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Leal H, Carvalhas-Almeida C, Álvaro AR, Cavadas C. Modeling hypothalamic pathophysiology in vitro for metabolic, circadian, and sleep disorders. Trends Endocrinol Metab 2024; 35:505-517. [PMID: 38307813 DOI: 10.1016/j.tem.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 02/04/2024]
Abstract
The hypothalamus, a small and intricate brain structure, orchestrates numerous neuroendocrine functions through specialized neurons and nuclei. Disruption of this complex circuitry can result in various diseases, including metabolic, circadian, and sleep disorders. Advances in in vitro models and their integration with new technologies have significantly benefited research on hypothalamic function and pathophysiology. We explore existing in vitro hypothalamic models and address their challenges and limitations as well as translational findings. We also highlight how collaborative efforts among multidisciplinary teams are essential to develop relevant and translational experimental models capable of replicating intricate neural circuits and neuroendocrine pathways, thereby advancing our understanding of therapeutic targets and drug discovery in hypothalamus-related disorders.
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Affiliation(s)
- Helena Leal
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Center for Innovation in Biomedicine and Biotechnology (CIBB), University of Coimbra, Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Catarina Carvalhas-Almeida
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Center for Innovation in Biomedicine and Biotechnology (CIBB), University of Coimbra, Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Ana Rita Álvaro
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Center for Innovation in Biomedicine and Biotechnology (CIBB), University of Coimbra, Coimbra, Portugal
| | - Cláudia Cavadas
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Center for Innovation in Biomedicine and Biotechnology (CIBB), University of Coimbra, Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.
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2
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McIlwraith EK, Belsham DD. Palmitate alters miRNA content of small extracellular vesicles secreted from NPY/AgRP-expressing hypothalamic neurons. Brain Res 2023; 1810:148367. [PMID: 37054963 DOI: 10.1016/j.brainres.2023.148367] [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: 11/29/2022] [Revised: 04/02/2023] [Accepted: 04/09/2023] [Indexed: 04/15/2023]
Abstract
Exosomes (sEVs) are extracellular vesicles involved in the pathogenesis of obesity. Notably, exosomal microRNAs (miRNAs) have emerged as crucial mediators of communication between cells and are involved in the development of obesity. One region of the brain known to be dysregulated in obesity is the hypothalamus. It coordinates whole-body energy homeostasis through stimulation and inhibition of the orexigenic neuropeptide (NPY)/agouti-related peptide (AgRP) neurons and anorexigenic proopiomelanocortin (POMC) neurons. A role for hypothalamic astrocytic exosomes in communication with POMC neurons was previously elucidated. Yet, it was unknown whether NPY/AgRP neurons secreted exosomes. We previously established that the saturated fat palmitate alters the intracellular levels of miRNAs and we now questioned whether palmitate would also alter the miRNA content of exosomal miRNAs. We found that the mHypoE-46 cell line secreted particles consistent with the size of exosomes and that palmitate altered levels of a spectrum of miRNAs associated with exosomes. The predicted KEGG pathways of the collective miRNA predicted targets included fatty acid metabolism and insulin signaling. Of note, one of these altered secreted miRNAs was miR-2137, which was also altered within the cells. We also found that while sEVs collected from the mHypoE-46 neurons increased Pomc mRNA in the mHypoA-POMC/GFP-2 cells after 48 hours, the effect was absent with sEVs isolated following palmitate treatment, indicating another potential route by which palmitate promotes obesity. Hypothalamic neuronal exosomes may therefore play a role in the control of energy homeostasis that may be disrupted in obese conditions.
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Affiliation(s)
- Emma K McIlwraith
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8
| | - Denise D Belsham
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8; Departments of Medicine and Obstetrics and Gynaecology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada.
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3
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McIlwraith EK, Belsham DD. Palmitate alters miR-2137 and miR-503-5p to induce orexigenic Npy in hypothalamic neuronal cell models: Rescue by oleate and docosahexaenoic acid. J Neuroendocrinol 2023; 35:e13271. [PMID: 37208960 DOI: 10.1111/jne.13271] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 03/29/2023] [Accepted: 03/30/2023] [Indexed: 05/21/2023]
Abstract
MicroRNAs (miRNAs) are short noncoding RNA implicated in the pathogenesis of obesity. One cause of obesity is excess exposure to the saturated fatty acid palmitate that can alter miRNA levels in the periphery. Palmitate also promotes obesity by acting on the hypothalamus, the central coordinator of energy homeostasis, to dysregulate hypothalamic feeding neuropeptides and induce ER stress and inflammatory signaling. We hypothesized that palmitate would alter hypothalamic miRNAs that control genes involved in energy homeostasis thereby contributing to the obesity-promoting effects of palmitate. We found that palmitate upregulated 20 miRNAs and downregulated six miRNAs in the orexigenic NPY/AgRP-expressing mHypoE-46 cell line. We focused on delineating the roles of miR-2137 and miR-503-5p, as they were strongly up- and downregulated by palmitate, respectively. Overexpression of miR-2137 increased Npy mRNA levels and downregulated Esr1 levels, while increasing C/ebpβ and Atf3 mRNA. Inhibiting miR-2137 had the opposite effect, except on Npy, which was unchanged. The most downregulated miRNA by palmitate, miR-503-5p, negatively regulated Npy mRNA levels. Exposure to the unsaturated fatty acids oleate or docosahexaenoic acid completely or partially blocked the effects of palmitate on miR-2137 and miR-503-5p as well as Npy, Agrp, Esr1, C/ebpβ and Atf3. MicroRNAs may therefore contribute to palmitate actions in dysregulating NPY/AgRP neurons. Effectively combating the deleterious effects of palmitate is crucial to help prevent or reduce the impact of obesity.
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Affiliation(s)
- Emma K McIlwraith
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Denise D Belsham
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Departments of Medicine and Obstetrics and Gynecology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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Sato T, Sassone-Corsi P. Nutrition, metabolism, and epigenetics: pathways of circadian reprogramming. EMBO Rep 2022; 23:e52412. [PMID: 35412705 PMCID: PMC9066069 DOI: 10.15252/embr.202152412] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 10/28/2021] [Accepted: 03/30/2022] [Indexed: 01/07/2023] Open
Abstract
Food intake profoundly affects systemic physiology. A large body of evidence has indicated a link between food intake and circadian rhythms, and ~24-h cycles are deemed essential for adapting internal homeostasis to the external environment. Circadian rhythms are controlled by the biological clock, a molecular system remarkably conserved throughout evolution. The circadian clock controls the cyclic expression of numerous genes, a regulatory program common to all mammalian cells, which may lead to various metabolic and physiological disturbances if hindered. Although the circadian clock regulates multiple metabolic pathways, metabolic states also provide feedback on the molecular clock. Therefore, a remarkable feature is reprogramming by nutritional challenges, such as a high-fat diet, fasting, ketogenic diet, and caloric restriction. In addition, various factors such as energy balance, histone modifications, and nuclear receptor activity are involved in the remodeling of the clock. Herein, we review the interaction of dietary components with the circadian system and illustrate the relationships linking the molecular clock to metabolism and critical roles in the remodeling process.
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Affiliation(s)
- Tomoki Sato
- Department of Biological Chemistry, Center for Epigenetics and Metabolism, School of Medicine, INSERM U1233, University of California, Irvine, CA, USA
| | - Paolo Sassone-Corsi
- Department of Biological Chemistry, Center for Epigenetics and Metabolism, School of Medicine, INSERM U1233, University of California, Irvine, CA, USA
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Lieu CV, Loganathan N, Belsham DD. Mechanisms Driving Palmitate-Mediated Neuronal Dysregulation in the Hypothalamus. Cells 2021; 10:3120. [PMID: 34831343 PMCID: PMC8617942 DOI: 10.3390/cells10113120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 12/17/2022] Open
Abstract
The hypothalamus maintains whole-body homeostasis by integrating information from circulating hormones, nutrients and signaling molecules. Distinct neuronal subpopulations that express and secrete unique neuropeptides execute the individual functions of the hypothalamus, including, but not limited to, the regulation of energy homeostasis, reproduction and circadian rhythms. Alterations at the hypothalamic level can lead to a myriad of diseases, such as type 2 diabetes mellitus, obesity, and infertility. The excessive consumption of saturated fatty acids can induce neuroinflammation, endoplasmic reticulum stress, and resistance to peripheral signals, ultimately leading to hyperphagia, obesity, impaired reproductive function and disturbed circadian rhythms. This review focuses on the how the changes in the underlying molecular mechanisms caused by palmitate exposure, the most commonly consumed saturated fatty acid, and the potential involvement of microRNAs, a class of non-coding RNA molecules that regulate gene expression post-transcriptionally, can result in detrimental alterations in protein expression and content. Studying the involvement of microRNAs in hypothalamic function holds immense potential, as these molecular markers are quickly proving to be valuable tools in the diagnosis and treatment of metabolic disease.
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Affiliation(s)
- Calvin V. Lieu
- Department of Physiology, University of Toronto, Medical Sciences Building 3247A, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada; (C.V.L.); (N.L.)
| | - Neruja Loganathan
- Department of Physiology, University of Toronto, Medical Sciences Building 3247A, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada; (C.V.L.); (N.L.)
| | - Denise D. Belsham
- Department of Physiology, University of Toronto, Medical Sciences Building 3247A, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada; (C.V.L.); (N.L.)
