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Mishra D, Richard JE, Maric I, Shevchouk OT, Börchers S, Eerola K, Krieger JP, Skibicka KP. Lateral parabrachial nucleus astrocytes control food intake. Front Endocrinol (Lausanne) 2024; 15:1389589. [PMID: 38887265 PMCID: PMC11180714 DOI: 10.3389/fendo.2024.1389589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 05/03/2024] [Indexed: 06/20/2024] Open
Abstract
Food intake behavior is under the tight control of the central nervous system. Most studies to date focus on the contribution of neurons to this behavior. However, although previously overlooked, astrocytes have recently been implicated to play a key role in feeding control. Most of the recent literature has focused on astrocytic contribution in the hypothalamus or the dorsal vagal complex. The contribution of astrocytes located in the lateral parabrachial nucleus (lPBN) to feeding behavior control remains poorly understood. Thus, here, we first investigated whether activation of lPBN astrocytes affects feeding behavior in male and female rats using chemogenetic activation. Astrocytic activation in the lPBN led to profound anorexia in both sexes, under both ad-libitum feeding schedule and after a fasting challenge. Astrocytes have a key contribution to glutamate homeostasis and can themselves release glutamate. Moreover, lPBN glutamate signaling is a key contributor to potent anorexia, which can be induced by lPBN activation. Thus, here, we determined whether glutamate signaling is necessary for lPBN astrocyte activation-induced anorexia, and found that pharmacological N-methyl D-aspartate (NMDA) receptor blockade attenuated the food intake reduction resulting from lPBN astrocyte activation. Since astrocytes have been shown to contribute to feeding control by modulating the feeding effect of peripheral feeding signals, we further investigated whether lPBN astrocyte activation is capable of modulating the anorexic effect of the gut/brain hormone, glucagon like peptide -1, as well as the orexigenic effect of the stomach hormone - ghrelin, and found that the feeding effect of both signals is modulated by lPBN astrocytic activation. Lastly, we found that lPBN astrocyte activation-induced anorexia is affected by a diet-induced obesity challenge, in a sex-divergent manner. Collectively, current findings uncover a novel role for lPBN astrocytes in feeding behavior control.
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Affiliation(s)
- Devesh Mishra
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Jennifer E. Richard
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada
| | - Ivana Maric
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA, United States
| | - Olesya T. Shevchouk
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Stina Börchers
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA, United States
| | - Kim Eerola
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Jean-Philippe Krieger
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
- Institute of Veterinary Pharmacology and Toxicology, University of Zurich - VetSuisse, Zurich, Switzerland
| | - Karolina P. Skibicka
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA, United States
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States
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2
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Meadows SM, Palaguachi F, Jang MW, Licht-Murava A, Barnett D, Zimmer TS, Zhou C, McDonough SR, Orr AL, Orr AG. Hippocampal astrocytes induce sex-dimorphic effects on memory. Cell Rep 2024; 43:114278. [PMID: 38795347 DOI: 10.1016/j.celrep.2024.114278] [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: 10/27/2023] [Revised: 03/19/2024] [Accepted: 05/09/2024] [Indexed: 05/27/2024] Open
Abstract
Astrocytic receptors influence cognitive function and can promote behavioral deficits in disease. These effects may vary based on variables such as biological sex, but it is not known if the effects of astrocytic receptors are dependent on sex. We leveraged in vivo gene editing and chemogenetics to examine the roles of astrocytic receptors in spatial memory and other processes. We show that reductions in metabotropic glutamate receptor 3 (mGluR3), the main astrocytic glutamate receptor in adults, impair memory in females but enhance memory in males. Similarly, increases in astrocytic mGluR3 levels have sex-dependent effects and enhance memory in females. mGluR3 manipulations also alter spatial search strategies during recall in a sex-specific manner. In addition, acute chemogenetic stimulation of Gi/o-coupled or Gs-coupled receptors in hippocampal astrocytes induces bidirectional and sex-dimorphic effects on memory. Thus, astrocytes are sex-dependent modulators of cognitive function and may promote sex differences in aging and disease.
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Affiliation(s)
- Samantha M Meadows
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Neuroscience Graduate Program, Weill Cornell Medicine, New York, NY 10021, USA
| | - Fernando Palaguachi
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Minwoo Wendy Jang
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Avital Licht-Murava
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Daniel Barnett
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Neuroscience Graduate Program, Weill Cornell Medicine, New York, NY 10021, USA
| | - Till S Zimmer
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Constance Zhou
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10021, USA
| | - Samantha R McDonough
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Neuroscience Graduate Program, Weill Cornell Medicine, New York, NY 10021, USA
| | - Adam L Orr
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Neuroscience Graduate Program, Weill Cornell Medicine, New York, NY 10021, USA
| | - Anna G Orr
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Neuroscience Graduate Program, Weill Cornell Medicine, New York, NY 10021, USA; Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10021, USA.
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3
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Firth W, Robb JL, Stewart D, Pye KR, Bamford R, Oguro-Ando A, Beall C, Ellacott KLJ. Regulation of astrocyte metabolism by mitochondrial translocator protein 18 kDa. J Neurochem 2024. [PMID: 38482552 DOI: 10.1111/jnc.16089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 02/15/2024] [Accepted: 02/17/2024] [Indexed: 03/26/2024]
Abstract
The mitochondrial translocator protein 18 kDa (TSPO) has been linked to functions from steroidogenesis to regulation of cellular metabolism and is an attractive therapeutic target for chronic CNS inflammation. Studies in Leydig cells and microglia indicate that TSPO function may vary between cells depending on their specialized roles. Astrocytes are critical for providing trophic and metabolic support in the brain. Recent work has highlighted that TSPO expression increases in astrocytes under inflamed conditions and may drive astrocyte reactivity. Relatively little is known about the role TSPO plays in regulating astrocyte metabolism and whether this protein is involved in immunometabolic processes in these cells. Using TSPO-deficient (TSPO-/- ) mouse primary astrocytes in vitro (MPAs) and a human astrocytoma cell line (U373 cells), we performed extracellular metabolic flux analyses. We found that TSPO deficiency reduced basal cellular respiration and attenuated the bioenergetic response to glucopenia. Fatty acid oxidation was increased, and lactate production was reduced in TSPO-/- MPAs and U373 cells. Co-immunoprecipitation studies revealed that TSPO forms a complex with carnitine palmitoyltransferase 1a in U373 and MPAs, presenting a mechanism wherein TSPO may regulate FAO in these cells. Compared to TSPO+/+ cells, in TSPO-/- MPAs we observed attenuated tumor necrosis factor release following 3 h lipopolysaccharide (LPS) stimulation, which was enhanced at 24 h post-LPS stimulation. Together these data suggest that while TSPO acts as a regulator of metabolic flexibility, TSPO deficiency does not appear to modulate the metabolic response of MPAs to inflammation, at least in response to the model used in this study.
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Affiliation(s)
- Wyn Firth
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Josephine L Robb
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Daisy Stewart
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Katherine R Pye
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Rosemary Bamford
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Asami Oguro-Ando
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Craig Beall
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Kate L J Ellacott
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
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Lai TT, Tsai YH, Liou CW, Fan CH, Hou YT, Yao TH, Chuang HL, Wu WL. The gut microbiota modulate locomotion via vagus-dependent glucagon-like peptide-1 signaling. NPJ Biofilms Microbiomes 2024; 10:2. [PMID: 38228675 DOI: 10.1038/s41522-024-00477-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 01/04/2024] [Indexed: 01/18/2024] Open
Abstract
Locomotor activity is an innate behavior that can be triggered by gut-motivated conditions, such as appetite and metabolic condition. Various nutrient-sensing receptors distributed in the vagal terminal in the gut are crucial for signal transduction from the gut to the brain. The levels of gut hormones are closely associated with the colonization status of the gut microbiota, suggesting a complicated interaction among gut bacteria, gut hormones, and the brain. However, the detailed mechanism underlying gut microbiota-mediated endocrine signaling in the modulation of locomotion is still unclear. Herein, we show that broad-spectrum antibiotic cocktail (ABX)-treated mice displayed hypolocomotion and elevated levels of the gut hormone glucagon-like peptide-1 (GLP-1). Blockade of the GLP-1 receptor and subdiaphragmatic vagal transmission rescued the deficient locomotor phenotype in ABX-treated mice. Activation of the GLP-1 receptor and vagal projecting brain regions led to hypolocomotion. Finally, selective antibiotic treatment dramatically increased serum GLP-1 levels and decreased locomotion. Colonizing Lactobacillus reuteri and Bacteroides thetaiotaomicron in microbiota-deficient mice suppressed GLP-1 levels and restored the hypolocomotor phenotype. Our findings identify a mechanism by which specific gut microbes mediate host motor behavior via the enteroendocrine and vagal-dependent neural pathways.
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Affiliation(s)
- Tzu-Ting Lai
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan
- Department of Physiology, College of Medicine, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan
| | - Yu-Hsuan Tsai
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan
- Department of Physiology, College of Medicine, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan
| | - Chia-Wei Liou
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan
- Department of Physiology, College of Medicine, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan
| | - Ching-Hsiang Fan
- Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan
| | - Yu-Tian Hou
- Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan
| | - Tzu-Hsuan Yao
- Department of Physiology, College of Medicine, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan
| | - Hsiao-Li Chuang
- National Laboratory Animal Center, National Applied Research Laboratories, Taipei, 115202, Taiwan
| | - Wei-Li Wu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan.
- Department of Physiology, College of Medicine, National Cheng Kung University, 1 University Rd., Tainan, 70101, Taiwan.
