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Klingbeil EA, Schade R, Lee SH, Kirkland R, de La Serre CB. Manipulation of feeding patterns in high fat diet fed rats improves microbiota composition dynamics, inflammation and gut-brain signaling. Physiol Behav 2024:114643. [PMID: 39059597 DOI: 10.1016/j.physbeh.2024.114643] [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: 03/07/2024] [Revised: 06/29/2024] [Accepted: 07/18/2024] [Indexed: 07/28/2024]
Abstract
Chronic consumption of high fat (HF) diets has been shown to increase meal size and meal frequency in rodents, resulting in overeating. Reducing meal frequency and establishing periods of fasting, independently of caloric intake, may improve obesity-associated metabolic disorders. Additionally, diet-driven changes in microbiota composition have been shown to play a critical role in the development and maintenance of metabolic disorders. In this study, we used a pair-feeding paradigm to reduce meal frequency and snacking episodes while maintaining overall intake and body weight in HF fed rats. We hypothesized that manipulation of feeding patterns would improve microbiota composition and metabolic outcomes. Male Wistar rats were placed in three groups consuming either a HF, low fat diet (LF, matched for sugar), or pair-fed HF diet for 7 weeks (n=11-12/group). Pair-fed animals received the same amount of food consumed by the HF fed group once daily before dark onset (HF-PF). Rats underwent oral glucose tolerance and gut peptide cholecystokinin sensitivity tests. Bacterial DNA was extracted from the feces collected during both dark and light cycles and sequenced via Illumina MiSeq sequencing of the 16S V4 region. Our pair-feeding paradigm reduced meal numbers, especially small meals in the inactive phase, without changing total caloric intake. This shift in feeding patterns reduced relative abundances of obesity-associated bacteria and maintained circadian fluctuations in microbial abundances. These changes were associated with improved gastrointestinal (GI) function, reduced inflammation, and improved glucose tolerance and gut to brain signaling. We concluded from these data that targeting snacking may help improve metabolic outcomes, independently of energy content of the diet and hyperphagia.
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Affiliation(s)
- E A Klingbeil
- Department of Nutritional Sciences, The University of Texas at Austin
| | - R Schade
- Department of Microbiology and Immunology, Stanford University School of Medicine
| | - S H Lee
- Department of Food Sciences, Sun Moon University, South Korea
| | - R Kirkland
- Office of Research, University of Georgia
| | - C B de La Serre
- Department of Nutritional Sciences, University of Georgia; Department of Biomedical Sciences, Colorado State University..
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2
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Minaya DM, Kim JS, Kirkland R, Allen J, Cullinan S, Maclang N, de Lartigue G, de La Serre CB. Transfer with microbiota from lean donors prevents excessive weight gain and restores gut-brain vagal signaling in obese rats maintained on a high fat diet. RESEARCH SQUARE 2024:rs.3.rs-4438240. [PMID: 38853960 PMCID: PMC11160927 DOI: 10.21203/rs.3.rs-4438240/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Background The collection of microorganisms, mainly bacteria, which live in the gastrointestinal (GI) tract are collectible known as the gut microbiota. GI bacteria play an active role in regulation of the host's immune system and metabolism, as well as certain pathophysiological processes. Diet is the main factor modulating GI microbiota composition and recent studies have shown that high fat (HF) diets induce detrimental changes, known as dysbiosis, in the GI bacterial makeup. HF diet induced microbiota dysbiosis has been associated with structural and functional changes in gut-brain vagally mediated signaling system, associated with overeating and obesity. Although HF-driven changes in microbiota composition are sufficient to alter vagal signaling, it is unknown if restoring normal microbiota in obesity can improve gut-brain signaling and metabolic outcomes. In this study, we evaluated the effect of lean gut microbiota transfer in obese, vagally compromised, rats on gut-brain communication, food intake, and body weight. Male Sprague-Dawley rats were maintained on regular chow, or 45% HF diet for nine weeks followed by three weeks of microbiota depletion using an antibiotic cocktail. The animals were then divided into four groups (n=10 each): LF - control group on regular chow, LF-LF - chow fed animals that received antibiotics and microbiota from chow fed animals, HF-LF - HF fed animals that received microbiota from chow fed animals, and HF-HF - HF fed animals that received microbiota from HF fed animals. Animals were gavaged with donor microbiota for three consecutive days on week one and once a week thereafter for three more weeks. HF-LF animals received inulin as a prebiotic to aid the establishment of the lean microbiome. Results We found that transferring a LF microbiota to HF fed animals (HF-LF) reduced caloric intake during the light phase when compared with HF-HF rats and prevented additional excessive weight gain. We did not observe significant changes in the density of vagal afferents terminating in the brainstem among the groups, however, HF-LF animals displayed an increase in postprandial activation of both primary sensory neurons innervating the GI tract and brainstem secondary neurons. Conclusions We concluded from these data that normalizing microbiota composition in obese rats improves gut-brain communication and restores normal feeding patterns which was associated with a reduction in weight gain.
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Affiliation(s)
- Dulce M. Minaya
- Department of Nutritional Science, University of Georgia, Athens, GA
| | | | - Rebecca Kirkland
- Department of Nutritional Science, University of Georgia, Athens, GA
| | - Jillian Allen
- Department of Nutritional Science, University of Georgia, Athens, GA
| | - Sitara Cullinan
- Department of Nutritional Science, University of Georgia, Athens, GA
| | - Neil Maclang
- Department of Nutritional Science, University of Georgia, Athens, GA
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3
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Berthoud HR. Reduced postabsorptive interoception of nutrients in obesity: cause or consequence? Am J Clin Nutr 2023; 118:496-497. [PMID: 37661103 DOI: 10.1016/j.ajcnut.2023.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 07/15/2023] [Indexed: 09/05/2023] Open
Affiliation(s)
- Hans-Rudolf Berthoud
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, United States.
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Hamamah S, Amin A, Al-Kassir AL, Chuang J, Covasa M. Dietary Fat Modulation of Gut Microbiota and Impact on Regulatory Pathways Controlling Food Intake. Nutrients 2023; 15:3365. [PMID: 37571301 PMCID: PMC10421457 DOI: 10.3390/nu15153365] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 07/24/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
Obesity is a multifactorial disease that continues to increase in prevalence worldwide. Emerging evidence has shown that the development of obesity may be influenced by taxonomic shifts in gut microbiota in response to the consumption of dietary fats. Further, these alterations in gut microbiota have been shown to promote important changes in satiation signals including gut hormones (leptin, ghrelin, GLP-1, peptide YY and CCK) and orexigenic and anorexigenic neuropeptides (AgRP, NPY, POMC, CART) that influence hyperphagia and therefore obesity. In this review, we highlight mechanisms by which gut microbiota can influence these satiation signals both locally in the gastrointestinal tract and via microbiota-gut-brain communication. Then, we describe the effects of dietary interventions and associated changes in gut microbiota on satiety signals through microbiota-dependent mechanisms. Lastly, we present microbiota optimizing therapies including prebiotics, probiotics, synbiotics and weight loss surgery that can help restore beneficial gut microbiota by enhancing satiety signals to reduce hyperphagia and subsequent obesity. Overall, a better understanding of the mechanisms by which dietary fats induce taxonomical shifts in gut microbiota and their impact on satiation signaling pathways will help develop more targeted therapeutic interventions in delaying the onset of obesity and in furthering its treatment.
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Affiliation(s)
- Sevag Hamamah
- Department of Basic Medical Sciences, Western University of Health Sciences, College of Osteopathic Medicine, Pomona, CA 91766, USA; (S.H.); (A.A.); (A.L.A.-K.); (J.C.)
| | - Arman Amin
- Department of Basic Medical Sciences, Western University of Health Sciences, College of Osteopathic Medicine, Pomona, CA 91766, USA; (S.H.); (A.A.); (A.L.A.-K.); (J.C.)
| | - Abdul Latif Al-Kassir
- Department of Basic Medical Sciences, Western University of Health Sciences, College of Osteopathic Medicine, Pomona, CA 91766, USA; (S.H.); (A.A.); (A.L.A.-K.); (J.C.)
| | - Judith Chuang
- Department of Basic Medical Sciences, Western University of Health Sciences, College of Osteopathic Medicine, Pomona, CA 91766, USA; (S.H.); (A.A.); (A.L.A.-K.); (J.C.)
| | - Mihai Covasa
- Department of Basic Medical Sciences, Western University of Health Sciences, College of Osteopathic Medicine, Pomona, CA 91766, USA; (S.H.); (A.A.); (A.L.A.-K.); (J.C.)
- Department of Biomedical Sciences, College of Medicine and Biological Science, University of Suceava, 720229 Suceava, Romania
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Pan X, Zhang M, Tian A, Chen L, Sun Z, Wang L, Chen P. Exploring the genetic correlation between obesity-related traits and regional brain volumes: Evidence from UK Biobank cohort. Neuroimage Clin 2022; 33:102870. [PMID: 34872017 PMCID: PMC8648807 DOI: 10.1016/j.nicl.2021.102870] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 10/27/2021] [Accepted: 10/28/2021] [Indexed: 01/21/2023]
Abstract
OBJECTIVE To determine whether there is a correlation between obesity-related variants and regional brain volumes. METHODS Based on a mixed linear model (MLM), we analyzed the association between 1,498 obesity-related SNPs in the GWAS Catalog and 164 regional brain volumes from 29,420 participants (discovery cohort N = 19,997, validation cohort N = 9,423) in UK Biobank. The statistically significant brain regions in association analysis were classified into 6 major neural networks (dopamine (DA) motive system, central autonomic network (CAN), cognitive emotion regulation, visual object recognition network, auditory object recognition network, and sensorimotor system). We summarized the association between obesity-related variants (metabolically healthy obesity variants, metabolically unhealthy obesity variants, and unclassified obesity-related variants) and neural networks. RESULTS From association analysis, we determined that 17 obesity-related SNPs were associated with 51 regional brain volumes. Several single SNPs (e.g., rs13107325-T (SLC39A8), rs1876829-C (CRHR1), and rs1538170-T (CENPW)) were associated with multiple regional brain volumes. In addition, several single brain regions (e.g., the white matter, the grey matter in the putamen, subcallosal cortex, and insular cortex) were associated with multiple obesity-related variants. The metabolically healthy obesity variants were mainly associated with the regional brain volumes in the DA motive system, sensorimotor system and cognitive emotion regulation neural networks, while metabolically unhealthy obesity variants were mainly associated with regional brain volumes in the CAN and total tissue volumes. In addition, unclassified obesity-related variants were mainly associated with auditory object recognition network and total tissue volumes. The results of MeSH (medical subject headings) enrichment analysis showed that obesity genes associated with brain structure pointed to the functional relatedness with 5-Hydroxytryptamine receptor 4 (5-HT4), growth differentiation factor 5 (GDF5), and high mobility group protein AT-hook 2 (HMGA2 protein). CONCLUSION In summary, we found that obesity-related variants were associated with different brain volume measures. On the basis of the multiple SNPs, we found that metabolically healthy and unhealthy obesity-related SNPs were associated with different brain neural networks. Based on our enrichment analysis, modifications of the 5-HT4 pathway might be a promising therapeutic strategy for obesity.
