AIM: To test the hypothesis that introduction of antisense TβR Ⅰ and TβR Ⅱ eukaryotic expressing plasmids into a rat model of immunologically induced liver fibrosis might block the action of TGF-β1 and halt the progression of liver fibrosis.METHODS: RT-Nest-PCR and gene recombination techniques were used to construct rat antisense TβR Ⅰ and TβR Ⅱ recombinant plasmids which could be expressed in eukaryotic cells. The recombinant plasmids and empty vector (pcDNA3) were encapsulated by glycosyl-poly-Llysine and then transducted into rats of pig serum-induced liver fibrosis model. Expression of exogenously transfected gene was assessed by North blot, and hepatic expressions of TβR Ⅰ and TβR Ⅱ were evaluated by RTPCR and West blot. We also performed ELISA for serum TGF-β1, hydroxyproline of hepatic tissues, immunohistochemistry for collagen types Ⅰ and Ⅲ, and VG staining for pathological study of the liver tissues.RESULTS: The exogenous antisense TβR Ⅰ and TβR Ⅱ plasmids could be well expressed in vivo, and block mRNA and protein expression of TβR Ⅰ and TβR Ⅱ in the fibrotic liver at the level of mRNA respectively. These exogenous plasmid expressions reduced the level of TGF-β1(antisense TβR Ⅰ group 23.998±3.045 ng/mL, antisense TβR Ⅱ group 23.156±3.131 ng/mL, disease control group 32.960±3.789 ng/mL; F=38.19, 36.73, P＜0.01). Compared with disease control group, the contents of hepatic hydroxyproline (antisense TβR Ⅰ group 0.169±0.015 mg/g liver, antisense TβR Ⅱ group 0.167±0.009 mg/g liver,disease control group 0.296±0.026 mg/g liver; F=14.39,15.48, P＜0.01) and the deposition of collagen types Ⅰ and Ⅲ decreased in the two antisense treatment groups (antisense TβR Ⅰ group, collagen type Ⅰ 669.90±50.67,collagen type Ⅲ 657.29±49.48; antisense TβR Ⅱ group,collagen type Ⅰ 650.26±51.51, collagen type Ⅲ 661.58±55.28;disease control group, collagen type Ⅰ 1209.44±116.60,collagen type Ⅲ 1175.14±121.44; F=15.48 to 74.89, P＜0.01).Their expression also improved the pathologic classification of liver fibrosis models (compared with disease control group, x2=17.14, 17.24, P＜0.01). No difference was found in the level of TGF-β1, the contents of hepatic hydroxyproline and collagen types Ⅰ and Ⅲ and pathologic grade between pcDNA3 control group and disease control group or between the two antisense treatment groups (F =0.11 to 1.06, x2=0.13 to 0.16, P＞0.05).CONCLUSION: Antisense TβR Ⅰ and TβR Ⅱ recombinant plasmids have certain reverse effects on liver fibrosis and can be used as possible candidates for gene therapy.