Effect of cold acclimation on brown adipose tissue fatty acid synthesis in rats adapted to a high-protein, carbohydrate-free diet

Metabolism. 2001 Dec;50(12):1493-8. doi: 10.1053/meta.2001.27197.

Abstract

The effect of cold acclimation on brown adipose tissue (BAT) fatty acid synthesis was investigated in rats adapted to a high-protein, carbohydrate-free diet. At an ambient temperature (25 degrees C), rates of fatty acid synthesis in BAT from rats adapted to the high-protein diet were reduced to 27% of rats fed the balanced diet and increased markedly after cold acclimation (10 days at 4 degrees C), although the increase was smaller than in control rats. BAT weight increase induced by cold acclimation was smaller in rats fed the high-protein diet (30%) than in controls (100%). When expressed per whole tissue, maximal activities of BAT glucose-6-phosphate dehydrogenase, malic enzyme, adenosine triphosphate (ATP)-citrate lyase, and acetyl-coenzyme A carboxylase were markedly reduced in high-protein diet-adapted rats at 25 degrees C and increased after cold acclimation in BAT from the 2 groups. However, when expressed per milligram protein, only acetyl-coenzyme A carboxylase showed an increase in both controls and in rats fed the high-protein diet. G6P-dehydrogenase, malic enzyme, and ATP-citrate lyase increased (per milligram protein) only in rats adapted to the high-protein diet and actually decreased in BAT from cold-acclimated control rats. Initial (before activation) pyruvate dehydrogenase (PDH) complex activity was lower in BAT from rats fed the high-protein diet at 25 degrees C and increased in cold-acclimated rats from the 2 groups. Circulating levels of insulin decreased in the 2 groups after cold acclimation. The data suggest that the cold acclimation-induced increase in BAT lipogenesis in rats adapted to the high-protein diet was due to a restoration of sympathetic activity, which induced both BAT hyperplasia and activation of adipocyte free fatty acid (FFA) synthesis, with an important participation of acetyl-coenzyme A carboxylase and pyruvate dehydrogenase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Citrate (pro-S)-Lyase / metabolism
  • Acclimatization*
  • Acetyl-CoA Carboxylase / metabolism
  • Adaptation, Physiological
  • Adipose Tissue, Brown / anatomy & histology
  • Adipose Tissue, Brown / metabolism*
  • Animals
  • Body Temperature
  • Cold Temperature*
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Proteins / administration & dosage*
  • Fatty Acids / biosynthesis*
  • Glucosephosphate Dehydrogenase / metabolism
  • Malate Dehydrogenase / metabolism
  • Male
  • Organ Size
  • Pyruvate Dehydrogenase Complex / metabolism
  • Rats
  • Rats, Wistar

Substances

  • Dietary Carbohydrates
  • Dietary Proteins
  • Fatty Acids
  • Pyruvate Dehydrogenase Complex
  • Malate Dehydrogenase
  • Glucosephosphate Dehydrogenase
  • ATP Citrate (pro-S)-Lyase
  • Acetyl-CoA Carboxylase