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Sclafani A, Castillo A, Carata I, Pines R, Berglas E, Joseph S, Sarker J, Nashed M, Roland M, Arzayus S, Williams N, Glendinning JI, Bodnar RJ. Conditioned preference and avoidance induced in mice by the rare sugars isomaltulose and allulose. Physiol Behav 2023; 267:114221. [PMID: 37146897 DOI: 10.1016/j.physbeh.2023.114221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 04/30/2023] [Accepted: 05/02/2023] [Indexed: 05/07/2023]
Abstract
Isomaltulose, a slowly digested isocaloric analog of sucrose, and allulose, a noncaloric fructose analog, are promoted as "healthful" sugar alternatives in human food products. Here we investigated the appetite and preference conditioning actions of these sugar analogs in inbred mouse strains. In brief-access lick tests (Experiment 1), C57BL/6 (B6) mice showed similar concentration dependent increases in licking for allulose and fructose, but less pronounced concentration-dependent increases in licking for isomaltulose than sucrose. In Experiment 2, B6 male were given one-bottle training with a CS+ flavor (e.g., grape) mixed with 8% isomaltulose or allulose and a CS- flavor (e.g., cherry) mixed in water followed by two-bottle CS flavor tests. The isomaltulose mice showed only a weak CS+ flavor preference but a strong preference for the sugar over water. The allulose mice strongly preferred the CS- flavor and water over the sugar. The allulose avoidance may be due to gut discomfort as reported in humans consuming high amounts of the sugar. Experiment 3 found that the preference for 8% sucrose over 8% isomaltulose could be reversed or blocked by adding different concentrations of a noncaloric sweetener mixture (sucralose + saccharin, SS) to the isomaltulose. Experiment 4 revealed that the preference of B6 or FVB/N mice for isomaltulose+0.01%SS or sucrose over 0.1%SS increased after separate experience with the sugars and SS. This indicates that isomaltulose, like sucrose, has postoral appetition effects that enhances the appetite for the sugar. In Experiments 5 and 6, the appetition actions of the two sugars were directly compared by giving mice isomaltulose+0.05%SS vs. sucrose choice tests before and after separate experience with the two sugars. In general, the initial preference the mice displayed for isomaltulose+0.05%SS was reduced or reversed after separate experience with the two sugars although some strain and sex differences were obtained. This indicates that isomaltulose has weaker postoral appetition effects than sucrose.
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Subramanian KS, Lauer LT, Hayes AMR, Décarie-Spain L, McBurnett K, Nourbash AC, Donohue KN, Kao AE, Bashaw AG, Burdakov D, Noble EE, Schier LA, Kanoski SE. Hypothalamic melanin-concentrating hormone neurons integrate food-motivated appetitive and consummatory processes in rats. Nat Commun 2023; 14:1755. [PMID: 36990984 PMCID: PMC10060386 DOI: 10.1038/s41467-023-37344-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 03/13/2023] [Indexed: 03/31/2023] Open
Abstract
The lateral hypothalamic area (LHA) integrates homeostatic processes and reward-motivated behaviors. Here we show that LHA neurons that produce melanin-concentrating hormone (MCH) are dynamically responsive to both food-directed appetitive and consummatory processes in male rats. Specifically, results reveal that MCH neuron Ca2+ activity increases in response to both discrete and contextual food-predictive cues and is correlated with food-motivated responses. MCH neuron activity also increases during eating, and this response is highly predictive of caloric consumption and declines throughout a meal, thus supporting a role for MCH neurons in the positive feedback consummatory process known as appetition. These physiological MCH neural responses are functionally relevant as chemogenetic MCH neuron activation promotes appetitive behavioral responses to food-predictive cues and increases meal size. Finally, MCH neuron activation enhances preference for a noncaloric flavor paired with intragastric glucose. Collectively, these data identify a hypothalamic neural population that orchestrates both food-motivated appetitive and intake-promoting consummatory processes.
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Affiliation(s)
- Keshav S Subramanian
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California, USA
| | - Logan Tierno Lauer
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
| | - Anna M R Hayes
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
| | - Léa Décarie-Spain
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
| | - Kara McBurnett
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
| | - Anna C Nourbash
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
| | - Kristen N Donohue
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
| | - Alicia E Kao
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
| | - Alexander G Bashaw
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California, USA
| | - Denis Burdakov
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Emily E Noble
- Department of Nutritional Sciences, University of Georgia, Athens, USA
| | - Lindsey A Schier
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California, USA
| | - Scott E Kanoski
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA.
