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Mendez-Hernandez R, Braga I, Bali A, Yang M, de Lartigue G. Vagal Sensory Gut-Brain Pathways That Control Eating-Satiety and Beyond. Compr Physiol 2025; 15:e70010. [PMID: 40229922 DOI: 10.1002/cph4.70010] [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: 02/03/2025] [Revised: 03/20/2025] [Accepted: 03/31/2025] [Indexed: 04/16/2025]
Abstract
The vagus nerve is the body's primary sensory conduit from gut to brain, traditionally viewed as a passive relay for satiety signals. However, emerging evidence reveals a far more complex system-one that actively encodes diverse aspects of meal-related information, from mechanical stretch to nutrient content, metabolic state, and even microbial metabolites. This review challenges the view of vagal afferent neurons (VANs) as simple meal-termination sensors and highlights their specialized subpopulations, diverse sensory modalities, and downstream brain circuits, which shape feeding behavior, metabolism, and cognition. We integrate recent advances from single-cell transcriptomics, neural circuit mapping, and functional imaging to examine how VANs contribute to gut-brain communication beyond satiety, including their roles in food reward and memory formation. By synthesizing the latest research and highlighting emerging directions for the field, this review provides a comprehensive update on vagal sensory pathways and their role as integrators of meal information.
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Affiliation(s)
- Rebeca Mendez-Hernandez
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, USA
- Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Isadora Braga
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, USA
- Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Avnika Bali
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, USA
- Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Mingxin Yang
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, USA
- Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Guillaume de Lartigue
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, USA
- Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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2
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Fox EA, Serlin HK. Gaps in our understanding of how vagal afferents to the small intestinal mucosa detect luminal stimuli. Am J Physiol Regul Integr Comp Physiol 2024; 327:R173-R187. [PMID: 38860288 DOI: 10.1152/ajpregu.00252.2023] [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: 11/13/2023] [Revised: 05/10/2024] [Accepted: 05/24/2024] [Indexed: 06/12/2024]
Abstract
Vagal afferents to the gastrointestinal tract are crucial for the regulation of food intake, signaling negative feedback that contributes to satiation and positive feedback that produces appetition and reward. Vagal afferents to the small intestinal mucosa contribute to this regulation by sensing luminal stimuli and reporting this information to the brain. These afferents respond to mechanical, chemical, thermal, pH, and osmolar stimuli, as well as to bacterial products and immunogens. Surprisingly, little is known about how these stimuli are transduced by vagal mucosal afferents or how their transduction is organized among these afferents' terminals. Furthermore, the effects of stimulus concentration ranges or physiological stimuli on vagal activity have not been examined for some of these stimuli. Also, detection of luminal stimuli has rarely been examined in rodents, which are most frequently used for studying small intestinal innervation. Here we review what is known about stimulus detection by vagal mucosal afferents and illustrate the complexity of this detection using nutrients as an exemplar. The accepted model proposes that nutrients bind to taste receptors on enteroendocrine cells (EECs), which excite them, causing the release of hormones that stimulate vagal mucosal afferents. However, evidence reviewed here suggests that although this model accounts for many aspects of vagal signaling about nutrients, it cannot account for all aspects. A major goal of this review is therefore to evaluate what is known about nutrient absorption and detection and, based on this evaluation, identify candidate mucosal cells and structures that could cooperate with EECs and vagal mucosal afferents in stimulus detection.
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Affiliation(s)
- Edward A Fox
- Behavioral Neurogenetics Laboratory, Department of Psychological Sciences, Purdue University, West Lafayette, Indiana, United States
| | - Hannah K Serlin
- Behavioral Neurogenetics Laboratory, Department of Psychological Sciences, Purdue University, West Lafayette, Indiana, United States
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3
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Berthoud HR, Münzberg H, Morrison CD, Neuhuber WL. Hepatic interoception in health and disease. Auton Neurosci 2024; 253:103174. [PMID: 38579493 PMCID: PMC11129274 DOI: 10.1016/j.autneu.2024.103174] [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: 12/19/2023] [Revised: 03/14/2024] [Accepted: 03/28/2024] [Indexed: 04/07/2024]
Abstract
The liver is a large organ with crucial functions in metabolism and immune defense, as well as blood homeostasis and detoxification, and it is clearly in bidirectional communication with the brain and rest of the body via both neural and humoral pathways. A host of neural sensory mechanisms have been proposed, but in contrast to the gut-brain axis, details for both the exact site and molecular signaling steps of their peripheral transduction mechanisms are generally lacking. Similarly, knowledge about function-specific sensory and motor components of both vagal and spinal access pathways to the hepatic parenchyma is missing. Lack of progress largely owes to controversies regarding selectivity of vagal access pathways and extent of hepatocyte innervation. In contrast, there is considerable evidence for glucose sensors in the wall of the hepatic portal vein and their importance for glucose handling by the liver and the brain and the systemic response to hypoglycemia. As liver diseases are on the rise globally, and there are intriguing associations between liver diseases and mental illnesses, it will be important to further dissect and identify both neural and humoral pathways that mediate hepatocyte-specific signals to relevant brain areas. The question of whether and how sensations from the liver contribute to interoceptive self-awareness has not yet been explored.
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Affiliation(s)
- Hans-Rudolf Berthoud
- Neurobiology of Nutrition & Metabolism Department, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA.
| | - Heike Münzberg
- Neurobiology of Nutrition & Metabolism Department, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA
| | - Christopher D Morrison
- Neurobiology of Nutrition & Metabolism Department, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA
| | - Winfried L Neuhuber
- Institute for Anatomy and Cell Biology, Friedrich-Alexander University, Erlangen, Germany.
