engleski

Beneficial effect of polyphenol quercetin against oxidative injury in the culture of P19 neurons is mediated by the prevention of caspase-independent apoptosis

Introduction: Neuronal loss is a key observation of neurodegeneration implicated in the dysfunctions of the mammalian brain in physiological aging and numerous diseases and injuries. It is hypothesized that a dietary polyphenol supplementation could be an effective therapeutic strategy in minimizing the undesirable neuronal death. Materials and methods: Effects of ubiquitous flavonoid quercetin on neuronal death induced by exposure to 150 microM hydrogen peroxide (H2O2) for 24 hours were studied in the culture of P19 neurons. Reverse transcriptase PCR and western blot analysis were used to monitor changes in Bcl-2, Bax and PARP expression following H2O2 treatment. Changes in nuclear condensation were observed by Hoechst staining, while activities of key apoptotic markers caspase-3 and -7, and lactate dehydrogenase (LDH) activity were performed using commercially available assays (Promega). Results: Exposure to H2O2 decreased neuronal viability without changes in plasma membrane integrity, induced changes in chromatin condensation, slightly decreased Bcl-2 expression and moderately increased caspase-3/7 activity. Moreover, H2O2 induced strong PARP overexpression without PARP cleavage, altogether indicating a programmed type of cell death distinct from classical apoptosis. Presence of quercetin attenuated the toxic effects of H2O2 by preventing chromatin condensation and H2O2-induced changes in caspase activity, as well as changes in Bcl-2 and PARP expression. Conclusion: The obtained results suggest that the neuroprotective effect of polyphenol quercetin is related to its ability to prevent caspase-independent, PARP-dependent programmed cell death cascade. Hence, beneficial effects of quercetin might be assumed for the prevention of oxidative-stress driven neuronal loss in human aging and neurodegenerative diseases.

quercetin; hydrogen peroxide; P19 neurons; caspase-independent apoptosis; PARP expression

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