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Li R, Wang X, Lin F, Song T, Zhu X, Lei H. Mapping accumulative whole-brain activities during environmental enrichment with manganese-enhanced magnetic resonance imaging. Neuroimage 2020; 210:116588. [PMID: 32004718 DOI: 10.1016/j.neuroimage.2020.116588] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/10/2020] [Accepted: 01/24/2020] [Indexed: 11/17/2022] Open
Abstract
An enriched environment (EE) provides multi-dimensional stimuli to the brain. EE exposure for days to months induces functional and structural neuroplasticity. In this study, manganese-enhanced magnetic resonance imaging (MEMRI) was used to map the accumulative whole-brain activities associated with a 7-day EE exposure in freely-moving adult male mice, followed by c-Fos immunochemical assessments. Relative to the mice residing in a standard environment (SE), the mice subjected to EE treatment had significantly enhanced regional MEMRI signal intensities in the prefrontal cortex, somatosensory cortices, basal ganglia, amygdala, motor thalamus, lateral hypothalamus, ventral hippocampus and midbrain dopaminergic areas at the end of the 7-day exposure, likely attributing to enhanced Mn2+ uptake/transport associated with brain activities at both the regional and macroscale network levels. Some of, but not all, the brain regions in the EE-treated mice showing enhanced MEMRI signal intensity had accompanying increases in c-Fos expression. The EE-treated mice were also found to have significantly increased overall amount of food consumption, decreased body weight gain and upregulated tyrosine hydroxylase (TH) expression in the midbrain dopaminergic areas. Taken together, these results demonstrated that the 7-day EE exposure was associated with elevated cumulative activities in the nigrostriatal, mesolimbic and corticostriatal circuits underpinning reward, motivation, cognition, motor control and appetite regulation. Such accumulative activities might have served as the substrate of EE-related neuroplasticity and the beneficial effects of EE treatment on neurological/psychiatric conditions including drug addiction, Parkinson's disease and eating disorder.
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Affiliation(s)
- Ronghui Li
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, PR China; National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, PR China
| | - Xuxia Wang
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, PR China
| | - Fuchun Lin
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, PR China
| | - Tao Song
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, PR China; National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, PR China
| | - Xutao Zhu
- Shenzhen Key Lab of Neuropsychiatric Modulation and Collaborative Innovation Center for Brain Science, CAS Center for Excellence in Brain Science and Intelligence Technology, Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Hao Lei
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, PR China; National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, PR China.
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Sfera A, Osorio C, Diaz EL, Maguire G, Cummings M. The Other Obesity Epidemic-Of Drugs and Bugs. Front Endocrinol (Lausanne) 2020; 11:488. [PMID: 32849279 PMCID: PMC7411001 DOI: 10.3389/fendo.2020.00488] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022] Open
Abstract
Chronic psychiatric patients with schizophrenia and related disorders are frequently treatment-resistant and may require higher doses of psychotropic drugs to remain stable. Prolonged exposure to these agents increases the risk of weight gain and cardiometabolic disorders, leading to poorer outcomes and higher medical cost. It is well-established that obesity has reached epidemic proportions throughout the world, however it is less known that its rates are two to three times higher in mentally ill patients compared to the general population. Psychotropic drugs have emerged as a major cause of weight gain, pointing to an urgent need for novel interventions to attenuate this unintended consequence. Recently, the gut microbial community has been linked to psychotropic drugs-induced obesity as these agents were found to possess antimicrobial properties and trigger intestinal dysbiosis, depleting Bacteroidetes phylum. Since germ-free animals exposed to psychotropics have not demonstrated weight gain, altered commensal flora composition is believed to be necessary and sufficient to induce dysmetabolism. Conversely, not only do psychotropics disrupt the composition of gut microbiota but the later alter the metabolism of the former. Here we review the role of gut bacterial community in psychotropic drugs metabolism and dysbiosis. We discuss potential biomarkers reflecting the status of Bacteroidetes phylum and take a closer look at nutritional interventions, fecal microbiota transplantation, and transcranial magnetic stimulation, strategies that may lower obesity rates in chronic psychiatric patients.
