The Study Of Therapeutical Effects And Mechanism Of Glycine On Hepatic Fibrosis And Cirrhosis In Rats

Objectives: To investigate the therapeutical effects and mechanism of glycine on hepatic fibrosis and cirrhosis in rats.Methods: The hepatic cirrhosis model of rats had been treated with complex factors (CCl4, alcohol, et al). Forty Wistar rats had been randomly divided into five groups: control group, hepatic fibrosis(HF) group, hepatic cirrhosis(HC) group, hepatic fibrosis treated with glycine group(HF+G) and cirrhosis treated with glycine group(HC+G). The levels of plasma endotoxin, alanine aminotransferase(ALT), serum tumor necrosis factor-α(TNF-α), transforming growth factor-β₁ (TGF-β₁) had been detected. The plasma concentrations of endothelin-1(ET-1), calcitonin gene related peptide(CGRP) and atrial natriuretic polypeptide(ANP) had been examined with radioimmunoassay. The stages of hepatic fibrisis had been defined by stainings HE (haematoxylin-eosin) and VG (van gieson). The expression of hepatocyte growth factor(HGF) in liver had been determined with immunohistochemistry.Result: 1 The modeling of the hepatic cirrhosis of rats:It is confirmed that the 4th weekend is the stage of hepatic fibrosis and the 8th weekend is the stage of hepatic cirrhosis by the liver stainings of HE and VG. The pathological changes are alleviated in HF+G group and HC+G group compare with HF group and HC group, respectively.2 The formation of intestinal endotoxemia(IETM ):The level of plasma endotoxin shows a tendency increasing at 4th, 8th weekend compared with the control. There is a statistical difference between groups of model and control, P<0.01. The level of plasma endotoxin is significantly lower in HF+G group and HC+G group than in HF group and HC group, respectively(P<0.05).3 The levels of serum cytokines and plasma ALT:The levels of serum TNF-αand TGF-β₁ show a tendency to increase gradually at 4th, 8th weekend compared with the control. There is a statistical difference between groups of model and control, P<0.01 or P<0.05. The levels of serum TNF-αand TGF-β₁ were significantly lower in HF+G group and HC+G group than in HF group and HC group, respectively(P<0.05). The level of plasma ALT is significantly higher in HF group and HC group than in control group(P<0.01), lower in HF+G group and HC+G group than in HF group and HC group, respectively(P<0.05).4 The levels of plasma vasoactive substances:The plasma ET-1 is higher in HC group than in control group and HF group (P<0.01,P<0.05 respectively), and is lower in HC+G group than in HC group (P<0.05). The CGRP is higher in HF group and HC group than in control group (P<0.01,P<0.05 respectively), is lower in HF+G group and HC+G group than in HF group and HC group respectively(P<0.05). The ANP is higher in HF+G group and HC+G group than in HF group and HC group, respectively(P<0.01).5 The expression of HGF in liver tissues:The expression of HGF in HF group and HC group is significantly higher than in control group(P<0.01,P<0.05), but in HC group is lower than in HF group(P<0.05), and in HF+G group and HC+G group is higher than both HF group and HC group respectively(P<0.05).6 The results of correlation analysis:The result of correlation analysis between plasma endotoxin and ALT is positive , r = 0.585, P<0.05.The result of correlation analysis between plasma endotoxin and serum TNF-αis positive , r = 0.779, P<0.01.The result of correlation analysis between plasma endotoxin and serum TGF-β₁ is positive, r = 0.603, P<0.01.The result of correlation analysis between plasma endotoxin and ET-1 is positive, r = 0.556, P<0.05.The result of correlation analysis between plasma endotoxin and CGRP is positive, r = 0.469, P<0.05.The result of correlation analysis between plasma endotoxin and ANP is r = 0.102, P= 0.687. The result of correlation analysis between serum TNF-αand plasma ET-1 is r = 0.431, P= 0.074.The result of correlation analysis between serum TNF-αand plasma CGRP is r = 0.395, P= 0.105.The result of correlation analysis between plasma ET-1 and CGRP is r = 0.136, P= 0.591.The result of correlation analysis between serum TGF-β₁ and liver HGF is positive , r = 0.550, P<0.05.Conclusion: IETM develops in rats with hepatic fibrosis and cirrhosis. From the result of correlation analysis between plasma endotoxin and serum TNF-αwe know that the IETM is related to the change of TNF-αclosely. The results of correlation analysis between the plasma endotoxin and ET-1, between the plasma endotoxin and CGRP indicate that endotoxin can activate Kupffer cell, which synthesizes and secretes TNF-αthat induces the expressions of ET-1 and CGRP. Glycine could reduce the levels of plasma ET-1 and CGRP by antagonizing the biological effects of endotoxin, which play an important role on delaying the formation of portal hypertension and alleviating liver injuries.IETM could activate Kupffer cell and hepatic stellate cell, which synthesizes and secretes many kinds of cytokines such as TNF-αand TGF-βthat promote the formation of hepatic fibrosis and cirrhosis. By early stage of modeling, the denaturation and necrosis of hepatocytes are severer, and the liver tissue expressing HGF to regenerate hepatocytes and repair injuries. In the groups treated with glycine, the higher expression of HGF will inhibit the formation of hepatic fibrosis and cirrhosis and alleviate liver injuries.In conclusion, glycine has some therapeutical effects on the hepatic fibrosis and cirrhosis in rats.