title: Digital gene-expression profiling analysis of the cholesterol-lowering effects of alfalfa saponin extract on laying hens.
abstract: BACKGROUND
  To prevent cardiovascular disease, people are advised to limit their intake of dietary cholesterol to less than 300 mg/day. Egg consumption has been seriously reduced because of the high levels of cholesterol. The purpose of the present study was to evaluate the cholesterol-lowering effects of alfalfa saponin extract (ASE) in yolk and the molecular mechanisms underlying these effects using digital gene-expression profiling analysis. Liver and ovary tissues were isolated from laying hens fed with ASE for RNA sequencing.
  
  
  RESULTS
  The cholesterol content of the yolks of eggs from hens fed 120 mg/kg ASE declined considerably on day 60. Other groups (60, 240, 480 mg/kg ASE group) also showed decreases, but they were not significant. Digital gene expression generated over nine million reads per sample, producing expression data for least 12,384 genes. Among these genes, 110 genes showed greater than normal expression in the liver and 107 genes showed greater than normal expression in the ovary. Cholesterol 7 alpha-hydroxylase (Cyp7a1) and apolipoprotein H (Apoh), which act in the synthesis of bile acid and cholesterol efflux, showed more expression in the livers of hens given dietary ASE supplementation. In the ovary, levels of very low density lipoprotein receptor (Vldlr), apolipoprotein B (Apob), apovitellenin 1 (ApovldlII) and vitellogenin (VtgI, VtgII and VtgIII) in ovary decreased with dietary ASE supplementation.
  
  
  CONCLUSIONS
  Transcriptome analysis revealed that the molecular mechanisms underlying the cholesterol-lowering effects of ASE were partially mediated by enhancement of cholesterol efflux in the liver and this reduced of cholesterol deposition in the ovary.
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhou
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
authors.forename: Yinghua
authors.initials: Y
authors.lastname: Shi
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Guo
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
authors.forename: Minggen
authors.initials: M
authors.lastname: Liang
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhu
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
authors.forename: Chengzhang
authors.initials: C
authors.lastname: Wang
mesh_terms: D000818:Animals; D002645:Chickens; D002784:Cholesterol / Q000378:metabolism*; D020869:Gene Expression Profiling; D000455:Medicago sativa / Q000378:metabolism*; D010936:Plant Extracts / Q000378:metabolism*; D012503:Saponins / Q000378:metabolism*
chemical_list: D010936:Plant Extracts; D012503:Saponins; D002784:Cholesterol