Glucose increases intracellular free Ca2+ in tanycytes via ATP released through connexin 43 hemichannels

The ventromedial hypothalamus is involved in regulating feeding and satiety behavior, and its neurons interact with specialized ependymal‐glial cells, termed tanycytes. The latter express glucose‐sensing proteins, including glucose transporter 2, glucokinase, and ATP‐sensitive K+ (KATP) channels, su...

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Bibliographic Details
Published in:Glia 2012-01, Vol.60 (1), p.53-68
Main Authors: Orellana, Juan A., Sáez, Pablo J., Cortés-campos, Christian, Elizondo, Roberto J., Shoji, Kenji F., Contreras-Duarte, Susana, Figueroa, Vania, Velarde, Victoria, Jiang, Jean X., Nualart, Francisco, Sáez, Juan C., García, María A.
Format: Article
Language:English
Subjects:
ATP
Calcium (intracellular)
Connexin 43
connexons
Feeding
Feeding behavior
Fluorescence
Glucokinase
Glucose
Glucose metabolism
Glucose transporter
glucosensing
Glycolysis
Hypothalamus
Hypothalamus (ventromedial)
Inositol 1,4,5-trisphosphate receptors
Neurons
Purine P2Y receptors
Receptor mechanisms
Satiety
tanycytes
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Summary:The ventromedial hypothalamus is involved in regulating feeding and satiety behavior, and its neurons interact with specialized ependymal‐glial cells, termed tanycytes. The latter express glucose‐sensing proteins, including glucose transporter 2, glucokinase, and ATP‐sensitive K+ (KATP) channels, suggesting their involvement in hypothalamic glucosensing. Here, the transduction mechanism involved in the glucose‐induced rise of intracellular free Ca2+ concentration ([Ca2+]i) in cultured β‐tanycytes was examined. Fura‐2AM time‐lapse fluorescence images revealed that glucose increases the intracellular Ca2+ signal in a concentration‐dependent manner. Glucose transportation, primarily via glucose transporters, and metabolism via anaerobic glycolysis increased connexin 43 (Cx43) hemichannel activity, evaluated by ethidium uptake and whole cell patch clamp recordings, through a KATP channel‐dependent pathway. Consequently, ATP export to the extracellular milieu was enhanced, resulting in activation of purinergic P2Y1 receptors followed by inositol trisphosphate receptor activation and Ca2+ release from intracellular stores. The present study identifies the mechanism by which glucose increases [Ca2+]i in tanycytes. It also establishes that Cx43 hemichannels can be rapidly activated under physiological conditions by the sequential activation of glucosensing proteins in normal tanycytes. © 2011 Wiley Periodicals, Inc.
ISSN:0894-1491
1098-1136
1098-1136
DOI:10.1002/glia.21246