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Salgado M, Ordenes P, Villagra M, Uribe E, García-Robles MDLA, Tarifeño-Saldivia E. When a Little Bit More Makes the Difference: Expression Levels of GKRP Determines the Subcellular Localization of GK in Tanycytes. Front Neurosci 2019; 13:275. [PMID: 30983961 PMCID: PMC6449865 DOI: 10.3389/fnins.2019.00275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 03/08/2019] [Indexed: 01/01/2023] Open
Abstract
Glucose homeostasis is performed by specialized cells types that detect and respond to changes in systemic glucose concentration. Hepatocytes, β-cells and hypothalamic tanycytes are part of the glucosensor cell types, which express several proteins involved in the glucose sensing mechanism such as GLUT2, Glucokinase (GK) and Glucokinase regulatory protein (GKRP). GK catalyzes the phosphorylation of glucose to glucose-6-phosphate (G-6P), and its activity and subcellular localization are regulated by GKRP. In liver, when glucose concentration is low, GKRP binds to GK holding it in the nucleus, while the rise in glucose concentration induces a rapid export of GK from the nucleus to the cytoplasm. In contrast, hypothalamic tanycytes display inverse compartmentalization dynamic in response to glucose: a rise in the glucose concentration drives nuclear compartmentalization of GK. The underlying mechanism responsible for differential GK subcellular localization in tanycytes has not been described yet. However, it has been suggested that relative expression between GK and GKRP might play a role. To study the effects of GKRP expression levels in the subcellular localization of GK, we used insulinoma 832/13 cells and hypothalamic tanycytes to overexpress the tanycytic sequences of Gckr. By immunocytochemistry and Western blot analysis, we observed that overexpression of GKRP, independently of the cellular context, turns GK localization to a liver-like fashion, as GK is mainly localized in the nucleus in response to low glucose. Evaluating the expression levels of GKRP in relation to GK through RT-qPCR, suggest that excess of GKRP might influence the pattern of GK subcellular localization. In this sense, we propose that the low expression of GKRP (in relation to GK) observed in tanycytes is responsible, at least in part, for the compartmentalization pattern observed in this cell type. Since GKRP behaves as a GK inhibitor, the regulation of GKRP expression levels or activity in tanycytes could be used as a therapeutic target to regulate the glucosensing activity of these cells and consequently to regulate feeding behavior.
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Affiliation(s)
- Magdiel Salgado
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepción, Concepción, Chile
| | - Patricio Ordenes
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepción, Concepción, Chile
| | - Marcos Villagra
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepción, Concepción, Chile
| | - Elena Uribe
- Department of Biochemistry and Molecular Biology, Faculty of Biological Sciences, University of Concepción, Concepción, Chile
| | | | - Estefanía Tarifeño-Saldivia
- Department of Biochemistry and Molecular Biology, Faculty of Biological Sciences, University of Concepción, Concepción, Chile
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52
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Giaume C, Sáez JC, Song W, Leybaert L, Naus CC. Connexins and pannexins in Alzheimer’s disease. Neurosci Lett 2019; 695:100-105. [DOI: 10.1016/j.neulet.2017.09.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 08/14/2017] [Accepted: 09/01/2017] [Indexed: 12/22/2022]
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53
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Vejar S, Oyarzún JE, Retamal MA, Ortiz FC, Orellana JA. Connexin and Pannexin-Based Channels in Oligodendrocytes: Implications in Brain Health and Disease. Front Cell Neurosci 2019; 13:3. [PMID: 30760982 PMCID: PMC6361860 DOI: 10.3389/fncel.2019.00003] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/07/2019] [Indexed: 11/13/2022] Open
Abstract
Oligodendrocytes are the myelin forming cells in the central nervous system (CNS). In addition to this main physiological function, these cells play key roles by providing energy substrates to neurons as well as information required to sustain proper synaptic transmission and plasticity at the CNS. The latter requires a fine coordinated intercellular communication with neurons and other glial cell types, including astrocytes. In mammals, tissue synchronization is mainly mediated by connexins and pannexins, two protein families that underpin the communication among neighboring cells through the formation of different plasma membrane channels. At one end, gap junction channels (GJCs; which are exclusively formed by connexins in vertebrates) connect the cytoplasm of contacting cells allowing electrical and metabolic coupling. At the other end, hemichannels and pannexons (which are formed by connexins and pannexins, respectively) communicate the intra- and extracellular compartments, serving as diffusion pathways of ions and small molecules. Here, we briefly review the current knowledge about the expression and function of hemichannels, pannexons and GJCs in oligodendrocytes, as well as the evidence regarding the possible role of these channels in metabolic and synaptic functions at the CNS. In particular, we focus on oligodendrocyte-astrocyte coupling during axon metabolic support and its implications in brain health and disease.
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Affiliation(s)
- Sebastián Vejar
- Mechanisms of Myelin Formation and Repair Laboratory, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Juan E Oyarzún
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile.,Department of Cell Physiology and Molecular Biophysics, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Fernando C Ortiz
- Mechanisms of Myelin Formation and Repair Laboratory, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Pontificia Universidad Católica de Chile, Santiago, Chile
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54
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Palma-Chavez A, Konar-Nié M, Órdenes P, Maurelia F, Elizondo-Vega R, Oyarce K, López S, Rojas J, Steinberg X, García-Robles MA, Sepúlveda FJ. Glucose Increase DAGLα Levels in Tanycytes and Its Inhibition Alters Orexigenic and Anorexigenic Neuropeptides Expression in Response to Glucose. Front Endocrinol (Lausanne) 2019; 10:647. [PMID: 31620093 PMCID: PMC6763563 DOI: 10.3389/fendo.2019.00647] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 09/05/2019] [Indexed: 12/11/2022] Open
Abstract
The endocannabinoid system (ECS) is composed of a group of Gi-coupled protein receptors and enzymes, producing and degrading the endocannabinoids, 2-arachidonoylglycerol (2-AG) and N-arachidonoyl-ethanolamine (AEA). Endocannabinoid-mediated signaling modulates brain functions, such as pain, mood, memory, and feeding behavior. The activation of the ECS is associated with overeating and obesity; however, the expression of components of this system has been only partially studied in the hypothalamus, a critical region implicated in feeding behavior. Within this brain region, anorexigenic, and orexigenic neurons of the arcuate nucleus (ARC) are in close contact with tanycytes, glial radial-like cells that line the lateral walls and floor of the third ventricle (3V). The specific function of tanycytes and the effects of metabolic signals generated by them on adjacent neurons is starting to be elucidated. We have proposed that the ECS within tanycytes modulates ARC neurons, thus modifying food intake. Here, we evaluated the expression and the loss of function of the 2-AG-producing enzyme, diacylglycerol lipase-alpha (DAGLα). Using Western blot and immunohistochemistry analyses in basal hypothalamus sections of adult rats under several glycemic conditions, we confirm that DAGLα is strongly expressed at the basal hypothalamus in glial and neuronal cells, increasing further in response to greater extracellular glucose levels. Using a DAGLα-inhibiting adenovirus (shRNA), suppression of DAGLα expression in tanycytes altered the usual response to intracerebroventricular glucose in terms of neuropeptides produced by neurons of the ARC. Thus, these results strongly suggest that the tanycytes could generate 2-AG, which modulates the function of anorexigenic and orexigenic neurons.
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Affiliation(s)
- Alejandra Palma-Chavez
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
- Laboratorio de Bioquímica y Biología Celular, Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Concepción, Chile
| | - Macarena Konar-Nié
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
| | - Patricio Órdenes
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
| | - Felipe Maurelia
- Laboratorio de Bioquímica y Biología Celular, Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Concepción, Chile
| | - Roberto Elizondo-Vega
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
| | - Karina Oyarce
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Concepción, Chile
| | - Sergio López
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
| | - Joaquin Rojas
- Centro de Estudios Avanzados para la Vida (CREAV), Universidad de Concepción, Concepción, Chile
| | - Ximena Steinberg
- Laboratorio de Bioquímica y Biología Celular, Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Concepción, Chile
| | - María A. García-Robles
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
- Centro de Estudios Avanzados para la Vida (CREAV), Universidad de Concepción, Concepción, Chile
- *Correspondence: María A. García-Robles
| | - Fernando J. Sepúlveda
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
- Laboratorio de Bioquímica y Biología Celular, Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Concepción, Chile
- Fernando J. Sepúlveda
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Langlet F. Tanycyte Gene Expression Dynamics in the Regulation of Energy Homeostasis. Front Endocrinol (Lausanne) 2019; 10:286. [PMID: 31133987 PMCID: PMC6514105 DOI: 10.3389/fendo.2019.00286] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 04/18/2019] [Indexed: 01/01/2023] Open
Abstract
Animal survival relies on a constant balance between energy supply and energy expenditure, which is controlled by several neuroendocrine functions that integrate metabolic information and adapt the response of the organism to physiological demands. Polarized ependymoglial cells lining the floor of the third ventricle and sending a single process within metabolic hypothalamic parenchyma, tanycytes are henceforth described as key components of the hypothalamic neural network controlling energy balance. Their strategic position and peculiar properties convey them diverse physiological functions ranging from blood/brain traffic controllers, metabolic modulators, and neural stem/progenitor cells. At the molecular level, these functions rely on an accurate regulation of gene expression. Indeed, tanycytes are characterized by their own molecular signature which is mostly associated to their diverse physiological functions, and the detection of variations in nutrient/hormone levels leads to an adequate modulation of genetic profile in order to ensure energy homeostasis. The aim of this review is to summarize recent knowledge on the nutritional control of tanycyte gene expression.
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Elizondo-Vega RJ, Recabal A, Oyarce K. Nutrient Sensing by Hypothalamic Tanycytes. Front Endocrinol (Lausanne) 2019; 10:244. [PMID: 31040827 PMCID: PMC6476911 DOI: 10.3389/fendo.2019.00244] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 03/27/2019] [Indexed: 01/28/2023] Open
Abstract
Nutritional signals have long been implicated in the control of cellular processes that take place in the hypothalamus. This includes food intake regulation and energy balance, inflammation, and most recently, neurogenesis. One of the main glial cells residing in the hypothalamus are tanycytes, radial glial-like cells, whose bodies are located in the lining of the third ventricle, with processes extending to the parenchyma and reaching neuronal nuclei. Their unique anatomical location makes them directly exposed to nutrients in the cerebrospinal fluid. Several research groups have shown that tanycytes can respond to nutritional signals by different mechanisms, such as calcium signaling, metabolic shift, and changes in proliferation/differentiation potential. Despite cumulative evidence showing tanycytes have the molecular components to participate in nutrient detection and response, there are no enough functional studies connecting tanycyte nutrient sensing with hypothalamic functions, nor that highlight the relevance of this process in physiological and pathological context. This review will summarize recent evidence that supports a nutrient sensor role for tanycytes in the hypothalamus, highlighting the need for more detailed analysis on the actual implications of tanycyte-nutrient sensing and how this process can be modulated, which might allow the discovery of new metabolic and signaling pathways as therapeutic targets, for the treatment of hypothalamic related diseases.
