Chen Guang-Hui, Luo Zhi, Chen Feng, Shi Xi, Song Yu-Feng, You Wen-Jing, Liu Xu
Hubei Provincial Engineering Laboratory for Pond Aquaculture, Fishery College, Huazhong Agricultural University, Wuhan 430070, China.
Hubei Provincial Engineering Laboratory for Pond Aquaculture, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province, Changde 415000, China.
Comp Biochem Physiol C Toxicol Pharmacol. 2017 Jul;197:8-18. doi: 10.1016/j.cbpc.2017.04.003. Epub 2017 Apr 11.
The 42-day experiment was conducted to investigate the effects and mechanism of waterborne Fe exposure influencing hepatic lipid deposition in Synechogobius hasta. For that purpose, S. hasta were exposed to four Fe concentrations (0 (control), 0.36, 0.72 and 1.07μM Fe) for 42days. On days 21 and 42, morphological parameters, hepatic lipid deposition and Fe contents, and activities and mRNA levels of enzymes and genes related to lipid metabolism, including lipogenic enzymes (6PGD, G6PD, ME, ICDH, FAS and ACC) and lipolytic enzymes (CPTI, HSL), were analyzed. With the increase of Fe concentration, hepatic Fe content tended to increase but HSI and lipid content tended to decrease. On day 21, Fe exposure down-regulated the lipogenic activities of 6PGD, G6PD, ICDH and FAS as well as the mRNA levels of G6PD, ACCa, FAS, SREBP-1 and PPARγ, but up-regulated CPT I, HSLa and PPARα mRNA levels. On day 42, Fe exposure down-regulated the lipogenic activities of 6PGD, G6PD, ICDH and FAS as well as the mRNA levels of 6PGD, ACCa, FAS and SREBP-1, but up-regulated CPT I, HSLa, PPARα and PPARγ mRNA levels. Using primary S. hasta hepatocytes, specific pathway inhibitors (GW6471 for PPARα and fatostatin for SREBP-1) and activator (troglitazone for PPARγ) were used to explore the signaling pathways of Fe reducing lipid deposition. The GW6471 attenuated the Fe-induced down-regulation of mRNA levels of 6PGD, G6PD, ME, FAS and ACCa, and attenuated the Fe-induced up-regulation of mRNA levels of CPT I, HSLa and PPARα. Compared with single Fe-incubated group, the mRNA levels of G6PD, ME, FAS, ACCa, ACCb and PPARγ were up-regulated while the CPT I mRNA levels were down-regulated after troglitazone pre-treatment; fatostatin pre-treatment down-regulated the mRNA levels of 6PGD, ME, FAS, ACCa, ACCb and SREBP-1, and increased the CPT I and HSLa mRNA levels. Based on these results above, our study indicated that Fe exposure reduced hepatic lipid deposition by down-regulating lipogenesis and up-regulating lipolysis, and PPARα, PPARγ and SREBP-1 pathways mediated the Fe-induced reduction of hepatic lipid deposition in S. hasta.
进行了为期42天的实验，以研究水体铁暴露对矛尾虾虎鱼肝脏脂质沉积的影响及其机制。为此，将矛尾虾虎鱼暴露于四种铁浓度（0（对照）、0.36、0.72和1.07μM铁）下42天。在第21天和第42天，分析了形态学参数、肝脏脂质沉积和铁含量，以及与脂质代谢相关的酶和基因的活性及mRNA水平，包括生脂酶（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、脂肪酸合酶和乙酰辅酶A羧化酶）和脂解酶（肉碱棕榈酰转移酶I、激素敏感脂肪酶）。随着铁浓度的增加，肝脏铁含量呈上升趋势，但肝体指数和脂质含量呈下降趋势。在第21天，铁暴露下调了6 - 磷酸葡萄糖脱氢酶、葡萄糖 - 6 - 磷酸脱氢酶、异柠檬酸脱氢酶和脂肪酸合酶的生脂活性以及葡萄糖 - 6 - 磷酸脱氢酶、乙酰辅酶A羧化酶α、脂肪酸合酶、固醇调节元件结合蛋白 - 1和过氧化物酶体增殖物激活受体γ的mRNA水平，但上调了肉碱棕榈酰转移酶I、激素敏感脂肪酶α和过氧化物酶体增殖物激活受体α的mRNA水平。在第42天，铁暴露下调了6 - 磷酸葡萄糖脱氢酶、葡萄糖 - 6 - 磷酸脱氢酶、异柠檬酸脱氢酶和脂肪酸合酶的生脂活性以及6 - 磷酸葡萄糖脱氢酶、乙酰辅酶A羧化酶α、脂肪酸合酶和固醇调节元件结合蛋白 - 1的mRNA水平，但上调了肉碱棕榈酰转移酶I、激素敏感脂肪酶α、过氧化物酶体增殖物激活受体α和过氧化物酶体增殖物激活受体γ的mRNA水平。使用矛尾虾虎鱼原代肝细胞，采用特异性通路抑制剂（GW6471用于过氧化物酶体增殖物激活受体α，法托司他汀用于固醇调节元件结合蛋白 - 1）和激活剂（曲格列酮用于过氧化物酶体增殖物激活受体γ）来探究铁减少脂质沉积的信号通路。GW6471减弱了铁诱导的6 - 磷酸葡萄糖脱氢酶、葡萄糖 - 6 - 磷酸脱氢酶、苹果酸酶、脂肪酸合酶和乙酰辅酶A羧化酶α mRNA水平的下调，以及铁诱导的肉碱棕榈酰转移酶I、激素敏感脂肪酶α和过氧化物酶体增殖物激活受体α mRNA水平的上调。与单铁孵育组相比，曲格列酮预处理后葡萄糖 - 6 - 磷酸脱氢酶、苹果酸酶、脂肪酸合酶、乙酰辅酶A羧化酶α、乙酰辅酶A羧化酶β和过氧化物酶体增殖物激活受体γ的mRNA水平上调，而肉碱棕榈酰转移酶I mRNA水平下调；法托司他汀预处理下调了6 - 磷酸葡萄糖脱氢酶、苹果酸酶、脂肪酸合酶、乙酰辅酶A羧化酶α、乙酰辅酶A羧化酶β和固醇调节元件结合蛋白 - 1的mRNA水平，并提高了肉碱棕榈酰转移酶I和激素敏感脂肪酶α的mRNA水平。基于上述结果，我们的研究表明，铁暴露通过下调脂肪生成和上调脂肪分解来减少肝脏脂质沉积，而过氧化物酶体增殖物激活受体α、过氧化物酶体增殖物激活受体γ和固醇调节元件结合蛋白 - 1通路介导了铁诱导的矛尾虾虎鱼肝脏脂质沉积减少。
