[Increased expression of placenta growth factor in lung tissue of paraquat-induced rat pulmonary fibrosis model].

OBJECTIVE: To investigate the dynamic expression of placenta growth factor (PLGF) in the lungs with paraquat (PQ)-induced pulmonary fibrosis. METHODS: Forty-two adult healthy female Sprague-Dawley (SD) rats were randomly divided into two groups: the control group and the PQ group. Each group was divided into three subgroups, seven animals each. The rats in PQ group were treated intragastrically (ig) with PQ (40 mg/kg) and the rats in control group were treated with the same volume of saline at the beginning of the experiment. The animals of model and control group were sacrificed and lungs were harvested on the 7(th), 14(th) and 28th days respectively. A semiquantitative assay of histological examination and hydroxyproline in lung tissues were used to determine the severity of alveolitis and fibrosis. RT-PCR and immunohistochemistry were used to detect the mRNA and protein expression of PLGF. RESULTS: Hydroxyproline contents in lung tissue were significantly increased after PQ administration. Inflammatory cell infiltration and fibrotic scores were more prominent in the model group compared to the control group. Further study showed that PLGF mRNA on day 7, 14 and 28 (1.28 +/- 0.29, 0.80 +/- 0.07, 0.65 +/- 0.13) and positive index of protein expression (2.27 +/- 0.34, 1.78 +/- 0.41, 1.25 +/- 0.69) in the PQ group were all upregulated as compared with those of the control group. CONCLUSION: The PLGF expression in the lung tissue in rats with paraquat-induced pulmonary fibrosis is upregulated.