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5
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Firth W, Robb JL, Stewart D, Pye KR, Bamford R, Oguro-Ando A, Beall C, Ellacott KLJ. Regulation of astrocyte metabolism by mitochondrial translocator protein 18kDa. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.29.560159. [PMID: 37873215 PMCID: PMC10592862 DOI: 10.1101/2023.09.29.560159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
The mitochondrial translocator protein 18kDa (TSPO) has been linked to a variety of functions from steroidogenesis to regulation of cellular metabolism and is an attractive therapeutic target for chronic CNS inflammation. Studies in the periphery using Leydig cells and hepatocytes, as well as work in microglia, indicate that the function of TSPO may vary between cells depending on their specialised roles. Astrocytes are critical for providing trophic and metabolic support in the brain as part of their role in maintaining brain homeostasis. Recent work has highlighted that TSPO expression increases in astrocytes under inflamed conditions and may drive astrocyte reactivity. However, relatively little is known about the role TSPO plays in regulating astrocyte metabolism and whether this protein is involved in immunometabolic processes in these cells. Using TSPO-deficient (TSPO-/-) mouse primary astrocytes in vitro (MPAs) and a human astrocytoma cell line (U373 cells), we performed metabolic flux analyses. We found that loss of TSPO reduced basal astrocyte respiration and increased the bioenergetic response to glucose reintroduction following glucopenia, while increasing fatty acid oxidation (FAO). Lactate production was significantly reduced in TSPO-/- astrocytes. Co-immunoprecipitation studies in U373 cells revealed that TSPO forms a complex with carnitine palmitoyltransferase 1a, which presents a mechanism wherein TSPO may regulate FAO in astrocytes. Compared to TSPO+/+ cells, inflammation induced by 3h lipopolysaccharide (LPS) stimulation of TSPO-/- MPAs revealed attenuated tumour necrosis factor release, which was enhanced in TSPO-/- MPAs at 24h LPS stimulation. Together these data suggest that while TSPO acts as a regulator of metabolic flexibility in astrocytes, loss of TSPO does not appear to modulate the metabolic response of astrocytes to inflammation, at least in response to the stimulus/time course used in this study.
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Affiliation(s)
- Wyn Firth
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Josephine L Robb
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Daisy Stewart
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Katherine R Pye
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Rosemary Bamford
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Asami Oguro-Ando
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Craig Beall
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Kate LJ Ellacott
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
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6
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Fozzato A, New LE, Griffiths JC, Patel B, Deuchars SA, Filippi BM. Manipulating mitochondrial dynamics in the NTS prevents diet-induced deficits in brown fat morphology and glucose uptake. Life Sci 2023; 328:121922. [PMID: 37423379 DOI: 10.1016/j.lfs.2023.121922] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 07/06/2023] [Accepted: 07/06/2023] [Indexed: 07/11/2023]
Abstract
AIMS Brown adipose tissue (BAT) can produce heat by metabolizing glucose and fatty acids. Activation of BAT is controlled by the central nervous system (CNS) through sympathetic innervation. Dysregulation of signalling molecules in selective CNS areas such as the nucleus of tractus solitarius (NTS) are linked with altered BAT activity, obesity and diabetes. High-fat diet (HFD)-feeding increases mitochondrial fragmentation in the NTS, triggering insulin resistance, hyperphagia and weight gain. Here we sought to determine whether changes in mitochondrial dynamics in the NTS can affect BAT glucose uptake. MAIN METHODS Rats received DVC stereotactic surgery for local brain administration of viruses that express mutated Drp1 genes. BAT glucose uptake was measured with PET/CT scans. Biochemical assays and immunohistochemistry determined altered levels of key signalling molecules and neural innervation of BAT. KEY FINDINGS We show that short-term HFD-feeding decreases BAT glucose uptake. However, inhibiting mitochondrial fragmentation in NTS-astrocytes of HFD-fed rats partially restores BAT glucose uptake accompanied by lower blood glucose and insulin levels. Tyrosine Hydroxylase (TH) revealed that rats with inhibited mitochondrial fragmentation in NTS astrocytes had higher levels of catecholaminergic innervation in BAT compared to HFD-fed rats, and did not exhibit HFD-dependent infiltration of enlarged white fat droplets in the BAT. In regular chow-fed rats, increasing mitochondrial fragmentation in the NTS-astrocytes reduced BAT glucose uptake, TH immune-positive boutons and β3-adrenergic receptor levels. SIGNIFICANCE Our data suggest that targeting mitochondrial dynamics in the NTS-astrocytes could be a beneficial strategy to increase glucose utilization and protect from developing obesity and diabetes.
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Affiliation(s)
- Arianna Fozzato
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Lauryn E New
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Joanne C Griffiths
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Bianca Patel
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Susan A Deuchars
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Beatrice M Filippi
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
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7
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MacDonald AJ, Pye KR, Beall C, Ellacott KLJ. Impact of chemogenetic activation of dorsal vagal complex astrocytes in mice on adaptive glucoregulatory responses. J Neuroendocrinol 2023; 35:e13315. [PMID: 37370201 DOI: 10.1111/jne.13315] [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: 11/13/2022] [Revised: 05/13/2023] [Accepted: 05/31/2023] [Indexed: 06/29/2023]
Abstract
The dorsal vagal complex (DVC) regulates diverse aspects of physiology including food intake and blood glucose homeostasis. Astrocytes play an active role in regulating DVC function and, by extension, physiological parameters. DVC astrocytes in ex vivo slices respond to low tissue glucose. The response of neurons to low glucose is conditional on intact astrocyte signalling in slice preparations, suggesting astrocytes are primary sensors of glucose deprivation (glucoprivation). Based on these published findings we hypothesised that in vivo DVC astrocyte manipulation with chemogenetics would be sufficient to alter physiological responses that control blood glucose. We found that 2-h after systemic 2-DG-induced glucoprivation there were no observable changes in morphology of glial fibrillary acidic protein (GFAP)-immunoreactive DVC cells, specifically those in the nucleus of the solitary tract (NTS). Chemogenetic activation of DVC astrocytes was sufficient to suppress nocturnal food intake by reducing both meal size and meal number and this manipulation also suppressed 2-DG-induced glucoprivic food intake. Chemogenetic activation of DVC astrocytes did not increase basal blood glucose nor protect against insulin-induced hypoglycaemia. In male mice, chemogenetic DVC astrocyte activation did not alter glucose tolerance. In female mice, the initial glucose excursion was reduced in a glucose tolerance test, suggesting enhanced glucose absorption. Based on our data and published work, we propose that DVC astrocytes may play an indispensable homeostatic role, that is, are necessary to maintain the function of glucoregulatory neuronal circuitry, but alone their bulk activation is not sufficient to result in adaptive glucoregulatory responses. It is possible that there are state-dependent effects and/or DVC astrocyte subsets that have this specialised role, but this was unresolvable using the experimental approaches employed here.
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Affiliation(s)
- Alastair J MacDonald
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Katherine R Pye
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Craig Beall
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Kate L J Ellacott
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, UK
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8
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Ahern J, Chrobok Ł, Champneys AR, Piggins HD. A new phase model of the spatiotemporal relationships between three circadian oscillators in the brainstem. Sci Rep 2023; 13:5480. [PMID: 37016055 PMCID: PMC10073201 DOI: 10.1038/s41598-023-32315-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 03/25/2023] [Indexed: 04/06/2023] Open
Abstract
Analysis of ex vivo Per2 bioluminescent rhythm previously recorded in the mouse dorsal vagal complex reveals a characteristic phase relationship between three distinct circadian oscillators. These signals represent core clock gene expression in the area postrema (AP), the nucleus of the solitary tract (NTS) and the ependymal cells surrounding the 4th ventricle (4Vep). Initially, the data suggests a consistent phasing in which the AP peaks first, followed shortly by the NTS, with the 4Vep peaking 8-9 h later. Wavelet analysis reveals that this pattern is not consistently maintained throughout a recording, however, the phase dynamics strongly imply that oscillator interactions are present. A simple phase model of the three oscillators is developed and it suggests that realistic phase dynamics occur between three model oscillators with coupling close to a synchronisation transition. The coupling topology suggests that the AP bidirectionally communicates phase information to the NTS and the 4Vep to synchronise the three structures. A comparison of the model with previous experimental manipulations demonstrates its feasibility to explain DVC circadian phasing. Finally, we show that simulating steadily decaying coupling improves the model's ability to capture experimental phase dynamics.
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Affiliation(s)
- Jake Ahern
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
- Engineering Mathematics, University of Bristol, Bristol, BS8 1TW, UK
| | - Łukasz Chrobok
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
| | - Alan R Champneys
- Engineering Mathematics, University of Bristol, Bristol, BS8 1TW, UK
| | - Hugh D Piggins
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK.
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9
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Clyburn C, Carson KE, Smith CR, Travagli RA, Browning KN. Brainstem astrocytes control homeostatic regulation of caloric intake. J Physiol 2023; 601:801-829. [PMID: 36696965 PMCID: PMC10026361 DOI: 10.1113/jp283566] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 12/08/2022] [Indexed: 01/27/2023] Open
Abstract
Prolonged high-fat diet (HFD) exposure is associated with hyperphagia, excess caloric intake and weight gain. After initial exposure to a HFD, a brief (24-48 h) period of hyperphagia is followed by the regulation of caloric intake and restoration of energy balance within an acute (3-5 day) period. Previous studies have demonstrated this occurs via a vagally mediated signalling cascade that increases glutamatergic transmission via activation of NMDA receptors located on gastric-projecting neurons of the dorsal motor nucleus of the vagus (DMV). The present study used electrophysiological recordings from thin brainstem slice preparations, in vivo recordings of gastric motility and tone, measurement of gastric emptying rates, and food intake studies to investigate the hypothesis that activation of brainstem astrocytes in response to acute HFD exposure is responsible for the increased glutamatergic drive to DMV neurons and the restoration of caloric balance. Pharmacological and chemogenetic inhibition of brainstem astrocytes reduced glutamatergic signalling and DMV excitability, dysregulated gastric tone and motility, attenuated the homeostatic delay in gastric emptying, and prevented the decrease in food intake that is observed during the period of energy regulation following initial exposure to HFD. Understanding the mechanisms involved in caloric regulation may provide critical insights into energy balance as well as into the hyperphagia that develops as these mechanisms are overcome. KEY POINTS: Initial exposure to a high fat diet is associated with a brief period of hyperphagia before caloric intake and energy balance is restored. This period of homeostatic regulation is associated with a vagally mediated signalling cascade that increases glutamatergic transmission to dorsal motor nucleus of the vagus (DMV) neurons via activation of synaptic NMDA receptors. The present study demonstrates that pharmacological and chemogenetic inhibition of brainstem astrocytes reduced glutamatergic signalling and DMV neuronal excitability, dysregulated gastric motility and tone and emptying, and prevented the regulation of food intake following high-fat diet exposure. Astrocyte regulation of glutamatergic transmission to DMV neurons appears to involve release of the gliotransmitters glutamate and ATP. Understanding the mechanisms involved in caloric regulation may provide critical insights into energy balance as well as into the hyperphagia that develops as these mechanisms are overcome.