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Affiliation(s)
- Xingchen Pan
- Department of Molecular Biology, College of Basic Medical Sciences, Jilin University, Changchun, Jilin, China; Department of Genetics, College of Basic Medical Sciences, Jilin University, Changchun, Jilin, China
| | - Miaoran Zhang
- Department of Pathology, College of Basic Medical Sciences, Jilin University, Changchun, Jilin, China
| | - Aowen Tian
- Department of Pathology, College of Basic Medical Sciences, Jilin University, Changchun, Jilin, China
| | - Lanlan Chen
- School of Clinical Medicine, Jilin University, Changchun, 130000, China
| | - Zewen Sun
- Department of Genetics, College of Basic Medical Sciences, Jilin University, Changchun, Jilin, China
| | - Liying Wang
- Department of Molecular Biology, College of Basic Medical Sciences, Jilin University, Changchun, Jilin, China.
| | - Peng Chen
- Department of Genetics, College of Basic Medical Sciences, Jilin University, Changchun, Jilin, China; Department of Pathology, College of Basic Medical Sciences, Jilin University, Changchun, Jilin, China.
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Rautmann AW, de La Serre CB. Microbiota's Role in Diet-Driven Alterations in Food Intake: Satiety, Energy Balance, and Reward. Nutrients 2021; 13:nu13093067. [PMID: 34578945 PMCID: PMC8470213 DOI: 10.3390/nu13093067] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 08/18/2021] [Accepted: 08/25/2021] [Indexed: 02/07/2023] Open
Abstract
The gut microbiota plays a key role in modulating host physiology and behavior, particularly feeding behavior and energy homeostasis. There is accumulating evidence demonstrating a role for gut microbiota in the etiology of obesity. In human and rodent studies, obesity and high-energy feeding are most consistently found to be associated with decreased bacterial diversity, changes in main phyla relative abundances and increased presence of pro-inflammatory products. Diet-associated alterations in microbiome composition are linked with weight gain, adiposity, and changes in ingestive behavior. There are multiple pathways through which the microbiome influences food intake. This review discusses these pathways, including peripheral mechanisms such as the regulation of gut satiety peptide release and alterations in leptin and cholecystokinin signaling along the vagus nerve, as well as central mechanisms, such as the modulation of hypothalamic neuroinflammation and alterations in reward signaling. Most research currently focuses on determining the role of the microbiome in the development of obesity and using microbiome manipulation to prevent diet-induced increase in food intake. More studies are necessary to determine whether microbiome manipulation after prolonged energy-dense diet exposure and obesity can reduce intake and promote meaningful weight loss.
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Yosten GLC, Haddock CJ, Harada CM, Almeida-Pereira G, Kolar GR, Stein LM, Hayes MR, Salvemini D, Samson WK. Past, present and future of cocaine- and amphetamine-regulated transcript peptide. Physiol Behav 2021; 235:113380. [PMID: 33705816 DOI: 10.1016/j.physbeh.2021.113380] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/22/2021] [Accepted: 03/01/2021] [Indexed: 01/02/2023]
Abstract
The existence of the peptide encoded by the cocaine- and amphetamine-regulated transcript (Cartpt) has been recognized since 1981, but it was not until 1995, that the gene encoding CART peptide (CART) was identified. With the availability of the predicted protein sequence of CART investigators were able to identify sites of peptide localization, which then led to numerous approaches attempting to clarify CART's multiple pharmacologic effects and even provide evidence of potential physiologic relevance. Although not without controversy, a picture emerged of the importance of CART in ingestive behaviors, reward behaviors and even pain sensation. Despite the wealth of data hinting at the significance of CART, in the absence of an identified receptor, the full potential for this peptide or its analogs to be developed into therapeutic agents remained unrealized. There was evidence favoring the action of CART via a G protein-coupled receptor (GPCR), but despite multiple attempts the identity of that receptor eluded investigators until recently. Now with the identification of the previously orphaned GPCR, GPR160, as a receptor for CART, focus on this pluripotent neuropeptide will in all likelihood experience a renaissance and the potential for the development of pharmcotherapies targeting GPR160 seems within reach.
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Affiliation(s)
- Gina L C Yosten
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA; Henry and Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Christopher J Haddock
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Caron M Harada
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA; Henry and Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Gislaine Almeida-Pereira
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Grant R Kolar
- Henry and Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, MO 63104, USA; Department of Pathology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Lauren M Stein
- Department of Psychiatry, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Matthew R Hayes
- Department of Psychiatry, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Daniela Salvemini
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA; Henry and Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Willis K Samson
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA; Henry and Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
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8
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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: 6.3] [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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9
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Kim JS, Kirkland RA, Lee SH, Cawthon CR, Rzepka KW, Minaya DM, de Lartigue G, Czaja K, de La Serre CB. Gut microbiota composition modulates inflammation and structure of the vagal afferent pathway. Physiol Behav 2020; 225:113082. [PMID: 32682966 DOI: 10.1016/j.physbeh.2020.113082] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 07/02/2020] [Accepted: 07/15/2020] [Indexed: 12/17/2022]
Abstract
Vagal afferent neurons (VAN), located in the nodose ganglion (NG) innervate the gut and terminate in the nucleus of solitary tract (NTS) in the brainstem. They are the primary sensory neurons integrating gut-derived signals to regulate meal size. Chronic high-fat diet (HFD) consumption impairs vagally mediated satiety, resulting in overfeeding. There is evidence that HFD consumption leads to alterations in both vagal nerve function and structural integrity. HFD also leads to marked gut microbiota dysbiosis; in rodent models, dysbiosis is sufficient to induce weight gain. In this study, we investigated the effect of microbiota dysbiosis on gut-brain vagal innervation independently of diet. To do so, we recolonized microbiota-depleted rats with gastrointestinal (GI) contents isolated from donor animals fed either a HFD (45 or 60% fat) or a low fat diet (LFD, 13% fat). We used two different depletion models while maintaining the animals on LFD: 1) conventionally raised Fischer and Wistar rats that underwent a depletion paradigm using an antibiotic cocktail and 2) germ free (GF) raised Fischer rats. Following recolonization, receiver animals were designated as ConvLF and ConvHF. Fecal samples were collected throughout these studies and analyzed via 16S Illumina sequencing. In both models, bacteria that were identified as characteristic of HFD were successfully transferred to recipient animals. Three weeks post-colonization, ConvHF rats showed significant increases in ionized calcium-binding adapter molecule-1 (Iba1) positive immune cells in the NG compared to ConvLF animals. Additionally, using isolectin B4 (IB4) staining to identify c-fibers, we found that, compared to ConvLF animals, ConvHF rats displayed decreased innervation at the level of the medial NTS; c-fibers at this level are believed to be primarily of vagal origin. This alteration in vagal structure was associated with a loss in satiety induced by the gut peptide cholecystokinin (CCK). Increased presence of immunocompetent Iba1+ cells along the gut-brain axis and alterations in NTS innervation were still evident in ConvHF rats compared to ConvLF animals 12 weeks post-colonization and were associated with increases in food intake and body weight (BW). We conclude from these data that microbiota dysbiosis can alter gut-brain vagal innervation, potentially via recruitment and/or activation of immune cells.
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Affiliation(s)
- J S Kim
- Dept. of Foods and Nutrition, USA
| | | | - S H Lee
- Dept. of Foods and Nutrition, USA
| | | | - K W Rzepka
- Dept. of Veterinary Biosciences and Diagnostic Imaging, University of Georgia, Athens, GA, USA
| | - D M Minaya
- Dept. of Veterinary Biosciences and Diagnostic Imaging, University of Georgia, Athens, GA, USA
| | - G de Lartigue
- Dept. of Pharmacodynamics, University of Florida, Gainesville, FL, USA
| | - K Czaja
- Dept. of Veterinary Biosciences and Diagnostic Imaging, University of Georgia, Athens, GA, USA
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10
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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: 18] [Impact Index Per Article: 4.5] [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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Li D, Tong Y, Li Y. Associations between dietary oleic acid and linoleic acid and depressive symptoms in perimenopausal women: The Study of Women's Health Across the Nation. Nutrition 2019; 71:110602. [PMID: 31837641 DOI: 10.1016/j.nut.2019.110602] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 08/24/2019] [Accepted: 10/05/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVES The aim of this study was to review the association of dietary intake of oleic and linoleic acids (OA and LA, respectively) with depressive symptoms in perimenopausal women. METHODS This cross-sectional study used data from the Study of Women's Health Across the Nation (SWAN). Linear and logistic regressions and restricted cubic spline models were performed to examine the association of intake of OA and LA with depression. RESULTS We included 2793 women 42 to 52 y of age in the present study. Intake of the two acids was positively associated with the Center for Epidemiologic Studies Depression Scale (CES-D) scores in unadjusted and age-, race/ethnicity-, total family income- and education-adjusted linear regression model. The fully adjusted regression coefficients were β = 0.089 and β = 0.145 for oleic and linoleic acid intake, respectively. OA and LA intake was positively associated with depressive symptoms (CES-D score ≥16) in unadjusted and age-, race/ethnicity-, total family income- and education-adjusted logistic regression model. The fully adjusted odds ratios (ORs) with 95% confidence intervals (CIs) of depressive symptoms were 1.994 (1.298-3.063) and 1.592 (1.047-2.421) for the highest versus lowest quartile of intake of OA and LA, respectively. CONCLUSION Intake of OA and LA may be positively associated with depressive symptoms in perimenopausal women.
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Affiliation(s)
- Di Li
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan, China.
| | - Yongqing Tong
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yan Li
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan, China.
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12
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Karras SN, Koufakis T, Mustafa OG, Kotsa K. Anti-incretin effect: The other face of Janus in human glucose homeostasis. Obes Rev 2019; 20:1597-1607. [PMID: 31347774 DOI: 10.1111/obr.12917] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/26/2019] [Accepted: 07/02/2019] [Indexed: 02/06/2023]
Abstract
The provocative idea that type 2 diabetes (T2D) may be a surgically treated disorder is based on accumulating evidence suggesting impressive remission rates of obesity and diabetes following bariatric surgery interventions. According to the "anti-incretin" theory, ingestion of food in the gastrointestinal (GI) tract, apart from activating the well-described incretin effect, also results in the parallel stimulation of a series of negative feedback mechanisms (anti-incretin effect). The primary goal of these regulations is to counteract the effects of incretins and other postprandial glucose-lowering adaptive mechanisms. Disruption of the equilibrium between incretins and anti-incretins could be an additional pathway leading to the development of insulin resistance and hyperglycemia. This theory provides an alternative theoretical framework to explain the mechanisms behind the optimal effects of metabolic surgery on T2D and underlines the importance of the GI tract in the homeostatic regulation of energy balance in humans. The anti-incretin concept is currently based on a limited amount of evidence and certainly requires further validation by additional studies. The aim of the present review is to discuss and critically evaluate recent evidence on the anti-incretin theory, providing an insight into current state and future perspectives.
