INCORPORATION OF DELTA(6)-DESATURATION AND DELTA(5)-DESATURATION FATTY-ACIDS IN LIVER MICROSOMAL LIPID CLASSES OF OBESE ZUCKER RATS FED N-6OR N-3 FATTY-ACIDS

The aim of this work was to study the effect of dietary n-6 (as borage oil) and of n-3 (as fish oil) fatty acids on the incorporation - in l iver microsomal lipid classes - of fatty acids involved in Delta(6)- a nd Delta(5)-desaturations in obese Zucker rats compared with their lea n littermates and with Wistar control rats. We observed that body and liver weights were decreased when obese Zucker rats were fed the fish oil diet. The major part of the radioactivity was recovered, in the ob ese Zucker rats, into the neutral lipids and especially into the triac ylglycerols, while it was recovered into the phospholipid classes, esp ecially into phosphatidylcholine, in the two other strains. Results sh ow, in all phenotypes, an increased alpha-linolenic acid Delta(6)-desa turation in PL classes when the rats were fed the fish oil diet. Howev er, a decreased linoleic acid Delta(6)- and Delta(5)-desaturation was observed in obese Zucker rats fed the fish oil diet. The fish oil diet favours the n-3 fatty acid biosynthesis and incorporation into liver microsomal lipid classes to the prejudice of the n-6 fatty acid series . The fatty acid incorporation is simultaneously regulated by the gene tical phenotype and dietary fatty acids.