Study On The Mechanism Of Vitamin C In Alleviating Ascites Syndrome In Broiler Chickens

This study was conducted to investigate the mechanism of vitaminC in alleviating ascites syndrome in broiler chickens.This study consists of two parts.Experiment 1:Molecular mechanism of Vitamin C on the gene expression of HIF-la of broiler pulmonary artery smooth muscle cells under hypoxiaThis experment was conducted to investigate the effects of VC, Dimethyloxalylglycine (DMOG) and hydrogenperoxide (H2O2) on redox state and the gene expression of hypoxia inducible factor-1? (HIF-1?), vascular endothelial growth factor (VEGF) and its receptor 2(VEGFR2) of broiler pulmonary artery smooth muscle cells (PASMC) under hypoxia induced by CoCl2. The results showed that VC (500?mol/L) significantly increased SOD to MDA ratio (P<0.05), and down-regulated the mRNA expression of HIF-la/VEGF/VEGFR2 (P<0.05). H2O2 significantly up-regulated (P<0.05) the mRNA expression of HIF-1?, and VC decreased the cellular oxidative stress induced by H2O2 and reduced the mRNA expression of HIF-1?. DMOG significantly increased SOD to MDA ratio (P<0.05), and down-regulated the mRNA expression of HIF-1 ? and VEGFR2 (P<0.05), but significantly up-regulated the mRNA expression of VEGF (P<0.05). VC coordinated DMOG significantly up-regulated the mRNA expression of HIF-1?/VEGF/VEGFR2 (P<0.05). VC, H2O2 and DMOG markedly up-regulated the mRNA expression of HIF-1?/VEGF/VEGFR2 when they worked together (P<0.01). These results suggested that VC regulated the mRNA expression of hypoxia genes by enhancing the antioxidant level of extracellular matrix and the activeties of proline hydroxylase.Experiment 2:Effect of VC on ascites syndrome in broilers induced by low ambient temperature and intraperitoneal injection of DMOGForty eight 1-d-old AA broilers were randomly assigned to two temperature levels (normal ambient temperature and low ambient temperature),two injection levels of DMOG (0 and 40mg/Kg BW), two levels of VC (0 and 1000 mg/Kg diet) in a 2×2×2 factorial arrangement (6 replicate pens; 1bird/pen). All birds were fed to 14 d of age. Broilers in low ambient temperature (LAT) were raised at 24 to 26? during 1 to 7 d, and at 9 to 11 ? during 8 to 14d, whereas in normal ambient temperature (NAT) broilers were raised at 29 to 31 ? during 1 to 7 d and at 24 to 26? during 8 to 14d. The results showed that LAT and DMOG significantly reduced ADG (P<0.05) at 8-14d in broiler,and improved ADFI (P<0.05), feed conversion ration was significantly decreased(P<0.05); Supplementation of VC significantly (P<0.05) alleviated the negative effects of LAT and DMOG on broilers.LAT and DMOG significantly increased (P<0.05) the heart index (HI) (14d), and VC significantly decreased (P<0.05)HI in broilers induced by LAT. DMOG significantly increased vessel wall area to vessel total area (WA/TA,%) and mean media thickness in pulmonary arterioles (mMTPA,%) (P<0.05), but VC only significantly decreased (P<0.05) WA/TA and mMTPA in broilers induced by LAT. LAT and DMOG significantly reduced (P<0.05) the mRNA expression of peroxisome proliferator-activated receptor y (PPAR) and Proline hydroxylase domain (PHD) in the lung of broilers. Supplement of VC had a trend of increasing the mRNA expression of PHD and PPAR (P<0.1). LAT significantly increased lung cell apoptosis of broilers (P<0.05), and VC significantly reduced the lung cell apoptosis in broilers induced by LAT (P<0.05). Under normal temperature, DMOG and VC significantly increased lung cell apoptosis in broiler (P<0.05).The results indicated that the addition of VC could alleviate AS in broilers induced by LAT and DMOG.