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Coverdell TC, Abbott SBG, Campbell JN. Molecular cell types as functional units of the efferent vagus nerve. Semin Cell Dev Biol 2024; 156:210-218. [PMID: 37507330 PMCID: PMC10811285 DOI: 10.1016/j.semcdb.2023.07.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 07/20/2023] [Accepted: 07/20/2023] [Indexed: 07/30/2023]
Abstract
The vagus nerve vitally connects the brain and body to coordinate digestive, cardiorespiratory, and immune functions. Its efferent neurons, which project their axons from the brainstem to the viscera, are thought to comprise "functional units" - neuron populations dedicated to the control of specific vagal reflexes or organ functions. Previous research indicates that these functional units differ from one another anatomically, neurochemically, and physiologically but have yet to define their identity in an experimentally tractable way. However, recent work with genetic technology and single-cell genomics suggests that genetically distinct subtypes of neurons may be the functional units of the efferent vagus. Here we review how these approaches are revealing the organizational principles of the efferent vagus in unprecedented detail.
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Affiliation(s)
- Tatiana C Coverdell
- Biomedical Sciences Graduate Program, University of Virginia, Charlottesville, VA 22903, USA
| | - Stephen B G Abbott
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22903, USA
| | - John N Campbell
- Department of Biology, University of Virginia, Charlottesville, VA 22903, USA.
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2
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Langhans W, Watts AG, Spector AC. The elusive cephalic phase insulin response: triggers, mechanisms, and functions. Physiol Rev 2023; 103:1423-1485. [PMID: 36422994 PMCID: PMC9942918 DOI: 10.1152/physrev.00025.2022] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 11/04/2022] [Accepted: 11/20/2022] [Indexed: 11/25/2022] Open
Abstract
The cephalic phase insulin response (CPIR) is classically defined as a head receptor-induced early release of insulin during eating that precedes a postabsorptive rise in blood glucose. Here we discuss, first, the various stimuli that elicit the CPIR and the sensory signaling pathways (sensory limb) involved; second, the efferent pathways that control the various endocrine events associated with eating (motor limb); and third, what is known about the central integrative processes linking the sensory and motor limbs. Fourth, in doing so, we identify open questions and problems with respect to the CPIR in general. Specifically, we consider test conditions that allow, or may not allow, the stimulus to reach the potentially relevant taste receptors and to trigger a CPIR. The possible significance of sweetness and palatability as crucial stimulus features and whether conditioning plays a role in the CPIR are also discussed. Moreover, we ponder the utility of the strict classical CPIR definition based on what is known about the effects of vagal motor neuron activation and thereby acetylcholine on the β-cells, together with the difficulties of the accurate assessment of insulin release. Finally, we weigh the evidence of the physiological and clinical relevance of the cephalic contribution to the release of insulin that occurs during and after a meal. These points are critical for the interpretation of the existing data, and they support a sharper focus on the role of head receptors in the overall insulin response to eating rather than relying solely on the classical CPIR definition.
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Affiliation(s)
- Wolfgang Langhans
- Physiology and Behavior Laboratory, ETH Zürich, Schwerzenbach, Switzerland
| | - Alan G Watts
- Department of Biological Sciences, USC Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
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3
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Use of c-peptide as a measure of cephalic phase insulin release in humans. Physiol Behav 2022; 255:113940. [PMID: 35961609 PMCID: PMC9993810 DOI: 10.1016/j.physbeh.2022.113940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 02/08/2023]
Abstract
Cephalic phase insulin release (CPIR) is a rapid pulse of insulin secreted within minutes of food-related sensory stimulation. Understanding the mechanisms underlying CPIR in humans has been hindered by its small observed effect size and high variability within and between studies. One contributing factor to these limitations may be the use of peripherally measured insulin as an indicator of secreted insulin, since a substantial portion of insulin is metabolized by the liver before delivery to peripheral circulation. Here, we investigated the use of c-peptide, which is co-secreted in equimolar amounts to insulin from pancreatic beta cells, as a proxy for insulin secretion during the cephalic phase period. Changes in insulin and c-peptide were monitored in 18 adults over two repeated sessions following oral stimulation with a sucrose-containing gelatin stimulus. We found that, on average, insulin and c-peptide release followed a similar time course over the cephalic phase period, but that c-peptide showed a greater effect size. Importantly, when insulin and c-peptide concentrations were compared across sessions, we found that changes in c-peptide were significantly correlated at the 2 min (r = 0.50, p = 0.03) and 4 min (r = 0.65, p = 0.003) time points, as well as when participants' highest c-peptide concentrations were considered (r = 0.64, p = 0.004). In contrast, no significant correlations were observed for changes in insulin measured from the sessions (r = -0.06-0.35, p > 0.05). Herein, we detail the individual variability of insulin and c-peptide concentrations measured during the cephalic phase period, and identify c-peptide as a valuable metric for insulin secretion alongside insulin concentrations when investigating CPIR.
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Liang SL, Tong YS, Hwang LL, Huang YZ, Chen CY. CART Peptides Differently Regulate Firing Rates and GABAergic Synaptic Inputs of DMV Neurons Innervating the Stomach Antrum and Cecum of Adult Male Rats. Neuroendocrinology 2022; 112:555-570. [PMID: 34348334 DOI: 10.1159/000518690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 07/23/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIM Central administration of cocaine- and amphetamine-regulated transcript peptides (CARTp) alters gastrointestinal motility and reduces food intake in rats. Since neurons in the dorsal motor nucleus of the vagus (DMV) receive GABAergic and glutamatergic inputs and innervate the smooth muscle of gastrointestinal organs, we hypothesized that CARTp acts on the DMV or presynaptic neurons. METHODS We used 3,3'-dioctadecyloxa-carbocyanine perchlorate (DiO) retrograde tracing with electrophysiological methods to record DMV neurons innervating the stomach antrum or cecum in brainstem slices from adult rats. RESULTS DiO application did not change the electrophysiological properties of DMV neurons. CART55-102 had no effect on the basal firing rates of neurons in either the stomach antrum-labeled group (SLG) or cecum-labeled group (CLG). When presynaptic inputs were blocked, CART55-102 further increased the firing rates of the SLG, suggesting a direct excitatory effect. Spontaneous inhibitory postsynaptic currents (sIPSCs) occurred at a higher frequency in SLG neurons than in CLG neurons. CART55-102 reduced the amplitude and the frequency of sIPSCs in SLG neurons dose-dependently, with higher doses also reducing spontaneous excitatory postsynaptic currents (sEPSCs). Higher doses of CART55-102 reduced sIPSC and sEPSC amplitudes in CLG neurons, suggesting a postsynaptic effect. In response to incremental current injections, the SLG neurons exhibited less increases in firing activity. Simultaneous applications of current injections and CART55-102 decreased the firing activity of the CLG. Therefore, stomach antrum-projecting DMV neurons possess a higher gating ability to stabilize firing activity. CONCLUSION The mechanism by which CARTp mediates anorectic actions may be through a direct reduction in cecum-projecting DMV neuron excitability and, to a lesser extent, that of antrum-projecting DMV neurons, by acting on receptors of these neurons.
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Affiliation(s)
- Shu-Ling Liang
- Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan
| | - Yong-Sheng Tong
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ling-Ling Hwang
- Department of Physiology, Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Ying-Zu Huang
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan
- Department of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chih-Yen Chen
- Division of Gastroenterology and Hepatology, Taipei Veterans General Hospital, Faculty of Medicine, Institute of Emergency and Critical Medicine, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
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Cao J, Wang X, Powley TL, Liu Z. Gastric neurons in the nucleus tractus solitarius are selective to the orientation of gastric electrical stimulation. J Neural Eng 2021; 18:10.1088/1741-2552/ac2ec6. [PMID: 34634781 PMCID: PMC8625070 DOI: 10.1088/1741-2552/ac2ec6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/11/2021] [Indexed: 01/02/2023]
Abstract
Objective.Gastric electrical stimulation (GES) is a bioelectric intervention for gastroparesis, obesity, and other functional gastrointestinal disorders. In a potential mechanism of action, GES activates the nerve endings of vagal afferent neurons and induces the vago-vagal reflex through the nucleus tractus solitarius (NTS) in the brainstem. However, it is unclear where and how to stimulate in order to optimize the vagal afferent responses.Approach.To address this question with electrophysiology in rats, we applied mild electrical currents to two serosal targets on the distal forestomach with dense distributions of vagal intramuscular arrays (IMAs) that innervated the circular and longitudinal smooth muscle layers. During stimulation, we recorded single and multi-unit responses from gastric neurons in NTS and evaluated how the recorded responses depended on the stimulus orientation and amplitude.Main results.We found that NTS responses were highly selective to the stimulus orientation for a range of stimulus amplitudes. The strongest responses were observed when the applied current flowed in the same direction as the IMAs in parallel with the underlying smooth muscle fibers. Our results suggest that gastric neurons in NTS may encode the orientation-specific activity of gastric smooth muscles relayed by vagal afferent neurons.Significance.This finding suggests that the orientation of GES is critical to effective engagement of vagal afferents and should be considered in light of the structural phenotypes of vagal terminals in the stomach.