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Affiliation(s)
- Roberto Javier Elizondo-Vega
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Antonia Recabal
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Karina Oyarce
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Concepción, Chile
- *Correspondence: Karina Oyarce
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57
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Abudara V, Retamal MA, Del Rio R, Orellana JA. Synaptic Functions of Hemichannels and Pannexons: A Double-Edged Sword. Front Mol Neurosci 2018; 11:435. [PMID: 30564096 PMCID: PMC6288452 DOI: 10.3389/fnmol.2018.00435] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/08/2018] [Indexed: 01/18/2023] Open
Abstract
The classical view of synapses as the functional contact between presynaptic and postsynaptic neurons has been challenged in recent years by the emerging regulatory role of glial cells. Astrocytes, traditionally considered merely supportive elements are now recognized as active modulators of synaptic transmission and plasticity at the now so-called "tripartite synapse." In addition, an increasing body of evidence indicates that beyond immune functions microglia also participate in various processes aimed to shape synaptic plasticity. Release of neuroactive compounds of glial origin, -process known as gliotransmission-, constitute a widespread mechanism through which glial cells can either potentiate or reduce the synaptic strength. The prevailing vision states that gliotransmission depends on an intracellular Ca2+/exocytotic-mediated release; notwithstanding, growing evidence is pointing at hemichannels (connexons) and pannexin channels (pannexons) as alternative non-vesicular routes for gliotransmitters efflux. In concurrence with this novel concept, both hemichannels and pannexons are known to mediate the transfer of ions and signaling molecules -such as ATP and glutamate- between the cytoplasm and the extracellular milieu. Importantly, recent reports show that glial hemichannels and pannexons are capable to perceive synaptic activity and to respond to it through changes in their functional state. In this article, we will review the current information supporting the "double edge sword" role of hemichannels and pannexons in the function of central and peripheral synapses. At one end, available data support the idea that these channels are chief components of a feedback control mechanism through which gliotransmitters adjust the synaptic gain in either resting or stimulated conditions. At the other end, we will discuss how the excitotoxic release of gliotransmitters and [Ca2+]i overload linked to the opening of hemichannels/pannexons might impact cell function and survival in the nervous system.
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Affiliation(s)
- Verónica Abudara
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile.,Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States.,Programa de Comunicación Celular en Cáncer, Instituto de Ciencias e Innovación en Medicina, Santiago, Chile
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Envejecimiento y Regeneración, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
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Recabal A, Elizondo-Vega R, Philippot C, Salgado M, López S, Palma A, Tarifeño-Saldivia E, Timmermann A, Seifert G, Caprile T, Steinhäuser C, García-Robles MA. Connexin-43 Gap Junctions Are Responsible for the Hypothalamic Tanycyte-Coupled Network. Front Cell Neurosci 2018; 12:406. [PMID: 30534054 PMCID: PMC6275304 DOI: 10.3389/fncel.2018.00406] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 10/19/2018] [Indexed: 12/21/2022] Open
Abstract
Tanycytes are hypothalamic radial glia-like cells that form the basal wall of the third ventricle (3V) where they sense glucose and modulate neighboring neuronal activity to control feeding behavior. This role requires the coupling of hypothalamic cells since transient decreased hypothalamic Cx43 expression inhibits the increase of brain glucose-induced insulin secretion. Tanycytes have been postulated as possible hypothalamic neuronal precursors due to their privileged position in the hypothalamus that allows them to detect mitogenic signals and because they share the markers and characteristics of neuronal precursors located in other neurogenic niches, including the formation of coupled networks through connexins. Using wild-type (WT), Cx30−/– and Cx30−/–, Cx43fl/fl:glial fibrillary acidic protein (GFAP)-Cre (double knockout, dKO) mouse lines, we demonstrated that tanycytes are highly coupled to each other and also give rise to a panglial network specifically through Cx43. Using the human GFAP (hGFAP)-enhanced green fluorescent protein (EGFP) transgenic mouse line, we provided evidence that the main parenchymal-coupled cells were astrocytes. In addition, electrophysiological parameters, such as membrane resistance, were altered when Cx43 was genetically absent or pharmacologically inhibited. Finally, in the dKO mouse line, we detected a significant decrease in the number of hypothalamic proliferative parenchymal cells. Our results demonstrate the importance of Cx43 in tanycyte homotypic and panglial coupling and show that Cx43 function influences the proliferative potential of hypothalamic cells.
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Affiliation(s)
- Antonia Recabal
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Roberto Elizondo-Vega
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Camille Philippot
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn Bonn, Germany
| | - Magdiel Salgado
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Sergio López
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Alejandra Palma
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Estefanía Tarifeño-Saldivia
- Department of Biochemistry and Molecular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Aline Timmermann
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn Bonn, Germany
| | - Gerald Seifert
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn Bonn, Germany
| | - Teresa Caprile
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn Bonn, Germany
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Abstract
Animal models are valuable for the study of complex behaviours and physiology such as the control of appetite because genetic, pharmacological and surgical approaches allow the investigation of underlying mechanisms. However, the majority of such studies are carried out in just two species, laboratory mice and rats. These conventional laboratory species have been intensely selected for high growth rate and fecundity, and have a high metabolic rate and short lifespan. These aspects limit their translational relevance for human appetite control. This review will consider the value of studies carried out in a seasonal species, the Siberian hamster, which shows natural photoperiod-regulated annual cycles in appetite, growth and fattening. Such studies reveal that this long-term control is not simply an adjustment of the known hypothalamic neuronal systems that control hunger and satiety in the short term. Long-term cyclicity is probably driven by hypothalamic tanycytes, glial cells that line the ventricular walls of the hypothalamus. These unique cells sense nutrients and metabolic hormones, integrate seasonal signals and effect plasticity of surrounding neural circuits through their function as a stem cell niche in the adult. Studies of glial cell function in the hypothalamus offer new potential for identifying central targets for appetite and body weight control amenable to dietary or pharmacological manipulation.
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60
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Sáez JC, Contreras-Duarte S, Gómez GI, Labra VC, Santibañez CA, Gajardo-Gómez R, Avendaño BC, Díaz EF, Montero TD, Velarde V, Orellana JA. Connexin 43 Hemichannel Activity Promoted by Pro-Inflammatory Cytokines and High Glucose Alters Endothelial Cell Function. Front Immunol 2018; 9:1899. [PMID: 30158937 PMCID: PMC6104120 DOI: 10.3389/fimmu.2018.01899] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 07/31/2018] [Indexed: 12/13/2022] Open
Abstract
The present work was done to elucidate whether hemichannels of a cell line derived from endothelial cells are affected by pro-inflammatory conditions (high glucose and IL-1β/TNF-α) known to lead to vascular dysfunction. We used EAhy 926 cells treated with high glucose and IL-1β/TNF-α. The hemichannel activity was evaluated with the dye uptake method and was abrogated with selective inhibitors or knocking down of hemichannel protein subunits with siRNA. Western blot analysis, cell surface biotinylation, and confocal microscopy were used to evaluate total and plasma membrane amounts of specific proteins and their cellular distribution, respectively. Changes in intracellular Ca2+ and nitric oxide (NO) signals were estimated by measuring FURA-2 and DAF-FM probes, respectively. High glucose concentration was found to elevate dye uptake, a response that was enhanced by IL-1β/TNF-α. High glucose plus IL-1β/TNF-α-induced dye uptake was abrogated by connexin 43 (Cx43) but not pannexin1 knockdown. Furthermore, Cx43 hemichannel activity was associated with enhanced ATP release and activation of p38 MAPK, inducible NO synthase, COX2, PGE2 receptor EP1, and P2X7/P2Y1 receptors. Inhibition of the above pathways prevented completely the increase in Cx43 hemichannel activity of cells treated high glucose and IL-1β/TNF-α. Both synthetic and endogenous cannabinoids (CBs) also prevented the increment in Cx43 hemichannel opening, as well as the subsequent generation and release of ATP and NO induced by pro-inflammatory conditions. The counteracting action of CBs also was extended to other endothelial alterations evoked by IL-1β/TNF-α and high glucose, including increased ATP-dependent Ca2+ dynamics and insulin-induced NO production. Finally, inhibition of Cx43 hemichannels also prevented the ATP release from endothelial cells treated with IL-1β/TNF-α and high glucose. Therefore, we propose that reduction of hemichannel activity could represent a strategy against the activation of deleterious pathways that lead to endothelial dysfunction and possibly cell damage evoked by high glucose and pro-inflammatory conditions during cardiovascular diseases.
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Affiliation(s)
- Juan C Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago de Chile, Chile.,Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Susana Contreras-Duarte
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago de Chile, Chile.,Departamento de Ginecología y Obstetricia, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Gonzalo I Gómez
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Valeria C Labra
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Cristian A Santibañez
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rosario Gajardo-Gómez
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Beatriz C Avendaño
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Esteban F Díaz
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Trinidad D Montero
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Victoria Velarde
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago de Chile, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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61
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Prevot V, Dehouck B, Sharif A, Ciofi P, Giacobini P, Clasadonte J. The Versatile Tanycyte: A Hypothalamic Integrator of Reproduction and Energy Metabolism. Endocr Rev 2018; 39:333-368. [PMID: 29351662 DOI: 10.1210/er.2017-00235] [Citation(s) in RCA: 147] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 01/12/2018] [Indexed: 12/16/2022]
Abstract
The fertility and survival of an individual rely on the ability of the periphery to promptly, effectively, and reproducibly communicate with brain neural networks that control reproduction, food intake, and energy homeostasis. Tanycytes, a specialized glial cell type lining the wall of the third ventricle in the median eminence of the hypothalamus, appear to act as the linchpin of these processes by dynamically controlling the secretion of neuropeptides into the portal vasculature by hypothalamic neurons and regulating blood-brain and blood-cerebrospinal fluid exchanges, both processes that depend on the ability of these cells to adapt their morphology to the physiological state of the individual. In addition to their barrier properties, tanycytes possess the ability to sense blood glucose levels, and play a fundamental and active role in shuttling circulating metabolic signals to hypothalamic neurons that control food intake. Moreover, accumulating data suggest that, in keeping with their putative descent from radial glial cells, tanycytes are endowed with neural stem cell properties and may respond to dietary or reproductive cues by modulating hypothalamic neurogenesis. Tanycytes could thus constitute the missing link in the loop connecting behavior, hormonal changes, signal transduction, central neuronal activation and, finally, behavior again. In this article, we will examine these recent advances in the understanding of tanycytic plasticity and function in the hypothalamus and the underlying molecular mechanisms. We will also discuss the putative involvement and therapeutic potential of hypothalamic tanycytes in metabolic and fertility disorders.
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Affiliation(s)
- Vincent Prevot
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Center, Lille, France.,University of Lille, FHU 1000 Days for Health, School of Medicine, Lille, France
| | - Bénédicte Dehouck
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Center, Lille, France.,University of Lille, FHU 1000 Days for Health, School of Medicine, Lille, France
| | - Ariane Sharif
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Center, Lille, France.,University of Lille, FHU 1000 Days for Health, School of Medicine, Lille, France
| | - Philippe Ciofi
- Inserm, Neurocentre Magendie, Bordeaux, France.,Université de Bordeaux, Bordeaux, France
| | - Paolo Giacobini
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Center, Lille, France.,University of Lille, FHU 1000 Days for Health, School of Medicine, Lille, France
| | - Jerome Clasadonte
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Center, Lille, France.,University of Lille, FHU 1000 Days for Health, School of Medicine, Lille, France
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62
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Raikwar SP, Bhagavan SM, Ramaswamy SB, Thangavel R, Dubova I, Selvakumar GP, Ahmed ME, Kempuraj D, Zaheer S, Iyer S, Zaheer A. Are Tanycytes the Missing Link Between Type 2 Diabetes and Alzheimer's Disease? Mol Neurobiol 2018; 56:833-843. [PMID: 29797185 DOI: 10.1007/s12035-018-1123-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/11/2018] [Indexed: 10/16/2022]
Abstract
Tanycytes are highly specialized bipolar ependymal cells that line the ventrolateral wall and the floor of the third ventricle in the brain and form a blood-cerebrospinal fluid barrier at the level of the median eminence. They play a pivotal role in regulating metabolic networks that control body weight and energy homeostasis. Due to the glucosensing function of tanycytes, they could be considered as a critical player in the pathogenesis of type 2 diabetes. Genetic fate mapping studies have established the role of tanycytes for the newly detected adult hypothalamic neurogenesis with important implications for metabolism as well as pathophysiology of various neurodegenerative diseases. We believe that a comprehensive understanding of the physiological mechanisms underlying their neuroplasticity, glucosensing, and cross talk with endothelial cells will enable us to achieve metabolic homeostasis in type 2 diabetes patients and possibly delay the progression of Alzheimer's disease and hopefully improve cognitive function.
