Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou 310027, China.
Department of Animal Science, College of Life Sciences and Food Engineering, Hebei University of Engineering, Handan 430068, China.
Nutrients. 2020 May 13;12(5):1399. doi: 10.3390/nu12051399.
It is widely reported how betaine addition regulates lipid metabolism but how betaine affects cholesterol metabolism is still unknown. This study aimed to investigate the role of betaine in hepatic cholesterol metabolism of Sprague-Dawley rats. Rats were randomly allocated to four groups and fed with a basal diet or a high-fat diet with or without 1% betaine. The experiment lasted 28 days. The results showed that dietary betaine supplementation reduced the feed intake of rats with final weight unchanged. Serum low-density-lipoprotein cholesterol was increased with the high-fat diet. The high-fat diet promoted cholesterol synthesis and excretion by enhancing the HMG-CoA reductase and ABCG5/G8, respectively, which lead to a balance of hepatic cholesterol. Rats in betaine groups showed a higher level of hepatic total cholesterol. Dietary betaine addition enhanced cholesterol synthesis as well as conversion of bile acid from cholesterol by increasing the levels of HMGCR and CYP7A1. The high-fat diet decreased the level of bile salt export pump, while dietary betaine addition inhibited this decrease and promoted bile acid efflux and increased total bile acid levels in the intestine. In summary, dietary betaine addition promoted hepatic cholesterol metabolism, including cholesterol synthesis, conversion of bile acids, and bile acid export.
有大量报道称甜菜碱可调节脂代谢，但甜菜碱如何影响胆固醇代谢尚不清楚。本研究旨在探讨甜菜碱在 Sprague-Dawley 大鼠肝脏胆固醇代谢中的作用。大鼠随机分为 4 组，分别给予基础饲料或高脂肪饲料加或不加 1%甜菜碱。实验持续 28 天。结果表明，饲粮添加甜菜碱可减少大鼠的采食量，但终重不变。血清低密度脂蛋白胆固醇随高脂肪饮食而升高。高脂肪饮食分别通过增强 HMG-CoA 还原酶和 ABCG5/G8 促进胆固醇合成和排泄，从而维持肝脏胆固醇平衡。甜菜碱组大鼠肝总胆固醇水平较高。饲粮添加甜菜碱通过增加 HMGCR 和 CYP7A1 的水平，增强胆固醇合成和胆汁酸由胆固醇转化。高脂肪饮食降低胆盐输出泵水平，而饲粮添加甜菜碱抑制这种降低，促进胆汁酸外排，增加肠道总胆汁酸水平。综上所述，饲粮添加甜菜碱可促进肝脏胆固醇代谢，包括胆固醇合成、胆汁酸转化和胆汁酸输出。
