Involvement of IL-6 and IL-6 receptor in fibrinogen synthesis in the liver of Triton WR-1339-induced hyperlipidemic rats.

To clarify the mechanisms by which Triton WR-1339 causes an elevation in the plasma fibrinogen level, we studied the time courses of hepatic mRNA expression for beta-chain fibrinogen, interleukin-6 (IL-6) and IL-6 receptor (R) by RT-PCR. After intravenous injection of Triton WR-1339 (150, 300 and 500 mg/kg) in Sprague-Dawley rats, the plasma level of fibrinogen and MCP-1 significantly and dose-relatedly increased from 12 to 24 hours (h). At 3 and 6 hours dose dependent increases were found in hepatic IL-6 and IL-6R mRNA expression with increases in the hepatic mRNA expression for beta-chain fibrinogen as the rate-limiting step in fibrinogen synthesis. These results suggest that the increase in the plasma fibrinogen level is followed by the enhancement of hepatic mRNA expression of beta-chain fibrinogen, IL-6 and IL-6R, that is, IL-6 and IL-6R may partly regulate the plasma fibrinogen level in Triton WR-1339-induced hyperlipidemic rats.