Riquelme D, Alvarez A, Leal N, Adasme T, Espinoza I, Valdés JA, Troncoso N, Härtel S, Hidalgo J, Hidalgo C, & MA Carrasco
Antioxid Redox Signal. 14(7):1245-59
Abstract Neuronal electrical activity increases intracellular Ca(2+) concentration and generates reactive oxygen species. Here, we show that high frequency field stimulation of primary hippocampal neurons generated Ca(2+) signals with an early and a late component, and promoted hydrogen peroxide generation via a neuronal NADPH oxidase. Hydrogen peroxide generation required both Ca(2+) entry through N-methyl-D-aspartate receptors and Ca(2+) release mediated by ryanodine receptors (RyR). Field stimulation also enhanced nuclear translocation of the NF-κB p65 protein and NF-κB -dependent transcription, and increased c-fos mRNA and type-2 RyR protein content. Preincubation with inhibitory ryanodine or with the antioxidant N-acetyl L-cysteine abolished the increase in hydrogen peroxide generation and the late Ca(2+) signal component induced by electrical stimulation. Primary cortical cells behaved similarly as primary hippocampal cells. Exogenous hydrogen peroxide also activated NF-κB-dependent transcription in hippocampal neurons; inhibitory ryanodine prevented this effect. Selective inhibition of the NADPH oxidase or N-acetyl L-cysteine also prevented the enhanced translocation of p65 in hippocampal cells, while N-acetyl L-cysteine abolished the increase in RyR2 protein content induced by high frequency stimulation. In conclusion, the present results show that electrical stimulation induced reciprocal activation of ryanodine receptor-mediated Ca(2+) signals and hydrogen peroxide generation, which stimulated jointly NF-κB activity.
Acknowledgments This work was supported by Fondo Nacional de Investigación Científica y Tecnológica (FONDECYT) grant 1060177 (MAC), by FONDAP Center for Molecular Studies of the Cell grant 15010006 (CH), and by Enlace FONDECYT-VID ENL 09/02 (MAC). SCIAN-Lab is a member of the German-Chilean Center of Excellence Initiative for Medical Informatics (DAAD) and the Advanced Imaging & Bioinformatics Initiative AI·BI (www.aibi.cl. Research in SCIAN-Lab (SH) is funded by FONDECYT 1090246, FONDEF (D07I1019), and ICM-P04-068-F (NEMO).