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Affiliation(s)
- Sudhanshu P Raikwar
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA.,U.S. Department of Veterans Affairs, Harry S. Truman Memorial Veteran's Hospital, Columbia, MO, USA
| | - Sachin M Bhagavan
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA
| | - Swathi Beladakere Ramaswamy
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA
| | - Ramasamy Thangavel
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA.,U.S. Department of Veterans Affairs, Harry S. Truman Memorial Veteran's Hospital, Columbia, MO, USA
| | - Iuliia Dubova
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA
| | - Govindhasamy Pushpavathi Selvakumar
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA.,U.S. Department of Veterans Affairs, Harry S. Truman Memorial Veteran's Hospital, Columbia, MO, USA
| | - Mohammad Ejaz Ahmed
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA.,U.S. Department of Veterans Affairs, Harry S. Truman Memorial Veteran's Hospital, Columbia, MO, USA
| | - Duraisamy Kempuraj
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA.,U.S. Department of Veterans Affairs, Harry S. Truman Memorial Veteran's Hospital, Columbia, MO, USA
| | - Smita Zaheer
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA
| | - Shankar Iyer
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA.,U.S. Department of Veterans Affairs, Harry S. Truman Memorial Veteran's Hospital, Columbia, MO, USA
| | - Asgar Zaheer
- Department of Neurology, Center for Translational Neuroscience, School of Medicine, University of Missouri, M741A Medical Science Building, 1 Hospital Drive, Columbia, MO, 65211, USA. .,U.S. Department of Veterans Affairs, Harry S. Truman Memorial Veteran's Hospital, Columbia, MO, USA.
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63
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López-Gambero AJ, Martínez F, Salazar K, Cifuentes M, Nualart F. Brain Glucose-Sensing Mechanism and Energy Homeostasis. Mol Neurobiol 2018; 56:769-796. [PMID: 29796992 DOI: 10.1007/s12035-018-1099-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/25/2018] [Indexed: 01/02/2023]
Abstract
The metabolic and energy state of the organism depends largely on the availability of substrates, such as glucose for ATP production, necessary for maintaining physiological functions. Deregulation in glucose levels leads to the appearance of pathological signs that result in failures in the cardiovascular system and various diseases, such as diabetes, obesity, nephropathy, and neuropathy. Particularly, the brain relies on glucose as fuel for the normal development of neuronal activity. Regions adjacent to the cerebral ventricles, such as the hypothalamus and brainstem, exercise central control in energy homeostasis. These centers house nuclei of neurons whose excitatory activity is sensitive to changes in glucose levels. Determining the different detection mechanisms, the phenotype of neurosecretion, and neural connections involving glucose-sensitive neurons is essential to understanding the response to hypoglycemia through modulation of food intake, thermogenesis, and activation of sympathetic and parasympathetic branches, inducing glucagon and epinephrine secretion and other hypothalamic-pituitary axis-dependent counterregulatory hormones, such as glucocorticoids and growth hormone. The aim of this review focuses on integrating the current understanding of various glucose-sensing mechanisms described in the brain, thereby establishing a relationship between neuroanatomy and control of physiological processes involved in both metabolic and energy balance. This will advance the understanding of increasingly prevalent diseases in the modern world, especially diabetes, and emphasize patterns that regulate and stimulate intake, thermogenesis, and the overall synergistic effect of the neuroendocrine system.
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Affiliation(s)
- A J López-Gambero
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile.,Department of Cell Biology, Genetics and Physiology, University of Malaga, IBIMA, BIONAND, Andalusian Center for Nanomedicine and Biotechnology and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine, Málaga, Spain
| | - F Martínez
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
| | - K Salazar
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
| | - M Cifuentes
- Department of Cell Biology, Genetics and Physiology, University of Malaga, IBIMA, BIONAND, Andalusian Center for Nanomedicine and Biotechnology and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine, Málaga, Spain.
| | - F Nualart
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile. .,Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
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64
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Angiotensin II-Induced Mesangial Cell Damaged Is Preceded by Cell Membrane Permeabilization Due to Upregulation of Non-Selective Channels. Int J Mol Sci 2018; 19:ijms19040957. [PMID: 29570626 PMCID: PMC5979336 DOI: 10.3390/ijms19040957] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 03/20/2018] [Accepted: 03/20/2018] [Indexed: 02/07/2023] Open
Abstract
Connexin43 (Cx43), pannexin1 (Panx1) and P2X7 receptor (P2X7R) are expressed in kidneys and are known to constitute a feedforward mechanism leading to inflammation in other tissues. However, the possible functional relationship between these membrane channels and their role in damaged renal cells remain unknown. In the present work, we found that MES-13 cells, from a cell line derived from mesangial cells, stimulated with angiotensin II (AngII) developed oxidative stress (OS, thiobarbituric acid reactive species (TBARS) and generated pro-inflammatory cytokines (ELISA; IL-1β and TNF-α). The membrane permeability increased progressively several hours before the latter outcome, which was a response prevented by Losartan, indicating the involvement of AT1 receptors. Western blot analysis showed that the amount of phosphorylated MYPT (a substrate of RhoA/ROCK) and Cx43 increased progressively and in parallel in cells treated with AngII, a response followed by an increase in the amount in Panx1 and P2X7R. Greater membrane permeability was partially explained by opening of Cx43 hemichannels (Cx43 HCs) and Panx1 channels (Panx1 Chs), as well as P2X7Rs activation by extracellular ATP, which was presumably released via Cx HCs and Panx1 Chs. Additionally, inhibition of RhoA/ROCK blocked the progressive increase in membrane permeability, and the remaining response was explained by the other non-selective channels. The rise of activity in the RhoA/ROCK-dependent pathway, as well as in Cx HCs, P2X7R, and to a minor extent in Panx1 Chs led to higher amounts of TBARS and pro-inflammatory cytokines. We propose that AngII-induced mesangial cell damage could be effectively inhibited by concomitantly inhibiting the RhoA/ROCK-dependent pathway and one or more non-selective channel(s) activated through this pathway.
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65
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Labra VC, Santibáñez CA, Gajardo-Gómez R, Díaz EF, Gómez GI, Orellana JA. The Neuroglial Dialog Between Cannabinoids and Hemichannels. Front Mol Neurosci 2018; 11:79. [PMID: 29662436 PMCID: PMC5890195 DOI: 10.3389/fnmol.2018.00079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 02/28/2018] [Indexed: 12/11/2022] Open
Abstract
The formation of gap junctions was initially thought to be the central role of connexins, however, recent evidence had brought to light the high relevance of unopposed hemichannels as an independent mechanism for the selective release of biomolecules during physiological and pathological conditions. In the healthy brain, the physiological opening of astrocyte hemichannels modulates basal excitatory synaptic transmission. At the other end, the release of potentially neurotoxic compounds through astroglial hemichannels and pannexons has been insinuated as one of the functional alterations that negatively affect the progression of multiple brain diseases. Recent insights in this matter have suggested encannabinoids (eCBs) as molecules that could regulate the opening of these channels during diverse conditions. In this review, we discuss and hypothesize the possible interplay between the eCB system and the hemichannel/pannexon-mediated signaling in the inflamed brain and during event of synaptic plasticity. Most findings indicate that eCBs seem to counteract the activation of major neuroinflammatory pathways that lead to glia-mediated production of TNF-α and IL-1β, both well-known triggers of astroglial hemichannel opening. In contrast to the latter, in the normal brain, eCBs apparently elicit the Ca2+-activation of astrocyte hemichannels, which could have significant consequences on eCB-dependent synaptic plasticity.
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Affiliation(s)
- Valeria C Labra
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| | - Cristian A Santibáñez
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| | - Rosario Gajardo-Gómez
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| | - Esteban F Díaz
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| | - Gonzalo I Gómez
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
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66
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Ebling FJP, Lewis JE. Tanycytes and hypothalamic control of energy metabolism. Glia 2018; 66:1176-1184. [DOI: 10.1002/glia.23303] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 12/21/2017] [Accepted: 01/23/2018] [Indexed: 01/15/2023]
Affiliation(s)
- Francis J. P. Ebling
- School of Life Sciences; University of Nottingham Medical School, Queen's Medical Centre; Nottingham NG7 2UH United Kingdom
| | - Jo E. Lewis
- School of Life Sciences; University of Nottingham Medical School, Queen's Medical Centre; Nottingham NG7 2UH United Kingdom
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67
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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68
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Zhou YD. Glial Regulation of Energy Metabolism. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1090:105-121. [DOI: 10.1007/978-981-13-1286-1_6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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69
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 891] [Impact Index Per Article: 148.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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70
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Stevenson TJ, Alward BA, Ebling FJP, Fernald RD, Kelly A, Ophir AG. The Value of Comparative Animal Research: Krogh's Principle Facilitates Scientific Discoveries. ACTA ACUST UNITED AC 2017; 5:118-125. [PMID: 32743064 DOI: 10.1177/2372732217745097] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Biomedical research is dominated by relatively few nonhuman animals to investigate healthy and disease conditions. Research has overrelied on these models due to their well-described genomes, the capability to control specific genes, and the high rate of reproduction. However, recent advances in large-scale molecular sequencing experiments have revealed, in some cases, the limited similarities in experimental outcomes observed in common rodents (i.e., mice) compared with humans. The value of more varied comparative animal models includes examples such as long-term body weight regulation in seasonally breeding hamsters as a means to help understand the obesity epidemic, vocal learning in songbirds to illuminate language acquisition and maintenance, and reproduction in cichlid fish to discover novel genes conserved in humans. Studying brain genes in prairie voles and cichlids advanced knowledge about social behavior. Taken together, experiments on diverse animal species highlight nontraditional systems for advancing our understanding of human health and well-being.