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Affiliation(s)
- Jiayue Cao
- Department of Biomedical Engineering, University of Michigan Ann Arbor
| | - Xiaokai Wang
- Department of Biomedical Engineering, University of Michigan Ann Arbor
| | - Terry L. Powley
- Department of Psychological Sciences, Purdue University West Lafayette
| | - Zhongming Liu
- Department of Biomedical Engineering, University of Michigan Ann Arbor
- Department of Electrical Engineering and Computer Science, University of Michigan Ann Arbor
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Pullicin AJ, Glendinning JI, Lim J. Cephalic phase insulin release: A review of its mechanistic basis and variability in humans. Physiol Behav 2021; 239:113514. [PMID: 34252401 PMCID: PMC8440382 DOI: 10.1016/j.physbeh.2021.113514] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 06/16/2021] [Accepted: 06/30/2021] [Indexed: 12/17/2022]
Abstract
Cephalic phase insulin release (CPIR) is a transient pulse of insulin that occurs within minutes of stimulation from foods or food-related stimuli. Despite decades of research on CPIR in humans, the body of literature surrounding this phenomenon is controversial due in part to contradictory findings . This has slowed progress towards understanding the sensory and neural basis of CPIR, as well as its overall relevance to health. This review examines up-to-date knowledge in CPIR research and identifies sources of CPIR variability in humans in an effort to guide future research. The review starts by defining CPIR and discussing its presumed functional roles in glucose homeostasis and feeding behavior. Next, the types of stimuli that have been reported to elicit CPIR, as well as the sensory and neural mechanisms underlying the response in rodents and humans are discussed, and areas where knowledge is limited are identified. Finally, factors that may contribute to the observed variability of CPIR in humans are examined, including experimental design, test procedure, and individual characteristics. Overall, oral stimulation appears to be important for eliciting CPIR, especially when combined with other sensory modalities (vision, olfaction, somatosensation). While differences in experimental design and testing procedure likely explain some of the observed inter- and intra-study variability, individual differences also appear to play an important role. Understanding sources of these individual differences in CPIR will be key for establishing its health relevance.
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Affiliation(s)
- Alexa J Pullicin
- Department of Food Science & Technology, Oregon State University, Corvallis, OR 97331, USA
| | - John I Glendinning
- Departments of Biology and Neuroscience & Behavior, Barnard College, Columbia University, 3009 Broadway, New York, NY 10027 US
| | - Juyun Lim
- Department of Food Science & Technology, Oregon State University, Corvallis, OR 97331, USA.
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An alternative pathway for sweet sensation: possible mechanisms and physiological relevance. Pflugers Arch 2020; 472:1667-1691. [PMID: 33030576 DOI: 10.1007/s00424-020-02467-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/14/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022]
Abstract
Sweet substances are detected by taste-bud cells upon binding to the sweet-taste receptor, a T1R2/T1R3 heterodimeric G protein-coupled receptor. In addition, experiments with mouse models lacking the sweet-taste receptor or its downstream signaling components led to the proposal of a parallel "alternative pathway" that may serve as metabolic sensor and energy regulator. Indeed, these mice showed residual nerve responses and behavioral attraction to sugars and oligosaccharides but not to artificial sweeteners. In analogy to pancreatic β cells, such alternative mechanism, to sense glucose in sweet-sensitive taste cells, might involve glucose transporters and KATP channels. Their activation may induce depolarization-dependent Ca2+ signals and release of GLP-1, which binds to its receptors on intragemmal nerve fibers. Via unknown neuronal and/or endocrine mechanisms, this pathway may contribute to both, behavioral attraction and/or induction of cephalic-phase insulin release upon oral sweet stimulation. Here, we critically review the evidence for a parallel sweet-sensitive pathway, involved signaling mechanisms, neural processing, interactions with endocrine hormonal mechanisms, and its sensitivity to different stimuli. Finally, we propose its physiological role in detecting the energy content of food and preparing for digestion.
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Lasschuijt MP, Mars M, de Graaf C, Smeets PAM. Endocrine Cephalic Phase Responses to Food Cues: A Systematic Review. Adv Nutr 2020; 11:1364-1383. [PMID: 32516803 PMCID: PMC7490153 DOI: 10.1093/advances/nmaa059] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 01/10/2020] [Accepted: 04/29/2020] [Indexed: 01/16/2023] Open
Abstract
Cephalic phase responses (CPRs) are conditioned anticipatory physiological responses to food cues. They occur before nutrient absorption and are hypothesized to be important for satiation and glucose homeostasis. Cephalic phase insulin responses (CPIRs) and pancreatic polypeptide responses (CPPPRs) are found consistently in animals, but human literature is inconclusive. We performed a systematic review of human studies to determine the magnitude and onset time of these CPRs. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to develop a search strategy. The terms included in the search strategy were cephalic or hormone response or endocrine response combined with insulin and pancreatic polypeptide (PP). The following databases were searched: Scopus (Elsevier), Science Direct, PubMed, Google Scholar, and The Cochrane Library. Initially, 582 original research articles were found, 50 were included for analysis. An insulin increase (≥1μIU/mL) was observed in 41% of the treatments (total n = 119). In 22% of all treatments the increase was significant from baseline. The median (IQR) insulin increase was 2.5 (1.6-4.5) μIU/mL, 30% above baseline at 5± 3 min after food cue onset (based on study treatments that induced ≥1 μIU/mL insulin increase). A PP increase (>10 pg/mL) was found in 48% of the treatments (total n = 42). In 21% of the treatments, the increase was significant from baseline. The median (IQR) PP increase was 99 (26-156) pg/mL, 68% above baseline at 9± 4 min after food cue onset (based on study treatments that induced ≥1 μIU/mL insulin increase). In conclusion, CPIRs are small compared with spontaneous fluctuations. Although CPPPRs are of a larger magnitude, both show substantial variation in magnitude and onset time. We found little evidence for CPIR or CPPPR affecting functional outcomes, that is, satiation and glucose homeostasis. Therefore, CPRs do not seem to be biologically meaningful in daily life.
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Affiliation(s)
- Marlou P Lasschuijt
- Division of Human Nutrition and Health, Wageningen University & Research, Wageningen, The Netherlands
| | - Monica Mars
- Division of Human Nutrition and Health, Wageningen University & Research, Wageningen, The Netherlands
| | - Cees de Graaf
- Division of Human Nutrition and Health, Wageningen University & Research, Wageningen, The Netherlands
| | - Paul A M Smeets
- Division of Human Nutrition and Health, Wageningen University & Research, Wageningen, The Netherlands
- Image Sciences Institute, University Medical Center Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
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Oketa‐Onyut Julu P. Normal autonomic neurophysiology of postural orthostatic tachycardia and recommended physiological assessments in postural orthostatic tachycardia syndrome. Physiol Rep 2020; 8:e14465. [PMID: 32588974 PMCID: PMC7318787 DOI: 10.14814/phy2.14465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 05/03/2020] [Accepted: 05/04/2020] [Indexed: 11/24/2022] Open
Abstract
The current surge of interest in postural orthostatic tachycardia syndrome commonly known as POTS requires good knowledge of the very complex physiology involved, but this is currently lacking. The often overlooked normal physiology of orthostasis is reviewed including the definition of normal postural orthostatic tachycardia. An illustrated functional anatomy that embeds orthostatic tachycardia within the learned and skilful motor functions in the human population is presented. The four physiological phases of orthostasis and the role of tachycardia are described in a laboratory-controlled and progressive orthostatic stress in normal human volunteers. Standardized surrogate measures of autonomic control were used to quantify the trigger level for excessive tachycardia and the minimum autonomic control required to sustain viable arterial blood pressure during severe orthostatic stress in normal human volunteers. Tachycardia during orthostasis is part of a "democratic" contribution by four cardiovascular parameters of which the chronotropic function of the heart is just one of the parameters contributing toward cardiovascular compensation. It is adjusted during orthostasis in proportion to contributions from the other three parameters, namely inotropic function of the heart, windkessel vascular resistance and venous vascular capacitance. The physiological effects of the two stressors during orthostasis, gravity and isometric contraction of skeletal muscles are reviewed. A model of how the four cardiovascular parameters are regulated during orthostasis to achieve proportionate contributions is proposed emphasizing the necessity to quantify individual contributions from all these four parameters. Any one or more of these parameters may be compromised due to disease requiring disproportionate contribution of the prevailing magnitude of orthostatic tachycardia in an individual. It therefore requires neurophysiological assessment of the autonomic regulation of all the four cardiovascular parameters to assess the condition fully. We recommend here some current and novel neurophysiological methods that use modern medical technology to quantify laboratory standardized surrogate measures of some of these cardiovascular parameters including central parasympathetic regulation in postural orthostatic tachycardia syndrome.
