Free radical research
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Free radical research · Dec 1999
Comparative StudyHemoglobin and iron-evoked oxidative stress in the brain: protection by bile pigments, manganese and S-nitrosoglutathione.
In the present in vitro and in vivo study we investigated the pro-oxidant effects of hemoglobin, as well as the antioxidant effects of its metabolites, in the brain. Incubation of rat brain homogenates with hemoglobin (0-10 microM) but not hemin induced lipid peroxidation up to 24 h (EC50 = 1.2 microM). Hemoglobin's effects were similar to ferrous ion (EC50 = 1.7 microM) and were blocked by the chelating agent deferoxamine (IC50 0.5 microM) and a nitric oxide-releasing compound S-nitrosoglutathione (IC50 = 40 microM). ⋯ In conclusion, contrary to the in vitro results hemoglobin is far less neurotoxic than ferrous ions in the brain. It is speculated that hemoglobin may be partially detoxified by heme oxygenase and biliverdin reductase to its antioxidative metabolites in the brain. However, in head trauma and stroke, massive bleeding could significantly produce iron-mediated oxidative stress and neurodegeneration which could be minimized by endogenous antioxidants such as biliverdin, bilirubin, manganese and S-nitrosoglutathione.