- Departments of Obstetrics/Gynecology and Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
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Guo X, Zheng J, Zhang S, Jiang X, Chen T, Yu J, Wang S, Ma X, Wu C. Advances in Unhealthy Nutrition and Circadian Dysregulation in Pathophysiology of NAFLD. FRONTIERS IN CLINICAL DIABETES AND HEALTHCARE 2021; 2:691828. [PMID: 36994336 PMCID: PMC10012147 DOI: 10.3389/fcdhc.2021.691828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 09/27/2021] [Indexed: 11/13/2022]
Abstract
Unhealthy diets and lifestyle result in various metabolic conditions including metabolic syndrome and non-alcoholic fatty liver disease (NAFLD). Much evidence indicates that disruption of circadian rhythms contributes to the development and progression of excessive hepatic fat deposition and inflammation, as well as liver fibrosis, a key characteristic of non-steatohepatitis (NASH) or the advanced form of NAFLD. In this review, we emphasize the importance of nutrition as a critical factor in the regulation of circadian clock in the liver. We also focus on the roles of the rhythms of nutrient intake and the composition of diets in the regulation of circadian clocks in the context of controlling hepatic glucose and fat metabolism. We then summarize the effects of unhealthy nutrition and circadian dysregulation on the development of hepatic steatosis and inflammation. A better understanding of how the interplay among nutrition, circadian rhythms, and dysregulated metabolism result in hepatic steatosis and inflammation can help develop improved preventive and/or therapeutic strategies for managing NAFLD.
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Affiliation(s)
- Xin Guo
- Department of Nutrition and Food Hygiene, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China
- *Correspondence: Xin Guo, ; Chaodong Wu,
| | - Juan Zheng
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Provincial Clinical Research Center for Diabetes and Metabolic Disorders, Wuhan, China
| | - Shixiu Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Xiaofan Jiang
- Department of Nutrition and Food Hygiene, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Ting Chen
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Provincial Clinical Research Center for Diabetes and Metabolic Disorders, Wuhan, China
| | - Jiayu Yu
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Provincial Clinical Research Center for Diabetes and Metabolic Disorders, Wuhan, China
| | - Shu'e Wang
- Department of Nutrition and Food Hygiene, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Xiaomin Ma
- Department of Nutrition and Food Hygiene, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Chaodong Wu
- Department of Nutrition, Texas A&M University, College Station, TX, United States
- *Correspondence: Xin Guo, ; Chaodong Wu,
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Martchenko A, Brubaker PL. Effects of Obesogenic Feeding and Free Fatty Acids on Circadian Secretion of Metabolic Hormones: Implications for the Development of Type 2 Diabetes. Cells 2021; 10:cells10092297. [PMID: 34571945 PMCID: PMC8466112 DOI: 10.3390/cells10092297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 08/27/2021] [Accepted: 08/30/2021] [Indexed: 11/19/2022] Open
Abstract
Circadian rhythms are 24-h internal biological rhythms within organisms that govern virtually all aspects of physiology. Interestingly, metabolic tissues have been found to express cell-autonomous clocks that govern their rhythmic activity throughout the day. Disruption of normal circadian rhythmicity, as induced by environmental factors such as shift work, significantly increases the risk for the development of metabolic diseases, including type 2 diabetes and obesity. More recently, obesogenic feeding and its fatty acid components have also been shown to be potent disruptors of normal circadian biology. Two key hormones that are released in response to nutrient intake are the anti-diabetic incretin hormone glucagon-like peptide-1, from intestinal L cells, and insulin secreted by pancreatic β cells, both of which are required for the maintenance of metabolic homeostasis. This review will focus on the circadian function of the L and β cells and how both obesogenic feeding and the saturated fatty acid, palmitate, affect their circadian clock and function. Following introduction of the core biological clock and the hierarchical organization of the mammalian circadian system, the circadian regulation of normal L and β cell function and the importance of GLP-1 and insulin in establishing metabolic control are discussed. The central focus of the review then considers the circadian-disrupting effects of obesogenic feeding and palmitate exposure in L and β cells, while providing insight into the potential causative role in the development of metabolic disease.
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Affiliation(s)
| | - Patricia Lee Brubaker
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada;
- Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
- Correspondence:
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Schmidt CX, Tsang AH, Oster H. Generation of Mouse Primary Hypothalamic Neuronal Cultures for Circadian Bioluminescence Assays. Bio Protoc 2021; 11:e3944. [PMID: 33796618 DOI: 10.21769/bioprotoc.3944] [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: 10/30/2020] [Revised: 01/11/2021] [Accepted: 01/31/2021] [Indexed: 11/02/2022] Open
Abstract
An endogenous circadian clock system enables organisms to adapt to time-of-day dependent environmental changes. In consequence, most physiological processes exhibit daily rhythms of, e.g., energy metabolism, immune function, sleep, or hormone production. Hypothalamic circadian clocks have been identified to play a particular role in coordinating many of these processes. Primary neuronal cultures are widely used as a physiologically relevant model to study molecular events within neurons. However, as circadian rhythms include dynamic molecular changes over longer timescales that vary between individual cells, longitudinal measurement methods are essential to investigate the regulation of circadian clocks of hypothalamic neurons. Here we provide a protocol for generating primary hypothalamic neuronal cultures expressing a circadian luciferase reporter. Such reporter cells can be used to longitudinally monitor cellular circadian rhythms at high temporal resolution by performing bioluminescence measurements.
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Affiliation(s)
- Cosima X Schmidt
- Institute of Neurobiology, Center of Brain, Behavior and Metabolism, University of Lübeck, Lübeck, Germany
| | - Anthony H Tsang
- Institute of Neurobiology, Center of Brain, Behavior and Metabolism, University of Lübeck, Lübeck, Germany
| | - Henrik Oster
- Institute of Neurobiology, Center of Brain, Behavior and Metabolism, University of Lübeck, Lübeck, Germany
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Michael NJ, Watt MJ. Long Chain Fatty Acids Differentially Regulate Sub-populations of Arcuate POMC and NPY Neurons. Neuroscience 2020; 451:164-173. [PMID: 33002557 DOI: 10.1016/j.neuroscience.2020.09.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 09/09/2020] [Accepted: 09/21/2020] [Indexed: 02/07/2023]
Abstract
Long chain fatty acids (LCFAs) have been suggested to influence the activity of hypothalamic neurons, however, limited studies have attempted to identify the neurochemical phenotype of these neurons. We aimed to determine if physiological levels of LCFAs alter the electrical excitability of pro-opiomelanocortin (POMC) and neuropeptide Y (NPY) neurons in the arcuate nucleus of the hypothalamus. We utilised whole-cell patch-clamp electrophysiology on brain slice preparations from genetic mouse models where green fluorescent protein was expressed in either POMC or NPY expressing cells. All animals had undergone an overnight fast to replicate conditions in which fatty acids would usually increase. Bath application of LCFAs were found to predominantly inhibit POMC neurons and predominantly excite NPY neurons. Differences between oleic and palmitic acid were not observed. These results suggest that LCFAs in the cerebrospinal fluid exert an underlying orexigenic tone to key hypothalamic neurons known to regulate energy homeostasis.
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Affiliation(s)
- Natalie J Michael
- Metabolic Disease, Obesity and Diabetes Program, Biomedicine Discovery Institute and the Department of Physiology, Monash University, Clayton 3800, VIC, Australia; Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City G1V4G5, Québec, Canada.
| | - Matthew J Watt
- Department of Physiology, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne 3010, VIC, Australia
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Tran A, He W, Jiang N, Chen JTC, Belsham DD. NAMPT and BMAL1 Are Independently Involved in the Palmitate-Mediated Induction of Neuroinflammation in Hypothalamic Neurons. Front Endocrinol (Lausanne) 2020; 11:351. [PMID: 32595600 PMCID: PMC7303266 DOI: 10.3389/fendo.2020.00351] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 05/05/2020] [Indexed: 12/19/2022] Open
Abstract
Obesity is a prominent metabolic disease that predisposes individuals to multiple comorbidities, including type 2 diabetes mellitus, cardiovascular diseases, and cancer. Elevated circulating levels of fatty acids contribute to the development of obesity, in part, by targeting the hypothalamus. Palmitate, the most abundant circulating saturated fatty acid, has been demonstrated to dysregulate NAMPT and circadian clock proteins, as well as induce neuroinflammation. These effects ultimately result in hypothalamic dysregulation of feeding behavior and energy homeostasis. NAMPT is the rate-limiting enzyme of the NAD+ salvage pathway and its expression is under the control of the circadian clock. NAD+ produced from NAMPT can modulate the circadian clock, demonstrating bidirectional interactions between circadian and metabolic pathways. Using NPY/AgRP-expressing mHypoE-46 neurons as well as the novel mHypoA-BMAL1-WT/F and mHypoA-BMAL1-KO/F cell lines, we studied whether there were any interactions between NAMPT and the core circadian clock protein BMAL1 in the palmitate-mediated induction of neuroinflammation. We report that palmitate altered Nampt, Bmal1, Per2 and the inflammatory genes Nf-κb, IκBα, Il-6, and Tlr4. Contrary to studies performed with peripheral tissues, the palmitate-mediated induction in Nampt was independent of BMAL1, and basal Nampt levels did not appear to exhibit rhythmic expression. Palmitate-induced downregulation of Bmal1 and Per2 was independent of NAMPT. However, NAMPT and BMAL1 were both involved in the regulation of Nf-κb, IκBα, Il-6, and Tlr4, as NAMPT inhibition resulted in the repression of basal Nf-κb and IκBα and normalized palmitate-mediated increases in Il-6, and Tlr4. On the other hand, BMAL1 deletion repressed basal Nf-κb, but increased basal Il-6. We conclude that NAMPT and BMAL1 do not interact at the transcriptional level in hypothalamic neurons, but are independently involved in the expression of inflammatory genes.