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71
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Barahona MJ, Llanos P, Recabal A, Escobar-Acuña K, Elizondo-Vega R, Salgado M, Ordenes P, Uribe E, Sepúlveda FJ, Araneda RC, García-Robles MA. Glial hypothalamic inhibition of GLUT2 expression alters satiety, impacting eating behavior. Glia 2017; 66:592-605. [PMID: 29178321 PMCID: PMC5814884 DOI: 10.1002/glia.23267] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 10/31/2017] [Accepted: 11/07/2017] [Indexed: 12/22/2022]
Abstract
Glucose is a key modulator of feeding behavior. By acting in peripheral tissues and in the central nervous system, it directly controls the secretion of hormones and neuropeptides and modulates the activity of the autonomic nervous system. GLUT2 is required for several glucoregulatory responses in the brain, including feeding behavior, and is localized in the hypothalamus and brainstem, which are the main centers that control this behavior. In the hypothalamus, GLUT2 has been detected in glial cells, known as tanycytes, which line the basal walls of the third ventricle (3V). This study aimed to clarify the role of GLUT2 expression in tanycytes in feeding behavior using 3V injections of an adenovirus encoding a shRNA against GLUT2 and the reporter EGFP (Ad‐shGLUT2). Efficient in vivo GLUT2 knockdown in rat hypothalamic tissue was demonstrated by qPCR and Western blot analyses. Specificity of cell transduction in the hypothalamus and brainstem was evaluated by EGFP‐fluorescence and immunohistochemistry, which showed EGFP expression specifically in ependymal cells, including tanycytes. The altered mRNA levels of both orexigenic and anorexigenic neuropeptides suggested a loss of response to increased glucose in the 3V. Feeding behavior analysis in the fasting‐feeding transition revealed that GLUT2‐knockdown rats had increased food intake and body weight, suggesting an inhibitory effect on satiety. Taken together, suppression of GLUT2 expression in tanycytes disrupted the hypothalamic glucosensing mechanism, which altered the feeding behavior.
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Affiliation(s)
- María J Barahona
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Paula Llanos
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Antonia Recabal
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Kathleen Escobar-Acuña
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Roberto Elizondo-Vega
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.,Laboratorio de Inmunología Celular y Molecular, Centro de Investigación Biomédica, Facultad de Medicina, Universidad de los Andes, Santiago, Chile
| | - Magdiel Salgado
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Patricio Ordenes
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Elena Uribe
- Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Chile
| | - Fernando J Sepúlveda
- Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Chile.,Departamento de Ciencias Biológica Universidad Andrés Bello, Concepción, Chile
| | - Ricardo C Araneda
- Department of Biology, University of Maryland, College Park, Maryland
| | - María A García-Robles
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
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72
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Lazutkaite G, Soldà A, Lossow K, Meyerhof W, Dale N. Amino acid sensing in hypothalamic tanycytes via umami taste receptors. Mol Metab 2017; 6:1480-1492. [PMID: 29107294 PMCID: PMC5681271 DOI: 10.1016/j.molmet.2017.08.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 08/25/2017] [Accepted: 08/30/2017] [Indexed: 12/15/2022] Open
Abstract
Objective Hypothalamic tanycytes are glial cells that line the wall of the third ventricle and contact the cerebrospinal fluid (CSF). While they are known to detect glucose in the CSF we now show that tanycytes also detect amino acids, important nutrients that signal satiety. Methods Ca2+ imaging and ATP biosensing were used to detect tanycyte responses to l-amino acids. The downstream pathway of the responses was determined using ATP receptor antagonists and channel blockers. The receptors were characterized using mice lacking the Tas1r1 gene, as well as an mGluR4 receptor antagonist. Results Amino acids such as Arg, Lys, and Ala evoke Ca2+ signals in tanycytes and evoke the release of ATP via pannexin 1 and CalHM1, which amplifies the signal via a P2 receptor dependent mechanism. Tanycytes from mice lacking the Tas1r1 gene had diminished responses to lysine and arginine but not alanine. Antagonists of mGluR4 greatly reduced the responses to alanine and lysine. Conclusion Two receptors previously implicated in taste cells, the Tas1r1/Tas1r3 heterodimer and mGluR4, contribute to the detection of a range of amino acids by tanycytes in CSF. Hypothalamic tanycytes can detect amino acids in cerebrospinal fluid. The mechanism is taste receptor-dependent. Tas1r1/Tas1r3 mediates responses to l-arginine and l-lysine. mGluR4 mediates responses to l-alanine and partially those of l-lysine. ATP release from tanycytes evoked by amino acids reaches into the arcuate nucleus.
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Affiliation(s)
- Greta Lazutkaite
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Alice Soldà
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Kristina Lossow
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany
| | - Wolfgang Meyerhof
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany
| | - Nicholas Dale
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
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Tanycytes control the hormonal output of the hypothalamic-pituitary-thyroid axis. Nat Commun 2017; 8:484. [PMID: 28883467 PMCID: PMC5589884 DOI: 10.1038/s41467-017-00604-6] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 07/13/2017] [Indexed: 12/29/2022] Open
Abstract
The hypothalamic–pituitary–thyroid (HPT) axis maintains circulating thyroid hormone levels in a narrow physiological range. As axons containing thyrotropin-releasing hormone (TRH) terminate on hypothalamic tanycytes, these specialized glial cells have been suggested to influence the activity of the HPT axis, but their exact role remained enigmatic. Here, we demonstrate that stimulation of the TRH receptor 1 increases intracellular calcium in tanycytes of the median eminence via Gαq/11 proteins. Activation of Gαq/11 pathways increases the size of tanycyte endfeet that shield pituitary vessels and induces the activity of the TRH-degrading ectoenzyme. Both mechanisms may limit the TRH release to the pituitary. Indeed, blocking TRH signaling in tanycytes by deleting Gαq/11 proteins in vivo enhances the response of the HPT axis to the chemogenetic activation of TRH neurons. In conclusion, we identify new TRH- and Gαq/11-dependent mechanisms in the median eminence by which tanycytes control the activity of the HPT axis. The hypothalamic-pituitary-thyroid (HPT) axis regulates a wide range of physiological processes. Here the authors show that hypothalamic tanycytes play a role in the homeostatic regulation of the HPT axis; activation of TRH signaling in tanycytes elevates their intracellular Ca2+ via Gαq/11 pathway, ultimately resulting in reduced TRH release into the pituitary vessels.
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Szilvásy-Szabó A, Varga E, Beliczai Z, Lechan RM, Fekete C. Localization of connexin 43 gap junctions and hemichannels in tanycytes of adult mice. Brain Res 2017; 1673:64-71. [PMID: 28803831 DOI: 10.1016/j.brainres.2017.08.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 06/22/2017] [Accepted: 08/09/2017] [Indexed: 12/22/2022]
Abstract
Tanycytes are specialized glial cells lining the lateral walls and the floor of the third ventricle behind the optic chiasm. In addition to functioning as barrier cells, they also have an important role in the regulation of neuroendocrine axes and energy homeostasis. To determine whether tanycytes communicate with each other via Connexin 43 (Cx43) gap junctions, individual tanycytes were loaded with Lucifer yellow (LY) through a patch pipette. In all cases, LY filled a larger group of tanycytes as well as blood vessels adjacent to tanycyte processes. The Cx43-blocker, carbenoxolone, inhibited spreading of LY. The greatest density of Cx43-immunoreactive spots was observed in the cell membrane of α-tanycyte cell bodies. Cx43-immunoreactivity was also present in the membrane of β-tanycyte cell bodies, but in lower density. Processes of both types of tanycytes also contained Cx43-immunoreactivity. At the ultrastructural level, Cx43-immunoreactivity was present in the cell membrane of all types of tanycytes including their ventricular surface, but gap junctions were more frequent among α-tanycytes. Cx43-immunoreactivity was also observed in the cell membrane between contacting tanycyte endfeet processes, and between tanycyte endfeet process and axon varicosities in the external zone of the median eminence and capillaries in the arcuate nucleus and median eminence. These results suggest that gap junctions are present not only among tanycytes, but also between tanycytes and the axons of hypophysiotropic neurons. Cx43 hemichannels may also facilitate the transport between tanycytes and extracellular fluids, including the cerebrospinal fluid, extracellular space of the median eminence and bloodstream.
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Affiliation(s)
- Anett Szilvásy-Szabó
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary; Semmelweis University Neurosciences Doctoral School, Neuroendocrinology Program, Budapest, Hungary
| | - Edina Varga
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Zsuzsa Beliczai
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Ronald M Lechan
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, MA, USA; Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Csaba Fekete
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary; Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, MA, USA.
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Michael NJ, Simonds SE, van den Top M, Cowley MA, Spanswick D. Mitochondrial uncoupling in the melanocortin system differentially regulates NPY and POMC neurons to promote weight-loss. Mol Metab 2017; 6:1103-1112. [PMID: 29031712 PMCID: PMC5641603 DOI: 10.1016/j.molmet.2017.07.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/29/2017] [Accepted: 07/05/2017] [Indexed: 12/13/2022] Open
Abstract
Objective The mitochondrial uncoupling agent 2,4-dinitrophenol (DNP), historically used as a treatment for obesity, is known to cross the blood-brain-barrier, but its effects on central neural circuits controlling body weight are largely unknown. As hypothalamic melanocortin neuropeptide Y/agouti-related protein (NPY/AgRP) and pro-opiomelanocortin (POMC) neurons represent key central regulators of food intake and energy expenditure we investigated the effects of DNP on these neurons, food intake and energy expenditure. Method C57BL/6 and melanocortin-4 receptor (MC4R) knock-out mice were administered DNP intracerebroventricularly (ICV) and the metabolic changes were characterized. The specific role of NPY and POMC neurons and the ionic mechanisms mediating the effects of uncoupling were examined with in vitro electrophysiology performed on NPY hrGFP or POMC eGFP mice. Results Here we show DNP-induced differential effects on melanocortin neurons including inhibiting orexigenic NPY and activating anorexigenic POMC neurons through independent ionic mechanisms coupled to mitochondrial function, consistent with an anorexigenic central effect. Central administration of DNP induced weight-loss, increased BAT thermogenesis and browning of white adipose tissue, and decreased food intake, effects that were absent in MC4R knock-out mice and blocked by the MC4R antagonist, AgRP. Conclusion These data show a novel central anti-obesity mechanism of action of DNP and highlight the potential for selective melanocortin mitochondrial uncoupling to target metabolic disorders. Mitochondrial uncoupling of the melanocortin system with DNP induced weight-loss. DNP inhibited NPY neurones via activation of ATP-sensitive potassium channels. DNP activated POMC neurones via block of inwardly rectifying potassium channels. Central DNP reduced food intake and increased WAT browning and BAT thermogenesis.
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Affiliation(s)
- Natalie Jane Michael
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Australia(5).
| | - Stephanie Elise Simonds
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Australia(5).
| | | | - Michael Alexander Cowley
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Australia(5).
| | - David Spanswick
- Neuroscience Program, Biomedicine Discovery Institute, Monash University, Australia(5); Neurosolutions, Coventry, P.O. 3517, UK; Metabolic and Vascular Health, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK.
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Kohno D. Sweet taste receptor in the hypothalamus: a potential new player in glucose sensing in the hypothalamus. J Physiol Sci 2017; 67:459-465. [PMID: 28378265 PMCID: PMC10717116 DOI: 10.1007/s12576-017-0535-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/24/2017] [Indexed: 01/06/2023]
Abstract
The hypothalamic feeding center plays an important role in energy homeostasis. The feeding center senses the systemic energy status by detecting hormone and nutrient levels for homeostatic regulation, resulting in the control of food intake, heat production, and glucose production and uptake. The concentration of glucose is sensed by two types of glucose-sensing neurons in the feeding center: glucose-excited neurons and glucose-inhibited neurons. Previous studies have mainly focused on glucose metabolism as the mechanism underlying glucose sensing. Recent studies have indicated that receptor-mediated pathways also play a role in glucose sensing. This review describes sweet taste receptors in the hypothalamus and explores the role of sweet taste receptors in energy homeostasis.