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Choi PP, Wang Q, Brenner LA, Li AJ, Ritter RC, Appleyard SM. Lesion of NPY Receptor-expressing Neurons in Perifornical Lateral Hypothalamus Attenuates Glucoprivic Feeding. Endocrinology 2024; 165:bqae021. [PMID: 38368624 PMCID: PMC11043786 DOI: 10.1210/endocr/bqae021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 01/19/2024] [Accepted: 02/15/2024] [Indexed: 02/20/2024]
Abstract
Glucoprivic feeding is one of several counterregulatory responses (CRRs) that facilitates restoration of euglycemia following acute glucose deficit (glucoprivation). Our previous work established that glucoprivic feeding requires ventrolateral medullary (VLM) catecholamine (CA) neurons that coexpress neuropeptide Y (NPY). However, the connections by which VLM CA/NPY neurons trigger increased feeding are uncertain. We have previously shown that glucoprivation, induced by an anti-glycolygic agent 2-deoxy-D-glucose (2DG), activates perifornical lateral hypothalamus (PeFLH) neurons and that expression of NPY in the VLM CA/NPY neurons is required for glucoprivic feeding. We therefore hypothesized that glucoprivic feeding and possibly other CRRs require NPY-sensitive PeFLH neurons. To test this, we used the ribosomal toxin conjugate NPY-saporin (NPY-SAP) to selectively lesion NPY receptor-expressing neurons in the PeFLH of male rats. We found that NPY-SAP destroyed a significant number of PeFLH neurons, including those expressing orexin, but not those expressing melanin-concentrating hormone. The PeFLH NPY-SAP lesions attenuated 2DG-induced feeding but did not affect 2DG-induced increase in locomotor activity, sympathoadrenal hyperglycemia, or corticosterone release. The 2DG-induced feeding response was also significantly attenuated in NPY-SAP-treated female rats. Interestingly, PeFLH NPY-SAP lesioned male rats had reduced body weights and decreased dark cycle feeding, but this effect was not seen in female rats. We conclude that a NPY projection to the PeFLH is necessary for glucoprivic feeding, but not locomotor activity, hyperglycemia, or corticosterone release, in both male and female rats.
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Affiliation(s)
- Pique P Choi
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
| | - Qing Wang
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
| | - Lynne A Brenner
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
| | - Ai-Jun Li
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
| | - Robert C Ritter
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
| | - Suzanne M Appleyard
- Neuroscience Program, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
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5
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Watts AG, Kanoski SE, Sanchez-Watts G, Langhans W. The physiological control of eating: signals, neurons, and networks. Physiol Rev 2022; 102:689-813. [PMID: 34486393 PMCID: PMC8759974 DOI: 10.1152/physrev.00028.2020] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 08/30/2021] [Indexed: 02/07/2023] Open
Abstract
During the past 30 yr, investigating the physiology of eating behaviors has generated a truly vast literature. This is fueled in part by a dramatic increase in obesity and its comorbidities that has coincided with an ever increasing sophistication of genetically based manipulations. These techniques have produced results with a remarkable degree of cell specificity, particularly at the cell signaling level, and have played a lead role in advancing the field. However, putting these findings into a brain-wide context that connects physiological signals and neurons to behavior and somatic physiology requires a thorough consideration of neuronal connections: a field that has also seen an extraordinary technological revolution. Our goal is to present a comprehensive and balanced assessment of how physiological signals associated with energy homeostasis interact at many brain levels to control eating behaviors. A major theme is that these signals engage sets of interacting neural networks throughout the brain that are defined by specific neural connections. We begin by discussing some fundamental concepts, including ones that still engender vigorous debate, that provide the necessary frameworks for understanding how the brain controls meal initiation and termination. These include key word definitions, ATP availability as the pivotal regulated variable in energy homeostasis, neuropeptide signaling, homeostatic and hedonic eating, and meal structure. Within this context, we discuss network models of how key regions in the endbrain (or telencephalon), hypothalamus, hindbrain, medulla, vagus nerve, and spinal cord work together with the gastrointestinal tract to enable the complex motor events that permit animals to eat in diverse situations.
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Affiliation(s)
- Alan G Watts
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Scott E Kanoski
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Graciela Sanchez-Watts
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Wolfgang Langhans
- Physiology and Behavior Laboratory, Eidgenössische Technische Hochschule-Zürich, Schwerzenbach, Switzerland
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Berland C, Small DM, Luquet S, Gangarossa G. Dietary lipids as regulators of reward processes: multimodal integration matters. Trends Endocrinol Metab 2021; 32:693-705. [PMID: 34148784 DOI: 10.1016/j.tem.2021.05.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 05/08/2021] [Accepted: 05/24/2021] [Indexed: 02/03/2023]
Abstract
The abundance of energy-dense and palatable diets in the modern food environment tightly contributes to the obesity pandemic. The reward circuit participates to the regulation of body homeostasis by integrating energy-related signals with neural substrates encoding cognitive and motivational components of feeding behaviors. Obesity and lipid-rich diets alter dopamine (DA) transmission leading to reward dysfunctions and food overconsumption. Recent reports indicate that dietary lipids can act, directly and indirectly, as functional modulators of the DA circuit. This raises the possibility that nutritional or genetic conditions affecting 'lipid sensing' mechanisms might lead to maladaptations of the DA system. Here, we discuss the most recent findings connecting dietary lipid sensing with DA signaling and its multimodal influence on circuits regulating food-reward processes.
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Affiliation(s)
- Chloé Berland
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France; Department of Medicine, The Naomi Berrie Diabetes Center, Columbia University, New York, NY 10032, USA
| | - Dana M Small
- Department of Psychiatry, and the Modern Diet and Physiology Research Center, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Serge Luquet
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France.
