摘要：Peroxisome proliferators stimulate hepatocyte growth in rat liver in vivo . Activin A, a homodimer of inhibin βA, inhibits DNA synthesis in hepatocytes. The inhibitory action of activin A is suppressed by follistatin, an activin-binding protein. In this paper, we investigated whether administration of di- n -butyl phthalate (DBP), a peroxisome proliferator, modifies the production of activin A and follistatin in rat liver by hourly monitoring of inhibin βA and follistatin mRNA levels by reverse transcriptase polymerase chain reaction analysis. The mRNA levels of the other inhibin β chains (inhibin βB and βC) were examined in a similar manner. The inhibin βA mRNA level decreased to about 30% by 3 h after DBP administration (8.6 mmol/kg body weight), remained low until 12 h, and returned to its original level by 24 h. The follistatin mRNA level increased to about 2 times by 6 h, and returned to its original level by 24 h. The inhibin βB mRNA had started to increase by 1 h, peaked at 6 h at about 4 times its initial level, and returned to its original level by 12 h. The inhibin βC mRNA level had doubled by 6 h and it returned to its original level. These results indicate that the growth stimulatory action of peroxisome proliferators may be mediated via the decrease in activin A level and activity and suggest that the increases in follistatin as well as inhibin βB and βC chains may play a role in peroxisome proliferator-stimulated hepatocyte growth.
