Hu Wei, Mai Kang-Sen, Luo Zhi, Zheng Jia-Lang, Huang Chao, Pan Ya-Xiong
Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, People's Republic of China.
Fish Physiol Biochem. 2016 Aug;42(4):1093-105. doi: 10.1007/s10695-016-0200-z. Epub 2016 Jan 28.
The aim of the present study was to explore the effect of waterborne zinc (control, 0.85, 2.20, 3.10 mg/l, respectively) exposure on lipid deposition and metabolism in the hepatopancreas and muscle of grass carp Ctenopharyngodon idella. The lipid content, Zn accumulation, and the activities and expression levels of several enzymes involved in lipid metabolism were determined in hepatopancreas and muscle. Waterborne Zn exposure reduced growth performance and increased Zn accumulation in both tested tissues. In hepatopancreas, Zn exposure increased lipid content, the activities of lipogenic enzymes, such as 6PGD, G6PD, ME, ICDH and FAS, as well as the mRNA expression level of G6PD, 6PGD, ICDH, FAS and SREBP-1. But the activity of CPT I and the mRNA expression of HSL, CPT Iα1a, CPT Iα2a and PPARα were down-regulated by Zn exposure. In contrast, in muscle, waterborne Zn exposure decreased lipid deposition, activities of 6GPD, ICDH and ME, as well as the mRNA expression level of G6PD, ICDH, ME, FAS and SREBP-1. However, the activity of CPT I as well as the mRNA expression level of PPARα, HSL, CPT Iα2a, CPT Iα1b and CPT Iβ were up-regulated by Zn exposure. Our results indicate that waterborne Zn increases lipid content by up-regulating lipogenesis and down-regulating lipolysis in hepatopancreas. But, in muscle, waterborne Zn reduces lipid accumulation by up-regulating lipolysis and down-regulating lipogenesis. Differential patterns of lipid deposition, enzymatic activities and genes' expression indicate the tissue-specific regulatory mechanism in fish.
本研究的目的是探讨水体锌暴露（对照组、0.85、2.20、3.10毫克/升）对草鱼（Ctenopharyngodon idella）肝胰腺和肌肉中脂质沉积及代谢的影响。测定了肝胰腺和肌肉中的脂质含量、锌积累量以及几种参与脂质代谢的酶的活性和表达水平。水体锌暴露降低了生长性能，并增加了两个受试组织中的锌积累量。在肝胰腺中，锌暴露增加了脂质含量、脂肪生成酶（如6磷酸葡萄糖脱氢酶、葡萄糖6磷酸脱氢酶、苹果酸酶、异柠檬酸脱氢酶和脂肪酸合酶）的活性，以及葡萄糖6磷酸脱氢酶、6磷酸葡萄糖脱氢酶、异柠檬酸脱氢酶、脂肪酸合酶和固醇调节元件结合蛋白-1的mRNA表达水平。但锌暴露下调了肉碱棕榈酰转移酶I的活性以及激素敏感脂肪酶、肉碱棕榈酰转移酶Iα1a、肉碱棕榈酰转移酶Iα2a和过氧化物酶体增殖物激活受体α的mRNA表达。相反，在肌肉中，水体锌暴露降低了脂质沉积、6磷酸葡萄糖脱氢酶、异柠檬酸脱氢酶和苹果酸酶的活性，以及葡萄糖6磷酸脱氢酶、异柠檬酸脱氢酶、苹果酸酶、脂肪酸合酶和固醇调节元件结合蛋白-1的mRNA表达水平。然而，锌暴露上调了肉碱棕榈酰转移酶I的活性以及过氧化物酶体增殖物激活受体α、激素敏感脂肪酶、肉碱棕榈酰转移酶Iα2a、肉碱棕榈酰转移酶Iα1b和肉碱棕榈酰转移酶Iβ的mRNA表达水平。我们的结果表明，水体锌通过上调肝胰腺中的脂肪生成和下调脂肪分解来增加脂质含量。但是，在肌肉中，水体锌通过上调脂肪分解和下调脂肪生成来减少脂质积累。脂质沉积、酶活性和基因表达的差异模式表明了鱼类中的组织特异性调节机制。