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Affiliation(s)
- Spyridon N Karras
- Division of Endocrinology and Metabolism and Diabetes Center, First Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, AHEPA University Hospital, Thessaloniki, Greece
| | - Theocharis Koufakis
- Division of Endocrinology and Metabolism and Diabetes Center, First Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, AHEPA University Hospital, Thessaloniki, Greece
| | - Omar G Mustafa
- Department of Diabetes, King's College Hospital, London, UK
| | - Kalliopi Kotsa
- Division of Endocrinology and Metabolism and Diabetes Center, First Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, AHEPA University Hospital, Thessaloniki, Greece
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Clyburn C, Howe CA, Arnold AC, Lang CH, Travagli RA, Browning KN. Perinatal high-fat diet alters development of GABA A receptor subunits in dorsal motor nucleus of vagus. Am J Physiol Gastrointest Liver Physiol 2019; 317:G40-G50. [PMID: 31042399 PMCID: PMC6689732 DOI: 10.1152/ajpgi.00079.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 04/22/2019] [Accepted: 04/29/2019] [Indexed: 01/31/2023]
Abstract
Perinatal high-fat diet (pHFD) exposure increases the inhibition of dorsal motor nucleus of the vagus (DMV) neurons, potentially contributing to the dysregulation of gastric functions. The aim of this study was to test the hypothesis that pHFD increases the inhibition of DMV neurons by disrupting GABAA receptor subunit development. In vivo gastric recordings were made from adult anesthetized Sprague-Dawley rats fed a control or pHFD (14 or 60% kcal from fat, respectively) from embryonic day 13 (E13) to postnatal day 42 (P42), and response to brainstem microinjection of benzodiazepines was assessed. Whole cell patch clamp recordings from DMV neurons assessed the functional expression of GABAA α subunits, whereas mRNA and protein expression were measured via qPCR and Western blotting, respectively. pHFD decreased basal antrum and corpus motility, whereas brainstem microinjection of L838,417 (positive allosteric modulator of α2/3 subunit-containing GABAA receptors) produced a larger decrease in gastric tone and motility. GABAergic miniature inhibitory postsynaptic currents in pHFD DMV neurons were responsive to L838,417 throughout development, unlike control DMV neurons, which were responsive only at early postnatal timepoints. Brainstem mRNA and protein expression of the GABAA α1,2, and 3 subunits, however, did not differ between control and pHFD rats. This study suggests that pHFD exposure arrests the development of synaptic GABAA α2/3 receptor subunits on DMV neurons and that functional synaptic expression is maintained into adulthood, although cellular localization may differ. The tonic activation of slower GABAA α2/3 subunit-containing receptors implies that such developmental changes may contribute to the observed decreased gastric motility. NEW & NOTEWORTHY Vagal neurocircuits involved in the control of gastric functions, satiation, and food intake are subject to significant developmental regulation postnatally, with immature GABAA receptors expressing slower α2/3-subunits, whereas mature GABAA receptor express faster α1-subunits. After perinatal high-fat diet exposure, this developmental regulation of dorsal motor nucleus of the vagus (DMV) neurons is disrupted, increasing their tonic GABAergic inhibition, decreasing efferent output, and potentially decreasing gastric motility.
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Affiliation(s)
- Courtney Clyburn
- Department of Neural and Behavioral Sciences, Penn State College of Medicine , Hershey, Pennsylvania
| | - Caitlin A Howe
- Department of Neural and Behavioral Sciences, Penn State College of Medicine , Hershey, Pennsylvania
| | - Amy C Arnold
- Department of Neural and Behavioral Sciences, Penn State College of Medicine , Hershey, Pennsylvania
| | - Charles H Lang
- Department of Cellular and Molecular Physiology, Penn State College of Medicine , Hershey, Pennsylvania
| | - R Alberto Travagli
- Department of Neural and Behavioral Sciences, Penn State College of Medicine , Hershey, Pennsylvania
| | - Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State College of Medicine , Hershey, Pennsylvania
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Suarez AN, Noble EE, Kanoski SE. Regulation of Memory Function by Feeding-Relevant Biological Systems: Following the Breadcrumbs to the Hippocampus. Front Mol Neurosci 2019; 12:101. [PMID: 31057368 PMCID: PMC6482164 DOI: 10.3389/fnmol.2019.00101] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/03/2019] [Indexed: 12/15/2022] Open
Abstract
The hippocampus (HPC) controls fundamental learning and memory processes, including memory for visuospatial navigation (spatial memory) and flexible memory for facts and autobiographical events (declarative memory). Emerging evidence reveals that hippocampal-dependent memory function is regulated by various peripheral biological systems that are traditionally known for their roles in appetite and body weight regulation. Here, we argue that these effects are consistent with a framework that it is evolutionarily advantageous to encode and recall critical features surrounding feeding behavior, including the spatial location of a food source, social factors, post-absorptive processing, and other episodic elements of a meal. We review evidence that gut-to-brain communication from the vagus nerve and from feeding-relevant endocrine systems, including ghrelin, insulin, leptin, and glucagon-like peptide-1 (GLP-1), promote hippocampal-dependent spatial and declarative memory via neurotrophic and neurogenic mechanisms. The collective literature reviewed herein supports a model in which various stages of feeding behavior and hippocampal-dependent memory function are closely linked.
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Affiliation(s)
| | | | - Scott E. Kanoski
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
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15
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de Lartigue G, McDougle M. Dorsal striatum dopamine oscillations: Setting the pace of food anticipatory activity. Acta Physiol (Oxf) 2019; 225:e13152. [PMID: 29920950 DOI: 10.1111/apha.13152] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Revised: 06/08/2018] [Accepted: 06/11/2018] [Indexed: 12/15/2022]
Abstract
Predicting the uncertainties of the ever-changing environment provides a competitive advantage for animals. The need to anticipate food sources has provided a strong evolutionary drive for synchronizing behavioural and internal processes with daily circadian cycles. When food is restricted to a few hours per day, rodents exhibit increased wakefulness and foraging behaviour preceding the arrival of food. Interestingly, while the master clock located in the suprachiasmatic nucleus entrains daily rhythms to the light cycle, it is not necessary for this food anticipatory activity. This suggests the existence of a food-entrained oscillator located elsewhere. Based on the role of nigrostriatal dopamine in reward processing, motor function, working memory and internal timekeeping, we propose a working model by which food-entrained dopamine oscillations in the dorsal striatum can enable animals maintained on a restricted feeding schedule to anticipate food arrival. Finally, we summarize how metabolic signals in the gut are conveyed to the nigrostriatal pathway to suggest possible insight into potential input mechanisms for food anticipatory activity.
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Affiliation(s)
- Guillaume de Lartigue
- The John B. Pierce Laboratory; New Haven Connecticut
- Department of Cellular and Molecular Physiology; Yale Medical School; New Haven Connecticut
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16
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McMenamin CA, Travagli RA, Browning KN. Perinatal high fat diet increases inhibition of dorsal motor nucleus of the vagus neurons regulating gastric functions. Neurogastroenterol Motil 2018; 30:10.1111/nmo.13150. [PMID: 28762595 PMCID: PMC5739938 DOI: 10.1111/nmo.13150] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 06/07/2017] [Indexed: 01/02/2023]
Abstract
BACKGROUND Previous studies suggest an increased inhibition of dorsal motor nucleus of the vagus (DMV) neurons following exposure to a perinatal high fat diet (PNHFD); the underlying neural mechanisms, however, remain unknown. This study assessed the effects of PNHFD on inhibitory synaptic inputs to DMV neurons and the vagally dependent control of gastric tone and motility. METHODS Whole-cell patch clamp recordings were made from DMV neurons in thin brainstem slices from Sprague-Dawley rats fed either a control diet or HFD (14 or 60% kcal from fat, respectively) from embryonic day 13 onwards; gastric tone and motility were recorded in in vivo anesthetized rats. KEY RESULTS The non-selective GABAA antagonist, BIC (10 μmol L-1 ), induced comparable inward currents in PNHFD and control DMV neurons, but a larger current in PNHFD neurons at higher concentrations (50 μmol L-1 ). Differences were not apparent in neuronal responses to the phasic GABAA antagonist, gabazine (GBZ), the extrasynaptic GABAA agonist, THIP, the GABA transport blocker, nipecotic acid, or the gliotoxin, fluoroacetate, suggesting that PNHFD altered inhibitory transmission but not GABAA receptor density or function, GABA uptake or glial modulation of synaptic strength. Similarly, the increase in gastric motility and tone following brainstem microinjection of low doses of BIC (1-10 pmoles) and GBZ (0.01-0.1 pmoles) were unchanged in PNHFD rats while higher doses of BIC (25 pmoles) induced a significantly larger increase in gastric tone compared to control. CONCLUSIONS AND INFERENCES These studies suggest that exposure to PNHFD increases the tonic inhibition of DMV neurons, possibly contributing to dysregulated vagal control of gastric functions.
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Affiliation(s)
| | | | - Kirsteen N. Browning
- Address for correspondence: Kirsteen N Browning, PhD, Department of Neural and Behavioral Science, Penn State College of Medicine, 500 University Drive, MC H109, Hershey, PA 17033, Tel: 717 531 8267,
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Abstract
This review discusses the regulation of the intestinal and hypothalamic apolipoprotein A-IV (apo A-IV) gene and protein expression. Apo A-IV is a glycoprotein secreted together with triglyceride-rich lipoproteins by the small intestine. Intestinal apo A-IV synthesis is stimulated by fat absorption, probably mediated by chylomicron formation. This stimulation of intestinal apo A-IV synthesis is attenuated by intravenous leptin infusion. Chronic ingestion of a high-fat diet blunts the intestinal apo A-IV in response to dietary lipid. Intestinal apo A-IV synthesis is also stimulated by members of the pancreatic polypeptide family, including peptide YY (PYY), neuropeptide Y (NPY), and pancreatic polypeptide (PP). Recently, apo A-IV was demonstrated to be present in the hypothalamus as well. Hypothalamic apo A-IV level was reduced by food deprivation and restored by lipid feeding. Intracerebroventricular administration of apo A-IV antiserum stimulated feeding and decreased the hypothalamic apo A-IV mRNA level, implying that feeding is intimately regulated by endogenous hypothalamic apo A-IV. Central administration of NPY significantly increased hypothalamic apo A-IV mRNA levels in a dose-dependent manner.
