Huang Hongli, Zhang Yu, Cao Mingyue, Xue Liangyi, Shen Weiliang
College of Marine Sciences, Ningbo University, 818 Fenghua Road, Ningbo, 315211, Zhejiang, People's Republic of China.
Collaborative Innovation Center for Zhejiang Marine High-Efficiency and Healthy Aquaculture, Ningbo University, Ningbo, Zhejiang, 315211, China.
Fish Physiol Biochem. 2018 Feb;44(1):387-400. doi: 10.1007/s10695-017-0442-4. Epub 2017 Nov 16.
To investigate the effects of fasting on lipid metabolism in spotted seabass muscle and liver tissues, we analyzed mRNA levels and enzyme activities of lipoprotein lipase (LPL), hormone-sensitive lipase (HSL) and fatty acid synthetase (FAS), and the relationship among fat content, mRNA level, and enzyme activity during fasting of 35 days. The results showed that expressions of all the three genes were ubiquitous. During the fasting experiment, the hepatosomatic index (HSI) and fat content of muscle and liver tissues significantly decreased before 5 days of fasting (P < 0.05). mRNA levels of LPL increased significantly after 5 days of fasting in liver and 7 days in muscle. Abundance of HSL transcripts increased significantly after 14 days of fasting in both muscle and liver. The activities of LPL and HSL presented a trend that increased firstly, decreased subsequently, and then raised again with the prolonged fasting experiment (P < 0.05). However, activities and mRNA levels of FAS decreased significantly after 1 day of fasting in both muscle and liver. Moreover, activities and mRNA levels of FAS showed a moderate correlation in muscle. These results suggested that FAS had a sooner response to fasting than LPL and HSL in both muscle and liver tissues. LPL and HSL played important roles in lipolysis mainly by increasing enzyme activities in the early stage of fasting and mRNA levels in the later stage of fasting in both muscle and liver. Our results also provided useful information on regulating muscle fat content by fasting.
为研究禁食对花鲈肌肉和肝脏组织脂质代谢的影响，我们分析了脂蛋白脂肪酶（LPL）、激素敏感性脂肪酶（HSL）和脂肪酸合成酶（FAS）的mRNA水平及酶活性，以及禁食35天期间脂肪含量、mRNA水平和酶活性之间的关系。结果表明，这三个基因的表达均普遍存在。在禁食实验期间，禁食前5天，肝体指数（HSI）以及肌肉和肝脏组织的脂肪含量显著下降（P < 0.05）。禁食5天后肝脏中LPL的mRNA水平显著升高，禁食7天后肌肉中LPL的mRNA水平显著升高。禁食14天后，肌肉和肝脏中HSL转录本的丰度均显著增加。随着禁食时间延长，LPL和HSL的活性呈现先升高、后降低、再升高的趋势（P < 0.05）。然而，禁食1天后，肌肉和肝脏中FAS的活性和mRNA水平均显著下降。此外，肌肉中FAS的活性和mRNA水平呈中度相关。这些结果表明，在肌肉和肝脏组织中，FAS对禁食的反应比LPL和HSL更快。LPL和HSL在脂肪分解中发挥重要作用，主要是通过在禁食早期增加酶活性以及在禁食后期增加mRNA水平来实现的。我们的研究结果还为通过禁食调节肌肉脂肪含量提供了有用信息。
