Immobilization stress induces c-Fos accumulation in liver

Acute stress-induced injury in tissues has been revealed by both biochemica l markers in plasma and microscopy. However, little is known of the mechani sms by which tissue integrity is restored. Recently, induction of early res ponse genes such as c-fos has been reported in the heart and stomach of imm obilized animals. Herein, we show that immobilization stress in mice increa sed plasma alanine aminotransferase activity, a marker of liver damage, c-F os protein accumulation in liver was induced by stress after 20 minutes of immobilization and persisted for 3 hours. Immobilization also induced the r elease of epidermal growth factor (EGF) from submandibular salivary glands and a transient increase in EGF concentration in plasma. Although EGF admin istration induced a 2.5-fold increase in c-Fos mass in the liver of anesthe tized mice, sialoadenectomy (which abolished the effect of immobilization o n plasma EGF) did not affect the stress-induced rise in plasma alanine amin otransferase activity or liver c-Fos accumulation. Therefore, we conclude t hat immobilization stress induces c-Fos accumulation in liver and that this effect is not triggered by the increase in plasma EGF concentration.