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Affiliation(s)
- Daisuke Kohno
- Advanced Scientific Research Leaders Development Unit, Gunma University, 3-39-15 Showa-machi, Maebashi, Gunma, 371-8512, Japan.
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, 371-8512, Japan.
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Abstract
Glucokinase (GK), the hexokinase involved in glucosensing in pancreatic β-cells, is also expressed in arcuate nucleus (AN) neurons and hypothalamic tanycytes, the cells that surround the basal third ventricle (3V). Several lines of evidence suggest that tanycytes may be involved in the regulation of energy homeostasis. Tanycytes have extended cell processes that contact the feeding-regulating neurons in the AN, particularly, agouti-related protein (AgRP), neuropeptide Y (NPY), cocaine- and amphetamine-regulated transcript (CART) and proopiomelanocortin (POMC) neurons. In this study, we developed an adenovirus expressing GK shRNA to inhibit GK expression in vivo. When injected into the 3V of rats, this adenovirus preferentially transduced tanycytes. qRT-PCR and Western blot assays confirmed GK mRNA and protein levels were lower in GK knockdown animals compared to the controls. In response to an intracerebroventricular glucose injection, the mRNA levels of anorexigenic POMC and CART and orexigenic AgRP and NPY neuropeptides were altered in GK knockdown animals. Similarly, food intake, meal duration, frequency of eating events and the cumulative eating time were increased, whereas the intervals between meals were decreased in GK knockdown rats, suggesting a decrease in satiety. Thus, GK expression in the ventricular cells appears to play an important role in feeding behavior.
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78
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Stevenson TJ, Kumar V. Neural control of daily and seasonal timing of songbird migration. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:399-409. [DOI: 10.1007/s00359-017-1193-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 06/02/2017] [Accepted: 06/03/2017] [Indexed: 12/22/2022]
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Recabal A, Caprile T, García-Robles MDLA. Hypothalamic Neurogenesis as an Adaptive Metabolic Mechanism. Front Neurosci 2017; 11:190. [PMID: 28424582 PMCID: PMC5380718 DOI: 10.3389/fnins.2017.00190] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 03/21/2017] [Indexed: 12/12/2022] Open
Abstract
In the adult brain, well-characterized neurogenic niches are located in the subventricular zone (SVZ) of the lateral ventricles and in the subgranular zone (SGZ) of the hippocampus. In both regions, neural precursor cells (NPCs) share markers of embryonic radial glia and astroglial cells, and in vitro clonal expansion of these cells leads to neurosphere formation. It has also been more recently demonstrated that neurogenesis occurs in the adult hypothalamus, a brain structure that integrates peripheral signals to control energy balance and dietary intake. The NPCs of this region, termed tanycytes, are ependymal-glial cells, which comprise the walls of the infundibular recess of the third ventricle and contact the median eminence. Thus, tanycytes are in a privileged position to detect hormonal, nutritional and mitogenic signals. Recent studies reveal that in response to nutritional signals, tanycytes are capable of differentiating into orexigenic or anorexigenic neurons, suggesting that these cells are crucial for control of feeding behavior. In this review, we discuss evidence, which suggests that hypothalamic neurogenesis may act as an additional adaptive mechanism in order to respond to changes in diet.
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Affiliation(s)
- Antonia Recabal
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de ConcepciónConcepción, Chile.,Laboratorio de Guía Axonal, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de ConcepciónConcepción, Chile
| | - Teresa Caprile
- Laboratorio de Guía Axonal, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de ConcepciónConcepción, Chile
| | - María de Los Angeles García-Robles
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de ConcepciónConcepción, Chile
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Freire-Regatillo A, Argente-Arizón P, Argente J, García-Segura LM, Chowen JA. Non-Neuronal Cells in the Hypothalamic Adaptation to Metabolic Signals. Front Endocrinol (Lausanne) 2017; 8:51. [PMID: 28377744 PMCID: PMC5359311 DOI: 10.3389/fendo.2017.00051] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/03/2017] [Indexed: 12/19/2022] Open
Abstract
Although the brain is composed of numerous cell types, neurons have received the vast majority of attention in the attempt to understand how this organ functions. Neurons are indeed fundamental but, in order for them to function correctly, they rely on the surrounding "non-neuronal" cells. These different cell types, which include glia, epithelial cells, pericytes, and endothelia, supply essential substances to neurons, in addition to protecting them from dangerous substances and situations. Moreover, it is now clear that non-neuronal cells can also actively participate in determining neuronal signaling outcomes. Due to the increasing problem of obesity in industrialized countries, investigation of the central control of energy balance has greatly increased in attempts to identify new therapeutic targets. This has led to interesting advances in our understanding of how appetite and systemic metabolism are modulated by non-neuronal cells. For example, not only are nutrients and hormones transported into the brain by non-neuronal cells, but these cells can also metabolize these metabolic factors, thus modifying the signals reaching the neurons. The hypothalamus is the main integrating center of incoming metabolic and hormonal signals and interprets this information in order to control appetite and systemic metabolism. Hence, the factors transported and released from surrounding non-neuronal cells will undoubtedly influence metabolic homeostasis. This review focuses on what is known to date regarding the involvement of different cell types in the transport and metabolism of nutrients and hormones in the hypothalamus. The possible involvement of non-neuronal cells, in particular glial cells, in physiopathological outcomes of poor dietary habits and excess weight gain are also discussed.
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Affiliation(s)
- Alejandra Freire-Regatillo
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación la Princesa, Madrid, Spain
- Department of Pediatrics, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red: Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Madrid, Spain
| | - Pilar Argente-Arizón
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación la Princesa, Madrid, Spain
- Department of Pediatrics, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red: Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Madrid, Spain
| | - Jesús Argente
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación la Princesa, Madrid, Spain
- Department of Pediatrics, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red: Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Madrid, Spain
- IMDEA Food Institute, Campus of International Excellence (CEI) UAM + CSIC, Madrid, Spain
| | - Luis Miguel García-Segura
- Laboratory of Neuroactive Steroids, Department of Functional and Systems Neurobiology, Instituto Cajal, CSIC (Consejo Superior de Investigaciones Científicas), Madrid, Spain
- Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Madrid, Spain
| | - Julie A. Chowen
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación la Princesa, Madrid, Spain
- Centro de Investigación Biomédica en Red: Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Madrid, Spain
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Benford H, Bolborea M, Pollatzek E, Lossow K, Hermans-Borgmeyer I, Liu B, Meyerhof W, Kasparov S, Dale N. A sweet taste receptor-dependent mechanism of glucosensing in hypothalamic tanycytes. Glia 2017; 65:773-789. [PMID: 28205335 PMCID: PMC5363357 DOI: 10.1002/glia.23125] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 02/01/2023]
Abstract
Hypothalamic tanycytes are glial‐like glucosensitive cells that contact the cerebrospinal fluid of the third ventricle, and send processes into the hypothalamic nuclei that control food intake and body weight. The mechanism of tanycyte glucosensing remains undetermined. While tanycytes express the components associated with the glucosensing of the pancreatic β cell, they respond to nonmetabolisable glucose analogues via an ATP receptor‐dependent mechanism. Here, we show that tanycytes in rodents respond to non‐nutritive sweeteners known to be ligands of the sweet taste (Tas1r2/Tas1r3) receptor. The initial sweet tastant‐evoked response, which requires the presence of extracellular Ca2+, leads to release of ATP and a larger propagating Ca2+ response mediated by P2Y1 receptors. In Tas1r2 null mice the proportion of glucose nonresponsive tanycytes was greatly increased in these mice, but a subset of tanycytes retained an undiminished sensitivity to glucose. Our data demonstrate that the sweet taste receptor mediates glucosensing in about 60% of glucosensitive tanycytes while the remaining 40% of glucosensitive tanycytes use some other, as yet unknown mechanism.
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Affiliation(s)
- Heather Benford
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Matei Bolborea
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Eric Pollatzek
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Kristina Lossow
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, Nuthetal, 14558, Germany
| | - Irm Hermans-Borgmeyer
- Transgenic Animal Unit, University Medical Center Hamburg-Eppendorf, Martinistr. 52, Hamburg, 20246, Germany
| | - Beihui Liu
- School of Physiology and Pharmacology, University of Bristol, United Kingdom
| | - Wolfgang Meyerhof
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, Nuthetal, 14558, Germany
| | - Sergey Kasparov
- School of Physiology and Pharmacology, University of Bristol, United Kingdom
| | - Nicholas Dale
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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Kadłubowska J, Malaguarnera L, Wąż P, Zorena K. Neurodegeneration and Neuroinflammation in Diabetic Retinopathy: Potential Approaches to Delay Neuronal Loss. Curr Neuropharmacol 2017; 14:831-839. [PMID: 27306035 PMCID: PMC5333588 DOI: 10.2174/1570159x14666160614095559] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/1970] [Revised: 08/11/2015] [Accepted: 01/01/1970] [Indexed: 02/06/2023] Open
Abstract
In spite of the extensive research the complex pathogenesis of diabetic retinopathy (DR) has not been fully elucidated. For many years it has been thought that diabetic retinopathy manifests only with microangiopathic lesions, which are totally responsible for the loss of vision in diabetic patients. In view of the current knowledge on the microangiopathic changes in the fundus of the eye, diabetic retinopathy is perceived as a neurodegenerative disease. Several clinical tools are available to detect neuronal dysfunction at early stages of diabetes. Many functional changes in the retina can be identified before vascular pathology develops, suggesting that they result from a direct effect of diabetes on the neural retina. In the course of diabetes there is a chronic loss of retinal neurons due to increased frequency of apoptosis. The neuronal apoptosis begins very early in the course of diabetes. This observation has led to suggestions that precautions against DR should be implemented immediately after diabetes is diagnosed. Neurodegeneration cannot be reversed; therefore treatments preventing neuronal cell loss in the retina need to be developed to protect diabetic patients. This review is an attempt to summarize what is currently known about the mechanisms of neuronal apoptosis in the context of diabetic retinopathy and vascular degeneration as well as about potential treatments of DR
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Affiliation(s)
| | | | | | - Katarzyna Zorena
- Department of Immunobiology and Environment Microbiology, Medical University of Gdańsk, Dębinki 7, 80-211 Gdańsk, Poland
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Nesan D, Kurrasch DM. Genetic programs of the developing tuberal hypothalamus and potential mechanisms of their disruption by environmental factors. Mol Cell Endocrinol 2016; 438:3-17. [PMID: 27720896 DOI: 10.1016/j.mce.2016.09.031] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 09/22/2016] [Accepted: 09/29/2016] [Indexed: 12/15/2022]
Abstract
The hypothalamus is a critical regulator of body homeostasis, influencing the autonomic nervous system and releasing trophic hormones to modulate the endocrine system. The developmental mechanisms that govern formation of the mature hypothalamus are becoming increasingly understood as research in this area grows, leading us to gain appreciation for how these developmental programs are susceptible to disruption by maternal exposure to endocrine disrupting chemicals or other environmental factors in utero. These vulnerabilities, combined with the prominent roles of the various hypothalamic nuclei in regulating appetite, reproductive behaviour, mood, and other physiologies, create a window whereby early developmental disruption can have potent long-term effects. Here we broadly outline our current understanding of hypothalamic development, with a particular focus on the tuberal hypothalamus, including what is know about nuclear coalescing and maturation. We finish by discussing how exposure to environmental or maternally-derived factors can perhaps disrupt these hypothalamic developmental programs, and potentially lead to neuroendocrine disease states.
