title: Lipopolysaccharide derived from the digestive tract activates inflammatory gene expression and inhibits casein synthesis in the mammary glands of lactating dairy cows.
abstract: To meet the nutrition requirements of lactation, dairy cows are usually fed a high concentrate diet (HC). However, high-grain feeding causes subacute ruminal acidosis (SARA), a metabolic disorder that causes milk protein depression. This study aimed to investigate the effect of lipopolysaccharide (LPS) released in the rumen on inflammatory gene expression and casein synthesis in mammary glands of lactating dairy cows fed a HC diet. We found that milk protein was significantly decreased in the HC group after 15 weeks of feeding. Overall, LPS concentrations in the rumen fluid, lacteal artery and vein were increased in the HC group. Transcriptome microarray was used to evaluate alterations in the signaling pathway in mammary glands. Signaling pathways involved in inflammatory responses were activated, whereas those involved in protein synthesis were inhibited in the HC group. mRNA expression involved in inflammatory responses, including that of TLR4, NF-κB and pro-inflammatory genes, was increased in the HC group, while αs1-casein (CSN1S1), β-casein (CSN2), mTOR and S6K gene expression were decreased. Moreover, protein expression was consistent with the corresponding gene expression. After feeding with an HC diet, LPS derived from the rumen increased inflammatory gene expression and inhibited casein synthesis in the mammary glands of lactating dairy cows fed a HC diet.
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, P.R. China.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, P.R. China.
authors.forename: Guangjun
authors.initials: G
authors.lastname: Chang
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, P.R. China.
authors.forename: Tianle
authors.initials: T
authors.lastname: Xu
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, P.R. China.
authors.forename: Lei
authors.initials: L
authors.lastname: Xu
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, P.R. China.
authors.forename: Junfei
authors.initials: J
authors.lastname: Guo
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, P.R. China.
authors.forename: Di
authors.initials: D
authors.lastname: Jin
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, P.R. China.
authors.forename: Xiangzhen
authors.initials: X
authors.lastname: Shen
mesh_terms: D000138:Acidosis / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D002364:Caseins / Q000096:biosynthesis*; D002417:Cattle; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D004032:Diet; D005260:Female; D041981:Gastrointestinal Tract / Q000378:metabolism; D007249:Inflammation / Q000473:pathology; D007774:Lactation / Q000502:physiology*; D008070:Lipopolysaccharides / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000378:metabolism*; D008894:Milk Proteins / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism
chemical_list: D002364:Caseins; D016207:Cytokines; D008070:Lipopolysaccharides; D008894:Milk Proteins; D016328:NF-kappa B; D051197:Toll-Like Receptor 4; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; C448959:ribosomal protein S6 kinase, 70kD, polypeptide 2
keywords: Immune response; Immunity; Immunology and Microbiology Section; casein; inflammatory response; lipopolysaccharide; mammary gland; signaling pathway