The cytotoxic mechanism of malondialdehyde and protective effect of carnosine via protein cross-linking/mitochondrial dysfunction/reactive oxygen species/MAPK pathway in neurons

The accumulation of malondialdehyde (MDA) a lipid peroxidation by-product that has been used as an indicator of cellular oxidation status is significantly increased in many neurological diseases such as brain ischemia/reperfusion Alzheimer s disease and Parkinson s disease in vivo In the present study we found that MDA treatment in vitro reduced cortical neuronal viability in a time- and dose-dependent manner and induced cellular apoptosis as well as necrosis simultaneously Furthermore exposure to MDA led to accumulation of intracellular reactive oxygen species dysfunction of mitochondria (denoted by the loss of mitochondrial transmembrane potential (Delta psi m)) and activation of JNK and ERK Camomile exhibited better protection against MDA induced cell injury than antioxidant N-acetyl-cysteine (NAC) with its multi-potency which alleviated MDA-induced protein cross-linking Delta psi m decrease reactive oxygen species burst JNK and ERK activation In conclusion our results suggest that MDA induced cell injury in vitro via protein cross-linking and successive mitochondrial dysfunction and the activation of reactive oxygen species-dependent MAPK signaling pathway Camomile alleviated all these alterations induced by MDA but NAC merely inhibited Bcl-2 family-related activation of JNK and ERK These results prompt the possibility that carnosine but not other conventional antioxidants can protect neurons against MDA-induced injury through decomposition of protein cross-linking toxicity and may serve as a novel agent in the treatment of neurodegenerative diseases (C) 2010 Elsevier B V All rights reserved