and the Global Assessment of Functioning (GAF). All the participants had blood collected into EDTA tubes by venipuncture between 9:00 and 10:00AM. Plasma concentrations of IL-2 were determined by cytometric bead array. A computerized neuropsychological battery assessed verbal learning, verbal fluency, working memory, set shifting, executive function, inhibition and intelligence. Patients with SZ had lower levels of IL-2 than healthy controls (p<0.001). In the SZ group, IL-2 levels were positively correlated with scores in the digit span test (rho=0.416, P=0.025) and intelligence (rho=0.464, P=0.011). We also found a negative correlation between IL-2 and total score in the negative subscale of PANSS (rho=-0.447, p=0.015). Our findings suggest that IL-2 may be involved in the mechanisms related to cognitive deterioration and negative symptomatology in schizophrenia.
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Affiliation(s)
- Elson Asevedo
- Schizophrenia Program (PROESQ), Department of Psychiatry, Federal University of São Paulo, Rua Machado Bittencourt, 222, São Paulo, SP, CEP 04044-000, Brazil; Interdisciplinary Laboratory of Clinical Neurosciences (LINC), Department of Psychiatry, Federal University of São Paulo, Rua Pedro de Toledo, 669, Edifício de Pesquisas II, third floor, São Paulo SP, CEP 04039-032, Brazil.
| | - Lucas B Rizzo
- Interdisciplinary Laboratory of Clinical Neurosciences (LINC), Department of Psychiatry, Federal University of São Paulo, Rua Pedro de Toledo, 669, Edifício de Pesquisas II, third floor, São Paulo SP, CEP 04039-032, Brazil.
| | - Ary Gadelha
- Schizophrenia Program (PROESQ), Department of Psychiatry, Federal University of São Paulo, Rua Machado Bittencourt, 222, São Paulo, SP, CEP 04044-000, Brazil; Interdisciplinary Laboratory of Clinical Neurosciences (LINC), Department of Psychiatry, Federal University of São Paulo, Rua Pedro de Toledo, 669, Edifício de Pesquisas II, third floor, São Paulo SP, CEP 04039-032, Brazil.
| | - Rodrigo B Mansur
- Interdisciplinary Laboratory of Clinical Neurosciences (LINC), Department of Psychiatry, Federal University of São Paulo, Rua Pedro de Toledo, 669, Edifício de Pesquisas II, third floor, São Paulo SP, CEP 04039-032, Brazil.
| | - Vanessa K Ota
- Interdisciplinary Laboratory of Clinical Neurosciences (LINC), Department of Psychiatry, Federal University of São Paulo, Rua Pedro de Toledo, 669, Edifício de Pesquisas II, third floor, São Paulo SP, CEP 04039-032, Brazil.
| | - Arthur A Berberian
- Schizophrenia Program (PROESQ), Department of Psychiatry, Federal University of São Paulo, Rua Machado Bittencourt, 222, São Paulo, SP, CEP 04044-000, Brazil; Interdisciplinary Laboratory of Clinical Neurosciences (LINC), Department of Psychiatry, Federal University of São Paulo, Rua Pedro de Toledo, 669, Edifício de Pesquisas II, third floor, São Paulo SP, CEP 04039-032, Brazil.
| | - Bruno S Scarpato
- Interdisciplinary Laboratory of Clinical Neurosciences (LINC), Department of Psychiatry, Federal University of São Paulo, Rua Pedro de Toledo, 669, Edifício de Pesquisas II, third floor, São Paulo SP, CEP 04039-032, Brazil.
| | - Antônio L Teixeira
- Translational Psychoneuroimmunology Group, Federal University of Minas Gerais, Avenida Antonio Carlos, 6627, Pampulha, Belo Horizonte MG, CEP 31270-901, Brazil.
| | - Rodrigo A Bressan
- Schizophrenia Program (PROESQ), Department of Psychiatry, Federal University of São Paulo, Rua Machado Bittencourt, 222, São Paulo, SP, CEP 04044-000, Brazil; Interdisciplinary Laboratory of Clinical Neurosciences (LINC), Department of Psychiatry, Federal University of São Paulo, Rua Pedro de Toledo, 669, Edifício de Pesquisas II, third floor, São Paulo SP, CEP 04039-032, Brazil.
| | - Elisa Brietzke
- Interdisciplinary Laboratory of Clinical Neurosciences (LINC), Department of Psychiatry, Federal University of São Paulo, Rua Pedro de Toledo, 669, Edifício de Pesquisas II, third floor, São Paulo SP, CEP 04039-032, Brazil.