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McDougle M, Quinn D, Diepenbroek C, Singh A, de la Serre C, de Lartigue G. Intact vagal gut-brain signalling prevents hyperphagia and excessive weight gain in response to high-fat high-sugar diet. Acta Physiol (Oxf) 2021; 231:e13530. [PMID: 32603548 PMCID: PMC7772266 DOI: 10.1111/apha.13530] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 06/23/2020] [Accepted: 06/23/2020] [Indexed: 01/02/2023]
Abstract
Aim The tools that have been used to assess the function of the vagus nerve lack specificity. This could explain discrepancies about the role of vagal gut‐brain signalling in long‐term control of energy balance. Here we use a validated approach to selectively ablate sensory vagal neurones that innervate the gut to determine the role of vagal gut‐brain signalling in the control of food intake, energy expenditure and glucose homoeostasis in response to different diets. Methods Rat nodose ganglia were injected bilaterally with either the neurotoxin saporin conjugated to the gastrointestinal hormone cholecystokinin (CCK), or unconjugated saporin as a control. Food intake, body weight, glucose tolerance and energy expenditure were measured in both groups in response to chow or high‐fat high‐sugar (HFHS) diet. Willingness to work for fat or sugar was assessed by progressive ratio for orally administered solutions, while post‐ingestive feedback was tested by measuring food intake after an isocaloric lipid or sucrose pre‐load. Results Vagal deafferentation of the gut increases meal number in lean chow‐fed rats. Switching to a HFHS diet exacerbates overeating and body weight gain. The breakpoint for sugar or fat solution did not differ between groups, suggesting that increased palatability may not drive HFHS‐induced hyperphagia. Instead, decreased satiation in response to intra‐gastric infusion of fat, but not sugar, promotes hyperphagia in CCK‐Saporin‐treated rats fed with HFHS diet. Conclusions We conclude that intact sensory vagal neurones prevent hyperphagia and exacerbation of weight gain in response to a HFHS diet by promoting lipid‐mediated satiation.
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Affiliation(s)
- Molly McDougle
- Department of Pharmacodynamics University of Florida Gainesville FL USA
- Center for Integrative Cardiovascular and Metabolic Disease University of Florida Gainesville FL USA
- The John B. Pierce Laboratory New Haven CT USA
| | | | - Charlene Diepenbroek
- The John B. Pierce Laboratory New Haven CT USA
- Department of Cellular and Molecular Physiology Yale Medical School New Haven CT USA
| | - Arashdeep Singh
- Department of Pharmacodynamics University of Florida Gainesville FL USA
- Center for Integrative Cardiovascular and Metabolic Disease University of Florida Gainesville FL USA
| | | | - Guillaume de Lartigue
- Department of Pharmacodynamics University of Florida Gainesville FL USA
- Center for Integrative Cardiovascular and Metabolic Disease University of Florida Gainesville FL USA
- The John B. Pierce Laboratory New Haven CT USA
- Department of Cellular and Molecular Physiology Yale Medical School New Haven CT USA
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8
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Omega 3 fatty acids stimulate thermogenesis during torpor in the Arctic Ground Squirrel. Sci Rep 2021; 11:1340. [PMID: 33446684 PMCID: PMC7809411 DOI: 10.1038/s41598-020-78763-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 10/20/2020] [Indexed: 11/29/2022] Open
Abstract
Omega 3 polyunsaturated fatty acids (PUFAs) influence metabolism and thermogenesis in non-hibernators. How omega 3 PUFAs influence Arctic Ground Squirrels (AGS) during hibernation is unknown. Prior to hibernation we fed AGS chow composed of an omega 6:3 ratio approximately 1:1 (high in omega 3 PUFA, termed Balanced Diet), or an omega 6:3 ratio of 5:1 (Standard Rodent Chow), and measured the influence of diet on core body temperature (Tb), brown adipose tissue (BAT) mass, fatty acid profiles of BAT, white adipose tissue (WAT) and plasma as well as hypothalamic endocannabinoid and endocannabinoid-like bioactive fatty acid amides during hibernation. Results show feeding a diet high in omega 3 PUFAs, with a more balanced omega 6:3 ratio, increases AGS Tb in torpor. We found the diet-induced increase in Tb during torpor is most easily explained by an increase in the mass of BAT deposits of Balanced Diet AGS. The increase in BAT mass is associated with elevated levels of metabolites DHA and EPA in tissue and plasma suggesting that these omega 3 PUFAs may play a role in thermogenesis during torpor. While we did not observe diet-induced change in endocannabinoids, we do report altered hypothalamic levels of some endocannabinoids, and endocannabinoid-like compounds, during hibernation.
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Velasco C, Conde-Sieira M, Comesaña S, Chivite M, Díaz-Rúa A, Míguez JM, Soengas JL. The long-chain fatty acid receptors FFA1 and FFA4 are involved in food intake regulation in fish brain. J Exp Biol 2020; 223:jeb227330. [PMID: 32665445 DOI: 10.1242/jeb.227330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/08/2020] [Indexed: 12/13/2022]
Abstract
We hypothesized that the free fatty acid receptors FFA1 and FFA4 might be involved in the anorectic response observed in fish after rising levels of long-chain fatty acids (LCFAs) such as oleate. In one experiment we demonstrated that intracerebroventricular (i.c.v.) treatment of rainbow trout with FFA1 and FFA4 agonists elicited an anorectic response 2, 6 and 24 h after treatment. In a second experiment, the same i.c.v. treatment resulted after 2 h in an enhancement in the mRNA abundance of anorexigenic neuropeptides pomca1 and cartpt and a decrease in the values of orexigenic peptides npy and agrp1 These changes occurred in parallel with those observed in the mRNA abundance and/or protein levels of the transcription factors Creb, Bsx and FoxO1, protein levels and phosphorylation status of Ampkα and Akt, and mRNA abundance of plcb1 and itrp3 Finally, we assessed in a third experiment the response of all these parameters after 2 h of i.c.v. treatment with oleate (the endogenous ligand of both free fatty acid receptors) alone or in the presence of FFA1 and FFA4 antagonists. Most effects of oleate disappeared in the presence of FFA1 and FFA4 antagonists. The evidence obtained supports the involvement of FFA1 and FFA4 in fatty acid sensing in fish brain, and thus involvement in food intake regulation through mechanisms not exactly comparable (differential response of neuropeptides and cellular signalling) to those known in mammals.