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California, USA.
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3
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Differential fructose and glucose appetition in DBA/2, 129P3 and C57BL/6 × 129P3 hybrid mice revealed by sugar versus non-nutritive sweetener tests. Physiol Behav 2021; 241:113590. [PMID: 34509472 DOI: 10.1016/j.physbeh.2021.113590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/04/2021] [Accepted: 09/08/2021] [Indexed: 11/20/2022]
Abstract
Inbred mouse strains differ in their postoral appetite stimulating response (appetition) to fructose as demonstrated in intragastric (IG) sugar conditioning and oral sugar vs. nonnutritive conditioning experiments. For example, FVB and SWR strains show experience-induced preferences for 8% fructose over a 0.1% sucralose + 0.1% saccharin (S + S) solution, whereas C57BL/6 (B6) and BALB/c strains do not. All strains, however, learn to prefer 8% glucose to S + S after experience, which is attributed to the potent appetition actions of this sugar. The present study extended this analysis to DBA/2 (DBA) and 129P3 (129) inbred mice. In Experiment 1A, ad libitum fed DBA and 129 mice preferred S + S to fructose before and after separate experience with the two sweeteners, indicating an indifference to the postoral nutrient effects of the sugar. When food restricted (Experiment 1B), 129 mice continued to prefer S + S to fructose while DBA mice showed equal preference for the sweeteners after experience, indicating some sensitivity to fructose appetition. In Experiment 1C, both strains acquired significant preferences for glucose over S + S after experience, confirming their sensitivity to postoral glucose appetition. Experiment 2 revealed that C57BL/6 × 129P3 (B6:129) hybrid mice responded like inbred B6 mice and 129 mice in acquiring a preference for glucose but not fructose over S + S. This is of interest because sweet "taste-blind" P2 × 2 / P2 × 3 double-knockout (DKO) mice on a B6:129 genetic background prefer fructose to water in 24 h tests, which is indicative of fructose appetition. Whether differences in the genetic makeup of DKO and B6:129 hybrid mice or other factors explain the fructose appetition of the DKO mice remains to be determined.
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Lord MN, Subramanian K, Kanoski SE, Noble EE. Melanin-concentrating hormone and food intake control: Sites of action, peptide interactions, and appetition. Peptides 2021; 137:170476. [PMID: 33370567 PMCID: PMC8025943 DOI: 10.1016/j.peptides.2020.170476] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 12/10/2020] [Accepted: 12/14/2020] [Indexed: 12/12/2022]
Abstract
Given the increased prevalence of obesity and its associated comorbidities, understanding the mechanisms through which the brain regulates energy balance is of critical importance. The neuropeptide melanin-concentrating hormone (MCH) is produced in the lateral hypothalamic area and the adjacent incerto-hypothalamic area and promotes both food intake and energy conservation, overall contributing to body weight gain. Decades of research into this system has provided insight into the neural pathways and mechanisms (behavioral and neurobiological) through which MCH stimulates food intake. Recent technological advancements that allow for selective manipulation of MCH neuron activity have elucidated novel mechanisms of action for the hyperphagic effects of MCH, implicating neural "volume" transmission in the cerebrospinal fluid and sex-specific effects of MCH on food intake control as understudied areas for future investigation. Highlighted here are historical and recent findings that illuminate the neurobiological mechanisms through which MCH promotes food intake, including the identification of various specific neural signaling pathways and interactions with other peptide systems. We conclude with a framework that the hyperphagic effects of MCH signaling are predominantly mediated through enhancement of an "appetition" process in which early postoral prandial signals promote further caloric consumption.
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Affiliation(s)
- Magen N Lord
- Department of Foods and Nutrition, University of Georgia, Athens, GA 30606, USA
| | - Keshav Subramanian
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA
| | - Scott E Kanoski
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA; Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA.
| | - Emily E Noble
- Department of Foods and Nutrition, University of Georgia, Athens, GA 30606, USA.
