Stimulation Frequency Alters the Dorsal Root Ganglion Neurite Growth and Directionality In Vitro

To improve peripheral nerve repair, new techniques to increase the speed of regeneration are required. Studies have shown that the electrical stimulation can enhance nerve regeneration; however, stimulation parameters that regulate the growth increases are unknown. The objective of this study was to examine dorsal root ganglion (DRG) neurite extension, directionality, and density after using methods to specifically control ac electrical field intensity and frequency exposure.

Chick DRG explants were exposed to 20-Hz, 200-Hz, 1-MHz, and 20-MHz sinusoidal electric field of 17.86 V/m, and tissue parameters were measured.

Results show that neurite extension and directionality were influenced by frequency; however, the ratio of support cell emigration with respect to neurite extension from the DRG body was not. These results were further verified through finite-element modeling of intracellular calcium, which show that higher frequencies have minimal effect on intracellular calcium.

In conclusion, these results demonstrate that 1) directional growth of neurites within EFs can be achieved, 2) high-frequency stimulation in megahertz does not enhance or impair the neurite growth, and 3) low-frequency stimulation affects the growth and directionality.

The significance of this study is the direct comparison of neurite extension after high stimulation frequencies (megahertz) with typical low-frequency fields (20 and 200 Hz), and modeling the results with finite-element modeling.