Neurite Outgrowth Caused by Optical and Electrical Stimulations

Yu Chiu Kao^1*, Kuan Yun Lin^1,2, Chau Hwang Lee^1,2

¹Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
²Institute of Biophotonics, National Yang Ming Chiao Tung University, Taipei, Taiwan

* Presenter:Yu Chiu Kao, email:winipinky@gmail.com

Neurite growth is essential for constructing the nervous system in the development process and the repair after trauma or disease. Therefore, the mechanism for neurite growth is an important research topic in current neuroscience. Both optical and electrical stimulations-induced neurite outgrowth are proposed as potential of neuron repair techniques. In the present work, we used the co-stimulation of red light and direct-current electric fields (dcEFs) on the neurite growth of mouse neuroblastoma cells (N2a) and compared the results with those obtained by single stimulations.
We had previously confirmed that using a 650 nm laser spot to illuminate the soma of an N2a cell could cause neurite growth [1]. Herein, we added dcEFs into the neurite growth experiment. We found that 1-hour, 150 mV/mm dcEF stimulation can induce obvious neurite growth. We then combined optical and electric field stimulations to see if the ratio of neurite growth or the neurite grow length could be further increased. The statistics of experimental results showed that, the ratio of neurite growth under the optical and electrical co-stimulation was similar to that under the optical stimulation. On the other hand, the neurite growth lengths under the optical and electrical co-stimulation was close to those obtained by the dcEF stimulation. It seems that the co-stimulation could provide both the high ratio of neurite growth and the longest neurite growth lengths.
Calcium ion is one of the key regulators for neurite growth [2]. Using calcium indicator rhod-2AM, we observed that the concentration of calcium ions under the optical and dcEF stimulations reaches the highest point in 1 hour and 5 minutes, respectively. Obviously the red light and dcEF caused neurite growth with different molecular mechanisms. That may be the reason that no synergistic effect was observed on the growth of neurite. We are currently investigating other mediator of neurite growth related to optical and dcEF stimulations.

Keywords: Neurite growth, Optical stimulations, Electrical stimulations, Calcium ion