Effect of dietary polyunsaturated fatty acid and antioxidant supplementation on the transcriptional level of genes involved in lipid and energy metabolism in swine

Porcine fat traits depend mostly on the interaction between nutritional and genetic factors. However, the pathways and biological processes influenced by this interaction are still poorly known in pigs, although they can have a huge impact on meat quality traits. The present research provides new knowledge insight into the effect of four diets (D1 = standard diet; D2 = linseed supplementation; D3 = linseed, vitamin E and selenium supplementation; D4 = linseed and plant-derived polyphenols supplementation) on the expression of 24 candidate genes selected for their role in lipid and energy metabolism. The data indicated that 10 out of 24 genes were differentially expressed among diets, namely ACACA, ADIPOQ, ADIPOR1, CHREBP (MLXPL), ELOVL6, FASN, G6PD, PLIN2, RXRA and SCD. Results from the univariate analysis displayed an increased expression of ACACA, ADIPOQ, ADIPOR1, CHREBP, ELOVL6, FASN, PLIN2, RXRA and SCD in D4 compared to D2. Similarly, ACACA, ADIPOQ, ADIPOR1, ELOVL6 and SCD were highly expressed in D4 compared to D3, while no differences were observed in D2-D3 comparison. Moreover, an increased expression of G6PD and ELOVL6 genes in D4 compared to D1 was observed. Results from the multivariate analysis confirmed that D2 was not different from D3 and that ACACA, SCD and FASN expression made D4 different from D2 and D3. Comparing D4 and D1, the expression levels of ELOVL6 and ACACA were the most influenced. This research provides evidence that the addition of both n-3 PUFA and polyphenols, derived from linseed, grape-skin and oregano supplementation in the diets, stimulates the expression of genes involved in lipogenesis and in oxidative processes. Results evidenced a greater effect on gene expression of the diet added with both plant extracts and n-3 PUFA, resulting in an increased expression of genes coding for fatty acid synthesis, desaturation and elongation in pig Longissimus thoracis muscle.

猪脂肪性状主要由营养与遗传因素的交互作用决定。尽管这类交互作用对肉品质性状具有重大影响，但目前学界对猪体内受其调控的分子通路及生物学过程仍知之甚少。本研究针对四种日粮（D1=标准日粮；D2=亚麻籽补充饲喂；D3=亚麻籽+维生素E与硒补充饲喂；D4=亚麻籽+植物源多酚补充饲喂），对24个因参与脂质与能量代谢而被筛选出的候选基因的表达情况进行分析，为阐明日粮对基因表达的调控效应提供了新的认知视角。研究数据显示，24个候选基因中有10个在不同日粮间呈现差异表达，分别为ACACA、ADIPOQ、ADIPOR1、CHREBP（MLXPL）、ELOVL6、FASN、G6PD、PLIN2、RXRA及SCD。单变量分析结果表明，相较于D2组，D4组中ACACA、ADIPOQ、ADIPOR1、CHREBP、ELOVL6、FASN、PLIN2、RXRA与SCD的表达量均显著上调；同样，相较于D3组，D4组中ACACA、ADIPOQ、ADIPOR1、ELOVL6及SCD的表达量显著升高，而D2与D3组间未观察到显著差异。此外，相较于D1组，D4组中G6PD与ELOVL6的表达量显著上调。多变量分析结果进一步证实，D2组与D3组的基因表达模式无显著差异，且ACACA、SCD与FASN的表达差异是导致D4组与D2、D3组产生区分的核心因素；对比D4组与D1组时，ELOVL6与ACACA的表达变化最为显著。本研究证实，在日粮中添加亚麻籽来源的n-3多不饱和脂肪酸与多酚（结合葡萄皮、牛至来源的提取物），可激活参与脂肪生成与氧化过程的基因的表达。结果表明，同时添加植物提取物与n-3多不饱和脂肪酸的日粮对猪背最长肌的基因表达调控效应最强，可上调参与脂肪酸合成、去饱和及延伸过程的基因的表达水平。