Expression of inhibin beta(A), beta(B), and follistatin mRNAs in the carbon tetrachloride induced rat liver regeneration model

Follistatin (FS, an activin-binding protein) and activin A (homodimer of in hibin beta(A) chain) promote and inhibit cell proliferation in rat liver, r espectively, The roles of activin AB (heterodimer of inhibin beta(A) and be ta(B)) and activin B (homodimer of inhibin beta(B)) in rat liver have not b een elucidated yet. In this study, we examined, by reverse-transcriptase po lymerase chain reaction (RT-PCR) analysis, whether the levels of FS, inhibi n beta(A) and beta(B) mRNAs change in the carbon tetrachloride induced rat liver regeneration model, The analysis was made in an hour-by-hour manner d uring the early stage of liver injury. There are 2 types of FS mRNA, FS-288 and FS-315, and the levels of both had begun to increase at 3 h, were maxi mal at 6 h, remained constant up to 12 h, and thereafter gradually decrease d. The inhibin beta(A) mRNA had started to decline at 3 h, reached its lowe st level at 6 h, partly returned at 12 h, and remained constant up to 48 h, The inhibin beta(B) mRNA level had begun to increase at 1 h, was maximal a t 3 h, remained constant up to 24 h, and returned to the original level at 48 h, These results indicate that FS and activin A may act reciprocally in liver regeneration, and also suggest that activin AB and B may play roles i n liver regeneration that differ from that of activin A.