Zhou Hua, Yu Bing, Sun Jing, Liu Zuohua, Chen Hong, Ge Liangpeng, Chen Daiwen
Key Laboratory of Animal Disease-Resistance Nutrition, Chengdu, 611130, Sichuan, China.
Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China.
J Anim Sci Biotechnol. 2021 May 6;12(1):61. doi: 10.1186/s40104-021-00581-3.
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.
先前的研究表明，外源性引入短链脂肪酸（SCFAs）可减少常规小鼠和猪的体脂沉积。然而，仅有有限的研究评估了外源性引入SCFAs对脂质和葡萄糖代谢的影响，且未考虑肠道微生物群的作用。本研究旨在探讨在无菌（GF）猪模型中外源性引入SCFAs对脂质和葡萄糖代谢的影响。
12头通过子宫切除术获得的新生仔猪饲养于6个无菌隔离器中。所有仔猪人工饲喂无菌奶粉21天，之后再引入无菌饲料21天。在第二个21天期间，6头仔猪每天口服25 mL/kg无菌生理盐水，作为GF组；另外6头仔猪每天口服25 mL/kg SCFAs混合物（乙酸、丙酸和丁酸，浓度分别为45、15和11 mmol/L），作为FA组。
口服SCFAs有增加血清脂联素浓度、增强背最长肌中肉碱棕榈酰转移酶-1（CPT-1）活性以及上调结肠中血管生成素样蛋白4（ANGPTL4）mRNA表达水平的趋势（P < 0.10）。同时，与GF组相比，FA组肝脏中乙酰辅酶A羧化酶（ACC）、脂肪酸合酶（FAS）和固醇调节元件结合蛋白-1C（SREBP-1C）以及背最长肌中脂肪酸转运蛋白36（CD36）的mRNA丰度降低（P < 0.05）。此外，FA组肝脏中过氧化物酶体增殖物激活受体γ辅激活因子1α（PGC-1α）的mRNA表达有上调趋势（P < 0.10），而背最长肌中脂蛋白脂肪酶（LPL）的mRNA表达有下调趋势（P < 0.10）。而且，口服SCFAs有增加肝脏中G蛋白偶联受体43（GPR43）蛋白水平的趋势（P < 0.10），并降低ACC蛋白水平（P < 0.10）。此外，口服SCFAs上调了肝脏中磷酸化腺苷酸活化蛋白激酶（p-AMPK）与AMPK的比值以及葡萄糖转运蛋白2（GLUT-2）和糖原合成酶2（GYS2）的mRNA表达（P < 0.05）。另外，口服SCFAs最显著促进了与不饱和脂肪酸生物合成相关的代谢途径（P < 0.05）。
外源性引入SCFAs可能减少猪模型中的脂肪沉积，并在一定程度上改善血糖控制，且这一过程独立于肠道微生物群发生。
