Song Jun-Xian, Ren Hui, Gao Yuan-Feng, Lee Chong-You, Li Su-Fang, Zhang Feng, Li Long, Chen Hong
Department of Cardiology, Peking University People's HospitalBeijing, China.
Beijing Key Laboratory of Early Prediction and Intervention of Acute Myocardial Infarction, Peking University People's HospitalBeijing, China.
Front Physiol. 2017 Aug 25;8:602. doi: 10.3389/fphys.2017.00602. eCollection 2017.
The effects of capsaicin on obesity and glucose homeostasis are still controversial and the mechanisms underlying these effects remain largely unknown. This study aimed to investigate the potential relationship between the regulation of obesity and glucose homeostasis by dietary capsaicin and the alterations of gut microbiota in obese diabetic ob/ob mice. The ob/ob mice were subjected to a normal, low-capsaicin (0.01%), or high-capsaicin (0.02%) diet for 6 weeks, respectively. Obesity phenotypes, glucose homeostasis, the gut microbiota structure and composition, short-chain fatty acids, gastrointestinal hormones, and pro-inflammatory cytokines were measured. Both the low- and high-capsaicin diets failed to prevent the increase in body weight, adiposity index, and Lee's obesity index. However, dietary capsaicin at both the low and high doses significantly inhibited the increase of fasting blood glucose and insulin levels. These inhibitory effects were comparable between the two groups. Similarly, dietary capsaicin resulted in remarkable improvement in glucose and insulin tolerance. In addition, neither the low- nor high-capsaicin diet could alter the α-diversity and β-diversity of the gut microbiota. Taxonomy-based analysis showed that both the low- and high-capsaicin diets, acting in similar ways, significantly increased the Firmicutes/Bacteroidetes ratio at the phylum level as well as increased the abundance and decreased the and abundances at the genus level. Spearman's correlation analysis revealed that the abundance was negatively while the and abundances were positively correlated to the fasting blood glucose level and area under the curve by the oral glucose tolerance test. Finally, the low- and high-capsaicin diets significantly increased the fecal butyrate and plasma total GLP-1 levels, but decreased plasma total ghrelin, TNF-α, IL-1β, and IL-6 levels as compared with the normal diet. The beneficial effects of dietary capsaicin on glucose homeostasis are likely associated with the alterations of specific bacteria at the genus level. These alterations in bacteria induced by dietary capsaicin contribute to improved glucose homeostasis through increasing short-chain fatty acids, regulating gastrointestinal hormones and inhibiting pro-inflammatory cytokines. However, our results should be interpreted cautiously due to the lower caloric intake at the initial stage after capsaicin diet administration.
辣椒素对肥胖和葡萄糖稳态的影响仍存在争议，其作用机制也大多未知。本研究旨在探讨膳食辣椒素对肥胖和葡萄糖稳态的调节与肥胖糖尿病ob/ob小鼠肠道微生物群改变之间的潜在关系。将ob/ob小鼠分别给予正常饮食、低辣椒素（0.01%）饮食或高辣椒素（0.02%）饮食，持续6周。测量肥胖表型、葡萄糖稳态、肠道微生物群结构和组成、短链脂肪酸、胃肠激素和促炎细胞因子。低剂量和高剂量辣椒素饮食均未能阻止体重、肥胖指数和李氏肥胖指数的增加。然而，低剂量和高剂量的膳食辣椒素均显著抑制空腹血糖和胰岛素水平的升高。两组之间的这些抑制作用相当。同样，膳食辣椒素使葡萄糖和胰岛素耐受性显著改善。此外，低剂量和高剂量辣椒素饮食均未改变肠道微生物群的α多样性和β多样性。基于分类学的分析表明，低剂量和高剂量辣椒素饮食以相似的方式，在门水平上显著增加了厚壁菌门/拟杆菌门的比例，在属水平上增加了某些菌属的丰度，同时降低了另一些菌属的丰度。Spearman相关性分析显示，某菌属的丰度与空腹血糖水平以及口服葡萄糖耐量试验曲线下面积呈负相关，而另一些菌属的丰度则呈正相关。最后，与正常饮食相比，低剂量和高剂量辣椒素饮食显著增加了粪便丁酸盐和血浆总胰高血糖素样肽-1水平，但降低了血浆总胃饥饿素、肿瘤坏死因子-α、白细胞介素-1β和白细胞介素-6水平。膳食辣椒素对葡萄糖稳态的有益作用可能与属水平上特定细菌的改变有关。膳食辣椒素诱导的这些细菌变化通过增加短链脂肪酸、调节胃肠激素和抑制促炎细胞因子，有助于改善葡萄糖稳态。然而，由于辣椒素饮食给药后初期热量摄入较低，我们的结果应谨慎解读。
