Effect of estradiol on hepatopancreatic lipid metabolism in the swimming crab, Portunus trituberculatus

Estradiol is an important sex steroid hormone that involved in regulation of animal lipid metabolism. However, the effect of estradiol on lipid metabolism in swimming crab (Portion's trituberculatus) is unclear. The present study investigated the effect of four concentrations of exogenous estradiol (0, 0.01, 0.1 and 1 mu g g(-1) crab weight) on the expression levels of lipid metabolism-related genes, lipid composition and histology of hepatopancreas in the P. trituberculatus. The results showed that the mRNA levels of camitine paltnitoyltransferase I and II (CPT-I and CPT-II) increased significantly at the low concentrations (0.01 mu g g(-1) and 0.1 mu g g(-1)), while decreased significantly in the highest concentration (1 mu g g(-1)). The mRNA levels of acyl-CoA oxidase (ACOX), fatty acid transport protein (FATP), fatty acid-binding protein (FABP), diacylglycerol acyltransferase 1 (DGATI) and acetyl-CoA carboxylase (ACC) were significantly down-regulated. The transcripts of fatty acid synthase (FAS) and fatty acy1 desaturase (FAD) decreased significantly only in 1 mu g g(-1) treatment. All estradiol treatments (0.01, 0.1 and 1 mu g g(-1)) had significantly higher percentages of 20:4n6, 20:5n3 and 22:6n3, but lower percentages of total monounsaturated fatty acids and polar lipids than the control treatment (0 mu g g(-1)). Histological observations indicated the size of B cell became larger under estradiol treatment. The results indicated that estradiol promoted lipid catabolism in the hepatopancreas of P. trituberculatus.