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Affiliation(s)
- Adonis Sfera
- Psychiatry, Loma Linda University, Loma Linda, CA, United States
- Department of Psychiatry, Patton State Hospital, San Bernardino, CA, United States
- *Correspondence: Adonis Sfera
| | - Carolina Osorio
- Department of Psychiatry, Loma Linda University, Loma Linda, CA, United States
| | - Eddie Lee Diaz
- Department of Psychiatry, Patton State Hospital, San Bernardino, CA, United States
| | - Gerald Maguire
- Department of Psychiatry, University of California, Riverside, Riverside, CA, United States
| | - Michael Cummings
- Department of Psychiatry, Patton State Hospital, San Bernardino, CA, United States
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3
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Ulyanova A, To XV, Asad ABMA, Han W, Chuang KH. MEMRI detects neuronal activity and connectivity in hypothalamic neural circuit responding to leptin. Neuroimage 2016; 147:904-915. [PMID: 27729278 DOI: 10.1016/j.neuroimage.2016.10.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 10/03/2016] [Accepted: 10/07/2016] [Indexed: 10/20/2022] Open
Abstract
Hypothalamus plays the central role in regulating energy homeostasis. To understand the hypothalamic neurocircuit in responding to leptin, Manganese-Enhanced MRI (MEMRI) was applied. Highly elevated signal could be mapped in major nuclei of the leptin signaling pathway, including the arcuate nucleus (ARC), paraventricular nucleus (PVN), ventromedial hypothalamus (VMH) and dorsomedial hypothalamus (DMH) in fasted mice and the enhancement was reduced by leptin administration. However, whether changes in MEMRI signal reflect Ca2+ channel activity, neuronal activation or connectivity in the leptin signaling pathway are not clear. By blocking L-type Ca2+ channels, the signal enhancement in the ARC, PVN and DMH, but not VMH, was reduced. By disrupting microtubule with colchicine, signal enhancement of the secondary neural areas like DMH and PVN was delayed which is consistent with the known projection density from ARC into these regions. Finally, strong correlation between c-fos expression and MEMRI signal increase rate was observed in the ARC, VMH and DMH. Together, we provide experimental evidence that MEMRI signal could represent activity and connectivity in certain hypothalamic nuclei and hence may be used for mapping activated neuronal pathway in vivo. This understanding would facilitate the application of MEMRI for evaluation of hypothalamic dysfunction in metabolic diseases.
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Affiliation(s)
- Anna Ulyanova
- Magnetic Resonance Imaging Group, Singapore Bioimaging Consortium, Agency for Science Technology and Research (A⁎STAR), Singapore; Department of Physiology, National University of Singapore, Singapore
| | - Xuan Vinh To
- Magnetic Resonance Imaging Group, Singapore Bioimaging Consortium, Agency for Science Technology and Research (A⁎STAR), Singapore
| | - A B M A Asad
- Magnetic Resonance Imaging Group, Singapore Bioimaging Consortium, Agency for Science Technology and Research (A⁎STAR), Singapore
| | - Weiping Han
- Lab of Metabolic Medicine, Singapore Bioimaging Consortium, A⁎STAR, Singapore
| | - Kai-Hsiang Chuang
- Magnetic Resonance Imaging Group, Singapore Bioimaging Consortium, Agency for Science Technology and Research (A⁎STAR), Singapore; Department of Physiology, National University of Singapore, Singapore.
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Malheiros JM, Paiva FF, Longo BM, Hamani C, Covolan L. Manganese-Enhanced MRI: Biological Applications in Neuroscience. Front Neurol 2015. [PMID: 26217304 PMCID: PMC4498388 DOI: 10.3389/fneur.2015.00161] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Magnetic resonance imaging (MRI) is an excellent non-invasive tool to investigate biological systems. The administration of the paramagnetic divalent ion manganese (Mn2+) enhances MRI contrast in vivo. Due to similarities between Mn2+ and calcium (Ca2+), the premise of manganese-enhanced MRI (MEMRI) is that the former may enter neurons and other excitable cells through voltage-gated Ca2+ channels. As such, MEMRI has been used to trace neuronal pathways, define morphological boundaries, and study connectivity in morphological and functional imaging studies. In this article, we provide a brief overview of MEMRI and discuss recently published data to illustrate the usefulness of this method, particularly in animal models.
