A Morphological Study Of Dimethylnitrosamine-induced Liver Fibrosis In Rats

Objective To investigate the pathological features at different two timesin hepatic fibrosis induced by Dimethylnitrosamine(DMN) in rats.Methods The liver fibrotic model was induced by intraperitoneal injectionof 1% DMN for 4 weeks in rats. The following indexes were observed at end of fourth week and other thirth week after stopping intoxication; Serum alanine aminotransferase (ALT) , aspartate aminotransferase (AST) ,Totalprotein(TP) and Total cholestrol(TCH) were determined. The liver/body weight ratio and pathological changes of hepatic tissue were observed at the two different times. Direct red staining was used to determine the area of collageneous fibers by colcor image analysis system. ED1 and α —SMA expression were detected by immunohistochemical staining.Results Compared with the control group, the liver function was obviouslyabnormal in the model group, The loves of ALT, AST and TC content were significantly increased at the fourth week and got its higher at the after thirth week. TP content significantly decreased at the fourth week and no changes at the after thirth week. The liver/body weigh ratio was significantly decreased at two different times in model goups (P<0. 001) Pathologic changes including inflammatory cell infiltration in the portal areas, widely bleeding, necrosis, and the wide fibrous septa were formed, and diffuse cirrhosis were seen in most cases at the fourth week and which remained obvious at the after thirth week. The ED1 and α-SMA positive cells aggergatedprominently in the fibrotic septa at the two different times in model groups. Conclusion Liver fibrosis model was induced by DMN at short-term and endof 3 weeks after discontinuation of DMN, cirrhosis was sti1 1 present in model group.It is an appropriate animal model for studying the mechanisms of hepatic fibrosis, and may provide a model for screening anti liver fibrotic agents.