Melatonin attenuates lipopolysaccharide (LPS)-induced apoptotic liver damage in D-galactosamine-sensitized mice.
D-Galactosamine (GalN) depletes UTP primarily in liver, resulting in decreased RNA synthesis in hepatocytes. When given together with a sublethal dose of lipopolysaccharide (LPS), GalN highly sensitizes animals to produce apoptotic liver injury with severe hepatic congestion, resulting in rapid death. Melatonin is a cytokine modulator, antioxidant and anti-apoptotic agent. In the present study, we investigated the effect of melatonin on LPS-induced apoptotic liver damage in GalN-sensitized mice. Female CD-1 mice were intraperitoneally (i.p.) injected with melatonin (5.0mg/kg) 30min before GalN/LPS (700mg10microg/kg, i.p.), another two doses of melatonin (2.5mg/kg, i.p.) being administered 1 and 2h after GalN/LPS. Results showed that serum alanine aminotransferase (ALT) activities were markedly increased 8h after GalN/LPS treatment, massive hemorrhage being observed in histological sections of liver from GalN/LPS-treated mice. Melatonin significantly attenuated GalN/LPS-induced elevation of serum ALT. In parallel, melatonin distinctly improved GalN/LPS-induced congestion. Additional experiment showed that melatonin significantly attenuated GalN/LPS-induced hepatic apoptosis, measured by inhibition of caspase-3 activities and attenuation of DNA laddering. Furthermore, melatonin markedly increased hepatic Se-dependent glutathione peroxidase (GSH-Px) and glutathione reductase (GSH-Rd) activities and attenuated hepatic glutathione (GSH) depletion in GalN/LPS-treated mice. Increases in serum tumor necrosis factor alpha (TNF-alpha), which were observed in GalN/LPS-treated mice, were significantly reduced by melatonin. However, melatonin had no effect on LPS-evoked nitric oxide production in GalN-sensitized mice. Taken together, these results indicate that melatonin protected against LPS-induced liver damage in GalN-sensitized mice through its strong ROS-scavenging, antiinflammatory and antiapoptotic effects.
Wang
Hua
H
Department of Toxicology, Anhui Medical University, Hefei 230032, PR China.
Xu
De-Xiang
DX
Department of Toxicology, Anhui Medical University, Hefei 230032, PR China; Institute of Clinical Pharmacology, Anhui Medical University, Hefei 230032, PR China. Electronic address: xudex@mail.hf.ah.cn.
Lv
Jin-Wei
JW
Department of Toxicology, Anhui Medical University, Hefei 230032, PR China.
Ning
Huan
H
Department of Toxicology, Anhui Medical University, Hefei 230032, PR China.
Wei
Wei
W
Institute of Clinical Pharmacology, Anhui Medical University, Hefei 230032, PR China. Electronic address: wwei@ahmu.edu.cn.
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D056486:Chemical and Drug Induced Liver Injury / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D053938:DNA Fragmentation; D004357:Drug Synergism; D005260:Female; D005688:Galactosamine / Q000633:toxicity*; D005978:Glutathione / Q000378:metabolism; D008070:Lipopolysaccharides / Q000633:toxicity*; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D008550:Melatonin / Q000008:administration & dosage / Q000627:therapeutic use*; D051379:Mice; D008815:Mice, Inbred Strains; D009569:Nitric Oxide / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D000975:Antioxidants; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D005688:Galactosamine; D000410:Alanine Transaminase; D053148:Caspase 3; D005978:Glutathione; D008550:Melatonin