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

Abstract

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.

Corticosteroids: do they damage the cardiovascular system?

“…Some of these actions might be seen as harmful to heart and circulation (Table II) and will be reviewed in more detail. 99 Fibrinogen production has been shown to increase in response to glucocorticoids both in vitro'00-102 and in vivo. 103,104 The natural defence to fibrin deposition and clot formation is the fibrinolytic system, initiated by tissue plasminogen activator.…”

Ketoconazole blocks bile acid synthesis in hepatocyte monolayer cultures and in vivo in rat by inhibiting cholesterol 7 alpha-hydroxylase.

“…Rat liver cells were isolated by perfusion with 0.05% collagenase and 0.005% trypsin inhibitor as described previously (21). Viability, as determined by trypan blue exclusion, was higher than 90%.…”

Study on the molecular mechanism of the decreased liver synthesis of albumin in inflammation

“…However, the precise molecular mechanism for the reduction of albumin synthesis has still not been completely elucidated. Nevertheless, a number offactors have been suggested to play an important role in the regulation of liver synthesis of acute phase proteins, such as hormones, fibrinogen-, or fibrin degradation products, and monocytic products, including IL-1 (15,25,26). From our previous studies (7,25,26) and other investigations (data not shown) we have demonstrated that corticosteroids, growth hormone, insulin, adrenaline, fibrinogen, and fibrin degradation products cannot be implicated in modulating the hepatic synthesis of albumin during the acute-phase response, because administration of these hormones in vivo in rats or in vitro in experiments using primary cultures of rat hepatocytes did not lead to a reduced synthesis of albumin, although in other studies, the fibrinogen synthesis in rats could be stimulated by in vivo administration of fibrinogen or fibrin degradation products (26).…”

“…After redissolving the albumin precipitate in 10 ml of water and adjusting to pH 7.0 with I M NaOH, the entire procedure was repeated. The albumin fraction, 25 ml, was dialyzed overnight. The purity of the albumin preparation, determined by electrophoresis on cellulose acetate, (6) with some modifications as described previously (7).…”

“…Determination of 3H-labeled albumin in the culture medium was essentially performed as described previously (8). 25-,gl samples were diluted in 500 JI buffer containing 10 mM sodium phosphate, pH 7.2, 150 mM NaCl, 1% Triton X-100, 0.5% sodium deoxycholate, 0.1% sodium dodecyl sulfate (SDS), 5 mM leucine, 0.1 mM phenylmethylsulfonylfluoride, and 1 mM EDTA and incubated with 1,000 dpm ['4C]albumin as tracer for recovery, 20 Atg albumin as carrier, and goat-anti-rat albumin y-globulin. After 16 h incubation at 4°C, the mixture was layered over a 200-,ul 10% (wt/wt) sucrose cushion and centrifuged for 5 min in an Eppendorf centrifuge.…”