beta-Amyloid toxicity in organotypic hippocampal cultures: protection by EUK-8, a synthetic catalytic free radical scavenger.
Oxygen free radicals have been proposed to mediate amyloid peptide (beta-AP)-induced neurotoxicity. To test this hypothesis, we evaluated the effects of EUK-8, a synthetic catalytic superoxide and hydrogen peroxide scavenger, on neuronal injury produced by beta-AP in organotypic hippocampal slice cultures. Cultures of equivalent postnatal day 35 (defined as mature) and 14 (defined as immature) were exposed to various concentrations of beta-AP (1-42 or 1-40) in the absence or presence of 25 microM EUK-8 for up to 72 hours. Neuronal injury was assessed by lactate dehydrogenase release and semiquantitative analysis of propidium iodide uptake at various times after the initiation of beta-AP exposure. Free radical production was inferred from the relative increase in dichlorofluorescein fluorescence, and the degree of lipid peroxidation was determined by assaying thiobarbituric acid-reactive substances. Treatment of mature cultures with beta-AP (50-250 microg/ml) in serum-free conditions resulted in a reproducible pattern of damage, causing a time-dependent increase in neuronal injury accompanied with formation of reactive oxygen species. However, immature cultures were entirely resistant to beta-AP-induced neurotoxicity and also demonstrated no dichlorofluorescein fluorescence or increased lipid peroxidation after beta-AP treatment. Moreover, mature slices exposed to beta-AP in the presence of 25 microM EUK-8 were significantly protected from beta-AP-induced neurotoxicity. EUK-8 also completely blocked beta-AP-induced free radical accumulation and lipid peroxidation. These results not only support a role for oxygen free radicals in beta-AP toxicity but also highlight the therapeutic potential of synthetic radical scavengers in Alzheimer disease.
Bruce
A J
AJ
Neuroscience Program, University of Southern California, Los Angeles 90089-2520, USA.
Malfroy
B
B
Baudry
M
M
D016564:Amyloid beta-Protein Precursor / Q000633:toxicity*; D000818:Animals; D001692:Biological Transport; D002463:Cell Membrane Permeability / Q000187:drug effects; D046508:Culture Techniques; D005029:Ethylenediamines / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry*; D006624:Hippocampus / Q000187:drug effects*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D011419:Propidium / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000633:toxicity
D016564:Amyloid beta-Protein Precursor; D005029:Ethylenediamines; D016166:Free Radical Scavengers; D009942:Organometallic Compounds; D017382:Reactive Oxygen Species; D011419:Propidium; C090577:N,N'-bis(salicylideneamino)ethane-manganese(II); D007770:L-Lactate Dehydrogenase