Cocoa polyphenols and fiber modify colonic gene expression in rats

Cocoa intake has been associated with health benefits, improving cardiovascular function and metabolism, as well as modulating intestinal immune function. The aim of this study was to take an in-depth look into the mechanisms affected by the cocoa intake by evaluating the colonic gene expression after nutritional intervention, and to ascertain the role of the fiber of cocoa in these effects. To achieve this, Wistar rats were fed for 3-weeks with either a reference diet, a diet containing 10% cocoa (C10), a diet based on cocoa fiber (CF) or a diet containing inulin (I). At the end of the study, colon was excised to obtain the RNA to evaluate the differential gene expression by microarray. Results were validated by RT-PCR. The C10 group was the group with most changes in colonic gene expression, most of them down-regulated but a few in common with the CF diet. The C10 diet significantly up-regulated the expression of Scgb1a1 and Scnn1g and down-regulated Tac4, Mcpt2, Fcer1a and Fabp1 by twofold, most of them related to lipid metabolism and immune function. The CF and I diets down-regulated the expression of Serpina10 and Apoa4 by twofold. Similar patterns of expression were found by PCR. Cocoa consumption down-regulated genes related to the immune system (B cell and mast cell functionality), lipid metabolism in the colon tissue. Most of the beneficial effects attributed to cocoa were due not only to its fiber content, but also to the possible contribution of polyphenols and other compounds.可可摄入已被证实与诸多健康益处相关，可改善心血管功能与代谢状态，同时还能调节肠道免疫功能。本研究旨在通过评估营养干预后的结肠基因表达，深入探究可可摄入所影响的生物学机制，并明确可可纤维在上述效应中发挥的作用。为此，本研究将Wistar大鼠随机分为四组，分别饲喂基础对照日粮、含10%可可的日粮（C10）、以可可纤维为核心的日粮（CF）以及含菊粉（inulin，I）的日粮，干预周期为3周。干预结束后，处死大鼠并摘取结肠组织提取总RNA，通过基因芯片（microarray）技术分析差异基因表达谱，并利用逆转录聚合酶链反应（Reverse Transcription Polymerase Chain Reaction，RT-PCR）对检测结果进行验证。其中C10组大鼠的结肠基因表达变化最为显著，多数基因呈现下调趋势，且与CF组存在少量共同的差异表达基因。C10日粮可显著上调Scgb1a1与Scnn1g的表达水平，并将Tac4、Mcpt2、Fcer1a及Fabp1的表达下调两倍，上述基因大多与脂质代谢及免疫功能相关。CF组与I组日粮则可将Serpina10与Apoa4的表达下调两倍。PCR检测结果也呈现了相似的表达模式。可可摄入可下调结肠组织中与免疫系统（B细胞与肥大细胞功能）及脂质代谢相关的基因表达。可可所带来的多数健康益处，不仅与其纤维成分相关，同时也可能得益于多酚类物质及其他活性成分的协同作用。