Interactive effects of dietary cholesterol and phospholipids on growth and metabolism of juvenile swimming crab, Portunus trituberculatus

Abstract

Cholesterol and phospholipid play an important role in growth, molt and reproduction for crustaceans, although dietary optimum requirement of cholesterol and phospholipids has been determined for Portunus trituberculatus, but it is still unclear whether there was an interaction on each other. Therefore, an eight-week feeding trial was conducted to evaluate the interactive effects of dietary cholesterol and phospholipid levels on growth performance, fatty acid composition in hepatopancreas and the expression of genes related to cholesterol and phospholipid metabolism of Portunus trituberculatus. Six isonitrogenous and isolipid diets were formulated to contain two cholesterol levels (0 % and 0.5 %) and three phospholipid levels (0 %, 2 % and 4 %). The results indicated that specific growth rate (SGR) significantly increased with the increase of dietary phospholipid levels, however, there were no interactive effects between dietary cholesterol and phospholipid on percent weight gain (PWG) and SGR (P > 0.05). The concentration of total-cholesterol (T-CHO) and triacylglycerol (TAG) in hemolymph significantly affected by the interaction between cholesterol and phospholipid (P < 0.05), crabs fed diets with 0.5 % cholesterol supplementation had higher low-density lipoprotein cholesterol (LDL-C) concentration in hemolymph than those fed diets without cholesterol supplementation regardless of phospholipid supplementation (P < 0.05). TAG and LDL-C concentration in hepatopancreas were significantly affected by the interaction between cholesterol and phospholipid (P < 0.05), crabs fed diets with 0.5 % cholesterol supplementation had significantly higher T-CHO and LDL-C concentration in hepatopancreas than those fed diets without cholesterol supplementation (P < 0.05). There was a significant interaction between dietary cholesterol and phospholipid on activity of catalase (CAT) and the concentration of glutathione (GSH) and malondialdehyde (MDA) in hepatopancreas (P < 0.05), and crabs fed diets with cholesterol supplementation had higher superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) in hepatopancreas than those fed diets without cholesterol supplementation (P < 0.05). Moreover, EPA, LC-PUFA, n-3 PUFA, n-3/n-6 PUFA and DHA/EPA in hepatopancreas were significantly affected by the interaction between dietary cholesterol and phospholipid (P < 0.05). The expression of adenosine triphosphate binding cassette transporter G1 (abcg1), C-type 1 class Niemann-Pick protein (npc1), scavenger receptor B (srb) and low-density lipoprotein receptor (ldlr) were up-regulated by dietary cholesterol and phospholipid levels (P < 0.05). In conclusion, the results indicated that dietary appropriate cholesterol and phospholipid levels could significantly improve growth performance and promote cholesterol metabolism.