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Affiliation(s)
- Peter Oketa‐Onyut Julu
- Clinical Research CentreWilliam Harvey Heart CentreBarts and the London School of Medicine and DentistryCharterhouse SquareLondonUK
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Gastrin releasing peptide-induced satiety is associated with hypothalamic and brainstem changes in chicks. Neurosci Lett 2019; 713:134529. [PMID: 31585210 DOI: 10.1016/j.neulet.2019.134529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/24/2019] [Accepted: 09/30/2019] [Indexed: 11/23/2022]
Abstract
Gastrin releasing peptide (GRP) is involved in the stimulation of gastric acid release from the stomach. It also mediates effects on feeding behavior. It is associated with anorexigenic effects in both mammalian and avian species, but the mechanism of action is unknown in any species. The aim of the present study was thus to investigate the hypothalamic and brainstem mechanisms mediating GRP-induced satiety in chicks. In Experiment 1, chicks that received intracerebroventricular (ICV) injection of GRP reduced food intake for up to 150 min following injection and reduced water intake up to 120 min following injection. In Experiment 2, chicks that were food restricted following GRP injection did not reduce water intake. Alimentary canal transit time was not affected by GRP in Experiment 3. A behavior analysis was conducted in Experiment 4, revealing that GRP-treated chicks reduced feeding pecks. In Experiment 5, GRP-treated chicks had increased c-Fos immunoreactivity in the lateral hypothalamus, paraventricular nucleus, and arcuate nucleus of the hypothalamus, and the nucleus of the solitary tract. Collectively, these results demonstrate that central GRP causes anorexigenic effects that are associated with hypothalamic changes without affecting other behaviors.
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Ichiki T, Augustine V, Oka Y. Neural populations for maintaining body fluid balance. Curr Opin Neurobiol 2019; 57:134-140. [PMID: 30836260 PMCID: PMC7006364 DOI: 10.1016/j.conb.2019.01.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 01/14/2019] [Indexed: 01/03/2023]
Abstract
Fine balance between loss-of water and gain-of water is essential for maintaining body fluid homeostasis. The development of neural manipulation and mapping tools has opened up new avenues to dissect the neural circuits underlying body fluid regulation. Recent studies have identified several nodes in the brain that positively and negatively regulate thirst. The next step forward would be to elucidate how neural populations interact with each other to control drinking behavior.
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Affiliation(s)
- Takako Ichiki
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd Mail Code: 216-76, Pasadena, CA 91125, USA
| | - Vineet Augustine
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd Mail Code: 216-76, Pasadena, CA 91125, USA
| | - Yuki Oka
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd Mail Code: 216-76, Pasadena, CA 91125, USA.
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Suarez AN, Noble EE, Kanoski SE. Regulation of Memory Function by Feeding-Relevant Biological Systems: Following the Breadcrumbs to the Hippocampus. Front Mol Neurosci 2019; 12:101. [PMID: 31057368 PMCID: PMC6482164 DOI: 10.3389/fnmol.2019.00101] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/03/2019] [Indexed: 12/15/2022] Open
Abstract
The hippocampus (HPC) controls fundamental learning and memory processes, including memory for visuospatial navigation (spatial memory) and flexible memory for facts and autobiographical events (declarative memory). Emerging evidence reveals that hippocampal-dependent memory function is regulated by various peripheral biological systems that are traditionally known for their roles in appetite and body weight regulation. Here, we argue that these effects are consistent with a framework that it is evolutionarily advantageous to encode and recall critical features surrounding feeding behavior, including the spatial location of a food source, social factors, post-absorptive processing, and other episodic elements of a meal. We review evidence that gut-to-brain communication from the vagus nerve and from feeding-relevant endocrine systems, including ghrelin, insulin, leptin, and glucagon-like peptide-1 (GLP-1), promote hippocampal-dependent spatial and declarative memory via neurotrophic and neurogenic mechanisms. The collective literature reviewed herein supports a model in which various stages of feeding behavior and hippocampal-dependent memory function are closely linked.
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Affiliation(s)
| | | | - Scott E. Kanoski
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
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13
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Rauch HGL, Hume DJ, Howells FM, Kroff J, Lambert EV. Food Cue Reactivity and the Brain-Heart Axis During Cognitive Stress Following Clinically Relevant Weight Loss. Front Nutr 2019; 5:135. [PMID: 30662897 PMCID: PMC6328490 DOI: 10.3389/fnut.2018.00135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 12/11/2018] [Indexed: 12/05/2022] Open
Abstract
Successful weight loss maintainers are more vulnerable to stress induced eating. The aim of our study was to determine what effect an attention-demanding cognitive performance task had on brain-heart reactivity to visual food cues in women who maintained clinically relevant weight loss vs. women who had never weight cycled. A clinical weight loss group (CWL, n = 17) and a BMI-matched control group (CTL, n = 23) completed modified Stroop tasks that either included high calorie food pictures (Food Stroop) or excluded food cues (Office Stroop). ECG, breathing rate, and EEG were recorded. CWL participants: The Eating Restraint scores (Three Factor Eating Questionnaire) of the CWL participants correlated negatively with their heart rates recorded during the Food Stroop task (r = 0.62, p < 0.01). There was no such relationship in CTL participants. The P200 latencies in CWL participants evoked by the Stroop color-word cues at the C3 electrode were positively correlated to the log high frequency power in their cardiac spectrograms during the Food Stroop (r = 0.63, p < 0.02). There were no such relationships in the Office Stroop task nor in CTL participants. Combined Groups: Participants' heart rates were significantly lower (p < 0.05) and their RMSSD values and the log Total Power in their cardiac spectrograms were significantly greater during the Food Stroop vs. Office Stroop (p < 0.01, Bonferroni corrected). In conclusion Eating Restraint scores in CWL participants correlated with their Stroop heart rates, while the P200 latencies evoked by the Stroop cues correlated with the log high frequency power in their cardiac spectrograms (marker of cardiac vagal activation) during the Food Stroop task. This provides evidence that even 12 months after successful weight loss maintenance the cardiac ANS reactivity to food cues while completing a cognitive performance test was still different to that in individuals of normal weight who never weight cycled. Across all participants the cardiac ANS reactivity evoked by performing the Stroop task was lowered by food cues suggesting that the dampening effect of food cues on cardiac ANS reactivity may be one of the drivers of ‘stress induced' eating.
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Affiliation(s)
- Henri G Laurie Rauch
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - David J Hume
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Fleur M Howells
- Department of Psychiatry and Mental Health, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Jacolene Kroff
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Estelle Victoria Lambert
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Rationalization of the Irrational Neuropathologic Basis of Hypothyroidism-Olfaction Disorders Paradox: Experimental Study. World Neurosurg 2017; 107:400-408. [DOI: 10.1016/j.wneu.2017.07.180] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 07/26/2017] [Accepted: 07/29/2017] [Indexed: 01/04/2023]
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Blasi C. The Role of the Vagal Nucleus Tractus Solitarius in the Therapeutic Effects of Obesity Surgery and Other Interventional Therapies on Type 2 Diabetes. Obes Surg 2016; 26:3045-3057. [DOI: 10.1007/s11695-016-2419-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Gourine AV, Machhada A, Trapp S, Spyer KM. Cardiac vagal preganglionic neurones: An update. Auton Neurosci 2016; 199:24-8. [DOI: 10.1016/j.autneu.2016.06.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/17/2016] [Indexed: 01/06/2023]
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17
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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: 5.1] [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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18
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Röder PV, Wu B, Liu Y, Han W. Pancreatic regulation of glucose homeostasis. Exp Mol Med 2016; 48:e219. [PMID: 26964835 PMCID: PMC4892884 DOI: 10.1038/emm.2016.6] [Citation(s) in RCA: 467] [Impact Index Per Article: 58.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 12/03/2015] [Accepted: 12/06/2015] [Indexed: 12/11/2022] Open
Abstract
In order to ensure normal body function, the human body is dependent on a tight control of its blood glucose levels. This is accomplished by a highly sophisticated network of various hormones and neuropeptides released mainly from the brain, pancreas, liver, intestine as well as adipose and muscle tissue. Within this network, the pancreas represents a key player by secreting the blood sugar-lowering hormone insulin and its opponent glucagon. However, disturbances in the interplay of the hormones and peptides involved may lead to metabolic disorders such as type 2 diabetes mellitus (T2DM) whose prevalence, comorbidities and medical costs take on a dramatic scale. Therefore, it is of utmost importance to uncover and understand the mechanisms underlying the various interactions to improve existing anti-diabetic therapies and drugs on the one hand and to develop new therapeutic approaches on the other. This review summarizes the interplay of the pancreas with various other organs and tissues that maintain glucose homeostasis. Furthermore, anti-diabetic drugs and their impact on signaling pathways underlying the network will be discussed.
