Effects of low ambient temperatures and dietary vitamin C supplementation on pulmonary vascular remodeling and hypoxic gene expression of 21-d-old broilers

摘要

cqvip:The objective of this study was to evaluate the effects of low ambient temperature(LAT) and dietary vitamin C(VC)supplementation on pulmonary vascular remodeling(PVR) and the relative expression of hypoxia inducible factor-1α(HIF-1α),vascular endothelial growth factor(VEGF) and its receptor 2(VEGFR-2) mRNA of lungs in 21-d-old broilers.4001-d-old male Cobb broilers were assigned randomly to 4 treatments as follows for 21 d:1) LAT and a basal diet;2) LAT and a basal diet supplemented with 1 000 mg kg^(-1) VC(LAT+VC);3) normal ambient temperature(NAT) and a basal diet;4) NAT and a basal diet supplemented with 1 000 mg kg^(-1) VC(NAT+VC).Each treatment was composed of 10 replicates of 10 birds per replicate.Samples of lung were collected after the broilers were killed at d 21.LAT increased the ratio of vessel wall area to vessel total area(WA/TA,%) and mean media thickness in pulmonary arterioles(mMTPA,%)(P<0.05).Dietary VC supplementation decreased mMTPA(P<0.05),but had no effect on the WA/TA.LAT increased(P<0.05) the relative mRNA expression of HIF-1α,VEGF and VEGFR-2,while adding VC to the diet could decrease(P<0.05) their relative mRNA expression.A significant positive correlation existed between the level of VEGF mRNA expression and the value of WA/WT(P<0.05) or mMTPA(P<0.05).These results suggested LAT resulted in pulmonary vascular remodeling,and the increase of HIF-1a,VEGF and VEGFR-2 mRNA expression,and dietary VC supplementation can alleviate pulmonary vascular remodeling in broiler by affecting these gene expression.