Zhang S, Wong W W, Hachey D L, Pond W G, Klein P D
USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX.
J Nutr. 1994 May;124(5):717-25. doi: 10.1093/jn/124.5.717.
We studied the effect of dietary cholesterol on tissue cholesterol synthesis in 10 genetically lean pigs using the 2H2O incorporation method. Five pigs were fed a diet containing 0% cholesterol (controls) and five were fed a diet containing 0.5% cholesterol (cholesterol-fed) from d 1 to d 54 of age. From d 30 to d 54, they received 2H2O and cholesterol synthesis was determined by measuring deuterium enrichment in erythrocyte cholesterol. All pigs were killed on d 54 and liver, ileum, jejunum, kidney, adipose tissue, muscle, and cerebrum were collected for measurement of free and esterified cholesterol and of the deuterium content of tissue free cholesterol. In vivo cholesterol synthesis was inhibited by dietary cholesterol as reflected by a decrease in fractional synthesis rate from 16.8 +/- 1.7%/d in controls to 2.3 +/- 1.1%/d in cholesterol-fed pigs. Cholesterol feeding raised cholesterol ester concentration in plasma, liver, and other tissues. Deuterium enrichment of free cholesterol in tissues, such as liver, was reduced from 11.98 +/- 2.82 milli atom percent excess in controls to 1.83 +/- 1.14 in cholesterol-fed pigs. Greater cholesterol intake did not inhibit cholesterol synthesis in the cerebrum. Deuterium enrichment levels of cholesterol in plasma and liver were similar to those in other tissues except for brain, suggesting an equilibration of cholesterol between the liver and most extrahepatic tissues. The control of cholesterol synthesis in brain appears to be independent of that in liver and other tissues of the body.
我们采用2H2O掺入法研究了膳食胆固醇对10头遗传性瘦猪组织胆固醇合成的影响。从1日龄至54日龄，5头猪饲喂含0%胆固醇的日粮（对照组），另外5头猪饲喂含0.5%胆固醇的日粮（胆固醇饲喂组）。从30日龄至54日龄，它们摄入2H2O，并通过测量红细胞胆固醇中的氘富集量来测定胆固醇合成。所有猪在54日龄时宰杀，收集肝脏、回肠、空肠、肾脏、脂肪组织、肌肉和大脑，以测量游离胆固醇和酯化胆固醇以及组织游离胆固醇的氘含量。膳食胆固醇抑制了体内胆固醇合成，这表现为合成率分数从对照组的16.8±1.7%/天降至胆固醇饲喂组的2.3±1.1%/天。饲喂胆固醇提高了血浆、肝脏和其他组织中的胆固醇酯浓度。肝脏等组织中游离胆固醇的氘富集量从对照组的11.98±2.82毫原子百分比过剩降至胆固醇饲喂组的1.83±1.14。较高的胆固醇摄入量并未抑制大脑中的胆固醇合成。血浆和肝脏中胆固醇的氘富集水平与除大脑外的其他组织相似，这表明肝脏与大多数肝外组织之间的胆固醇处于平衡状态。大脑中胆固醇合成的调控似乎独立于身体的肝脏和其他组织。
