FASTING-INDUCED MODIFICATIONS OF FATTY-ACIDS COMPOSITION IN BROWN ADIPOSE-TISSUE

1. Effect of fasting for 72 h on fatty acid (FA) composition was studi ed in triglyceride and phospholipid fractions of rat interscapular bro wn adipose tissue (BAT). 2. Fasting decreased the body and BAT weights , and tissue DNA was significantly decreased by fasting. The tissue tr iglyceride and phospholipid levels were not affected by fasting. 3. In triglyceride FA of BAT the extent of unsaturation was increased as as sessed by mol% of polyunsaturated FA, the ratio of polyunsaturated FA to saturated FA and the unsaturation index in the fasted state. 4. In phospholipid FA of BAT the extent of unsaturation also increased as as sessed by the same indices for TG. 5. These results, especially in pho spholipid FA of BAT, were in good agreement with the previous report i n the cold-acclimated rats, suggesting that BAT function is, at least in part, stimulated during fasting.