Objective To investigate the role of fibronectin(FN) receptor α 5β 1 in liver fibrosis Methods Northern blot analysis and immuno~histochemical techniques were used to observe changes in the expression of FN and FN receptor α 5β 1 on hepatic stellate cells (HSCs) in vivo and in vitro of rat liver fibrosis induced by CCl 4 Results (1) α 5β 1 was mainly detected in the endothelia and some of the desmin(DM) positive cells of the sinusoids in normal rat liver The expression of α 5β 1 of DM positive cells detected by immunohistochemistry reached its peak at the 10th week of the experiment The changes in FN expression were similar to that of α 5β 1 (2) The expression of FN, α 5 and β 1 mRNAs in the experimental group was remarkably increased especially at the 6th week, compared to that of normal liver specimens The expression of the three mRNAs of HSCs in vitro isolated from the experimental group (6 weeks) was higher than those from normal liver (3) The expression of FN, α 5 and β 1 mRNAs increased in normal rat HSCs after treatment with transforming growth factor β 1 (TGF β 1) for 2 hours After 4 hours of treatment, the expression of the three mRNAs fell to levels similar to the control group Immunocytochemistry revealed that the expression of α 5β 1 of HSCs reached its peak after 4 hours of treatment with TGF β 1 and dropped to normal 2 hours later Conclusion These data suggest that HSCs normally express FN receptor α 5β 1 The activation of HSCs during liver fibrogenesis leads to an increase of FN, α 5 and β 1 mRNA expression The expression of FN and α 5β 1 of HSCs in vitro is up regulated by TFG α 5β 1 The detection of gene transcription of FN and its receptor by Northern blot analysis suggests the activation and proliferation of HSCs and thereby provides a sensitive signal of liver fibrosis Objective To investigate the role of fibronectin (FN) receptor α 5β 1 in liver fibrosis Methods Northern blot analysis and immunohistochemistry were used to observe changes in the expression of FN and FN receptor α 5β 1 on hepatic stellate cells (HSCs) in vivo and in vitro of rat liver fibrosis induced by CCl 4 Results (1) α 5β 1 was mainly detected in the endothelia and some of the desmin (DM) positive cells of the sinusoids in normal rat liver The expression of α 5β 1 of DM positive cells detected by immunohistochemistry reached its peak at the 10th week of the experiment The changes in FN expression were similar to that of α 5β 1 (2) The expression of FN, α 5 and β 1 mRNAs in the experimental group was remarkably absorbed at the 6th week, compared to that of normal liver specimens The expression of the three mRNAs of HSCs in vitro isolated from the experimental group (6 weeks) was higher than those from normal liver (3) The expression of FN, α 5 and β 1 mRNAs increased in normal rat HSCs after treatment with transforming growth factor β 1 (TGF β 1) for 2 hours After 4 hours of treatment, the expression of the three mRNAs fell to levels similar to the control group Immunocytochemistry revealed that the expression of α 5β 1 of HSCs reached its peak after 4 hours of treatment with TGF β 1 and dropped to normal 2 hours later These data suggest that HSCs normally express FN receptor α 5β 1 The activation of HSCs during liver fibrogenesis leads to an increase of FN, α 5 and β 1 mRNA expression The expression of FN and α 5β 1 of HSCs in vitro is up regulated by TFG α 5β 1 The detection of gene transcription of FN and its receptor by Northern blot analysis suggests the activation and proliferation of HSCs and provided a sensitive signal of liver fibrosis