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Affiliation(s)
- Jackeline Moraes Malheiros
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil ; Centro de Imagens e Espectroscopia In vivo por Ressonância Magnética, Institute of Physics of São Carlos, Universidade de São Paulo , São Carlos , Brazil
| | - Fernando Fernandes Paiva
- Centro de Imagens e Espectroscopia In vivo por Ressonância Magnética, Institute of Physics of São Carlos, Universidade de São Paulo , São Carlos , Brazil
| | - Beatriz Monteiro Longo
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil
| | - Clement Hamani
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil ; Research Imaging Centre, Centre for Addiction and Mental Health , Toronto, ON , Canada ; Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute , Toronto, ON , Canada
| | - Luciene Covolan
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil
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Frost G, Sleeth ML, Sahuri-Arisoylu M, Lizarbe B, Cerdan S, Brody L, Anastasovska J, Ghourab S, Hankir M, Zhang S, Carling D, Swann JR, Gibson G, Viardot A, Morrison D, Louise Thomas E, Bell JD. The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism. Nat Commun 2014; 5:3611. [PMID: 24781306 PMCID: PMC4015327 DOI: 10.1038/ncomms4611] [Citation(s) in RCA: 1030] [Impact Index Per Article: 103.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 03/11/2014] [Indexed: 02/07/2023] Open
Abstract
Increased intake of dietary carbohydrate that is fermented in the colon by the microbiota has been reported to decrease body weight, although the mechanism remains unclear. Here we use in vivo(11)C-acetate and PET-CT scanning to show that colonic acetate crosses the blood-brain barrier and is taken up by the brain. Intraperitoneal acetate results in appetite suppression and hypothalamic neuronal activation patterning. We also show that acetate administration is associated with activation of acetyl-CoA carboxylase and changes in the expression profiles of regulatory neuropeptides that favour appetite suppression. Furthermore, we demonstrate through (13)C high-resolution magic-angle-spinning that (13)C acetate from fermentation of (13)C-labelled carbohydrate in the colon increases hypothalamic (13)C acetate above baseline levels. Hypothalamic (13)C acetate regionally increases the (13)C labelling of the glutamate-glutamine and GABA neuroglial cycles, with hypothalamic (13)C lactate reaching higher levels than the 'remaining brain'. These observations suggest that acetate has a direct role in central appetite regulation.
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Affiliation(s)
- Gary Frost
- Faculty of Medicine, Nutrition and Dietetic Research Group, Division of Diabetes, Endocrinology and Metabolism, Department of Investigative Medicine, Imperial College London, Hammersmith Campus, London W12 0NN, UK
| | - Michelle L. Sleeth
- Faculty of Medicine, Nutrition and Dietetic Research Group, Division of Diabetes, Endocrinology and Metabolism, Department of Investigative Medicine, Imperial College London, Hammersmith Campus, London W12 0NN, UK
| | - Meliz Sahuri-Arisoylu
- Metabolic and Molecular Imaging Group, MRC Clinical Science Centre, Imperial College London, London W12 0NN, UK
| | - Blanca Lizarbe
- Laboratory for Imaging and Spectroscopy by Magnetic Resonance (LISMAR), Instituto de Investigaciones Biomédicas de Madrid ‘Alberto Sols’ C.S.I.C./U.A.M., Madrid 28029, Spain
| | - Sebastian Cerdan
- Laboratory for Imaging and Spectroscopy by Magnetic Resonance (LISMAR), Instituto de Investigaciones Biomédicas de Madrid ‘Alberto Sols’ C.S.I.C./U.A.M., Madrid 28029, Spain
| | - Leigh Brody
