Experimental Study Of ACE2、Ang(1-7)and Mas Receptor In The Rat Liver Fibrosis Progression

Objective:Observe the changes of angiotensin-converting enzyme2(ACE2) angiotensin(1-7)[Ang-(1-7)、Mas receptor transforming growth factor-β1(TGF-β1) and connective tissue growth factor (CTGF) in the formation of rat hepatic fibrosis, so as to explore the possible antifibrotic mechanism of ACE2-Ang (1-7)-Mas receptor axis.Methods:From36adult male Wistar rats, six were randomly selected as the normal control group, and the remaining30were given subcutaneous injection of40%chronic carbon tetrachloride (CC14) to induce liver fibrosis. For the first time, CC14was given according to the injection of5ml/kg, after that3ml/kg each time and once every three days. Each amount of CC14were adjusted according to body weight of rats. Six were killed, respectively, in the modeling days of15,30,45,60and75. Histopathological study of liver tissue was done with hematoxylin-eosin(HE) and rapid Masson staining. The levels of Ang(1-7) were determined by enzyme-linked immunosorbent assay (ELISA). Western blotting and Real-time PCR was respectively used to detect the expression of ACE2、Mas receptor TGF-β1、CTGF protein and mRNA.Results:(1) Pathological results:With the extension of the modeling time, the degree of liver fibrosis was gradually increasing. Few pseudolobules were saw until the75days in the rat liver.(2) ELISA results of Ang(1-7):Compared to the normal control group, the level of Ang(1-7) were significantly increased in all model group (P<0.01), and showed an upward trend. The difference between the two model groups adjacent to15,30,45,60days was significantly higher. But the level of Ang(1-7) was no significant difference between the75-day model group and the60-day model group.(3) The results of ACE2mRNA and protein:Compared with the normal control group, the expression of ACE2mRNA and protein were increased in every model group (P<0.01). There were differences between the adjacent groups. While ACE2mRNA and protein expression levels decreased from60days to75days (P<0.01).(4) The results of Mas receptor mRNA and protein:Compared to the normal control group, the level of Mas receptor mRNA and protein were significantly increased in all model group (P<0.01). The difference between the two model groups adjacent to15,30,45,60days was significantly higher. But the expression of Mas receptor mRNA and protein had no significant difference between the75-day model group and the60-day model group.(5) The results of TGF-β1mRNA and protein: With the progress of liver fibrosis, both expression levels of TGF-β1mRNA and protein were significantly higher in every model group than normal control group (P<0.01), and presented a gradually rising trend. Differences was found between the adjacent groups.(6) The results of CTGF mRNA and protein: With the progress of liver fibrosis, both expression levels of CTGF mRNA and protein significantly raised in every model group than normal control group (P<O.01), and showed a gradually rising trend. Differences was found between the adjacent groups.Conclusion:At the early stage of liver fibrosis formation, the protective effects of ACE2-Ang(1-7)-Mas receptor axis maybe the organism’s self-protection mechanism. The role of ACE2-Ang(1-7)-Mas receptor axis is weakened late in the hepatic fibrosis. The expression levels of TGF-β1and CTGF gradually increase along with the progress of liver fibrosis.