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Affiliation(s)
- Cristina Velasco
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
| | - Marta Conde-Sieira
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
| | - Sara Comesaña
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
| | - Mauro Chivite
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
| | - Adrián Díaz-Rúa
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
| | - Jesús M Míguez
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
| | - José L Soengas
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
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Lee SJ, Krieger JP, Vergara M, Quinn D, McDougle M, de Araujo A, Darling R, Zollinger B, Anderson S, Pan A, Simonnet EJ, Pignalosa A, Arnold M, Singh A, Langhans W, Raybould HE, de Lartigue G. Blunted Vagal Cocaine- and Amphetamine-Regulated Transcript Promotes Hyperphagia and Weight Gain. Cell Rep 2020; 30:2028-2039.e4. [PMID: 32049029 PMCID: PMC7063787 DOI: 10.1016/j.celrep.2020.01.045] [Citation(s) in RCA: 25] [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: 08/20/2019] [Revised: 12/06/2019] [Accepted: 01/15/2020] [Indexed: 12/31/2022] Open
Abstract
The vagus nerve conveys gastrointestinal cues to the brain to control eating behavior. In obesity, vagally mediated gut-brain signaling is disrupted. Here, we show that the cocaine- and amphetamine-regulated transcript (CART) is a neuropeptide synthesized proportional to the food consumed in vagal afferent neurons (VANs) of chow-fed rats. CART injection into the nucleus tractus solitarii (NTS), the site of vagal afferent central termination, reduces food intake. Conversely, blocking endogenous CART action in the NTS increases food intake in chow-fed rats, and this requires intact VANs. Viral-mediated Cartpt knockdown in VANs increases weight gain and daily food intake via larger meals and faster ingestion rate. In obese rats fed a high-fat, high-sugar diet, meal-induced CART synthesis in VANs is blunted and CART antibody fails to increase food intake. However, CART injection into the NTS retains its anorexigenic effect in obese rats. Restoring disrupted VAN CART signaling in obesity could be a promising therapeutic approach.
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Affiliation(s)
- Shin J Lee
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - Jean-Philippe Krieger
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland; Department of Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Macarena Vergara
- Department of Pharmacodynamics, Center for Integrative Cardiovascular and Metabolic Disease, University of Florida, Gainesville, FL, USA
| | | | - Molly McDougle
- Department of Pharmacodynamics, Center for Integrative Cardiovascular and Metabolic Disease, University of Florida, Gainesville, FL, USA; The John B. Pierce Laboratory, New Haven, CT, USA
| | - Alan de Araujo
- Department of Pharmacodynamics, Center for Integrative Cardiovascular and Metabolic Disease, University of Florida, Gainesville, FL, USA; The John B. Pierce Laboratory, New Haven, CT, USA; Yale University, New Haven, CT, USA
| | - Rebecca Darling
- Anatomy, Physiology and Cell Biology Department School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Benjamin Zollinger
- The John B. Pierce Laboratory, New Haven, CT, USA; Yale University, New Haven, CT, USA
| | - Seth Anderson
- The John B. Pierce Laboratory, New Haven, CT, USA; Yale University, New Haven, CT, USA
| | - Annabeth Pan
- The John B. Pierce Laboratory, New Haven, CT, USA; Yale University, New Haven, CT, USA
| | - Emilie J Simonnet
- Anatomy, Physiology and Cell Biology Department School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Angelica Pignalosa
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - Myrtha Arnold
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - Arashdeep Singh
- Department of Pharmacodynamics, Center for Integrative Cardiovascular and Metabolic Disease, University of Florida, Gainesville, FL, USA
| | - Wolfgang Langhans
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - Helen E Raybould
- Anatomy, Physiology and Cell Biology Department School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Guillaume de Lartigue
- Department of Pharmacodynamics, Center for Integrative Cardiovascular and Metabolic Disease, University of Florida, Gainesville, FL, USA; The John B. Pierce Laboratory, New Haven, CT, USA; Yale University, New Haven, CT, USA.
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11
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Hernández-Cáceres MP, Toledo-Valenzuela L, Díaz-Castro F, Ávalos Y, Burgos P, Narro C, Peña-Oyarzun D, Espinoza-Caicedo J, Cifuentes-Araneda F, Navarro-Aguad F, Riquelme C, Troncoso R, Criollo A, Morselli E. Palmitic Acid Reduces the Autophagic Flux and Insulin Sensitivity Through the Activation of the Free Fatty Acid Receptor 1 (FFAR1) in the Hypothalamic Neuronal Cell Line N43/5. Front Endocrinol (Lausanne) 2019; 10:176. [PMID: 30972025 PMCID: PMC6446982 DOI: 10.3389/fendo.2019.00176] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 03/01/2019] [Indexed: 12/13/2022] Open
Abstract
Chronic consumption of high fat diets (HFDs), rich in saturated fatty acids (SatFAs) like palmitic acid (PA), is associated with the development of obesity and obesity-related metabolic diseases such as type II diabetes mellitus (T2DM). Previous studies indicate that PA accumulates in the hypothalamus following consumption of HFDs; in addition, HFDs consumption inhibits autophagy and reduces insulin sensitivity. Whether malfunction of autophagy specifically in hypothalamic neurons decreases insulin sensitivity remains unknown. PA does activate the Free Fatty Acid Receptor 1 (FFAR1), also known as G protein-coupled receptor 40 (GPR40); however, whether FFAR1 mediates the effects of PA on hypothalamic autophagy and insulin sensitivity has not been shown. Here, we demonstrate that exposure to PA inhibits the autophagic flux and reduces insulin sensitivity in a cellular model of hypothalamic neurons (N43/5 cells). Furthermore, we show that inhibition of autophagy and the autophagic flux reduces insulin sensitivity in hypothalamic neuronal cells. Interestingly, the inhibition of the autophagic flux, and the reduction in insulin sensitivity are prevented by pharmacological inhibition of FFAR1. Our findings show that dysregulation of autophagy reduces insulin sensitivity in hypothalamic neuronal cells. In addition, our data suggest FFAR1 mediates the ability of PA to inhibit autophagic flux and reduce insulin sensitivity in hypothalamic neuronal cells. These results reveal a novel cellular mechanism linking PA-rich diets to decreased insulin sensitivity in the hypothalamus and suggest that hypothalamic autophagy might represent a target for future T2DM therapies.