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Affiliation(s)
- Dinushan Nesan
- Department of Medical Genetics, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Deborah M Kurrasch
- Department of Medical Genetics, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada.
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Orellana JA. Physiological Functions of Glial Cell Hemichannels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:93-108. [DOI: 10.1007/978-3-319-40764-7_5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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85
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Inhibition of hypothalamic MCT1 expression increases food intake and alters orexigenic and anorexigenic neuropeptide expression. Sci Rep 2016; 6:33606. [PMID: 27677351 PMCID: PMC5039692 DOI: 10.1038/srep33606] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/30/2016] [Indexed: 01/24/2023] Open
Abstract
Hypothalamic glucosensing, which involves the detection of glucose concentration changes by brain cells and subsequent release of orexigenic or anorexigenic neuropeptides, is a crucial process that regulates feeding behavior. Arcuate nucleus (AN) neurons are classically thought to be responsible for hypothalamic glucosensing through a direct sensing mechanism; however, recent data has shown a metabolic interaction between tanycytes and AN neurons through lactate that may also be contributing to this process. Monocarboxylate transporter 1 (MCT1) is the main isoform expressed by tanycytes, which could facilitate lactate release to hypothalamic AN neurons. We hypothesize that MCT1 inhibition could alter the metabolic coupling between tanycytes and AN neurons, altering feeding behavior. To test this, we inhibited MCT1 expression using adenovirus-mediated transfection of a shRNA into the third ventricle, transducing ependymal wall cells and tanycytes. Neuropeptide expression and feeding behavior were measured in MCT1-inhibited animals after intracerebroventricular glucose administration following a fasting period. Results showed a loss in glucose regulation of orexigenic neuropeptides and an abnormal expression of anorexigenic neuropeptides in response to fasting. This was accompanied by an increase in food intake and in body weight gain. Taken together, these results indicate that MCT1 expression in tanycytes plays a role in feeding behavior regulation.
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86
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Gajardo-Gómez R, Labra VC, Orellana JA. Connexins and Pannexins: New Insights into Microglial Functions and Dysfunctions. Front Mol Neurosci 2016; 9:86. [PMID: 27713688 PMCID: PMC5031785 DOI: 10.3389/fnmol.2016.00086] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/05/2016] [Indexed: 12/11/2022] Open
Abstract
Under physiological conditions, microglia adopt a resting phenotype associated with the production of anti-inflammatory and neurotrophic factors. In response to a wide variety of insults, these cells shift to an activated phenotype that is necessary for the proper restoration of brain homeostasis. However, when the intensity of a threat is relatively high, microglial activation worsens the progression of damage rather than providing protection, with potentially significant consequences for neuronal survival. Coordinated interactions among microglia and other brain cells, including astrocytes and neurons, are critical for the development of timely and optimal inflammatory responses in the brain parenchyma. Tissue synchronization is in part mediated by connexins and pannexins, which are protein families that form different plasma membrane channels to communicate with neighboring cells. Gap junction channels (which are exclusively formed by connexins in vertebrates) connect the cytoplasm of contacting cells to coordinate electrical and metabolic coupling. Hemichannels (HCs) and pannexons (which are formed by connexins and pannexins, respectively) communicate the intra- and extracellular compartments and serve as diffusion pathways for the exchange of ions and small molecules. In this review article, we discuss the available evidence concerning the functional expression and regulation of connexin- and pannexin-based channels in microglia and their contributions to microglial function and dysfunction. Specifically, we focus on the possible implications of these channels in microglia-to-microglia, microglia-to-astrocyte and neuron-to-microglia interactions in the inflamed brain.
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Affiliation(s)
- Rosario Gajardo-Gómez
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Valeria C Labra
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
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Wittmann G, Farkas E, Szilvásy-Szabó A, Gereben B, Fekete C, Lechan RM. Variable proopiomelanocortin expression in tanycytes of the adult rat hypothalamus and pituitary stalk. J Comp Neurol 2016; 525:411-441. [PMID: 27503597 DOI: 10.1002/cne.24090] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/01/2016] [Accepted: 08/04/2016] [Indexed: 01/21/2023]
Abstract
It is generally believed that proopiomelanocortin (POMC) is expressed exclusively by neurons in the adult rodent brain. Unbeknownst to most researchers, however, Pomc in situ hybridization studies in the rat show specific labeling in the ventral wall of the hypothalamic third ventricle, which is formed by specialized ependymal cells, called tanycytes. Here we characterized this non-neuronal POMC expression in detail using in situ hybridization and immunohistochemical techniques, and report two unique characteristics. First, POMC mRNA and precursor protein expression in non-neuronal cells varies to a great degree as to the extent and abundance of expression. In brains with low-level expression, POMC mRNA and protein was largely confined to a population of tanycytes within the infundibular stalk/caudal median eminence, termed here γ tanycytes, and a subset of closely located β and α2 tanycytes. In brains with high-level expression, POMC mRNA and protein was observed in the vast majority of α2, β, and γ tanycytes. This variability was observed in both adult males and females; of 41 rats between 8 and 15 weeks of age, 17 had low-, 9 intermediate-, and 15 high-level POMC expression in tanycytes. Second, unlike other known POMC-expressing cells, tanycytes rarely contained detectable levels of adrenocorticotropin or α-melanocyte-stimulating hormone. The results indicate either a dynamic spatiotemporal pattern whereby low and high POMC syntheses in tanycytes occur periodically in each brain, or marked interindividual differences that may persist throughout adulthood. Future studies are required to examine these possibilities and elucidate the physiologic importance of POMC in tanycytes. J. Comp. Neurol. 525:411-441, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Gábor Wittmann
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts, 02111
| | - Erzsébet Farkas
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, 1083, Hungary.,Pázmány Péter Catholic University, Multidisciplinary Doctoral School of Sciences and Technology, Budapest, 1083, Hungary
| | - Anett Szilvásy-Szabó
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, 1083, Hungary.,Semmelweis University, János Szentágothai PhD School of Neurosciences, Budapest, 1085, Hungary
| | - Balázs Gereben
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, 1083, Hungary
| | - Csaba Fekete
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts, 02111.,Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, 1083, Hungary
| | - Ronald M Lechan
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts, 02111.,Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts, 02111
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88
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Johnson RG, Le HC, Evenson K, Loberg SW, Myslajek TM, Prabhu A, Manley AM, O’Shea C, Grunenwald H, Haddican M, Fitzgerald PM, Robinson T, Cisterna BA, Sáez JC, Liu TF, Laird DW, Sheridan JD. Connexin Hemichannels: Methods for Dye Uptake and Leakage. J Membr Biol 2016; 249:713-741. [DOI: 10.1007/s00232-016-9925-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 08/22/2016] [Indexed: 01/18/2023]
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89
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Orellana JA, Retamal MA, Moraga-Amaro R, Stehberg J. Role of Astroglial Hemichannels and Pannexons in Memory and Neurodegenerative Diseases. Front Integr Neurosci 2016; 10:26. [PMID: 27489539 PMCID: PMC4951483 DOI: 10.3389/fnint.2016.00026] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 07/06/2016] [Indexed: 11/13/2022] Open
Abstract
Under physiological conditions, astroglial hemichannels and pannexons allow the release of gliotransmitters from astrocytes. These gliotransmitters are critical in modulating synaptic transmission, plasticity and memory. However, recent evidence suggests that under pathological conditions, they may be central in the development of various neurodegenerative diseases. Here we review current literature on the role of astroglial hemichannels and pannexons in memory, stress and the development of neurodegenerative diseases, and propose that they are not only crucial for normal brain function, including memory, but also a potential target for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo Santiago, Chile
| | - Rodrigo Moraga-Amaro
- Laboratorio de Neurobiología, Centro de Investigaciones Biomédicas, Universidad Andres Bello Santiago, Chile
| | - Jimmy Stehberg
- Laboratorio de Neurobiología, Centro de Investigaciones Biomédicas, Universidad Andres Bello Santiago, Chile
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90
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Scarlett JM, Rojas JM, Matsen ME, Kaiyala KJ, Stefanovski D, Bergman RN, Nguyen HT, Dorfman MD, Lantier L, Wasserman DH, Mirzadeh Z, Unterman TG, Morton GJ, Schwartz MW. Central injection of fibroblast growth factor 1 induces sustained remission of diabetic hyperglycemia in rodents. Nat Med 2016; 22:800-6. [PMID: 27213816 PMCID: PMC4938755 DOI: 10.1038/nm.4101] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 04/08/2016] [Indexed: 12/11/2022]
Abstract
Type 2 diabetes (T2D) is among the most common and costly disorders worldwide. The goal of current medical management for T2D is to transiently ameliorate hyperglycemia through daily dosing of one or more antidiabetic drugs. Hypoglycemia and weight gain are common side effects of therapy, and sustained disease remission is not obtainable with nonsurgical approaches. On the basis of the potent glucose-lowering response elicited by activation of brain fibroblast growth factor (FGF) receptors, we explored the antidiabetic efficacy of centrally administered FGF1, which, unlike other FGF peptides, activates all FGF receptor subtypes. We report that a single intracerebroventricular injection of FGF1 at a dose one-tenth of that needed for antidiabetic efficacy following peripheral injection induces sustained diabetes remission in both mouse and rat models of T2D. This antidiabetic effect is not secondary to weight loss, does not increase the risk of hypoglycemia, and involves a novel and incompletely understood mechanism for increasing glucose clearance from the bloodstream. We conclude that the brain has an inherent potential to induce diabetes remission and that brain FGF receptors are potential pharmacological targets for achieving this goal.
