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Barahona MJ, Ferrada L, Vera M, Nualart F. Tanycytes release glucose using the glucose-6-phosphatase system during hypoglycemia to control hypothalamic energy balance. Mol Metab 2024; 84:101940. [PMID: 38641253 PMCID: PMC11060961 DOI: 10.1016/j.molmet.2024.101940] [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: 01/10/2024] [Revised: 04/09/2024] [Accepted: 04/09/2024] [Indexed: 04/21/2024] Open
Abstract
OBJECTIVE The liver releases glucose into the blood using the glucose-6-phosphatase (G6Pase) system, a multiprotein complex located in the endoplasmic reticulum (ER). Here, we show for the first time that the G6Pase system is also expressed in hypothalamic tanycytes, and it is required to regulate energy balance. METHODS Using automatized qRT-PCR and immunohistochemical analyses, we evaluated the expression of the G6Pase system. Fluorescent glucose analogue (2-NBDG) uptake was evaluated by 4D live-cell microscopy. Glucose release was tested using a glucose detection kit and high-content live-cell analysis instrument, Incucyte s3. In vivo G6pt knockdown in tanycytes was performed by AAV1-shG6PT-mCherry intracerebroventricular injection. Body weight gain, adipose tissue weight, food intake, glucose metabolism, c-Fos, and neuropeptide expression were evaluated at 4 weeks post-transduction. RESULTS Tanycytes sequester glucose-6-phosphate (G6P) into the ER through the G6Pase system and release glucose in hypoglycaemia via facilitative glucose transporters (GLUTs). Strikingly, in vivo tanycytic G6pt knockdown has a powerful peripheral anabolic effect observed through decreased body weight, white adipose tissue (WAT) tissue mass, and strong downregulation of lipogenesis genes. Selective deletion of G6pt in tanycytes also decreases food intake, c-Fos expression in the arcuate nucleus (ARC), and Npy mRNA expression in fasted mice. CONCLUSIONS The tanycyte-associated G6Pase system is a central mechanism involved in controlling metabolism and energy balance.
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Affiliation(s)
- María José Barahona
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile; Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile; Laboratory of Appetite Physiology (FIDELA), Faculty of Medicine and Sciences, University San Sebastián, Concepción Campus, Concepción, Chile
| | - Luciano Ferrada
- Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile
| | - Matías Vera
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile; Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile
| | - Francisco Nualart
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile; Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile.
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2
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Saldivia N, Salazar K, Cifuentes M, Espinoza F, Harrison FE, Nualart F. Ascorbic acid and its transporter SVCT2, affect radial glia cells differentiation in postnatal stages. Glia 2024; 72:708-727. [PMID: 38180226 DOI: 10.1002/glia.24498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 12/03/2023] [Accepted: 12/10/2023] [Indexed: 01/06/2024]
Abstract
Radial glia (RG) cells generate neurons and glial cells that make up the cerebral cortex. Both in rodents and humans, these stem cells remain for a specific time after birth, named late radial glia (lRG). The knowledge of lRG and molecules that may be involved in their differentiation is based on very limited data. We analyzed whether ascorbic acid (AA) and its transporter SVCT2, are involved in lRG cells differentiation. We demonstrated that lRG cells are highly present between the first and fourth postnatal days. Anatomical characterization of lRG cells, revealed that lRG cells maintained their bipolar morphology and stem-like character. When lRG cells were labeled with adenovirus-eGFP at 1 postnatal day, we detected that some cells display an obvious migratory neuronal phenotype, suggesting that lRG cells continue generating neurons postnatally. Moreover, we demonstrated that SVCT2 was apically polarized in lRG cells. In vitro studies using the transgenic mice SVCT2+/- and SVCT2tg (SVCT2-overexpressing mouse), showed that decreased SVCT2 levels led to accelerated differentiation into astrocytes, whereas both AA treatment and elevated SVCT2 expression maintain the lRG cells in an undifferentiated state. In vivo overexpression of SVCT2 in lRG cells generated cells with a rounded morphology that were migratory and positive for proliferation and neuronal markers. We also examined mediators that can be involved in AA/SVCT2-modulated signaling pathways, determining that GSK3-β through AKT, mTORC2, and PDK1 is active in brains with high levels of SVCT2/AA. Our data provide new insights into the role of AA and SVCT2 in late RG cells.
