Exogenous infusion of short-chain fatty acids can improve intestinal functions independently of the gut microbiota

The present experiment was conducted to investigate the effects of exogenously infused short-chain fatty acids (SCFAs) on the growth development and intestinal functions in a germ-free (GF) pig model. Twelve hysterectomy-derived newborn piglets were reared in six sterile isolators. All piglets were hand-fed Co60-γ-irradiated sterile milk powder for 21 d and then were switched to sterile feed for another 21 d. During the second 21-d period, GF piglets (n = 6) were orally infused with 25 mL/kg sterile saline per day, and SCFA piglets (n = 6) were orally infused with 25 mL/kg SCFAs mixture (acetic, propionic, and butyric acids, 45, 15, and 11 mM, respectively) per day. We observed the concentrations of SCFAs in serum and intestine, and the messenger ribonucleic acid (mRNA) abundance of G-protein-coupled receptor-43 in the ileum was increased (P < 0.05) in the SCFA group. Meanwhile, oral infusion of SCFAs enhanced (P < 0.05) the contents of glucagon-like peptide-2 in the jejunum and serum and tended to increase the villi height in the ileum (P < 0.10). Besides, the activities of lipase, trypsin, sucrase, lactase, Na⁺-K⁺-adenosine triphosphatase ([ATPase] P < 0.05), and Ca²⁺-Mg²⁺-ATPase (P < 0.10) were stimulated and the mRNA expressions of solute carrier family 7 (SLC₇A₁) and regeneration protein (REG)-ΙΙΙ γ in the jejunum (P < 0.05) were upregulated in the SCFA group. Additionally, SCFAs infusion downregulated the mRNA abundances of interleukin (IL)-1β and IL-6 in the jejunum, ileum, or colon (P < 0.05) and increased the counts of white blood cell, neutrophils, and lymphocyte in the blood (P < 0.05). Collectively, exogenous infusion of SCFAs might improve intestinal health through promoting intestinal development and absorption function, and enhancing intestinal immune function, and these effects were occur independently of the gut microbiota.