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MESH Headings
- Adipose Tissue/drug effects
- Adipose Tissue/metabolism
- Animals
- Blood Glucose/drug effects
- Blood Glucose/metabolism
- Blotting, Western
- Body Composition
- Brain/drug effects
- Brain/metabolism
- Carbon Radioisotopes
- Deoxyglucose
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 2/metabolism
- Diet, High-Fat
- Disease Models, Animal
- Ependymoglial Cells/drug effects
- Ependymoglial Cells/metabolism
- Fibroblast Growth Factor 1/pharmacology
- Forkhead Box Protein O1/genetics
- Glucose Tolerance Test
- Heart/drug effects
- Heat-Shock Proteins/drug effects
- Heat-Shock Proteins/metabolism
- Hyperglycemia/metabolism
- Hypothalamus/cytology
- Hypothalamus/drug effects
- Hypothalamus/metabolism
- Injections, Intraventricular
- Liver/metabolism
- Male
- Mice
- Mice, Knockout
- Mice, Obese
- Molecular Chaperones
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Myocardium/metabolism
- Neoplasm Proteins/drug effects
- Neoplasm Proteins/metabolism
- Proto-Oncogene Proteins c-fos/drug effects
- Proto-Oncogene Proteins c-fos/metabolism
- Rats
- Rats, Zucker
- Real-Time Polymerase Chain Reaction
- Receptor, Insulin/antagonists & inhibitors
- Receptor, Insulin/genetics
- Remission Induction
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Affiliation(s)
- Jarrad M Scarlett
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington, USA
- Department of Pediatric Gastroenterology and Hepatology, Seattle Children's Hospital, Seattle, Washington, USA
| | - Jennifer M Rojas
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Miles E Matsen
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Karl J Kaiyala
- Department of Oral Health Sciences, School of Dentistry, University of Washington, Seattle, Washington, USA
| | - Darko Stefanovski
- New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Richard N Bergman
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Hong T Nguyen
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Mauricio D Dorfman
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Louise Lantier
- Department of Molecular Physiology and Biophysics, Vanderbilt School of Medicine, Nashville, Tennessee, USA
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt School of Medicine, Nashville, Tennessee, USA
| | - Zaman Mirzadeh
- Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Terry G Unterman
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
- Medical Service, Jesse Brown Virginia Medical Center, Chicago, Illinois, USA
| | - Gregory J Morton
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Michael W Schwartz
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington, USA
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91
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Castellano P, Nwagbo C, Martinez LR, Eugenin EA. Methamphetamine compromises gap junctional communication in astrocytes and neurons. J Neurochem 2016; 137:561-75. [PMID: 26953131 DOI: 10.1111/jnc.13603] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 02/22/2016] [Accepted: 02/26/2016] [Indexed: 12/18/2022]
Abstract
Methamphetamine (meth) is a central nervous system (CNS) stimulant that results in psychological and physical dependency. The long-term effects of meth within the CNS include neuronal plasticity changes, blood-brain barrier compromise, inflammation, electrical dysfunction, neuronal/glial toxicity, and an increased risk to infectious diseases including HIV. Most of the reported meth effects in the CNS are related to dysregulation of chemical synapses by altering the release and uptake of neurotransmitters, especially dopamine, norepinephrine, and epinephrine. However, little is known about the effects of meth on connexin (Cx) containing channels, such as gap junctions (GJ) and hemichannels (HC). We examined the effects of meth on Cx expression, function, and its role in NeuroAIDS. We found that meth altered Cx expression and localization, decreased GJ communication between neurons and astrocytes, and induced the opening of Cx43/Cx36 HC. Furthermore, we found that these changes in GJ and HC induced by meth treatment were mediated by activation of dopamine receptors, suggesting that dysregulation of dopamine signaling induced by meth is essential for GJ and HC compromise. Meth-induced changes in GJ and HC contributed to amplified CNS toxicity by dysregulating glutamate metabolism and increasing the susceptibility of neurons and astrocytes to bystander apoptosis induced by HIV. Together, our results indicate that connexin containing channels, GJ and HC, are essential in the pathogenesis of meth and increase the sensitivity of the CNS to HIV CNS disease. Methamphetamine (meth) is an extremely addictive central nervous system stimulant. Meth reduced gap junctional (GJ) communication by inducing internalization of connexin-43 (Cx43) in astrocytes and reducing expression of Cx36 in neurons by a mechanism involving activation of dopamine receptors (see cartoon). Meth-induced changes in Cx containing channels increased extracellular levels of glutamate and resulted in higher sensitivity of neurons and astrocytes to apoptosis in response to HIV infection.
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Affiliation(s)
- Paul Castellano
- Public Health Research Institute (PHRI), New Jersey Medical School, Rutgers University, Newark, New Jersey, USA.,Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Chisom Nwagbo
- Public Health Research Institute (PHRI), New Jersey Medical School, Rutgers University, Newark, New Jersey, USA.,Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Luis R Martinez
- New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, USA
| | - Eliseo A Eugenin
- Public Health Research Institute (PHRI), New Jersey Medical School, Rutgers University, Newark, New Jersey, USA.,Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
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92
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Velasquez S, Malik S, Lutz SE, Scemes E, Eugenin EA. Pannexin1 Channels Are Required for Chemokine-Mediated Migration of CD4+ T Lymphocytes: Role in Inflammation and Experimental Autoimmune Encephalomyelitis. THE JOURNAL OF IMMUNOLOGY 2016; 196:4338-47. [PMID: 27076682 DOI: 10.4049/jimmunol.1502440] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 03/09/2016] [Indexed: 12/19/2022]
Abstract
Pannexin1 (Panx1) channels are large high conductance channels found in all vertebrates that can be activated under several physiological and pathological conditions. Our published data indicate that HIV infection results in the extended opening of Panx1 channels (5-60 min), allowing for the secretion of ATP through the channel pore with subsequent activation of purinergic receptors, which facilitates HIV entry and replication. In this article, we demonstrate that chemokines, which bind CCR5 and CXCR4, especially SDF-1α/CXCL12, result in a transient opening (peak at 5 min) of Panx1 channels found on CD4(+) T lymphocytes, which induces ATP secretion, focal adhesion kinase phosphorylation, cell polarization, and subsequent migration. Increased migration of immune cells is key for the pathogenesis of several inflammatory diseases including multiple sclerosis (MS). In this study, we show that genetic deletion of Panx1 reduces the number of the CD4(+) T lymphocytes migrating into the spinal cord of mice subjected to experimental autoimmune encephalomyelitis, an animal model of MS. Our results indicate that opening of Panx1 channels in response to chemokines is required for CD4(+) T lymphocyte migration, and we propose that targeting Panx1 channels could provide new potential therapeutic approaches to decrease the devastating effects of MS and other inflammatory diseases.
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Affiliation(s)
- Stephani Velasquez
- Public Health Research Institute, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103; Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103
| | - Shaily Malik
- Public Health Research Institute, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103; Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103
| | - Sarah E Lutz
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA 92697; and
| | - Eliana Scemes
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Eliseo A Eugenin
- Public Health Research Institute, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103; Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103;
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93
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Pollatzek E, Hitzel N, Ott D, Raisl K, Reuter B, Gerstberger R. Functional expression of P2 purinoceptors in a primary neuroglial cell culture of the rat arcuate nucleus. Neuroscience 2016; 327:95-114. [PMID: 27072848 DOI: 10.1016/j.neuroscience.2016.04.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 04/06/2016] [Accepted: 04/06/2016] [Indexed: 12/22/2022]
Abstract
The arcuate nucleus (ARC) plays an important role in the hypothalamic control of energy homeostasis. Expression of various purinoceptor subtypes in the rat ARC and physiological studies suggest a modulatory function of P2 receptors within the neuroglial ARC circuitry. A differentiated mixed neuronal and glial microculture was therefore established from postnatal rat ARC, revealing neuronal expression of ARC-specific transmitters involved in food intake regulation (neuropeptide Y (NPY), proopiomelanocortin (POMC), tyrosine hydroxylase (TH)). Some NPYergic neurons cosynthesized TH, while POMC and TH expression proved to be mutually exclusive. Stimulation with the general purinoceptor agonists 2-methylthioadenosine-5'triphosphate (2-MeSATP) and ATP but not the P2X1/P2X3 receptor subtype agonist α,β-methyleneadenosine-5'triphosphate (α,β-meATP) induced intracellular calcium signals in ARC neurons and astrocytes. Some 5-10% each of 2-MeSATP responsive neurons expressed POMC, NYP or TH. Supporting the calcium imaging data, radioligand binding studies to hypothalamic membranes showed high affinity for 2-MeSATP, ATP but not α,β-meATP to displace [α-(35)S]deoxyadenosine-5'thiotriphosphate ([(35)S]dATPαS) from P2 receptors. Repetitive superfusion with equimolar 2-MeSATP allowed categorization of ARC cells into groups with a high or low (LDD) degree of purinoceptor desensitization, the latter allowing further receptor characterization. Calcium imaging experiments performed at 37°C vs. room temperature showed further reduction of desensitization. Agonist-mediated intracellular calcium signals were suppressed in all LDD neurons but only 25% of astrocytes in the absence of extracellular calcium, suggestive of metabotropic P2Y receptor expression in the majority of ARC astrocytes. The highly P2Y1-selective receptor agonists MRS2365 and 2-methylthioadenosine-5'diphosphate (2-MeSADP) activated 75-85% of all 2-MeSATP-responsive ARC astrocytes. Taking into consideration the high potency to dose-dependently stimulate ARC cells of the LDD group, the high affinity for rat P2X(1-3) and low affinity for rat P2X4, P2X7 and P2Y receptor subtypes except P2Y1 and P2Y13, the agonist 2-MeSATP primarily acted upon P2X2 and P2Y1 purinoceptors to trigger intracellular calcium signaling in ARC neurons and astrocytes.
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Affiliation(s)
- Eric Pollatzek
- Institut für Veterinär-Physiologie und -Biochemie, Justus-Liebig-Universität Giessen, Frankfurter Strasse 100, D-35392 Giessen, Deutschland.
| | - Norma Hitzel
- Institut für Veterinär-Physiologie und -Biochemie, Justus-Liebig-Universität Giessen, Frankfurter Strasse 100, D-35392 Giessen, Deutschland.
| | - Daniela Ott
- Institut für Veterinär-Physiologie und -Biochemie, Justus-Liebig-Universität Giessen, Frankfurter Strasse 100, D-35392 Giessen, Deutschland.
| | - Katrin Raisl
- Institut für Veterinär-Physiologie und -Biochemie, Justus-Liebig-Universität Giessen, Frankfurter Strasse 100, D-35392 Giessen, Deutschland.
| | - Bärbel Reuter
- Institut für Veterinär-Physiologie und -Biochemie, Justus-Liebig-Universität Giessen, Frankfurter Strasse 100, D-35392 Giessen, Deutschland.
| | - Rüdiger Gerstberger
- Institut für Veterinär-Physiologie und -Biochemie, Justus-Liebig-Universität Giessen, Frankfurter Strasse 100, D-35392 Giessen, Deutschland.
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94
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Osteocytic connexin hemichannels suppress breast cancer growth and bone metastasis. Oncogene 2016; 35:5597-5607. [PMID: 27041582 PMCID: PMC5050050 DOI: 10.1038/onc.2016.101] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 01/13/2016] [Accepted: 01/25/2016] [Indexed: 12/15/2022]
Abstract
Although the skeleton is one of predominant sites for breast cancer metastasis, why breast cancer cells often become dormant after homing to bone is not well understood. Here, we reported an intrinsic self-defense mechanism of bone cells against breast cancer cells: a critical role of connexin (Cx) 43 hemichannels in osteocytes in the suppression of breast cancer bone metastasis. Cx43 hemichannels allow passage of small molecules between the intracellular and extracellular environments. The treatment of bisphosphonate drugs, either alendronate (ALN) or zoledronic acid (ZOL), opened Cx43 hemichannels in osteocytes. Conditioned media (CM) collected from MLO-Y4 osteocyte cells treated with bisphosphonates inhibited the anchorage-independent growth, migration and invasion of MDA-MB-231 human breast cancer cells and Py8119 mouse mammary carcinoma cells and this inhibitory effect was attenuated with Cx43(E2), a specific hemichannel blocking antibody. The opening of osteocytic Cx43 hemichannels by mechanical stimulation had similar inhibitory effects on breast cancer cells and this inhibition was attenuated by Cx43(E2) antibody as well. These inhibitory effects on cancer cells were mediated by ATP released from osteocyte Cx43 hemichannels. Furthermore, both Cx43 osteocyte-specific knockout mice and osteocyte-specific Δ130–136 transgenic mice with impaired Cx43 gap junctions and hemichannels showed significantly increased tumor growth and attenuated the inhibitory effect of ZOL. However, R76W transgenic mice with functional hemichannels but not gap junctions in osteocytes did not display a significant difference. Together, our studies establish the specific inhibitory role of osteocytic Cx43 hemichannels, and exploiting the activity of this channel could serve as a de novo therapeutic strategy.
