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Angiopoietin-like 4 (ANGPTL4) is a potent regulator of TAG metabolism, but knowledge of the mechanisms underlying ANGPTL4 transcription in response to fatty acids is still limited in teleost. In the current study, we explored the molecular characterisation of ANGPTL4 and regulatory mechanisms of ANGPTL4 in response to fatty acids in large yellow croaker (Larimichthys crocea). Here, croaker angptl4 contained a 1416 bp open reading frame encoding a protein of 471 amino acids with highly conserved 12-amino acid consensus motif. Angptl4 was widely expressed in croaker, with the highest expression in the liver. In vitro , oleic and palmitic acids (OA and PA) treatments strongly increased angptl4 mRNA expression in croaker hepatocytes. Moreover, angptl4 expression was positively regulated by PPAR family (PPAR- α , β and γ), and expression of PPAR γ was also significantly increased in response to OA and PA. Moreover, inhibition of PPAR γ abrogated OA- or PA-induced angptl4 mRNA expression. Beyond that, PA might increase angptl4 expression partly via the insulin signalling. Overall, the expression of ANGPTL4 is strongly upregulated by OA and PA via PPAR γ in the liver of croaker, which contributes to improve the understanding of the regulatory mechanisms of ANGPTL4 in fish. [ABSTRACT FROM AUTHOR]

A 10-week feeding trial was conducted to investigate the effect of dietary curcumin (CC) on growth antioxidant responses, fatty acid composition, and expression of lipid metabolism-related genes of large yellow croaker fed a high-fat diet (HFD). Four diets (lipid level at 18 %) were formulated with different levels of curcumin (0, 0·02, 0·04 and 0·06 %). The best growth performance was found in the 0·04 % curcumin group, with the body and hepatic lipid levels lower than the control group (0 % CC). The content of TAG, total cholesterol and LDL-cholesterol was the least in the 0·06 % curcumin group. The lowest malondialdehyde and the highest superoxide dismutase, catalase and total antioxidant capacity were observed in the 0·04 % curcumin group. The 0·04 % curcumin group had higher expression of Δ6fad, elovl5 and elovl4 and showed higher hepatic n-6 and n-3 PUFA. Expression of ppara, cpt1, and aco was significantly increased, while expression of srebp1 and fas was dramatically decreased in curcumin groups compared with the control group. Overall, 0·04 % curcumin supplementation could mitigate the negative effects caused by HFD and promote growth via reducing hepatic lipid deposition, improving antioxidant activity and increasing PUFA of large yellow croaker. To conclude, abnormal hepatic lipid deposition was probably due to increased fatty acid oxidation and reduced de novo synthesis of fatty acids. [ABSTRACT FROM AUTHOR]

Abstract: The study was conducted to investigate the effects of dietary tea polyphenols (TP) on growth performance, biochemical and antioxidants responses, fatty acid composition, and lipid metabolism‐related gene expressions of large yellow croaker (Larimichthys crocea). Four diets were formulated with different levels of TP (0.00%, 0.01%, 0.02% and 0.05%). Results showed that growth performance of L. crocea were not different among dietary treatments. Compared with the control group, fish in 0.02% TP group had lower body and hepatic lipid content and lower total cholesterol content. The minimum content of triglycerides and low‐density lipoprotein‐cholesterol were found in 0.05% TP group. Hepatic n‐6 PUFA and n‐3 PUFA were significantly higher in TP supplementation groups. Malondialdehyde content was lower in TP supplementation groups, and superoxide dismutase activity was higher in 0.01% TP group than the control group. The mRNA expressions of carnitine palmitoyltransferase1, acyl‐CoA oxidase and peroxisome proliferators‐activated receptor α were up‐regulated in 0.01% and 0.02% TP groups, while lipoprotein lipase expression was down‐regulated in TP supplementation groups than the control group. Results suggested that 0.01%–0.02% TP supplementation could reduce the deposition of liver lipid of L. crocea caused by high‐lipid diet, which might be due to the increase in lipid oxidation related gene expressions. [ABSTRACT FROM AUTHOR]