The influence of glucocorticoid on the fibrinogen messenger RNA content of rat liver in vivo and in hepatocyte suspension culture.

The plasma concentration of fibrinogen, one of the major acute-phase proteins produced by the liver, increases during the acute-phase response as a result of enhanced synthesis in liver. Since adrenal-cortical hormones have been thought to have a key role in the regulation of the fibrinogen synthesis, fibrinogen-polypeptide mRNA sequences were determined in the present study, by using a specific complementary-DNA probe, in RNA fractions obtained from rat hepatocytes exposed to glucocorticoids in vitro (hepatocyte suspension cultures) and in vivo. Maximal induction of the fibrinogen-polypeptide mRNA (to 400% of the control value) was found in vitro at 0.1 microM-dexamethasone after 9 h of incubation. The same magnitude of induction was obtained with 20 microM-cortisol or 60 microM-corticosterone. In contrast with the findings in vitro, no induction of the fibrinogen-polypeptide mRNA was observed in the liver at various times after injection of different doses of glucocorticoids into rats. These results suggest that more complex regulatory mechanisms are involved and that glucocorticoids are not the sole regulatory factors in vivo in the enhanced synthesis of fibrinogen during the acute-phase response.