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Affiliation(s)
- Pia V Röder
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore. E-mail: or
| | - Bingbing Wu
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore
| | - Yixian Liu
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore
| | - Weiping Han
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore. E-mail: or
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Browning KN, Travagli RA. Central nervous system control of gastrointestinal motility and secretion and modulation of gastrointestinal functions. Compr Physiol 2015; 4:1339-68. [PMID: 25428846 DOI: 10.1002/cphy.c130055] [Citation(s) in RCA: 322] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Although the gastrointestinal (GI) tract possesses intrinsic neural plexuses that allow a significant degree of autonomy over GI functions, the central nervous system (CNS) provides extrinsic neural inputs that regulate, modulate, and control these functions. While the intestines are capable of functioning in the absence of extrinsic inputs, the stomach and esophagus are much more dependent upon extrinsic neural inputs, particularly from parasympathetic and sympathetic pathways. The sympathetic nervous system exerts a predominantly inhibitory effect upon GI muscle and provides a tonic inhibitory influence over mucosal secretion while, at the same time, regulates GI blood flow via neurally mediated vasoconstriction. The parasympathetic nervous system, in contrast, exerts both excitatory and inhibitory control over gastric and intestinal tone and motility. Although GI functions are controlled by the autonomic nervous system and occur, by and large, independently of conscious perception, it is clear that the higher CNS centers influence homeostatic control as well as cognitive and behavioral functions. This review will describe the basic neural circuitry of extrinsic inputs to the GI tract as well as the major CNS nuclei that innervate and modulate the activity of these pathways. The role of CNS-centered reflexes in the regulation of GI functions will be discussed as will modulation of these reflexes under both physiological and pathophysiological conditions. Finally, future directions within the field will be discussed in terms of important questions that remain to be resolved and advances in technology that may help provide these answers.
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Affiliation(s)
- Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania
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20
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Glendinning JI, Stano S, Holter M, Azenkot T, Goldman O, Margolskee RF, Vasselli JR, Sclafani A. Sugar-induced cephalic-phase insulin release is mediated by a T1r2+T1r3-independent taste transduction pathway in mice. Am J Physiol Regul Integr Comp Physiol 2015; 309:R552-60. [PMID: 26157055 PMCID: PMC4591378 DOI: 10.1152/ajpregu.00056.2015] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 07/06/2015] [Indexed: 12/11/2022]
Abstract
Sensory stimulation from foods elicits cephalic phase responses, which facilitate digestion and nutrient assimilation. One such response, cephalic-phase insulin release (CPIR), enhances glucose tolerance. Little is known about the chemosensory mechanisms that activate CPIR. We studied the contribution of the sweet taste receptor (T1r2+T1r3) to sugar-induced CPIR in C57BL/6 (B6) and T1r3 knockout (KO) mice. First, we measured insulin release and glucose tolerance following oral (i.e., normal ingestion) or intragastric (IG) administration of 2.8 M glucose. Both groups of mice exhibited a CPIR following oral but not IG administration, and this CPIR improved glucose tolerance. Second, we examined the specificity of CPIR. Both mouse groups exhibited a CPIR following oral administration of 1 M glucose and 1 M sucrose but not 1 M fructose or water alone. Third, we studied behavioral attraction to the same three sugar solutions in short-term acceptability tests. B6 mice licked more avidly for the sugar solutions than for water, whereas T1r3 KO mice licked no more for the sugar solutions than for water. Finally, we examined chorda tympani (CT) nerve responses to each of the sugars. Both mouse groups exhibited CT nerve responses to the sugars, although those of B6 mice were stronger. We propose that mice possess two taste transduction pathways for sugars. One mediates behavioral attraction to sugars and requires an intact T1r2+T1r3. The other mediates CPIR but does not require an intact T1r2+T1r3. If the latter taste transduction pathway exists in humans, it should provide opportunities for the development of new treatments for controlling blood sugar.
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Affiliation(s)
- John I Glendinning
- Department of Biology, Barnard College, Columbia University, New York, New York;
| | - Sarah Stano
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Marlena Holter
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Tali Azenkot
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Olivia Goldman
- Department of Biology, Barnard College, Columbia University, New York, New York
| | | | - Joseph R Vasselli
- Obesity Research Center, Department of Medicine, Columbia University, New York, New York; and
| | - Anthony Sclafani
- Department of Psychology, Brooklyn College of City University of New York, Brooklyn, New York
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Abstract
We review our recent behavioural and imaging studies testing the consequences of congenital blindness on the chemical senses in comparison with the condition of anosmia. We found that congenitally blind (CB) subjects have increased sensitivity for orthonasal odorants and recruit their visually deprived occipital cortex to process orthonasal olfactory stimuli. In sharp contrast, CB perform less well than sighted controls in taste and retronasal olfaction, i.e. when processing chemicals inside the mouth. Interestingly, CB do not recruit their occipital cortex to process taste stimuli. In contrast to these findings in blindness, congenital anosmia is associated with lower taste and trigeminal sensitivity, accompanied by weaker activations within the 'flavour network' upon exposure to such stimuli. We conclude that functional adaptations to congenital anosmia or blindness are quite distinct, such that CB can train their exteroceptive chemical senses and recruit normally visual cortical areas to process chemical information from the surrounding environment.
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Neural correlates of taste perception in congenital blindness. Neuropsychologia 2015; 70:227-34. [PMID: 25708174 DOI: 10.1016/j.neuropsychologia.2015.02.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 02/13/2015] [Accepted: 02/19/2015] [Indexed: 11/22/2022]
Abstract
Sight is undoubtedly important for the perception and the assessment of the palatability of tastants. Although many studies have addressed the consequences of visual impairment on food selection, feeding behavior, eating habits and taste perception, nothing is known about the neural correlates of gustation in blindness. In the current study we examined brain responses during gustation using functional magnetic resonance imaging (fMRI). We scanned nine congenitally blind and 14 age- and sex-matched blindfolded sighted control subjects, matched in age, gender and body mass index (BMI), while they made judgments of either the intensity or the (un)pleasantness of different tastes (sweet, bitter) or artificial saliva that were delivered intra-orally. The fMRI data indicated that during gustation, congenitally blind individuals activate less strongly the primary taste cortex (right posterior insula and overlying Rolandic operculum) and the hypothalamus. In sharp contrast with results of multiple other sensory processing studies in congenitally blind subjects, including touch, audition and smell, the occipital cortex was not recruited during taste processing, suggesting the absence of taste-related compensatory crossmodal responses in the occipital cortex. These results underscore our earlier behavioral demonstration that congenitally blind subjects have a lower gustatory sensitivity compared to normal sighted individuals. We hypothesize that due to an underexposure to a variety of tastants, training-induced crossmodal sensory plasticity to gustatory stimulation does not occur in blind subjects.
