Melatonin inhibits free radical-mediated mitochondrial-dependent hepatocyte apoptosis and liver damage induced during malarial infection.
We showed earlier that malarial infection significantly induces liver apoptosis mediated by oxidative stress mechanisms. Thus, a nontoxic antioxidant-antiapoptotic molecule may be beneficial for hepatoprotection. Melatonin remarkably prevents hepatocyte apoptosis in mice induced during malaria as indicated by caspase 3 and TUNEL assays as well as transmission electron microscopy (TEM) of the liver tissue. The mitochondrial apoptotic pathway, which plays a critical role in liver cell death during malarial infection, was almost completely suppressed by melatonin as it corrects both the overexpression of Bax and down-regulation of bcl-2 as revealed by semiquantitative RT-PCR. Fluorometric studies using JC-1 documented that melatonin also restores mitochondrial transmembrane potential (DeltaPsim) in malaria-infected mice liver. The antiapoptotic effect of melatonin is associated with its antioxidant role because melatonin protects liver from oxidative stress induced during malaria by scavenging the hydroxyl radicals, preventing the depletion of reduced glutathione, inhibiting lipid peroxidation and protein carbonyl formation. The effective antioxidant dose of melatonin to protect liver from oxidative stress during malaria is 20 times lower than that of known antioxidants, vitamin C and vitamin E. Apoptosis of hepatocytes during malarial infection is well correlated with dysfunction of the liver while melatonin offers hepatoprotective effects as indicated by different liver function tests. Thus, melatonin may well be effective in combating oxidative stress-induced apoptosis and liver damage during malaria infection.
Guha
Mithu
M
Division of Infectious Diseases and Immunology, Indian Institute of Chemical Biology, Kolkata, West Bengal, India.
Maity
Pallab
P
Choubey
Vinay
V
Mitra
Kalyan
K
Reiter
Russel J
RJ
Bandyopadhyay
Uday
U
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005609:Free Radicals / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D022781:Hepatocytes / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D017665:Hydroxyl Radical / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008099:Liver / Q000187:drug effects* / Q000469:parasitology / Q000473:pathology; D008111:Liver Function Tests; D008288:Malaria / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D008550:Melatonin / Q000494:pharmacology*; D051379:Mice; D008854:Microscopy, Electron; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010967:Plasmodium yoelii / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051028:bcl-2-Associated X Protein / Q000235:genetics
D000975:Antioxidants; D005609:Free Radicals; D017382:Reactive Oxygen Species; D051028:bcl-2-Associated X Protein; D017665:Hydroxyl Radical; D053148:Caspase 3; D008550:Melatonin