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Affiliation(s)
- María Paz Hernández-Cáceres
- Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Autophagy Research Center, Santiago, Chile
| | - Lilian Toledo-Valenzuela
- Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Autophagy Research Center, Santiago, Chile
| | - Francisco Díaz-Castro
- Autophagy Research Center, Santiago, Chile
- Research Laboratory of Nutrition and Physical Activity, Institute of Nutrition and Food Technology, Universidad de Chile, Santiago, Chile
| | - Yenniffer Ávalos
- Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Autophagy Research Center, Santiago, Chile
| | - Paulina Burgos
- Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Autophagy Research Center, Santiago, Chile
| | - Carla Narro
- Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Autophagy Research Center, Santiago, Chile
| | - Daniel Peña-Oyarzun
- Autophagy Research Center, Santiago, Chile
- Advanced Center for Chronic Diseases and Center for Molecular Studies of the Cell, Universidad de Chile, Santiago, Chile
- Facultad de Odontología, Instituto de Investigación en Ciencias Odontológicas, Universidad de Chile, Santiago, Chile
| | - Jasson Espinoza-Caicedo
- Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Autophagy Research Center, Santiago, Chile
| | - Flavia Cifuentes-Araneda
- Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Autophagy Research Center, Santiago, Chile
| | - Fernanda Navarro-Aguad
- Laboratory of Differentiation and Pathology, Department of Cell and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Cecilia Riquelme
- Laboratory of Differentiation and Pathology, Department of Cell and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rodrigo Troncoso
- Autophagy Research Center, Santiago, Chile
- Research Laboratory of Nutrition and Physical Activity, Institute of Nutrition and Food Technology, Universidad de Chile, Santiago, Chile
- Advanced Center for Chronic Diseases and Center for Molecular Studies of the Cell, Universidad de Chile, Santiago, Chile
| | - Alfredo Criollo
- Autophagy Research Center, Santiago, Chile
- Advanced Center for Chronic Diseases and Center for Molecular Studies of the Cell, Universidad de Chile, Santiago, Chile
- Facultad de Odontología, Instituto de Investigación en Ciencias Odontológicas, Universidad de Chile, Santiago, Chile
| | - Eugenia Morselli
- Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Autophagy Research Center, Santiago, Chile
- *Correspondence: Eugenia Morselli
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12
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The role of fatty acids and their endocannabinoid-like derivatives in the molecular regulation of appetite. Mol Aspects Med 2018; 64:45-67. [DOI: 10.1016/j.mam.2018.01.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 01/05/2018] [Accepted: 01/07/2018] [Indexed: 02/07/2023]
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13
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The vagus neurometabolic interface and clinical disease. Int J Obes (Lond) 2018; 42:1101-1111. [PMID: 29795463 DOI: 10.1038/s41366-018-0086-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 03/07/2018] [Accepted: 03/12/2018] [Indexed: 01/07/2023]
Abstract
The nervous system both monitors and modulates body metabolism to maintain homoeostasis. In disease states such as obesity and diabetes, the neurometabolic interface is dysfunctional and contributes to clinical illness. The vagus nerve, in particular, with both sensory and motor fibres, provides an anatomical substrate for this interface. Its sensory fibres contain receptors for important circulating metabolic mediators, including leptin and cholecystokinin, and provide real-time information about these mediators to the central nervous system. In turn, efferent fibres within the vagus nerve participate in a brain-gut axis to regulate metabolism. In this review, we describe these vagus nerve-mediated metabolic pathways and recent clinical trials of vagus nerve stimulation for the management of obesity. These early studies suggest that neuromodulation approaches that employ electricity to tune neurometabolic circuits may represent a new tool in the clinical armamentarium directed against obesity.
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14
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Kim KS, Seeley RJ, Sandoval DA. Signalling from the periphery to the brain that regulates energy homeostasis. Nat Rev Neurosci 2018; 19:185-196. [PMID: 29467468 PMCID: PMC9190118 DOI: 10.1038/nrn.2018.8] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The CNS regulates body weight; however, we still lack a clear understanding of what drives decisions about when, how much and what to eat. A vast array of peripheral signals provides information to the CNS regarding fluctuations in energy status. The CNS then integrates this information to influence acute feeding behaviour and long-term energy homeostasis. Previous paradigms have delegated the control of long-term energy homeostasis to the hypothalamus and short-term changes in feeding behaviour to the hindbrain. However, recent studies have identified target hindbrain neurocircuitry that integrates the orchestration of individual bouts of ingestion with the long-term regulation of energy balance.
