| The aim of this study was to investigate the changes of hepatic lipid metabolism in ascites broilers, and to establish the model of hepatocyte hypoxia.Exp.1: 216 one-day-old healthy male broilers were randomly assigned to two groups(normal control group and low temperature induced group), with six replicates per group and eighteen birds per replicate, the experiment period was 35 days. Three chickens were randomly selected from each replicate to detect the AS related classic indexes of hematocrit(HCT), ascites heart index(AHI) and peritoneal effusion at days 21 and 35, in order to judge whether the AS model was reproduced successfully. Based on a judgment criteria, 6 broilers from the normal control group were selected as a new control group, and 6 broilers from the low temperature induced group were selected as a new AS group. And then detect the hepatic expression of genes and proteins involved in liver total cholesterol(TC) metabolism. Results:(1) Compared with the control group, the HCT and AHI values were significantly increased(P < 0.01) in the AS group at days 21 and 35, and yellow liquid was observed in the abdominal cavity of the birds.(2) The serum TC content of the AS group was significantly increased(P < 0.01) at day 21, while there was no significant difference in serum TC and liver TC at day 35. Additionally, there was no significant difference in the hepatic m RNA expression of 3-hydroxy-3-methyl-glutaryl-Co A reductase, which is a hepatic TC synthesis related gene, and low-density lipoprotein receptor, apolipoprotein AI, ATP-binding cassette transporter G5 and ATP-binding cassette transporter G8, which are hepatic TC absorption and transportation related genes, at days 21 and 35. The hepatic mRNA expression of hepatic TC decomposition related genes, cholesterol 7α-hydroxylase(CYP7A1) and liver X receptor α and the hepatic CYP7A1 protein expression of the AS group was significantly decreased(P < 0.05) at day 21, but there was no significant difference at day 35.Exp.2: On the basis of successful construction of the AS model, 6 broilers from the normal control group were selected as a new control group, and 6 broilers from the low temperature induced group were selected as a new AS group. And then detect the hepatic expression of genes and proteins in volved in liver triglyceride(TG) metabolism. Results: The liver TG content of the AS group was significantly decreased(P < 0.05) at day 21, while there was no significant difference in serum TG and liver TG at day 35. At day 21, the hepatic mRNA expression of fatty acid synthase(FAS), malic enzyme(ME) and acetyl-Co A carboxylase(ACC), which are TG synthesis related genes, were significantly decreased(P < 0.05), but there was no significant difference in the mRNA expression of apolipoprotein B(Apo B) and the protein expression of microsomal triglyceride transfer protein(MTP), which were involved in TG transportation. At day 35, the m RNA expression of FAS and ApoB, and the protein expression of MTP were significantly decreased(P < 0.05), while there was no significant difference in the mRNA expression of ME and ACC.Exp.3: Hepatocytes of chicken at 18 th embryo days were cultured in different hypoxia conditions(oxygen supply for 9% and 15%) for 24 h, and each hypoxia group is equipped with a normoxia group as control. The cell viabilities were evaluated by CCK-8. Then the cell viabilities in different time points(0, 2, 6, and 12 h) after hypoxia were evaluated, in order to explore the ability of hypoxia tolerance of hepatocytes under different hypoxia conditions. Results:(1) The cell viabilities of the hypoxia groups(oxygen supply was 9%, 15%) were significant decreased(P < 0.05) at 24 h after hypoxia, compared with the normoxia group.(2) In the hypoxia group of 9% oxygen supply, the cell viabilities of hepatocytes were decreased in 2-6 h after hypoxia; while in the hypoxia group of 15% oxygen supply, the cell viabilities of hepatocytes were decreased in 6-12 h after hypoxia.In conclusions, the lipid metabolism changes were more sensitive at the early stage of ascites broilers; the increase of TC in AS broilers may be due to the decrease in the expression of CYP7A1 and LXRα on cholesterol catabolism; the decrease of TG in AS broilers may be due to the decrease in the expression of FAS, ME and ACC on lipogenesis. The cell viabilities were decreased in hypoxia conditions; and the cell viabilities were decreased in 2-6 h after 9% oxygen supply, while the cell viabilities were decreased in 6-12 h after 15% oxygen supply. |
PDF Full Text Request