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Affiliation(s)
- Courtney Clyburn
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA
- Current position: Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, 97056
| | - Kaitlin E. Carson
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA
| | - Caleb R. Smith
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA
| | - R. Alberto Travagli
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA
- Current position: Neurobiology Research, Newport, NC 28570
| | - Kirsteen N. Browning
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA
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10
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Yang L, Lu J, Guo J, Chen J, Xiong F, Wang X, Chen L, Yu C. Ventrolateral Periaqueductal Gray Astrocytes Regulate Nociceptive Sensation and Emotional Motivation in Diabetic Neuropathic Pain. J Neurosci 2022; 42:8184-8199. [PMID: 36109166 PMCID: PMC9636999 DOI: 10.1523/jneurosci.0920-22.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 09/06/2022] [Accepted: 09/11/2022] [Indexed: 11/21/2022] Open
Abstract
Diabetic neuropathic pain (DNP) is a diabetes complication experienced by many patients. Ventrolateral periaqueductal gray (vlPAG) neurons are essential mediators of the descending pain modulation system, yet the role of vlPAG astrocytes in DNP remains unclear. The present study applied a multidimensional approach to elucidate the role of these astrocytes in DNP. We verified the activation of astrocytes in different regions of the PAG in male DNP-model rats. We found that only astrocytes in the vlPAG exhibited increased growth. Furthermore, we described differences in vlPAG astrocyte activity at different time points during DNP progression. After the 14th day of modeling, vlPAG astrocytes exhibited obvious activation and morphologic changes. Furthermore, activation of Gq-designer receptors exclusively activated by a designer drug (Gq-DREADDs) in vlPAG astrocytes in naive male rats induced neuropathic pain-like symptoms and pain-related aversion, whereas activation of Gi-DREADDs in vlPAG astrocytes in male DNP-model rats alleviated sensations of pain and promoted pain-related preference behavior. Thus, bidirectional manipulation of vlPAG astrocytes revealed their potential to regulate pain. Surprisingly, activation of Gi-DREADDs in vlPAG astrocytes also mitigated anxiety-like behavior induced by DNP. Thus, our results provide direct support for the hypothesis that vlPAG astrocytes regulate diabetes-associated neuropathic pain and concomitant anxiety-like behavior.SIGNIFICANCE STATEMENT Many studies examined the association between the ventrolateral periaqueductal gray (vlPAG) and neuropathic pain. However, few studies have focused on the role of vlPAG astrocytes in diabetic neuropathic pain (DNP) and DNP-related emotional changes. This work confirmed the role of vlPAG astrocytes in DNP by applying a more direct and robust approach. We used chemogenetics to bidirectionally manipulate the activity of vlPAG astrocytes and revealed that vlPAG astrocytes regulate DNP and pain-related behavior. In addition, we discovered that activation of Gi-designer receptors exclusively activated by a designer drug in vlPAG astrocytes alleviated anxiety-like behavior induced by DNP. Together, these findings provide new insights into DNP and concomitant anxiety-like behavior and supply new therapeutic targets for treating DNP.
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Affiliation(s)
- Lan Yang
- Department of Pharmacology, School of Pharmacy, Fujian Medical University, Fuzhou, 350122, Fujian China
| | - Jingshan Lu
- Department of Pharmacology, School of Pharmacy, Fujian Medical University, Fuzhou, 350122, Fujian China
- Fujian Center for Safety Evaluation of New Drug, Fujian Medical University, Fuzhou, 350122, Fujian China
| | - Jianpeng Guo
- Department of Pharmacology, School of Pharmacy, Fujian Medical University, Fuzhou, 350122, Fujian China
| | - Jian Chen
- Department of Pharmacology, School of Pharmacy, Fujian Medical University, Fuzhou, 350122, Fujian China
| | - Fangfang Xiong
- Department of Pharmacology, School of Pharmacy, Fujian Medical University, Fuzhou, 350122, Fujian China
| | - Xinyao Wang
- Department of Pharmacology, School of Pharmacy, Fujian Medical University, Fuzhou, 350122, Fujian China
| | - Li Chen
- Department of Pharmacology, School of Pharmacy, Fujian Medical University, Fuzhou, 350122, Fujian China
- Fujian Key Laboratory of Drug Target Discovery and Structural and Functional Research, Fujian Medical University, Fuzhou, 350122, Fujian China
| | - Changxi Yu
- Department of Pharmacology, School of Pharmacy, Fujian Medical University, Fuzhou, 350122, Fujian China
- Fujian Key Laboratory of Drug Target Discovery and Structural and Functional Research, Fujian Medical University, Fuzhou, 350122, Fujian China
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11
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Facilitation of Insulin Effects by Ranolazine in Astrocytes in Primary Culture. Int J Mol Sci 2022; 23:ijms231911969. [PMID: 36233271 PMCID: PMC9569909 DOI: 10.3390/ijms231911969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 09/23/2022] [Accepted: 09/28/2022] [Indexed: 11/16/2022] Open
Abstract
Ranolazine (Rn) is a drug used to treat persistent chronic coronary ischemia. It has also been shown to have therapeutic benefits on the central nervous system and an anti-diabetic effect by lowering blood glucose levels; however, no effects of Rn on cellular sensitivity to insulin (Ins) have been demonstrated yet. The present study aimed to investigate the permissive effects of Rn on the actions of Ins in astrocytes in primary culture. Ins (10−8 M), Rn (10−6 M), and Ins + Rn (10−8 M and 10−6 M, respectively) were added to astrocytes for 24 h. In comparison to control cells, Rn and/or Ins caused modifications in cell viability and proliferation. Rn increased protein expression of Cu/Zn-SOD and the pro-inflammatory protein COX-2 was upregulated by Ins. On the contrary, no significant changes were found in the protein expression of NF-κB and IκB. The presence of Rn produced an increase in p-ERK protein and a significant decrease in COX-2 protein expression. Furthermore, Rn significantly increased the effects of Ins on the expression of p-AKT, p-eNOS, p-ERK, Mn-SOD, and PPAR-γ. In addition, Rn + Ins produced a significant decrease in COX-2 expression. In conclusion, Rn facilitated the effects of insulin on the p-AKT, p-eNOS, p-ERK, Mn-SOD, and PPAR-γ signaling pathways, as well as on the anti-inflammatory and antioxidant effects of the hormone.
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12
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Kruyer A. Astrocyte Heterogeneity in Regulation of Synaptic Activity. Cells 2022; 11:cells11193135. [PMID: 36231097 PMCID: PMC9562199 DOI: 10.3390/cells11193135] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/02/2022] [Accepted: 10/02/2022] [Indexed: 02/07/2023] Open
Abstract
Our awareness of the number of synapse regulatory functions performed by astroglia is rapidly expanding, raising interesting questions regarding astrocyte heterogeneity and specialization across brain regions. Whether all astrocytes are poised to signal in a multitude of ways, or are instead tuned to surrounding synapses and how astroglial signaling is altered in psychiatric and cognitive disorders are fundamental questions for the field. In recent years, molecular and morphological characterization of astroglial types has broadened our ability to design studies to better analyze and manipulate specific functions of astroglia. Recent data emerging from these studies will be discussed in depth in this review. I also highlight remaining questions emerging from new techniques recently applied toward understanding the roles of astrocytes in synapse regulation in the adult brain.
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Affiliation(s)
- Anna Kruyer
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA
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13
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Wang J, Beecher K, Chehrehasa F, Moody H. The limitations of investigating appetite through circuit manipulations: are we biting off more than we can chew? Rev Neurosci 2022; 34:295-311. [PMID: 36054842 DOI: 10.1515/revneuro-2022-0072] [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: 06/14/2022] [Accepted: 07/09/2022] [Indexed: 11/15/2022]
Abstract
Disordered eating can underpin a number of debilitating and prevalent chronic diseases, such as obesity. Broader advances in psychopharmacology and biology have motivated some neuroscientists to address diet-induced obesity through reductionist, pre-clinical eating investigations on the rodent brain. Specifically, chemogenetic and optogenetic methods developed in the 21st century allow neuroscientists to perform in vivo, region-specific/projection-specific/promoter-specific circuit manipulations and immediately assess the impact of these manipulations on rodent feeding. These studies are able to rigorously conclude whether a specific neuronal population regulates feeding behaviour in the hope of eventually developing a mechanistic neuroanatomical map of appetite regulation. However, an artificially stimulated/inhibited rodent neuronal population that changes feeding behaviour does not necessarily represent a pharmacological target for treating eating disorders in humans. Chemogenetic/optogenetic findings must therefore be triangulated with the array of theories that contribute to our understanding of appetite. The objective of this review is to provide a wide-ranging discussion of the limitations of chemogenetic/optogenetic circuit manipulation experiments in rodents that are used to investigate appetite. Stepping into and outside of medical science epistemologies, this paper draws on philosophy of science, nutrition, addiction biology and neurophilosophy to prompt more integrative, transdisciplinary interpretations of chemogenetic/optogenetic appetite data. Through discussing the various technical and epistemological limitations of these data, we provide both an overview of chemogenetics and optogenetics accessible to non-neuroscientist obesity researchers, as well as a resource for neuroscientists to expand the number of lenses through which they interpret their circuit manipulation findings.
