Preventive Effects Of Total Flavonoids Of Litsea Coreana Level On Fatty Liver Fibrosis And Its Partly Mechanisms Of Action

Nonalcoholic fatty liver disease(NAFLD) is now recognized as the most common type of liver diseases and might lead to important public health problems.This disease, with an unclear natural history,can be severe and is characterized by a wide spectrum of pathological lesions.These lesions closely resemble those induced by alcohol,but were observed in patients without excessive alcohol consumption.With the incidence of fatty liver increasing,fatty liver fibrosis has became the main cause of liver fibrosis. Howerver,for a long time,studies have failed to clearly define the molecular and physiological changes that mediate the presumed transition from liver steatosis to fatty liver fibrosis due to the lack of animal models carry key features of human fatty liver fibrosis.Litsea coreana levevar(also called Hawk Tea),which is distributed in the southern part of China,has been widely used as a health promoting tea for several centuries.Previous study has showed that Hawk Tea has hypolipidemic effect in rats fed with high fat diet.It has been identified that flavonoids are the main chemical components of this plant,which possess antioxidant property.So the use of flavonoids in pharmaceutical preparation seems very attractive.The aim of the present study is to produce a practical and repeatable experimental rat model for fatty liver fibrosis and use this model exploring the preventive effects of total flavonoids of Litsea Coreana Level(TFLC) on fatty liver fibrosis and it's mechanisms of action.The main contents are divided into some sections follows.1.The establishment rat model of fatty liver fibrosis.The rat model of fatty liver fibrosis was induced by high fat emulsion via gavage and injection with 40%CCl₄ hypodermically in a small dose of 2ml/kg.Meanwhile,the control group was control group was fed with high fat emulsion and standard rodent chow aldlibitnm for 4,6 and 8 weeks.Animals were examined for weight gain,serum and liver biochemistry and morphological evalution.The results showed that the serum levels of ALT,AST,HA,LN,Pâ…¢NP,Câ…£and liver Hyp content in model rats were significantly higher than those in the control and normal groups.The histopathological analysis suggested that the fiber in kiernan's space of the model rats hyperplasy and some fibrocyte towards hepatic cells verge.The results of electorn microscope tell the HSC transform into myofibroblast and collagen fibers deposit.RT-PCR analysis showed the expression of a-SMA,Collagen I mRNA was increased and the expression of PPARγmRNA was reduced.These results suggest that the fatty liver fibrosis model is successfully induced in rats by composite factors of feeding high fat emulsion via gavage and injecting 40%CCl₄ hypodermically for 8 weeks.2.Preventive Effects of TFLC on fatty liver fibrosis.The preventive effects of TFLC were evaluated in composite factors induced fatty liver fibrosis model in rat for 8 weeks.TFLC(100,200,400 mg / kg)was administrated via gavage daily at the begin of the experiment.TFLC effectively reduced the composite factors induced elevated liver index,serum ALT,AST,HA,LN,Pâ…¢NP,Câ…£,and liver Hyp content.The histopathological analysis suggested that TFLC reduced the degree of liver fibrosis in rats.These results suggest that TFLC has positively preventive effects on composite factors induced rat fatty liver fibrosis.3.The mechanisms of TFLC prevent composite factors induced fatty liver fibrosis in rats.RT-PCR and Western blot analysis showed after TFLC treated for 8 weeks,not only the elevated expression of a-SMA,Collagenâ… ,TGF-β1 were reduced,but also the depressed expression of PPARγwas increased.Electronic microscope examination suggested the number of activated HSC was decreased.These results suggested the preventive effects of TFLC on fatty liver fibrosis might be suppress the elevated expression of TGF-β1 and increase the depressed expression of PPARγ.4.The mechanisms of TFLC on HSC functionsIn vitro,TFLC effectively repressed abnormally high level of TGF-β1 mRNA and increase level of PPARγmRNA.Western blot analysis showed after TFLC treated the increased expression of HSC TGF-β1 was depressed and the depressed expression of PPARγwas increased.To sum up,a new rat model of fatty liver fibrosis was established by composite factors.This model is more likely to reproduce the key features of fatty liver fibrosi in humans.TFLC has the preventive effects on experimental fatty liver fibrosis model. The results in vivo and in vitro suggested that its mechanism of action minght be down-regulate TGF-β1 and up-regulate PPARγexpression.