Abstract: 　Objective To study Smads involved in TGF-β signal transduction at the transcription level during the development of liver fibrosis in BALB/c mice infected by Schistosoma japonicum. Methods BALB/c mice infected with cercariae of S. japonicum were used as liver fibrosis models. Liver specimens were harvested at 8,12,16 and 24 weeks after infection and normal control were sacrificed at the 24th week. A part of the liver specimens were preserved for pathologic examination and the other part was frozen for the detection of mRNA level of Smad 2,Smad 3,Smad 4 and Smad 7. Results The level of Smad 3 mRNA was significantly higher than that of control at the later stage, while the mRNA level of Smad 2 decreased at 12 and at 24 weeks,respectively. No significant difference in the mRNA level of Smad 4 and Smad 7 was observed between the infection group and the control. Conclusion Smad 3 may induce the development of liver fibrosis in mice infected by S. japonicum while Smad 2 may induce the development of liver fibrosis at early stage and inhibit it at later stage.

Key words: Schistosomiasis japonica, Liver fibrosis, Transforming growth factor-β 1, Smad, RT-PCR