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Affiliation(s)
- Ki-Suk Kim
- Department of Surgery, University of Michigan Health System, Ann Arbor, MI, USA
| | - Randy J. Seeley
- Department of Surgery, University of Michigan Health System, Ann Arbor, MI, USA
| | - Darleen A. Sandoval
- Department of Surgery, University of Michigan Health System, Ann Arbor, MI, USA
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15
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Palmitic Acid-BSA enhances Amyloid-β production through GPR40-mediated dual pathways in neuronal cells: Involvement of the Akt/mTOR/HIF-1α and Akt/NF-κB pathways. Sci Rep 2017; 7:4335. [PMID: 28659580 PMCID: PMC5489526 DOI: 10.1038/s41598-017-04175-w] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 05/10/2017] [Indexed: 12/14/2022] Open
Abstract
The pathophysiological actions of fatty acids (FAs) on Alzheimer’s disease (AD), which are possibly mediated by genomic effects, are widely known; however, their non-genomic actions remain elusive. The aim of this study was to investigate the non-genomic mechanism of extra-cellular palmitic acid (PA) regulating beta-amyloid peptide (Aβ) production, which may provide a link between obesity and the occurrence of AD. In an obese mouse model, a high-fat diet (HFD) significantly increased the expression levels of APP and BACE1 as well as the AD pathology in the mouse brain. We further found that PA conjugated with bovine serum albumin (PA-BSA) increased the expression of APP and BACE1 and the production of Aβ through the G protein-coupled receptor 40 (GPR40) in SK-N-MC cells. PA-BSA coupling with GPR40 significantly induced Akt activation which is required for mTOR/p70S6K1-mediated HIF-1α expression and NF-κB phosphorylation facilitating the transcriptional activity of the APP and BACE1 genes. In addition, silencing of APP and BACE1 expression significantly decreased the production of Aβ in SK-N-MC cells treated with PA-BSA. In conclusion, these results show that extra-cellular PA coupled with GPR40 induces the expression of APP and BACE1 to facilitate Aβ production via the Akt-mTOR-HIF-1α and Akt-NF-κB pathways in SK-N-MC cells.
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16
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Hamilton MK, Raybould HE. Bugs, guts and brains, and the regulation of food intake and body weight. INTERNATIONAL JOURNAL OF OBESITY SUPPLEMENTS 2016; 6:S8-S14. [PMID: 28685024 DOI: 10.1038/ijosup.2016.3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The microbiota-gut-brain axis is currently being explored in many types of rodent models, including models of behavioral, neurodegenerative and metabolic disorders. Our laboratory is interested in determining the mechanisms and consequences of activation of vagal afferent neurons that lead to activation of parasympathetic reflexes and changes in feeding behavior in the context of obesity. Obesity is associated with microbial dysbiosis, decreased intestinal barrier function, gut inflammation, metabolic endotoxemia, chronic low-grade systemic inflammation and desensitization of vagal afferent nerves. This review will present the evidence that altered gut microbiota together with decreased gut barrier function allows the passage of bacterial components or metabolites in obese individuals, leading to the disruption of vagal afferent signaling and consequently resulting in an increase in body weight. We first review the most recent descriptions of gut microbial dysbiosis due to a high fat diet and describe changes in the gut barrier and the evidence of increased intestinal permeability in obesity. We then will review the evidence to show how manipulating the gut microbiota via pre and probiotics can restore gut barrier function and prevent weight gain. Lastly, we present possible mechanisms by which the microbe-gut-brain axis may have a role in obesity. The studies mentioned in this review have provided new targets to treat and prevent obesity and have highlighted how the microbiota-gut-brain axis is involved.
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Affiliation(s)
- M K Hamilton
- Department of Anatomy, Physiology and Cell Biology, UC Davis School of Veterinary Medicine, Davis, CA, USA
| | - H E Raybould
- Department of Anatomy, Physiology and Cell Biology, UC Davis School of Veterinary Medicine, Davis, CA, USA
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17
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de Lartigue G, Diepenbroek C. Novel developments in vagal afferent nutrient sensing and its role in energy homeostasis. Curr Opin Pharmacol 2016; 31:38-43. [PMID: 27591963 DOI: 10.1016/j.coph.2016.08.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 07/01/2016] [Accepted: 08/11/2016] [Indexed: 12/16/2022]
Abstract
Vagal afferent neurons (VANs) play an important role in the control of food intake by signaling nutrient type and quantity to the brain. Recent findings are broadening our view of how VANs impact not only food intake but also energy homeostasis. This review focuses exclusively on studies of the vagus nerve from the past 2 years that highlight major new advancements in the field. We firstly discuss evidence that VANs can directly sense nutrients, and we consider new insights into mechanisms affecting sensing of gastric distension and signaling by gastrointestinal hormones ghrelin and GLP1. We discuss evidence that disrupting vagal afferent signaling increases long-term control of food intake and body weight management, and the importance of this gut-brain pathway in mediating beneficial effects of bariatric surgery. We conclude by highlighting novel roles for vagal afferent neurons in circadian rhythm, thermogenesis, and reward that may provide insight into mechanisms by which VAN nutrient sensing controls long-term control of energy homeostasis.
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Affiliation(s)
- Guillaume de Lartigue
- The John B. Pierce Laboratory, New Haven, CT, USA; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA.
| | - Charlene Diepenbroek
- The John B. Pierce Laboratory, New Haven, CT, USA; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
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18
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Li AJ, Wiater MF, Wang Q, Wank S, Ritter S. Deletion of GPR40 fatty acid receptor gene in mice blocks mercaptoacetate-induced feeding. Am J Physiol Regul Integr Comp Physiol 2016; 310:R968-74. [PMID: 26984894 DOI: 10.1152/ajpregu.00548.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 03/10/2016] [Indexed: 12/12/2022]
Abstract
Both increased and decreased fatty acid (FA) availability contribute to control of food intake. For example, it is well documented that intestinal FA reduces feeding by triggering enterondocrine secretion of satietogenic peptides, such as cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1). In contrast, mechanisms by which decreased FA availability increase feeding are not well understood. Over the past three decades substantial research related to FA availability and increased feeding has involved use of the orexigenic compound mercaptoacetate (MA). Because MA reportedly inhibits FA oxidation, it has been assumed that reduced FA oxidation accounts for the orexigenic action of MA. Recently, however, we demonstrated that MA antagonizes G protein-coupled receptor 40 (GPR40), a membrane receptor for long and medium chain FA. We also demonstrated that, by antagonizing GPR40, MA inhibits GLP-1 secretion and attenuates vagal afferent activation by FA. Because both vagal afferent activation and GLP-1 inhibit food intake, we postulated that inhibition of GPR40 by MA might underlie the orexigenic action of MA. We tested this hypothesis using male and female GPR40 knockout (KO) and wild-type (WT) mice. Using several testing protocols, we found that MA increased feeding in WT, but not GPR40 KO mice, and that GPR40 KO mice gained more weight than WT on a high-fat diet. Metabolic monitoring after MA or saline injection in the absence of food did not reveal significant differences in respiratory quotient or energy expenditure between treatment groups or genotypes. These results support the hypothesis that MA stimulates food intake by blocking FA effects on GPR40.
