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Title

The rate-limiting step for glucose transport into the hypothalamus is across the blood-hypothalamus interface

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Published in Journal of Neurochemistry. 2009, vol. 109 Suppl 1, p. 38-45
Abstract Specialized glucosensing neurons are present in the hypothalamus, some of which neighbor the median eminence, where the blood-brain barrier has been reported leaky. A leaky blood-brain barrier implies high tissue glucose levels and obviates a role for endothelial glucose transporters in the control of hypothalamic glucose concentration, important in understanding the mechanisms of glucose sensing We therefore addressed the question of blood-brain barrier integrity at the hypothalamus for glucose transport by examining the brain tissue-to-plasma glucose ratio in the hypothalamus relative to other brain regions. We also examined glycogenolysis in hypothalamus because its occurrence is unlikely in the potential absence of a hypothalamus-blood interface. Across all regions the concentration of glucose was comparable at a given plasma glucose concentration and was a near linear function of plasma glucose. At steady-state, hypothalamic glucose concentration was similar to the extracellular hypothalamic glucose concentration reported by others. Hypothalamic glycogen fell at a rate of approximately 1.5 micromol/g/h and remained present in substantial amounts. We conclude for the hypothalamus, a putative primary site of brain glucose sensing that: the rate-limiting step for glucose transport into brain cells is at the blood-hypothalamus interface, and that glycogenolysis is consistent with a substantial blood -to- intracellular glucose concentration gradient.
Keywords AlgorithmsAnimalsBiological Transport, Active/physiologyBlood Glucose/metabolismBlood-Brain Barrier/physiologyBrain/anatomy & histologyBrain Chemistry/physiologyGlucose/metabolismGlucose Transporter Type 1/metabolismGlycogen/metabolismHypothalamus/metabolismKineticsLiver Glycogen/metabolismMaleMicrowavesRatsRats, Sprague-DawleyReproducibility of ResultsTissue Fixation
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PMID: 19393007
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Research group CIBM (863)
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POITRY-YAMATE, Carole, LEI, Hongxia, GRUETTER, Rolf. The rate-limiting step for glucose transport into the hypothalamus is across the blood-hypothalamus interface. In: Journal of Neurochemistry, 2009, vol. 109 Suppl 1, p. 38-45. https://archive-ouverte.unige.ch/unige:32959

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Deposited on : 2014-01-08

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