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Schneeberger M, Gomis R, Claret M. Hypothalamic and brainstem neuronal circuits controlling homeostatic energy balance. J Endocrinol 2014; 220:T25-46. [PMID: 24222039 DOI: 10.1530/joe-13-0398] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Alterations in adequate energy balance maintenance result in serious metabolic disturbances such as obesity. In mammals, this complex process is orchestrated by multiple and distributed neuronal circuits. Hypothalamic and brainstem neuronal circuits are critically involved in the sensing of circulating and local factors conveying information about the energy status of the organism. The integration of these signals culminates in the generation of specific and coordinated physiological responses aimed at regulating energy balance through the modulation of appetite and energy expenditure. In this article, we review current knowledge on the homeostatic regulation of energy balance, emphasizing recent advances in mouse genetics, electrophysiology, and optogenetic techniques that have greatly contributed to improving our understanding of this central process.
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Affiliation(s)
- Marc Schneeberger
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain Department of Endocrinology and Nutrition, School of Medicine, Hospital Clínic, University of Barcelona, 08036 Barcelona, Spain Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 08036 Barcelona, Spain
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Kay K, Parise EM, Lilly N, Williams DL. Hindbrain orexin 1 receptors influence palatable food intake, operant responding for food, and food-conditioned place preference in rats. Psychopharmacology (Berl) 2014; 231:419-27. [PMID: 23978908 PMCID: PMC3946976 DOI: 10.1007/s00213-013-3248-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 08/08/2013] [Indexed: 10/26/2022]
Abstract
RATIONALE Brain orexin 1 receptors (OX1Rs) are involved in food-motivated behavior. Most research has focused on forebrain OX1R populations, but hindbrain OX1Rs affect feeding. We hypothesized that hindbrain OX1Rs affect the reward value of food. OBJECTIVES We examined the effects of hindbrain OX1R stimulation or blockade on motivation for food, palatable high-fat (HF) food intake, and food-conditioned place preference. METHODS Rats trained to lever press for sucrose on a progressive ratio (PR) schedule received fourth intracerebroventricular (icv) injections of vehicle, orexin-A (0.1-1 nmol), or the OX1R antagonist SB334867 (10-20 nmol) before operant test sessions. Effects of these treatments on HF food intake during daily 1-h tests were assessed with fourth icv and nucleus of the solitary tract (NTS) injections. We conditioned a place preference by pairing HF food with one side of a two-sided chamber and then examined the effect of 20 nmol fourth icv SB334867 on the expression of that preference. RESULTS In ad lib fed rats on the PR schedule, fourth icv orexin-A significantly increased responding and breakpoint relative to the vehicle. In 24-h food-deprived rats, fourth icv SB334867 significantly decreased responding and breakpoint. Orexin-A delivered to the fourth ventricle (0.1 nmol) or NTS (0.01 nmol) increased HF diet intake. Fourth icv SB334867 did not affect HF food intake, but SB334867 delivered either fourth icv (20 nmol) or intra-NTS (5-10 nmol) suppressed chow intake. Expression of HF food-conditioned place preference was inhibited by fourth icv SB334867. CONCLUSIONS Hindbrain OX1R activity affects food-motivated operant behavior and may play a role in responding to cues that predict palatable food.
