Abstract: Objective To study the pulmonary toxic effect of fine particulate matter（PM_2.5） on rats of different gender by acute exposure to PM_2.5 by tracheal instillation. Methods SD rats of SPF grade were randomly divided into saline control group,PM_2.5 high,medium and low dose（PM_2.5 powder dry weight of 13.5,4.5,1.5 mg/kg） groups. After tracheal instillation for seven days,dissected and calculated the lung organ coefficient. The changes of malondialdehyde（MDA）,superoxide dismutase（SOD）,total protein（TP） and albumin（ALB） were detected, and hematoxylin and eosin（HE） staining were used to observe the pathological changes of lung tissue. Results The coefficien to flung organs in each group increased with the increase of exposure dose,and the differences between the high-dose group of female mice[（0.758±0.263）%] and the control group[（0.530±0.026）%],the low-dose group of male mice[（0.476±0.049）%] and the female mice[（0.565±0.057）%] were statistically significant（both P<0.05）.Compared with the control group,the MDA content of female mice increased with the increase of PM_2.5 dose（P<0.05）. There was a statistically significant difference in MDA content between female mice in the high-dose group[（1.159±0.162）nmol/mgprot] and male mice[（0.865±0.155）nmol/mgprot]（P<0.05）. The TP content of male mice in the medium and high dose groups[（0.264±0.069）,（0.396±0.124）g/L] was lower than that of female mice at the same dose[（0.508±0.219）,（0.812±0.140）g/L]（both P<0.05）. The ALB content in the middle dose group[（1.009±0.970）g/L] and high dose group[（1.479±0.874）g/L] of female mice increased compared to the same sex control group[（0.219±0.141）g/L]（P<0.05）,while the ALB content in the high dose group of male mice[（0.840±0.278）g/L] increased compared to the same sex control group[（0.253±0.185）g/L]（P<0.01）. HE staining showed that with the increase of exposure dose,the alveolar wall of rats gradually thickened,and large areas of alveolar consolidation appeared in the medium and high dose groups,with female mice having more severe lesions than male mice. Conclusion Acute exposure to PM_2.5 can cause oxidative stress damage to rat lung tissue,damage alveolar epithelium,and change pulmonary capillary permeability,with gender differences in this type of damage.

Key words: PM_2.5, Intratracheal infusion, Oxidative stress, Acute exposure