ABSTRACT
The present study aimed to investigate the hepatoprotective effects of methyl ferulic acid (MFA) against oxidative stress and apoptosis in acute liver injury induced by carbon tetrachloride (CCl4) in rats, as well as the underlying mechanisms. Sprague Dawley rats were treated with CCl4 after oral administration of MFA (25, 50, and 100 mg/kg) or dimethyl diphenyl bicarboxylate (200 mg/kg) for 7 days. The hepatoprotective effects of MFA were determined by analyzing serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities as well as changes of oxidant parameters. Histopathological analysis was performed to determine the degree of hepatic injury. The mechanisms were investigated by detecting the levels of NADPH oxidase (NOX) trans-membrane subunit NOX4, its ligand p22phox, as well as caspase3, cleaved caspase3, B-cell lymphoma (Bcl)-2, Bcl-2-associated X protein (Bax), tumor necrosis factor (TNF)-α, interleukin (IL)-1, reactive oxygen species (ROS), thiobarbituric acid-reactive substances (TBARS), total anti-oxidant capacity (TAC), phosphorylated J-Jun N-terminal kinase (p-JNK) and p-p38 mitogen-activated protein kinase (MAPK) using semi-quantitative polymerase chain reaction, western blot analysis and colorimetric assays. MFA treatment significantly decreased serum enzymatic activities of ALT and AST. MFA markedly increased activities of liver superoxide dismutase, catalase and glutathione peroxidase, and reduced the malondialdehyde concentration. Histopathological examination demonstrated that MFA reduced lipid degeneration, cytoplasmic vacuolization, necrosis and inflammatory cell infiltration in the liversof CCl4-treated rats. MFA treatment markedly inhibited the expression of inflammatory factors TNF-α and IL-1ß. Mechanistic study revealed that MFA decreased the TAC and the levels of ROS and TBARS. Furthermore, MFA treatment led to a reduction of the mRNA and protein expression of NOX4 and p22phox, as well as the protein levels of caspase3, cleaved caspase-3 and Bax, and an upregulation of p-JNK, p-p38 MAPK and Bcl-2 proteins in the liver. The present study demonstrated that MFA has hepatoprotective effects against CCl4-induced acute liver damage. MFA has anti-oxidant, anti-inflammatory and anti-apoptotic activities and was able to modulate the NOX4/p22phox/ROS-JNK/p38 MAPK signaling pathway.