Investigation of Axonal Beading Induced by Photo-oxidation

Oxidative stress caused by the presence of excessive free radicals (reactive oxygen species) is known for its adverse effects in cellular function. When initiated by fluorescent dye excitation, it can lead to photo-oxidative stress, causing cellular damage. In this study, we investigate axonal beading induced by the photo-oxidation of a membrane based fluorescent dye. Our findings show that apart from the use of oxygen scavengers, chelation of free calcium and stabilizing microtubules or actin filaments by pharmacological agents can mitigate oxidative stress induced axonal beading. Furthermore, we take advantage of this light induced oxidative stress phenomenon to probe axonal response to spatially confined perturbations of varying strength. We demonstrate that low excitation levels lead to long-lived localized beading, whereas higher levels of excitation result in global degeneration and beading of axons. Besides the results presented here, this light based technique is a convenient tool to investigate the effect of local oxidative stress at the tissue level, for example, in cultures of brain slices or organoids.