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Affiliation(s)
- Joshua Wang
- School of Clinical Sciences, Faculty of Health, Queensland University of Technology, 2 George Street, Brisbane 4000, QLD, Australia
| | - Kate Beecher
- UQ Centre for Clinical Research, Faculty of Medicine, University of Queensland, Building 71/918 Royal Brisbane and Women's Hospital Campus, Herston 4029, QLD, Australia
| | - Fatemeh Chehrehasa
- School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, 2 George Street, Brisbane 4000, QLD, Australia
| | - Hayley Moody
- Queensland University of Technology, 2 George Street, Brisbane 4000, QLD, Australia
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14
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Holt MK. The ins and outs of the caudal nucleus of the solitary tract: An overview of cellular populations and anatomical connections. J Neuroendocrinol 2022; 34:e13132. [PMID: 35509189 PMCID: PMC9286632 DOI: 10.1111/jne.13132] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 02/25/2022] [Accepted: 03/22/2022] [Indexed: 11/29/2022]
Abstract
The body and brain are in constant two-way communication. Driving this communication is a region in the lower brainstem: the dorsal vagal complex. Within the dorsal vagal complex, the caudal nucleus of the solitary tract (cNTS) is a major first stop for incoming information from the body to the brain carried by the vagus nerve. The anatomy of this region makes it ideally positioned to respond to signals of change in both emotional and bodily states. In turn, the cNTS controls the activity of regions throughout the brain that are involved in the control of both behaviour and physiology. This review is intended to help anyone with an interest in the cNTS. First, I provide an overview of the architecture of the cNTS and outline the wide range of neurotransmitters expressed in subsets of neurons in the cNTS. Next, in detail, I discuss the known inputs and outputs of the cNTS and briefly highlight what is known regarding the neurochemical makeup and function of those connections. Then, I discuss one group of cNTS neurons: glucagon-like peptide-1 (GLP-1)-expressing neurons. GLP-1 neurons serve as a good example of a group of cNTS neurons, which receive input from varied sources and have the ability to modulate both behaviour and physiology. Finally, I consider what we might learn about other cNTS neurons from our study of GLP-1 neurons and why it is important to remember that the manipulation of molecularly defined subsets of cNTS neurons is likely to affect physiology and behaviours beyond those monitored in individual experiments.
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Affiliation(s)
- Marie K. Holt
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUK
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15
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Lawal O, Ulloa Severino FP, Eroglu C. The role of astrocyte structural plasticity in regulating neural circuit function and behavior. Glia 2022; 70:1467-1483. [PMID: 35535566 PMCID: PMC9233050 DOI: 10.1002/glia.24191] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 04/28/2022] [Accepted: 04/28/2022] [Indexed: 12/12/2022]
Abstract
Brain circuits undergo substantial structural changes during development, driven by the formation, stabilization, and elimination of synapses. Synaptic connections continue to undergo experience‐dependent structural rearrangements throughout life, which are postulated to underlie learning and memory. Astrocytes, a major glial cell type in the brain, are physically in contact with synaptic circuits through their structural ensheathment of synapses. Astrocytes strongly contribute to the remodeling of synaptic structures in healthy and diseased central nervous systems by regulating synaptic connectivity and behaviors. However, whether structural plasticity of astrocytes is involved in their critical functions at the synapse is unknown. This review will discuss the emerging evidence linking astrocytic structural plasticity to synaptic circuit remodeling and regulation of behaviors. Moreover, we will survey possible molecular and cellular mechanisms regulating the structural plasticity of astrocytes and their non‐cell‐autonomous effects on neuronal plasticity. Finally, we will discuss how astrocyte morphological changes in different physiological states and disease conditions contribute to neuronal circuit function and dysfunction.
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Affiliation(s)
- Oluwadamilola Lawal
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA.,Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Francesco Paolo Ulloa Severino
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA.,Department of Neuroscience and Psychology, Duke University, Durham, North Carolina, USA.,Howard Hughes Medical Institute, Duke University, Durham, North Carolina, USA
| | - Cagla Eroglu
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA.,Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, USA.,Howard Hughes Medical Institute, Duke University, Durham, North Carolina, USA.,Duke Institute for Brain Sciences, Durham, North Carolina, USA
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16
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Glial Modulation of Energy Balance: The Dorsal Vagal Complex Is No Exception. Int J Mol Sci 2022; 23:ijms23020960. [PMID: 35055143 PMCID: PMC8779587 DOI: 10.3390/ijms23020960] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/11/2022] [Accepted: 01/13/2022] [Indexed: 02/04/2023] Open
Abstract
The avoidance of being overweight or obese is a daily challenge for a growing number of people. The growing proportion of people suffering from a nutritional imbalance in many parts of the world exemplifies this challenge and emphasizes the need for a better understanding of the mechanisms that regulate nutritional balance. Until recently, research on the central regulation of food intake primarily focused on neuronal signaling, with little attention paid to the role of glial cells. Over the last few decades, our understanding of glial cells has changed dramatically. These cells are increasingly regarded as important neuronal partners, contributing not just to cerebral homeostasis, but also to cerebral signaling. Our understanding of the central regulation of energy balance is part of this (r)evolution. Evidence is accumulating that glial cells play a dynamic role in the modulation of energy balance. In the present review, we summarize recent data indicating that the multifaceted glial compartment of the brainstem dorsal vagal complex (DVC) should be considered in research aimed at identifying feeding-related processes operating at this level.
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17
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Lyon KA, Allen NJ. From Synapses to Circuits, Astrocytes Regulate Behavior. Front Neural Circuits 2022; 15:786293. [PMID: 35069124 PMCID: PMC8772456 DOI: 10.3389/fncir.2021.786293] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/05/2021] [Indexed: 12/21/2022] Open
Abstract
Astrocytes are non-neuronal cells that regulate synapses, neuronal circuits, and behavior. Astrocytes ensheath neuronal synapses to form the tripartite synapse where astrocytes influence synapse formation, function, and plasticity. Beyond the synapse, recent research has revealed that astrocyte influences on the nervous system extend to the modulation of neuronal circuitry and behavior. Here we review recent findings on the active role of astrocytes in behavioral modulation with a focus on in vivo studies, primarily in mice. Using tools to acutely manipulate astrocytes, such as optogenetics or chemogenetics, studies reviewed here have demonstrated a causal role for astrocytes in sleep, memory, sensorimotor behaviors, feeding, fear, anxiety, and cognitive processes like attention and behavioral flexibility. Current tools and future directions for astrocyte-specific manipulation, including methods for probing astrocyte heterogeneity, are discussed. Understanding the contribution of astrocytes to neuronal circuit activity and organismal behavior will be critical toward understanding how nervous system function gives rise to behavior.
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Affiliation(s)
- Krissy A Lyon
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, United States
| | - Nicola J Allen
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, United States
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18
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Doust YV, Sumargo N, Ziebell JM, Premilovac D. Insulin Resistance in the Brain: Evidence Supporting a Role for Inflammation, Reactive Microglia, and the Impact of Biological Sex. Neuroendocrinology 2022; 112:1027-1038. [PMID: 35279657 DOI: 10.1159/000524059] [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: 12/22/2021] [Accepted: 03/02/2022] [Indexed: 11/19/2022]
Abstract
Increased intake of highly processed, energy-dense foods combined with a sedentary lifestyle are helping fuel the current overweight and obesity crisis, which is more prevalent in women than in men. Although peripheral organs such as adipose tissue contribute to the physiological development of obesity, emerging work aims to understand the role of the central nervous system to whole-body energy homeostasis and development of weight gain and obesity. The present review discusses the impact of insulin, insulin resistance, free fatty acids, and inflammation on brain function and how these differ between the males and females in the context of obesity. We highlight the potential of microglia, the resident immune cells in the brain, as mediators of neuronal insulin resistance that drive reduced satiety, increased food intake, and thus, obesity.
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Affiliation(s)
- Yasmine V Doust
- Wicking Dementia Research and Education Centre, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Nicole Sumargo
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Jenna M Ziebell
- Wicking Dementia Research and Education Centre, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Dino Premilovac
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
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19
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Frintrop L, Trinh S, Seitz J, Kipp M. The Role of Glial Cells in Regulating Feeding Behavior: Potential Relevance to Anorexia Nervosa. J Clin Med 2021; 11:jcm11010186. [PMID: 35011927 PMCID: PMC8745326 DOI: 10.3390/jcm11010186] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/17/2021] [Accepted: 12/25/2021] [Indexed: 12/16/2022] Open
Abstract
Eating behavior is controlled by hypothalamic circuits in which agouti-related peptide-expressing neurons when activated in the arcuate nucleus, promote food intake while pro-opiomelanocortin-producing neurons promote satiety. The respective neurotransmitters signal to other parts of the hypothalamus such as the paraventricular nucleus as well as several extra-hypothalamic brain regions to orchestrate eating behavior. This complex process of food intake may be influenced by glia cells, in particular astrocytes and microglia. Recent studies showed that GFAP+ astrocyte cell density is reduced in the central nervous system of an experimental anorexia nervosa model. Anorexia nervosa is an eating disorder that causes, among the well-known somatic symptoms, brain volume loss which was associated with neuropsychological deficits while the underlying pathophysiology is unknown. In this review article, we summarize the findings of glia cells in anorexia nervosa animal models and try to deduce which role glia cells might play in the pathophysiology of eating disorders, including anorexia nervosa. A better understanding of glia cell function in the regulation of food intake and eating behavior might lead to the identification of new drug targets.