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Affiliation(s)
- Min Liu
- Department of Pathology and Laboratory Medicine, University of Cincinnati Medical College, Cincinnati, Ohio 45267-0529, USA
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18
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de Lartigue G. Role of the vagus nerve in the development and treatment of diet-induced obesity. J Physiol 2016; 594:5791-5815. [PMID: 26959077 DOI: 10.1113/jp271538] [Citation(s) in RCA: 154] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 02/26/2016] [Indexed: 12/21/2022] Open
Abstract
This review highlights evidence for a role of the vagus nerve in the development of obesity and how targeting the vagus nerve with neuromodulation or pharmacology can be used as a therapeutic treatment of obesity. The vagus nerve innervating the gut plays an important role in controlling metabolism. It communicates peripheral information about the volume and type of nutrients between the gut and the brain. Depending on the nutritional status, vagal afferent neurons express two different neurochemical phenotypes that can inhibit or stimulate food intake. Chronic ingestion of calorie-rich diets reduces sensitivity of vagal afferent neurons to peripheral signals and their constitutive expression of orexigenic receptors and neuropeptides. This disruption of vagal afferent signalling is sufficient to drive hyperphagia and obesity. Furthermore neuromodulation of the vagus nerve can be used in the treatment of obesity. Although the mechanisms are poorly understood, vagal nerve stimulation prevents weight gain in response to a high-fat diet. In small clinical studies, in patients with depression or epilepsy, vagal nerve stimulation has been demonstrated to promote weight loss. Vagal blockade, which inhibits the vagus nerve, results in significant weight loss. Vagal blockade is proposed to inhibit aberrant orexigenic signals arising in obesity as a putative mechanism of vagal blockade-induced weight loss. Approaches and molecular targets to develop future pharmacotherapy targeted to the vagus nerve for the treatment of obesity are proposed. In conclusion there is strong evidence that the vagus nerve is involved in the development of obesity and it is proving to be an attractive target for the treatment of obesity.
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Affiliation(s)
- Guillaume de Lartigue
- The John B. Pierce Laboratory, New Haven, CT, USA. .,Dept Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA.
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19
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Abstract
PURPOSE OF REVIEW In response to nutrient availability, the small intestine and brain closely communicate to modulate energy homeostasis and metabolism. The gut-brain axis involves complex nutrient sensing mechanisms and an integration of neuronal and hormonal signaling. This review summarizes recent evidence implicating the gut-brain axis in regulating lipoprotein metabolism, with potential implications for the dyslipidemia of insulin resistant states. RECENT FINDINGS The intestine and brain possess distinct mechanisms for sensing lipid availability, which triggers subsequent regulation of feeding, glucose homeostasis, and adipose tissue metabolism. More recently, central receptors, neuropeptides, and gut hormones that communicate with the brain have been shown to modulate hepatic and intestinal lipoprotein metabolism via parasympathetic and sympathetic signaling. Gut-derived glucagon-like peptides appear to be particularly important in modulating the intestinal secretion of chylomicron particles via a novel brain-gut axis. Dysregulation of these pathways may contribute to postprandial diabetic dyslipidemia. SUMMARY Emerging evidence implicates the central and enteric nervous systems in controlling many aspects of lipid and lipoprotein metabolism. Bidirectional communication between the gut and brain involving neuronal pathways and gut peptides is critical for regulating feeding and metabolism, and forms a neuroendocrine circuit to modulate dietary fat absorption and intestinal production of atherogenic chylomicron particles.
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Affiliation(s)
- Sarah Farr
- aMolecular Structure and Function, Research Institute, The Hospital for Sick Children bDepartment of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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20
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Troy AE, Simmonds SS, Stocker SD, Browning KN. High fat diet attenuates glucose-dependent facilitation of 5-HT3 -mediated responses in rat gastric vagal afferents. J Physiol 2015; 594:99-114. [PMID: 26456775 DOI: 10.1113/jp271558] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 10/04/2015] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS Glucose regulates the density and function of 5-HT3 receptors on gastric vagal afferent neurones. Diet-induced obesity compromises the excitability and responsiveness of vagal afferents. In this study, we assessed whether exposure to a high fat diet (HFD) compromises the glucose-dependent modulation of 5-HT responses in gastric vagal afferents prior to the development of obesity. We show that HFD does not alter the response of gastric vagal afferent nerves and neurones to 5-HT but attenuates the ability of glucose to amplify 5-HT3-induced responses. These results suggest that glucose-dependent vagal afferent signalling is compromised by relatively short periods of exposure to HFD well in advance of the development of obesity or glycaemic dysregulation. Glucose regulates the density and function of 5-HT3 receptors on gastric vagal afferent neurones. Since diet-induced obesity attenuates the responsiveness of gastric vagal afferents to several neurohormones, the aim of the present study was to determine whether high fat diet (HFD) compromises the glucose-dependent modulation of 5-HT responses in gastric vagal afferents prior to the development of obesity. Rats were fed control or HFD (14% or 60% kilocalories from fat, respectively) for up to 8 weeks. Neurophysiological recordings assessed the ability of 5-HT to increase anterior gastric vagal afferent nerve (VAN) activity in vivo before and after acute hyperglycaemia, while electrophysiological recordings from gastric-projecting nodose neurones assessed the ability of glucose to modulate the 5-HT response in vitro. Immunocytochemical studies determined alterations in the neuronal distribution of 5-HT3 receptors. 5-HT and cholecystokinin (CCK) induced dose-dependent increases in VAN activity in all rats; HFD attenuated the response to CCK, but not 5-HT. The 5-HT-induced response was amplified by acute hyperglycaemia in control, but not HFD, rats. Similarly, although 5-HT induced an inward current in both control and HFD gastric nodose neurones in vitro, the 5-HT response and receptor distribution was amplified by acute hyperglycaemia only in control rats. These data suggest that, while HFD does not affect the response of gastric-projecting vagal afferents to 5-HT, it attenuates the ability of glucose to amplify 5-HT effects. This suggests that glucose-dependent vagal afferent signalling is compromised by short periods of exposure to HFD well in advance of obesity or glycaemic dysregulation.
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Affiliation(s)
- Amanda E Troy
- Department of Neural and Behavioural Sciences, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - Sarah S Simmonds
- Department of Cellular and Integrative Physiology, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - Sean D Stocker
- Department of Neural and Behavioural Sciences, Penn State University College of Medicine, Hershey, PA, 17033, USA.,Department of Cellular and Integrative Physiology, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - Kirsteen N Browning
- Department of Neural and Behavioural Sciences, Penn State University College of Medicine, Hershey, PA, 17033, USA
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21
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Browning KN. Role of central vagal 5-HT3 receptors in gastrointestinal physiology and pathophysiology. Front Neurosci 2015; 9:413. [PMID: 26578870 PMCID: PMC4625078 DOI: 10.3389/fnins.2015.00413] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 10/15/2015] [Indexed: 12/21/2022] Open
Abstract
Vagal neurocircuits are vitally important in the co-ordination and modulation of GI reflexes and homeostatic functions. 5-hydroxytryptamine (5-HT; serotonin) is critically important in the regulation of several of these autonomic gastrointestinal (GI) functions including motility, secretion and visceral sensitivity. While several 5-HT receptors are involved in these physiological responses, the ligand-gated 5-HT3 receptor appears intimately involved in gut-brain signaling, particularly via the afferent (sensory) vagus nerve. 5-HT is released from enterochromaffin cells in response to mechanical or chemical stimulation of the GI tract which leads to activation of 5-HT3 receptors on the terminals of vagal afferents. 5-HT3 receptors are also present on the soma of vagal afferent neurons, including GI vagal afferent neurons, where they can be activated by circulating 5-HT. The central terminals of vagal afferents also exhibit 5-HT3 receptors that function to increase glutamatergic synaptic transmission to second order neurons of the nucleus tractus solitarius within the brainstem. While activation of central brainstem 5-HT3 receptors modulates visceral functions, it is still unclear whether central vagal neurons, i.e., nucleus of the tractus solitarius (NTS) and dorsal motor nucleus of the vagus (DMV) neurons themselves also display functional 5-HT3 receptors. Thus, activation of 5-HT3 receptors may modulate the excitability and activity of gastrointestinal vagal afferents at multiple sites and may be involved in several physiological and pathophysiological conditions, including distention- and chemical-evoked vagal reflexes, nausea, and vomiting, as well as visceral hypersensitivity.
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Affiliation(s)
- Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine Hershey, PA, USA
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22
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Heinze JM, Preissl H, Fritsche A, Frank S. Controversies in fat perception. Physiol Behav 2015; 152:479-93. [PMID: 26340857 DOI: 10.1016/j.physbeh.2015.08.033] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 08/25/2015] [Accepted: 08/26/2015] [Indexed: 12/22/2022]
Abstract
Nutritional fat is one of the most controversial topics in nutritional research, particularly against the background of obesity. Studies investigating fat taste perception have revealed several associations with sensory, genetic, and personal factors (e.g. BMI). However, neuronal activation patterns, which are known to be highly sensitive to different tastes as well as to BMI differences, have not yet been included in the scheme of fat taste perception. We will therefore provide a comprehensive survey of the sensory, genetic, and personal factors associated with fat taste perception and highlight the benefits of applying neuroimaging research. We will also give a critical overview of studies investigating sensory fat perception and the challenges resulting from multifaceted methodological approaches. In conclusion, we will discuss a multifactorial approach to fat perception to gain a better understanding of the underlying mechanisms that cause varying fat sensitivity which could be responsible for overeating. Such knowledge might be beneficial in new treatment strategies for obesity and overweight.
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Affiliation(s)
- Jaana M Heinze
- Institute of Medical Psychology and Behavioral Neurobiology/fMEG Center, University of Tübingen, Otfried Müller Str. 47, 72076 Tübingen, Germany; Department of Internal Medicine IV, University Hospital Tübingen, Otfried Müller Str. 10, 72076 Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Otfried Müller Str. 47, 72076 Tübingen, Germany; German Center for Diabetes Research, Otfried Müller Str. 47, 72076 Tübingen, Germany
| | - Hubert Preissl
- Department of Internal Medicine IV, University Hospital Tübingen, Otfried Müller Str. 10, 72076 Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Otfried Müller Str. 47, 72076 Tübingen, Germany; German Center for Diabetes Research, Otfried Müller Str. 47, 72076 Tübingen, Germany.
| | - Andreas Fritsche
- Department of Internal Medicine IV, University Hospital Tübingen, Otfried Müller Str. 10, 72076 Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Otfried Müller Str. 47, 72076 Tübingen, Germany; German Center for Diabetes Research, Otfried Müller Str. 47, 72076 Tübingen, Germany
| | - Sabine Frank
- Institute of Medical Psychology and Behavioral Neurobiology/fMEG Center, University of Tübingen, Otfried Müller Str. 47, 72076 Tübingen, Germany
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Browning KN, Travagli RA. Central nervous system control of gastrointestinal motility and secretion and modulation of gastrointestinal functions. Compr Physiol 2015; 4:1339-68. [PMID: 25428846 DOI: 10.1002/cphy.c130055] [Citation(s) in RCA: 322] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Although the gastrointestinal (GI) tract possesses intrinsic neural plexuses that allow a significant degree of autonomy over GI functions, the central nervous system (CNS) provides extrinsic neural inputs that regulate, modulate, and control these functions. While the intestines are capable of functioning in the absence of extrinsic inputs, the stomach and esophagus are much more dependent upon extrinsic neural inputs, particularly from parasympathetic and sympathetic pathways. The sympathetic nervous system exerts a predominantly inhibitory effect upon GI muscle and provides a tonic inhibitory influence over mucosal secretion while, at the same time, regulates GI blood flow via neurally mediated vasoconstriction. The parasympathetic nervous system, in contrast, exerts both excitatory and inhibitory control over gastric and intestinal tone and motility. Although GI functions are controlled by the autonomic nervous system and occur, by and large, independently of conscious perception, it is clear that the higher CNS centers influence homeostatic control as well as cognitive and behavioral functions. This review will describe the basic neural circuitry of extrinsic inputs to the GI tract as well as the major CNS nuclei that innervate and modulate the activity of these pathways. The role of CNS-centered reflexes in the regulation of GI functions will be discussed as will modulation of these reflexes under both physiological and pathophysiological conditions. Finally, future directions within the field will be discussed in terms of important questions that remain to be resolved and advances in technology that may help provide these answers.
