Neurite Outgrowth and Retraction Caused by Optical Stimulations
Yu-Chiu Kao1*, Yu-Cing Liao1,2, Chau-Hwang Lee1,2
1Research Center Applied Sciences, Academia Sinica, Taipei, Taiwan
2Institute of Biophotonics, National Yang-Ming Univeraity, Taipei, Taiwan
* Presenter:Yu-Chiu Kao,
The regeneration and repair of damaged neuronal networks are difficult to study in vivo. Understanding the processes involved in neuronal repair is essential for advancing our knowledge to treat neuron injuries and neurodegenerative diseases. Laser light of various wavelengths has been used to stimulate neurite outgrowth, but the detailed mechanisms are still under investigation.
In this study, we used focal spots of 473 nm blue light and 650 nm red light to respectively illuminate the neurites and soma of mouse neuroblastoma cell N2a. We found that the blue light could cause neurite retraction, while the red light spot on the soma is beneficial for neurite outgrowth from the illumination site. Because the blue-light-induced neurite retraction was partially impeded by blebbistatin, an inhibitor of myosin II, we conjectured that the neurite retraction was driven by the actin–myosin cytoskeletal force. Furthermore, we also showed that blebbistatin accelerated the red-light-induced neurite outgrowth. Although it was speculated that a focused light spot might cause the aggregation of actin and facilitate neurite outgrowth, our data obtained with other wavelengths of laser light did not agree with this hypothesis. We thus suspect that the illumination of red light could specifically induce some intracellular responses that help neurite growth in neuroblastoma cell.

Keywords: optical stimulation, neurite outgrowth and retraction, myosin cytoskeletal force