Lipids

, Volume 46, Issue 2, pp 189–199

Insulin Stimulates Lipogenesis and Attenuates Beta-Oxidation in White Adipose Tissue of Fed Rainbow Trout

  • S. Polakof
  • F. Médale
  • L. Larroquet
  • C. Vachot
  • G. Corraze
  • S. Panserat
Original Article

Abstract

As lipid deposition tissue in fish, the white adipose tissue (WAT) has important functions related to reproduction and the challenges of long-term fasting. In the study reported here, we infused fish fed a high-carbohydrate diet with two doses of insulin for 5 days in order to explore the effects of this hormone on lipogenesis and beta-oxidation-related enzymes. We demonstrated the presence of some of the main lipogenic enzymes at molecular, protein and activity levels (ATP-citrate lyase and fatty acid synthase). However, while ATP-citrate lyase was unexpectedly down-regulated, fatty acid synthase was up-regulated (at protein and activity levels) in an insulin dose-dependent manner. The main enzymes acting as NADPH donors for lipogenesis were also characterized at biochemical and molecular levels, although there was no evidence of their regulation by insulin. On the other hand, lipid oxidation potential was found in this tissue through the measurement of gene expression of enzymes involved in β-oxidation, highlighting two carnitine palmitoyltransferase isoforms, both down-regulated by insulin infusion. We found that insulin acts as an important regulator of trout WAT lipid metabolism, inducing the final stage of lipogenesis at molecular, protein and enzyme activity levels and suppressing β-oxidation at least at a molecular level. These results suggest that WAT in fish may have a role that is important not only as a lipid deposition tissue but also as a lipogenic organ (with possible involvement in glucose homeostasis) that could also be able to utilize the lipids stored as a local energy source.

Keywords

Insulin Fish Dietary carbohydrates White adipose tissue Lipogenesis Lipid oxidation 

Abbreviations

6PGDH

6-Phosphogluconate dehydrogenase

ACLY

ATP citrate lyase

CPT

Carnitine palmitoyltransferase

EF1α

Elongation factor 1 alpha

FFA

Free fatty acids

G6PDH

Glucose 6-phosphate dehydrogenase

HOAD

3-Hydroxyacyl-CoA dehydrogenase

HSL

Hormone-sensitive lipase

ICDH

Isocitrate dehydrogenase

LPL

Lipoprotein lipase

ME

Malic enzyme

NAPDH

Nicotine adenine dinucleotide phosphate, reduced

TAG

Triacylglycerols

TNF

Tumor necrosis factor-alpha

WAT

White adipose tissue

Copyright information

© AOCS 2011

Authors and Affiliations

  • S. Polakof
    • 1
    • 2
  • F. Médale
    • 1
  • L. Larroquet
    • 1
  • C. Vachot
    • 1
  • G. Corraze
    • 1
  • S. Panserat
    • 1
  1. 1.INRA, UMR1067 Nutrition Aquaculture et Génomique, Pôle d’hydrobiologie, CD918Saint-Pée-sur-NivelleFrance
  2. 2.Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da SaúdeFacultade de Bioloxía, Universidade de VigoVigoSpain

Personalised recommendations