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Affiliation(s)
- Andy Tran
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Wenyuan He
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Nan Jiang
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Jim T. C. Chen
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Denise D. Belsham
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Medicine, University of Toronto, Toronto, ON, Canada
- Department of Obstetrics and Gynaecology, University of Toronto, Toronto, ON, Canada
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11
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Clemenzi MN, Martchenko A, Loganathan N, Tse EK, Brubaker PL, Belsham DD. Analysis of Western diet, palmitate and BMAL1 regulation of neuropeptide Y expression in the murine hypothalamus and BMAL1 knockout cell models. Mol Cell Endocrinol 2020; 507:110773. [PMID: 32114021 DOI: 10.1016/j.mce.2020.110773] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 02/19/2020] [Accepted: 02/24/2020] [Indexed: 12/20/2022]
Abstract
Western diets that are high in saturated fat and sugar disrupt circadian rhythms, induce weight gain, and lead to metabolic diseases including obesity. However, the mechanistic link between altered circadian rhythms and energy homeostasis remains poorly understood. In C57BL/6J mice, consuming a Western diet for 16 weeks significantly reduced food intake (at zeitgeber 12-16), in association with decreases in hypothalamic expression of the orexigenic neuropeptides, neuropeptide Y (Npy) and agouti-related peptide (AgRP). To examine the acute effects of the most prevalent saturated fatty acid in a Western diet, palmitate, and the role of the core clock gene, Bmal1, in the regulation of hypothalamic feeding neuropeptides, we used heterogeneous and clonal BMAL1 knockout (KO) immortalized hypothalamic cell lines, expressing specific neuropeptides, derived from male (M) and female (F) mice. Both mHypoA-BMAL1-KO/F and mHypoA-BMAL1-KO/M cells demonstrated a loss of circadian rhythmicity in expression of the clock gene, Per2, as compared to wild-type (control) cultures. Loss of BMAL1 also altered the time-dependent expression of Npy and proopiomelanocortin, and disrupted AgRP rhythmicity. Furthermore, palmitate increased BMAL1 binding to the Npy promotor region, and palmitate treatment (50 μM for 24 h) stimulated Npy expression in a BMAL1-dependent manner in both heterogeneous and clonal NPY-expressing female-derived cell models. The results of this study demonstrate that circadian expression of Bmal1 serves as a mechanistic link between Western diet- and palmitate-induced disruptions of the normal rhythmic patterns in hypothalamic feeding-related neuropeptides.
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Affiliation(s)
| | | | - Neruja Loganathan
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Erika K Tse
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Patricia L Brubaker
- Department of Physiology, University of Toronto, Toronto, ON, Canada; Department of Medicine, University of Toronto, Toronto, ON, Canada
| | - Denise D Belsham
- Department of Physiology, University of Toronto, Toronto, ON, Canada; Department of Medicine, University of Toronto, Toronto, ON, Canada; Department of Obstetrics and Gynaecology, University of Toronto, Toronto, ON, Canada.
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12
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Ruiz-Gayo M, Olmo ND. Interaction Between Circadian Rhythms, Energy Metabolism, and Cognitive Function. Curr Pharm Des 2020; 26:2416-2425. [PMID: 32156228 DOI: 10.2174/1381612826666200310145006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 02/11/2020] [Indexed: 11/22/2022]
Abstract
The interaction between meal timing and light regulates circadian rhythms in mammals and not only determines the sleep-wake pattern but also the activity of the endocrine system. Related with that, the necessity to fulfill energy needs is a driving force that requires the participation of cognitive skills whose performance has been shown to undergo circadian variations. These facts have led to the concept that cognition and feeding behaviour can be analysed from a chronobiological perspective. In this context, research carried out during the last two decades has evidenced the link between feeding behaviour/nutritional habits and cognitive processes, and has highlighted the impact of circadian disorders on cognitive decline. All that has allowed hypothesizing a tight relationship between nutritional factors, chronobiology, and cognition. In this connection, experimental diets containing elevated amounts of fat and sugar (high-fat diets; HFDs) have been shown to alter in rodents the circadian distribution of meals, and to have a negative impact on cognition and motivational aspects of behaviour that disappear when animals are forced to adhere to a standard temporal eating pattern. In this review, we will present relevant studies focussing on the effect of HFDs on cognitive aspects of behaviour, paying particular attention to the influence that chronobiological alterations caused by these diets may have on hippocampaldependent cognition.
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Affiliation(s)
- Mariano Ruiz-Gayo
- Department of Health and Pharmaceutical Sciences, School of Pharmacy, Universidad San Pablo-CEU, CEU Universities, Madrid, Spain
| | - Nuria D Olmo
- Department of Health and Pharmaceutical Sciences, School of Pharmacy, Universidad San Pablo-CEU, CEU Universities, Madrid, Spain
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13
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Haynes VR, Michael NJ, van den Top M, Zhao FY, Brown RD, De Souza D, Dodd GT, Spanswick D, Watt MJ. A Neural basis for Octanoic acid regulation of energy balance. Mol Metab 2020; 34:54-71. [PMID: 32180560 PMCID: PMC7011014 DOI: 10.1016/j.molmet.2020.01.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 12/11/2019] [Accepted: 01/03/2020] [Indexed: 12/13/2022] Open
Abstract
Objectives Nutrient sensing by hypothalamic neurons is critical for the regulation of food intake and energy expenditure. We aimed to identify long- and medium-chain fatty acid species transported into the brain, their effects on energy balance, and the mechanisms by which they regulate activity of hypothalamic neurons. Methods Simultaneous blood and cerebrospinal fluid (CSF) sampling was undertaken in rats and metabolic analyses using radiolabeled fatty acid tracers were performed on mice. Electrophysiological recording techniques were used to investigate signaling mechanisms underlying fatty acid-induced changes in activity of pro-opiomelanocortin (POMC) neurons. Results Medium-chain fatty acid (MCFA) octanoic acid (C8:0), unlike long-chain fatty acids, was rapidly transported into the hypothalamus of mice and almost exclusively oxidized, causing rapid, transient reductions in food intake and increased energy expenditure. Octanoic acid differentially regulates the excitability of POMC neurons, activating these neurons directly via GPR40 and inducing inhibition via an indirect non-synaptic, purine, and adenosine receptor-dependent mechanism. Conclusions MCFA octanoic acid is a central signaling nutrient that targets POMC neurons via distinct direct and indirect signal transduction pathways to instigate changes in energy status. These results could explain the beneficial health effects that accompany MCFA consumption. Octanoic acid (C8:0) is rapidly transported from blood to the cerebrospinal fluid. Octanoic acid rapidly reduces food intake and increases energy expenditure. Octanoic acid targets POMC neurons through direct and indirect signaling pathways. Activation of POMC neurons occurs directly through GPR40. Inhibition occurs through a nonsynaptic, purine and adenosine receptor-dependent mechanism.
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Affiliation(s)
- Vanessa R Haynes
- Department of Physiology, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, 3010, VIC, Australia; Metabolic Disease, Obesity and Diabetes Program, Biomedicine Discovery Institute and the Department of Physiology, Monash University, Clayton, 3800, VIC, Australia
| | - Natalie J Michael
- Metabolic Disease, Obesity and Diabetes Program, Biomedicine Discovery Institute and the Department of Physiology, Monash University, Clayton, 3800, VIC, Australia; Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, 75390, USA
| | | | | | - Russell D Brown
- Metabolic Disease, Obesity and Diabetes Program, Biomedicine Discovery Institute and the Department of Physiology, Monash University, Clayton, 3800, VIC, Australia
| | - David De Souza
- Metabolomics Australia, Bio21 Institute, University of Melbourne, Parkville, 3010, VIC, Australia
| | - Garron T Dodd
- Department of Physiology, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, 3010, VIC, Australia
| | - David Spanswick
- Metabolic Disease, Obesity and Diabetes Program, Biomedicine Discovery Institute and the Department of Physiology, Monash University, Clayton, 3800, VIC, Australia; Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK; NeuroSolutions Ltd, Coventry, UK.
| | - Matthew J Watt
- Department of Physiology, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, 3010, VIC, Australia.
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14
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Tal Y, Chapnik N, Froy O. Non-obesogenic doses of palmitate disrupt circadian metabolism in adipocytes. Adipocyte 2019; 8:392-400. [PMID: 31791161 PMCID: PMC6948973 DOI: 10.1080/21623945.2019.1698791] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 11/07/2019] [Accepted: 11/25/2019] [Indexed: 01/06/2023] Open
Abstract
Saturated fatty acids, such as palmitate, lead to circadian disruption. We aimed at studying the effect of low doses of palmitate on circadian metabolism and to decipher the mechanism by which fatty acids convey their effect in adipocytes. Mice were fed non-obesogenic doses of palm or olive oil and adipocytes were treated with palmitate and oleate. Cultured adipocytes treated with oleate showed increased AMPK activity and induced the expression of mitochondrial genes indicating increased fatty acid oxidation, while palmitate increased ACC activity and induced the expression of lipogenic genes, indicating increased fatty acid synthesis. Low doses of palmitate were sufficient to alter circadian rhythms, due to changes in the expression and/or activity of key metabolic proteins including GSK3β and AKT. Palmitate-induced AKT and GSK3β activation led to the phosphorylation of BMAL1 that resulted in low levels as well as high amplitude of circadian clock expression. In adipocytes, the detrimental metabolic alteration of palmitate manifests itself early on even at non-obesogenic levels. This is accompanied by modulating BMAL1 expression and phosphorylation levels, which lead to dampened clock gene expression.
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Affiliation(s)
- Yael Tal
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Nava Chapnik
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Oren Froy
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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15
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Park S, Oh TS, Kim S, Kim EK. Palmitate-induced autophagy liberates monounsaturated fatty acids and increases Agrp expression in hypothalamic cells. Anim Cells Syst (Seoul) 2019; 23:384-391. [PMID: 31853375 PMCID: PMC6913639 DOI: 10.1080/19768354.2019.1696407] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 11/15/2019] [Indexed: 12/13/2022] Open
Abstract
Fatty acids regulate food intake, although the exact mechanism remains unknown. Emerging evidence suggests that intracellular free fatty acids generated by starvation-induced autophagy regulate food intake. Starvation for 6 h elevated fatty acids such as palmitate, oleate, arachidonate, eicosatrienoate, and docosahexaenoate in the mouse serum. Among them, palmitate induced lipophagy, an autophagic degradation of cellular lipid droplets, in agouti-related peptide (Agrp)-expressing hypothalamic cells. Palmitate-induced lipophagy increased both Agrp expression and the contents of monounsaturated fatty acids such as palmitoleate, oleate, and (E)-9-octadecanoate, whereas these effects were blunted by autophagy deficiency. These findings support the role of free fatty acids in hypothalamic autophagy that regulates the appetite by changing the expression of orexigenic neuropeptides.
