Abstract: 【Objective】The changes of pulmonary pressure, lipid peroxidation and microstructure of pulmonary resistance vessel of low or normal temperature treated broilers were investigated to study the mechanism of pulmonary vascular remodeling and its role in the pathogenesis of pulmonary hypertension syndrome (PHS). 【Method】180 Avian commercial broilers were randomly allocated to two groups at 14-day-old age. The group reared under normal ambient temperature served as control group. Another group was exposed to low ambient temperature to induce PHS. The ratio of right ventricular weight to total ventricular weight (RV/TV) and mean pulmonary artery pressure (mPAP) were continuously surveyed. Blood samples were taken to measure the plasma malonilaldehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels. Lung samples were taken and stained for elastin. The vessel wall area to vessel total area ratio (WA/TA) and mean media thickness in pulmonary arterioles (mMTPA) were measured by using microscopic image analysis software. 【Result】The mPAP, RV/TV ratio and MDA concentration were significantly higher in low temperature treatment group compared with control group. The WA/TA and mMTPA in pulmonary arterioles were significantly increased in low temperature treatment group. Correlation analysis showed that the plasma MDA concentration and mPAP were significantly correlated with WA/TA and mMTPA. 【Conclusion】The results indicated that the promoted lipid peroxidation and pulmonary hypertension in low temperature treated broiler had led to pulmonary vascular remodeling and in turn higher pulmonary artery pressure. These changes seem to be possessed of great importance in the pathologenesis of PHS in broilers induced by low ambient temperature.

Key words: Broiler, Pulmonary hypertension syndrome, Lipid peroxidation, Pulmonary vascular remodeling