The Antioxidant N-Acetylcysteine Prevents the Mitochondrial Fragmentation Induced by Soluble Amyloid-F Peptide Oligomers

Abstract

<i>Background:</i> Soluble amyloid-F peptide oligomers (AFOs), which are centrally involved in the pathogenesis of Alzheimer’s disease, trigger Ca<sup>2+</sup> influx through N-methyl-<i>D</i>-aspartate receptors and stimulate reactive oxygen species generation in primary hippocampal neurons. We have previously reported that AFOs promote Ca<sup>2+</sup> release mediated by ryanodine receptors (RyR), which in turn triggers mitochondrial fragmentation. We have also reported that the antioxidant N-acetylcysteine (NAC) prevents AFOs-induced Ca<sup>2+</sup> signal generation. <i>Objectives:</i> To determine if RyR-mediated Ca<sup>2+</sup> release activated by the specific agonist 4-chloro-m-cresol (4-CMC) induces fragmentation of the mitochondrial network, and to ascertain if NAC prevents the mitochondrial fragmentation induced by AFOs and/or 4-CMC. <i>Methods:</i> Mature primary rat hippocampal neurons were incubated for 24 h with sublethal concentrations of AFOs (500 n<i>M</i>) or for 1–3 h with 4-CMC (0.5–1 m<i>M</i>), w10 m<i>M</i> NAC. Mitochondrial morphology was assessed by confocal microscopy of fixed neurons stained with anti-mHsp70. Intracellular Ca<sup>2+</sup> levels were determined by time series microscopy of neurons preloaded with Fluo-4 AM. <i>Results:</i> Preincubation of neurons for 30 min with NAC prevented the mitochondrial fragmentation induced by AFOs or 4-CMC. In addition, we confirmed that preincubation with NAC abolished the stimulation of RyR-mediated Ca<sup>2+</sup> release induced by AFOs or 4-CMC. <i>Conclusion:</i> The present results strongly suggest that the general antioxidant NAC prevents AFO-induced mitochondrial fragmentation by preventing RyR-mediated Ca<sup>2+</sup>-induced Ca<sup>2+</sup> release. Copyright i 2012 S. Karger AG, Basel