The pattern of fatty acid synthesis in lactating rabbit mammary gland studied in vivo

Abstract

The biosynthesis of fatty acids has been studied in lactating rabbits at 6h after intravenous injection of sodium [1-14C]acetate. The specific radioactivities of the individual fatty acids (C6:0 to C14:0) and the proportions of these fatty acids synthesized were similar in mammary tissue and milk. Hexanoic acid had the highest specific radioactivity, and the C8:0–C14:0 fatty acids had similar specific radioactivities, which were about five times those of C16 and C18 acids. No radioactivity was detected in fatty acids of chain length <C14 in the liver, blood or adipose tissue and the specific radioactivities of fatty acids of chain length >C14 in these tissues were similar to those of the long-chain fatty acids in the milk and mammary gland. The results show that the C4:0–C14:0 fatty acids are synthesized within the mammary gland rather than by fatty acid uptake from circulating blood or by oxidation of long-chain fatty acids within the gland. We conclude that de novo synthesis of esterified fatty acids in vivo by this tissue has a high degree of chain-length specificity.