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The multifactorial interplay of diet, the microbiome and appetite control: current knowledge and future challenges. Proc Nutr Soc 2015; 74:235-44. [DOI: 10.1017/s0029665114001670] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The recent availability of high-throughput nucleic acid sequencing technologies has rapidly advanced approaches to analysing the role of the gut microbiome in governance of human health, including gut health, and also metabolic, cardiovascular and mental health,inter alia. Recent scientific studies suggest that energy intake (EI) perturbations at the population level cannot account for the current obesity epidemic, and significant work is investigating the potential role of the microbiome, and in particular its metabolic products, notably SCFA, predominantly acetate, propionate and butyrate, the last of which is an energy source for the epithelium of the large intestine. The energy yield from dietary residues may be a significant factor influencing energy balance. This review posits that the contribution towards EI is governed by EI diet composition (not just fibre), the composition of the microbiome and by the levels of physical activity. Furthermore, we hypothesise that these factors do not exist in a steady state, but rather are dynamic, with both short- and medium-term effects on appetite regulation. We suggest that the existing modelling strategies for bacterial dynamics, specifically for growth in chemostat culture, are of utility in understanding the dynamic interplay of diet, activity and microbiomic organisation. Such approaches may be informative in optimising the application of dietary and microbial therapy to promote health.
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24
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Nasse JS. A novel slice preparation to study medullary oromotor and autonomic circuits in vitro. J Neurosci Methods 2014; 237:41-53. [PMID: 25196216 DOI: 10.1016/j.jneumeth.2014.08.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/22/2014] [Accepted: 08/24/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND The medulla is capable of controlling and modulating ingestive behavior and gastrointestinal function. These two functions, which are critical to maintaining homeostasis, are governed by an interconnected group of nuclei dispersed throughout the medulla. As such, in vitro experiments to study the neurophysiologic details of these connections have been limited by spatial constraints of conventional slice preparations. NEW METHOD This study demonstrates a novel method of sectioning the medulla so that sensory, integrative, and motor nuclei that innervate the gastrointestinal tract and the oral cavity remain intact. RESULTS Immunohistochemical staining against choline-acetyl-transferase and dopamine-β-hydroxylase demonstrated that within a 450 μm block of tissue we are able to capture sensory, integrative and motor nuclei that are critical to oromotor and gastrointestinal function. Within slice tracing shows that axonal projections from the NST to the reticular formation and from the reticular formation to the hypoglossal motor nucleus (mXII) persist. Live-cell calcium imaging of the slice demonstrates that stimulation of either the rostral or caudal NST activates neurons throughout the NST, as well as the reticular formation and mXII. COMPARISON WITH EXISTING METHODS This new method of sectioning captures a majority of the nuclei that are active when ingesting a meal. Tradition planes of section, i.e. coronal, horizontal or sagittal, contain only a limited portion of the substrate. CONCLUSIONS Our results demonstrate that both anatomical and physiologic connections of oral and visceral sensory nuclei that project to integrative and motor nuclei remain intact with this new plane of section.
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Affiliation(s)
- Jason S Nasse
- Division of Biosciences, College of Dentistry, 305 West 12th Avenue, 4154 Postle Hall, The Ohio State University, Columbus, OH 43210, United States.
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25
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Schneider JE, Wise JD, Benton NA, Brozek JM, Keen-Rhinehart E. When do we eat? Ingestive behavior, survival, and reproductive success. Horm Behav 2013; 64:702-28. [PMID: 23911282 DOI: 10.1016/j.yhbeh.2013.07.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 07/21/2013] [Accepted: 07/22/2013] [Indexed: 12/13/2022]
Abstract
The neuroendocrinology of ingestive behavior is a topic central to human health, particularly in light of the prevalence of obesity, eating disorders, and diabetes. The study of food intake in laboratory rats and mice has yielded some useful hypotheses, but there are still many gaps in our knowledge. Ingestive behavior is more complex than the consummatory act of eating, and decisions about when and how much to eat usually take place in the context of potential mating partners, competitors, predators, and environmental fluctuations that are not present in the laboratory. We emphasize appetitive behaviors, actions that bring animals in contact with a goal object, precede consummatory behaviors, and provide a window into motivation. Appetitive ingestive behaviors are under the control of neural circuits and neuropeptide systems that control appetitive sex behaviors and differ from those that control consummatory ingestive behaviors. Decreases in the availability of oxidizable metabolic fuels enhance the stimulatory effects of peripheral hormones on appetitive ingestive behavior and the inhibitory effects on appetitive sex behavior, putting a new twist on the notion of leptin, insulin, and ghrelin "resistance." The ratio of hormone concentrations to the availability of oxidizable metabolic fuels may generate a critical signal that schedules conflicting behaviors, e.g., mate searching vs. foraging, food hoarding vs. courtship, and fat accumulation vs. parental care. In species representing every vertebrate taxa and even in some invertebrates, many putative "satiety" or "hunger" hormones function to schedule ingestive behavior in order to optimize reproductive success in environments where energy availability fluctuates.
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Affiliation(s)
- Jill E Schneider
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Bethlehem, PA 18015, USA
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Abstract
There is now abundant functional and anatomical evidence that autonomic motor pathways represent a highly organized output of the central nervous system. Simplistic notions of antagonistic all-or-none activation of sympathetic or parasympathetic pathways are clearly wrong. Sympathetic or parasympathetic pathways to specific target tissues generally can be activated tonically or phasically, depending on current physiological requirements. For example, at rest, many sympathetic pathways are tonically active, such as those limiting blood flow to the skin, inhibiting gastrointestinal tract motility and secretion, or allowing continence in the urinary bladder. Phasic parasympathetic activity can be seen in lacrimation, salivation or urination. Activity in autonomic motor pathways can be modulated by diverse sensory inputs, including the visual, auditory and vestibular systems, in addition to various functional populations of visceral afferents. Identifying the central pathways responsible for coordinated autonomic activity has made considerable progress, but much more needs to be done.
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Affiliation(s)
- Ian Gibbins
- Anatomy & Histology; Flinders University; SA Austraila
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27
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Gagnon L, Kupers R, Ptito M. Reduced Taste Sensitivity in Congenital Blindness. Chem Senses 2013; 38:509-17. [DOI: 10.1093/chemse/bjt021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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28
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Gorden A, Yang R, Yerges-Armstrong LM, Ryan KA, Speliotes E, Borecki IB, Harris TB, Chu X, Wood GC, Still CD, Shuldiner AR, Gerhard GS. Genetic variation at NCAN locus is associated with inflammation and fibrosis in non-alcoholic fatty liver disease in morbid obesity. Hum Hered 2013; 75:34-43. [PMID: 23594525 DOI: 10.1159/000346195] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 11/27/2012] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVE Obesity-associated non-alcoholic fatty liver disease (NAFLD) may cause liver dysfunction and failure. In a previously reported genome-wide association meta-analysis, single nucleotide polymorphisms (SNPs) near PNPLA3, NCAN, GCKR, LYPLAL1 and PPP1R3B were associated with NAFLD and with distinctive serum lipid profiles. The present study examined the relevance of these variants to NAFLD in extreme obesity. METHODS In 1,092 bariatric surgery patients, the candidate SNPs were genotyped and association analyses with liver histology and serum lipids were performed. RESULTS We replicated the association of hepatosteatosis with PNPLA3 rs738409[G] and with NCAN rs2228603[T]. We also replicated the association of rs2228603[T] with hepatic inflammation and fibrosis. rs2228603[T] was associated with lower serum low-density lipoprotein, total cholesterol and triglycerides. After stratification by the presence or absence of NAFLD, these associations were present predominantly in the subgroup with NAFLD. CONCLUSION NCAN rs2228603[T] is a risk factor for liver inflammation and fibrosis, suggesting that this locus is responsible for progression from steatosis to steatohepatitis. In this bariatric cohort, rs2228603[T] was associated with low serum lipids only in patients with NAFLD. This supports a NAFLD model in which the liver may sequester triglycerides as a result of either increased triglyceride uptake and/or decreased lipolysis.
