Background： The objective of this study was to characterize the mRNA expression profile related to rumen epithelial inflammation through the in vivo and in vitro experiments. In the in vivo experiment, rumen papillae were collected from four dairy cows adapted to either a 40 % （LC） or 70 % （HC） concentrate feeds for microarray analysis. Results： Results showed that 245 differentially expressed genes （DEGs） were detected in the cows fed the HC relative to the LC diet. The DEGs were first annotated, and results revealed that the expression of inflammation- related genes, including IL-1t8, 1L-2, IL-22, CCL19, CCLS, CX3CR1, CXCL6, INHBE, LEPR, PRL, and TNFRSF9 found in the cytokine-cytokine receptor pathway were up-regulated in the HC-fed cows, indicating local inflammation in the rumen epithelium was triggered. The expression of IL-1~, 1l_-2, and IL-6 was further validated by qRT-PCR. To demonstrate whether there were relationships between cytokine mRNA expression and ruminal factors （pH and LPS）, the isolated ruminal epithelial cells were cultured in vitro. Results showed that the mRNA expression of IL-1, IL-2, IL-6, and IL-8 increased after the LPS treatment, while Iow-pH treatment elevated the mRNA expression of TNF-a, suggesting that Iow-pH coupled with higher levels of LPS in rumen of cows fed the HC may be mainly responsible for the triggered local ruminal inflammation. Conclusions： Our results indicate that ruminal local inflammation response might be triggered during HC feeding and these findings also enhance the knowledge of rumen epithelial adaptation to HC at the molecular level.
Background: It is wel known that peptides play a vital role in the nutrition and health of dairy cows. Bovine oligopeptide transporter 1(bP epT 1) is involved in the peptide transport process in the gastrointestinal tracts of dairy cows. However,little information is known in the characteristics of bP epT 1. Therefore, the purpose of this study was to characterize bP epT 1 functional y using a mammalian cel expression system. The uptake of radiolabeled dipeptide glycyl-sarcosine([3 H]-Gly-Sar)into the bP epT 1-transfected Chinese hamster ovary cel s was measured at various pH and substrate concentrations and with or without 15 other smal peptides that contained Met or Lys.Results: Western blot results showed that the abundance of bP epT 1 protein in the jejunum and ileum are the highest in the gastrointestinal tract of dairy cows. The uptake of [3 H]-Gly-Sar by b Pep T1-Chinese hamster ovary cells was dependent on time, p H, and substrate concentration, with a low Kmvalue of 0.94 ± 0.06 mmol/L and a maximum velocity of 20.80 ± 1.74 nmol/(mg protein · 5 min). Most of the di-and tripeptides were the substrates of b Pep T1,based on substrate-competitive studies. However, bP epT 1 has a higher affinity to the peptides with shorter chains, greater hydrophobicity, and negative or neutral charges.Conclusions: These results demonstrated for the first time the functional characteristics of bP epT 1, and they provide a new insight and better understanding into its vital role in absorbing a wide range of peptides from the digestive tract of dairy cows.
Qingbiao XuZhixuan LiuHongyun LiuFengqi ZhaoXinbei HuangYueming WuJianxin Liu
