The liver is the main site of de novo lipogenesis in poultry, and hepatic lipid metabolism disorder will lead to excessive abdominal fat deposition or fatty liver disease, finally causing huge economic loss. The present study was conducted to investigate developmental changes in hepatic lipid metabolism of chicks from embryonic periods to the first week after hatching. Liver samples were collected from embryonic day 11 (E11) to the age of day 7 posthatch (D7) for lipid metabolism analysis. Hematoxylin-eosin and Oil Red O staining analysis showed that hepatic lipids increased gradually during embryonic period and declined posthatch; The sum of hepatic triglycerides and cholesterol reached the peak at E19 and D1 by ELISA analysis (P < 0.05). Acetyl-CoA carboxylase, fatty acid synthase, and acyl-CoA desaturase 1 mRNA expression in the liver were higher from E17 to D1 with the peak at E19 when compared with those at E13 and E15 (P < 0.05). Hepatic elongase of very long-chain fatty acids 6 and microsomal triglyceride transfer protein mRNA abundance were lower during embryonic periods but reached relative higher level after hatching (P < 0.05). On the contrary, hepatic carbohydrate response element binding protein (ChREBP), carnitine palmitoyltransferase 1, and peroxisome proliferators-activated receptor α expression were higher during embryonic periods but decreased posthatch (P < 0.05). The mRNA abundance of sterol-regulatory element binding protein 1c was the lowest at E13 and E15, then increased gradually from E17 to D1, while decreased from D3 to D7 little by little (P < 0.05). In summary, hepatic lipogenesis genes have different expression patterns during the embryonic periods and the first week of posthatch, which might be activated by ChREBP during embryonic periods; fatty acid oxidation was enhanced around the hatched day but declined posthatch. These findings will broaden the understanding of physiological characteristics and dynamic pattern about hepatic lipid metabolism in chicks.

中文翻译：

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雏鸡在胚胎期和孵化后第一周肝脏脂质代谢的发育变化。

肝脏是家禽从头脂肪形成的主要部位，肝脏脂质代谢紊乱将导致腹部脂肪过多沉积或脂肪肝疾病，最终造成巨大的经济损失。本研究旨在调查雏鸡从胚胎期到孵化后第一周肝脏脂质代谢的发育变化。从胚胎第11天（E11）到孵化后第7天（D7）收集肝脏样品，以进行脂质代谢分析。苏木精-伊红和油红O染色分析表明，肝脂质在胚胎期逐渐增加，孵化后下降。ELISA法测得肝甘油三酯和胆固醇的总和在E19和D1达到峰值（P <0.05）。乙酰辅酶A羧化酶，脂肪酸合酶，从E17到D1，肝脏中的酰基辅酶A和酰基辅酶A去饱和酶1 mRNA表达高于E13和E15（P <0.05）。极长链脂肪酸6的肝延长酶和微粒体甘油三酸酯转移蛋白mRNA的丰度在胚胎期较低，但在孵化后达到相对较高的水平（P <0.05）。相反，肝糖反应元件结合蛋白（ChREBP），肉碱棕榈酰转移酶1和过氧化物酶体增殖物激活的受体α表达在胚胎期较高，但孵化后降低（P <0.05）。固醇调节元件结合蛋白1c的mRNA丰度在E13和E15最低，然后从E17逐渐增加至D1，而从D3逐渐降低至D7（P <0.05）。综上所述，肝脂肪生成基因在胚胎期和孵化后第一周的表达方式不同，可能在胚胎期被ChREBP激活。孵化当天，脂肪酸氧化增强，但孵化后下降。这些发现将拓宽对雏鸡肝脏脂质代谢的生理特性和动态模式的了解。