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Affiliation(s)
- Alexis Gorden
- Division of Gastroenterology, University of Maryland School of Medicine, Baltimore, MD, USA
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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: 323] [Impact Index Per Article: 26.9] [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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30
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Autonomic Nervous System In Vitro: Studying Tonically Active Neurons Controlling Vagal Outflow in Rodent Brainstem Slices. ISOLATED CENTRAL NERVOUS SYSTEM CIRCUITS 2012. [DOI: 10.1007/978-1-62703-020-5_1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Effect of dental status on changes in mastication in patients with obesity following bariatric surgery. PLoS One 2011; 6:e22324. [PMID: 21799822 PMCID: PMC3140511 DOI: 10.1371/journal.pone.0022324] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 06/25/2011] [Indexed: 11/20/2022] Open
Abstract
Background Patients scheduled for bariatric surgery (BS) are encouraged to chew slowly in order to optimise the digestion process. The influence of dental status on patients' ability to comply with advice on chewing behaviour is poorly documented. This study aims to compare modifications of chewing function before and after BS in three groups of obese patients differing in dental status. Method and Findings A cohort of 46 obese women provided three groups: FD group: fully dentate (7–10 functional dental units [FU]); PD group: partially dentate (4–6 FU) without partial dentures; DW group: partial and complete denture wearers. Chewing time (CT), number of chewing cycles (CC), and chewing frequency (CF) were measured before and after surgery during mastication of standardised samples of raw carrot, peanuts, banana, apple and jelly. The median particle-size distribution (D50) of the pre-swallowed bolus was also evaluated for peanut and carrot. Before surgery, the PD and DW groups exhibited greater mean CCs and CTs than the FD group (SNK p<0.05) and produced a bolus with higher granulometry (SNK, p<0.05) than the FD group. After surgery, CT and CC increased for all groups and for all foods, but not statistically significant for jelly. The resulting changes in bolus granulometry observed depended on both food and dental status. The granulometry of carrot bolus remained as fine or as coarse in FD and DW groups respectively as it was before surgery while it was significantly decreased in the PD group (Student's test, p<0.001). Conclusions After bariatric surgery, all the obese patients, regardless of dental status modified their chewing kinematics. The effects of this chewing behaviour on bolus granulometry depended on dental status and type of food. Further studies are needed to understand better the impact of dental status on feeding behaviour and nutrition in patients with obesity.
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32
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Vahl TP, Drazen DL, Seeley RJ, D'Alessio DA, Woods SC. Meal-anticipatory glucagon-like peptide-1 secretion in rats. Endocrinology 2010; 151:569-75. [PMID: 19915164 PMCID: PMC2817629 DOI: 10.1210/en.2009-1002] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Animals anticipating a meal initiate a series of responses enabling them to better cope with the meal's metabolic impact. These responses, such as cephalic insulin, occur prior to the onset of ingestion and are especially evident in animals maintained on a meal-feeding schedule with limited but predictable access to food each day. We tested the hypothesis that meal-fed rats secrete the incretin hormone glucagon-like peptide-1 (GLP-1) cephalically when anticipating a large meal. Male Long-Evans rats were fed ad libitum (controls) or adapted to a schedule on which food was available for the same 4-h period each day (meal fed animals). Plasma GLP-1 increased in meal-fed rats over an interval from 75 to 60 min prior to feeding time, from a baseline of 10 to around 40 pm, and then returned to baseline prior to food presentation. Controls had steady plasma GLP-1 levels (10-15 pm) over the same span. Meal-fed rats also secreted cephalic insulin starting around 15 min prior to food presentation. Administration of the selective GLP-1 receptor antagonist exendin-4[desHis-1,Glu-9] prior to the premeal spike of GLP-1 caused meal-fed rats to eat significantly less food than normal, whereas administration of the antagonist after the GLP-1 spike but prior to food presentation resulted in a significant increase in food consumption. These findings document for the first time a cephalic increase of plasma GLP-1 and suggest that it functions to facilitate consumption of a large meal.
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Affiliation(s)
- Torsten P Vahl
- Department of Psychiatry, University of Cincinnati, 2170 East Galbraith Road, Cincinnati, Ohio 45237, USA
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33
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Affiliation(s)
- Diana L Williams
- Department of Psychology, B328, PDB, 1107 West Call Street, Florida State University, Tallahassee, Florida 32306-4301, USA.
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34
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Grill HJ. Leptin and the systems neuroscience of meal size control. Front Neuroendocrinol 2010; 31:61-78. [PMID: 19836413 PMCID: PMC2813996 DOI: 10.1016/j.yfrne.2009.10.005] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 10/12/2009] [Accepted: 10/13/2009] [Indexed: 12/14/2022]
Abstract
The development of effective pharmacotherapy for obesity will benefit from a more complete understanding of the neural pathways and the neurochemical signals whose actions result in the reduction of the size of meals. This review examines the neural control of meal size and the integration of two principal sources of that control--satiation signals arising from the gastrointestinal tract and CNS leptin signaling. Four types of integrations that are central to the control of meal size are described and each involves the neurons of the nucleus tractus solitarius (NTS) in the dorsal hindbrain. Data discussed show that NTS neurons integrate information arising from: (1) ascending GI-derived vagal afferent projections, (2) descending neuropeptidergic projections from leptin-activated arcuate and paraventricular nucleus neurons, (3) leptin signaling in NTS neurons themselves and (4) melanocortinergic projections from NTS and hypothalamic POMC neurons to NTS neurons and melanocortinergic modulation of vagal afferent nerve terminals that are presynaptic to NTS neurons.
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Affiliation(s)
- Harvey J Grill
- Graduate Groups of Psychology and Neuroscience, University of Pennsylvania, 3720 Walnut Street, Philadelphia, PA 19104, USA
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35
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Ikenaga T, Ogura T, Finger TE. Vagal gustatory reflex circuits for intraoral food sorting behavior in the goldfish: cellular organization and neurotransmitters. J Comp Neurol 2009; 516:213-25. [PMID: 19598285 DOI: 10.1002/cne.22097] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The sense of taste is crucial in an animal's determination as to what is edible and what is not. This gustatory function is especially important in goldfish, who utilize a sophisticated oropharyngeal sorting mechanism to separate food from substrate material. The computational aspects of this detection are carried out by the medullary vagal lobe, which is a large, laminated structure combining elements of both the gustatory nucleus of the solitary tract and the nucleus ambiguus. The sensory layers of the vagal lobe are coupled to the motor layers via a simple reflex arc. Details of this reflex circuit were investigated with histology and calcium imaging. Biocytin injections into the motor layer labeled vagal reflex interneurons that have radially directed dendrites ramifying within the layers of primary afferent terminals. Axons of reflex interneurons extend radially inward to terminate onto both vagal motoneurons and small, GABAergic interneurons in the motor layer. Functional imaging shows increases in intracellular Ca++ of vagal motoneurons following electrical stimulation in the sensory layer. These responses were suppressed under Ca(++)-free conditions and by interruption of the axons bridging between the sensory and motor layers. Pharmacological experiments showed that glutamate acting via (+/-)-alpha-amino-3-hydroxy- 5-ethylisoxazole-4-propioinc acid (AMPA)/kainate and N-methyl-D-aspartic acid (NMDA) receptors mediate neurotransmission between reflex interneurons and vagal motoneurons. Thus, the vagal gustatory portion of the viscerosensory complex is linked to branchiomotor neurons of the pharynx via a glutamatergic interneuronal system.
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Affiliation(s)
- Takanori Ikenaga
- Rocky Mountain Taste & Smell Center, Department of Cell and Developmental Biology, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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Hayes MR, Skibicka KP, Bence KK, Grill HJ. Dorsal hindbrain 5'-adenosine monophosphate-activated protein kinase as an intracellular mediator of energy balance. Endocrinology 2009; 150:2175-82. [PMID: 19116341 PMCID: PMC2671900 DOI: 10.1210/en.2008-1319] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The fuel-sensing enzyme AMP-activated protein kinase (AMPK) has been implicated in central nervous system control of energy balance. Hypothalamic AMPK activity is increased by food deprivation, and this elevation is inhibited by refeeding or by leptin treatment. The contribution of extrahypothalamic AMPK activity in energy balance control has not been addressed. Here, we investigate the effects of physiological state on the AMPK activity in hindbrain nucleus tractus solitarius (NTS) neurons because treatments that reduce energy availability in these neurons trigger behavioral, endocrine, and autonomic responses to restore energy balance. Food-deprived rats showed significantly increased AMPK activity in both NTS- and hypothalamus-enriched lysates compared with those that were ad libitum fed. Pharmacological inhibition of AMPK activity in medial NTS neurons, by intraparenchymal injection of compound C, suppressed food intake and body weight gain compared with vehicle. Fourth ventricle (4th i.c.v.) compound C delivery increased heart rate and spontaneous activity in free-moving rats. Suppression of AMPK activity has been implicated in leptin's anorectic action in the hypothalamus. Given the role of leptin signaling in food intake inhibition within the medial NTS, we also examined whether stimulation of hindbrain AMPK by 4th i.c.v. administration of 5-aminoimidazole-4-carboxamide-riboside (AICAR), an AMP-mimicking promoter of AMPK activity, could attenuate the inhibition of food intake by 4th i.c.v. leptin. The intake-suppressive effects of leptin (at 2 and 4 h) were completely reversed by AICAR. We conclude that 1) hindbrain AMPK activity contributes to energy balance control through regulation of food intake and energy expenditure, 2) leptin's intake-reducing effects in the NTS are mediated by AMPK, and 3) central nervous system AMPK controls whole-body homeostasis at anatomically distributed sites across the neuraxis.