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95
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Puebla C, Cisterna BA, Salas DP, Delgado-López F, Lampe PD, Sáez JC. Linoleic acid permeabilizes gastric epithelial cells by increasing connexin 43 levels in the cell membrane via a GPR40- and Akt-dependent mechanism. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:439-48. [PMID: 26869446 DOI: 10.1016/j.bbalip.2016.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 01/25/2016] [Accepted: 02/06/2016] [Indexed: 02/08/2023]
Abstract
Linoleic acid (LA) is known to activate G-protein coupled receptors and connexin hemichannels (Cx HCs) but possible interlinks between these two responses remain unexplored. Here, we evaluated the mechanism of action of LA on the membrane permeability mediated by Cx HCs in MKN28 cells. These cells were found to express connexins, GPR40, GPR120, and CD36 receptors. The Cx HC activity of these cells increased after 5 min of treatment with LA or GW9508, an agonist of GPR40/GPR120; or exposure to extracellular divalent cation-free solution (DCFS), known to increase the open probability of Cx HCs, yields an immediate increase in Cx HC activity of similar intensity and additive with LA-induced change. Treatment with a CD36 blocker or transfection with siRNA-GPR120 maintains the LA-induced Cx HC activity. However, cells transfected with siRNA-GPR40 did not show LA-induced Cx HC activity but activity was increased upon exposure to DCFS, confirming the presence of activatable Cx HCs in the cell membrane. Treatment with AKTi (Akt inhibitor) abrogated the LA-induced Cx HC activity. In HeLa cells transfected with Cx43 (HeLa-Cx43), LA induced phosphorylation of surface Cx43 at serine 373 (S373), site for Akt phosphorylation. HeLa-Cx43 but not HeLa-Cx43 cells with a S373A mutation showed a LA-induced Cx HC activity directly related to an increase in cell surface Cx43 levels. Thus, the increase in membrane permeability induced by LA is mediated by an intracellular signaling pathway activated by GPR40 that leads to an increase in membrane levels of Cx43 phosphorylated at serine 373 via Akt.
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Affiliation(s)
- Carlos Puebla
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | - Bruno A Cisterna
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Daniela P Salas
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Fernando Delgado-López
- Laboratorios de Biomedicina, Departamento de Ciencias Preclínicas, Facultad de Medicina, Universidad Católica del Maule, Talca, Chile
| | - Paul D Lampe
- Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States
| | - Juan C Sáez
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile.
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96
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Pinet-Charvet C, Geller S, Desroziers E, Ottogalli M, Lomet D, Georgelin C, Tillet Y, Franceschini I, Vaudin P, Duittoz A. GnRH Episodic Secretion Is Altered by Pharmacological Blockade of Gap Junctions: Possible Involvement of Glial Cells. Endocrinology 2016; 157:304-22. [PMID: 26562259 DOI: 10.1210/en.2015-1437] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Episodic release of GnRH is essential for reproductive function. In vitro studies have established that this episodic release is an endogenous property of GnRH neurons and that GnRH secretory pulses are associated with synchronization of GnRH neuron activity. The cellular mechanisms by which GnRH neurons synchronize remain largely unknown. There is no clear evidence of physical coupling of GnRH neurons through gap junctions to explain episodic synchronization. However, coupling of glial cells through gap junctions has been shown to regulate neuron activity in their microenvironment. The present study investigated whether glial cell communication through gap junctions plays a role in GnRH neuron activity and secretion in the mouse. Our findings show that Glial Fibrillary Acidic Protein-expressing glial cells located in the median eminence in close vicinity to GnRH fibers expressed Gja1 encoding connexin-43. To study the impact of glial-gap junction coupling on GnRH neuron activity, an in vitro model of primary cultures from mouse embryo nasal placodes was used. In this model, GnRH neurons possess a glial microenvironment and were able to release GnRH in an episodic manner. Our findings show that in vitro glial cells forming the microenvironment of GnRH neurons expressed connexin-43 and displayed functional gap junctions. Pharmacological blockade of the gap junctions with 50 μM 18-α-glycyrrhetinic acid decreased GnRH secretion by reducing pulse frequency and amplitude, suppressed neuronal synchronization and drastically reduced spontaneous electrical activity, all these effects were reversed upon 18-α-glycyrrhetinic acid washout.
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Affiliation(s)
- Caroline Pinet-Charvet
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Sarah Geller
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Elodie Desroziers
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Monique Ottogalli
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Didier Lomet
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Christine Georgelin
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Yves Tillet
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Isabelle Franceschini
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Pascal Vaudin
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Anne Duittoz
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
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97
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Del Rio R, Quintanilla RA, Orellana JA, Retamal MA. Neuron-Glia Crosstalk in the Autonomic Nervous System and Its Possible Role in the Progression of Metabolic Syndrome: A New Hypothesis. Front Physiol 2015; 6:350. [PMID: 26648871 PMCID: PMC4664731 DOI: 10.3389/fphys.2015.00350] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 11/09/2015] [Indexed: 01/26/2023] Open
Abstract
Metabolic syndrome (MS) is characterized by the following physiological alterations: increase in abdominal fat, insulin resistance, high concentration of triglycerides, low levels of HDL, high blood pressure, and a generalized inflammatory state. One of the pathophysiological hallmarks of this syndrome is the presence of neurohumoral activation, which involve autonomic imbalance associated to hyperactivation of the sympathetic nervous system. Indeed, enhanced sympathetic drive has been linked to the development of endothelial dysfunction, hypertension, stroke, myocardial infarct, and obstructive sleep apnea. Glial cells, the most abundant cells in the central nervous system, control synaptic transmission, and regulate neuronal function by releasing bioactive molecules called gliotransmitters. Recently, a new family of plasma membrane channels called hemichannels has been described to allow the release of gliotransmitters and modulate neuronal firing rate. Moreover, a growing amount of evidence indicates that uncontrolled hemichannel opening could impair glial cell functions, affecting synaptic transmission and neuronal survival. Given that glial cell functions are disturbed in various metabolic diseases, we hypothesize that progression of MS may relies on hemichannel-dependent impairment of glial-to-neuron communication by a mechanism related to dysfunction of inflammatory response and mitochondrial metabolism of glial cells. In this manuscript, we discuss how glial cells may contribute to the enhanced sympathetic drive observed in MS, and shed light about the possible role of hemichannels in this process.
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Affiliation(s)
- Rodrigo Del Rio
- Centro de Investigación Biomédica, Universidad Autónoma de Chile Santiago, Chile ; Dirección de Investigación, Universidad Científica del Sur Lima, Perú
| | | | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina. Clínica Alemana Universidad del Desarrollo Santiago, Chile
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98
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Steinbusch L, Labouèbe G, Thorens B. Brain glucose sensing in homeostatic and hedonic regulation. Trends Endocrinol Metab 2015; 26:455-66. [PMID: 26163755 DOI: 10.1016/j.tem.2015.06.005] [Citation(s) in RCA: 57] [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: 04/15/2015] [Revised: 06/15/2015] [Accepted: 06/16/2015] [Indexed: 11/21/2022]
Abstract
Glucose homeostasis as well as homeostatic and hedonic control of feeding is regulated by hormonal, neuronal, and nutrient-related cues. Glucose, besides its role as a source of metabolic energy, is an important signal controlling hormone secretion and neuronal activity, hence contributing to whole-body metabolic integration in coordination with feeding control. Brain glucose sensing plays a key, but insufficiently explored, role in these metabolic and behavioral controls, which when deregulated may contribute to the development of obesity and diabetes. The recent introduction of innovative transgenic, pharmacogenetic, and optogenetic techniques allows unprecedented analysis of the complexity of central glucose sensing at the molecular, cellular, and neuronal circuit levels, which will lead to a new understanding of the pathogenesis of metabolic diseases.
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Affiliation(s)
- Laura Steinbusch
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Gwenaël Labouèbe
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Bernard Thorens
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.
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99
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Activity-Dependent Plasticity of Astroglial Potassium and Glutamate Clearance. Neural Plast 2015; 2015:109106. [PMID: 26346563 PMCID: PMC4539499 DOI: 10.1155/2015/109106] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/17/2015] [Indexed: 12/21/2022] Open
Abstract
Recent evidence has shown that astrocytes play essential roles in synaptic transmission and plasticity. Nevertheless, how neuronal activity alters astroglial functional properties and whether such properties also display specific forms of plasticity still remain elusive. Here, we review research findings supporting this aspect of astrocytes, focusing on their roles in the clearance of extracellular potassium and glutamate, two neuroactive substances promptly released during excitatory synaptic transmission. Their subsequent removal, which is primarily carried out by glial potassium channels and glutamate transporters, is essential for proper functioning of the brain. Similar to neurons, different forms of short- and long-term plasticity in astroglial uptake have been reported. In addition, we also present novel findings showing robust potentiation of astrocytic inward currents in response to repetitive stimulations at mild frequencies, as low as 0.75 Hz, in acute hippocampal slices. Interestingly, neurotransmission was hardly affected at this frequency range, suggesting that astrocytes may be more sensitive to low frequency stimulation and may exhibit stronger plasticity than neurons to prevent hyperexcitability. Taken together, these important findings strongly indicate that astrocytes display both short- and long-term plasticity in their clearance of excess neuroactive substances from the extracellular space, thereby regulating neuronal activity and brain homeostasis.
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100
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Decrock E, De Bock M, Wang N, Bultynck G, Giaume C, Naus CC, Green CR, Leybaert L. Connexin and pannexin signaling pathways, an architectural blueprint for CNS physiology and pathology? Cell Mol Life Sci 2015; 72:2823-51. [PMID: 26118660 PMCID: PMC11113968 DOI: 10.1007/s00018-015-1962-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 02/06/2023]
Abstract
The central nervous system (CNS) is composed of a highly heterogeneous population of cells. Dynamic interactions between different compartments (neuronal, glial, and vascular systems) drive CNS function and allow to integrate and process information as well as to respond accordingly. Communication within this functional unit, coined the neuro-glio-vascular unit (NGVU), typically relies on two main mechanisms: direct cell-cell coupling via gap junction channels (GJCs) and paracrine communication via the extracellular compartment, two routes to which channels composed of transmembrane connexin (Cx) or pannexin (Panx) proteins can contribute. Multiple isoforms of both protein families are present in the CNS and each CNS cell type is characterized by a unique Cx/Panx portfolio. Over the last two decades, research has uncovered a multilevel platform via which Cxs and Panxs can influence different cellular functions within a tissue: (1) Cx GJCs enable a direct cell-cell communication of small molecules, (2) Cx hemichannels and Panx channels can contribute to autocrine/paracrine signaling pathways, and (3) different structural domains of these proteins allow for channel-independent functions, such as cell-cell adhesion, interactions with the cytoskeleton, and the activation of intracellular signaling pathways. In this paper, we discuss current knowledge on their multifaceted contribution to brain development and to specific processes in the NGVU, including synaptic transmission and plasticity, glial signaling, vasomotor control, and blood-brain barrier integrity in the mature CNS. By highlighting both physiological and pathological conditions, it becomes evident that Cxs and Panxs can play a dual role in the CNS and that an accurate fine-tuning of each signaling mechanism is crucial for normal CNS physiology.
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Affiliation(s)
- Elke Decrock
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Marijke De Bock
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Nan Wang
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Louvain, Belgium
| | - Christian Giaume
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, 75231 Paris Cedex 05, France
- University Pierre et Marie
Curie, ED, N°158, 75005 Paris, France
- MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005 Paris, France
| | - Christian C. Naus
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3 Canada
| | - Colin R. Green
- Department of Ophthalmology, The University of Auckland, Auckland, New Zealand
| | - Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
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