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Affiliation(s)
- Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania
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24
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Bhagat R, Fortna SR, Browning KN. Exposure to a high fat diet during the perinatal period alters vagal motoneurone excitability, even in the absence of obesity. J Physiol 2014; 593:285-303. [PMID: 25556801 DOI: 10.1113/jphysiol.2014.282806] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 10/24/2014] [Indexed: 01/02/2023] Open
Abstract
KEY POINTS Obesity is recognized as being multifactorial in origin, involving both genetic and environmental factors. The perinatal period is known to be critically important in the development of neural circuits responsible for energy homeostasis and the integration of autonomic reflexes. Diet-induced obesity alters the biophysical, pharmacological and morphological properties of vagal neurocircuits regulating upper gastrointestinal tract functions, including satiety. Less information is available, however, regarding the effects of a high fat diet (HFD) itself on the properties of vagal neurocircuits. The present study was designed to test the hypothesis that exposure to a HFD during the perinatal period alters the electrophysiological, pharmacological and morphological properties of vagal efferent motoneurones innervating the stomach. Our data indicate that perinatal HFD decreases the excitability of gastric-projecting dorsal motor nucleus neurones and dysregulates neurotransmitter release from synaptic inputs and that these alterations occur prior to the development of obesity. These findings represent the first direct evidence that exposure to a HFD modulates the processing of central vagal neurocircuits even in the absence of obesity. The perinatal period is critically important to the development of autonomic neural circuits responsible for energy homeostasis. Vagal neurocircuits are vital to the regulation of upper gastrointestinal functions, including satiety. Diet-induced obesity modulates the excitability and responsiveness of both peripheral vagal afferents and central vagal efferents but less information is available regarding the effects of diet per se on vagal neurocircuit functions. The aims of this study were to investigate whether perinatal exposure to a high fat diet (HFD) dysregulated dorsal motor nucleus of the vagus (DMV) neurones, prior to the development of obesity. Whole cell patch clamp recordings were made from gastric-projecting DMV neurones in thin brainstem slices from rats that were exposed to either a control diet or HFD from pregnancy day 13. Our data demonstrate that following perinatal HFD: (i) DMV neurones had decreased excitability and input resistance with a reduced ability to fire action potentials; (ii) the proportion of DMV neurones excited by cholecystokinin (CCK) was unaltered but the proportion of neurones in which CCK increased excitatory glutamatergic synaptic inputs was reduced; (iii) the tonic activation of presynaptic group II metabotropic glutamate receptors on inhibitory nerve terminals was attenuated, allowing modulation of GABAergic synaptic transmission; and (iv) the size and dendritic arborization of gastric-projecting DMV neurones was increased. These results suggest that perinatal HFD exposure compromises the excitability and responsiveness of gastric-projecting DMV neurones, even in the absence of obesity, suggesting that attenuation of vago-vagal reflex signalling may precede the development of obesity.
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Affiliation(s)
- Ruchi Bhagat
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, USA
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Abstract
Overconsumption of dietary fat contributes to the development of obesity and metabolic syndrome. Recent evidence suggests that high dietary fat may promote these metabolic states not only by providing calories but also by inducing impaired control of energy balance. In normal metabolic states, fat interacts with various organs or receptors to generate signals for the regulation of energy balance. Many of these interactions are impaired by high-fat diets or in obesity, contributing to the development or maintenance of obesity. These impairments may arise largely from fundamental alterations in the hypothalamus where all peripheral signals are integrated to regulate energy balance. This review focuses on various mechanisms by which fat is sensed at different stages of ingestion, circulation, storage, and utilization to regulate food intake, and how these individual mechanisms are altered by high-fat diets or in obesity.
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Affiliation(s)
- Jang H Youn
- Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, Los Angeles, CA, USA,
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Dunn TN, Adams SH. Relations between metabolic homeostasis, diet, and peripheral afferent neuron biology. Adv Nutr 2014; 5:386-93. [PMID: 25022988 PMCID: PMC4085187 DOI: 10.3945/an.113.005439] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
It is well established that food intake behavior and energy balance are regulated by crosstalk between peripheral organ systems and the central nervous system (CNS), for instance, through the actions of peripherally derived leptin on hindbrain and hypothalamic loci. Diet- or obesity-associated disturbances in metabolic and hormonal signals to the CNS can perturb metabolic homeostasis bodywide. Although interrelations between metabolic status and diet with CNS biology are well characterized, afferent networks (those sending information to the CNS from the periphery) have received far less attention. It is increasingly appreciated that afferent neurons in adipose tissue, the intestines, liver, and other tissues are important controllers of energy balance and feeding behavior. Disruption in their signaling may have consequences for cardiovascular, pancreatic, adipose, and immune function. This review discusses the diverse ways that afferent neurons participate in metabolic homeostasis and highlights how changes in their function associate with dysmetabolic states, such as obesity and insulin resistance.
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Affiliation(s)
- Tamara N. Dunn
- Graduate Group in Nutritional Biology and Department of Nutrition, University of California, Davis, CA; and
| | - Sean H. Adams
- Graduate Group in Nutritional Biology and Department of Nutrition, University of California, Davis, CA; and,Obesity and Metabolism Research Unit, USDA–Agricultural Research Service Western Human Nutrition Research Center, Davis, CA,To whom correspondence should be addressed. E-mail:
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Neunlist M, Schemann M. Nutrient-induced changes in the phenotype and function of the enteric nervous system. J Physiol 2014; 592:2959-65. [PMID: 24907307 DOI: 10.1113/jphysiol.2014.272948] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The enteric nervous system (ENS) integrates numerous sensory signals in order to control and maintain normal gut functions. Nutrients are one of the prominent factors which determine the chemical milieu in the lumen and, after absorption, also within the gut wall. This review summarizes current knowledge on the impact of key nutrients on ENS functions and phenotype, covering their acute and long-term effects. Enteric neurones contain the molecular machinery to respond specifically to nutrients. These transporters and receptors are not expressed exclusively in the ENS but are also present in other cells such as enteroendocrine cells (EECs) and extrinsic sensory nerves, signalling satiety or hunger. Glucose, amino acids and fatty acids all activate enteric neurones, as suggested by enhanced c-Fos expression or spike discharge. These excitatory effects are the result of a direct neuronal activation but also involve the activation of EECs which, upon activation by luminal nutrients, release mediators such as ghrelin, cholecystokinin or serotonin. The presence or absence of nutrients in the intestinal lumen induces long-term changes in neurotransmitter expression, excitability, neuronal survival and ultimately impact upon gut motility, secretion or intestinal permeability. Together with EECs and vagal nerves, the ENS must be recognized as an important player initiating concerted responses to nutrients. It remains to be studied how, for instance, nutrient-induced changes in the ENS may influence additional gut functions such as intestinal barrier repair, intestinal epithelial stem cell proliferation/differentiation and also the signalling of extrinsic nerves to brain regions which control food intake.
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Affiliation(s)
- Michel Neunlist
- INSERM, U913, Nantes, F-44093, France Université Nantes, Nantes, F-44093, France CHU Nantes, HôtelDieu, Institut des Maladies de l'Appareil Digestif, Nantes, F-44093, France Centre de Recherche en Nutrition Humaine, Nantes, F-44093, France
| | - Michael Schemann
- Lehrstuhl für Humanbiologie, Technische Universität München, Liesel-Beckmann-Straße 4, 85350, Freising-Weihenstephan, Germany
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Romano A, Karimian Azari E, Tempesta B, Mansouri A, Micioni Di Bonaventura MV, Ramachandran D, Lutz TA, Bedse G, Langhans W, Gaetani S. High dietary fat intake influences the activation of specific hindbrain and hypothalamic nuclei by the satiety factor oleoylethanolamide. Physiol Behav 2014; 136:55-62. [PMID: 24802360 DOI: 10.1016/j.physbeh.2014.04.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 04/23/2014] [Accepted: 04/27/2014] [Indexed: 12/16/2022]
Abstract
Chronic exposure to a diet rich in fats changes the gastrointestinal milieu and alters responses to several signals involved in the control of food intake. Oleoylethanolamide (OEA) is a gut-derived satiety signal released from enterocytes upon the ingestion of dietary fats. The anorexigenic effect of OEA, which requires intestinal PPAR-alpha receptors and is supposedly mediated by vagal afferents, is associated with the induction of c-fos in several brain areas involved in the control of food intake, such as the nucleus of the solitary tract (NST) and the hypothalamic paraventricular (PVN) and supraoptic nuclei (SON). In the present study we investigated whether the exposure to a high fat diet (HFD) alters the hindbrain and hypothalamic responses to OEA. To this purpose we evaluated the effects of OEA at a dose that reliably inhibits eating (10mg/kg i.p.) on the induction of c-fos in the NST, area postrema (AP), PVN and SON in rats maintained either on standard chow or a HFD. We performed a detailed analysis of the different NST subnuclei activated by i.p. OEA and found that peripheral OEA strongly activates c-fos expression in the AP, NST and in the hypothalamus of both chow and HFD fed rats. The extent of c-fos expression was, however, markedly different between the two groups of rats, with a weaker activation of selected NST subnuclei and stronger activation of the PVN in HFD-fed than in chow-fed rats. HFD-fed rats were also more sensitive to the immediate hypophagic action of OEA than chow-fed rats. These effects may be due to a decreased sensitivity of vagal afferent fibers that might mediate OEA's actions on the brain and/or an altered sensitivity of brain structures to OEA.
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Affiliation(s)
- A Romano
- Dept. of Physiology and Pharmacology "V. Erspamer", Sapienza Univ. of Rome, 00185 Rome, Italy.
| | - E Karimian Azari
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - B Tempesta
- Dept. of Physiology and Pharmacology "V. Erspamer", Sapienza Univ. of Rome, 00185 Rome, Italy
| | - A Mansouri
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | | | - D Ramachandran
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - T A Lutz
- Institute of Veterinary Physiology, Vetsuisse Faculty, and Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - G Bedse
- Dept. of Physiology and Pharmacology "V. Erspamer", Sapienza Univ. of Rome, 00185 Rome, Italy
| | - W Langhans
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - S Gaetani
- Dept. of Physiology and Pharmacology "V. Erspamer", Sapienza Univ. of Rome, 00185 Rome, Italy.
