Hepatic glucokinase and glucose-6-phosphatase responses to dietary glucose and starch in gilthead sea bream (Sparus aurata) juveniles reared at two temperatures

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Enes, P (Author) FCUP; Panserat, S (Author) Other; Kaushik, S (Author) Other; Oliva Teles, A (Author) FCUP

Journal

Title: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology

Vol. 149

Pages: 80-86

ISSN: 1095-6433

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 98 Citations

Scopus - 106 Citations

Scientific classification

FOS: Medical and Health sciences > Basic medicine

Other information

Authenticus ID: P-004-2VG

DOI: 10.1016/j.cbpa.2007.10.012

Abstract (EN): The effects of carbohydrate sources/complexity and rearing temperature on hepatic glucokinase (GK) and glucose-6-phosphatase (G6Pase) activities and gene expression were studied in gilthead sea bream juveniles. Two isonitrogenous (50% crude protein) and isolipidic (19% crude lipids) diets were formulated to contain 20% waxy maize starch or 20% glucose. Triplicate groups of fish (63.5 g initial body weight) were fed each diet to near satiation during four weeks at 18 degrees C or 25 degrees C. Growth, feed intake, feed efficiency and protein efficiency ratio, were higher at the higher water temperature. At each water temperatures fish growth and feed efficiency were. higher with the glucose diet. Plasma glucose levels were not influenced by water temperature but were higher in fish fed the glucose diet. Hepatosomatic index and liver glycogen were higher at the lower water temperature and within each water temperature in fish fed the glucose diet. No effect of water temperature on enzymes activities was observed, except for hexokinase and GK which were higher at 25 degrees C. Hepatic hexokinase and pyruvate kinase activities were not influenced by diet composition, whereas glucose-6-phosphate dehydrogenase activity was higher in fish fed the glucose diet. Higher GK activity was observed in fish fed the glucose diet. GK gene expression was higher at 25 degrees C in fish fed the waxy maize starch diet while in fish fed the glucose diet, no temperature effect on GK gene expression was observed. Hepatic G6Pase activities and gene expression were neither influenced by dietary carbohydrates nor water temperature. Overall, our data suggest that in gilthead sea bream juveniles hepatocytes dietary carbohydrate source and temperature affect more intensively GK, the enzyme responsible for the first step of glucose uptake, than G6Pase the enzyme involved in the last step of glucose hepatic release.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7