Influence of Diet on in Vitro and in Vivo Rates of Fatty Acid Synthesis in Coho Salmon [Oncorhynchus Kisutch (Walbaum)

Abstract

The site and the influence of diet on fatty acid synthesis in juvenile coho salmon were investigated. Tritiated water was used to obtain estimates of the rates of fatty acid synthesis. Liver slices and mesenteric glucose and tritiated water. The rate of fatty acid synthesis averaged 1172 +/- 126 and 40 +/- 8 nmoles tritium incorporated into fatty acids per 2 hours per 100 mg of liver and adipose tissue, respectively. The pattern of [1-14C]acetate incorporation into fatty acids in the liver slices indicated that de novo fatty acid synthesis, rather than chain elongation, was occurring. In vivo rates of fatty acid synthesis in liver were approximately linear for 30 minutes. In vivo rates of fatty acid synthesis averaged 244 +/- 14 and 44 +/- 11 dpm of tritium incorporated into fatty acids per 20 minutes per 100 mg of liver and adipose tissue, respectively. Consumption of a high-fat diet or fasting for 2 days decreased the in vitro and in vivo rates of fatty acid synthesis in fish liver. Refeeding fasted (48 hours) fish with a high-carbohydrate diet for 4 hours increased the rate of hepatic fatty acid synthesis. The major site of fatty acid synthesis in coho salmon appears to be the liver, and dietary alterations influence the rate of fatty acid synthesis in the liver.