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Affiliation(s)
- Kristen Kay
- Department of Psychology and Program in Neuroscience, Florida State
University, Box 3064301, Tallahassee, FL 32306-4301, USA
| | - Eric M. Parise
- Department of Psychology and Program in Neuroscience, Florida State
University, Box 3064301, Tallahassee, FL 32306-4301, USA
| | - Nicole Lilly
- Department of Psychology and Program in Neuroscience, Florida State
University, Box 3064301, Tallahassee, FL 32306-4301, USA
| | - Diana L. Williams
- Department of Psychology and Program in Neuroscience, Florida State
University, Box 3064301, Tallahassee, FL 32306-4301, USA
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Steiner MA, Sciarretta C, Pasquali A, Jenck F. The selective orexin receptor 1 antagonist ACT-335827 in a rat model of diet-induced obesity associated with metabolic syndrome. Front Pharmacol 2013; 4:165. [PMID: 24416020 PMCID: PMC3874552 DOI: 10.3389/fphar.2013.00165] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 12/13/2013] [Indexed: 02/04/2023] Open
Abstract
The orexin system regulates feeding, nutrient metabolism and energy homeostasis. Acute pharmacological blockade of orexin receptor 1 (OXR-1) in rodents induces satiety and reduces normal and palatable food intake. Genetic OXR-1 deletion in mice improves hyperglycemia under high-fat (HF) diet conditions. Here we investigated the effects of chronic treatment with the novel selective OXR-1 antagonist ACT-335827 in a rat model of diet-induced obesity (DIO) associated with metabolic syndrome (MetS). Rats were fed either standard chow (SC) or a cafeteria (CAF) diet comprised of intermittent human snacks and a constant free choice between a HF/sweet (HF/S) diet and SC for 13 weeks. Thereafter the SC group was treated with vehicle (for 4 weeks) and the CAF group was divided into a vehicle and an ACT-335827 treatment group. Energy and water intake, food preference, and indicators of MetS (abdominal obesity, glucose homeostasis, plasma lipids, and blood pressure) were monitored. Hippocampus-dependent memory, which can be impaired by DIO, was assessed. CAF diet fed rats treated with ACT-335827 consumed less of the HF/S diet and more of the SC, but did not change their snack or total kcal intake compared to vehicle-treated rats. ACT-335827 increased water intake and the high-density lipoprotein associated cholesterol proportion of total circulating cholesterol. ACT-335827 slightly increased body weight gain (4% vs. controls) and feed efficiency in the absence of hyperphagia. These effects were not associated with significant changes in the elevated fasting glucose and triglyceride (TG) plasma levels, glucose intolerance, elevated blood pressure, and adiposity due to CAF diet consumption. Neither CAF diet consumption alone nor ACT-335827 affected memory. In conclusion, the main metabolic characteristics associated with DIO and MetS in rats remained unaffected by chronic ACT-335827 treatment, suggesting that pharmacological OXR-1 blockade has minimal impact in this model.
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Affiliation(s)
- Michel A Steiner
- CNS Pharmacology Neurobiology, Actelion Pharmaceuticals Ltd. Allschwil, Switzerland
| | - Carla Sciarretta
- Immunology, Actelion Pharmaceuticals Ltd. Allschwil, Switzerland
| | - Anne Pasquali
- Cardiology, Actelion Pharmaceuticals Ltd. Allschwil, Switzerland
| | - Francois Jenck
- CNS Pharmacology Neurobiology, Actelion Pharmaceuticals Ltd. Allschwil, Switzerland
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Abstract
Body weight is determined by a balance between food intake and energy expenditure. Multiple neural circuits in the brain have evolved to process information about food, food-related cues and food consumption to control feeding behavior. Numerous gastrointestinal endocrine cells produce and secrete satiety hormones in response to food consumption and digestion. These hormones suppress hunger and promote satiation and satiety mainly through hindbrain circuits, thus governing meal-by-meal eating behavior. In contrast, the hypothalamus integrates adiposity signals to regulate long-term energy balance and body weight. Distinct hypothalamic areas and various orexigenic and anorexigenic neurons have been identified to homeostatically regulate food intake. The hypothalamic circuits regulate food intake in part by modulating the sensitivity of the hindbrain to short-term satiety hormones. The hedonic and incentive properties of foods and food-related cues are processed by the corticolimbic reward circuits. The mesolimbic dopamine system encodes subjective "liking" and "wanting" of palatable foods, which is subjected to modulation by the hindbrain and the hypothalamic homeostatic circuits and by satiety and adiposity hormones. Satiety and adiposity hormones also promote energy expenditure by stimulating brown adipose tissue (BAT) activity. They stimulate BAT thermogenesis mainly by increasing the sympathetic outflow to BAT. Many defects in satiety and/or adiposity hormone signaling and in the hindbrain and the hypothalamic circuits have been described and are believed to contribute to the pathogenesis of energy imbalance and obesity.
