High Levels of Erucic Acid Cause Lipid Deposition, Decreased Antioxidant and Immune Abilities via Inhibiting Lipid Catabolism and Increasing Lipogenesis in Black Carp (Mylopharyngodon piceus)

Abstract

This study investigated the effects of dietary erucic acid (EA) on growth, lipid accumulation, antioxidant and immune abilities, and lipid metabolism in black carp fed six diets containing varying levels of EA (0.00%, 0.44%, 0.81%, 1.83%, 2.74%, and 3.49%), for 8 weeks. Results showed that fish fed the 3.49% EA diet exhibited lower weight gain, compared to those fed the 0.81% EA diet. In a dose-dependent manner, the serum triglycerides and total cholesterol were significantly elevated in the EA groups. The 1.83%, 2.74%, and 3.49% levels of EA increased alanine aminotransferase and aspartate aminotransferase activities, as well as decreased acid phosphatase and alkaline phosphatase values compared to the EA-deficient group. The hepatic catalase activity and transcriptional level were notably reduced, accompanied by increased hydrogen peroxide contents in the EA groups. Furthermore, dietary EA primarily increased the C22:1n-9 and C20:1n-9 levels, while decreasing the C18:0 and C18:1n-9 contents. In the EA groups, expressions of genes, including hsl, cpt1a, cpt1b, and ppara were downregulated, whereas the fas and gpat expressions were enhanced. Additionally, dietary EA elevated the mRNA level of il-1β and reduced the expression of il-10. Collectively, high levels of EA (2.74% and 3.49%) induced lipid accumulation, reduced antioxidative and immune abilities in black carp by inhibiting lipid catabolism and increasing lipogenesis. These findings provide valuable insights for optimizing the use of rapeseed oil rich in EA for black carp and other carnivorous fish species.