title: Hypothalamic ependymal-glial cells express the glucose transporter GLUT2, a protein involved in glucose sensing.
abstract: The GLUT2 glucose transporter and the K-ATP-sensitive potassium channels have been implicated as an integral part of the glucose-sensing mechanism in the pancreatic islet beta cells. The expression of GLUT2 and K-ATP channels in the hypothalamic region suggest that they are also involved in a sensing mechanism in this area. The hypothalamic glial cells, known as tanycytes alpha and beta, are specialized ependymal cells that bridge the cerebrospinal fluid and the portal blood of the median eminence. We used immunocytochemistry, in situ hybridization and transport analyses to demonstrate the glucose transporters expressed in tanycytes. Confocal microscopy using specific antibodies against GLUT1 and GLUT2 indicated that both transporters are expressed in alpha and beta tanycytes. In addition, primary cultures of mouse hypothalamic tanycytes were found to express both GLUT1 and GLUT2 transporters. Transport studies, including 2-deoxy-glucose and fructose uptake in the presence or absence of inhibitors, indicated that these transporters are functional in cultured tanycytes. Finally, our analyses indicated that tanycytes express the K-ATP channel subunit Kir6.1 in vitro. As the expression of GLUT2 and K-ATP channel is linked to glucose-sensing mechanisms in pancreatic beta cells, we postulate that tanycytes may be responsible, at least in part, for a mechanism that allows the hypothalamus to detect changes in glucose concentrations.
authors.affiliation: Departamento de Biología Molecular, Departamento de Histología y Embriología, Universidad de Concepción, Chile.
authors.forename: María  Angeles
authors.initials: M
authors.lastname: García
authors.forename: Carola
authors.initials: C
authors.lastname: Millán
authors.forename: Carolina
authors.initials: C
authors.lastname: Balmaceda-Aguilera
authors.forename: Tamara
authors.initials: T
authors.lastname: Castro
authors.forename: Patricia
authors.initials: P
authors.lastname: Pastor
authors.forename: Hernán
authors.initials: H
authors.lastname: Montecinos
authors.forename: Karin
authors.initials: K
authors.lastname: Reinicke
authors.forename: Felipe
authors.initials: F
authors.lastname: Zúñiga
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Vera
authors.forename: Sergio A
authors.initials: SA
authors.lastname: Oñate
authors.forename: Francisco
authors.initials: F
authors.lastname: Nualart
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004805:Ependyma / Q000166:cytology / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1; D051273:Glucose Transporter Type 2; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D008810:Mice, Inbred C57BL; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying / Q000096:biosynthesis
chemical_list: D051272:Glucose Transporter Type 1; D051273:Glucose Transporter Type 2; D009004:Monosaccharide Transport Proteins; D024661:Potassium Channels, Inwardly Rectifying; C495678:Slc2a1 protein, mouse; D005947:Glucose