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Affiliation(s)
- Natalia Saldivia
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy, CMA BIO BIO, Faculty of Biological Sciences, Universidad de Concepción, Concepción, Chile
| | - Katterine Salazar
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy, CMA BIO BIO, Faculty of Biological Sciences, Universidad de Concepción, Concepción, Chile
| | - Manuel Cifuentes
- Department of Cell Biology, Genetics and Physiology, Universidad de Málaga, IBIMA, Málaga, Spain
| | - Francisca Espinoza
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy, CMA BIO BIO, Faculty of Biological Sciences, Universidad de Concepción, Concepción, Chile
| | - Fiona E Harrison
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, USA
| | - Francisco Nualart
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy, CMA BIO BIO, Faculty of Biological Sciences, Universidad de Concepción, Concepción, Chile
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3
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Chambers ME, Nuibe EH, Reno-Bernstein CM. Brain Regulation of Cardiac Function during Hypoglycemia. Metabolites 2023; 13:1089. [PMID: 37887414 PMCID: PMC10608630 DOI: 10.3390/metabo13101089] [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: 08/29/2023] [Revised: 10/02/2023] [Accepted: 10/16/2023] [Indexed: 10/28/2023] Open
Abstract
Hypoglycemia occurs frequently in people with type 1 and type 2 diabetes. Hypoglycemia activates the counter-regulatory response. Besides peripheral glucose sensors located in the pancreas, mouth, gastrointestinal tract, portal vein, and carotid body, many brain regions also contain glucose-sensing neurons that detect this fall in glucose. The autonomic nervous system innervates the heart, and during hypoglycemia, can cause many changes. Clinical and animal studies have revealed changes in electrocardiograms during hypoglycemia. Cardiac repolarization defects (QTc prolongation) occur during moderate levels of hypoglycemia. When hypoglycemia is severe, it can be fatal. Cardiac arrhythmias are thought to be the major mediator of sudden death due to severe hypoglycemia. Both the sympathetic and parasympathetic nervous systems of the brain have been implicated in regulating these arrhythmias. Besides cardiac arrhythmias, hypoglycemia can have profound changes in the heart and most of these changes are exacerbated in the setting of diabetes. A better understanding of how the brain regulates cardiac changes during hypoglycemia will allow for better therapeutic intervention to prevent cardiovascular death associated with hypoglycemia in people with diabetes. The aim of this paper is to provide a narrative review of what is known in the field regarding how the brain regulates the heart during hypoglycemia.
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Affiliation(s)
| | | | - Candace M. Reno-Bernstein
- Division of Endocrinology, Metabolism, and Diabetes, University of Utah School of Medicine, Salt Lake City, UT 84112, USA (E.H.N.)
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4
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Nualart F, Cifuentes M, Ramírez E, Martínez F, Barahona MJ, Ferrada L, Saldivia N, Bongarzone ER, Thorens B, Salazar K. Hyperglycemia increases SCO-spondin and Wnt5a secretion into the cerebrospinal fluid to regulate ependymal cell beating and glucose sensing. PLoS Biol 2023; 21:e3002308. [PMID: 37733692 PMCID: PMC10513282 DOI: 10.1371/journal.pbio.3002308] [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: 02/02/2023] [Accepted: 08/22/2023] [Indexed: 09/23/2023] Open
Abstract
Hyperglycemia increases glucose concentrations in the cerebrospinal fluid (CSF), activating glucose-sensing mechanisms and feeding behavior in the hypothalamus. Here, we discuss how hyperglycemia temporarily modifies ependymal cell ciliary beating to increase hypothalamic glucose sensing. A high level of glucose in the rat CSF stimulates glucose transporter 2 (GLUT2)-positive subcommissural organ (SCO) cells to release SCO-spondin into the dorsal third ventricle. Genetic inactivation of mice GLUT2 decreases hyperglycemia-induced SCO-spondin secretion. In addition, SCO cells secrete Wnt5a-positive vesicles; thus, Wnt5a and SCO-spondin are found at the apex of dorsal ependymal cilia to regulate ciliary beating. Frizzled-2 and ROR2 receptors, as well as specific proteoglycans, such as glypican/testican (essential for the interaction of Wnt5a with its receptors) and Cx43 coupling, were also analyzed in ependymal cells. Finally, we propose that the SCO-spondin/Wnt5a/Frizzled-2/Cx43 axis in ependymal cells regulates ciliary beating, a cyclic and adaptive signaling mechanism to control glucose sensing.
