Glucose increases intracellular free Ca(2+) in tanycytes via ATP released through connexin 43 hemichannels.
Glia
; 60(1): 53-68, 2012 Jan.
Article
en En
| MEDLINE
| ID: mdl-21987367
ABSTRACT
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(+) (K(ATP) ) channels, suggesting their involvement in hypothalamic glucosensing. Here, the transduction mechanism involved in the glucose-induced rise of intracellular free Ca(2+) concentration ([Ca(2+) ](i) ) in cultured ß-tanycytes was examined. Fura-2AM time-lapse fluorescence images revealed that glucose increases the intracellular Ca(2+) 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 K(ATP) channel-dependent pathway. Consequently, ATP export to the extracellular milieu was enhanced, resulting in activation of purinergic P2Y(1) receptors followed by inositol trisphosphate receptor activation and Ca(2+) release from intracellular stores. The present study identifies the mechanism by which glucose increases [Ca(2+) ](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.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Adenosina Trifosfato
/
Neuroglía
/
Calcio
/
Conexina 43
/
Glucosa
/
Líquido Intracelular
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Glia
Asunto de la revista:
NEUROLOGIA
Año:
2012
Tipo del documento:
Article
País de afiliación:
Chile