十二指肠内注入溶血磷脂酰胆碱可恢复低锌饮食喂养大鼠对维生素A和E的肠道吸收。

Department of Human Nutrition, Kansas State University, Manhattan 66506, USA.

Exp Biol Med (Maywood). 2001 Apr;226(4):342-8. doi: 10.1177/153537020122600412.

Our previous work has shown that the lymphatic absorptions of lipids and lipid-soluble vitamins, retinol and alpha-tocopherol (alphaTP), are lowered markedly in rats fed a low-zinc (LZ) diet in parallel with lower lymphatic phospholipid outputs. Phosphatidylcholine (PC), when infused enterally, restored the absorptions of fat and retinol, but further lowered the absorption of alphaTP in rats fed the LZ diet. This study was conducted to determine whether a luminal infusion of lysophosphatidylcholine, a product of PC hydrolysis by pancreatic phospholipase A2 (PLA2), would simultaneously restore the absorptions of retinol and alphaTP in LZ rats. Rats were trained to consume two meals per day and were divided into two groups. One group was fed an AIN-93G diet containing a LZ (3.0 mg Zn/kg), and the other was fed the same diet, but containing adequate zinc (AZ; 30.0 mg Zn/kg) for 6 weeks. Rats with lymph cannula were infused at 3.0 ml/hr for 8 hr with a lipid emulsion containing retinol, alphaTP, and 14C-labeled triolein (14C-oleic acid) with or without 1-oleoyl-2-hydroxy phosphatidylcholine (lysoPC) in 24 ml of PBS (pH 6.5). When the lipid emulsion without lysoPC was infused, the absorptions of retinol and alphaTP were significantly lower in LZ rats (retinol, 13.2+/-1.5 nmol; alphaTP, 430.6+/-66.8 nmol) than in AZ rats (retinol, 18.2+/-1.0 nmol; alphaTP, 543.8+/-58.9 nmol). The lower absorptions of the vitamins in LZ rats occurred in parallel with a significant decrease in 14C-oleic acid absorption. When the emulsion containing lysoPC was infused, however, absorptions of the vitamins (retinol, 18.4+/-3.0 nmol; alphaTP, 777.2+/-92.1 nmol) in LZ rats were restored completely to the control levels (retinol, 20.4+/-2.8 nmol; alphaTP, 756.3+/-136.1 nmol). The results suggest that the luminal hydrolysis of PC to lysoPC by PLA2 may be impaired in LZ rats, resulting in impaired absorption of fat and the fat-soluble vitamins.

我们之前的研究表明，在喂食低锌（LZ）饮食的大鼠中，脂质以及脂溶性维生素（视黄醇和α-生育酚（αTP））的淋巴吸收显著降低，同时淋巴磷脂输出也较低。当肠内注入磷脂酰胆碱（PC）时，可恢复脂肪和视黄醇的吸收，但却进一步降低了喂食LZ饮食大鼠中αTP的吸收。本研究旨在确定通过胰腺磷脂酶A2（PLA2）水解PC产生的溶血磷脂酰胆碱进行肠腔注入，是否能同时恢复LZ大鼠中视黄醇和αTP的吸收。大鼠被训练为每天进食两餐，并分为两组。一组喂食含有低锌（3.0毫克锌/千克）的AIN-93G饮食，另一组喂食相同饮食，但含有充足锌（AZ；30.0毫克锌/千克），持续6周。对带有淋巴插管的大鼠，以3.0毫升/小时的速度持续8小时注入含视黄醇、αTP和14C标记的三油精（14C-油酸）的脂质乳剂，该脂质乳剂溶解于24毫升pH值为6.5的磷酸盐缓冲液（PBS）中，且添加或不添加1-油酰基-2-羟基磷脂酰胆碱（溶血PC）。当注入不含溶血PC的脂质乳剂时，LZ大鼠中视黄醇和αTP的吸收（视黄醇，13.2±1.5纳摩尔；αTP，430.6±66.8纳摩尔）显著低于AZ大鼠（视黄醇，18.2±1.0纳摩尔；αTP，543.8±58.9纳摩尔）。LZ大鼠中维生素吸收较低与14C-油酸吸收的显著降低同时出现。然而，当注入含溶血PC的乳剂时，LZ大鼠中维生素的吸收（视黄醇，18.4±3.0纳摩尔；αTP，777.2±92.1纳摩尔）完全恢复到对照水平（视黄醇，20.4±2.8纳摩尔；αTP，756.3±136.1纳摩尔）。结果表明，在LZ大鼠中，PLA2将PC水解为溶血PC的肠腔水解过程可能受损，从而导致脂肪和脂溶性维生素吸收受损。