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Affiliation(s)
- Francisco Nualart
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
- Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile
| | - Manuel Cifuentes
- Department of Cell Biology, Genetics and Physiology, University of Malaga, Málaga Biomedical Research Institute and Nanomedicine Platform (IBIMA-BIONAND Platform), Malaga, Spain
| | - Eder Ramírez
- Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile
| | - Fernando Martínez
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
| | - María José Barahona
- Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile
| | - Luciano Ferrada
- Center for Advanced Microscopy CMA BIO BIO, University of Concepcion, Concepcion, Chile
| | - Natalia Saldivia
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
| | - Ernesto R. Bongarzone
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Bernard Thorens
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Katterine Salazar
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
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5
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Schwartz MW, Krinsley JS, Faber CL, Hirsch IB, Brownlee M. Brain Glucose Sensing and the Problem of Relative Hypoglycemia. Diabetes Care 2023; 46:237-244. [PMID: 36701597 PMCID: PMC9887623 DOI: 10.2337/dc22-1445] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 11/22/2022] [Indexed: 01/27/2023]
Abstract
"Relative hypoglycemia" is an often-overlooked complication of diabetes characterized by an increase in the glycemic threshold for detecting and responding to hypoglycemia. The clinical relevance of this problem is linked to growing evidence that among patients with critical illness, higher blood glucose in the intensive care unit is associated with higher mortality among patients without diabetes but lower mortality in patients with preexisting diabetes and an elevated prehospitalization HbA1c. Although additional studies are needed, the cardiovascular stress associated with hypoglycemia perception, which can occur at normal or even elevated glucose levels in patients with diabetes, offers a plausible explanation for this difference in outcomes. Little is known, however, regarding how hypoglycemia is normally detected by the brain, much less how relative hypoglycemia develops in patients with diabetes. In this article, we explore the role in hypoglycemia detection played by glucose-responsive sensory neurons supplying peripheral vascular beds and/or circumventricular organs. These observations support a model wherein relative hypoglycemia results from diabetes-associated impairment of this neuronal glucose-sensing process. By raising the glycemic threshold for hypoglycemia perception, this impairment may contribute to the increased mortality risk associated with standard glycemic management of critically ill patients with diabetes.
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Affiliation(s)
- Michael W. Schwartz
- Department of Medicine, University of Washington Medicine Diabetes Institute, Seattle, WA
| | - James S. Krinsley
- Stamford Hospital, Stamford, CT
- Columbia Vagelos College of Physicians and Surgeons, New York, NY
| | - Chelsea L. Faber
- Ivy Brain Tumor Center, Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AZ
| | - Irl B. Hirsch
- Department of Medicine, University of Washington Medicine Diabetes Institute, Seattle, WA
| | - Michael Brownlee
- Einstein Diabetes Research Center, Albert Einstein College of Medicine, Bronx, NY
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6
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Jensen VFH, Schefe LH, Jacobsen H, Mølck AM, Almholt K, Sjögren I, Dalsgaard CM, Kirk RK, Benie AJ, Petersen BO, Kyhn MS, Overgaard AJ, Bjørnsdottir I, Stannard DR, Offenberg HK, Egecioglu E. Normal Neurodevelopment and Fertility in Juvenile Male Rats Exposed to Polyethylene Glycol Following Dosing With PEGylated rFIX (Nonacog Beta Pegol, N9-GP): Evidence from a 10-Week Repeat-Dose Toxicity Study. Int J Toxicol 2022; 41:455-475. [DOI: 10.1177/10915818221121054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
N9-GP/Rebinyn®/Refixia® is an approved PEGylated (polyethylene glycol-conjugated) recombinant human factor IX intended for prophylactic and/or on-demand treatment in adults and children with haemophilia B. A juvenile neurotoxicity study was conducted in male rats to evaluate effects on neurodevelopment, sexual maturation, and fertility following repeat-dosing of N9-GP. Male rats were dosed twice weekly from Day 21 of age with N9-GP or vehicle for 10 weeks, followed by a dosing-free recovery period for 13 weeks and terminated throughout the dosing and recovery periods. Overall, dosing N9-GP to juvenile rats did not result in any functional or pathological effects, as measured by neurobehavioural/neurocognitive tests, including motor activity, sensory function, learning and memory as well as growth, sexual maturation, and fertility. This was further supported by the extensive histopathologic evaluation of brain tissue. Exposure and distribution of polyethylene glycol was investigated in plasma, choroid plexus, cerebrospinal fluid, and brain sections. PEG did not cross the blood brain barrier and PEG exposure did not result in any effects on neurodevelopment. In conclusion, dosing of N9-GP to juvenile rats did not identify any effects on growth, sexual maturation and fertility, clinical and histological pathology, or neurodevelopment related to PEG exposure and supports the prophylactic use of N9-GP in children.
