Mechanism of acute lung injury induced by paraquat and the intervention effect of curcumin in rats

Objective To observe the oxidative stress and lipid peroxidation damage in lung of rats with acute paraquat (PQ) poisoning, and investigate the intervention effect of curcumin on it. Methods Totally 120 adult male Sprague-Dauley rats in the study were divided into the control, PQ-poisoned and curcumin-intervened groups (40 rats in each group). Rats in the PQ-poisoned group were intraperitoneally (i.p.) administered with PQ (15 mg/kg). Curcumin 200 mg/kg was injected i.p. at 15 min before administered with PQ (15 mg/kg, i.p.) in rats of the curcumin-intervened group. The same (15 mg/kg, i.p.) in rats of the curcumin-intervened group. The same volume of saline were injected i.p. in rats of the control group. Eight rats from each group were sacrificed at 3 h, 6 h, 24 h, 3 d, and 7 d after poisoning, respectively. The expression of TGF-β1 mRNA in lungs of rats were measured with fluorescence real-time quantitative PCR. The levels of malondialdehyde (MDA), myeloperoxidase (MPO), and superoxide dismutase (SOD) in lung of rats were measured with thiobarbituric acid colorimetric, spectrophotometer colorimetry and xanthine oxidase method, respectively. Pathological changes in lung were observed by light microscope. Results Compared with the control group, TGF-β1 mRNA expression in lung of rats increased significantly at 6 h, 24 h, 3 d, and 7 d after PQ poisoning (F = 136.93, 32.28, 52.01, 30.94; all P < 0.05), the levels of MDA (F = 132.896, 64.988, 30.622, 30.192) and MPO(F = 34.738, 202.578, 122.019, 119.626) increased obviously (all P < 0.05), but the SOD level decreased remarkably in the PQ-poisoned group and curcumin-intervened group (F = 34.738, 202.578, 122.019, 119.626; all P < 0.05). When compared with the PQ-poisoned group, the levels of TGF-β1 mRNA expression, MPO and MDA in lung of rats in the curcumin-intervened group decreased significantly and the level of SOD in the curcumin-intervened group increased statistically at 6 h, 24 h, 3 d, and 7 d after PQ poisoning (all P < 0.05). Conclusions The initiation of oxidative stress and lipid peroxidation of cell membrane may be one of the mechanisms of acute lung injury in rats with PQ poisoning. The curcumin may reduce the lung injury in rats by inhibiting it. Key words: Paraquat poisoning; Oxidative stress; Lung injury; Curcumin; Rat