Digestion and assimilation features of dietary DAG in the rat small intestine
Digestion and assimilation features of dietary DAG in the rat small intestine
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DOI：
10.1007/s11745-003-1027-7
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发表时间：
2003-01-01
期刊：
影响因子：
1.9
通讯作者：
Tokimitsu, I
中科院分区：
文献类型：
--
作者：
Kondo, H;Hase, T;Tokimitsu, I
最近的一些研究表明，与TAG油相比，富含1,3种的DAG油可以抑制餐后血清TAG水平的升高，减少体脂积累。为了阐明DAG有益作用的机制，我们研究了DAG在小肠中与管腔消化途径和粘膜中tag合成途径相关的代谢特征。以乳状液灌胃时，TAG被消化为1,2- dag、2-MAG和FFA，而1,3d - ag被消化为1(3)-MAG和FFA。通过脂质中[1-C-14]亚油酸的掺入来评估，与TAG输注相比，DAG输注显著降低了粘膜TAG-合成。然而，dag灌胃后大鼠粘膜1,3- dag的合成明显增加。与TAG组相比，DAG组大鼠粘膜1,3-DAG的总量也增加了4.5倍。接下来，我们研究了1,3- dag的合成途径。在外翻肠囊的培养中，1,3- dag的产生需要1-MAG的存在，这表明在注射了dag的大鼠中，1,3- dag的合成是由于1(3)-MAG的酰化。此外，对DAG酰基转移酶活性的测定表明，1,3-DAG在TAG合成中很少被利用。这些结果表明，1,3-DAG在肠道的消化和同化特征可能是膳食DAG降低餐后血清TAG水平的原因。
Several recent studies have demonstrated that dietary DAG oil rich in 1,3-species suppresses the postprandial increase of serum TAG level and decreases body fat accumulation, compared with TAG oil. To clarify the mechanisms underlying the beneficial effects of DAG, we investigated the metabolic features of DAG in the small intestine with regard to the digestion pathway in the lumen and the TAG-synthesis pathway in the mucosa. When intraduodenally infused as an emulsion, TAG was digested to 1,2-DAG, 2-MAG, and FFA, whereas 1,3D-AG was digested to 1(3)-MAG and FFA. When assessed by the incorporation of [1-C-14] linoleic acid in lipids, the mucosal TAG-synthesis was significantly reduced by DAG infusion compared with TAG infusion. However, the mucosal 1,3-DAG synthesis was remarkably increased in the DAG-infused rats. The total amount of mucosal 1,3-DAG was also increased (4.5-fold) after DAG infusion compared with that after TAG infusion. Next, we examined the synthesis pathway of 1,3-DAG. In cultures of the everted intestinal sacs, 1,3-DAG production required the presence of 1-MAG, suggesting that the 1,3-DAG synthesis was due to acylation of 1(3)-MAG in the DAG-infused rats. Furthermore, measurements of DAG acyltransferase activity indicated that 1,3-DAG was little utilized in TAG synthesis. These findings suggest that features of 1,3-DAG digestion and assimilation in the intestine may be responsible for the reduction of the postprandial serum TAG level by dietary DAG.