Objective  To understand the toxicodynamics of paraquat in rabbits.

  Methods  A total of 20 rabbits were randomly divided into three groups, namely control group(n=6) dosed with 2 mL/kg normal saline by gavage, low dose group(n=6) dosed with 100 mg/kg paraquat, and high dose group(n=8) dosed with 200 mg/kg paraquat. Serum biochemical indexes, cytokines and arterial blood gas were analyzed before dosing and 8 h, 24 h, 72 h, 7 d after administration. Histopathology of lung were implemented after 7 days of exposure.

  Results  In the high dose group, 2 rabbits were died at 35 h and 75 h, respectively(the following data were not included these 2 rabbits). The increase of body mass of the poisoned animals during the observation period was lower than that of the control group(P < 0.05), and there was no significant difference in body mass between two dosed groups(P > 0.05). After 7 days of exposure, there was no significant difference of serum alanine aminotransferase, aspartate aminotransferase, creatine kinase isozyme, lactate dehydrogenase, α-hydroxybutyrate dehydrogenase, urea, creatinine, total protein, albumin and arterial blood gas analysis(P > 0.05). After 7 days of exposure, the levels of serum transforming growth factor β₁(TGF-β₁) in the three groups were increased (P < 0.05), especially in the high dose group. The level of high mobility group protein B1(HMGB1) in high dose group was higher than that in control group and low dose group(P < 0.05). Histopathological examination showed paraquat caused acute lung injury and early pulmonary fibrosis.

  Conclusions  Paraquat poisoning can cause growth restriction, increase levels of some inflammatory factors and cause lung damage. These results can provide a reference for the prognosis of patients with paraquat poisoning, and provide basic data for other animal experiments.