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How JMY, Wardak SA, Ameer SI, Davey RA, Sartor DM. Blunted sympathoinhibitory responses in obesity-related hypertension are due to aberrant central but not peripheral signalling mechanisms. J Physiol 2014; 592:1705-20. [PMID: 24492842 DOI: 10.1113/jphysiol.2013.269670] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The gut hormone cholecystokinin (CCK) acts at subdiaphragmatic vagal afferents to induce renal and splanchnic sympathoinhibition and vasodilatation, via reflex inhibition of a subclass of cardiovascular-controlling neurons in the rostroventrolateral medulla (RVLM). These sympathoinhibitory and vasodilator responses are blunted in obese, hypertensive rats and our aim in the present study was to determine whether this is attributable to (i) altered sensitivity of presympathetic vasomotor RVLM neurons, and (ii) aberrant peripheral or central signalling mechanisms. Using a diet-induced obesity model, male Sprague-Dawley rats exhibited either an obesity-prone (OP) or obesity-resistant (OR) phenotype when placed on a medium high fat diet for 13-15 weeks; control animals were placed on a low fat diet. OP animals had elevated resting arterial pressure compared to OR/control animals (P < 0.05). Barosensitivity of RVLM neurons was significantly attenuated in OP animals (P < 0.05), suggesting altered baroreflex gain. CCK induced inhibitory responses in RVLM neurons of OR/control animals but not OP animals. Subdiaphragmatic vagal nerve responsiveness to CCK and CCK1 receptor mRNA expression in nodose ganglia did not differ between the groups, but CCK induced significantly less Fos-like immunoreactivity in both the nucleus of the solitary tract and the caudal ventrolateral medulla of OP animals compared to controls (P < 0.05). These results suggest that blunted sympathoinhibitory and vasodilator responses in obesity-related hypertension are due to alterations in RVLM neuronal responses, resulting from aberrant central but not peripheral signalling mechanisms. In obesity, blunted sympathoinhibitory mechanisms may lead to increased regional vascular resistance and contribute to the development of hypertension.
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Browning KN, Fortna SR, Hajnal A. Roux-en-Y gastric bypass reverses the effects of diet-induced obesity to inhibit the responsiveness of central vagal motoneurones. J Physiol 2013; 591:2357-72. [PMID: 23459752 DOI: 10.1113/jphysiol.2012.249268] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Diet-induced obesity (DIO) has been shown to alter the biophysical properties and pharmacological responsiveness of vagal afferent neurones and fibres, although the effects of DIO on central vagal neurones or vagal efferent functions have never been investigated. The aims of this study were to investigate whether high-fat diet-induced DIO also affects the properties of vagal efferent motoneurones, and to investigate whether these effects were reversed following weight loss induced by Roux-en-Y gastric bypass (RYGB) surgery. Whole-cell patch-clamp recordings were made from rat dorsal motor nucleus of the vagus (DMV) neurones in thin brainstem slices. The DMV neurones from rats exposed to high-fat diet for 12-14 weeks were less excitable, with a decreased membrane input resistance and decreased ability to fire action potentials in response to direct current pulse injection. The DMV neurones were also less responsive to superfusion with the satiety neuropeptides cholecystokinin and glucagon-like peptide 1. Roux-en-Y gastric bypass reversed all of these DIO-induced effects. Diet-induced obesity also affected the morphological properties of DMV neurones, increasing their size and dendritic arborization; RYGB did not reverse these morphological alterations. Remarkably, independent of diet, RYGB also reversed age-related changes of membrane properties and occurrence of charybdotoxin-sensitive (BK) calcium-dependent potassium current. These results demonstrate that DIO also affects the properties of central autonomic neurones by decreasing the membrane excitability and pharmacological responsiveness of central vagal motoneurones and that these changes were reversed following RYGB. In contrast, DIO-induced changes in morphological properties of DMV neurones were not reversed following gastric bypass surgery, suggesting that they may be due to diet, rather than obesity. These findings represent the first direct evidence for the plausible effect of RYGB to improve vagal neuronal health in the brain by reversing some effects of chronic high-fat diet as well as ageing. Vagovagal neurocircuits appear to remain open to modulation and adaptation throughout life, and understanding of these mechanisms may help in development of novel interventions to alleviate environmental (e.g. dietary) ailments and also alter neuronal ageing.
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Affiliation(s)
- Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, USA.
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31
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Park JH, Kwon OD, Ahn SH, Lee S, Choi BK, Jung KY. Fatty diets retarded the propulsive function of and attenuated motility in the gastrointestinal tract of rats. Nutr Res 2013; 33:228-34. [DOI: 10.1016/j.nutres.2012.12.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 12/17/2012] [Accepted: 12/28/2012] [Indexed: 12/01/2022]
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Amin A, Murphy KG. Nutritional sensing and its utility in treating obesity. Expert Rev Endocrinol Metab 2012; 7:209-221. [PMID: 30764012 DOI: 10.1586/eem.12.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Obesity remains a major worldwide health problem, with current medical treatments being poorly effective. Nutrient sensing allows organs such as the GI tract and the brain to recognize and respond to fuel substrates such as carbohydrates, protein and fats. Specialized neural and hormonal pathways exist to facilitate and regulate these chemosensory mechanisms. Manipulation of factors involved in either central or peripheral chemosensory pathways may provide possible targets for the manipulation of appetite. However, further research is required to assess the utility of this approach to developing novel anti-obesity agents.
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Affiliation(s)
- Anjali Amin
- a Section of Investigative Medicine, Faculty of Medicine, Imperial College London, 6th Floor, Commonwealth Building, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Kevin G Murphy
- b Section of Investigative Medicine, Faculty of Medicine, Imperial College London, 6th Floor, Commonwealth Building, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
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Pepino MY, Love-Gregory L, Klein S, Abumrad NA. The fatty acid translocase gene CD36 and lingual lipase influence oral sensitivity to fat in obese subjects. J Lipid Res 2011; 53:561-566. [PMID: 22210925 DOI: 10.1194/jlr.m021873] [Citation(s) in RCA: 201] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The precise orosensory inputs engaged for dietary lipids detection in humans are unknown. We evaluated whether a common single nucleotide polymorphism (rs1761667) in the CD36 gene that reduces CD36 expression and the addition of orlistat, a lipase inhibitor, to reduce FA release from triacylglycerols (TGs), the main component of dietary fats, would attenuate fat orosensory sensitivity in humans. Twenty-one obese subjects with different rs1761667 genotypes (6 AA, 7 AG, and 8 GG) were studied on two occasions in which oleic acid and triolein orosensory detection thresholds were measured using emulsions prepared with and without orlistat. Subjects homozygous for the G-allele had 8-fold lower oral detection thresholds for oleic acid and triolein than subjects homozygous for the A allele, which associates with lower CD36 expression (P = 0.03). Thresholds for heterozygous subjects were intermediate. The addition of orlistat increased detection thresholds for triolein (log threshold = -0.3 ± 0.2 vs. 0.3 ± 0.1; P < 0.001) but not oleic acid (log threshold = -1.0 ± 0.2 vs. -0.8 ± 0.2; P > 0.2). In conclusion, this is the first experimental evidence for a role of CD36 in fat gustatory perception in humans. The data also support involvement of lingual lipase and are consistent with the concept that FA and not TG is the sensed stimulus.
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Affiliation(s)
- Marta Yanina Pepino
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110.
| | - Latisha Love-Gregory
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110
| | - Samuel Klein
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110
| | - Nada A Abumrad
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110
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Little TJ, Feinle-Bisset C. Effects of dietary fat on appetite and energy intake in health and obesity — Oral and gastrointestinal sensory contributions. Physiol Behav 2011; 104:613-20. [DOI: 10.1016/j.physbeh.2011.04.038] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 04/15/2011] [Accepted: 04/26/2011] [Indexed: 02/08/2023]
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Schier LA, Davidson TL, Powley TL. Ongoing ingestive behavior is rapidly suppressed by a preabsorptive, intestinal "bitter taste" cue. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1557-68. [PMID: 21865540 DOI: 10.1152/ajpregu.00344.2011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The discovery that cells in the gastrointestinal (GI) tract express the same molecular receptors and intracellular signaling components known to be involved in taste has generated great interest in potential functions of such post-oral "taste" receptors in the control of food intake. To determine whether taste cues in the GI tract are detected and can directly influence behavior, the present study used a microbehavioral analysis of intake, in which rats drank from lickometers that were programmed to simultaneously deliver a brief yoked infusion of a taste stimulus to the intestines. Specifically, in daily 30-min sessions, thirsty rats with indwelling intraduodenal catheters were trained to drink hypotonic (0.12 M) sodium chloride (NaCl) and simultaneously self-infuse a 0.12 M NaCl solution. Once trained, in a subsequent series of intestinal taste probe trials, rats reduced licking during a 6-min infusion period, when a bitter stimulus denatonium benzoate (DB; 10 mM) was added to the NaCl vehicle for infusion, apparently conditioning a mild taste aversion. Presentation of the DB in isomolar lithium chloride (LiCl) for intestinal infusions accelerated the development of the response across trials and strengthened the temporal resolution of the early licking suppression in response to the arrival of the DB in the intestine. In an experiment to evaluate whether CCK is involved as a paracrine signal in transducing the intestinal taste of DB, the CCK-1R antagonist devazepide partially blocked the response to intestinal DB. In contrast to their ability to detect and avoid the bitter taste in the intestine, rats did not modify their licking to saccharin intraduodenal probe infusions. The intestinal taste aversion paradigm developed here provides a sensitive and effective protocol for evaluating which tastants-and concentrations of tastants-in the lumen of the gut can control ingestion.
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Affiliation(s)
- Lindsey A Schier
- Dept. of Psychological Sciences, 703 Third St., Purdue Univ., West Lafayette, IN 47907, USA.
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Daly DM, Park SJ, Valinsky WC, Beyak MJ. Impaired intestinal afferent nerve satiety signalling and vagal afferent excitability in diet induced obesity in the mouse. J Physiol 2011; 589:2857-70. [PMID: 21486762 DOI: 10.1113/jphysiol.2010.204594] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Gastrointestinal vagal afferents transmit satiety signals to the brain via both chemical and mechanical mechanisms. There is indirect evidence that these signals may be attenuated in obesity. We hypothesized that responses to satiety mediators and distension of the gut would be attenuated after induction of diet induced obesity. Obesity was induced by feeding a high fat diet (60% kcal from fat). Low fat fed mice (10% kcal from fat) served as a control. High fat fed mice were obese, with increased visceral fat, but were not hyperglycaemic. Recordings from jejunal afferents demonstrated attenuated responses to the satiety mediators cholecystokinin (CCK, 100 nm) and 5-hydroxytryptamine (5-HT, 10 μm), as was the response to low intensity jejunal distension, while responses to higher distension pressures were preserved. We performed whole cell patch clamp recordings on nodose ganglion neurons, both unlabelled, and those labelled by fast blue injection into the wall of the jejunum. The cell membrane of both labelled and unlabelled nodose ganglion neurons was less excitable in HFF mice, with an elevated rheobase and decreased number of action potentials at twice rheobase. Input resistance of HFF neurons was also significantly decreased. Calcium imaging experiments revealed reduced proportion of nodose ganglion neurons responding to CCK and 5-HT in obese mice. These results demonstrate a marked reduction in afferent sensitivity to satiety related stimuli after a chronic high fat diet. A major mechanism underlying this change is reduced excitability of the neuronal cell membrane. This may explain the development of hyperphagia when a high fat diet is consumed. Improving sensitivity of gastrointestinal afferent nerves may prove useful to limit food intake in obesity.