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Affiliation(s)
- Vivi F. H. Jensen
- Department of Safety Sciences & Imaging, Novo Nordisk A/S, Måløv, Denmark
| | - Line H. Schefe
- Department of DMPK (Drug Metabolism and Pharmacokinetics) and Non-clinical Project Management, Novo Nordisk A/S, Måløv, Denmark
| | - Helene Jacobsen
- Department of DMPK (Drug Metabolism and Pharmacokinetics) and Non-clinical Project Management, Novo Nordisk A/S, Måløv, Denmark
| | - Anne-Marie Mølck
- Department of Safety Sciences & Imaging, Novo Nordisk A/S, Måløv, Denmark
| | - Kasper Almholt
- Department of Safety Sciences & Imaging, Novo Nordisk A/S, Måløv, Denmark
| | - Ingrid Sjögren
- Department of Safety Sciences & Imaging, Novo Nordisk A/S, Måløv, Denmark
| | | | - Rikke K Kirk
- Department of Safety Sciences & Imaging, Novo Nordisk A/S, Måløv, Denmark
| | - Andrew J. Benie
- Department of Biophysics & Formulation 1, Novo Nordisk A/S, Måløv, Denmark
| | - Bent O. Petersen
- Department of Biophysics & Formulation 1, Novo Nordisk A/S, Måløv, Denmark
| | - Mette S. Kyhn
- Department of Non-clinical and Clinical Assay Sciences, Novo Nordisk A/S, Måløv, Denmark
| | - Anne J. Overgaard
- Department of Non-clinical and Clinical Assay Sciences, Novo Nordisk A/S, Måløv, Denmark
| | - Inga Bjørnsdottir
- Department of DMPK (Drug Metabolism and Pharmacokinetics) and Non-clinical Project Management, Novo Nordisk A/S, Måløv, Denmark
| | | | - Hanne K. Offenberg
- Department of DMPK (Drug Metabolism and Pharmacokinetics) and Non-clinical Project Management, Novo Nordisk A/S, Måløv, Denmark
| | - Emil Egecioglu
- Department of DMPK (Drug Metabolism and Pharmacokinetics) and Non-clinical Project Management, Novo Nordisk A/S, Måløv, Denmark
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7
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Imbernon M, Dehouck B, Prevot V. Glycemic control: Tanycytes march to the beat of the suprachiasmatic drummer. Curr Biol 2022; 32:R173-R176. [DOI: 10.1016/j.cub.2022.01.038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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8
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Chen ZH, Li S, Xu M, Liu CC, Ye H, Wang B, Wu QF. Single-cell Transcriptomic Profiling of the Hypothalamic Median Eminence during Aging. J Genet Genomics 2022; 49:523-536. [PMID: 35032691 DOI: 10.1016/j.jgg.2022.01.001] [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: 10/04/2021] [Revised: 12/31/2021] [Accepted: 01/03/2022] [Indexed: 10/19/2022]
Abstract
Aging is a slow and progressive natural process that compromises the normal functions of cells, tissues, organs and systems. The aging of the hypothalamic median eminence (ME), a structural gate linking neural and endocrine systems, may impair hormone release, energy homeostasis and central sensing of circulating molecules, leading to systemic and reproductive aging. However, the molecular and cellular features of ME aging remain largely unknown. Here we describe the transcriptional landscape of young and middle-aged mouse ME at single-cell resolution, revealing the common and cell-type-specific transcriptional changes with age. The transcriptional changes in cell-intrinsic programs, cell-cell crosstalk and cell-extrinsic factors highlight five molecular features of ME aging and also implicate several potentially druggable targets at cellular, signaling and molecular levels. Importantly, our results suggest that vascular and leptomeningeal cells (VLMCs) may lead the asynchronized aging process among diverse cell types and drive local inflammation and cellular senescence via a unique secretome. Together, our study uncovers how intrinsic and extrinsic features of each cell type in the hypothalamic ME are changed by the aging process, which will facilitate our understanding of brain aging and provide clues for efficient anti-aging intervention at the middle-aged stage.
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Affiliation(s)
- Zhen-Hua Chen
- State Key Laboratory of Molecular Development Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100101, China
| | - Si Li
- State Key Laboratory of Molecular Development Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100101, China
| | - Mingrui Xu
- State Key Laboratory of Molecular Development Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100101, China
| | - Candace C Liu
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Hongying Ye
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Ben Wang
- Department of Obstetrics and Gynecology, Baoding Second Central Hospital, Baoding, Hebei 072750, China
| | - Qing-Feng Wu
- State Key Laboratory of Molecular Development Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100101, China; Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Beijing 100101, China; Chinese Institute for Brain Research, Beijing 102206, China; Beijing Children's Hospital, Capital Medical University, Beijing 100045, China.
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9
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Rodríguez-Cortés B, Hurtado-Alvarado G, Martínez-Gómez R, León-Mercado LA, Prager-Khoutorsky M, Buijs RM. Suprachiasmatic nucleus-mediated glucose entry into the arcuate nucleus determines the daily rhythm in blood glycemia. Curr Biol 2022; 32:796-805.e4. [PMID: 35030330 DOI: 10.1016/j.cub.2021.12.039] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/19/2021] [Accepted: 12/16/2021] [Indexed: 12/20/2022]
Abstract
Glycemia is maintained within very narrow boundaries with less than 5% variation at a given time of the day. However, over the circadian cycle, glycemia changes with almost 50% difference. How the suprachiasmatic nucleus, the biological clock, maintains these day-night variations with such tiny disparities remains obscure. We show that via vasopressin release at the beginning of the sleep phase, the suprachiasmatic nucleus increases the glucose transporter GLUT1 in tanycytes. Hereby GLUT1 promotes glucose entrance into the arcuate nucleus, thereby lowering peripheral glycemia. Conversely, blocking vasopressin activity or the GLUT1 transporter at the daily trough of glycemia increases circulating glucose levels usually seen at the peak of the rhythm. Thus, biological clock-controlled mechanisms promoting glucose entry into the arcuate nucleus explain why peripheral blood glucose is low before sleep onset.
