Effects of dietary phospholipid on lipase activity, antioxidant capacity and lipid metabolism-related gene expression in large yellow croaker larvae (Larimichthys crocea).

Abstract

It was previously shown that lipid content of the whole larvae body fed the phospholipid (PL)-devoid diet was significantly lower than that of larvae fed PL-supplemented diets (P<0.05) (Feng et al., unpublished results). The mechanisms involved remain unclear and were explored from the perspective of fatty acids delivery, uptake, synthesis and oxidation in the present study. Besides, this study was also designed to investigate the effect of dietary PL on antioxidant capacity in large yellow croaker larvae (Larimichthys crocea). Triplicate groups of larvae (initial body weight: 3.86±0.24mg) were fed three isonitrogenous and isolipidic diets with increasing levels of PL (2.53%, 6.32% and 12.7%) eight times daily for 30days. Results showed that the specific activities of superoxide dismutase and catalase were significantly higher in 12.7% PL group compared to those in 2.53% PL group (P<0.05), while an opposite trend was observed for MDA content (P<0.05). The specific activity of lipase and the mRNA abundance of fatty acids delivery and uptake-related genes, including lipoprotein lipase, hepatic lipase and fatty acids translocase (cluster of differentiation) were significantly higher in 12.7% PL group than those in 2.52% group (P<0.05). Compared to 2.53% PL group, the transcript levels of fatty acid synthase and stearoyl-CoA desaturase I were significantly lower in 6.32% PL group (P<0.05), while peroxisome proliferators-activated receptor α, carnitine palmitoyl transferase-I and acyl CoA oxidase mRNA expression levels were significantly higher in 12.7% PL group (P<0.05). These results indicated that dietary PL could enhance antioxidant capacity of larvae. Dietary PL might regulate lipid metabolism in large yellow croaker larvae by modulating fatty acids delivery, uptake, synthesis and oxidation at transcriptional level and improved fatty acids delivery and uptake might be responsible for higher body lipid content in 6.32% and 12.7% groups.