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Affiliation(s)
- Ai-Jun Li
- Programs in Neuroscience, Washington State University, Pullman, Washington; and
| | - Michael F Wiater
- Programs in Neuroscience, Washington State University, Pullman, Washington; and
| | - Qing Wang
- Programs in Neuroscience, Washington State University, Pullman, Washington; and
| | - Stephen Wank
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland
| | - Sue Ritter
- Programs in Neuroscience, Washington State University, Pullman, Washington; and
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19
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Li AJ, Wang Q, Dinh TT, Simasko SM, Ritter S. Mercaptoacetate blocks fatty acid-induced GLP-1 secretion in male rats by directly antagonizing GPR40 fatty acid receptors. Am J Physiol Regul Integr Comp Physiol 2016; 310:R724-32. [PMID: 26791830 DOI: 10.1152/ajpregu.00387.2015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 01/19/2016] [Indexed: 12/13/2022]
Abstract
Mercaptoacetate (MA) is an orexigenic agent reported to block fatty acid (FA) oxidation. Recently, however, we reported evidence from isolated nodose ganglion neurons that MA antagonizes the G protein-coupled long- and medium-chain FA receptor GPR40. GPR40 mediates FA-induced secretion of the satietogenic incretin peptide glucagon-like peptide 1 (GLP-1), by enteroendocrine L cells, as well as FA-induced enhancement of glucose-stimulated insulin secretion. Our results in cultured nodose neurons suggest that MA would also block GPR40 in enteroendocrine cells controlling GLP-1 secretion. If so, this would suggest an alternative mechanism by which MA increases food intake. We tested the hypothesis that MA blocks FA-induced GLP-1 secretion in vitro using cultured STC-1 cells (a murine enteroendocrine cell line) and in vivo in adult male rats. In vitro, MA blocked the increase in both cytosolic Ca(2+)and GLP-1 release stimulated by FAs and also reduced (but less effectively) the response of STC-1 cells to grifolic acid, a partial agonist of the GPR120 FA receptor. In vivo, MA reduced GLP-1 secretion following olive oil gavage while also increasing glucose and decreasing insulin levels. The carnitine palmatoyltransferase 1 antagonist etomoxir did not alter these responses. Results indicate that MA's actions, including its orexigenic effect, are mediated by GPR40 (and possibly GPR120) receptor antagonism and not by blockade of fat oxidation, as previously believed. Analysis of MA's interaction with GPR40 may facilitate understanding of the multiple functions of this receptor and the manner in which FAs participate in the control of hunger and satiety.
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Affiliation(s)
- Ai-Jun Li
- Programs in Neuroscience, Washington State University, Pullman, Washington
| | - Qing Wang
- Programs in Neuroscience, Washington State University, Pullman, Washington
| | - Thu T Dinh
- Programs in Neuroscience, Washington State University, Pullman, Washington
| | - Steve M Simasko
- Programs in Neuroscience, Washington State University, Pullman, Washington
| | - Sue Ritter
- Programs in Neuroscience, Washington State University, Pullman, Washington
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20
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Duca FA, Bauer PV, Hamr SC, Lam TKT. Glucoregulatory Relevance of Small Intestinal Nutrient Sensing in Physiology, Bariatric Surgery, and Pharmacology. Cell Metab 2015. [PMID: 26212718 DOI: 10.1016/j.cmet.2015.07.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Emerging evidence suggests the gastrointestinal tract plays an important glucoregulatory role. In this perspective, we first review how the intestine senses ingested nutrients, initiating crucial negative feedback mechanisms through a gut-brain neuronal axis to regulate glycemia, mainly via reduction in hepatic glucose production. We then highlight how intestinal energy sensory mechanisms are responsible for the glucose-lowering effects of bariatric surgery, specifically duodenal-jejunal bypass, and the antidiabetic agents metformin and resveratrol. A better understanding of these pathways lays the groundwork for intestinally targeted drug therapy for the treatment of diabetes.
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Affiliation(s)
- Frank A Duca
- Toronto General Research Institute and Department of Medicine, UHN, Toronto, ON M5G 1L7, Canada
| | - Paige V Bauer
- Toronto General Research Institute and Department of Medicine, UHN, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Sophie C Hamr
- Toronto General Research Institute and Department of Medicine, UHN, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Tony K T Lam
- Toronto General Research Institute and Department of Medicine, UHN, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G 2C4, Canada.
