Glucose and lipid metabolism in the pancreas of rainbow trout is regulated at the molecular level by nutritional status and carbohydrate intake
- 602 Downloads
Glucose and lipid metabolism in pancreatic islet organs is poorly characterized. In the present study, using as a model the carnivorous rainbow trout, a glucose-intolerant fish, we assessed mRNA expression levels of several genes involved in glucose and lipid metabolism (including ATP-citrate lyase; carnitine palmitoyltransferase-1 isoforms, CPT; the mitochondrial isoform of the phosphoenolpyrutave carboxykinase, mPEPCK and pyruvate kinase, PK) and glucosensing (glucose transporter type 2, Glut2; glucokinase, GK and the potassium channel, KATP) in Brockmann bodies. We evaluated the response of these parameters to changes in feeding status (food deprived vs. fed fish) as well as to changes in the amount of carbohydrate (dextrin) in the diet. A general inhibition of the glycolytic (including the glucosensing marker GK) and β-oxidation pathways was found when comparing fed versus food-deprived fish. When comparing fish feeding on either low- or high-carbohydrate diets, we found that some genes related to lipid metabolism were more controlled by the feeding status than by the carbohydrate content (fatty acid synthase, CPTs). Findings are discussed in the context of pancreatic regulation of glucose and lipid metabolism in fish, and show that while trout pancreatic metabolism can partially adapt to a high-carbohydrate diet, some of the molecular actors studied seem to be poorly regulated (KATP) and may contribute to the glucose intolerance observed in this species when fed high-carbohydrate diets.
KeywordsGlucose and lipid metabolism Dietary carbohydrates Brockmann bodies Fish
S. Polakof was recipient of a postdoctoral fellowship from the Xunta de Galicia (Program Ángeles Alvariño). We acknowledge the technical staff (Y. Hontang, F. Sandres, and F. Terrier) of the INRA experimental fish farm of Donzacq for supplying the experimental animals. This study was supported by research grants from Agence Nationale de la Recherche (ANR-08-JCJC-0025-01).
- Joy P (2002) Cloning, sequencing and expression of the tilapia glucokinase. M.Sc. Thesis, Department of Biology, Dalhousie UniversityGoogle Scholar
- Liang Y, Jetton TL, Zimmerman EC, Najafi H, Berner DK, Matschinsky FM, Magnuson MA (1994) Effects of glucose on insulin secretion, glucokinase activity, and transgene expression in transgenic mouse islets containing an upstream glucokinase promoter-human growth hormone fusion gene. Diabetes 43:1138–1145PubMedCrossRefGoogle Scholar
- Macleod JJR (1922) The source of insulin. A study of the effect produced on blood sugar by extracts of the pancreas and principal islets of fishes. J Metab Res 2:149–172Google Scholar
- Mommsen TP, Plisetskaya EM (1991) Insulin in fishes and agnathans: history, structure, and metabolic regulation. Rev Aquat Sci 4:225–259Google Scholar
- Moore CA, Kittilson JD, Ehrman MM, Sheridan MA (1999) Rainbow trout (Oncorhynchus mykiss) possess two somatostatin mRNAs that are differentially expressed. Am J Physiol Regul Integr Comp Physiol 277:1553–1561Google Scholar
- Newsholme P, Gaudel C, McClenaghan N (2010) Nutrient regulation of insulin secretion and β-cell functional integrity. In: Islam MS (ed) The islets of Langerhans. Springer, DordrechtGoogle Scholar
- Plisetskaya EM, Duguay S, Schrgibman MP, Scanes CE, Pang P (1993) Pancreatic hormones and metabolism in ectotherm vertebrates: current views. In: Schreibman MP, Scanes CG, Pang PKT Jr (eds) The endocrinology of growth. Development and metabolism in vertebrates. Academic Press, New York, pp 266–287Google Scholar
- Polakof S, Mommsen TP, Soengas JL (2011) Glucosensing and glucose homeostasis: from fish to mammals. Comp Biochem Physiol A Mol Integr Physiol 160:123–149Google Scholar
- Seiliez I, Panserat S, Lansard M, Polakof S, Plagnes-Juan E, Surget A, Dias K, Larquier M, Kaushik S, Skiba-Cassy S (2011) Dietary carbohydrate to protein ratio affects TOR signaling and metabolism-related gene expression in the liver and muscle of rainbow trout after a single meal. Am J Physiol Regul Integr Comp Physiol 300:R733–R743PubMedCrossRefGoogle Scholar