| Objective:we use an animal model induced by AFB1 which was established in the 80 times by our institute to explore the best dose of diethylnitrosamine(DEN) and 2-acetylaminofluorene,which can induce liver cancer of rats.we study the anti-tumor effect and its mechanisms of different concentration Camellia chrysantha(Hu)Tuyama and it's flower in the rat's liver preneoplastic nodules induced by DEN。Methods:1.diethylnitrosamine concentration experiment:The male rats,6 weeks old, were used for establishing a short-term preneoplastic model:37 healthy male wistar rats were divived into four group at random at the bases of diethylmitro samine(DEN)doses of abdomen injection and 2-AAF solution which was mixed into the normal food.9 rats for group A,150mg/kg.bw of DEN and 0.015% 2-AAF,10 rats for group B,100mg/kg.bw of DEN and 0.015%2-AAF;9 rats for group C,150mg/kg.bw of DEN and 0.010%2-AAF;9 rats for group D, 100mg/kg.bw of DEN and 0.010%2-AAF.The rats received DEN by abdomen injection.Then 2-AAF solution which was mixed into the normal food was administered by the rat for two weeks.Two-thirds partial hepatectomy was per formed after seven days for taking 2-AAF to promote tumor process.Stop giving 2-AAF solution food then feeding the normal food two days.Prohibit to give food for 24 hours later all the rats were executed.Five pieces of liver were taken from each rat.The preneoplastic nodules forγ-GT positive foci in liver sections were measured,and the total areas of the positive foci per square centimeter(mm~2/cm~2),the average acreage per positive foci(mm~2/entries),and the amount of positive foci per square centimeter(entries/cm~2)were calculated respectively.2.Camellia chrysantha(Hu)Tuyama experiment:The male rats,6 weeks old,were used for establishing a short term experiment model:91 healthy male wistar laboratory rats were randomly devived into seven groups,eath of which contains 13 animals,being consecutively fed with animal food containing different objiects or filled stomach along with treatment by abdomen injection of one dose diethylnitrosamine 100mg/kg.bw,respectively.Then 0.015%2-AAF solution which was mixed into the normal food was administered to the rat for two weeks.Two-thirds partial hepatectomy was performed after seven days for taking 2-AAF.13 rats for A,B,C,D,E,F,G,the leaves residues group,the flowers of Camellia chrysantha(Hu)Tuyama group,2.5%,5%,7.5%,10%the concentrated liquids of CCT and the positive control group.Five pieces of liver were taken from each rat.The preneoplastic nodules forγ-GT positive foci in liver sections were measured,then the total areas of the positive foci per square centimeter(mm~2/cm~2),the average acreage per positive foci(mm~2/foci), and the amount of positive foci per square centimeter(foci/cm~2)were calculated repectively.The expression of proliferating cell nuclear antigen protein was determined with immunohistochemistry and compared withγ-GT positive foci.Results:1.The total areas of positive foci forγ-GT in group A,B,C,D were 9.85±4.17,5.72±3.83,8.81±3.70,6.33±2.97;the positive foci per square centimeter were 56.39±17.80,36.90±23.09,53.97±16.17,40.40±11.82;the average areas per positive foci were:0.16±0.07,0.15±0.05,0.13±0.03, 0.14±0.05.the lest of the total areas of positive foci and the positive foci per square centimeter was group B.2.The total areas of positive foci forγ-GT in group A,B,C,D,E,F,G were 5.23±2.99,1.59±1.16,1.94±1.34,1.85±1.19,2.59±2.53,1.65±1.18,6.39±2.76. respectively.The positive foci per square centimeter were 37.08±17.34, 16.24±8.80,17.74±9.80,14.57±8.11,26.19±22.00,12.89±9.08,45.58±13.01;The average areas per positive foci were:0.13±0.03,0.10±0.02,0.10±0.03,0.10±0.04, 0.10±0.05,0.11±0.03,0.12±0.04.The total acreage of positive foci and the amount of positive foci per square centimeter in groupB,C,D,E,F were all less than the group G(p＜0.05)There was no difference for the average areas per positive foci between different groups(p＞0.05).From group A,B,C,D,E,F and G,the organ coefficient of liver(g/100g)were 1.97±0.46,2.30±0.34, 2.45±0.24,2.64±0.15,2.50±0.30,2.46±0.25,1.94±0.19.The organ coefficient in groupB,C,D,E,and F were more than that in group A and G,(p＜0.05).PCNA and r-GT could have same effect on weighing precancerous lesion to liver of rat.Conclusion:1.The best dose of diethylnitrosamine and 2-acetylaminofluorene,which can induce liver cancer of rats was DEN 100mg/kg.bw and 2-AAF 0.015%.2.The different concentrated liquids of CCT and the flowers of CCT could inhibit the growth of the hepatic cells in the preneoplastic nodules,CCT can be used to protective liver.3.Inhibiting the growth of the hepatic cells in the preneoplastic nodules of the different concentrated liquids of CCT show dose-effect-realationship,the effecttive element of CCT was water-solubility substance.4.PCNA and r-GT have same effect on weighing precancerous lision to liver of rat.PCNA could be an new one of signs weighing liver cancer preneoplastic nodules.5.Camellia Chrysantha(Hu)Tuyama flowers and concentrated liquids can resist toxicity action of diethylnitrosamine and have protective effect to liver.
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