Alessandri J M, Arfi T S, Thieulin C
IINRA-CRJ, Laboratoire de nutrition et sécurité alimentaire, Jouy-en-Josas, France.
Reprod Nutr Dev. 1990;30(5):551-76.
Alterations in lipids linked to intestinal maturation and enterocyte differentiation were reviewed. The 3 main lipid components of cell membranes, ie cholesterol, phospholipids and glycolipids, were examined. Cell phospholipid content increases from the crypts to the mid-villus, which accounts for membrane development and organelle growth in differentiating cells. Changes in the proportion of phospholipid polar head groups occur in brush border membrane during postnatal maturation of the small intestine. The possibility that phospholipid fatty acid composition in differentiating cells might be altered by dietary lipids is discussed. Cholesterol biosynthesis mainly occurs in crypt and lower villus cells whereas its absorption from luminal content and esterification into lipoproteins occur in upper villus mature cells. Cholesterol cell content increases in mature cells in comparison to immature cells on the one hand, and in the distal by comparison with proximal parts of the intestine on the other. Increasing cholesterol content is generally correlated with decreasing membrane fluidity, which in turn could modulate functional properties of the mucosa. Glycosphingolipids are mainly found in the brush border membrane, which contains 20-30% glycolipids by weight of total lipids. These components tend to reinforce the membrane stability and significantly contribute to the surface properties of epithelial cells. The latter undergo noticeable changes during cell differentiation and postnatal maturation. Significant changes in both the glycosidic and lipophilic parts of glycosphingolipid molecules occur in differentiating cells and are of possible importance in the process of mucosal maturation. It is possible that the addition of a terminal sialic acid (sialyltransferase activity) instead of a terminal galactose (galactosyltransferase) to an endogenous acceptor (lactosylceramide) could constitute an important event in the differentiation process, and may account for the increasing content of hematosides along the intestinal villus of rat. Alterations in lipid counterpart mainly consist of hydroxylation of fatty acids in hematosides during postnatal maturation or in glucosylceramides during cell differentiation. Collectively these intestinal lipid changes may contribute in part to the development of mucosal barrier, selective permeability and functional properties of the mature intestinal mucosa.
本文综述了与肠道成熟和肠上皮细胞分化相关的脂质变化。研究了细胞膜的三种主要脂质成分，即胆固醇、磷脂和糖脂。细胞磷脂含量从隐窝到绒毛中部增加，这与分化细胞的膜发育和细胞器生长有关。在小肠出生后成熟过程中，刷状缘膜中磷脂极性头部基团的比例发生变化。讨论了饮食脂质可能改变分化细胞中磷脂脂肪酸组成的可能性。胆固醇生物合成主要发生在隐窝和绒毛下部细胞，而其从肠腔内容物的吸收以及酯化进入脂蛋白则发生在绒毛上部成熟细胞。一方面，成熟细胞中的胆固醇含量相对于未成熟细胞增加，另一方面，与小肠近端相比，远端的胆固醇含量增加。胆固醇含量的增加通常与膜流动性的降低相关，这反过来又可能调节黏膜的功能特性。糖鞘脂主要存在于刷状缘膜中，按总脂质重量计算，其含量占20%-30%。这些成分倾向于增强膜稳定性，并对上皮细胞的表面特性有显著贡献。后者在细胞分化和出生后成熟过程中发生明显变化。糖鞘脂分子的糖苷部分和亲脂部分在分化细胞中均发生显著变化，这在黏膜成熟过程中可能具有重要意义。在内源性受体（乳糖神经酰胺）上添加末端唾液酸（唾液酸转移酶活性）而非末端半乳糖（半乳糖转移酶）可能是分化过程中的一个重要事件，这可能解释了大鼠肠绒毛中血型糖苷含量的增加。脂质对应物的变化主要包括出生后成熟过程中血型糖苷脂肪酸的羟基化或细胞分化过程中葡萄糖神经酰胺的羟基化。总的来说，这些肠道脂质变化可能部分有助于成熟肠黏膜的黏膜屏障、选择性通透性和功能特性的发展。