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Affiliation(s)
- Donna M Daly
- Departments of Medicine and Physiology, Gastrointestinal Diseases Research Unit (GIDRU) Wing, Kingston General Hospital, 76 Stuart Street, Kingston, Ontario, Canada K7L2V7
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How JMY, Fam BC, Verberne AJM, Sartor DM. High-fat diet is associated with blunted splanchnic sympathoinhibitory responses to gastric leptin and cholecystokinin: implications for circulatory control. Am J Physiol Heart Circ Physiol 2011; 300:H961-7. [DOI: 10.1152/ajpheart.01156.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Gastric leptin and cholecystokinin (CCK) act on vagal afferents to induce cardiovascular effects and reflex inhibition of splanchnic sympathetic nerve discharge (SSND) and may act cooperatively in these responses. We sought to determine whether these effects are altered in animals that developed obesity in response to a medium high-fat diet (MHFD). Male Sprague-Dawley rats were placed on a low-fat diet (LFD; n = 8) or a MHFD ( n = 24) for 13 wk, after which the animals were anesthetized and artificially ventilated. Arterial pressure was monitored and blood was collected for the determination of plasma leptin and CCK. SSND responses to leptin (15 μg/kg) and CCK (2 μg/kg) administered close to the coeliac artery were evaluated. Collectively, MHFD animals had significantly higher plasma leptin but lower plasma CCK levels than LFD rats ( P < 0.05), and this corresponded to attenuated or reversed SSND responses to CCK (LFD, −21 ± 2%; and MHFD, −12 ± 2%; P < 0.05) and leptin (LFD, −6 ± 2%; and MHFD, 4 ± 1%; P < 0.001). Alternatively, animals on the MHFD were stratified into obesity-prone (OP; n = 8) or obesity-resistant (OR; n = 8) groups according to their weight gain falling within the upper or lower tertile, respectively. OP rats had significantly higher resting arterial pressure, adiposity, and plasma leptin but lower plasma CCK compared with LFD rats ( P < 0.05). The SSND responses to CCK or leptin were not significantly different between OP and OR animals. These results demonstrate that a high-fat diet is associated with blunted splanchnic sympathoinhibitory responses to gastric leptin and CCK and may impact on sympathetic vasomotor mechanisms involved in circulatory control.
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Affiliation(s)
- Jackie M. Y. How
- Department of Medicine, University of Melbourne, Victoria, Australia
| | - Barbara C. Fam
- Department of Medicine, University of Melbourne, Victoria, Australia
| | | | - Daniela M. Sartor
- Department of Medicine, University of Melbourne, Victoria, Australia
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Brennan IM, Seimon RV, Luscombe-Marsh ND, Otto B, Horowitz M, Feinle-Bisset C. Effects of acute dietary restriction on gut motor, hormone and energy intake responses to duodenal fat in obese men. Int J Obes (Lond) 2011; 35:448-56. [PMID: 20680017 DOI: 10.1038/ijo.2010.153] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Previous patterns of energy intake influence gastrointestinal function and appetite, probably reflecting changes in small-intestinal nutrient-mediated feedback. Obese individuals consume more fat and may be less sensitive to its gastrointestinal and appetite-suppressant effects than lean individuals. OBJECTIVE To evaluate the hypothesis that, in obese individuals, the effects of duodenal fat on gastrointestinal motor and hormone function, and appetite would be enhanced by a short period on a very-low-calorie diet (VLCD). METHODS Eight obese men (body mass index 34±0.6 kg m(-2)) were studied on two occasions, before (V1), and immediately after (V2), a 4-day VLCD. On both occasions, antropyloroduodenal motility, plasma cholecystokinin (CCK), peptide-YY (PYY) and ghrelin concentrations, and appetite perceptions were measured during a 120-min intraduodenal fat infusion (2.86 kcal min(-1)). Immediately afterwards, energy intake was quantified. RESULTS During V2, basal pyloric pressure and the number and amplitude of isolated pyloric pressure waves (PWs) were greater, whereas the number of antral and duodenal PWs was less, compared with V1 (all P<0.05). Moreover, during V2, baseline ghrelin concentration was higher; the stimulation of PYY and suppression of ghrelin by lipid were greater, with no difference in CCK concentration; and hunger and energy intake (kJ; V1: 4378±691, V2: 3634±700) were less (all P<0.05), compared with V1. CONCLUSIONS In obese males, the effects of small-intestinal lipid on gastrointestinal motility and some hormone responses and appetite are enhanced after a 4-day VLCD.
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Affiliation(s)
- I M Brennan
- University of Adelaide Discipline of Medicine, Royal Adelaide Hospital, Adelaide, South Australia, Australia
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Abstract
The gut plays a unique role in the metabolic defence against energy excess and glucose imbalance. Nutrients, such as lipids, enter the small intestine and activate sensing mechanisms to maintain energy and glucose homeostasis. It is clear that a lipid-induced gut-brain axis exists and that cholecystokinin and a neuronal network are involved, yet the underlying mechanisms in gut lipid sensing that regulate homeostasis remain largely unknown. In parallel, studies underscore the importance of enzymes involved in lipid metabolism within the brain, such as adenosine monophosphate -activated protein kinase, to maintain homeostasis. In this review, we will first examine what is known regarding the mechanisms involved in this lipid-induced gut-brain neuronal axis that regulate food intake and hepatic glucose production. We will also discuss how enzymes that govern brain lipid metabolism could potentially reveal how lipids trigger the gut, and that both the gut and brain may share common biochemical pathways to sense lipids.
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Affiliation(s)
- Danna M Breen
- Toronto General Research Institute, University Health Network, Toronto, Ontario M5G 1L7, Canada
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40
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Little TJ, Feinle-Bisset C. Oral and gastrointestinal sensing of dietary fat and appetite regulation in humans: modification by diet and obesity. Front Neurosci 2010; 4:178. [PMID: 21088697 PMCID: PMC2981385 DOI: 10.3389/fnins.2010.00178] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 09/23/2010] [Indexed: 01/25/2023] Open
Abstract
Dietary fat interacts with receptors in both the oral cavity and the gastrointestinal (GI) tract to regulate fat and energy intake. This review discusses recent developments in our understanding of the mechanisms underlying the effects of fat, through its digestive products, fatty acids (FAs), on GI function and energy intake, the role of oral and intestinal FA receptors, and the implications that changes in oral and small intestinal sensitivity in response to ingested fat may have for the development of obesity.
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Affiliation(s)
- Tanya J. Little
- Discipline of Medicine, Royal Adelaide Hospital, University of AdelaideAdelaide, SA, Australia
- NHMRC Centre of Clinical Research Excellence in Nutritional Physiology, Interactions and Outcomes, University of AdelaideAdelaide, SA, Australia
| | - Christine Feinle-Bisset
- Discipline of Medicine, Royal Adelaide Hospital, University of AdelaideAdelaide, SA, Australia
- NHMRC Centre of Clinical Research Excellence in Nutritional Physiology, Interactions and Outcomes, University of AdelaideAdelaide, SA, Australia
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Covasa M. Deficits in gastrointestinal responses controlling food intake and body weight. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1423-39. [PMID: 20861277 DOI: 10.1152/ajpregu.00126.2010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The gastrointestinal tract serves as a portal sensing incoming nutrients and relays mechanical and chemosensory signals of a meal to higher brain centers. Prolonged consumption of dietary fat causes adaptive changes within the alimentary, metabolic, and humoral systems that promote a more efficient process for energy metabolism from this rich source, leading to storage of energy in the form of adipose tissue. Furthermore, prolonged ingestion of dietary fats exerts profound effects on responses to signals involved in termination of a meal. This article reviews the effects of ingested fat on gastrointestinal motility, hormone release, and neuronal substrates. It focuses on changes in sensitivity to satiation signals resulting from chronic ingestion of high-fat diet, which may lead to disordered appetite and dysregulation of body weight.
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Affiliation(s)
- Mihai Covasa
- L'Institute National de la Recherche Agronomique, Centre de Recherche, Microbiologie de l'Alimentation au service de la Santé Humaine (MICALIS), Neurobiology of Ingestive Behavior, Jouy-en-Josas, France.
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42
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43
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Swartz TD, Duca FA, Covasa M. Differential feeding behavior and neuronal responses to CCK in obesity-prone and -resistant rats. Brain Res 2009; 1308:79-86. [PMID: 19857467 DOI: 10.1016/j.brainres.2009.10.045] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 10/15/2009] [Accepted: 10/18/2009] [Indexed: 02/02/2023]
Abstract
Deficits in satiation signals are strongly suspected of accompanying obesity and contributing to its pathogenesis in both humans and rats. One such satiation signal is cholecystokinin (CCK), whose effects on food intake are diminished in animals adapted to a high fat diet. In this study, we tested the hypothesis that diet-induced obese prone (OP) rats exhibit altered feeding and vagal responses to systemic (IP) administration of CCK-8 compared to diet-induced obese resistant (OR) rats. We found that CCK (4.0 microg/kg) suppressed food intake significantly more in OP than OR rats. To determine whether enhanced suppression of feeding is accompanied by altered vagal sensory responsiveness, we examined dorsal hindbrain expression of Fos-like immunoreactivity (Fos-Li) following IP CCK injection in OP and OR rats. After 4.0 microg/kg CCK, there were significantly more Fos-positive nuclei in the NTS of OP compared to OR rats. Treatment with 8.0 microg/kg CCK resulted in no significant difference in food intake or in Fos-Li between OP and OR rats. Also, we found that OP rats were hyperphagic on a regular chow diet and gained more weight compared to OR rats. Finally OP rats had decreased relative fat pad mass compared to OR rats. Collectively, these results show that OP rats exhibit a different behavioral and vagal neuronal responses to CCK than OR rats.
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Affiliation(s)
- T D Swartz
- Interdepartmental Graduate Degree Program in Physiology, Huck Institute of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
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44
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Cheung GWC, Kokorovic A, Lam TKT. Upper intestinal lipids regulate energy and glucose homeostasis. Cell Mol Life Sci 2009; 66:3023-7. [PMID: 19513587 PMCID: PMC11115480 DOI: 10.1007/s00018-009-0062-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 05/25/2009] [Accepted: 05/27/2009] [Indexed: 10/20/2022]
Abstract
Upon the entry of nutrients into the small intestine, nutrient sensing mechanisms are activated to allow the body to adapt appropriately to the incoming nutrients. To date, mounting evidence points to the existence of an upper intestinal lipid-induced gut-brain neuronal axis to regulate energy homeostasis. Moreover, a recent discovery has also revealed an upper intestinal lipid-induced gut-brain-liver neuronal axis involved in the regulation of glucose homeostasis. In this mini-review, we will focus on the mechanisms underlying the activation of these respective neuronal axes by upper intestinal lipids.