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Lee J, Raycraft L, Johnson AW. The dynamic regulation of appetitive behavior through lateral hypothalamic orexin and melanin concentrating hormone expressing cells. Physiol Behav 2020; 229:113234. [PMID: 33130035 DOI: 10.1016/j.physbeh.2020.113234] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 02/07/2023]
Abstract
The lateral hypothalamic area (LHA) is a heterogeneous brain structure extensively studied for its potent role in regulating energy balance. The anatomical and molecular diversity of the LHA permits the orchestration of responses to energy sensing cues from the brain and periphery. Two of the primary cell populations within the LHA associated with integration of this information are Orexin (ORX) and Melanin Concentrating Hormone (MCH). While both of these non-overlapping populations exhibit orexigenic properties, the activities of these two systems support feeding behavior through contrasting mechanisms. We describe the anatomical and functional properties as well as interaction with other neuropeptides and brain reward and hedonic systems. Specific outputs relating to arousal, food seeking, feeding, and metabolism are coordinated through these mechanisms. We then discuss how both the ORX and MCH systems harmonize in a divergent yet overall cooperative manner to orchestrate feeding behavior through transitions between various appetitive states, and thus offer novel insights into LHA allostatic control of appetite.
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Affiliation(s)
| | | | - Alexander W Johnson
- Department of Psychology; Neuroscience Program, Michigan State University, East Lansing.
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6
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Bandaru SS, Khanday MA, Ibrahim N, Naganuma F, Vetrivelan R. Sleep-Wake Control by Melanin-Concentrating Hormone (MCH) Neurons: a Review of Recent Findings. Curr Neurol Neurosci Rep 2020; 20:55. [PMID: 33006677 DOI: 10.1007/s11910-020-01075-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/17/2020] [Indexed: 12/14/2022]
Abstract
PURPOSE OF THE REVIEW Melanin-concentrating hormone (MCH)-expressing neurons located in the lateral hypothalamus are considered as an integral component of sleep-wake circuitry. However, the precise role of MCH neurons in sleep-wake regulation has remained unclear, despite several years of research employing a wide range of techniques. We review recent data on this aspect, which are mostly inconsistent, and propose a novel role for MCH neurons in sleep regulation. RECENT FINDINGS While almost all studies using "gain-of-function" approaches show an increase in rapid eye movement sleep (or paradoxical sleep; PS), loss-of-function approaches have not shown reductions in PS. Similarly, the reported changes in wakefulness or non-rapid eye movement sleep (slow-wave sleep; SWS) with manipulation of the MCH system using conditional genetic methods are inconsistent. Currently available data do not support a role for MCH neurons in spontaneous sleep-wake but imply a crucial role for them in orchestrating sleep-wake responses to changes in external and internal environments.
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Affiliation(s)
- Sathyajit S Bandaru
- Department of Neurology, Beth Israel Deaconess Medical Center, 3 Blackfan Circle, Center for Life Science # 711, Boston, MA, USA
| | - Mudasir A Khanday
- Department of Neurology, Beth Israel Deaconess Medical Center, 3 Blackfan Circle, Center for Life Science # 711, Boston, MA, USA.,Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA
| | - Nazifa Ibrahim
- Department of Neurology, Beth Israel Deaconess Medical Center, 3 Blackfan Circle, Center for Life Science # 711, Boston, MA, USA.,Department of Public Health Sciences, University of Massachusetts, Amherst, MA, USA
| | - Fumito Naganuma
- Department of Neurology, Beth Israel Deaconess Medical Center, 3 Blackfan Circle, Center for Life Science # 711, Boston, MA, USA.,Division of Pharmacology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Ramalingam Vetrivelan
- Department of Neurology, Beth Israel Deaconess Medical Center, 3 Blackfan Circle, Center for Life Science # 711, Boston, MA, USA. .,Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA.
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Dilsiz P, Aklan I, Sayar Atasoy N, Yavuz Y, Filiz G, Koksalar F, Ates T, Oncul M, Coban I, Ates Oz E, Cebecioglu U, Alp MI, Yilmaz B, Atasoy D. MCH Neuron Activity Is Sufficient for Reward and Reinforces Feeding. Neuroendocrinology 2020; 110:258-270. [PMID: 31154452 DOI: 10.1159/000501234] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 05/31/2019] [Indexed: 11/19/2022]
Abstract
BACKGROUND Melanin-concentrating hormone (MCH)-expressing neurons have been implicated in regulation of energy homeostasis and reward, yet the role of their electrical activity in short-term appetite and reward modulation has not been fully understood. OBJECTIVES We investigated short-term behavioral and physiological effects of MCH neuron activity manipulations. METHODS We used optogenetic and chemogenetic approaches in Pmch-cre transgenic mice to acutely stimulate/inhibit MCH neuronal activity while probing feeding, locomotor activity, anxiety-like behaviors, glucose homeostasis, and reward. RESULTS MCH neuron activity is neither required nor sufficient for short-term appetite unless stimulation is temporally paired with consumption. MCH neuronal activation does not affect short-term locomotor activity, but inhibition improves glucose tolerance and is mildly anxiolytic. Finally, using two different operant tasks, we showed that activation of MCH neurons alone is sufficient to induce reward. CONCLUSIONS Our results confirm diverse behavioral/physiological functions of MCH neurons and suggest a direct role in reward function.