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Affiliation(s)
- Seokjae Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea.,Neurometabolomics Research Center, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea
| | - Tae Seok Oh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea
| | - Seolsong Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea
| | - Eun-Kyoung Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea.,Neurometabolomics Research Center, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea
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16
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Le Foll C. Hypothalamic Fatty Acids and Ketone Bodies Sensing and Role of FAT/CD36 in the Regulation of Food Intake. Front Physiol 2019; 10:1036. [PMID: 31474875 PMCID: PMC6702519 DOI: 10.3389/fphys.2019.01036] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/29/2019] [Indexed: 12/19/2022] Open
Abstract
The obesity and type-2 diabetes epidemic is escalating and represents one of the costliest biomedical challenges confronting modern society. Moreover, the increasing consumption of high fat food is often correlated with an increase in body mass index. In people predisposed to be obese or already obese, the impaired ability of the brain to monitor and respond to alterations in fatty acid (FA) metabolism is increasingly recognized as playing a role in the pathophysiological development of these disorders. The brain senses and regulates metabolism using highly specialized nutrient-sensing neurons located mainly in the hypothalamus. The same neurons are able to detect variation in the extracellular levels of glucose, FA and ketone bodies as a way to monitor nutrient availability and to alter its own activity. In addition, glial cells such as astrocytes create major connections to neurons and form a tight relationship to closely regulate nutrient uptake and metabolism. This review will examine the different pathways by which neurons are able to detect free fatty acids (FFA) to alter its activity and how high fat diet (HFD)-astrocytes induced ketone bodies production interplays with neuronal FA sensing. The role of HFD-induced inflammation and how FA modulate the reward system will also be investigated here.
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Affiliation(s)
- Christelle Le Foll
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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17
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Abstract
Feeding, which is essential for all animals, is regulated by homeostatic mechanisms. In addition, food consumption is temporally coordinated by the brain over the circadian (~24 h) cycle. A network of circadian clocks set daily windows during which food consumption can occur. These daily windows mostly overlap with the active phase. Brain clocks that ensure the circadian control of food intake include a master light-entrainable clock in the suprachiasmatic nuclei of the hypothalamus and secondary clocks in hypothalamic and brainstem regions. Metabolic hormones, circulating nutrients and visceral neural inputs transmit rhythmic cues that permit (via close and reciprocal molecular interactions that link metabolic processes and circadian clockwork) brain and peripheral organs to be synchronized to feeding time. As a consequence of these complex interactions, growing evidence shows that chronodisruption and mistimed eating have deleterious effects on metabolic health. Conversely, eating, even eating an unbalanced diet, during the normal active phase reduces metabolic disturbances. Therefore, in addition to energy intake and dietary composition, appropriately timed meal patterns are critical to prevent circadian desynchronization and limit metabolic risks. This Review provides insight into the dual modulation of food intake by homeostatic and circadian processes, describes the mechanisms regulating feeding time and highlights the beneficial effects of correctly timed eating, as opposed to the negative metabolic consequences of mistimed eating.
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Affiliation(s)
- Etienne Challet
- Circadian clocks and metabolism team, Institute of Cellular and Integrative Neurosciences, Centre National de la Recherche Scientifique (CNRS), University of Strasbourg, Strasbourg, France.
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18
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Tal Y, Chapnik N, Froy O. Non-obesogenic doses of fatty acids modulate the functionality of the circadian clock in the liver. Cell Mol Life Sci 2019; 76:1795-1806. [PMID: 30694347 PMCID: PMC11105771 DOI: 10.1007/s00018-019-03023-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 01/01/2019] [Accepted: 01/22/2019] [Indexed: 12/19/2022]
Abstract
Saturated fatty acids, such as palmitate, lead to circadian disruption in cell culture. Moreover, information regarding the effects of unsaturated fatty acids on circadian parameters is scarce. We aimed at studying the effects of low doses of saturated as well as unsaturated fatty acids on circadian metabolism in vivo and at deciphering the mechanism by which fatty acids convey their effect. Mice were fed non-obesogenic doses of palm or olive oil and hepatocytes were treated with palmitate and oleate. Mice fed non-obesogenic doses of palm oil showed increased signaling towards fatty acid synthesis, while olive oil increased signaling towards fatty acid oxidation. Low doses of palmitate and oleate were sufficient to alter circadian rhythms, due to changes in the expression and/or activity of key metabolic proteins. Palmitate, but not oleate, counteracted the reduction in lipid accumulation and BMAL1-induced expression of mitochondrial genes involved in fatty acid oxidation. Palmitate was also found to interfere with the transcriptional activity of CLOCK:BMAL1 by preventing BMAL1 deacetylation and activation. In addition, palmitate, but not oleate, reduced PER2-mediated transcriptional activation and increased REV-ERBα-mediated transcriptional inhibition of Bmal1. The inhibition of PER2-mediated transcriptional activation by palmitate was achieved by interfering with PER2 nuclear translocation. Indeed, PER2 reduced fat accumulation in hepatocytes and this reduction was prevented by palmitate. Herein, we show that the detrimental metabolic alteration seen with high doses of palmitate manifests itself early on even with non-obesogenic levels. This is achieved by modulating BMAL1 at several levels abrogating its activity and expression.
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Affiliation(s)
- Yael Tal
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, 76100, Rehovot, Israel
| | - Nava Chapnik
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, 76100, Rehovot, Israel
| | - Oren Froy
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, 76100, Rehovot, Israel.
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19
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Loganathan N, Salehi A, Chalmers JA, Belsham DD. Bisphenol A Alters Bmal1, Per2, and Rev-Erba mRNA and Requires Bmal1 to Increase Neuropeptide Y Expression in Hypothalamic Neurons. Endocrinology 2019; 160:181-192. [PMID: 30500912 PMCID: PMC6307099 DOI: 10.1210/en.2018-00881] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 11/27/2018] [Indexed: 12/17/2022]
Abstract
Bisphenol A (BPA), a ubiquitous environmental endocrine disruptor, is considered an obesogen. However, its role in the hypothalamic control of energy balance remains largely unexplored. Because disruption of the circadian clock is tightly associated with metabolic consequences, we explored how BPA affects the components of the molecular circadian clock in the feeding-related neurons of the hypothalamus. In immortalized POMC and NPY/AgRP-expressing hypothalamic cell lines and primary culture, we describe how BPA significantly alters mRNA expression of circadian clock genes Bmal1,Per2, and Rev-Erbα. Furthermore, we use newly generated Bmal1-knockout (KO) hypothalamic cell lines to link the BPA-induced neuropeptide dysregulation to the molecular clock. Specifically, BPA increased Npy, Agrp, and Pomc mRNA expression in wild type hypothalamic cells, whereas the increase in Npy, but not Agrp or Pomc, was abolished in cell lines lacking BMAL1. In line with this increase, BPA led to increased BMAL1 binding to the Npy promotor, potentially increasing Npy transcription. In conclusion, we show that BPA-mediated dysregulation of the circadian molecular clock is linked to the deleterious effects of BPA on neuropeptide expression. Furthermore, we describe hypothalamic Bmal1-KO cell lines to study the role of BMAL1 in hypothalamic responses to metabolic, hormonal, and environmental factors.
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Affiliation(s)
- Neruja Loganathan
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Ashkan Salehi
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | | | - Denise D Belsham
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Obstetrics and Gynaecology, University of Toronto, Toronto, Ontario, Canada
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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20
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Clemenzi MN, Wellhauser L, Aljghami ME, Belsham DD. Tumour necrosis factor α induces neuroinflammation and insulin resistance in immortalised hypothalamic neurones through independent pathways. J Neuroendocrinol 2019; 31:e12678. [PMID: 30582235 DOI: 10.1111/jne.12678] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Revised: 11/26/2018] [Accepted: 12/05/2018] [Indexed: 12/27/2022]
Abstract
The links between obesity, inflammation and insulin resistance, which are all key characteristics of type 2 diabetes mellitus, are yet to be delineated in the brain. One of the key neuroinflammatory proteins detected in the hypothalamus with over-nutrition is tumour necrosis factor (TNF)α. Using immortalised embryonic rat and mouse hypothalamic cell lines (rHypoE-7 and mHypoE-46) that express orexigenic neuropeptide Y and agouti-related peptide, we investigated changes in insulin signalling and inflammatory gene marker mRNA expression after TNFα exposure. A quantitative polymerase chain reaction array of 84 inflammatory markers (cytokines, chemokines and receptors) demonstrated an increase in the expression of multiple genes encoding inflammatory markers upon exposure to 100 ng mL-1 TNFα for 4 hours. Furthermore, neurones pre-exposed to TNFα (50 ng mL-1 ) for 6 or 16 hours exhibited a significant reduction in phosphorylated Akt compared to control after insulin treatment, indicating the attenuation of insulin signalling. mRNA expression of insulin signalling-related genes was also decreased with exposure to TNFα. TNFα significantly increased mRNA expression of IκBα, Tnfrsf1a and IL6 at 4 and 24 hours, activating a pro-inflammatory state. An inhibitor study using an inhibitor of nuclear factor kappa B kinase subunit β (IKK-β) inhibitor, PS1145, demonstrated that TNFα-induced neuroinflammatory marker expression occurs through the IKK-β/nuclear factor-kappa B pathway, whereas oleate, a monounsaturated fatty acid, had no effect on inflammatory markers. To test the efficacy of anti-inflammatory treatment to reverse insulin resistance, neurones were treated with TNFα and PS1145, which did not significantly restore the TNFα-induced changes in cellular insulin sensitivity, indicating that an alternative pathway may be involved. In conclusion, exposure to the inflammatory cytokine TNFα causes cellular insulin resistance and inflammation marker expression in the rHypoE-7 and mHypoE-46 neurones, consistent with effects seen with TNFα in peripheral tissues. It also mimics insulin- and palmitate-induced insulin resistance in hypothalamic neurones. The present study provides further evidence that altered central energy metabolism may be caused by obesity-induced cytokine expression.