- Metabolic and Molecular Imaging Group, MRC Clinical Science Centre, Imperial College London, London W12 0NN, UK
| | - Jelena Anastasovska
- Metabolic and Molecular Imaging Group, MRC Clinical Science Centre, Imperial College London, London W12 0NN, UK
| | - Samar Ghourab
- Metabolic and Molecular Imaging Group, MRC Clinical Science Centre, Imperial College London, London W12 0NN, UK
| | - Mohammed Hankir
- Metabolic and Molecular Imaging Group, MRC Clinical Science Centre, Imperial College London, London W12 0NN, UK
| | - Shuai Zhang
- Cellular Stress Group, MRC Clinical Science Centre, Imperial College London, London W12 0NN, UK
| | - David Carling
- Cellular Stress Group, MRC Clinical Science Centre, Imperial College London, London W12 0NN, UK
| | - Jonathan R. Swann
- Food Microbial Sciences Unit, Department of Food and Nutritional Sciences, University of Reading, Reading RG6 6AP, UK
| | - Glenn Gibson
- Food Microbial Sciences Unit, Department of Food and Nutritional Sciences, University of Reading, Reading RG6 6AP, UK
| | - Alexander Viardot
- Faculty of Medicine, Nutrition and Dietetic Research Group, Division of Diabetes, Endocrinology and Metabolism, Department of Investigative Medicine, Imperial College London, Hammersmith Campus, London W12 0NN, UK
| | - Douglas Morrison
- Stable Isotope Biochemistry Laboratory, Scottish Universities Environmental Research Centre, Rankine Avenue, Glasgow G75 0QF, UK
| | - E Louise Thomas
- Metabolic and Molecular Imaging Group, MRC Clinical Science Centre, Imperial College London, London W12 0NN, UK
| | - Jimmy D. Bell
- Metabolic and Molecular Imaging Group, MRC Clinical Science Centre, Imperial College London, London W12 0NN, UK
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Lizarbe B, Benitez A, Peláez Brioso GA, Sánchez-Montañés M, López-Larrubia P, Ballesteros P, Cerdán S. Hypothalamic metabolic compartmentation during appetite regulation as revealed by magnetic resonance imaging and spectroscopy methods. FRONTIERS IN NEUROENERGETICS 2013; 5:6. [PMID: 23781199 PMCID: PMC3680712 DOI: 10.3389/fnene.2013.00006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 05/28/2013] [Indexed: 12/14/2022]
Abstract
We review the role of neuroglial compartmentation and transcellular neurotransmitter cycling during hypothalamic appetite regulation as detected by Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS) methods. We address first the neurochemical basis of neuroendocrine regulation in the hypothalamus and the orexigenic and anorexigenic feed-back loops that control appetite. Then we examine the main MRI and MRS strategies that have been used to investigate appetite regulation. Manganese-enhanced magnetic resonance imaging (MEMRI), Blood oxygenation level-dependent contrast (BOLD), and Diffusion-weighted magnetic resonance imaging (DWI) have revealed Mn2+ accumulations, augmented oxygen consumptions, and astrocytic swelling in the hypothalamus under fasting conditions, respectively. High field 1H magnetic resonance in vivo, showed increased hypothalamic myo-inositol concentrations as compared to other cerebral structures. 1H and 13C high resolution magic angle spinning (HRMAS) revealed increased neuroglial oxidative and glycolytic metabolism, as well as increased hypothalamic glutamatergic and GABAergic neurotransmissions under orexigenic stimulation. We propose here an integrative interpretation of all these findings suggesting that the neuroendocrine regulation of appetite is supported by important ionic and metabolic transcellular fluxes which begin at the tripartite orexigenic clefts and become extended spatially in the hypothalamus through astrocytic networks becoming eventually MRI and MRS detectable.
