Panserat S, Capilla E, Gutierrez J, Frappart P O, Vachot C, Plagnes-Juan E, Aguirre P, Brèque J, Kaushik S
Laboratory of Fish Nutrition, INRA-IFREMER, 64310 St-Pée-sur-Nivelle, France.
Comp Biochem Physiol B Biochem Mol Biol. 2001 Feb;128(2):275-83. doi: 10.1016/s1096-4959(00)00322-5.
The low dietary starch utilisation by rainbow trout (Oncorhynchus mykiss) may be attributed to a dysfunction of the nutritional regulation of the hepatic glucose/glucose-6-phosphate cycle. The present study was initiated to analyse the regulation of activity and gene expression of hepatic glucokinase (GK) and glucose-6-phosphatase (G6Pase) by dietary carbohydrates in this species. We found that even a single meal containing 24% of glucose is sufficient to induce the GK expression (mRNA and activity) as in mammals. In contrast, although the inhibitory effect of dietary glucose on G6Pase expression is observed at the molecular level, the G6Pase activity is not significantly inhibited by dietary glucose. Thus, in contrast to the gluconeogenic G6Pase enzyme, a rapid adaptation of the hepatic glycolytic GK enzyme to dietary glucose seems effective in rainbow trout. These results suggest that in carnivorous rainbow trout, the liver is capable to strongly regulate the utilisation of glucose but not the synthesis of glucose.
虹鳟（Oncorhynchus mykiss）对膳食淀粉利用率较低，这可能归因于肝脏葡萄糖/葡萄糖-6-磷酸循环营养调节功能障碍。本研究旨在分析该物种中膳食碳水化合物对肝脏葡萄糖激酶（GK）和葡萄糖-6-磷酸酶（G6Pase）活性及基因表达的调节作用。我们发现，即使是一顿含有24%葡萄糖的餐食，也足以像在哺乳动物中那样诱导GK表达（mRNA和活性）。相反，虽然在分子水平上观察到膳食葡萄糖对G6Pase表达有抑制作用，但膳食葡萄糖对G6Pase活性并无显著抑制。因此，与糖异生的G6Pase酶不同，肝脏糖酵解的GK酶对膳食葡萄糖的快速适应性在虹鳟中似乎是有效的。这些结果表明，在肉食性虹鳟中，肝脏能够强烈调节葡萄糖的利用，但不能调节葡萄糖的合成。
