ERK Signaling Pathway Plays a Key Role in Baicalin Protection Against Acetaminophen-Induced Liver Injury.

Acetaminophen (APAP) overdose causes hepatocytes necrosis and acute liver failure. Baicalin (BA), a major flavonoid of Scutellariae radix, has potent hepatoprotective properties in traditional medicine. In the present study, we investigated the protective effects of BA on a APAP-induced liver injury in a mouse model. The mice received an intraperitoneal hepatotoxic dose of APAP (300mg/kg) and after 30 min, were treated with BA at concentrations of 0, 15, 30, or 60 mg/kg. After 16 h of treatment, the mice were sacrificed for further analysis. APAP administration significantly elevated the serum alanine transferase (ALT) enzyme levels and hepatic myeloperoxidase (MPO) activity when compared with control animals. Baicalin treatment significantly attenuated the elevation of liver ALT levels, as well as hepatic MPO activity in a dose- dependent manner (15-60 mg/kg) in APAP-treated mice. The strongest beneficial effects of BA were seen at a dose of 30 mg/kg. BA treatment at 30mg/kg after APAP overdose reduced elevated hepatic cytokine (TNF-alpha and IL-6) levels, and macrophage recruitment around the area of hepatotoxicity in immunohistochemical staining. Significantly, BA treatment can also decrease hepatic phosphorylated extracellular signal-regulated kinase (ERK) expression, which is induced by APAP overdose. Our data suggests that baicalin treatment can effectively attenuate APAP-induced liver injury by down-regulating the ERK signaling pathway and its downstream effectors of inflammatory responses. These results support that baicalin is a potential hepatoprotective agent.