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Affiliation(s)
| | - Leigh Wellhauser
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Makram E Aljghami
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Denise D Belsham
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Obstetrics and Gynaecology, University of Toronto, Toronto, ON, Canada
- Department of Medicine, University of Toronto, Toronto, ON, Canada
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21
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Christie S, Vincent AD, Li H, Frisby CL, Kentish SJ, O'Rielly R, Wittert GA, Page AJ. A rotating light cycle promotes weight gain and hepatic lipid storage in mice. Am J Physiol Gastrointest Liver Physiol 2018; 315:G932-G942. [PMID: 30188750 DOI: 10.1152/ajpgi.00020.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Processes involved in regulation of energy balance and intermediary metabolism are aligned to the light-dark cycle. Shift-work and high-fat diet (HFD)-induced obesity disrupt circadian rhythmicity and are associated with increased risk of nonalcoholic fatty liver disease. This study aimed to determine the effect of simulating shift work on hepatic lipid accumulation in lean and HFD mice. C57BL/6 mice fed a standard laboratory diet (SLD) or HFD for 4 wk were further allocated to a normal light (NL) cycle (lights on: 0600-1800) or rotating light (RL) cycle [3 days NL and 4 days reversed (lights on: 1800-0600) repeated] for 8 wk. Tissue was collected every 3 h beginning at 0600. HFD mice gained more weight than SLD mice, and RL mice gained more weight than NL mice. SLD-NL and HFD-NL mice, but not RL mice, were more active, had higher respiratory quotients, and consumed/expended more energy during the dark phase compared with the light phase. Blood glucose and plasma cholesterol and triglyceride concentrations were elevated in HFD and SLD-RL compared with SLD-NL mice. Hepatic glycogen was elevated in HFD compared with SLD mice. Hepatic triglycerides were elevated in SLD-RL and HFD mice compared with SLD-NL. Circadian rhythmicity of hepatic acetyl-CoA carboxylase (ACACA) mRNA was phase shifted in SLD-RL and HFD-NL and lost in HFD-RL mice. Hepatic ACACA protein was reduced in SLD-RL and HFD mice compared with SLD-NL mice. Hepatic adipose triglyceride lipase was elevated in HFD-NL compared with SLD-NL but lower in RL mice compared with NL mice irrespective of diet. In conclusion, an RL cycle model of shift work promotes weight gain and hepatic lipid storage even in lean conditions. NEW & NOTEWORTHY In this publication we describe the effects of a rotating light cycle model of shift work in lean and high-fat diet-induced obese mice on body mass, diurnal patterns of energy intake and expenditure, and hepatic lipid storage. The data indicate that modeling shift work, via a rotating light cycle, promotes weight gain and hepatic lipid accumulation even in mice on a standard laboratory diet.
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Affiliation(s)
- Stewart Christie
- Vagal Afferent Research Group, Centre for Nutrition and Gastrointestinal Disease, Adelaide Medical School, University of Adelaide , Adelaide, South Australia
| | - Andrew D Vincent
- Freemasons Foundation Centre for Men's Health, Adelaide Medical School, University of Adelaide , Adelaide, South Australia.,Nutrition and Metabolism, South Australian Health and Medical Research Institute , Adelaide, South Australia
| | - Hui Li
- Vagal Afferent Research Group, Centre for Nutrition and Gastrointestinal Disease, Adelaide Medical School, University of Adelaide , Adelaide, South Australia.,Nutrition and Metabolism, South Australian Health and Medical Research Institute , Adelaide, South Australia
| | - Claudine L Frisby
- Vagal Afferent Research Group, Centre for Nutrition and Gastrointestinal Disease, Adelaide Medical School, University of Adelaide , Adelaide, South Australia
| | - Stephen J Kentish
- Vagal Afferent Research Group, Centre for Nutrition and Gastrointestinal Disease, Adelaide Medical School, University of Adelaide , Adelaide, South Australia
| | - Rebecca O'Rielly
- Vagal Afferent Research Group, Centre for Nutrition and Gastrointestinal Disease, Adelaide Medical School, University of Adelaide , Adelaide, South Australia
| | - Gary A Wittert
- Vagal Afferent Research Group, Centre for Nutrition and Gastrointestinal Disease, Adelaide Medical School, University of Adelaide , Adelaide, South Australia.,Freemasons Foundation Centre for Men's Health, Adelaide Medical School, University of Adelaide , Adelaide, South Australia.,Nutrition and Metabolism, South Australian Health and Medical Research Institute , Adelaide, South Australia
| | - Amanda J Page
- Vagal Afferent Research Group, Centre for Nutrition and Gastrointestinal Disease, Adelaide Medical School, University of Adelaide , Adelaide, South Australia.,Nutrition and Metabolism, South Australian Health and Medical Research Institute , Adelaide, South Australia
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22
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Shpakov AO, Derkach KV. Molecular Mechanisms of the Effects of Metformin on the Functional Activity of Brain Neurons. ACTA ACUST UNITED AC 2018. [DOI: 10.1007/s11055-018-0657-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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23
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Tse EK, Belsham DD. Palmitate induces neuroinflammation, ER stress, and Pomc mRNA expression in hypothalamic mHypoA-POMC/GFP neurons through novel mechanisms that are prevented by oleate. Mol Cell Endocrinol 2018; 472:40-49. [PMID: 29180108 DOI: 10.1016/j.mce.2017.11.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/10/2017] [Accepted: 11/23/2017] [Indexed: 01/17/2023]
Abstract
Dietary fats can modulate brain function. How free fatty acids (FFAs) alter hypothalamic pro-opiomelanocortin (POMC) neurons remain undefined. The saturated FFA, palmitate, increased neuroinflammatory and ER stress markers, as well as Pomc mRNA levels, but did not affect insulin signaling, in mHypoA-POMC/GFP-2 neurons. This effect was mediated through the MAP kinases JNK and ERK. Further, the increase in Pomc was dependent on palmitoyl-coA synthesis, but not de novo ceramide synthesis, as inhibition of SPT enhanced palmitate-induced Pomc expression, while methylpalmitate had no effect. While palmitate concomitantly induces neuroinflammation and ER stress, these effects were independent of changes in Pomc expression. Palmitate thus has direct acute effects on Pomc, which appears to be important for negative feedback, but not directly related to neuroinflammation. The monounsaturated FFA oleate completely blocked the palmitate-mediated increase in neuroinflammation, ER stress, and Pomc mRNAs. This study provides insight into the complex central metabolic regulation by FFAs.
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Affiliation(s)
- Erika K Tse
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Denise D Belsham
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; Departments of Medicine and Obstetrics and Gynaecology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada.
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24
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Tse EK, Salehi A, Clemenzi MN, Belsham DD. Role of the saturated fatty acid palmitate in the interconnected hypothalamic control of energy homeostasis and biological rhythms. Am J Physiol Endocrinol Metab 2018; 315:E133-E140. [PMID: 29631363 DOI: 10.1152/ajpendo.00433.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The brain, specifically the hypothalamus, controls whole body energy and glucose homeostasis through neurons that synthesize specific neuropeptides, whereas hypothalamic dysfunction is linked directly to insulin resistance, obesity, and type 2 diabetes mellitus. Nutrient excess, through overconsumption of a Western or high-fat diet, exposes the hypothalamus to high levels of free fatty acids, which induces neuroinflammation, endoplasmic reticulum stress, and dysregulation of neuropeptide synthesis. Furthermore, exposure to a high-fat diet also disrupts normal circadian rhythms, and conversely, clock gene knockout models have symptoms of metabolic disorders. While whole brain/animal studies have provided phenotypic end points and important clues to the genes involved, there are still major gaps in our understanding of the intracellular pathways and neuron-specific components that ultimately control circadian rhythms and energy homeostasis. Because of its complexity and heterogeneous nature, containing a diverse mix cell types, it is difficult to dissect the critical hypothalamic components involved in these processes. Of significance, we have the capacity to study these individual components using an extensive collection of both embryonic- and adult-derived, immortalized hypothalamic neuronal cell lines from rodents. These defined neuronal cell lines have been used to examine the impact of nutrient excess, such as palmitate, on circadian rhythms and neuroendocrine signaling pathways, as well as changes in vital neuropeptides, leading to the development of neuronal inflammation; the role of proinflammatory molecules in this process; and ultimately, restoration of normal signaling, clock gene expression, and neuropeptide synthesis in disrupted states by beneficial anti-inflammatory compounds in defined hypothalamic neurons.
