Fig. 1. Microcystin-LR exerts an anti-fibrotic activity in rats with bleomycin-induced pulmonary fibrosis.
Rats were intratracheally instilled with a single dose of bleomycin (5.0 mg/kg) on day 0 and received microcystin-leucine arginine (LR) (20 μg/L) in drinking water starting on day 7 (LR7), 14 (LR14) or 28 (LR28). Rats were euthanized and samples were collected for analysis day 56 after receiving bleomycin intratracheal instillation. a Schematic representation of experimental design is shown. Data of two rats in Bleomycin group were excluded for further analysis due to animal dead. b Body weight gain after bleomycin treatment was calculated and shown as percentage increase over the baseline body weight. Data are expressed as mean ± SEM. *P < 0.05, **P < 0.01 determined by two-way ANOVA with Student–Newman–Keuls (S–N–K) post hoc analysis (treatment effect F4,28 = 15.299, P < 0.000; time effect F7,28 = 478.774, P < 0.000; interaction effect F28,28 = 2.814, P < 0.000). c Lung tissue sections were prepared and subjected to H&E staining and Masson’s trichrome staining. Scale bar: 2000 μm and 100 μm (insets). d The development of lesions revealed by H&E staining (left panel, F4,28 = 6.434, P = 0.001) and Masson’s trichrome (right panel, F4,28 = 29.255, P < 0.000) was scored by pathologists blind to the study design. e Lung tissue collagen content was determined by hydroxyproline analysis (F4,28 = 6.680, P = 0.001). *P < 0.05, **P < 0.01 determined by one-way ANOVA with S-N-K post hoc analysis (d, e). n = 5 (bleomycin) or n = 7 (all the other treatments) rats per group.