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Affiliation(s)
- Blanca Lizarbe
- Department of Experimental Models of Human diseases, Laboratory of Imaging and Spectroscopy by Magnetic Resonance, Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC/UAM Madrid, Spain
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Imaging hypothalamic activity using diffusion weighted magnetic resonance imaging in the mouse and human brain. Neuroimage 2012; 64:448-57. [PMID: 23000787 DOI: 10.1016/j.neuroimage.2012.09.033] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 09/06/2012] [Accepted: 09/11/2012] [Indexed: 01/15/2023] Open
Abstract
Hypothalamic appetite regulation is a vital homeostatic process underlying global energy balance in animals and humans, its disturbances resulting in feeding disorders with high morbidity and mortality. The objective evaluation of appetite remains difficult, very often restricted to indirect measurements of food intake and body weight. We report here, the direct, non-invasive visualization of hypothalamic activation by fasting using diffusion weighted magnetic resonance imaging, in the mouse brain as well as in a preliminary study in the human brain. The brain of fed or fasted mice or humans were imaged at 7 or 1.5 Tesla, respectively, by diffusion weighted magnetic resonance imaging using a complete range of b values (10<b<2000s.mm(-2)). The diffusion weighted image data sets were registered and analyzed pixel by pixel using a biexponential model of diffusion, or a model-free Linear Discriminant Analysis approach. Biexponential fittings revealed statistically significant increases in the slow diffusion parameters of the model, consistent with a neurocellular swelling response in the fasted hypothalamus. Increased resolution approaches allowed the detection of increases in the diffusion parameters within the Arcuate Nucleus, Ventromedial Nucleus and Dorsomedial Nucleus. Independently, Linear Discriminant Analysis was able to classify successfully the diffusion data sets from mice and humans between fed and fasted states. Present results are consistent with increased glutamatergic neurotransmission during orexigenic firing, a process resulting in increased ionic accumulation and concomitant osmotic neurocellular swelling. This swelling response is spatially extendable through surrounding astrocytic networks until it becomes MRI detectable. Present findings open new avenues for the direct, non-invasive, evaluation of appetite disorders and other hypothalamic pathologies helping potentially in the development of the corresponding therapies.
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Differential effects of two fermentable carbohydrates on central appetite regulation and body composition. PLoS One 2012; 7:e43263. [PMID: 22952656 PMCID: PMC3430697 DOI: 10.1371/journal.pone.0043263] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 07/18/2012] [Indexed: 01/11/2023] Open
Abstract
Background Obesity is rising at an alarming rate globally. Different fermentable carbohydrates have been shown to reduce obesity. The aim of the present study was to investigate if two different fermentable carbohydrates (inulin and β-glucan) exert similar effects on body composition and central appetite regulation in high fat fed mice. Methodology/Principal Findings Thirty six C57BL/6 male mice were randomized and maintained for 8 weeks on a high fat diet containing 0% (w/w) fermentable carbohydrate, 10% (w/w) inulin or 10% (w/w) β-glucan individually. Fecal and cecal microbial changes were measured using fluorescent in situ hybridization, fecal metabolic profiling was obtained by proton nuclear magnetic resonance (1H NMR), colonic short chain fatty acids were measured by gas chromatography, body composition and hypothalamic neuronal activation were measured using magnetic resonance imaging (MRI) and manganese enhanced MRI (MEMRI), respectively, PYY (peptide YY) concentration was determined by radioimmunoassay, adipocyte cell size and number were also measured. Both inulin and β-glucan fed groups revealed significantly lower cumulative body weight gain compared with high fat controls. Energy intake was significantly lower in β-glucan than inulin fed mice, with the latter having the greatest effect on total adipose tissue content. Both groups also showed an increase in the numbers of Bifidobacterium and Lactobacillus-Enterococcus in cecal contents as well as feces. β- glucan appeared to have marked effects on suppressing MEMRI associated neuronal signals in the arcuate nucleus, ventromedial hypothalamus, paraventricular nucleus, periventricular nucleus and the nucleus of the tractus solitarius, suggesting a satiated state. Conclusions/Significance Although both fermentable carbohydrates are protective against increased body weight gain, the lower body fat content induced by inulin may be metabolically advantageous. β-glucan appears to suppress neuronal activity in the hypothalamic appetite centers. Differential effects of fermentable carbohydrates open new possibilities for nutritionally targeting appetite regulation and body composition.