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Affiliation(s)
- Erika K Tse
- Department of Physiology, University of Toronto , Toronto, Ontario , Canada
| | - Ashkan Salehi
- Department of Physiology, University of Toronto , Toronto, Ontario , Canada
| | - Matthew N Clemenzi
- Department of Physiology, University of Toronto , Toronto, Ontario , Canada
| | - Denise D Belsham
- Department of Physiology, University of Toronto , Toronto, Ontario , Canada
- Department Obstetrics and Gynaecology and Medicine, University of Toronto , Toronto, Ontario , Canada
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25
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Martchenko A, Oh RH, Wheeler SE, Gurges P, Chalmers JA, Brubaker PL. Suppression of circadian secretion of glucagon-like peptide-1 by the saturated fatty acid, palmitate. Acta Physiol (Oxf) 2018; 222:e13007. [PMID: 29193800 DOI: 10.1111/apha.13007] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 11/22/2017] [Accepted: 11/23/2017] [Indexed: 12/12/2022]
Abstract
AIM Glucagon-like peptide-1 is an incretin hormone secreted by the intestinal L-cell with a circadian rhythm that parallels expression of the core clock gene, Bmal1. Although feeding rats a high-fat/high-sucrose Western diet impairs rhythmic glucagon-like peptide-1 release, the mechanisms underlying this effect remain unclear. Therefore, the aim of this study was to determine the pathway(s) by which the saturated fat, palmitate, a major component of the Western diet, impairs circadian glucagon-like peptide-1 secretion. METHODS Murine mGLUTag L-cells were synchronized, and the effects of palmitate pre-treatment on gene expression and glucagon-like peptide-1 secretion were determined, in addition to metabolite quantification, mitochondrial function analysis and enzyme inhibition and activation assays. Glucagon-like peptide-1 secretion was also analysed in ileal crypt cultures from control and Bmal1 knockout mice. RESULTS Pre-treatment with palmitate dampened Bmal1 mRNA and protein expression and glucagon-like peptide-1 secretion at 8 but not 20 hours after cell synchronization (P < .05-.001). Glucagon-like peptide-1 release was also impaired in Bmal1 knockout cultures as compared to wild-type controls (P < .001). Palmitate pre-treatment reduced expression of the Bmal1 downstream target, nicotinamide phosphoribosyltransferase, the rate-limiting enzyme in the synthesis of NAD+ . This was paralleled by dampening of total NAD+ levels, as well as impaired mitochondrial function and ATP production (P < .05-.001). Whereas direct inhibition of nicotinamide phosphoribosyltransferase also decreased glucagon-like peptide-1 release, activation of this enzyme restored glucagon-like peptide-1 secretion in the presence of palmitate. CONCLUSION Palmitate impairs L-cell clock function at the peak of Bmal1 gene expression, thereby impairing mitochondrial function and ultimately rhythmic glucagon-like peptide-1 secretion.
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Affiliation(s)
- A Martchenko
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - R H Oh
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - S E Wheeler
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - P Gurges
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - J A Chalmers
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - P L Brubaker
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Medicine, University of Toronto, Toronto, ON, Canada
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26
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Fernandes MF, Mutch DM, Leri F. The Relationship between Fatty Acids and Different Depression-Related Brain Regions, and Their Potential Role as Biomarkers of Response to Antidepressants. Nutrients 2017; 9:nu9030298. [PMID: 28304335 PMCID: PMC5372961 DOI: 10.3390/nu9030298] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 12/22/2022] Open
Abstract
Depression is a complex disorder influenced by a variety of biological and environmental factors. Due to significant heterogeneity, there are remarkable differences in how patients respond to treatment. A primary objective of psychiatric research is to identify biological markers that could be used to better predict and enhance responses to antidepressant treatments. Diet impacts various aspects of health, including depression. The fatty acid composition of the Western diet, which has a high ratio of n-6:n-3 polyunsaturated fatty acids, is associated with increased incidence of depression. The brain is rich in lipids, and dietary fatty acids act within specific brain regions to regulate processes that impact emotional behavior. This manuscript reviews existing evidence demonstrating brain region-specific fatty acid profiles, and posits that specific fatty acids may serve as predictive biomarkers of response to antidepressants. Furthermore, increasing blood levels of certain fats, such as n-3s, via dietary intervention may serve as an adjunct to improve the efficacy of antidepressants. Notably, most of the existing research regarding fats and depression-related brain regions has focused on n-3s, as compared to n-6s, monounsaturated, and saturated fats. This review article will help guide future work investigating the relationships between fatty acids, brain regions, and antidepressant efficacy.
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Affiliation(s)
- Maria Fernanda Fernandes
- Department of Psychology and Neuroscience, University of Guelph, Guelph, ON N1G 2W1, Canada.
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - David M Mutch
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Francesco Leri
- Department of Psychology and Neuroscience, University of Guelph, Guelph, ON N1G 2W1, Canada.
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Honda K, Kondo M, Hiramoto D, Saneyasu T, Kamisoyama H. Effects of continuous white light and 12h white-12h blue light-cycles on the expression of clock genes in diencephalon, liver, and skeletal muscle in chicks. Comp Biochem Physiol A Mol Integr Physiol 2017; 207:73-78. [PMID: 28238833 DOI: 10.1016/j.cbpa.2017.02.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 01/29/2017] [Accepted: 02/19/2017] [Indexed: 11/27/2022]
Abstract
The core circadian clock mechanism relies on a feedback loop comprised of clock genes, such as the brain and muscle Arnt-like 1 (Bmal1), chriptochrome 1 (Cry1), and period 3 (Per3). Exposure to the light-dark cycle synchronizes the master circadian clock in the brain, and which then synchronizes circadian clocks in peripheral tissues. Birds have long been used as a model for the investigation of circadian rhythm in human neurobiology. In the present study, we examined the effects of continuous light and the combination of white and blue light on the expression of clock genes (Bmal1, Cry1, and Per3) in the central and peripheral tissues in chicks. Seventy two day-old male chicks were weighed, allocated to three groups and maintained under three light schedules: 12h white light-12h dark-cycles group (control); 24h white light group (WW group); 12h white light-12h blue light-cycles group (WB group). The mRNA levels of clock genes in the diencephalon were significantly different between the control and WW groups. On the other hand, the alteration in the mRNA levels of clock genes was similar between the control and WB groups. Similar phenomena were observed in the liver and skeletal muscle (biceps femoris). These results suggest that 12h white-12h blue light-cycles did not disrupt the circadian rhythm of clock gene expression in chicks.
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Affiliation(s)
- Kazuhisa Honda
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
| | - Makoto Kondo
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Daichi Hiramoto
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Takaoki Saneyasu
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Hiroshi Kamisoyama
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
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28
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Ye W, Ramos EH, Wong BC, Belsham DD. Beneficial Effects of Metformin and/or Salicylate on Palmitate- or TNFα-Induced Neuroinflammatory Marker and Neuropeptide Gene Regulation in Immortalized NPY/AgRP Neurons. PLoS One 2016; 11:e0166973. [PMID: 27893782 PMCID: PMC5125651 DOI: 10.1371/journal.pone.0166973] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 11/07/2016] [Indexed: 12/30/2022] Open
Abstract
Neuropeptide Y (NPY)/Agouti-related peptide (AgRP)-expressing neurons in the hypothalamus induce feeding and decrease energy expenditure. With consumption of a diet high in fat, there is an increase in circulating saturated free fatty acids, including palmitate, leading to the development of neuroinflammation and secretion of cytokines, such as TNFα, and in turn activation of the canonical IKKβ/NFκB cascade. We describe a model of palmitate- and TNFα-induced neuroinflammation in a functionally characterized, immortalized NPY/AgRP-expressing cell model, mHypoE-46, to study whether the anti-diabetic metformin alone or in combination with the anti-inflammatory agent salicylate can ameliorate these detrimental effects. Treatment with palmitate increased mRNA expression of feeding peptides Npy and Agrp, and inflammatory cytokines Tnfa and Il-6, whereas treatment with TNFα increased mRNA expression of Npy, Nfkb, Ikba, Tnfa, and Il-6. The effects of metformin and/or sodium salicylate on these genes were assessed. Metformin increased phosphorylation of AMPK and S6K, while sodium salicylate increased phospho-AMPK and decreased phospho-S6K, but neither had any effect on phospho-ERK, -JNK or –p38 in the mHypoE-46 NPY/AgRP neurons. Furthermore, we utilized a pre-treatment and/or co-treatment paradigm to model potential clinical regimens. We determined co-treatment with metformin or sodium salicylate alone was successful in alleviating changes observed in feeding peptide mRNA regulation, whereas a preventative pre-treatment with metformin and sodium salicylate together was able to alleviate palmitate- and TNFα-induced induction of NPY and/or AgRP mRNA levels. These results highlight important differences in reactive versus preventative treatments on palmitate- and TNFα-induced neuroinflammation in NPY/AgRP neurons.
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Affiliation(s)
- Wenqing Ye
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Ernesto H. Ramos
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Brian C. Wong
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Denise D. Belsham
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Departments of Medicine and Obstetrics and Gynaecology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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29
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Loganathan N, Belsham DD. Nutrient-sensing mechanisms in hypothalamic cell models: neuropeptide regulation and neuroinflammation in male- and female-derived cell lines. Am J Physiol Regul Integr Comp Physiol 2016; 311:R217-21. [PMID: 27306829 DOI: 10.1152/ajpregu.00168.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 06/08/2016] [Indexed: 11/22/2022]
Abstract
The hypothalamus is responsible for the control of many of our physiological responses, including energy homeostasis. Of interest, there are a number of instances of sexual dimorphism documented with regard to metabolic processes. This review will discuss the necessity of utilizing both male and female models when studying the mechanisms underlying energy homeostasis, particularly those originating at the level of the hypothalamus. Because obesity often results in central neuroinflammation, we describe markers that could be used to study differences between male and female models, both the whole organism and also at the cellular level. Our laboratory has generated a wide array of immortalized hypothalamic cell models, originating from male and female rodents that we suggest could be beneficial for these types of studies. It is imperative that both sexes are considered before any recommendations for therapeutic interventions are considered.
