Regulative Effect Of Medium-Chain Fatty Acids On Intestinal And Liver Injury Of Piglets After Lipopolysaccharide Challenge

The experiments was conducted to evaluate the beneficial effects of medium-chain fatty acids(MCFA)on intestinal and liver injury caused by lipopolysaccharide(LPS)challenge in weaned piglets.A total of 24 weaned piglets with average body weight 9.0±0.7 kg,were used in a 2x2 factorial design experiments.The two main factors were dietary treatment(corn oil or MCFA)and immunological treatment(sterile saline or LPS).Four treatment groups were:1)5%corn oil+saline,2)4%MCFA+1%corn oil +saline,3)5%corn oil+LPS,and 4)4%MCFA+1%corn oil +LPS,respectively.After feeding with MCFA or corn oil diets for 21 days,the weanling pigs in treatment 3 and 4 were administrated intraperitoneally with LPS at 100 μg/kg body weight,and the piglets in treatment 1 and 2 were administrated with the same amount of sterile saline.Blood samples were obtained at 2 or 4 h after sterile saline or LPS administration,and then the pigs were humanely killed to obtain intestinal and liver samples for determining fatty acid composition,histological structure and function,and mRNA abundance of the key genes in nucleotide binding oligomerization domain protein(NOD)and toll-like receptor 4(TLR4)signaling pathways.1.The experiment was conducted to explore the beneficial role of MCFA on intestinal damage of piglets after LPS challenge.The results showed that:(1)MCFA changed significantly intestinal fatty acid composition.(2)MCFA did not affect growth performance of weanling pigs.(3)MCFA improved intestinal morphology indicated by greater villus height in small intestine(P<0.05).(4)MCFA improved intestinal digestive function indicated by increased activities of maltase and sucrase in jejunum and ileum,and increased activities of alkaline phosphatase in ileum(P<0.05).(5)MCFA reduced the mRNA expression of jejunal TLR4,TNF-α receptor-associated factor 6(TRAF6),NOD2 and receptor-interacting serine/threonine-protein kinase 2(RIPK2),and ileal TRAF6,NOD2 and RIPK2(P<0.05),and tended to reduce the mRNA expression of jejunal nuclear factor-KB(NF-κB)(P=0.09).These results indicate that dietary MCFA supplementation inhibits TLR4 and NOD signaling pathways,and thus relieves the intestinal injury induced by LPS challenge.2.The experiment was conducted to explore the beneficial role of MCFA on hepatic injury of piglets after LPS challenge.The results showed that:(1)Dietary MCFA supplementation changed significantly hepatic fatty acid composition.(2)MCFA alleviated histological liver damage induced by LPS.(3)MCFA improved liver function indicated by lower serum alanine aminotransferase(ALT),aspertate aminotransferase(AST)and alkaline phosphatase(AKP)activities at 2 h and 4 h post-injection(P<0.05).(4)MCFA increased protein expression of hepatic claudin-1(P<0.05).(5)MCFA decreased hepatic mRNA expression of TNF-α,heat shock protein 70(HSP70)and cyclooxygenase 2(COX2)(P<0.05).(6)MCFA down-regulated hepatic mRNA abundance of TLR4,myeloid differentiation factor 88(MyD88),IL-1 receptor-associated kinase 1(IRAK1),TRAF6,suppressor of cytokine signaling 1(SOCS1),p38,Jun-N-terminal kinase(JNK),NOD1,RIPK2,and NF-κB(P<0.05).These results indicate that dietary MCFA addition exerts a protective effect on liver damage associated with inhibition of NOD and TLR4 signaling pathways.