Abstract: In order to observe the histopathological change and the expression of P21 and Bcl - 2 protein in Aflatoxin B1 (AFB1)2induced rat hepatic putative preneoplastic lesions alleviated by lithium carbonate (Li2CO3) . 144 healthy Wistar rat s(155g～175g) were divided randomly into four groups (A , normal cont rol group ; B , positive cont rol group ; C , group t reated with Li2CO3 simultaneously ; D , group pre2t reated with Li2CO3) and sacrificed in batches in the 6th , 9th or 10th week of the experiment . Histopathological assay and immunohistochemical assay of P21 and Bcl - 2 protein was made on hepatic. The result showed that the severity of prenoplasm alleviated in Group C and Group D , and that , coinciding with the histopathological discoveries , a tendency of“Group B >Group C > Group D > Group A”could be found in observation of P21 and Bcl - 2 protein expressive , which occurred in the early stage ( the 6th week) and significantly increased in the 9th , 10th week. It suggested that Li2CO3 has definite anticarcinogenic and preventive effect on hepatoma induced by chemicals and the continual analysis of P21 and Bcl - 2 protein may help early discovery and prognostic judgment of hepatoma.

Key words: P21, Bcl - 2, Li2CO3, Rat hepatic, Preneoplastic lesion