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Affiliation(s)
| | - Denise D Belsham
- Department of Physiology, Obstetrics and Gynaecology and Medicine, University of Toronto, Toronto, Ontario, Canada
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30
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Kim SM, Neuendorff N, Chapkin RS, Earnest DJ. Role of Inflammatory Signaling in the Differential Effects of Saturated and Poly-unsaturated Fatty Acids on Peripheral Circadian Clocks. EBioMedicine 2016; 7:100-11. [PMID: 27322464 PMCID: PMC4913702 DOI: 10.1016/j.ebiom.2016.03.037] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 03/23/2016] [Accepted: 03/23/2016] [Indexed: 12/12/2022] Open
Abstract
Inflammatory signaling may play a role in high-fat diet (HFD)-related circadian clock disturbances that contribute to systemic metabolic dysregulation. Therefore, palmitate, the prevalent proinflammatory saturated fatty acid (SFA) in HFD and the anti-inflammatory, poly-unsaturated fatty acid (PUFA), docosahexaenoic acid (DHA), were analyzed for effects on circadian timekeeping and inflammatory responses in peripheral clocks. Prolonged palmitate, but not DHA, exposure increased the period of fibroblast Bmal1-dLuc rhythms. Acute palmitate treatment produced phase shifts of the Bmal1-dLuc rhythm that were larger in amplitude as compared to DHA. These phase-shifting effects were time-dependent and contemporaneous with rhythmic changes in palmitate-induced inflammatory responses. Fibroblast and differentiated adipocyte clocks exhibited cell-specific differences in the time-dependent nature of palmitate-induced shifts and inflammation. DHA and other inhibitors of inflammatory signaling (AICAR, cardamonin) repressed palmitate-induced proinflammatory responses and phase shifts of the fibroblast clock, suggesting that SFA-mediated inflammatory signaling may feed back to modulate circadian timekeeping in peripheral clocks. The saturated fatty acid (SFA) palmitate differentially modulates the circadian timekeeping mechanism in peripheral clocks; Palmitate induces time-dependent phase shifts that coincide with its rhythmic induction of inflammatory signaling; Time-dependent nature of the palmitate-induced phase shifts and inflammatory signaling is cell specific; Inhibitors of inflammatory signaling repress the proinflammatory and phase shifting effects of palmitate; Inflammatory signaling plays a role in the mechanism by which palmitate alters circadian timekeeping in peripheral clocks.
Circadian or 24-hour clocks throughout the body mediate the local temporal coordination of tissue- or cell-specific processes necessary for normal inflammatory responses and metabolic homeostasis. Dysregulation of peripheral clocks and their timekeeping function contribute to obesity-related metabolic disorders (e.g., type 2 diabetes). Our data unveil a novel mechanism by which mutual interactions between peripheral clocks and inflammatory signaling pathways dysregulate circadian timekeeping, and exacerbate proinflammatory responses to saturated fatty acids. These studies will guide the development of chronotherapeutic drug and/or dietary omega-3 fatty acid treatments for managing and preventing metabolic disorders and other inflammation-related pathologies (e.g., cardiovascular disease, stroke, arthritis).
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Affiliation(s)
- Sam-Moon Kim
- Department of Biology, Texas A&M University, College Station, TX 77843-3258, USA; Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843-3258, USA
| | - Nichole Neuendorff
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, College of Medicine, Bryan, TX 77807-3260, USA
| | - Robert S Chapkin
- Program in Integrative Nutrition & Complex Diseases, Center for Translational Environmental Health Research, Texas A&M University, College Station, TX 77843-2253, USA; Department of Nutrition & Food Science, Texas A&M University, College Station, TX 77843-2253, USA; Department of Microbial Pathogenesis and Immunology, Texas A&M University System Health Science Center, College Station, TX 77807-3260, USA.
| | - David J Earnest
- Department of Biology, Texas A&M University, College Station, TX 77843-3258, USA; Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843-3258, USA; Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, College of Medicine, Bryan, TX 77807-3260, USA.
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31
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Gil-Lozano M, Wu WK, Martchenko A, Brubaker PL. High-Fat Diet and Palmitate Alter the Rhythmic Secretion of Glucagon-Like Peptide-1 by the Rodent L-cell. Endocrinology 2016; 157:586-99. [PMID: 26646204 DOI: 10.1210/en.2015-1732] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Secretion of the incretin hormone, glucagon-like peptide-1 (GLP-1), by the intestinal L-cell is rhythmically regulated by an independent molecular clock. However, the impact of factors known to affect the activity of similar cell-autonomous clocks, such as circulating glucocorticoids and high-fat feeding, on GLP-1 secretory patterns remains to be elucidated. Herein the role of the endogenous corticosterone rhythm on the pattern of GLP-1 and insulin nutrient-induced responses was examined in corticosterone pellet-implanted rats. Moreover, the impact of nutrient excess on the time-dependent secretion of both hormones was assessed in rats fed a high-fat, high-sucrose diet. Finally, the effects of the saturated fatty acid, palmitate, on the L-cell molecular clock and GLP-1 secretion were investigated in vitro using murine GLUTag L-cells. Diurnal variations in GLP-1 and insulin nutrient-induced responses were maintained in animals lacking an endogenous corticosterone rhythm, suggesting that glucocorticoids are not the predominant entrainment factor for L-cell rhythmic activity. In addition to hyperglycemia, hyperinsulinemia, insulin resistance, and disorganization of feeding behavior, high-fat high-sucrose-fed rats showed a total abrogation of the diurnal variation in GLP-1 and insulin nutrient-induced responses, with comparable levels of both hormones at the normal peak (5:00 pm) and trough (5:00 am) of their daily pattern. Finally, palmitate incubation induced profound derangements in the rhythmic expression of circadian oscillators in GLUTag L-cells and severely impaired the secretory activity of these cells. Collectively our findings demonstrate that obesogenic diets disrupt the rhythmic activity of the L-cell, partially through a direct effect of specific nutritional components.
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Affiliation(s)
- Manuel Gil-Lozano
- Departments of Physiology (M.G.-L., W.K.W., A.M., P.L.B.) and Medicine (P.L.B.), University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - W Kelly Wu
- Departments of Physiology (M.G.-L., W.K.W., A.M., P.L.B.) and Medicine (P.L.B.), University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Alexandre Martchenko
- Departments of Physiology (M.G.-L., W.K.W., A.M., P.L.B.) and Medicine (P.L.B.), University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Patricia L Brubaker
- Departments of Physiology (M.G.-L., W.K.W., A.M., P.L.B.) and Medicine (P.L.B.), University of Toronto, Toronto, Ontario, Canada M5S 1A8
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32
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Oosterman JE, Belsham DD. Glucose Alters Per2 Rhythmicity Independent of AMPK, Whereas AMPK Inhibitor Compound C Causes Profound Repression of Clock Genes and AgRP in mHypoE-37 Hypothalamic Neurons. PLoS One 2016; 11:e0146969. [PMID: 26784927 PMCID: PMC4718556 DOI: 10.1371/journal.pone.0146969] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 12/23/2015] [Indexed: 01/11/2023] Open
Abstract
Specific neurons in the hypothalamus are regulated by peripheral hormones and nutrients to maintain proper metabolic control. It is unclear if nutrients can directly control clock gene expression. We have therefore utilized the immortalized, hypothalamic cell line mHypoE-37, which exhibits robust circadian rhythms of core clock genes. mHypoE-37 neurons were exposed to 0.5 or 5.5 mM glucose, comparable to physiological levels in the brain. Per2 and Bmal1 mRNAs were assessed every 3 hours over 36 hours. Incubation with 5.5 mM glucose significantly shortened the period and delayed the phase of Per2 mRNA levels, but had no effect on Bmal1. Glucose had no significant effect on phospho-GSK3β, whereas AMPK phosphorylation was altered. Thus, the AMPK inhibitor Compound C was utilized, and mRNA levels of Per2, Bmal1, Cryptochrome1 (Cry1), agouti-related peptide (AgRP), carnitine palmitoyltransferase 1C (Cpt1c), and O-linked N-acetylglucosamine transferase (Ogt) were measured. Remarkably, Compound C dramatically reduced transcript levels of Per2, Bmal1, Cry1, and AgRP, but not Cpt1c or Ogt. Because AMPK was not inhibited at the same time or concentrations as the clock genes, we suggest that the effect of Compound C on gene expression occurs through an AMPK-independent mechanism. The consequences of inhibition of the rhythmic expression of clock genes, and in turn downstream metabolic mediators, such as AgRP, could have detrimental effects on overall metabolic processes. Importantly, the effects of the most commonly used AMPK inhibitor Compound C should be interpreted with caution, considering its role in AMPK-independent repression of specific genes, and especially clock gene rhythm dysregulation.
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Affiliation(s)
- Johanneke E. Oosterman
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Denise D. Belsham
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Obstetrics and Gynecology, University of Toronto, Toronto, ON, Canada
- Department of Medicine, University of Toronto, Toronto, ON, Canada
- Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
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Tong X, Zhang D, Arthurs B, Li P, Durudogan L, Gupta N, Yin L. Palmitate Inhibits SIRT1-Dependent BMAL1/CLOCK Interaction and Disrupts Circadian Gene Oscillations in Hepatocytes. PLoS One 2015; 10:e0130047. [PMID: 26075729 PMCID: PMC4468094 DOI: 10.1371/journal.pone.0130047] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 05/15/2015] [Indexed: 12/12/2022] Open
Abstract
Elevated levels of serum saturated fatty acid palmitate have been shown to promote insulin resistance, increase cellular ROS production, and trigger cell apoptosis in hepatocytes during the development of obesity. However, it remains unclear whether palmitate directly impacts the circadian clock in hepatocytes, which coordinates nutritional inputs and hormonal signaling with downstream metabolic outputs. Here we presented evidence that the molecular clock is a novel target of palmitate in hepatocytes. Palmitate exposure at low dose inhibits the molecular clock activity and suppresses the cyclic expression of circadian targets including Dbp, Nr1d1 and Per2 in hepatocytes. Palmitate treatment does not seem to alter localization or reduce protein expression of BMAL1 and CLOCK, the two core components of the molecular clock in hepatocytes. Instead, palmitate destabilizes the protein-protein interaction between BMAL1-CLOCK in a dose and time-dependent manner. Furthermore, we showed that SIRT1 activators could reverse the inhibitory action of palmitate on BMAL1-CLOCK interaction and the clock gene expression, whereas inhibitors of NAD synthesis mimic the palmitate effects on the clock function. In summary, our findings demonstrated that palmitate inhibits the clock function by suppressing SIRT1 function in hepatocytes.