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Anastasovska J, Arora T, Sanchez Canon GJ, Parkinson JRC, Touhy K, Gibson GR, Nadkarni NA, So PW, Goldstone AP, Thomas EL, Hankir MK, Van Loo J, Modi N, Bell JD, Frost G. Fermentable carbohydrate alters hypothalamic neuronal activity and protects against the obesogenic environment. Obesity (Silver Spring) 2012; 20:1016-23. [PMID: 22322344 DOI: 10.1038/oby.2012.6] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Obesity has become a major global health problem. Recently, attention has focused on the benefits of fermentable carbohydrates on modulating metabolism. Here, we take a system approach to investigate the physiological effects of supplementation with oligofructose-enriched inulin (In). We hypothesize that supplementation with this fermentable carbohydrate will not only lead to changes in body weight and composition, but also to modulation in neuronal activation in the hypothalamus. Male C57BL/6 mice were maintained on a normal chow diet (control) or a high fat (HF) diet supplemented with either oligofructose-enriched In or corn starch (Cs) for 9 weeks. Compared to HF+Cs diet, In supplementation led to significant reduction in average daily weight gain (mean ± s.e.m.: 0.19 ± 0.01 g vs. 0.26 ± 0.02 g, P < 0.01), total body adiposity (24.9 ± 1.2% vs. 30.7 ± 1.4%, P < 0.01), and lowered liver fat content (11.7 ± 1.7% vs. 23.8 ± 3.4%, P < 0.01). Significant changes were also observed in fecal bacterial distribution, with increases in both Bifidobacteria and Lactobacillius and a significant increase in short chain fatty acids (SCFA). Using manganese-enhanced MRI (MEMRI), we observed a significant increase in neuronal activation within the arcuate nucleus (ARC) of animals that received In supplementation compared to those fed HF+Cs diet. In conclusion, we have demonstrated for the first time, in the same animal, a wide range of beneficial metabolic effects following supplementation of a HF diet with oligofructose-enriched In, as well as significant changes in hypothalamic neuronal activity.
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Affiliation(s)
- Jelena Anastasovska
- Metabolic and Molecular Imaging Group, MRC Clinical Sciences Centre, Imperial College London, London, UK
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Is there a path beyond BOLD? Molecular imaging of brain function. Neuroimage 2012; 62:1208-15. [PMID: 22406355 DOI: 10.1016/j.neuroimage.2012.02.076] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 02/18/2012] [Accepted: 02/27/2012] [Indexed: 12/20/2022] Open
Abstract
The dependence of BOLD on neuro-vascular coupling leaves it many biological steps removed from direct monitoring of neural function. MRI based approaches have been developed aimed at reporting more directly on brain function. These include: manganese enhanced MRI as a surrogate for calcium ion influx; agents responsive to calcium concentrations; approaches to measure membrane potential; agents to measure neurotransmitters; and strategies to measure gene expression. This work has led to clever design of molecular imaging tools and many contributions to studies of brain function in animal models. However, a robust approach that has potential to get MRI closer to neurons in the human brain has not yet emerged.