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Affiliation(s)
- Linda Frintrop
- Institute of Anatomy, Rostock University Medical Center, 18057 Rostock, Germany;
- Correspondence: ; Tel.: +49-(0)-381-494-8406
| | - Stefanie Trinh
- Institute of Neuroanatomy, RWTH Aachen University, 52074 Aachen, Germany;
| | - Jochen Seitz
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, RWTH Aachen University, 52074 Aachen, Germany;
| | - Markus Kipp
- Institute of Anatomy, Rostock University Medical Center, 18057 Rostock, Germany;
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20
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Ohlig S, Clavreul S, Thorwirth M, Simon-Ebert T, Bocchi R, Ulbricht S, Kannayian N, Rossner M, Sirko S, Smialowski P, Fischer-Sternjak J, Götz M. Molecular diversity of diencephalic astrocytes reveals adult astrogenesis regulated by Smad4. EMBO J 2021; 40:e107532. [PMID: 34549820 PMCID: PMC8561644 DOI: 10.15252/embj.2020107532] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 08/09/2021] [Accepted: 08/19/2021] [Indexed: 12/16/2022] Open
Abstract
Astrocytes regulate brain‐wide functions and also show region‐specific differences, but little is known about how general and region‐specific functions are aligned at the single‐cell level. To explore this, we isolated adult mouse diencephalic astrocytes by ACSA‐2‐mediated magnetic‐activated cell sorting (MACS). Single‐cell RNA‐seq revealed 7 gene expression clusters of astrocytes, with 4 forming a supercluster. Within the supercluster, cells differed by gene expression related to ion homeostasis or metabolism, with the former sharing gene expression with other regions and the latter being restricted to specific regions. All clusters showed expression of proliferation‐related genes, and proliferation of diencephalic astrocytes was confirmed by immunostaining. Clonal analysis demonstrated low level of astrogenesis in the adult diencephalon, but not in cerebral cortex grey matter. This led to the identification of Smad4 as a key regulator of diencephalic astrocyte in vivo proliferation and in vitro neurosphere formation. Thus, astrocytes show diverse gene expression states related to distinct functions with some subsets being more widespread while others are more regionally restricted. However, all share low‐level proliferation revealing the novel concept of adult astrogenesis in the diencephalon.
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Affiliation(s)
- Stefanie Ohlig
- Biomedical Center (BMC), Division of Physiological Genomics, Faculty of Medicine, LMU Munich, Munich, Germany.,Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Neuherberg, Germany
| | - Solène Clavreul
- Biomedical Center (BMC), Division of Physiological Genomics, Faculty of Medicine, LMU Munich, Munich, Germany.,Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Neuherberg, Germany
| | - Manja Thorwirth
- Biomedical Center (BMC), Division of Physiological Genomics, Faculty of Medicine, LMU Munich, Munich, Germany.,Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Neuherberg, Germany
| | - Tatiana Simon-Ebert
- Biomedical Center (BMC), Division of Physiological Genomics, Faculty of Medicine, LMU Munich, Munich, Germany.,Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Neuherberg, Germany
| | - Riccardo Bocchi
- Biomedical Center (BMC), Division of Physiological Genomics, Faculty of Medicine, LMU Munich, Munich, Germany.,Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Neuherberg, Germany
| | - Sabine Ulbricht
- Biomedical Center (BMC), Division of Physiological Genomics, Faculty of Medicine, LMU Munich, Munich, Germany.,Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Neuherberg, Germany
| | - Nirmal Kannayian
- Molecular Neurobiology, Department of Psychiatry, LMU Munich, Munich, Germany
| | - Moritz Rossner
- Molecular Neurobiology, Department of Psychiatry, LMU Munich, Munich, Germany
| | - Swetlana Sirko
- Biomedical Center (BMC), Division of Physiological Genomics, Faculty of Medicine, LMU Munich, Munich, Germany.,Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Neuherberg, Germany
| | - Pawel Smialowski
- Biomedical Center (BMC), Division of Physiological Genomics, Faculty of Medicine, LMU Munich, Munich, Germany.,Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Neuherberg, Germany
| | - Judith Fischer-Sternjak
- Biomedical Center (BMC), Division of Physiological Genomics, Faculty of Medicine, LMU Munich, Munich, Germany.,Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Neuherberg, Germany
| | - Magdalena Götz
- Biomedical Center (BMC), Division of Physiological Genomics, Faculty of Medicine, LMU Munich, Munich, Germany.,Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Neuherberg, Germany.,SYNERGY, Excellence cluster of Systems Neurology, LMU Munich, Munich, Germany
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21
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Sustained microglial activation in the area postrema of collagen-induced arthritis mice. Arthritis Res Ther 2021; 23:273. [PMID: 34715926 PMCID: PMC8556992 DOI: 10.1186/s13075-021-02657-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 10/12/2021] [Indexed: 02/07/2023] Open
Abstract
Background Central nervous system (CNS)-mediated symptoms, such as fatigue, depression, and hyperalgesia, are common complications among patients with rheumatoid arthritis (RA). However, it remains unclear how the peripheral pathology of RA spreads to the brain. Accumulated evidence showing an association between serum cytokine levels and aberrant CNS function suggests that humoral factors participate in this mechanism. In contrast to the well-known early responses of microglia (CNS-resident immune cells) in the area postrema [AP; a brain region lacking a blood–brain barrier (BBB)] to experimental inflammation, microglial alterations in the AP during chronic inflammation like RA remain unclear. Therefore, to determine whether microglia in the AP can react to persistent autoimmune-arthritis conditions, we analyzed these cells in a mouse model of collagen-induced arthritis (CIA). Methods Microglial number and morphology were analyzed in the AP of CIA and control mice (administered Freund’s adjuvant or saline). Immunostaining for ionized calcium-binding adaptor molecule-1 was performed at various disease phases: “pre-onset” [post-immunization day (PID) 21], “establishment” (PID 35), and “chronic” (PID 56 and 84). Quantitative analyses of microglial number and morphology were performed, with principal component analysis used to classify microglia. Interleukin-1β (IL-1β) mRNA expression was analyzed by multiple fluorescent in situ hybridization and real-time polymerase chain reaction. Behavioral changes were assessed by sucrose preference test. Results Microglia in the AP significantly increased in density and exhibited changes in morphology during the establishment and chronic phases, but not the pre-onset phase. Non-subjective clustering classification of cell morphology (CIA, 1,256 cells; saline, 852 cells) showed that the proportion of highly activated microglia increased in the CIA group during establishment and chronic phases. Moreover, the density of IL-1β-positive microglia, a hallmark of functional activation, was increased in the AP. Sucrose preferences in CIA mice negatively correlated with IL-1β expression in brain regions containing the AP. Conclusions Our findings demonstrate that microglia in the AP can sustain their activated state during persistent autoimmune arthritis, which suggests that chronic inflammation, such as RA, may affect microglia in brain regions lacking a BBB and have various neural consequences. Supplementary Information The online version contains supplementary material available at 10.1186/s13075-021-02657-x.
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22
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Astrocyte Gliotransmission in the Regulation of Systemic Metabolism. Metabolites 2021; 11:metabo11110732. [PMID: 34822390 PMCID: PMC8623475 DOI: 10.3390/metabo11110732] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 12/28/2022] Open
Abstract
Normal brain function highly relies on the appropriate functioning of astrocytes. These glial cells are strategically situated between blood vessels and neurons, provide significant substrate support to neuronal demand, and are sensitive to neuronal activity and energy-related molecules. Astrocytes respond to many metabolic conditions and regulate a wide array of physiological processes, including cerebral vascular remodeling, glucose sensing, feeding, and circadian rhythms for the control of systemic metabolism and behavior-related responses. This regulation ultimately elicits counterregulatory mechanisms in order to couple whole-body energy availability with brain function. Therefore, understanding the role of astrocyte crosstalk with neighboring cells via the release of molecules, e.g., gliotransmitters, into the parenchyma in response to metabolic and neuronal cues is of fundamental relevance to elucidate the distinct roles of these glial cells in the neuroendocrine control of metabolism. Here, we review the mechanisms underlying astrocyte-released gliotransmitters that have been reported to be crucial for maintaining homeostatic regulation of systemic metabolism.
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Cui QN, Stein LM, Fortin SM, Hayes MR. The role of glia in the physiology and pharmacology of GLP-1: Implications for obesity, diabetes, and neurodegenerative processes including glaucoma. Br J Pharmacol 2021; 179:715-726. [PMID: 34519040 PMCID: PMC8820182 DOI: 10.1111/bph.15683] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 08/17/2021] [Accepted: 08/27/2021] [Indexed: 11/28/2022] Open
Abstract
The medical application of glucagon-like peptide-1 receptor (GLP-1R) agonists is ever-growing in scope, highlighting the urgent need for a comprehensive understanding of the mechanisms through which GLP-1R activation impacts physiology and behavior. A new wave of research aims to elucidate the role GLP-1R signaling in glia plays in regulating energy balance, glycemic control, neuroinflammation, and oxidative stress. Once controversial, existing evidence now suggests that subsets of glia (e.g., microglia, tanycytes, and astrocytes) and infiltrating macrophages express GLP-1R. In this review, we discuss the implications of these findings, with particular focus on the utility of both clinically available and novel GLP-1R agonists for treating metabolic and neurodegenerative diseases, enhancing cognition, and combating substance abuse.
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Affiliation(s)
- Qi N Cui
- Scheie Eye Institute, University of Pennsylvania
| | - Lauren M Stein
- Department of Psychiatry Perelman School of Medicine, University of Pennsylvania
| | - Samantha M Fortin
- Department of Psychiatry Perelman School of Medicine, University of Pennsylvania
| | - Matthew R Hayes
- Department of Psychiatry Perelman School of Medicine, University of Pennsylvania
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24
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Hofmann GC, Hasser EM, Kline DD. Unilateral vagotomy alters astrocyte and microglial morphology in the nucleus tractus solitarii of the rat. Am J Physiol Regul Integr Comp Physiol 2021; 320:R945-R959. [PMID: 33978480 PMCID: PMC8285617 DOI: 10.1152/ajpregu.00019.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/09/2021] [Accepted: 05/04/2021] [Indexed: 12/11/2022]
Abstract
The nucleus tractus solitarii (nTS) is the initial site of integration of sensory information from the cardiorespiratory system and contributes to reflex responses to hypoxia. Afferent fibers of the bilateral vagus nerves carry input from the heart, lungs, and other organs to the nTS where it is processed and modulated. Vagal afferents and nTS neurons are integrally associated with astrocytes and microglia that contribute to neuronal activity and influence cardiorespiratory control. We hypothesized that vagotomy would alter glial morphology and cardiorespiratory responses to hypoxia. Unilateral vagotomy (or sham surgery) was performed in rats. Prior to and seven days after surgery, baseline and hypoxic cardiorespiratory responses were monitored in conscious and anesthetized animals. The brainstem was sectioned and caudal, mid-area postrema (mid-AP), and rostral sections of the nTS were prepared for immunohistochemistry. Vagotomy increased immunoreactivity (-IR) of astrocytic glial fibrillary acidic protein (GFAP), specifically at mid-AP in the nTS. Similar results were found in the dorsal motor nucleus of the vagus (DMX). Vagotomy did not alter nTS astrocyte number, yet increased astrocyte branching and altered morphology. In addition, vagotomy both increased nTS microglia number and produced morphologic changes indicative of activation. Cardiorespiratory baseline parameters and hypoxic responses remained largely unchanged, but vagotomized animals displayed fewer augmented breaths (sighs) in response to hypoxia. Altogether, vagotomy alters nTS glial morphology, indicative of functional changes in astrocytes and microglia that may affect cardiorespiratory function in health and disease.