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Affiliation(s)
- Xin Tong
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Deqiang Zhang
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Blake Arthurs
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Pei Li
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Leigh Durudogan
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Neil Gupta
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Lei Yin
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
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Wellhauser L, Gojska NM, Belsham DD. Delineating the regulation of energy homeostasis using hypothalamic cell models. Front Neuroendocrinol 2015; 36:130-49. [PMID: 25223866 DOI: 10.1016/j.yfrne.2014.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/28/2014] [Accepted: 09/02/2014] [Indexed: 12/27/2022]
Abstract
Attesting to its intimate peripheral connections, hypothalamic neurons integrate nutritional and hormonal cues to effectively manage energy homeostasis according to the overall status of the system. Extensive progress in the identification of essential transcriptional and post-translational mechanisms regulating the controlled expression and actions of hypothalamic neuropeptides has been identified through the use of animal and cell models. This review will introduce the basic techniques of hypothalamic investigation both in vivo and in vitro and will briefly highlight the key advantages and challenges of their use. Further emphasis will be place on the use of immortalized models of hypothalamic neurons for in vitro study of feeding regulation, with a particular focus on cell lines proving themselves most fruitful in deciphering fundamental basics of NPY/AgRP, Proglucagon, and POMC neuropeptide function.
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Affiliation(s)
- Leigh Wellhauser
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Nicole M Gojska
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Denise D Belsham
- Departments of Physiology, Medicine and OB/GYN, University of Toronto, Toronto, Ontario M5G 1A8, Canada; Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario M5S 1A8, Canada.
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Oosterman JE, Kalsbeek A, la Fleur SE, Belsham DD. Impact of nutrients on circadian rhythmicity. Am J Physiol Regul Integr Comp Physiol 2014; 308:R337-50. [PMID: 25519730 DOI: 10.1152/ajpregu.00322.2014] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The suprachiasmatic nucleus (SCN) in the mammalian hypothalamus functions as an endogenous pacemaker that generates and maintains circadian rhythms throughout the body. Next to this central clock, peripheral oscillators exist in almost all mammalian tissues. Whereas the SCN is mainly entrained to the environment by light, peripheral clocks are entrained by various factors, of which feeding/fasting is the most important. Desynchronization between the central and peripheral clocks by, for instance, altered timing of food intake can lead to uncoupling of peripheral clocks from the central pacemaker and is, in humans, related to the development of metabolic disorders, including obesity and Type 2 diabetes. Diets high in fat or sugar have been shown to alter circadian clock function. This review discusses the recent findings concerning the influence of nutrients, in particular fatty acids and glucose, on behavioral and molecular circadian rhythms and will summarize critical studies describing putative mechanisms by which these nutrients are able to alter normal circadian rhythmicity, in the SCN, in non-SCN brain areas, as well as in peripheral organs. As the effects of fat and sugar on the clock could be through alterations in energy status, the role of specific nutrient sensors will be outlined, as well as the molecular studies linking these components to metabolism. Understanding the impact of specific macronutrients on the circadian clock will allow for guidance toward the composition and timing of meals optimal for physiological health, as well as putative therapeutic targets to regulate the molecular clock.
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Affiliation(s)
- Johanneke E Oosterman
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Departments of Physiology
| | - Andries Kalsbeek
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Hypothalamic Integration Mechanisms, The Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Susanne E la Fleur
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Denise D Belsham
- Departments of Physiology, Obstetrics and Gynaecology and Medicine, University of Toronto and Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada; and
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36
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Composition and Fatty-Acid Contents of the Commercial Mollusk Neptunea arthritica. Chem Nat Compd 2014. [DOI: 10.1007/s10600-014-1169-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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37
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Greco JA, Oosterman JE, Belsham DD. Differential effects of omega-3 fatty acid docosahexaenoic acid and palmitate on the circadian transcriptional profile of clock genes in immortalized hypothalamic neurons. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1049-60. [PMID: 25144192 PMCID: PMC4200380 DOI: 10.1152/ajpregu.00100.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 08/18/2014] [Indexed: 11/22/2022]
Abstract
Diets high in saturated fatty acids (SFAs) are associated with the development of circadian dysregulation, obesity, and Type 2 diabetes mellitus. Conversely, polyunsaturated fatty acids (PUFAs) have recently been identified to improve insulin sensitivity, reduce weight gain, and relieve obesity-induced inflammation. While saturated fatty acids, such as the prevalent dietary fatty acid palmitate, have been implicated in circadian disruption, there is a paucity of studies regarding the effects of PUFAs on circadian parameters. Therefore, the immortalized murine neuronal model, mHypoE-37, was utilized to examine the effects of the SFA palmitate and omega-3 PUFA docosahexaenoic acid (DHA) on circadian rhythms. The mHypoE-37 neurons express the core clock genes, Bmal1, Per2, and Rev-erbα, in a circadian manner. 25 μM of palmitate significantly increased the transcriptional expression of Bmal1, without altering the expression of inflammatory markers TLR4, IκBα, and IL-6, nor the orexigenic neuropeptide AgRP, suggesting that the observed disruption of the molecular clock is the result of a mechanism distinct from that of hypothalamic cellular inflammation. Furthermore, treatment with the PUFA DHA resulted in alterations in the circadian expression profile of Bmal1, although differentially from the effects of palmitate. In the presence of DHA, the disruptive effects of palmitate on Bmal1 were less pronounced, suggesting a protective effect of DHA. These studies are the first to identify the potential for omega-3 PUFAs to protect against palmitate-mediated dysregulation of circadian parameters and will ultimately improve the understanding of circadian control mechanisms.
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Affiliation(s)
- James A Greco
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Johanneke E Oosterman
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Denise D Belsham
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Department of Obstetrics and Gynaecology and Medicine, University of Toronto and Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada; and
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38
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Voss U, Sand E, Olde B, Ekblad E. Enteric neuropathy can be induced by high fat diet in vivo and palmitic acid exposure in vitro. PLoS One 2013; 8:e81413. [PMID: 24312551 PMCID: PMC3849255 DOI: 10.1371/journal.pone.0081413] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 10/12/2013] [Indexed: 12/21/2022] Open
Abstract
Objective Obese and/or diabetic patients have elevated levels of free fatty acids and increased susceptibility to gastrointestinal symptoms. Since the enteric nervous system is pivotal in regulating gastrointestinal functions alterations or neuropathy in the enteric neurons are suspected to occur in these conditions. Lipid induced intestinal changes, in particular on enteric neurons, were investigated in vitro and in vivo using primary cell culture and a high fat diet (HFD) mouse model. Design Mice were fed normal or HFD for 6 months. Intestines were analyzed for neuronal numbers, remodeling and lipid accumulation. Co-cultures of myenteric neurons, glia and muscle cells from rat small intestine, were treated with palmitic acid (PA) (0 – 10−3 M) and / or oleic acid (OA) (0 – 10−3 M), with or without modulators of intracellular lipid metabolism. Analyses were by immunocyto- and histochemistry. Results HFD caused substantial loss of myenteric neurons, leaving submucous neurons unaffected, and intramuscular lipid accumulation in ileum and colon. PA exposure in vitro resulted in neuronal shrinkage, chromatin condensation and a significant and concentration-dependent decrease in neuronal survival; OA exposure was neuroprotective. Carnitine palmitoyltransferase 1 inhibition, L-carnitine- or alpha lipoic acid supplementation all counteracted PA-induced neuronal loss. PA or OA alone both caused a significant and concentration-dependent loss of muscle cells in vitro. Simultaneous exposure of PA and OA promoted survival of muscle cells and increased intramuscular lipid droplet accumulation. PA exposure transformed glia from a stellate to a rounded phenotype but had no effect on their survival. Conclusions HFD and PA exposure are detrimental to myenteric neurons. Present results indicate excessive palmitoylcarnitine formation and exhausted L-carnitine stores leading to energy depletion, attenuated acetylcholine synthesis and oxidative stress to be main mechanisms behind PA-induced neuronal loss.High PA exposure is suggested to be a factor in causing diabetic neuropathy and gastrointestinal dysregulation.
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Affiliation(s)
- Ulrikke Voss
- Department of Experimental Medical Science, Lund University, Lund, Sweden
- * E-mail:
| | - Elin Sand
- Department of Clinical Science Malmö, Lund University, Malmö, Sweden
| | - Björn Olde
- Department of Clinical Science Lund, Lund University, Lund, Sweden
| | - Eva Ekblad
- Department of Experimental Medical Science, Lund University, Lund, Sweden
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Hussain G, Schmitt F, Loeffler JP, Gonzalez de Aguilar JL. Fatting the brain: a brief of recent research. Front Cell Neurosci 2013; 7:144. [PMID: 24058332 PMCID: PMC3766822 DOI: 10.3389/fncel.2013.00144] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 08/19/2013] [Indexed: 01/06/2023] Open
Abstract
Fatty acids are of paramount importance to all cells, since they provide energy, function as signaling molecules, and sustain structural integrity of cellular membranes. In the nervous system, where fatty acids are found in huge amounts, they participate in its development and maintenance throughout life. Growing evidence strongly indicates that fatty acids in their own right are also implicated in pathological conditions, including neurodegenerative diseases, mental disorders, stroke, and trauma. In this review, we focus on recent studies that demonstrate the relationships between fatty acids and function and dysfunction of the nervous system. Fatty acids stimulate gene expression and neuronal activity, boost synaptogenesis and neurogenesis, and prevent neuroinflammation and apoptosis. By doing so, they promote brain development, ameliorate cognitive functions, serve as anti-depressants and anti-convulsants, bestow protection against traumatic insults, and enhance repairing processes. On the other hand, unbalance between different fatty acid families or excess of some of them generate deleterious side effects, which limit the translatability of successful results in experimental settings into effective therapeutic strategies for humans. Despite these constraints, there exists realistic evidence to consider that nutritional therapies based on fatty acids can be of benefit to several currently incurable nervous system diseases.
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Affiliation(s)
- Ghulam Hussain
- UMR_S 1118, Université de Strasbourg Strasbourg, France ; Mécanismes Centraux et Périphériques de la Neurodégénérescence, U1118, Institut National de la Santé et de la Recherche Médicale, Faculté de Médecine, Université de Strasbourg Strasbourg, France
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