Gruffat Dominique, De La Torre Anne, Chardigny Jean-Michel, Durand Denys, Loreau Olivier, Bauchart Dominique
Institut National de la Recherche Agronomique, Research Unit on Herbivores, Nutrients and Metabolisms Group, 63122 Saint Genès-Champanelle, France.
Lipids. 2005 Mar;40(3):295-301. doi: 10.1007/s11745-005-1385-1.
Hepatic metabolism of vaccenic acid (VA), especially its conversion into CLA, was studied in the bovine (ruminant species that synthesizes CLA) and in the rat (model for non-ruminant) by using the in vitro technique of liver explants. Liver tissue samples were collected from fed animals (5 male Wistar rats and 5 Charolais steers) and incubated at 37 degrees C for 17 h under an atmosphere of 95% O2/5% CO2 in medium supplemented with 0.75 mM of FA mixture and with 55 microM [1-14C]VA. VA uptake was about sixfold lower in bovine than in rat liver slices (P< 0.01). For both species, VA that was oxidized to partial oxidation products represented about 20% of VA incorporated by cells. The chemical structure of VA was not modified in bovine liver cells, whereas in rat liver cells, 3.2% of VA was converted into 16:0 and only 0.33% into CLA. The extent of esterification of VA was similar for both animal species (70-80% of incorporated VA). Secretion of VA as part of VLDL particles was very low and similar in rat and bovine liver (around 0.07% of incorporated VA). In conclusion, characteristics of the hepatic metabolism of VA were similar for rat and bovine animals, the liver not being involved in tissue VA conversion into CLA in spite of its high capacity for FA desaturation especially in the rat. This indicates that endogenous synthesis of CLA should take place exclusively in peripheral tissues.
利用肝外植体的体外技术，对牛（能合成共轭亚油酸的反刍动物）和大鼠（非反刍动物模型）中vaccenic酸（VA）的肝脏代谢，尤其是其转化为共轭亚油酸（CLA）的过程进行了研究。从进食的动物（5只雄性Wistar大鼠和5头夏洛来牛）收集肝脏组织样本，并在补充有0.75 mM脂肪酸混合物和55 microM [1-14C]VA的培养基中，于95% O2/5% CO2气氛下在37℃孵育17小时。牛肝脏切片中VA的摄取量比大鼠低约六倍（P<0.01）。对于这两个物种，氧化为部分氧化产物的VA约占细胞摄取VA的20%。在牛肝细胞中VA的化学结构未发生改变，而在大鼠肝细胞中，3.2%的VA转化为16:0，只有0.33%转化为CLA。两种动物物种中VA的酯化程度相似（摄取VA的70-80%）。作为极低密度脂蛋白（VLDL）颗粒一部分的VA分泌非常低，在大鼠和牛肝脏中相似（约为摄取VA的0.07%）。总之，大鼠和牛动物肝脏中VA代谢的特征相似，尽管肝脏特别是大鼠肝脏具有较高的脂肪酸去饱和能力，但肝脏并不参与组织中VA向CLA的转化。这表明CLA的内源性合成应仅在外周组织中发生。