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Affiliation(s)
- Pelin Dilsiz
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Iltan Aklan
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Nilufer Sayar Atasoy
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Yavuz Yavuz
- Department of Physiology, School of Medicine, Yeditepe University, Istanbul, Turkey
| | - Gizem Filiz
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Fulya Koksalar
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Tayfun Ates
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Merve Oncul
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Ilknur Coban
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Edanur Ates Oz
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Utku Cebecioglu
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Muhammed Ikbal Alp
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Bayram Yilmaz
- Department of Physiology, School of Medicine, Yeditepe University, Istanbul, Turkey
| | - Deniz Atasoy
- Department of Physiology, School of Medicine, Regenerative and Restorative Medical Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey,
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA,
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8
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Novelle MG, Diéguez C. Unravelling the role and mechanism of adipokine and gastrointestinal signals in animal models in the nonhomeostatic control of energy homeostasis: Implications for binge eating disorder. EUROPEAN EATING DISORDERS REVIEW 2018; 26:551-568. [DOI: 10.1002/erv.2641] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/12/2018] [Accepted: 09/02/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Marta G. Novelle
- Department of Physiology, Centre for Research in Molecular Medicine and Chronic Diseases (CIMUS); University of Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III; Santiago de Compostela Spain
| | - Carlos Diéguez
- Department of Physiology, Centre for Research in Molecular Medicine and Chronic Diseases (CIMUS); University of Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III; Santiago de Compostela Spain
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9
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The convergence of psychology and neurobiology in flavor-nutrient learning. Appetite 2018; 122:36-43. [DOI: 10.1016/j.appet.2017.03.048] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 03/27/2017] [Accepted: 03/30/2017] [Indexed: 12/15/2022]
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10
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Sasaki T. Neural and Molecular Mechanisms Involved in Controlling the Quality of Feeding Behavior: Diet Selection and Feeding Patterns. Nutrients 2017; 9:nu9101151. [PMID: 29053636 PMCID: PMC5691767 DOI: 10.3390/nu9101151] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 10/12/2017] [Accepted: 10/13/2017] [Indexed: 12/20/2022] Open
Abstract
We are what we eat. There are three aspects of feeding: what, when, and how much. These aspects represent the quantity (how much) and quality (what and when) of feeding. The quantitative aspect of feeding has been studied extensively, because weight is primarily determined by the balance between caloric intake and expenditure. In contrast, less is known about the mechanisms that regulate the qualitative aspects of feeding, although they also significantly impact the control of weight and health. However, two aspects of feeding quality relevant to weight loss and weight regain are discussed in this review: macronutrient-based diet selection (what) and feeding pattern (when). This review covers the importance of these two factors in controlling weight and health, and the central mechanisms that regulate them. The relatively limited and fragmented knowledge on these topics indicates that we lack an integrated understanding of the qualitative aspects of feeding behavior. To promote better understanding of weight control, research efforts must focus more on the mechanisms that control the quality and quantity of feeding behavior. This understanding will contribute to improving dietary interventions for achieving weight control and for preventing weight regain following weight loss.
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Affiliation(s)
- Tsutomu Sasaki
- Laboratory for Metabolic Signaling, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi, Gunma 371-8512, Japan.
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11
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Sclafani A, Vural AS, Ackroff K. CAST/EiJ and C57BL/6J Mice Differ in Their Oral and Postoral Attraction to Glucose and Fructose. Chem Senses 2017; 42:259-267. [PMID: 28158517 DOI: 10.1093/chemse/bjx003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A recent study indicated that CAST/EiJ and C57BL/6J mice differ in their taste preferences for maltodextrin but display similar sucrose preferences. The present study revealed strain differences in preferences for the constituent sugars of sucrose. Whereas B6 mice preferred 8% glucose to 8% fructose in 2-day tests, the CAST mice preferred fructose to glucose. These preferences emerged with repeated testing which suggested post-oral influences. In a second experiment, 2-day choice tests were conducted with the sugars versus a sucralose + saccharin (SS) mixture which is highly preferred in brief access tests. B6 mice strongly preferred glucose but not fructose to the non-nutritive SS whereas CAST mice preferred SS to both glucose and fructose even when food restricted. This implied that CAST mice are insensitive to the postoral appetite stimulating actions of the 2 sugars. A third experiment revealed, however, that intragastric glucose and fructose infusions conditioned significant but mild flavor preferences in CAST mice, whereas in B6 mice glucose conditioned a robust preference but fructose was ineffective. Thus, unlike other mouse strains and rats, glucose is not more reinforcing than fructose in CAST mice. Their oral preference for fructose over glucose may be related to a subsensitive maltodextrin receptor or glucose-specific receptor which is stimulated by glucose but not fructose. The failure of CAST mice to prefer glucose to a non-nutritive sweetener distinguishes this strain from other mouse strains and rats.
