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1 Laboratorio de Fisioloxia Animal, Universidade de Vigo, Vigo, Pontevedra, Spain
2 Department of Biology, University of Ottawa, Ottawa,, Canada
* To whom correspondence should be addressed. E-mail: jsoengas{at}uvigo.es.
The aim of this study was to evaluate the existence of a glucosensor in different regions of the brain and in the Brockmann bodies (BB) of the rainbow trout, Oncorhynchus mykiss. Five groups (n = 12) of trout were injected intraperitoneally with saline alone (control) or saline containing bovine glucagon (100 µg.kg-1), bovine insulin (4 mg.kg-1), 2-deoxy-D-glucose (100 mg.kg-1) or D-glucose (500 mg.kg-1) to promote hyperglycemia (glucagon, D-glucose, 2-deoxy-D-glucose) or hypoglycemia (insulin). Six hours following injection, samples from four brain regions (hypothalamus, telencephalon, hindbrain and midbrain) and the entire BB were taken. Our results demonstrate within the BB and both the hypothalamus and hindbrain a metabolic response different to that observed in other tissues (midbrain, telencephalon) but similar to that described in tissues known to be glucosensors in mammals. The metabolic responses of these areas to changes in plasma glycemia were characterized by parallel changes in GLUT-2 expression, hexokinase IV or glucokinase activity and expression, glycolytic potential, and levels of glycogen and glucose. These changes are similar to those reported in mammalian pancreatic 
-cells and glucose-excited (GE) neurons, two cell types containing glucosensors. This study provides evidence for the presence of glucosensors responsive to hyper- and hypoglycemia in rainbow trout BB, hypothalamus and hindbrain.
This article has been cited by other articles:
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  S. Polakof, S. Panserat, E. Plagnes-Juan, and J. L. Soengas Altered dietary carbohydrates significantly affect gene expression of the major glucosensing components in Brockmann bodies and hypothalamus of rainbow trout Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2008; 295(4): R1077 - R1088. [Abstract] [Full Text] [PDF]
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S. Polakof, J. M. Miguez, and J. L. Soengas Dietary carbohydrates induce changes in glucosensing capacity and food intake of rainbow trout Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2008; 295(2): R478 - R489. [Abstract] [Full Text] [PDF]
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S. Polakof, J. M. Miguez, and J. L. Soengas In vitro evidences for glucosensing capacity and mechanisms in hypothalamus, hindbrain, and Brockmann bodies of rainbow trout Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2007; 293(3): R1410 - R1420. [Abstract] [Full Text] [PDF]
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