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Affiliation(s)
- Matthew R Hayes
- Graduate Group of Psychology, University of Pennsylvania, 3720 Walnut Street, Philadelphia, Pennsylvania 19104, USA.
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Lam DD, Zhou L, Vegge A, Xiu PY, Christensen BT, Osundiji MA, Yueh CY, Evans ML, Heisler LK. Distribution and neurochemical characterization of neurons within the nucleus of the solitary tract responsive to serotonin agonist-induced hypophagia. Behav Brain Res 2009; 196:139-43. [PMID: 18762217 PMCID: PMC2614086 DOI: 10.1016/j.bbr.2008.07.039] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 07/25/2008] [Accepted: 07/29/2008] [Indexed: 11/28/2022]
Abstract
Pharmacological compounds enhancing serotonergic tone significantly decrease food intake and are among the most clinically efficacious treatments for obesity. However, the central mechanisms through which serotonergic compounds modulate feeding behavior have not been fully defined. The primary relay center receiving visceral gastrointestinal information in the central nervous system is the nucleus of the solitary tract (NTS) in the caudal brainstem. Here we investigated whether the classic anorectic serotonin receptor agonist m-chloro-phenylpiperazine (mCPP) enhances the activity of metabolically sensitive NTS neurons. Using c-fos immunoreactivity (FOS-IR) as a marker of neuronal activation in rats, we observed that mCPP significantly and dose-dependently activated a discrete population of caudal NTS neurons at the level of the area postrema (AP). In particular, this pattern of FOS-IR induction was consistent with the location of catecholamine-containing neurons. Dual-labeling performed with FOS-IR and the catecholamine biosynthetic enzyme tyrosine hydroxylase (TH) revealed that mCPP induced FOS-IR in 83.7% of TH-IR containing neurons in the NTS at the level of the AP. The degree of activation of TH neurons was strongly negatively correlated with food intake. Moreover, this activation was specific to catecholamine neurons, with negligible induction of cocaine- and amphetamine-regulated transcript (CART), cholecystokinin (CCK), glucagon-like peptide 1 (GLP-1), or neurotensin neurons. NTS catecholaminergic neurons relay visceral gastrointestinal signals to both the lateral hypothalamus (LHA) and paraventricular nucleus of the hypothalamus (PVH), where these signals are integrated into autonomic and hormonal responses regulating food intake. The data presented here identify a novel mechanism through which a serotonin receptor agonist acting in the caudal brainstem may regulate ingestive behavior.
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Affiliation(s)
- Daniel D. Lam
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Ligang Zhou
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Andreas Vegge
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
- Department of Veterinary Pathobiology, Faculty of Life Sciences, University of Copenhagen, Dyrlaegevej 88, 1870 Frederiksberg, Denmark
| | - Philip Y. Xiu
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Britt T. Christensen
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
- Department of Veterinary Pathobiology, Faculty of Life Sciences, University of Copenhagen, Dyrlaegevej 88, 1870 Frederiksberg, Denmark
| | - Mayowa A. Osundiji
- Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 2QQ, UK
| | - Chen-yu Yueh
- Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 2QQ, UK
- College of Medicine, Chang Gung University, Chang Gung Memorial Hospital, Chiayi, Taiwan, ROC
| | - Mark L. Evans
- Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 2QQ, UK
| | - Lora K. Heisler
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
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Someya N, Hayashi N. Chewing and taste increase blood velocity in the celiac but not the superior mesenteric arteries. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1921-5. [DOI: 10.1152/ajpregu.90493.2008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate the role of chewing and taste in the meal-induced rapid increase in splanchnic blood flow, we compared the blood flow responses in the celiac artery (CA) and superior mesenteric artery (SMA) to chewing solid food with a chocolate taste (FOOD) and paraffin wax without taste (WAX). After 5 min of baseline measurement, 15 healthy subjects repeated chewing and expectorating the FOOD or WAX every 20 s for 4 min followed by 10 min of recovery measurement. We measured the mean blood velocity (MBV) in the CA and SMA. The baseline MBVs in the CA and SMA did not differ between the FOOD and WAX trials. The MBV in the CA was lower than baseline at the 1st min of chewing in both trials. It was higher than baseline at the 3rd min of FOOD chewing, whereas it did not increase during and after WAX chewing. The MBV in the CA was higher in the FOOD trial than in the WAX trial at the 3rd min of chewing and thereafter. In contrast, the MBV in the SMA did not change throughout the protocols. These results suggest that the taste of food plays a role in meal-induced hyperemia in the CA but not the SMA.
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Effects of oral fat perception by modified sham feeding on energy expenditure, hormones and appetite profile in the postprandial state. Br J Nutr 2008; 101:1360-8. [DOI: 10.1017/s0007114508079592] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
The article presents a brief overview of the responses of the GI tract and its associated pancreatic and biliary systems to a meal. These responses are specifically regulated by complex and interacting neural, hormonal, and parcrine pathways. Stimuli for various responses are multiple and include anticipation, senses of olfaction, taste and hearing, and chemical and mechanical stimuli of meal constituents. The overall result of the integrated response is assimilation of nutrients and elimination of wastes from the GI tract.
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Affiliation(s)
- Stephen J Pandol
- Department of Veterans Affairs, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA.
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Power ML, Schulkin J. Anticipatory physiological regulation in feeding biology: cephalic phase responses. Appetite 2008; 50:194-206. [PMID: 18045735 PMCID: PMC2297467 DOI: 10.1016/j.appet.2007.10.006] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 10/05/2007] [Accepted: 10/18/2007] [Indexed: 12/19/2022]
Abstract
Anticipatory physiological regulation is an adaptive strategy that enables animals to respond faster to physiologic and metabolic challenges. The cephalic phase responses are anticipatory responses that prepare animals to digest, absorb, and metabolize nutrients. They enable the sensory aspects of the food to interact with the metabolic state of the animal to influence feeding behavior. The anticipatory digestive secretions and metabolic adjustments in response to food cues are key adaptations that affect digestive and metabolic efficiency and aid in controlling the resulting elevation of metabolic fuels in the blood. Cephalic phase responses enable digestion, metabolism, and appetite to be regulated in a coordinated fashion. These responses have significant effects on meal size. For example, if the cephalic phase insulin response is blocked the result is poor glucose control and smaller meals. Cephalic phase responses also are linked to motivation to feed, and may play a more direct role in regulating meal size beyond the permissive one of ameliorating negative consequences of feeding. For example, the orexigenic peptide ghrelin appears to display a cephalic phase response, rising before expected meal times. This anticipatory ghrelin response increases appetite; interestingly it also enhances fat absorption, linking appetite with digestion and metabolism.
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Affiliation(s)
- Michael L Power
- Research Department, American College of Obstetricians and Gynecologists, 409 12th Street, SW, Washington, DC 20024, USA.
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Novak CM, Levine JA. Central neural and endocrine mechanisms of non-exercise activity thermogenesis and their potential impact on obesity. J Neuroendocrinol 2007; 19:923-40. [PMID: 18001322 DOI: 10.1111/j.1365-2826.2007.01606.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The rise in obesity is associated with a decline in the amount of physical activity in which people engage. The energy expended through everyday non-exercise activity, called non-exercise activity thermogenesis (NEAT), has a considerable potential impact on energy balance and weight gain. Comparatively little attention has been paid to the central mechanisms of energy expenditure and how decreases in NEAT might contribute to obesity. In this review, we first examine the sensory and endocrine mechanisms through which energy availability and energy balance are detected that may influence NEAT. Second, we describe the neural pathways that integrate these signals. Lastly, we consider the effector mechanisms that modulate NEAT through the alteration of activity levels as well as through changes in the energy efficiency of movement. Systems that regulate NEAT according to energy balance may be linked to neural circuits that modulate sleep, addiction and the stress response. The neural and endocrine systems that control NEAT are potential targets for the treatment of obesity.
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Affiliation(s)
- C M Novak
- Mayo Clinic, Endocrine Research Unit, Rochester, MN, USA.