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Affiliation(s)
- Betty Rodríguez-Cortés
- Department of Cellular Biology and Physiology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mario de la Cueva Circuit, Mexico City 04510, Mexico
| | - Gabriela Hurtado-Alvarado
- Department of Cellular Biology and Physiology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mario de la Cueva Circuit, Mexico City 04510, Mexico
| | - Ricardo Martínez-Gómez
- Department of Cellular Biology and Physiology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mario de la Cueva Circuit, Mexico City 04510, Mexico
| | - Luis A León-Mercado
- Department of Internal Medicine, Center for Hypothalamic Research, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Masha Prager-Khoutorsky
- Department of Physiology, McIntyre Medical Sciences Building, McGill University, 3655 Promenade Sir-William-Osler, Montréal, QC H3G 1Y6, Canada
| | - Ruud M Buijs
- Department of Cellular Biology and Physiology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mario de la Cueva Circuit, Mexico City 04510, Mexico.
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10
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Clayton RW, Lovell-Badge R, Galichet C. The Properties and Functions of Glial Cell Types of the Hypothalamic Median Eminence. Front Endocrinol (Lausanne) 2022; 13:953995. [PMID: 35966104 PMCID: PMC9363565 DOI: 10.3389/fendo.2022.953995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 06/17/2022] [Indexed: 02/06/2023] Open
Abstract
The median eminence (ME) is part of the neuroendocrine system (NES) that functions as a crucial interface between the hypothalamus and pituitary gland. The ME contains many non-neuronal cell types, including oligodendrocytes, oligodendrocyte precursor cells (OPCs), tanycytes, astrocytes, pericytes, microglia and other immune cells, which may be involved in the regulation of NES function. For example, in mice, ablation of tanycytes (a special class of ependymal glia with stem cell-like functions) results in weight gain, feeding, insulin insensitivity and increased visceral adipose, consistent with the demonstrated ability of these cells to sense and transport both glucose and leptin, and to differentiate into neurons that control feeding and metabolism in the hypothalamus. To give a further example, OPCs in the ME of mice have been shown to rapidly respond to dietary signals, in turn controlling composition of the extracellular matrix in the ME, derived from oligodendrocyte-lineage cells, which may contribute to the previously described role of these cells in actively maintaining leptin-receptor-expressing dendrites in the ME. In this review, we explore and discuss recent advances such as these, that have developed our understanding of how the various cell types of the ME contribute to its function in the NES as the interface between the hypothalamus and pituitary gland. We also highlight avenues of future research which promise to uncover additional functions of the ME and the glia, stem and progenitor cells it contains.
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11
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Baeza V, Cifuentes M, Martínez F, Ramírez E, Nualart F, Ferrada L, Oviedo MJ, De Lima I, Troncoso N, Saldivia N, Salazar K. IIIG9 inhibition in adult ependymal cells changes adherens junctions structure and induces cellular detachment. Sci Rep 2021; 11:18537. [PMID: 34535732 PMCID: PMC8448829 DOI: 10.1038/s41598-021-97948-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 08/27/2021] [Indexed: 11/30/2022] Open
Abstract
Ependymal cells have multiple apical cilia that line the ventricular surfaces and the central canal of spinal cord. In cancer, the loss of ependymal cell polarity promotes the formation of different types of tumors, such as supratentorial anaplastic ependymomas, which are highly aggressive in children. IIIG9 (PPP1R32) is a protein restricted to adult ependymal cells located in cilia and in the apical cytoplasm and has unknown function. In this work, we studied the expression and localization of IIIG9 in the adherens junctions (cadherin/β-catenin-positive junctions) of adult brain ependymal cells using confocal and transmission electron microscopy. Through in vivo loss-of-function studies, ependymal denudation (single-dose injection experiments of inhibitory adenovirus) was observed, inducing the formation of ependymal cells with a "balloon-like" morphology. These cells had reduced cadherin expression (and/or delocalization) and cleavage of the cell death marker caspase-3, with "cilia rigidity" morphology (probably vibrational beating activity) and ventriculomegaly occurring prior to these events. Finally, after performing continuous infusions of adenovirus for 14 days, we observed total cell denudation and reactive parenchymal astrogliosis. Our data confirmed that IIIG9 is essential for the maintenance of adherens junctions of polarized ependymal cells. Eventually, altered levels of this protein in ependymal cell differentiation may increase ventricular pathologies, such as hydrocephalus or neoplastic transformation.
