| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
COMPARATIVE AND EVOLUTIONARY PHYSIOLOGY
1Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, Vigo, Spain; and 2Department of Biology and Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, Ontario, Canada
Submitted 15 February 2006 ; accepted in final form 7 April 2006
The expression and activities of glucokinase (GK) and hexokinase (HK) were assessed in different tissues of rainbow trout (Oncorhynchus mykiss) under different feeding conditions (fed, fasted for 14 days, and refed for 7 days). Two different HK-I cDNAs were identified with different tissue distributions. One transcript named heart or H-HK-I was observed in the four brain regions assessed, white muscle, kidney, and gills but not in liver or erythrocytes. A second transcript named liver or L-HK-I was found in all tissues surveyed. GK mRNA was identified only in liver and the four brain regions. GK expression was altered by feeding conditions, especially in liver and hypothalamus where food deprivation decreased and re-feeding increased expression; changes in expression reflected activity changes and changes in tissue glycogen levels. In contrast, feeding conditions did not alter expression of either HK-I transcript but did alter tissue HK activities. The reduced phosphorylating capacity noted with food deprivation correlates primarily with changes in tissue HK, whereas increased capacity, as with refeeding, was associated with changes in GK; these changes fit with the different Km values of the GK and HK enzymes. These results provide evidence for the hypothalamus acting as a glucosensor in trout, as hyperglycemia produced increased GK expression and activity, as well as increased glycogen levels. Thus, even though trout use glucose poorly, none of the parameters tested here relate to this inability to use glucose and suggest that, at least, rainbow trout, if given an appropriate carbohydrate diet, could metabolically adjust to such a diet.
feeding; glucosensing; brain; liver; glucose use
This article has been cited by other articles:
|
|
 |
|
  R. E. Drew, K. J. Rodnick, M. Settles, J. Wacyk, E. Churchill, M. S. Powell, R. W. Hardy, G. K. Murdoch, R. A. Hill, and B. D. Robison Effect of starvation on transcriptomes of brain and liver in adult female zebrafish (Danio rerio) Physiol Genomics, November 12, 2008; 35(3): 283 - 295. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. A. Clow, K. V. Ewart, and W. R. Driedzic Low temperature directly activates the initial glycerol antifreeze response in isolated rainbow smelt (Osmerus mordax) liver cells Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2008; 295(3): R961 - R970. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
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]
|
|
|
|
|
|
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]
|
|
|
|
|
|
S. Polakof, J. M. Miguez, T. W. Moon, and J. L. Soengas Evidence for the presence of a glucosensor in hypothalamus, hindbrain, and Brockmann bodies of rainbow trout Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2007; 292(4): R1657 - R1666. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