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Affiliation(s)
- Anthony Sclafani
- Department of Psychology, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
| | - Austin S Vural
- Department of Psychology, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
| | - Karen Ackroff
- Department of Psychology, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
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12
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Flavor preferences conditioned by nutritive and non-nutritive sweeteners in mice. Physiol Behav 2017; 173:188-199. [PMID: 28192132 DOI: 10.1016/j.physbeh.2017.02.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 01/18/2017] [Indexed: 01/08/2023]
Abstract
Recent studies suggest that preferences are conditioned by nutritive (sucrose) but not by non-nutritive (sucralose) sweeteners in mice. Here we compared the effectiveness of nutritive and non-nutritive sweeteners to condition flavor preferences in three mouse strains. Isopreferred sucrose and sucralose solutions both conditioned flavor preferences in C57BL/6J (B6) mice but sucrose was more effective, consistent with its post-oral appetition action. Subsequent experiments compared flavor conditioning by fructose, which has no post-oral appetition effect in B6 mice, and a sucralose+saccharin mixture (SS) which is highly preferred to fructose in 24-h choice tests. Both sweeteners conditioned flavor preferences but fructose induced stronger preferences than SS. Training B6 mice to drink a flavored SS solution paired with intragastric fructose infusions did not enhance the SS-conditioned preference. Thus, the post-oral nutritive actions of fructose do not explain the sugar's stronger preference conditioning effect. Training B6 mice to drink a flavored fructose solution containing SS did not reduce the sugar-conditioned preference, indicating that SS does not have an off-taste that attenuates conditioning. Although B6 mice strongly preferred flavored SS to flavored fructose in a direct choice test, they preferred the fructose-paired flavor to the SS-paired flavor when these were presented in water. Fructose conditioned a stronger flavor preference than an isopreferred saccharin solution, indicating that sucralose is not responsible for the limited SS conditioning actions. SS is highly preferred by FVB/NJ and CAST/EiJ inbred mice, yet conditioned only weak flavor preferences. It is unclear why highly or equally preferred non-nutritive sweeteners condition weaker preferences than fructose, when all stimulate the same T1r2/T1r3 sweet receptor. Recent findings support the existence of non-T1r2/T1r3 glucose taste sensors; however, there is no evidence for receptors that respond to fructose but not to non-nutritive sweeteners.
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13
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Devarakonda K, Mobbs CV. Mechanisms and significance of brain glucose signaling in energy balance, glucose homeostasis, and food-induced reward. Mol Cell Endocrinol 2016; 438:61-69. [PMID: 27637346 DOI: 10.1016/j.mce.2016.09.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 09/12/2016] [Accepted: 09/12/2016] [Indexed: 12/15/2022]
Abstract
The concept that hypothalamic glucose signaling plays an important role in regulating energy balance, e.g., as instantiated in the so-called "glucostat" hypothesis, is one of the oldest in the field of metabolism. However the mechanisms by which neurons in the hypothalamus sense glucose, and the function of glucose signaling in the brain, has been difficult to establish. Nevertheless recent studies probing mechanisms of glucose signaling have also strongly supported a role for glucose signaling in regulating energy balance, glucose homeostasis, and food-induced reward.
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Affiliation(s)
- Kavya Devarakonda
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, 1470 Madison Ave., 9-119, New York, NY 10029, USA; Department of Endocrinology, Icahn School of Medicine at Mount Sinai, 1470 Madison Ave., 9-119, New York, NY 10029, USA
| | - Charles V Mobbs
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, 1470 Madison Ave., 9-119, New York, NY 10029, USA; Department of Endocrinology, Icahn School of Medicine at Mount Sinai, 1470 Madison Ave., 9-119, New York, NY 10029, USA; Department of Geriatrics, Icahn School of Medicine at Mount Sinai, 1470 Madison Ave., 9-119, New York, NY 10029, USA.
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