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

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.