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Affiliation(s)
- Victor Baeza
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, 4030000, Concepcion, Chile
| | - Manuel Cifuentes
- Department of Cell Biology, Genetics and Physiology, University of Malaga, IBIMA, Malaga, Spain
- Andalusian Center for Nanomedicine and Biotechnology, BIONAND, Malaga, Spain
- Networking Research Center on Bioengineering, Biomaterials and Nanomedicine, Malaga, Spain
| | - Fernando Martínez
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, 4030000, Concepcion, Chile
| | - Eder Ramírez
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, 4030000, Concepcion, Chile
| | - Francisco Nualart
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, 4030000, Concepcion, Chile
- Faculty of Biological Sciences, Center for Advanced Microscopy CMA BIOBIO, University of Concepcion, Concepcion, Chile
| | - Luciano Ferrada
- Faculty of Biological Sciences, Center for Advanced Microscopy CMA BIOBIO, University of Concepcion, Concepcion, Chile
| | - María José Oviedo
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, 4030000, Concepcion, Chile
| | - Isabelle De Lima
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, 4030000, Concepcion, Chile
| | - Ninoschka Troncoso
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, 4030000, Concepcion, Chile
| | - Natalia Saldivia
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, 4030000, Concepcion, Chile
| | - Katterine Salazar
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, 4030000, Concepcion, Chile.
- Faculty of Biological Sciences, Center for Advanced Microscopy CMA BIOBIO, University of Concepcion, Concepcion, Chile.
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12
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Lhomme T, Clasadonte J, Imbernon M, Fernandois D, Sauve F, Caron E, Lima N, Heras V, Martinez-Corral I, Müller-Fielitz H, Rasika S, Schwaninger M, Nogueiras R, Prevot V. Tanycytic networks mediate energy balance by feeding lactate to glucose-insensitive POMC neurons. J Clin Invest 2021; 131:e140521. [PMID: 34324439 DOI: 10.1172/jci140521] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/28/2021] [Indexed: 11/17/2022] Open
Abstract
Hypothalamic glucose sensing enables an organism to match energy expenditure and food intake to circulating levels of glucose, the main energy source of the brain. Here, we established that tanycytes of the hypothalamic arcuate nucleus, specialized glia that line the wall of the third ventricle, convert brain glucose supplies into lactate that they transmit through monocarboxylate transporters to arcuate proopiomelanocortin neurons, which integrate this signal to drive their activity and to adapt the metabolic response to meet physiological demands. Furthermore, this transmission required the formation of extensive Connexin-43 gap-junction-mediated metabolic networks by arcuate tanycytes. Selectively suppressing either tanycytic monocarboxylate transporters or gap junctions resulted in altered feeding behavior and energy metabolism. Tanycytic intercellular communication and lactate production are thus integral to the mechanism by which hypothalamic neurons that regulate energy and glucose homeostasis efficiently perceive alterations in systemic glucose levels as a function of the physiological state of the organism.
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Affiliation(s)
- Tori Lhomme
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, INSERM U1172, Lille, France
| | - Jerome Clasadonte
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, INSERM U1172, Lille, France
| | - Monica Imbernon
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, INSERM U1172, Lille, France
| | - Daniela Fernandois
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, INSERM U1172, Lille, France
| | - Florent Sauve
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, INSERM U1172, Lille, France
| | - Emilie Caron
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, INSERM U1172, Lille, France
| | - Natalia Lima
- CIMUS, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Violeta Heras
- CIMUS, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Ines Martinez-Corral
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, INSERM U1172, Lille, France
| | - Helge Müller-Fielitz
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany
| | - S Rasika
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, INSERM U1172, Lille, France
| | - Markus Schwaninger
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany
| | - Ruben Nogueiras
- CIMUS, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Vincent Prevot
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, INSERM U1172, Lille, France
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13
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Echeverría C, Nualart F, Ferrada L, Smith GJ, Godoy AS. Hexose Transporters in Cancer: From Multifunctionality to Diagnosis and Therapy. Trends Endocrinol Metab 2021; 32:198-211. [PMID: 33518451 DOI: 10.1016/j.tem.2020.12.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 12/21/2020] [Accepted: 12/23/2020] [Indexed: 12/21/2022]
Abstract
Cancer cells increase their metabolic activity by enhancing glucose uptake through overexpression of hexose transporters (Gluts). Gluts also have the capacity to transport other molecules besides glucose, including fructose, mannose, and dehydroascorbic acid (DHA), the oxidized form of vitamin C. The majority of research studies in this field have focused on the role of glucose transport and metabolism in cancer, leaving a substantial gap in our knowledge of the contribution of other hexoses and DHA in cancer biology. Here, we summarize the most recent advances in understanding the role that the multifunctional transport capacity of Gluts plays in biological and clinical aspects of cancer, and how these characteristics can be exploited in the search for novel diagnostic and therapeutic strategies.
