ObjectiveTo investigate the changes of inflammatory cytokines in bronchoalveolar lavage fluid (BALF) in rats exposed to paraquat (PQ). MethodsAdult healthy SD rats were randomly divided into a control group (n=8) and three experimental groups (PQ in low dosage of 15 mg/kg,medium dosage of 30 mg/kg,and high dosage of 60 mg/kg,n=24 in each group). The rats in three experimental groups were intragastrically administered with PQ,and the rats in the control group were treated with saline by gavage. Two rats in the control group and six rats in three experimental groups were sacrificed on 1st,7th,14th,and 21st day after exposure respectively. BALF was collected for measurement of interleukin-1(IL-1),IL-6,macrophage inflammatory protein-2(MIP-2),monocyte chemoattractant protein-1(MCP-1),and biopterin by ELISA. ResultsThe levels of cytokines in all experimental groups were higher than those in the control group at any time point. In the exposure day 1 to day 14, IL-1 and biopterin levels in BALF increased significantly with the increase in PQ dose. On 14th and 21st day,IL-6 level in BALF increased significantly with the increase in PQ dosage. The levels of IL-1,IL-6,and biopterin in the experimental groups reached the peak on 14th day. On 14th day,the MIP-2 level in BALF of high-dosage group was significantly higher than that of low-dosage and medium-dosage groups (all P<0.05). The level of MCP-1 in the low-dosage group was lower than that in the medium-dosage and high-dosage groups at any time point (P<0.05). ConclusionIL-1,IL-6,MIP-2,MCP-1,and biopterin may play important roles in the development and progression of PQ-induce lung inflammation.