Previous studies have shown that exogenous short-chain fatty acids (SCFAs) introduction attenuated the body fat deposition in conventional mice and pigs. However, limited studies have evaluated the effects of exogenously introduced SCFAs on the lipid and glucose metabolism independently of the gut microbiota. This study was to investigate the effects of exogenous introduction of SCFAs on the lipid and glucose metabolism in a germ-free (GF) pig model. Twelve hysterectomy-derived newborn pigs were reared in six sterile isolators. All pigs were hand-fed with sterile milk powder for 21 d, then the sterile feed was introduced to pigs for another 21 d. In the second 21-d period, six pigs were orally administrated with 25 mL/kg sterile saline per day and considered as the GF group, while the other six pigs were orally administrated with 25 mL/kg SCFAs mixture (acetic, propionic, and butyric acids, 45, 15, and 11 mmol/L, respectively) per day and regarded as FA group. Orally administrated with SCFAs tended to increase the adiponectin concentration in serum, enhance the CPT-1 activity in longissimus dorsi, and upregulate the ANGPTL4 mRNA expression level in colon (P < 0.10). Meanwhile, the mRNA abundances of ACC, FAS, and SREBP-1C in liver and CD36 in longissimus dorsi of the FA group were decreased (P < 0.05) compared with those in the GF group. Besides, the mRNA expression of PGC-1α in liver and LPL in longissimus dorsi tended to (P < 0.10) upregulate and downregulate respectively in the FA group. Moreover, oral administration of SCFAs tended to increase the protein level of GPR43 (P < 0.10) and decrease the protein level of ACC (P < 0.10) in liver. Also, oral administration of SCFAs upregulated the p-AMPK/AMPK ratio and the mRNA expressions of GLUT-2 and GYS2 in liver (P < 0.05). In addition, the metabolic pathway associated with the biosynthesis of unsaturated fatty acids was most significantly promoted (P < 0.05) by oral administration of SCFAs. Exogenous introduction of SCFAs might attenuate the fat deposition and to some extent improve the glucose control in the pig model, which occurred independently of the gut microbiota.

中文翻译：

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短链脂肪酸可以独立于猪肠道微生物群改善脂质和葡萄糖代谢


先前的研究表明，外源性短链脂肪酸（SCFA）的引入可减少传统小鼠和猪体内的脂肪沉积。然而，有限的研究评估了外源引入的短链脂肪酸 SCFA 对脂质和葡萄糖代谢的影响，而与肠道微生物群无关。本研究旨在探讨外源性引入短链脂肪酸 SCFA 对无菌 (GF) 猪模型脂质和葡萄糖代谢的影响。十二头子宫切除术后的新生猪在六个无菌隔离器中饲养。所有猪均人工喂养无菌奶粉21 d，然后再喂猪无菌饲料21 d。在第二个 21 天期间，六头猪每天口服 25 mL/kg 无菌生理盐水，视为 GF 组，其余 6 头猪口服 25 mL/kg SCFA 混合物（乙酸、丙酸和每日丁酸分别为45、15和11 mmol/L）并视为FA组。口服SCFAs可增加血清脂联素浓度，增强背最长肌CPT-1活性，上调结肠ANGPTL4 mRNA表达水平（P<<0.10）。同时，与GF组相比，FA组肝脏中ACC、FAS和SREBP-1C以及背最长肌中CD36的mRNA丰度降低（P<<0.05）。此外，FA组肝脏PGC-1α和背最长肌LPL mRNA表达分别呈上调和下调趋势（P<<0.10）。此外，口服SCFAs往往会增加肝脏中GPR43的蛋白水平（P< 0.10）并降低ACC的蛋白水平（P< 0.10）。 此外，口服 SCFA 上调 p-AMPK/AMPK 比率以及肝脏中 GLUT-2 和 GYS2 的 mRNA 表达（P < 0.05）。此外，口服 SCFA 对与不饱和脂肪酸生物合成相关的代谢途径的促进最为显着 (P < 0.05)。外源性引入短链脂肪酸可能会减少脂肪沉积，并在一定程度上改善猪模型中的葡萄糖控制，这与肠道微生物群无关。