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Affiliation(s)
- Gabrielle C Hofmann
- Comparative Medicine, University of Missouri, Columbia, Missouri
- Area Pathobiology, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Eileen M Hasser
- Area Pathobiology, University of Missouri, Columbia, Missouri
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - David D Kline
- Area Pathobiology, University of Missouri, Columbia, Missouri
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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25
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Clyburn C, Browning KN. Glutamatergic plasticity within neurocircuits of the dorsal vagal complex and the regulation of gastric functions. Am J Physiol Gastrointest Liver Physiol 2021; 320:G880-G887. [PMID: 33730858 PMCID: PMC8202199 DOI: 10.1152/ajpgi.00014.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The meticulous regulation of the gastrointestinal (GI) tract is required for the coordination of gastric motility and emptying, intestinal secretion, absorption, and transit as well as for the overarching management of food intake and energy homeostasis. Disruption of GI functions is associated with the development of severe GI disorders and the alteration of food intake and caloric balance. Functional GI disorders as well as the dysregulation of energy balance and food intake are frequently associated with, or result from, alterations in the central regulation of GI control. The faithful and rapid transmission of information from the stomach and upper GI tract to second-order neurons of the nucleus of the tractus solitarius (NTS) relies on the delicate modulation of excitatory glutamatergic transmission, as does the relay of integrated signals from the NTS to parasympathetic efferent neurons of the dorsal motor nucleus of the vagus (DMV). Many studies have focused on understanding the physiological and pathophysiological modulation of these glutamatergic synapses, although their role in the control and regulation of GI functions has lagged behind that of cardiovascular and respiratory functions. The purpose of this review is to examine the current literature exploring the role of glutamatergic transmission in the DVC in the regulation of GI functions.
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Affiliation(s)
- Courtney Clyburn
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, Pennsylvania
| | - Kirsteen N. Browning
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, Pennsylvania
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26
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Broadhead MJ, Miles GB. A common role for astrocytes in rhythmic behaviours? Prog Neurobiol 2021; 202:102052. [PMID: 33894330 DOI: 10.1016/j.pneurobio.2021.102052] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 03/03/2021] [Accepted: 04/13/2021] [Indexed: 01/16/2023]
Abstract
Astrocytes are a functionally diverse form of glial cell involved in various aspects of nervous system infrastructure, from the metabolic and structural support of neurons to direct neuromodulation of synaptic activity. Investigating how astrocytes behave in functionally related circuits may help us understand whether there is any conserved logic to the role of astrocytes within neuronal networks. Astrocytes are implicated as key neuromodulatory cells within neural circuits that control a number of rhythmic behaviours such as breathing, locomotion and circadian sleep-wake cycles. In this review, we examine the evidence that astrocytes are directly involved in the regulation of the neural circuits underlying six different rhythmic behaviours: locomotion, breathing, chewing, gastrointestinal motility, circadian sleep-wake cycles and oscillatory feeding behaviour. We discuss how astrocytes are integrated into the neuronal networks that regulate these behaviours, and identify the potential gliotransmission signalling mechanisms involved. From reviewing the evidence of astrocytic involvement in a range of rhythmic behaviours, we reveal a heterogenous array of gliotransmission mechanisms, which help to regulate neuronal networks. However, we also observe an intriguing thread of commonality, in the form of purinergic gliotransmission, which is frequently utilised to facilitate feedback inhibition within rhythmic networks to constrain a given behaviour within its operational range.
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Affiliation(s)
- Matthew J Broadhead
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK.
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
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27
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González-García I, Gruber T, García-Cáceres C. Insulin action on astrocytes: From energy homeostasis to behaviour. J Neuroendocrinol 2021; 33:e12953. [PMID: 33724579 DOI: 10.1111/jne.12953] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 12/14/2022]
Abstract
Astrocytes are specialised glial cells that integrate distinct inputs arising from neurones, other glial cells and the microcirculation to regulate diverse aspects of brain function. A growing body of emerging evidence supports that astrocytes, similar to neurones, also play active roles in the neuroendocrine control of metabolism by responding to afferent nutritional and hormonal cues and translating these metabolic cues into neuronal inputs. Specifically, insulin action in astrocytes has received special emphasis given its newly discovered regulatory role in brain glucose uptake, which until recently was assumed to be an insulin independent process. We now know that insulin signalling in astrocytes regulates metabolic processes and behavioural responses through coupling brain glucose uptake with nutrient availability to maintain energy balance and systemic glucose homeostasis. Moreover, genetic ablation of the insulin receptor in astrocytes is associated with anxiety- and depressive-like behaviours, confirming that these glial cells are involved in the regulation of cognition and mood via insulin action. Here, we provide a comprehensive review of the most relevant findings that have been made over the course of the last few years linking insulin signalling in astrocytes with the pathogenesis of brain metabolic and neurodegenerative diseases; a still unexplored field, but with a high translational potential for developing therapies.
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Affiliation(s)
- Ismael González-García
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Tim Gruber
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Cristina García-Cáceres
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Medizinische Klinik and Poliklinik IV, Klinikum der Universität, Ludwig-Maximilians-Universität München, Munich, Germany
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28
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Martinez D, Kline DD. The role of astrocytes in the nucleus tractus solitarii in maintaining central control of autonomic function. Am J Physiol Regul Integr Comp Physiol 2021; 320:R418-R424. [PMID: 33439770 PMCID: PMC8238142 DOI: 10.1152/ajpregu.00254.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/16/2020] [Accepted: 01/07/2021] [Indexed: 12/24/2022]
Abstract
The nucleus tractus solitarii (nTS) is the first central site for the termination and integration of autonomic and respiratory sensory information. Sensory afferents terminating in the nTS as well as the embedded nTS neurocircuitry release and utilize glutamate that is critical for maintenance of baseline cardiorespiratory parameters and initiating cardiorespiratory reflexes, including those activated by bouts of hypoxia. nTS astrocytes contribute to synaptic and neuronal activity through a variety of mechanisms, including gliotransmission and regulation of glutamate in the extracellular space via membrane-bound transporters. Here, we aim to highlight recent evidence for the role of astrocytes within the nTS and their regulation of autonomic and cardiorespiratory processes under normal and hypoxic conditions.
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Affiliation(s)
- Diana Martinez
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - David D Kline
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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29
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Vaidyanathan TV, Collard M, Yokoyama S, Reitman ME, Poskanzer KE. Cortical astrocytes independently regulate sleep depth and duration via separate GPCR pathways. eLife 2021; 10:63329. [PMID: 33729913 PMCID: PMC7968927 DOI: 10.7554/elife.63329] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 02/17/2021] [Indexed: 12/11/2022] Open
Abstract
Non-rapid eye movement (NREM) sleep, characterized by slow-wave electrophysiological activity, underlies several critical functions, including learning and memory. However, NREM sleep is heterogeneous, varying in duration, depth, and spatially across the cortex. While these NREM sleep features are thought to be largely independently regulated, there is also evidence that they are mechanistically coupled. To investigate how cortical NREM sleep features are controlled, we examined the astrocytic network, comprising a cortex-wide syncytium that influences population-level neuronal activity. We quantified endogenous astrocyte activity in mice over natural sleep and wake, then manipulated specific astrocytic G-protein-coupled receptor (GPCR) signaling pathways in vivo. We find that astrocytic Gi- and Gq-coupled GPCR signaling separately control NREM sleep depth and duration, respectively, and that astrocytic signaling causes differential changes in local and remote cortex. These data support a model in which the cortical astrocyte network serves as a hub for regulating distinct NREM sleep features. Sleep has many roles, from strengthening new memories to regulating mood and appetite. While we might instinctively think of sleep as a uniform state of reduced brain activity, the reality is more complex. First, over the course of the night, we cycle between a number of different sleep stages, which reflect different levels of sleep depth. Second, the amount of sleep depth is not necessarily even across the brain but can vary between regions. These sleep stages consist of either rapid eye movement (REM) sleep or non-REM (NREM) sleep. REM sleep is when most dreaming occurs, whereas NREM sleep is particularly important for learning and memory and can vary in duration and depth. During NREM sleep, large groups of neurons synchronize their firing to create rhythmic waves of activity known as slow waves. The more synchronous the activity, the deeper the sleep. Vaidyanathan et al. now show that brain cells called astrocytes help regulate NREM sleep. Astrocytes are not neurons but belong to a group of specialized cells called glia. They are the largest glia cell type in the brain and display an array of proteins on their surfaces called G-protein-coupled receptors (GPCRs). These enable them to sense sleep-wake signals from other parts of the brain and to generate their own signals. In fact, each astrocyte can communicate with thousands of neurons at once. They are therefore well-poised to coordinate brain activity during NREM sleep. Using innovative tools, Vaidyanathan et al. visualized astrocyte activity in mice as the animals woke up or fell asleep. The results showed that astrocytes change their activity just before each sleep–wake transition. They also revealed that astrocytes control both the depth and duration of NREM sleep via two different types of GPCR signals. Increasing one of these signals (Gi-GPCR) made the mice sleep more deeply but did not change sleep duration. Decreasing the other (Gq-GPCR) made the mice sleep for longer but did not affect sleep depth. Sleep problems affect many people at some point in their lives, and often co-exist with other conditions such as mental health disorders. Understanding how the brain regulates different features of sleep could help us develop better – and perhaps more specific – treatments for sleep disorders. The current study suggests that manipulating GPCRs on astrocytes might increase sleep depth, for example. But before work to test this idea can begin, we must first determine whether findings from sleeping mice also apply to people.
