Effect of dietary docosahexaenoic acid on lipogenesis and lipolysis in black sea bream, Acanthopagrus schlegeli

摘要

Hatchery-reared juvenile black sea breams are characterized by a low level of highly unsaturated fatty acids in their bodies, as compared with wild fish. To assess the effect of docosahaxaenoic acid (DHA) on lipogenic and lipolysis enzymes, one-year fish were reared on a casein-based purified diet and a DHA fortified diet (1.5% DHA ethyl ester/kg diet) for 60 d, followed with a period of 55 d for starvation. Dietary DHA was effectively incorporated into the fish body. Fortification of DHA depressed activities of glucose-6-phosphate dehydrogenase and NADP-isocitrate dehydrogenase as lipogenic enzymes in the hepatopancreas and intraperitoneal fat body. Carnitine palmitoyltransferase as lipolysis enzyme in the hepatopancreas was active in the DHA fortified fish. Starvation after feeding experiment induced increased carnitine palmitoyltransferase activity in both control and DHA fortified fish and the activity remained higher in the DHA fortified fish, while the monoenes were selectively consumed prior to highly unsaturated fatty acids. These results indicated that dietary DHA depressed lipogenesis and activated lipolysis.