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Affiliation(s)
- Liangyou Rui
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48109-0622, USA,
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31
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Effects of hypocretin and norepinephrine interaction in bed nucleus of the stria terminalis on arterial pressure. Neuroscience 2013; 255:278-91. [PMID: 24070630 DOI: 10.1016/j.neuroscience.2013.09.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 09/16/2013] [Accepted: 09/16/2013] [Indexed: 11/20/2022]
Abstract
Forebrain neuronal circuits containing hypocretin-1 (hcrt-1) and norepinephrine (NE) are important components of central arousal-related processes. Recently, these two systems have been shown to have an overlapping distribution within the bed nucleus of the stria terminalis (BST), a limbic structure activated by stressful challenges, and which functions to adjust arterial pressure (AP) and heart rate (HR) to the stressor. However, whether hcrt-1 and NE interact in BST to alter cardiovascular function is unknown. Experiments were done in urethane-α-chloralose anesthetized, paralyzed, and artificially ventilated male Wistar rats to investigate the effect of hcrt-1 and NE on the cardiovascular responses elicited by l-glutamate (Glu) stimulation of BST neurons. Microinjections of hcrt-1, NE or tyramine into BST attenuated the decrease in AP and HR to Glu stimulation of BST. Additionally, combined injections of hcrt-1 with NE or tyramine did not elicit a greater attenuation than either compound alone. Furthermore, injections into BST of the α2-adrenergic receptor (α2-AR) antagonist yohimbine, but not the α1-AR antagonist 2-{[β-(4-hydroxyphenyl)ethyl]aminomethyl}-1-tetralone hydrochloride, blocked both the hcrt-1 and NE-induced inhibition of the BST cardiovascular depressors responses. Finally, injections into BST of the GABAA receptor antagonist bicuculline, but not the GABAB receptor antagonist phaclofen, blocked the hcrt-1 and NE attenuation of the BST Glu-induced depressor and bradycardia responses. These data suggest that hcrt-1 effects in BST are mediated by NE neurons, and hcrt-1 likely acts to facilitate the synaptic release of NE. NE neurons, acting through α2-AR may activate Gabaergic neurons in BST, which in turn through the activation of GABAA receptors inhibit a BST sympathoinhibitory pathway. Taken together, these data suggest that hcrt-1 pathways to BST through their interaction with NE and Gabaergic neurons may function in the coordination of cardiovascular responses associated with different behavioral states.
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Co-localization of hypocretin-1 and leucine-enkephalin in hypothalamic neurons projecting to the nucleus of the solitary tract and their effect on arterial pressure. Neuroscience 2013; 250:599-613. [PMID: 23912034 DOI: 10.1016/j.neuroscience.2013.07.054] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 07/16/2013] [Accepted: 07/18/2013] [Indexed: 01/03/2023]
Abstract
Experiments were done to investigate whether hypothalamic hypocretin-1 (hcrt-1; orexin-A) neurons that sent axonal projections to cardiovascular responsive sites in the nucleus of the solitary tract (NTS) co-expressed leucine-enkephalin (L-Enk), and to determine the effects of co-administration of hcrt-1 and D-Ala2,D-Leu5-Enkephalin (DADL) into NTS on mean arterial pressure (MAP) and heart rate. In the first series, in the Wistar rat the retrograde tract-tracer fluorogold (FG) was microinjected (50nl) into caudal NTS sites at which L-glutamate (0.25 M; 10 nl) elicited decreases in MAP and where fibers hcrt-1 immunoreactive fibers were observed that also contained L-Enk immunoreactivity. Of the number of hypothalamic hcrt-1 immunoreactive neurons identified ipsilateral to the NTS injection site (1207 ± 78), 32.3 ± 2.3% co-expressed L-Enk immunoreactivity and of these, 2.6 ± 1.1% were retrogradely labeled with FG. Hcrt-1/L-Enk neurons projecting to NTS were found mainly within the perifornical region. In the second series, the region of caudal NTS found to contain axons that co-expressed hcrt-1 and L-Enk immunoreactivity was microinjected with a combination of hcrt-1 and DADL in α-chloralose anesthetized Wistar rats. Microinjection of DADL into NTS elicited depressor