Tropisetron Protects Against Acetaminophen-Induced Liver Injury via Suppressing Hepatic Oxidative Stress and Modulating the Activation of JNK/ERK MAPK Pathways

Abstract

Objectives. To investigate the protective effects of tropisetron on acetaminophen- (APAP-) induced liver injury in a mice model. Methods. C57BL/6 male mice were given tropisetron (0.3 to 10 mg/kg) 30 minutes before a hepatotoxic dose of acetaminophen (300 mg/kg) intraperitoneally. Twenty hours after APAP intoxication, sera alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, hepatic myeloperoxidase (MPO), malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) activities, and liver histopathological changes were examined. The MAP kinases were also detected by western blotting. Results. Our results showed that tropisetron pretreatment significantly attenuated the acute elevations of the liver enzyme ALT level, hepatic MPO activity, and hepatocytes necrosis in a dose-dependent manner (0.3-10 mg/kg) in APAP-induced hepatotoxicity mice. Tropisetron (1 and 3 mg/kg) suppressed APAP-induced hepatic lipid peroxidation expression and alleviated GSH and SOD depletion. Administration of tropisetron also attenuated the phosphorylation of c-Jun-NH2-terminal protein kinase (JNK) and extracellular signal-regulated kinase (ERK) caused by APAP. Conclusion. Our data demonstrated that tropisetron's hepatoprotective effect was in part correlated with the antioxidant, which were mediated via JNK and ERK pathways on acetaminophen-induced liver injury in mice.

Figure 1

Protection effect of tropisetron in APAP-induced liver injury. Mice were intraperitoneally administered with APAP 300 mg/kg alone or with various concentrations of tropisetron (TP: 0.3 to 10 mg/kg) at 30 min before APAP injection and were sacrificed 20 h after administration for assay of sera ALT (a) and AST (b). Results are mean ± SEM; n = 6 mice per group. ^# P < 0.005 versus control (normal saline); ^∗∗ P < 0.01; ^∗∗∗ P < 0.005 versus APAP alone.

Figure 2

Tropisetron protects against APAP-induced hepatic MPO increase. Injured mice were given APAP 300 mg/kg alone or with various concentrations of tropisetron (TP: 0.3 to 10 mg/kg) at 30 min before APAP injection and were sacrificed 20 h after administration for assay of liver MPO. Results are mean ± SEM; n = 6 mice per group. ^# P < 0.005 versus control (normal saline); ^∗ P < 0.05; ^∗∗∗ P < 0.005 versus APAP alone.

Figure 3

Tropisetron protects against APAP-induced hepatic GSH, SOD depletion, and MDA increase. Mice were administered with APAP 300 mg/kg alone or with tropisetron (TP: 1 and 3 mg/kg) at 30 min before APAP injection and were sacrificed 20 h after administration for assay of liver GSH (a), SOD (b), and MDA (c). Results are mean ± SEM; n = 6 mice per group. ^# P < 0.005 versus control (normal saline); ^∗ P < 0.05; ^∗∗ P < 0.01; ^∗∗∗ P < 0.005 versus APAP alone.

Figure 4

Tropisetron reduces APAP-induced liver injury in histology. Mice were given (a) control (normal saline) and (b) APAP 300 mg/kg alone or with various concentrations of tropisetron ((c) 1 mg/kg; (d) 3 mg/kg; (e) 10 mg/kg) at 30 min before APAP injection and were sacrificed 20 h after administration for assay by H&E stain (magnification: left column ×50, right column ×100).

Figure 5

Tropisetron attenuates hepatic JNK and ERK expression in APAP-induced hepatic injury. (a) Hepatic p-JNK and JNK protein expression from shams receiving vehicle (sham + C: control; lane 1) or tropisetron (sham + TP3: 3 mg/kg; lane 2), treatment with acetaminophen (APAP: 300 mg/kg) receiving vehicle (APAP + control; lane 3), tropisetron (APAP + TP3: 3 mg/kg; lane 4), tropisetron (APAP + TP1: 1 mg/kg; lane 5), JNK inhibitor SP600125 (APAP + SP: 30 mg/kg; lane 6), or SP600125 plus tropisetron (APAP + SP + TP3; lane 7). (b) Hepatic p-ERK and ERK protein expression from shams receiving vehicle (sham + C: control; lane 1) or tropisetron (sham + TP3: 3 mg/kg; lane 2), treatment with acetaminophen (APAP: 300 mg/kg) receiving vehicle (APAP + control; lane 3), tropisetron (APAP + TP3: 3 mg/kg; lane 4), tropisetron (APAP + TP1: 1 mg/kg; lane 5), ERK1/2 inhibitor PD98059 (APAP + PD: 10 mg/kg; lane 6), or PD98059 plus tropisetron (APAP + PD + TP3; lane 7).

Figure 6

Survival analysis of APAP-induced liver injury in mice. Mice were intraperitoneally treated with 0.9% normal saline, with APAP 300 mg/kg alone, or with a 3 mg/kg concentration of tropisetron at 30 min before APAP injection. (a) The survival rate was measured until 96 h after normal saline or APAP 300 mg/kg administration (n = 8/each group). (b) All animals were sacrificed at 96 h after administration for assay of serum ALT.