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Affiliation(s)
- Trisha V Vaidyanathan
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, United States
| | - Max Collard
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, United States
| | - Sae Yokoyama
- Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, United States
| | - Michael E Reitman
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, United States
| | - Kira E Poskanzer
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, San Francisco, United States
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30
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Li J, Deng S, He Q, Ke W, Shu Y. Asynchronous Glutamate Release at Autapses Regulates Spike Reliability and Precision in Mouse Neocortical Pyramidal Cells. Cereb Cortex 2021; 31:2278-2290. [PMID: 33279969 DOI: 10.1093/cercor/bhaa361] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 11/13/2022] Open
Abstract
Autapses are self-synapses of a neuron. Inhibitory autapses in the neocortex release GABA in 2 modes, synchronous release and asynchronous release (AR), providing precise and prolonged self-inhibition, respectively. A subpopulation of neocortical pyramidal cells (PCs) also forms functional autapses, activation of which promotes burst firing by strong unitary autaptic response that reflects synchronous glutamate release. However, it remains unclear whether AR occurs at PC autapses and plays a role in neuronal signaling. We performed whole-cell recordings from layer-5 PCs in slices of mouse prefrontal cortex (PFC). In response to action potential (AP) burst, 63% of PCs showed robust long-lasting autaptic AR, much stronger than synaptic AR between neighboring PCs. The autaptic AR is mediated predominantly by P/Q-type Ca2+ channels, and its strength depends on the intensity of PC activity and the level of residual Ca2+. Further experiments revealed that autaptic AR enhances spiking activities but reduces the temporal precision of post-burst APs. Together, the results show the occurrence of AR at PC autapses, the delayed and persistent glutamate AR causes self-excitation in individual PCs but may desynchronize the autaptic PC population. Thus, glutamatergic autapses should be essential elements in PFC and contribute to cortical information processing.
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Affiliation(s)
- Junlong Li
- State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
| | - Suixin Deng
- Department of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Quansheng He
- Department of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Wei Ke
- Department of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Yousheng Shu
- Department of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200032, China
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Salmina AB, Gorina YV, Erofeev AI, Balaban PM, Bezprozvanny IB, Vlasova OL. Optogenetic and chemogenetic modulation of astroglial secretory phenotype. Rev Neurosci 2021; 32:459-479. [PMID: 33550788 DOI: 10.1515/revneuro-2020-0119] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 11/28/2020] [Indexed: 12/20/2022]
Abstract
Astrocytes play a major role in brain function and alterations in astrocyte function that contribute to the pathogenesis of many brain disorders. The astrocytes are attractive cellular targets for neuroprotection and brain tissue regeneration. Development of novel approaches to monitor and to control astroglial function is of great importance for further progress in basic neurobiology and in clinical neurology, as well as psychiatry. Recently developed advanced optogenetic and chemogenetic techniques enable precise stimulation of astrocytes in vitro and in vivo, which can be achieved by the expression of light-sensitive channels and receptors, or by expression of receptors exclusively activated by designer drugs. Optogenetic stimulation of astrocytes leads to dramatic changes in intracellular calcium concentrations and causes the release of gliotransmitters. Optogenetic and chemogenetic protocols for astrocyte activation aid in extracting novel information regarding the function of brain's neurovascular unit. This review summarizes current data obtained by this approach and discusses a potential mechanistic connection between astrocyte stimulation and changes in brain physiology.
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Affiliation(s)
- Alla B Salmina
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
- Research Institute of Molecular Medicine and Pathobiochemistry, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| | - Yana V Gorina
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
- Research Institute of Molecular Medicine and Pathobiochemistry, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| | - Alexander I Erofeev
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
| | - Pavel M Balaban
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
- Laboratory of Cellular Neurobiology of Learning, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Ilya B Bezprozvanny
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Olga L Vlasova
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
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Divide et impera: How mitochondrial fission in astrocytes rules obesity. Mol Metab 2021; 45:101159. [PMID: 33400974 PMCID: PMC7820126 DOI: 10.1016/j.molmet.2020.101159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/27/2020] [Accepted: 12/28/2020] [Indexed: 12/13/2022] Open
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Patel B, New LE, Griffiths JC, Deuchars J, Filippi BM. Inhibition of mitochondrial fission and iNOS in the dorsal vagal complex protects from overeating and weight gain. Mol Metab 2020; 43:101123. [PMID: 33227495 PMCID: PMC7753200 DOI: 10.1016/j.molmet.2020.101123] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVES The dorsal vagal complex (DVC) senses insulin and controls glucose homeostasis, feeding behaviour and body weight. Three-days of high-fat diet (HFD) in rats are sufficient to induce insulin resistance in the DVC and impair its ability to regulate feeding behaviour. HFD-feeding is associated with increased dynamin-related protein 1 (Drp1)-dependent mitochondrial fission in the DVC. We investigated the effects that altered Drp1 activity in the DVC has on feeding behaviour. Additionally, we aimed to uncover the molecular events and the neuronal cell populations associated with DVC insulin sensing and resistance. METHODS Eight-week-old male Sprague Dawley rats received DVC stereotactic surgery for brain infusion to facilitate the localised administration of insulin or viruses to express mutated forms of Drp1 or to knockdown inducible nitric oxide synthase (iNOS) in the NTS of the DVC. High-Fat diet feeding was used to cause insulin resistance and obesity. RESULTS We showed that Drp1 activation in the DVC increases weight gain in rats and Drp1 inhibition in HFD-fed rats reduced food intake, weight gain and adipose tissue. Rats expressing active Drp1 in the DVC had higher levels of iNOS and knockdown of DVC iNOS in HFD-fed rats led to a reduction of food intake, weight gain and adipose tissue. Finally, inhibiting mitochondrial fission in DVC astrocytes was sufficient to protect rats from HFD-dependent insulin resistance, hyperphagia, weight gain and fat deposition. CONCLUSION We uncovered new molecular and cellular targets for brain regulation of whole-body metabolism, which could inform new strategies to combat obesity and diabetes.
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Affiliation(s)
- Bianca Patel
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, United Kingdom
| | - Lauryn E New
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, United Kingdom
| | - Joanne C Griffiths
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, United Kingdom
| | - Jim Deuchars
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, United Kingdom
| | - Beatrice M Filippi
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, United Kingdom.
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Haigh JL, New LE, Filippi BM. Mitochondrial Dynamics in the Brain Are Associated With Feeding, Glucose Homeostasis, and Whole-Body Metabolism. Front Endocrinol (Lausanne) 2020; 11:580879. [PMID: 33240218 PMCID: PMC7680879 DOI: 10.3389/fendo.2020.580879] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/05/2020] [Indexed: 12/13/2022] Open
Abstract
The brain is responsible for maintaining whole-body energy homeostasis by changing energy input and availability. The hypothalamus and dorsal vagal complex (DVC) are the primary sites of metabolic control, able to sense both hormones and nutrients and adapt metabolism accordingly. The mitochondria respond to the level of nutrient availability by fusion or fission to maintain energy homeostasis; however, these processes can be disrupted by metabolic diseases including obesity and type II diabetes (T2D). Mitochondrial dynamics are crucial in the development and maintenance of obesity and T2D, playing a role in the control of glucose homeostasis and whole-body metabolism across neurons and glia in the hypothalamus and DVC.
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Affiliation(s)
| | | | - Beatrice M. Filippi
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
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35
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Augusto-Oliveira M, Arrifano GP, Takeda PY, Lopes-Araújo A, Santos-Sacramento L, Anthony DC, Verkhratsky A, Crespo-Lopez ME. Astroglia-specific contributions to the regulation of synapses, cognition and behaviour. Neurosci Biobehav Rev 2020; 118:331-357. [DOI: 10.1016/j.neubiorev.2020.07.039] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 12/11/2022]
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36
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Blockade of Glial Connexin 43 Hemichannels Reduces Food Intake. Cells 2020; 9:cells9112387. [PMID: 33142723 PMCID: PMC7693394 DOI: 10.3390/cells9112387] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 10/20/2020] [Accepted: 10/26/2020] [Indexed: 12/16/2022] Open
Abstract
The metabolic syndrome, which comprises obesity and diabetes, is a major public health problem and the awareness of energy homeostasis control remains an important worldwide issue. The energy balance is finely regulated by the central nervous system (CNS), notably through neuronal networks, located in the hypothalamus and the dorsal vagal complex (DVC), which integrate nutritional, humoral and nervous information from the periphery. The glial cells’ contribution to these processes emerged few year ago. However, its underlying mechanism remains unclear. Glial connexin 43 hemichannels (Cx43 HCs) enable direct exchange with the extracellular space and can regulate neuronal network activity. In the present study, we sought to determine the possible involvement of glial Cx43 HCs in energy balance regulation. We here show that Cx43 is strongly expressed in the hypothalamus and DVC and is associated with glial cells. Remarkably, we observed a close apposition of Cx43 with synaptic elements in both the hypothalamus and DVC. Moreover, the expression of hypothalamic Cx43 mRNA and protein is modulated in response to fasting and diet-induced obesity. Functionally, we found that Cx43 HCs are largely open in the arcuate nucleus (ARC) from acute mice hypothalamic slices under basal condition, and significantly inhibited by TAT-GAP19, a mimetic peptide that specifically blocks Cx43 HCs activity. Moreover, intracerebroventricular (i.c.v.) TAT-GAP19 injection strongly decreased food intake, without further alteration of glycaemia, energy expenditures or locomotor activity. Using the immediate early gene c-Fos expression, we found that i.c.v. TAT-GAP19 injection induced neuronal activation in hypothalamic and brainstem nuclei dedicated to food intake regulation. Altogether, these results suggest a tonic delivery of orexigenic molecules associated with glial Cx43 HCs activity and a possible modulation of this tonus during fasting and obesity.