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Affiliation(s)
- Grace W. C. Cheung
- Department of Physiology, University of Toronto, Toronto, M5S 1A8 Canada
- Toronto General Research Institute, University Health Network, Toronto, M5G 1L7 Canada
| | - Andrea Kokorovic
- Department of Physiology, University of Toronto, Toronto, M5S 1A8 Canada
- Toronto General Research Institute, University Health Network, Toronto, M5G 1L7 Canada
| | - Tony K. T. Lam
- Department of Physiology, University of Toronto, Toronto, M5S 1A8 Canada
- Department of Medicine, University of Toronto, Toronto, M5S 1A8 Canada
- Toronto General Research Institute, University Health Network, Toronto, M5G 1L7 Canada
- MaRS Centre, Toronto Medical Discovery Tower, Room 10-706, 101 College Street, Toronto, ON M5G 1L7 Canada
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45
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Beyak MJ. Visceral afferents - determinants and modulation of excitability. Auton Neurosci 2009; 153:69-78. [PMID: 19674942 DOI: 10.1016/j.autneu.2009.07.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Revised: 07/13/2009] [Accepted: 07/20/2009] [Indexed: 02/06/2023]
Abstract
An essential property of visceral sensory afferents is to be able to alter their firing properties in response to changes in the microenvironment at the level of the sensory ending. Significant progress has been made in recent years in understanding the ionic mechanisms of the regulation of afferent neuronal excitability, and in identifying the mechanisms by which this can be altered. This article will review some of the recent developments in the state of knowledge regarding mechanisms of increased excitability after inflammation, and pharmacological modulation of excitability, concentrating on afferent nerves innervating the GI tract and urinary bladder.
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Affiliation(s)
- Michael J Beyak
- Department of Medicine, Queen's University, GIDRU Wing, Kingston General Hospital, 76 Stuart St, Kingston, ON, Canada K7L 2V7.
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46
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Donovan MJ, Paulino G, Raybould HE. Activation of hindbrain neurons in response to gastrointestinal lipid is attenuated by high fat, high energy diets in mice prone to diet-induced obesity. Brain Res 2008; 1248:136-40. [PMID: 19007755 DOI: 10.1016/j.brainres.2008.10.042] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Revised: 10/17/2008] [Accepted: 10/20/2008] [Indexed: 11/26/2022]
Abstract
Food intake is controlled by peripheral signals from the gastrointestinal tract and adipocytes, which are integrated within the central nervous system. There is evidence that signals from the GI tract are modulated by long term changes in diet, possibly leading to hyperphagia and increased body weight. We tested the hypothesis that diet-induced obese-prone (DIO-P) and obese-resistant (DIO-R) mice strains differ in the long term adaptive response of the gut-brain pathway to a high fat diet. Immunochemical detection of Fos protein was used as a measure of neuronal activation in the nucleus of the solitary tract (NTS) in response to intragastric administration of lipid in DIO-P (C57Bl6) and DIO-R (129sv) mouse strains maintained on chow or high fat, high energy diets (45% or 60% kcal from fat). Intragastric lipid administration activated neurons in the NTS in both DIO-P and DIO-R mice; the number of activated neurons was significantly greater in DIO-P than in DIO-R mice (P<0.001). However, lipid-induced activation of NTS neurons in DIO-P mice was attenuated by approximately 30% after maintenance on either 45% or 60% HF diet, for 4 or 8 weeks, compared to chow fed controls (P<0.05). In contrast, in DIO-R mice, maintenance on a HF diet (45% or 60%) had no effect on lipid-induced activation of NTS neurons. These results demonstrate that DIO-P and DIO-R mice strains differ in the adaptation of the pathway to long term ingestion of high fat diets, which may contribute to decrease satiation and increased food intake.
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Affiliation(s)
- Michael J Donovan
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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Wojnicki FHE, Johnson DS, Corwin RLW. Access conditions affect binge-type shortening consumption in rats. Physiol Behav 2008; 95:649-57. [PMID: 18851983 DOI: 10.1016/j.physbeh.2008.09.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 09/01/2008] [Accepted: 09/18/2008] [Indexed: 12/31/2022]
Abstract
When non-food-deprived rats are given intermittent access to certain substances, consumption of those substances is greater than when more frequent access is provided. The present study examined the effects of three different shortening access conditions on subsequent shortening intake in rats. Each of the three different shortening conditions lasted five weeks and was followed by a five-week period in which shortening access was limited by time (1 h of availability) on either an Intermittent (Monday, Wednesday, Friday) or Daily schedule of access. In Part 1, limiting the quantity of shortening provided during the 1-h period of availability attenuated subsequent 1-h shortening intake in the Intermittent access group, but had no statistically significant effect in the Daily access group. In Part 2, unrestricted availability of shortening (24 h/day-7 days/week) attenuated subsequent 1-h shortening intake in all groups. In Part 3, shortening non-availability for five weeks enhanced subsequent 1-h shortening intake in all groups. It was also shown that rats under an Intermittent, but not a Daily, schedule of access consumed as much shortening during a 1-h period of availability, as was consumed in 24 h when shortening availability was unrestricted. These results demonstrate that while intermittent access is necessary and sufficient to stimulate binge-type eating in rats, the behavioral history can modulate binge size.
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Affiliation(s)
- F H E Wojnicki
- The Pennsylvania State University, Nutritional Sciences Department, 126 S. Henderson, University Park, PA 16802, USA
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48
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Paulino G, Darcel N, Tome D, Raybould H. Adaptation of lipid-induced satiation is not dependent on caloric density in rats. Physiol Behav 2007; 93:930-6. [PMID: 18234246 DOI: 10.1016/j.physbeh.2007.12.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2007] [Revised: 12/13/2007] [Accepted: 12/19/2007] [Indexed: 01/15/2023]
Abstract
UNLABELLED Food intake is modulated by ingestive (gastrointestinal) and post-ingestive signals; ingested fat is potent to produce short-term satiety (satiation) but this can be modified by long-term ingestion of a high fat diet. AIM Determine whether altered lipid-induced satiation is dependent on the fat content of the diet, rather than increased caloric density or changes in adiposity. METHODS Initial experiments determined the differences in the microstructure of meal patterns in rats fed a high fat diet (HF: 38% fat kcal) and in rats pair-fed an isocaloric, isonitrogenous low fat diet (LF: 10% fat kcal) and changes in meal patterns measured after long-term maintenance on the HF diet. RESULTS Rats fed the HF diet had a significant 50% increase in meal frequency compared to rats fed the LF diet; in addition, there was a significant reduction in meal size (32%) and inter meal interval (38%) consistent with induction of satiation. After 8 weeks on the HF diet, these parameters tend to approach those of rats maintained on the LF diet. There was a significant 56% decrease in the activation of neurons in the NTS in response to intragastric gavage of lipid in rats maintained for 8 weeks on the HF compared to LF diet. CONCLUSION Dietary fat alters meal patterns consistent with induction of a short-term satiety signal. This signal is attenuated with long-term exposure to dietary lipid, in the absence of ingestion of additional calories or changes in body weight. This adaptation of short-term satiety might contribute to diet-induced obesity.
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Affiliation(s)
- G Paulino
- Department Anatomy, Physiology and Cell Biology, UC Davis School of Veterinary Medicine, CA, USA
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49
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Buda-Levin A, Wojnicki FH, Corwin RL. Baclofen reduces fat intake under binge-type conditions. Physiol Behav 2005; 86:176-84. [PMID: 16140347 PMCID: PMC1769468 DOI: 10.1016/j.physbeh.2005.07.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Accepted: 07/06/2005] [Indexed: 12/22/2022]
Abstract
The GABA-B agonist baclofen reduces drug self-administration in rats and has shown promise clinically in the treatment of substance abuse. Baclofen generally does not reduce food intake in non-binge feeding protocols. In this study, baclofen was tested in a fat-binge protocol. Thirty male rats were divided into three groups (B: binge; FM: fat-matched; C: chow). B received a bowl of vegetable shortening for 2 h on Monday, Wednesday, and Friday (MWF) and continuous access to powdered chow (regular chow) in all phases. FM had continuous access to a regular chow+shortening mixture (FM chow) that provided the same proportion of shortening and regular chow that the B rats consumed in all phases. In addition, FM had the following: phase 1: no separate bowl of shortening; phase 2: 2-h MWF access to a separate bowl of shortening; phase 3, daily 2-h access to a separate bowl of shortening; C rats had continuous access to the regular chow in all phases. In addition, C had the following: phase 1: no separate bowl of shortening; phase 2: 2-h MWF access to a separate bowl of shortening; in phase 3, daily 2-h access to a separate bowl of shortening. Baclofen (1.0, 1.8 mg/kg, i.p.) reduced shortening intake regardless of access condition. Baclofen had no effect on, or stimulated, FM and regular chow intake. These results demonstrate that baclofen can reduce fat intake in rats under binge-type conditions. Furthermore, these results indicate that bingeing, as modeled in our protocol, is different from other forms of food intake and may share similarities with substance abuse.
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Affiliation(s)
| | | | - Rebecca L. Corwin
- * Corresponding author. Tel.: +1 814 865 6519; fax: +1 814 863 6103. E-mail address: (R.L. Corwin)
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50
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Savastano DM, Covasa M. Adaptation to a high-fat diet leads to hyperphagia and diminished sensitivity to cholecystokinin in rats. J Nutr 2005; 135:1953-9. [PMID: 16046722 DOI: 10.1093/jn/135.8.1953] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Rats fed high-fat (HF) diets exhibit reduced sensitivity to some peptide satiety signals. We hypothesized that reduced sensitivity to satiety signals might contribute to overconsumption of a high-energy food after adaptation to HF diets. To test this, we measured daily, 3-h intake of a high-energy, high-fat (HHF, 22.3 kJ/g) test food in rats fed either low-fat (LF) or HF, isoenergetic (16.2 kJ/g) diets. During testing, half of each group received the HHF test food (LF/HHF; HF/HHF), whereas the other half received their respective maintenance diet (LF/LF; HF/HF). Rats fed a HF diet ate more of the HHF food during the 3-h testing period than LF-fed rats (HF/HHF = 7.7 +/- 0.3 g vs. LF/HHF = 5.5 +/- 0.2 g; P = 0.003). Rats tested on their own maintenance diets had similar intakes (HF/HF = 3.2 +/- 0.2 g vs. LF/LF = 3.7 +/- 0.3 g), which were lower (P < or = 0.008) than intakes of rats tested on HHF. HHF-tested rats did not differ in body weight by the end of wk 2 of testing. In a subsequent short-term choice preference test, rats exhibited an equal relative preference for HHF irrespective of their maintenance diets (HF = 63.1%, LF = 68.1%, P = 0.29). Finally, we examined the effect of intraperitoneal NaCl or cholecystokinin (CCK)-8 (100 and 250 ng/kg) injection on 1-h food intake. Both doses of CCK significantly suppressed food intake in LF-fed rats but not HF-fed rats. These results demonstrate that chronic ingestion of a HF diet leads to short-term overconsumption of a high-energy, high-fat food compared with LF-fed cohorts, which is associated with a decreased sensitivity to CCK.
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Affiliation(s)
- David M Savastano
- Department of Nutritional Sciences, College of Health and Human Development, The Pennsylvania State University, University Park, 16802-6504, USA.
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