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Affiliation(s)
- Carolina Echeverría
- Centro de Biología Celular y Biomedicina, Universidad San Sebastián, Santiago, Chile; Centro de Investigación e Innovación Biomédica, Universidad de los Andes, Santiago, Chile
| | - Francisco Nualart
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile; Centro de Microscopía Avanzada, Universidad de Concepción, Concepción, Chile
| | - Luciano Ferrada
- Centro de Microscopía Avanzada, Universidad de Concepción, Concepción, Chile
| | - Gary J Smith
- Department of Urology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Alejandro S Godoy
- Centro de Biología Celular y Biomedicina, Universidad San Sebastián, Santiago, Chile; Department of Urology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA.
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14
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Yoo S, Cha D, Kim S, Jiang L, Cooke P, Adebesin M, Wolfe A, Riddle R, Aja S, Blackshaw S. Tanycyte ablation in the arcuate nucleus and median eminence increases obesity susceptibility by increasing body fat content in male mice. Glia 2020; 68:1987-2000. [PMID: 32173924 PMCID: PMC7423758 DOI: 10.1002/glia.23817] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 02/28/2020] [Accepted: 02/28/2020] [Indexed: 12/11/2022]
Abstract
Tanycytes are radial glial cells located in the mediobasal hypothalamus. Recent studies have proposed that tanycytes play an important role in hypothalamic control of energy homeostasis, although this has not been directly tested. Here, we report the phenotype of mice in which tanycytes of the arcuate nucleus and median eminence were conditionally ablated in adult mice. Although the cerebrospinal fluid-hypothalamic barrier was rendered more permeable following tanycyte ablation, neither the blood-hypothalamic barrier nor leptin-induced pSTAT3 activation in hypothalamic parenchyma were affected. We observed a significant increase in visceral fat distribution accompanying insulin insensitivity in male mice, without significant effect on either body weight or food intake. A high-fat diet tended to accelerate overall body weight gain in tanycyte-ablated mice, but the development of visceral adiposity and insulin insensitivity was comparable to wildtype. Thermoneutral housing exacerbated fat accumulation and produced a shift away from fat oxidation in tanycyte-ablated mice. These results clarify the extent to which tanycytes regulate energy balance, and demonstrate a role for tanycytes in regulating fat metabolism.
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Affiliation(s)
- Sooyeon Yoo
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - David Cha
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Soohyun Kim
- Department of Orthopedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Lizhi Jiang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Patrick Cooke
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mobolanie Adebesin
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Andrew Wolfe
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ryan Riddle
- Department of Orthopedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Baltimore Veterans Administration Medical Center, Baltimore, Maryland
| | - Susan Aja
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Center for Human Systems Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
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15
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Glucose transporters in brain in health and disease. Pflugers Arch 2020; 472:1299-1343. [PMID: 32789766 PMCID: PMC7462931 DOI: 10.1007/s00424-020-02441-x] [Citation(s) in RCA: 216] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/20/2020] [Accepted: 07/24/2020] [Indexed: 12/15/2022]
Abstract
Energy demand of neurons in brain that is covered by glucose supply from the blood is ensured by glucose transporters in capillaries and brain cells. In brain, the facilitative diffusion glucose transporters GLUT1-6 and GLUT8, and the Na+-d-glucose cotransporters SGLT1 are expressed. The glucose transporters mediate uptake of d-glucose across the blood-brain barrier and delivery of d-glucose to astrocytes and neurons. They are critically involved in regulatory adaptations to varying energy demands in response to differing neuronal activities and glucose supply. In this review, a comprehensive overview about verified and proposed roles of cerebral glucose transporters during health and diseases is presented. Our current knowledge is mainly based on experiments performed in rodents. First, the functional properties of human glucose transporters expressed in brain and their cerebral locations are described. Thereafter, proposed physiological functions of GLUT1, GLUT2, GLUT3, GLUT4, and SGLT1 for energy supply to neurons, glucose sensing, central regulation of glucohomeostasis, and feeding behavior are compiled, and their roles in learning and memory formation are discussed. In addition, diseases are described in which functional changes of cerebral glucose transporters are relevant. These are GLUT1 deficiency syndrome (GLUT1-SD), diabetes mellitus, Alzheimer’s disease (AD), stroke, and traumatic brain injury (TBI). GLUT1-SD is caused by defect mutations in GLUT1. Diabetes and AD are associated with changed expression of glucose transporters in brain, and transporter-related energy deficiency of neurons may contribute to pathogenesis of AD. Stroke and TBI are associated with changes of glucose transporter expression that influence clinical outcome.
