Journal of Comparative Physiology B

, Volume 170, Issue 3, pp 237–243 | Cite as

Uptake of 3-O-methyl-D-[U-14C]glucose into brain of rainbow trout: possible effects of melatonin

  • M. Aldegunde
  • M. D. Andrés
  • J. L. Soengas
ORIGINAL PAPER

Abstract

The influx of glucose into the brain and plasma glucose disappearance were estimated in rainbow trout (Oncorhynchus mykiss) intravenously injected (1 ml · kg−1 body weight) with a single dose (15 μCi · kg−1 body weight) of 3-O-methyl-D-[U-14C]glucose ([U-14C]-3-OMG) at different times (2–160 min), and after intravenous injection at 15 min of increased doses (10–60 μCi · kg−1 body weight) of [U-14C]-3-OMG. Brain and plasma radiotracer concentrations were measured, and several kinetic parameters were calculated. The apparent brain glucose influx showed a maximum after 15–20 min of injection then decreased to a plateau after 80 min. Brain distribution space of 3-OMG increased from 2 min to 20 min reaching equilibrium from that time onwards at a value of 0.14 ml · g−1. The unidirectional clearance of glucose from blood to brain (k1) and the fractional clearance of glucose from brain to blood (k2) were estimated to be 0.093 ml · min−1 · g−1, and 0.867 min−1, respectively. A linear increase was observed in brain and plasma radiotracer concentrations when increased doses of [U-14C]-3-OMG were used. All these findings support a facilitative transport of glucose through the blood-brain barrier of rainbow trout with characteristics similar to those observed in mammals. The injection of different doses of melatonin (0.25–1.0 mg · kg−1) significantly increased brain glucose influx suggesting a possible role for melatonin in the regulation of glucose transport into the brain.

Key words Brain Glucose transport Melatonin Oncorhynchus mykiss Rainbow trout 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • M. Aldegunde
    • 1
  • M. D. Andrés
    • 1
  • J. L. Soengas
    • 2
  1. 1.Laboratorio de Fisioloxía Animal (Departamento de Fisioloxía), Facultade de Bioloxía, Universidade de Santiago de Compostela, 15706 Santiago de Compostela, Spain e-mail: fsaldegu@usc.es Tel.: + 34-981-563100, ext. 13335; Fax: + 34-981-596904ES
  2. 2.Laboratorio de Fisioloxía Animal, Facultade de Ciencias, Universidade de Vigo, SpainES

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