Masur F, Benesch F, Pfannkuche H, Fuhrmann H, Gäbel G
Institute of Veterinary Physiology, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, 04103, Germany.
Institute of Veterinary Physiology, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, 04103, Germany.
J Dairy Sci. 2016 Apr;99(4):3081-3095. doi: 10.3168/jds.2015-10042. Epub 2016 Feb 1.
Conjugated linoleic acids (CLA), particularly cis-9,trans-11 (c9t11) and trans-10,cis-12 (t10c12), are used as feed additives to adapt to constantly increasing demands on the performance of lactating cows. Under these feeding conditions, the rumen wall, and the rumen epithelial cells (REC) in particular, are directly exposed to high amounts of CLA. This study determined the effect of CLA on the fatty acid (FA) metabolism of REC and expression of genes known to be modulated by FA. Cultured REC were incubated with c9t11, t10c12, and the structurally similar FA linoleic acid (LA), oleic acid (OA), and trans-vaccenic acid (TVA) for 48 h at a concentration of 100 µM. Cellular FA levels were determined by gas chromatography. Messenger RNA expression levels of stearoyl-CoA desaturase (SCD) and monocarboxylate transporter (MCT) 1 and 4 were quantified by reverse transcription-quantitative PCR. Fatty acid evaluation revealed significant effects of CLA, LA, OA, and TVA on the amount of FA metabolites of β-oxidation and elongation and of metabolites related to desaturation by SCD. The observed changes in FA content point (among others) to the ability of REC to synthesize c9t11 from TVA endogenously. The mRNA expression levels of SCD identified a decrease after CLA, LA, OA, or TVA treatment. In line with the changes in mRNA expression, we found reduced amounts of C16:1n-7 cis-9 and C18:1n-9 cis-9, the main products of SCD. The expression of MCT1 mRNA increased after c9t11 and t10c12 treatment, and CLA c9t11 induced an upregulation of MCT4. Application of peroxisome proliferator-activated receptor (PPAR) α antagonist suggested that activation of PPARα is involved in the changes of MCT1, MCT4, and SCD mRNA expression induced by c9t11. Participation of PPARγ in the changes of MCT1 and SCD mRNA expression was shown by the application of the respective antagonist. The study demonstrates that exposure to CLA affects both FA metabolism and regulatory pathways within REC.
共轭亚油酸（CLA），特别是顺-9，反-11（c9t11）和反-10，顺-12（t10c12），被用作饲料添加剂，以适应对泌乳奶牛生产性能不断增长的需求。在这些饲养条件下，瘤胃壁，特别是瘤胃上皮细胞（REC），直接暴露于大量的CLA中。本研究确定了CLA对REC脂肪酸（FA）代谢以及已知受FA调节的基因表达的影响。将培养的REC与c9t11、t10c12以及结构相似的FA亚油酸（LA）、油酸（OA）和反式vaccenic酸（TVA）以100μM的浓度孵育48小时。通过气相色谱法测定细胞内FA水平。通过逆转录定量PCR定量硬脂酰辅酶A去饱和酶（SCD）和单羧酸转运蛋白（MCT）1和4的信使RNA表达水平。脂肪酸评估显示CLA、LA、OA和TVA对β-氧化和延长的FA代谢产物以及与SCD去饱和相关的代谢产物的量有显著影响。观察到的FA含量变化（除其他外）表明REC具有从TVA内源性合成c9t11的能力。SCD的mRNA表达水平在CLA、LA、OA或TVA处理后降低。与mRNA表达变化一致，我们发现SCD的主要产物顺-9 C16:1n-7和顺-9 C18:1n-9的量减少。c9t11和t10c12处理后MCT1 mRNA表达增加，CLA c9t11诱导MCT4上调。过氧化物酶体增殖物激活受体（PPAR）α拮抗剂的应用表明，PPARα的激活参与了c9t11诱导的MCT1、MCT4和SCD mRNA表达的变化。相应拮抗剂的应用表明PPARγ参与了MCT1和SCD mRNA表达的变化。该研究表明，暴露于CLA会影响REC内的FA代谢和调节途径。