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11
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Hankir MK, Parkinson JR, Bloom SR, Bell JD. The effects of glutamate receptor agonists and antagonists on mouse hypothalamic and hippocampal neuronal activity shown through manganese enhanced MRI. Neuroimage 2011; 59:968-78. [PMID: 21925279 DOI: 10.1016/j.neuroimage.2011.08.063] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 08/05/2011] [Accepted: 08/21/2011] [Indexed: 11/17/2022] Open
Abstract
Manganese enhanced MRI (MEMRI) is an imaging paradigm that can be used to assess neuronal activity in vivo. Here we investigate, through the use of MEMRI, the influence of receptor dynamics on neuronal activity in the hypothalamus and hippocampus focusing on the glutamate receptor signalling system. We demonstrate that intraperitoneal (i.p.) administration of monosodium glutamate (MSG) and the ionotropic glutamate receptor (iGluR) agonists NMDA and AMPA resulted in significantly increased signal intensity (SI) in the arcuate nucleus (ARC), the suprachiasmatic nucleus (SCN) and the CA3 region of the hippocampus of mice consistent with increased neuronal activity. Administration of the NMDA receptor antagonist MK-801 resulted in significantly decreased SI in the paraventricular nucleus (PVN) consistent with decreased neuronal activity. Co-administration of MSG and the AMPA receptor antagonist NBQX attenuated the increase in SI observed in the ARC from MSG alone, suggesting MEMRI may be applicable to the study of receptor dynamics in vivo. We also observed that administration of the various iGluR agonists and antagonists modulated SI in the lateral ventricle and that high dose MSG (300 mg) caused a hitherto unseen enhancement in SI in the entire cortical/subarachnoid region. In conclusion, MEMRI reveals changes in neuronal activity in response to iGluR agonists and antagonists in the CNS in vivo as well as revealing multifaceted effects beyond those attributable to neuronal activity alone.
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Affiliation(s)
- Mohammed K Hankir
- Metabolic and Molecular Imaging Group, MRC Clinical Sciences Centre, Imperial College London, 3rd Floor Cyclotron Building, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.
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Hankir MK, Parkinson JRC, Minnion JS, Addison ML, Bloom SR, Bell JD. Peptide YY 3-36 and pancreatic polypeptide differentially regulate hypothalamic neuronal activity in mice in vivo as measured by manganese-enhanced magnetic resonance imaging. J Neuroendocrinol 2011; 23:371-80. [PMID: 21251093 DOI: 10.1111/j.1365-2826.2011.02111.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Peptide YY (PYY) and pancreatic polypeptide (PP) are two appetite suppressing hormones, released post-prandially from the ileum and pancreas, respectively. PYY(3-36) , the major circulating form of the peptide, is considered to reduce food intake in humans and rodents via high affinity binding to the auto-inhibitory neuropeptide Y receptor Y2R, whereas PP is considered to act through the Y4R. Current evidence indicates the anorexigenic effects of both peptides occur via signalling in the brainstem and arcuate nucleus (ARC) of the hypothalamus. Manganese-enhanced magnetic resonance imaging (MEMRI) has previously been used to track hypothalamic neuronal activity in vivo in response to both nutritional interventions and gut hormone treatment. In the present study, we used MEMRI to demonstrate that s.c. administration of PP results in a significant reduction in signal intensity (SI) in the ARC, ventromedial hypothalamus and paraventricular nucleus of fasted mice. Subcutaneous delivery of PYY(3-36) resulted in a nonsignificant trend towards decreased SI in the hypothalamus of fasted mice. We found no SI change in the area postrema of the brainstem after s.c. injection of either peptide. These differences in hypothalamic SI profile between PP and PYY(3-36) occurred despite both peptides producing a comparable reduction in food intake. These results suggest that separate central pathways control the anorexigenic response for PP and PYY(3-36) , possibly via a differential effect of Y4 receptor versus Y2 receptor signalling. In addition, we performed a series of MEMRI scans at 0-2, 2-4 and 4-6 h post-injection of PYY(3-36) and a potent analogue of the peptide; PYY(3-36) (LT). We recorded a significant reduction in the ARC SI 2-4 h after PYY(3-36) (LT) injection compared to both saline and PYY(3-36) in fasted mice. The physiological differences between PYY(3-36) and its analogue were also observed in the long-term effects on food intake, with PYY(3-36) (LT) producing a more sustained anorexigenic effect. These data suggest that MEMRI can be used to investigate the long-term effects of gut peptide delivery on activity within the hypothalamus and brainstem.