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16
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MCH Neurons Regulate Permeability of the Median Eminence Barrier. Neuron 2020; 107:306-319.e9. [PMID: 32407670 PMCID: PMC7383232 DOI: 10.1016/j.neuron.2020.04.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 03/06/2020] [Accepted: 04/20/2020] [Indexed: 01/17/2023]
Abstract
Melanin-concentrating hormone (MCH)-expressing neurons are key regulators of energy and glucose homeostasis. Here, we demonstrate that they provide dense projections to the median eminence (ME) in close proximity to tanycytes and fenestrated vessels. Chemogenetic activation of MCH neurons as well as optogenetic stimulation of their projections in the ME enhance permeability of the ME by increasing fenestrated vascular loops and enhance leptin action in the arcuate nucleus of the hypothalamus (ARC). Unbiased phosphoRiboTrap-based assessment of cell activation upon chemogenetic MCH neuron activation reveals MCH-neuron-dependent regulation of endothelial cells. MCH neurons express the vascular endothelial growth factor A (VEGFA), and blocking VEGF-R signaling attenuates the leptin-sensitizing effect of MCH neuron activation. Our experiments reveal that MCH neurons directly regulate permeability of the ME barrier, linking the activity of energy state and sleep regulatory neurons to the regulation of hormone accessibility to the ARC. MCH neurons provide dense projections to the median eminence MCH neuron activation promotes permeability of the median eminence barrier MCH neuron activation enhances microvessel fenestration in the ME MCH neuron activation enhances leptin action in the arcuate nucleus
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17
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Dautta M, Alshetaiwi M, Escobar J, Tseng P. Passive and wireless, implantable glucose sensing with phenylboronic acid hydrogel-interlayer RF resonators. Biosens Bioelectron 2020; 151:112004. [PMID: 31999570 DOI: 10.1016/j.bios.2020.112004] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/28/2019] [Accepted: 01/02/2020] [Indexed: 02/04/2023]
Abstract
A phenylboronic acid-based, hydrogel-interlayer Radio-Frequency (RF) resonator is demonstrated as a highly-responsive, passive and wireless sensor for glucose monitoring. Constructs are composed of unanchored, capacitively-coupled split rings interceded by glucose-responsive hydrogels. Phenylboronic acid-hydrogels exhibit volumetric and dielectric variations in response to environmental glucose concentrations-these are efficiently converted to large shifts in the resonant response of interlayer-RF sensors. These tiny, stretchable and scalable sensors (5 mm × 5 mm x 250 μm) require no microelectronics or power at the sensing node and can be read-out remotely via near-field coupling. Sensors exhibit high sensitivities (~10% shift in resonant frequency-corresponding to 50 MHz-per 150 mg/dL of glucose), possess a limit of detection of 10 mg/dL, and a step response time of approximately 1 h to abrupt shifts in carbohydrate concentration. Notably, these sensors exhibited no signal drift or hysteresis over the time periods characterized herein (45 days at room temperature). We transform sensors into bioelectronic RF reporter-tags via the attachment of a single LED-these remotely report on glucose concentration via emitted light. We anticipate the non-degradative, long-term nature of both RF read-out and phenylboronic acid-based hydrogels will enable biosensors capable of long-term, remote read-out of glucose.
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Affiliation(s)
- Manik Dautta
- Department of Electrical Engineering and Computer Science, University of California Irvine, Engineering Hall #3110, Irvine, CA, 92697, USA
| | - Muhannad Alshetaiwi
- Department of Electrical Engineering and Computer Science, University of California Irvine, Engineering Hall #3110, Irvine, CA, 92697, USA
| | - Jens Escobar
- Department of Biomedical Engineering, University of California Irvine, Engineering Hall #3110, Irvine, CA, 92697, USA
| | - Peter Tseng
- Department of Electrical Engineering and Computer Science, University of California Irvine, Engineering Hall #3110, Irvine, CA, 92697, USA; Department of Biomedical Engineering, University of California Irvine, Engineering Hall #3110, Irvine, CA, 92697, USA.
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18
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Müller-Fielitz H, Schwaninger M. The Role of Tanycytes in the Hypothalamus-Pituitary-Thyroid Axis and
the Possibilities for Their Genetic Manipulation. Exp Clin Endocrinol Diabetes 2019; 128:388-394. [DOI: 10.1055/a-1065-1855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
AbstractThyroid hormone (TH) regulation is important for development, energy homeostasis,
heart function, and bone formation. To control the effects of TH in target
organs, the hypothalamus-pituitary-thyroid (HPT) axis and the tissue-specific
availability of TH are highly regulated by negative feedback. To exert a central
feedback, TH must enter the brain via specific transport mechanisms and cross
the blood-brain barrier. Here, tanycytes, which are located in the ventral walls
of the 3rd ventricle in the mediobasal hypothalamus (MBH), function as
gatekeepers. Tanycytes are able to transport, sense, and modify the release of
hormones of the HPT axis and are involved in feedback regulation. In this
review, we focus on the relevance of tanycytes in thyrotropin-releasing hormone
(TRH) release and review available genetic tools to investigate the
physiological functions of these cells.
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Affiliation(s)
- Helge Müller-Fielitz
- Institute for Experimental and Clinical Pharmacology and Toxicology,
Lübeck, University of Lübeck, Germany
| | - Markus Schwaninger
- Institute for Experimental and Clinical Pharmacology and Toxicology,
Lübeck, University of Lübeck, Germany
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