Zeisel S H
Department of Nutrition, School of Public Health, University of North Carolina, Chapel Hill 27599.
J Am Coll Nutr. 1992 Oct;11(5):473-81. doi: 10.1080/07315724.1992.10718251.
Choline is required to make certain phospholipids which are essential components of all membranes. It is a precursor for biosynthesis of the neurotransmitter acetylcholine and also is an important source of labile methyl groups. Much attention has been given to the effect of supplemental choline upon brain function, i.e., enhancement of acetylcholine synthesis and release. In addition, choline supplements administered to rats in utero or shortly after birth permanently after brain function. The mechanisms for this effect is unknown and under investigation at this time. Healthy humans fed diets deficient in choline, and humans fed parenterally have decreased plasma choline concentrations and develop liver dysfunction that is similar to that seen in choline-deficient animals. In experimental animals, fatty liver occurs in choline deficiency because phosphatidylcholine synthesis is required for very low-density lipoprotein secretion. This accumulation of lipids in liver may explain why choline-deficient rats spontaneously develop hepatocarcinoma. We found that choline deficiency was associated with the accumulation of 1,2-diacylglycerol, an activator of protein kinase C. Several lines of evidence indicate that cancers might develop secondary to abnormalities in protein kinase C-mediated signal transduction.
胆碱是合成某些磷脂所必需的，而这些磷脂是所有细胞膜的重要组成成分。它是神经递质乙酰胆碱生物合成的前体，也是不稳定甲基的重要来源。人们对补充胆碱对脑功能的影响，即增强乙酰胆碱的合成和释放，给予了很多关注。此外，在子宫内或出生后不久给大鼠补充胆碱会永久性地影响脑功能。这种作用的机制尚不清楚，目前正在研究中。食用胆碱缺乏饮食的健康人以及接受肠外营养的人血浆胆碱浓度会降低，并出现与胆碱缺乏动物相似的肝功能障碍。在实验动物中，胆碱缺乏会导致脂肪肝，因为极低密度脂蛋白的分泌需要磷脂酰胆碱的合成。肝脏中脂质的这种积累可能解释了胆碱缺乏的大鼠为何会自发发生肝癌。我们发现胆碱缺乏与蛋白激酶C的激活剂1,2 -二酰甘油的积累有关。有几条证据表明，癌症可能继发于蛋白激酶C介导的信号转导异常。