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Affiliation(s)
- M K Hankir
- Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
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13
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Abstract
The use of manganese ions (Mn(2+)) as an MRI contrast agent was introduced over 20 years ago in studies of Mn(2+) toxicity in anesthetized rats (1). Manganese-enhanced MRI (MEMRI) evolved in the late nineties when Koretsky and associates pioneered the use of MEMRI for brain activity measurements (2) as well as neuronal tract tracing (3). Currently, MEMRI has three primary applications in biological systems: (1) contrast enhancement for anatomical detail, (2) activity-dependent assessment and (3) tracing of neuronal connections or tract tracing. MEMRI relies upon the following three main properties of Mn(2+): (1) it is a paramagnetic ion that shortens the spin lattice relaxation time constant (T(1)) of tissues, where it accumulates and hence functions as an excellent T(1) contrast agent; (2) it is a calcium (Ca(2+)) analog that can enter excitable cells, such as neurons and cardiac cells via voltage-gated Ca(2+) channels; and (3) once in the cells Mn(2+) can be transported along axons by microtubule-dependent axonal transport and can also cross synapses trans-synaptically to neighboring neurons. This chapter will emphasize the methodological approaches towards the use of MEMRI in biological systems.
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Affiliation(s)
- Cynthia A Massaad
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA.
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14
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Gibson CD, Carnell S, Ochner CN, Geliebter A. Neuroimaging, gut peptides and obesity: novel studies of the neurobiology of appetite. J Neuroendocrinol 2010; 22:833-45. [PMID: 20553371 PMCID: PMC3121301 DOI: 10.1111/j.1365-2826.2010.02025.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Two major biological players in the regulation of body weight are the gut and the brain. Peptides released from the gut convey information about energy needs to areas of the brain involved in homeostatic control of food intake. There is emerging evidence that human food intake is also under the control of cortical and subcortical areas related to reward and cognition. The extent to which gut hormones influence these brain areas is not fully understood. Novel methods combining the study of neural activity and hormonal signalling promise to advance our understanding of gut-brain interactions. Here, we review a growing number of animal and human studies using neuroimaging methods (functional magnetic resonance imaging, positron emission tomography) to measure brain activation in relation to nutrient loads and infusion of gut peptides. Implications for current and future pharmacological treatments for obesity are discussed.
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Affiliation(s)
- C D Gibson
- New York Obesity Research Center, St Luke's-Roosevelt Hospital Center, Columbia University College of Physicians and Surgeons, New York, NY, USA.
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15
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Delzenne N, Blundell J, Brouns F, Cunningham K, De Graaf K, Erkner A, Lluch A, Mars M, Peters HPF, Westerterp-Plantenga M. Gastrointestinal targets of appetite regulation in humans. Obes Rev 2010; 11:234-50. [PMID: 20433660 DOI: 10.1111/j.1467-789x.2009.00707.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The aim of this paper is to describe and discuss relevant aspects of the assessment of physiological functions - and related biomarkers - implicated in the regulation of appetite in humans. A short introduction provides the background and the present state of biomarker research as related to satiety and appetite. The main focus of the paper is on the gastrointestinal tract and its functions and biomarkers related to appetite for which sufficient data are available in human studies. The first section describes how gastric emptying, stomach distension and gut motility influence appetite; the second part describes how selected gastrointestinal peptides are involved in the control of satiety and appetite (ghrelin, cholecystokinin, glucagon-like peptide, peptide tyrosin-tyrosin) and can be used as potential biomarkers. For both sections, methodological aspects (adequacy, accuracy and limitation of the methods) are described. The last section focuses on new developments in techniques and methods for the assessment of physiological targets involved in appetite regulation (including brain imaging, interesting new experimental approaches, targets and markers). The conclusion estimates the relevance of selected biomarkers as representative markers of appetite regulation, in view of the current state of the art.
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Affiliation(s)
- N Delzenne
- Louvain Drug Research Institute, Unit PMNT 7369, Université Catholique de Louvain, Brussels, Belgium
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16
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Goldstone AP, Prechtl de Hernandez CG, Beaver JD, Muhammed K, Croese C, Bell G, Durighel G, Hughes E, Waldman AD, Frost G, Bell JD. Fasting biases brain reward systems towards high-calorie foods. Eur J Neurosci 2009; 30:1625-35. [DOI: 10.1111/j.1460-9568.2009.06949.x] [Citation(s) in RCA: 251] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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