De La Torre Anne, Gruffat Dominique, Chardigny Jean-Michel, Sebedio Jean-Louis, Durand Denys, Loreau Olivier, Bauchart Dominique
INRA, Research Unit on Herbivores, Nutrients and Metabolisms Group, Saint-Genès-Champanelle, France.
Reprod Nutr Dev. 2005 Jul-Aug;45(4):441-51. doi: 10.1051/rnd:2005039.
Ruminant products are the major source of CLA for humans. However, during periods of fat mobilization, the liver might play an important role in CLA metabolism which would limit the availability of the latter for muscles and milk. In this context, rumenic acid (cis-9, trans-11 CLA) metabolism in the bovine liver (n = 5) was compared to that of oleic acid (n = 3) by using the in vitro liver slice method. Liver slices were incubated for 17 h in a medium containing 0.75 mM of FA mixture and 55 microM of either [1-(14)C] rumenic acid or [1-(14)C] oleic acid at 37 degrees C under an atmosphere of 95% O(2)-5% CO(2). Rumenic acid uptake by liver slices was twice (P = 0.009) that of oleic acid. Hepatic oxidation of both FA (> 50% of incorporated FA) led essentially to the production of acid-soluble products and to a lower extent to CO(2) production. Rumenic acid was partly converted (> 12% of incorporated rumenic acid) into conjugated C18:3. CLA and its conjugated derivatives were mainly esterified into polar lipids (71.7%), whereas oleic acid was preferentially esterified into neutral lipids (59.8%). Rumenic acid secretion as part of VLDL particles was very low and was one-fourth lower than that of oleic acid. In conclusion, rumenic acid was highly metabolized by bovine hepatocytes, especially by the oxidation pathway and by its conversion into conjugated C18:3 for which the biological properties need to be elucidated.
反刍动物产品是人类CLA的主要来源。然而，在脂肪动员期间，肝脏可能在CLA代谢中发挥重要作用，这会限制CLA向肌肉和乳汁中的供应。在此背景下，通过体外肝切片法比较了牛肝脏（n = 5）中瘤胃酸（顺式-9，反式-11 CLA）与油酸（n = 3）的代谢情况。肝切片在含有0.75 mM脂肪酸混合物和55 μM [1-(14)C]瘤胃酸或[1-(14)C]油酸的培养基中于37℃、95% O(2)-5% CO(2)气氛下孵育17小时。肝切片对瘤胃酸的摄取量是油酸的两倍（P = 0.009）。两种脂肪酸的肝脏氧化（>掺入脂肪酸的50%）主要导致酸溶性产物的产生，在较低程度上导致CO(2)的产生。瘤胃酸部分转化（>掺入瘤胃酸的12%）为共轭C18:3。CLA及其共轭衍生物主要酯化到极性脂质中（71.7%），而油酸优先酯化到中性脂质中（59.8%）。作为VLDL颗粒一部分的瘤胃酸分泌非常低，比油酸低四分之一。总之，瘤胃酸被牛肝细胞高度代谢，尤其是通过氧化途径以及转化为共轭C18:3，其生物学特性有待阐明。
