Chronic restraint stress reduces carbon tetrachloride-induced liver fibrosis

Stress as a cofactor has been reported to affect the progression and severity of liver diseases. The present study investigated the effect of chronic restraint stress on carbon tetrachloride (CCl₄)-induced liver fibrosis. A total of 30 male BALB/c mice were randomly divided into three groups: Oil-treated control group; CCl₄-treated group; and CCl₄ + restraint-treated group. CCl₄ was administrated via intraperitoneal injection once every 3 days over a period of 42 days. In the CCl₄ + restraint-treated group, mice were immobilized using 50 ml centrifuge tubes for 0.5 h to inflict chronic restraint stress immediately after the injection of CCl₄. On day 42, blood and liver tissue samples were collected for analysis. The effect of restraint on CCl₄-induced liver fibrosis in mice was evaluated by analyzing the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Histopathological examination of liver samples was performed using hematoxylin and eosin (HE), Masson's trichrome, 5-hydroxytryptamine 2B (5-HT2B) receptor and α-smooth muscle actin (α-SMA) immumohistochemical staining. ALT, AST, 5-HT2B receptor and α-SMA expression levels were significantly increased in mice exposed to CCl₄ in comparison with those in the oil-treated control mice (P<0.01). However, these increases were significantly reduced by exposure to restraint (P<0.05). HE and Masson's trichrome staining revealed that restraint can alleviate CCl₄-induced liver fibrosis. These results suggest that chronic restraint stress reduces the development of liver fibrosis by inhibiting the activation of hepatic stellate cells via 5-HT2B receptor. Therefore, restraint may be a useful therapeutic approach in the management of liver fibrosis.