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Donadio V, Liguori R, Vetrugno R, Contin M, Elam M, Wallin BG, Karlsson T, Bugiardini E, Baruzzi A, Montagna P. Daytime sympathetic hyperactivity in OSAS is related to excessive daytime sleepiness. J Sleep Res 2007; 16:327-32. [PMID: 17716282 DOI: 10.1111/j.1365-2869.2007.00602.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The aim of this study was to investigate the relationships among sympathetic hyperactivity, excessive daytime sleepiness (EDS) and hypertension in obstructive sleep apnoea syndrome (OSAS). Ten newly diagnosed OSAS patients with untreated EDS and daytime hypertension underwent polysomnography (PSG) and daytime measurements of plasma noradrenaline (NA), ambulatory blood pressure (BP), muscle sympathetic nerve activity (MSNA) by microneurography and objective assessment of EDS before and during 6 months of compliance-monitored continuous positive airway pressure (CPAP) treatment. One month after the start of CPAP, BP, MSNA and NA were significantly lowered, remaining lower than baseline also after 3 and 6 months of treatment. CPAP use caused a significant improvement of sleep structures, and reduced EDS. A statistical correlation analysis demonstrated that EDS was not correlated with sleep measures obtained from baseline PSG (% sleep stages, apnoea and arousal index, mean oxygen saturation value), whereas daytime sleepiness was significantly correlated with MSNA. Furthermore, MSNA and BP showed no correlation. Our data obtained from selected patients suggest that the mechanisms inducing EDS in OSAS are related to the degree of daytime sympathetic hyperactivity. Additionally, resting MSNA was unrelated to BP suggesting that factors other than adrenergic neural tone make a major contribution to OSAS-related hypertension. The results obtained in this pilot study need, however, to be confirmed in a larger study involving more patients.
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Affiliation(s)
- Vincenzo Donadio
- Department of Neurological Sciences, University of Bologna, Bologna, Italy.
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Abstract
Human food intake is driven by necessity, but modern industrialized societies are characterized by food surfeit and an increasingly ‘obesogenic’ environment. This environment tends to discourage energy expenditure and to facilitate energy intake. The amount eaten in any given eating episode depends less on internal need state and more on environmental contextual factors such as the availability of highly-palatable energy-dense foods. In addition, the process of satiation can easily be disrupted by the introduction within a meal of different foods (variety effect), the presence of others (social context) and competing tasks (distraction). Properties of ingestants such as alcohol promote food intake and characteristics of individuals make them more or less susceptible to situational cues to overeat. In the present review the role of each of these environmental factors in promoting overconsumption are considered and the extent to which these factors might contribute to long-term weight regulation is discussed.
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Affiliation(s)
- Marion M Hetherington
- Department of Psychology, Glasgow Caledonian University, School of Life Sciences, George Moore Building, Cowcaddens Road, Glasgow G4 0BA, UK.
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Balfour RH, Trapp S. Ionic currents underlying the response of rat dorsal vagal neurones to hypoglycaemia and chemical anoxia. J Physiol 2007; 579:691-702. [PMID: 17218356 PMCID: PMC2151378 DOI: 10.1113/jphysiol.2006.126094] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
A proportion of dorsal vagal neurones (DVN) are glucosensors. These cells respond to brief hypoglycaemia either with a K(ATP) channel-mediated hyperpolarization or with depolarization owing to an as yet unknown mechanism. K(ATP) currents are observed not only during hypoglycaemia, but also in response to mitochondrial inhibition. Here we show that similarly to the observations for K(ATP) currents, both hypoglycaemia and inhibition of mitochondrial function elicited a small inward current that persisted in TTX in DVN of rat brainstem slices. Removal of glucose from the bath solution induced this inward current within 50 +/- 4 s in one subpopulation of DVN and in 279 +/- 36 s in another subpopulation. No such subpopulations were observed for the response to mitochondrial inhibition. Biophysical analysis revealed that mitochondrial inhibition or hypoglycaemia inhibited an openly rectifying K+ conductance in 25% of DVN. In the remaining cells, either an increase in conductance, with a reversal potential between -58 and +10 mV, or a parallel inward shift of the holding current was observed. This current most probably resulted from inhibition of the Na+-K+-ATPase and/or the opening of an ion channel. Recordings with electrodes containing 145 mm instead of 5 mm Cl- failed to shift the reversal potential of the inward current, indicating that a Cl- channel was not involved. In summary, glucosensing and non-glucosensing DVN appear to use common electrical pathways to respond to mitochondrial inhibition and to hypoglycaemia. We suggest that differences in glucose metabolism rather than differences in the complement of ion channels distinguish these two cell types.
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Affiliation(s)
- Robert H Balfour
- Department of Anaesthetics, Pain Medicine and Intensive Care, Chelsea & Westminster Hospital, Imperial College London, UK
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Pecoraro N, Dallman MF, Warne JP, Ginsberg AB, Laugero KD, la Fleur SE, Houshyar H, Gomez F, Bhargava A, Akana SF. From Malthus to motive: how the HPA axis engineers the phenotype, yoking needs to wants. Prog Neurobiol 2006; 79:247-340. [PMID: 16982128 DOI: 10.1016/j.pneurobio.2006.07.004] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 07/17/2006] [Accepted: 07/24/2006] [Indexed: 01/28/2023]
Abstract
The hypothalamo-pituitary-adrenal (HPA) axis is the critical mediator of the vertebrate stress response system, responding to environmental stressors by maintaining internal homeostasis and coupling the needs of the body to the wants of the mind. The HPA axis has numerous complex drivers and highly flexible operating characterisitics. Major drivers include two circadian drivers, two extra-hypothalamic networks controlling top-down (psychogenic) and bottom-up (systemic) threats, and two intra-hypothalamic networks coordinating behavioral, autonomic, and neuroendocrine outflows. These various networks jointly and flexibly control HPA axis output of periodic (oscillatory) functions and a range of adventitious systemic or psychological threats, including predictable daily cycles of energy flow, actual metabolic deficits over many time scales, predicted metabolic deficits, and the state-dependent management of post-prandial responses to feeding. Evidence is provided that reparation of metabolic derangement by either food or glucocorticoids results in a metabolic signal that inhibits HPA activity. In short, the HPA axis is intimately involved in managing and remodeling peripheral energy fluxes, which appear to provide an unidentified metabolic inhibitory feedback signal to the HPA axis via glucocorticoids. In a complementary and perhaps a less appreciated role, adrenocortical hormones also act on brain to provide not only feedback, but feedforward control over the HPA axis itself and its various drivers, as well as coordinating behavioral and autonomic outflows, and mounting central incentive and memorial networks that are adaptive in both appetitive and aversive motivational modes. By centrally remodeling the phenotype, the HPA axis provides ballistic and predictive control over motor outflows relevant to the type of stressor. Evidence is examined concerning the global hypothesis that the HPA axis comprehensively induces integrative phenotypic plasticity, thus remodeling the body and its governor, the brain, to yoke the needs of the body to the wants of the mind. Adverse side effects of this yoking under conditions of glucocorticoid excess are discussed.
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Affiliation(s)
- Norman Pecoraro
- Department of Physiology, University of California, San Francisco, CA 94143-0444, United States.
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Robertson MD. Food perception and postprandial lipid metabolism. Physiol Behav 2006; 89:4-9. [PMID: 16556452 DOI: 10.1016/j.physbeh.2006.01.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 01/06/2006] [Accepted: 01/06/2006] [Indexed: 10/24/2022]
Abstract
The postprandial response to macronutrients in the diet, particularly carbohydrates and fats, underpins the detrimental changes in metabolism (impaired glucose tolerance or postprandial hyperlipaemia) and later pathology (insulin resistance, type 2 diabetes or atherosclerosis) associated with Westernised diets. Research has shown that in addition to what and how much we eat, eating behaviour in itself may be implicated in postprandial regulation. The process of ingestion stimulates cholinergic-vagal activity, irrespective of what is eaten, important in determining both the absorption and subsequent utilisation of nutrients but also potentially food intake through effects on hunger and satiety. Modifications in this aspect of physiology have the potential to influence all aspects of postprandial metabolism and subsequent disease risk in humans.
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Affiliation(s)
- M D Robertson
- School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK.
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Camilleri M. Integrated upper gastrointestinal response to food intake. Gastroenterology 2006; 131:640-58. [PMID: 16890616 DOI: 10.1053/j.gastro.2006.03.023] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Accepted: 03/16/2006] [Indexed: 12/14/2022]
Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.) Group, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
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ZAFRA M, MOLINA F, PUERTO A. The neural/cephalic phase reflexes in the physiology of nutrition. Neurosci Biobehav Rev 2006; 30:1032-44. [DOI: 10.1016/j.neubiorev.2006.03.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 03/15/2006] [Accepted: 03/16/2006] [Indexed: 10/24/2022]
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