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21
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Li AJ, Wang Q, Elsarelli MM, Brown RL, Ritter S. Hindbrain Catecholamine Neurons Activate Orexin Neurons During Systemic Glucoprivation in Male Rats. Endocrinology 2015; 156:2807-20. [PMID: 25978516 PMCID: PMC5393341 DOI: 10.1210/en.2015-1138] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Hindbrain catecholamine neurons are required for elicitation of feeding responses to glucose deficit, but the forebrain circuitry required for these responses is incompletely understood. Here we examined interactions of catecholamine and orexin neurons in eliciting glucoprivic feeding. Orexin neurons, located in the perifornical lateral hypothalamus (PeFLH), are heavily innervated by hindbrain catecholamine neurons, stimulate food intake, and increase arousal and behavioral activation. Orexin neurons may therefore contribute importantly to appetitive responses, such as food seeking, during glucoprivation. Retrograde tracing results showed that nearly all innervation of the PeFLH from the hindbrain originated from catecholamine neurons and some raphe nuclei. Results also suggested that many catecholamine neurons project collaterally to the PeFLH and paraventricular hypothalamic nucleus. Systemic administration of the antiglycolytic agent, 2-deoxy-D-glucose, increased food intake and c-Fos expression in orexin neurons. Both responses were eliminated by a lesion of catecholamine neurons innervating orexin neurons using the retrogradely transported immunotoxin, anti-dopamine-β-hydroxylase saporin, which is specifically internalized by dopamine-β-hydroxylase-expressing catecholamine neurons. Using designer receptors exclusively activated by designer drugs in transgenic rats expressing Cre recombinase under the control of tyrosine hydroxylase promoter, catecholamine neurons in cell groups A1 and C1 of the ventrolateral medulla were activated selectively by peripheral injection of clozapine-N-oxide. Clozapine-N-oxide injection increased food intake and c-Fos expression in PeFLH orexin neurons as well as in paraventricular hypothalamic nucleus neurons. In summary, catecholamine neurons are required for the activation of orexin neurons during glucoprivation. Activation of orexin neurons may contribute to appetitive responses required for glucoprivic feeding.
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Affiliation(s)
- Ai-Jun Li
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - Qing Wang
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - Megan M Elsarelli
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - R Lane Brown
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - Sue Ritter
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
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22
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Mansouri A, Pacheco-López G, Ramachandran D, Arnold M, Leitner C, Prip-Buus C, Langhans W, Morral N. Enhancing hepatic mitochondrial fatty acid oxidation stimulates eating in food-deprived mice. Am J Physiol Regul Integr Comp Physiol 2014; 308:R131-7. [PMID: 25427767 DOI: 10.1152/ajpregu.00279.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hepatic fatty acid oxidation (FAO) has long been implicated in the control of eating. Nevertheless, direct evidence for a causal relationship between changes in hepatic FAO and changes in food intake is still missing. Here we tested whether increasing hepatic FAO via adenovirus-mediated expression of a mutated form of the key regulatory enzyme of mitochondrial FAO carnitine palmitoyltransferase 1A (CPT1mt), which is active but insensitive to inhibition by malonyl-CoA, affects eating and metabolism in mice. CPT1mt expression increased hepatocellular CPT1 protein levels. This resulted in an increase in circulating ketone body levels in fasted CPT1mt-expressing mice, suggesting an increase in hepatic FAO. These mice did not show any significant changes in cumulative food intake, energy expenditure, or respiratory quotient after 4-h food deprivation. After 24-h food deprivation, however, the CPT1mt-expressing mice displayed increased food intake. Thus expression of CPT1mt in the liver increases hepatic FAO capacity, but does not inhibit eating. Rather, it may even stimulate eating after prolonged food deprivation. These data do not support the hypothesis that an increase in hepatic FAO decreases food intake.
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Affiliation(s)
- Abdelhak Mansouri
- Physiology and Behavior Laboratory, Institute of Food, Nutrition, and Health, ETH Zurich, Switzerland
| | - Gustavo Pacheco-López
- Physiology and Behavior Laboratory, Institute of Food, Nutrition, and Health, ETH Zurich, Switzerland
| | - Deepti Ramachandran
- Physiology and Behavior Laboratory, Institute of Food, Nutrition, and Health, ETH Zurich, Switzerland
| | - Myrtha Arnold
- Physiology and Behavior Laboratory, Institute of Food, Nutrition, and Health, ETH Zurich, Switzerland
| | - Claudia Leitner
- Physiology and Behavior Laboratory, Institute of Food, Nutrition, and Health, ETH Zurich, Switzerland
| | - Carina Prip-Buus
- INSERM, U1016, Institut Cochin, Paris, France; CNRS, UMR8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine Paris, France; and
| | - Wolfgang Langhans
- Physiology and Behavior Laboratory, Institute of Food, Nutrition, and Health, ETH Zurich, Switzerland
| | - Núria Morral
- Department of Medical and Molecular Genetics, and Center for Diabetes Research, Indiana University School of Medicine, Indianapolis, Indiana
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23
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Duca FA, Yue JTY. Fatty acid sensing in the gut and the hypothalamus: in vivo and in vitro perspectives. Mol Cell Endocrinol 2014; 397:23-33. [PMID: 25261798 DOI: 10.1016/j.mce.2014.09.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 09/19/2014] [Accepted: 09/19/2014] [Indexed: 12/15/2022]
Abstract
The ability to properly sense both ingested and circulating nutrients is crucial for the maintenance of metabolic homeostasis. As such, both the gastrointestinal tract and the hypothalamus have demonstrated the capacity to sense and effectively respond to nutrients, such as fatty acids, to control food intake and glucose production to regulate energy and glucose homeostasis. In modern, Westernized societies, obesity and diabetes rates continue to rise unabated, due in part to an increase in highly palatable high-fat diet consumption. Thus, our understanding in the ability of the body to successfully monitor lipids is more vital than ever. This review details the current understanding of both the gut and the brain, specifically the hypothalamus, in sensing fatty acids. Highlighting both in vivo and in vitro studies, we explore some of the mechanisms upon which different fatty acids activate enteroendocrine and neural lipid-sensing signaling mechanisms to subsequently lower food intake and glucose production to ultimately regulate metabolic homeostasis. A better understanding of these lipid-sensing pathways could lay the groundwork for successful pharmacological targets for the treatment of obesity and diabetes.
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Affiliation(s)
- Frank A Duca
- Toronto General Research Institute and Department of Medicine, UHN, Toronto, M5G 1L7, Canada
| | - Jessica T Y Yue
- Toronto General Research Institute and Department of Medicine, UHN, Toronto, M5G 1L7, Canada.
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