and bradycardia responses similar to those elicited by microinjection of hcrt-1. An hcrt-1 injection immediately after the DADL injection elicited an almost twofold increase in the magnitude of the depressor and bradycardia responses compared to those elicited by hcrt-1 alone. Prior injections of the non-specific opioid receptor antagonist naloxone or the specific opioid δ-receptor antagonist ICI 154,129 significantly attenuated the cardiovascular responses to the combined hcrt-1-DADL injections. Taken together, these data suggest that activation of hypothalamic-opioidergic neuronal systems contribute to the NTS hcrt-1 induced cardiovascular responses, and that this descending hypothalamo-medullary pathway may represent the anatomical substrate by which hcrt-1/L-Enk neurons function in the coordination of autonomic-cardiovascular responses during different behavioral states.
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Chase MH. A unified survival theory of the functioning of the hypocretinergic system. J Appl Physiol (1985) 2013; 115:954-71. [PMID: 23640599 DOI: 10.1152/japplphysiol.00700.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
This article advances the theory that the hypocretinergic (orexinergic) system initiates, coordinates, and maintains survival behaviors and survival-related processes (i.e., the Unified Survival Theory of the Functioning of the Hypocretinergic System or "Unified Hypocretinergic Survival Theory"). A priori presumptive support for the Unified Hypocretinergic Survival Theory emanates from the fact that neurons that contain hypocretin are located in the key executive central nervous system (CNS) site, the lateral hypothalamus, that for decades has been well-documented to govern core survival behaviors such as fight, flight, and food consumption. In addition, the hypocretinergic system exhibits the requisite morphological and electrophysiological capabilities to control survival behaviors and related processes. Complementary behavioral data demonstrate that all facets of "survival" are coordinated by the hypocretinergic system and that hypocretinergic directives are not promulgated except during survival behaviors. Importantly, it has been shown that survival behaviors are selectively impacted when the hypocretinergic system is impaired or rendered nonfunctional, whereas other behaviors are relatively unaffected. The Unified Hypocretinergic Survival Theory resolves the disparate, perplexing, and often paradoxical-appearing results of previous studies; it also provides a foundation for future hypothesis-driven basic science and clinical explorations of the hypocretinergic system.
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Affiliation(s)
- Michael H Chase
- WebSciences International, Veterans Affairs-Greater Los Angeles Healthcare System, University of California, Los Angeles School of Medicine, Los Angeles, California
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Grill HJ, Hayes MR. Hindbrain neurons as an essential hub in the neuroanatomically distributed control of energy balance. Cell Metab 2012; 16:296-309. [PMID: 22902836 PMCID: PMC4862653 DOI: 10.1016/j.cmet.2012.06.015] [Citation(s) in RCA: 356] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 03/20/2012] [Accepted: 06/08/2012] [Indexed: 02/07/2023]
Abstract
This Review highlights the processing and integration performed by hindbrain nuclei, focusing on the inputs received by nucleus tractus solitarius (NTS) neurons. These inputs include vagally mediated gastrointestinal satiation signals, blood-borne energy-related hormonal and nutrient signals, and descending neural signals from the forebrain. We propose that NTS (and hindbrain neurons, more broadly) integrate these multiple energy status signals and issue-output commands controlling the behavioral, autonomic, and endocrine responses that collectively govern energy balance. These hindbrain-mediated controls are neuroanatomically distributed; they involve endemic hindbrain neurons and circuits, hindbrain projections to peripheral circuits, and projections to and from midbrain and forebrain nuclei.
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Affiliation(s)
- Harvey J Grill
- Graduate Group of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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