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Lebrun B, Barbot M, Tonon MC, Prévot V, Leprince J, Troadec JD. Glial endozepines and energy balance: Old peptides with new tricks. Glia 2020; 69:1079-1093. [PMID: 33105065 DOI: 10.1002/glia.23927] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 10/09/2020] [Accepted: 10/09/2020] [Indexed: 12/12/2022]
Abstract
The contribution of neuroglial interactions to the regulation of energy balance has gained increasing acceptance in recent years. In this context, endozepines, endogenous analogs of benzodiazepine derived from diazepam-binding inhibitor, are now emerging as major players. Produced by glial cells (astrocytes and tanycytes), endozepines have been known for two decades to exert potent anorexigenic effects by acting at the hypothalamic level. However, it is only recently that their modes of action, including the mechanisms by which they modulate energy metabolism, have begun to be elucidated. The data available today are abundant, significant, and sometimes contradictory, revealing a much more complex regulation than initially expected. Several mechanisms of action of endozepines seem to coexist at the central level, particularly in the hypothalamus. The brainstem has also recently emerged as a potential site of action for endozepines. In addition to their central anorexigenic effects, endozepines may also display peripheral effects promoting orexigenic actions, adding to their complexity and raising yet more questions. In this review, we attempt to provide an overview of our current knowledge in this rapidly evolving field and to pinpoint questions that remain unanswered.
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Affiliation(s)
- Bruno Lebrun
- CNRS 7291, Laboratoire de Neurosciences Cognitives, Aix Marseille University, Marseille, France
| | - Manon Barbot
- CNRS 7291, Laboratoire de Neurosciences Cognitives, Aix Marseille University, Marseille, France
| | - Marie-Christine Tonon
- INSERM U1239, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Normandie Université, Rouen, France
| | - Vincent Prévot
- University of Lille, INSERM, CHU Lille, Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience and Cognition, UMR-S 1172, European Genomic Institute of Diabetes (EGID), Lille, France
| | - Jérôme Leprince
- INSERM U1239, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Normandie Université, Rouen, France
| | - Jean-Denis Troadec
- CNRS 7291, Laboratoire de Neurosciences Cognitives, Aix Marseille University, Marseille, France
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Dyavanapalli J. Novel approaches to restore parasympathetic activity to the heart in cardiorespiratory diseases. Am J Physiol Heart Circ Physiol 2020; 319:H1153-H1161. [PMID: 33035444 DOI: 10.1152/ajpheart.00398.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neural control of the heart is regulated by sympathetic and parasympathetic divisions of the autonomic nervous system, both opposing each other to maintain cardiac homeostasis via regulating heart rate, conduction velocity, force of contraction, and coronary blood flow. Sympathetic hyperactivity and diminished parasympathetic activity are the characteristic features of many cardiovascular disease states including hypertension, myocardial ischemia, and arrhythmias that result in heart failure. Restoring parasympathetic activity to the heart has recently been identified as the promising approach to treat such conditions. However, approaches that used vagal nerve stimulation have been shown to be unsuccessful in heart failure. This review focuses on novel chemogenetic approaches used to identify the cardioprotective nature of activating neural points along the vagal pathway (both central and peripheral) while being selectively therapeutic in heart failure and obstructive sleep apnea.
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Affiliation(s)
- Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, George Washington University, Washington, District of Columbia
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Cansell C, Stobbe K, Sanchez C, Le Thuc O, Mosser CA, Ben-Fradj S, Leredde J, Lebeaupin C, Debayle D, Fleuriot L, Brau F, Devaux N, Benani A, Audinat E, Blondeau N, Nahon JL, Rovère C. Dietary fat exacerbates postprandial hypothalamic inflammation involving glial fibrillary acidic protein-positive cells and microglia in male mice. Glia 2020; 69:42-60. [PMID: 32659044 DOI: 10.1002/glia.23882] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 06/10/2020] [Accepted: 06/11/2020] [Indexed: 12/15/2022]
Abstract
In humans, obesity is associated with brain inflammation, glial reactivity, and immune cells infiltration. Studies in rodents have shown that glial reactivity occurs within 24 hr of high-fat diet (HFD) consumption, long before obesity development, and takes place mainly in the hypothalamus (HT), a crucial brain structure for controlling body weight. Here, we sought to characterize the postprandial HT inflammatory response to 1, 3, and 6 hr of exposure to either a standard diet (SD) or HFD. HFD exposure increased gene expression of astrocyte and microglial markers (glial fibrillary acidic protein [GFAP] and Iba1, respectively) compared to SD-treated mice and induced morphological modifications of microglial cells in HT. This remodeling was associated with higher expression of inflammatory genes and differential regulation of hypothalamic neuropeptides involved in energy balance regulation. DREADD and PLX5622 technologies, used to modulate GFAP-positive or microglial cells activity, respectively, showed that both glial cell types are involved in hypothalamic postprandial inflammation, with their own specific kinetics and reactiveness to ingested foods. Thus, recurrent exacerbated postprandial inflammation in the brain might promote obesity and needs to be characterized to address this worldwide crisis.
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Affiliation(s)
- Céline Cansell
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | - Katharina Stobbe
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | - Clara Sanchez
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | - Ophélia Le Thuc
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | - Coralie-Anne Mosser
- Laboratory of Neurophysiology and New Microscopies, INSERM, Université Paris Descartes, Paris, France
| | - Selma Ben-Fradj
- CSGA, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, Dijon, France
| | - Joris Leredde
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | | | - Delphine Debayle
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | - Lucile Fleuriot
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | - Frédéric Brau
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | - Nadège Devaux
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | - Alexandre Benani
- CSGA, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, Dijon, France
| | - Etienne Audinat
- IGF, CNRS, INSERM, Université de Montpellier, Montpellier, France
| | - Nicolas Blondeau
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | - Jean-Louis Nahon
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
| | - Carole Rovère
- IPMC, CNRS, Université Côte d'Azur, IPMC, CNRS, Valbonne, France
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MacDonald AJ, Ellacott KLJ. Astrocytes in the nucleus of the solitary tract: Contributions to neural circuits controlling physiology. Physiol Behav 2020; 223:112982. [PMID: 32535136 PMCID: PMC7378570 DOI: 10.1016/j.physbeh.2020.112982] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 05/04/2020] [Accepted: 05/22/2020] [Indexed: 12/12/2022]
Abstract
The nucleus of the solitary tract (NTS) is the primary brainstem centre for the integration of physiological information from the periphery transmitted via the vagus nerve. In turn, the NTS feeds into downstream circuits regulating physiological parameters. Astrocytes are glial cells which have key roles in maintaining CNS tissue homeostasis and regulating neuronal communication. Recently an increasing number of studies have implicated astrocytes in the regulation of synaptic transmission and physiology. This review aims to highlight evidence for a role for astrocytes in the functions of the NTS. Astrocytes maintain and modulate NTS synaptic transmission contributing to the control of diverse physiological systems namely cardiovascular, respiratory, glucoregulatory, and gastrointestinal. In addition, it appears these cells may have a role in central control of feeding behaviour. As such these cells are a key component of signal processing and physiological control by the NTS.
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Affiliation(s)
- Alastair J MacDonald
- Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Level 4, RILD, Barrack Rd, Exeter EX2 5DW, UK
| | - Kate L J Ellacott
- Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Level 4, RILD, Barrack Rd, Exeter EX2 5DW, UK.
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MacDonald AJ, Holmes FE, Beall C, Pickering AE, Ellacott KLJ. Regulation of food intake by astrocytes in the brainstem dorsal vagal complex. Glia 2019; 68:1241-1254. [PMID: 31880353 PMCID: PMC7187409 DOI: 10.1002/glia.23774] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 12/13/2019] [Accepted: 12/17/2019] [Indexed: 02/06/2023]
Abstract
A role for glial cells in brain circuits controlling feeding has begun to be identified with hypothalamic astrocyte signaling implicated in regulating energy homeostasis. The nucleus of the solitary tract (NTS), within the brainstem dorsal vagal complex (DVC), integrates vagal afferent information from the viscera and plays a role in regulating food intake. We hypothesized that astrocytes in this nucleus respond to, and influence, food intake. Mice fed high‐fat chow for 12 hr during the dark phase showed NTS astrocyte activation, reflected in an increase in the number (65%) and morphological complexity of glial‐fibrillary acidic protein (GFAP)‐immunoreactive cells adjacent to the area postrema (AP), compared to control chow fed mice. To measure the impact of astrocyte activation on food intake, we delivered designer receptors exclusively activated by designer drugs (DREADDs) to DVC astrocytes (encompassing NTS, AP, and dorsal motor nucleus of the vagus) using an adeno‐associated viral (AAV) vector (AAV‐GFAP‐hM3Dq_mCherry). Chemogenetic activation with clozapine‐N‐oxide (0.3 mg/kg) produced in greater morphological complexity in astrocytes and reduced dark‐phase feeding by 84% at 4 hr postinjection compared with vehicle treatment. hM3Dq‐activation of DVC astrocytes also reduced refeeding after an overnight fast (71% lower, 4 hr postinjection) when compared to AAV‐GFAP‐mCherry expressing control mice. DREADD‐mediated astrocyte activation did not impact locomotion. hM3Dq activation of DVC astrocytes induced c‐FOS in neighboring neuronal feeding circuits (including in the parabrachial nucleus). This indicates that NTS astrocytes respond to acute nutritional excess, are involved in the integration of peripheral satiety signals, and can reduce food intake when activated.
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Affiliation(s)
- Alastair J MacDonald
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, UK.,School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, UK
| | - Fiona E Holmes
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, UK
| | - Craig Beall
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Anthony E Pickering
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, UK.,Anaesthesia, Pain and Critical Care Sciences, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Kate L J Ellacott
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, UK
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