| This investigation examined the responses of mammalian cortical neurons to direct current electrical stimulation in vitro. An incubatable stimulator and setup was developed which can be utilized to study all types of mammalian cells or utilized on the benchtop with cells not in need of incubation. Cortical neurons showed a strong orientational response to the electric field by extending neurites towards the anode. 78.8% of the neurites of stimulated cells displayed this behavior compared to 33.3% of controls. The difference was significant. The orientation responses were field-strength dependent. Neurite length was also influenced by the stimulation. Field-treated neurites were significantly longer at 51.01mum, compared to those of non-treated cells at 40.3mum. Also included in this study was an investigation into the roles of the acetylcholine (Ach) and cyclic adenosine monophosphate (cAMP) pathways in the cortical neuron response. The Ach receptor pathway appears to play a role in the electric field's influence. A reduction in the neurite anodal orientation occurred when the nicotinic Ach pathway was blocked. Also, the field-induced increased length observed was abolished when the cAMP pathway was inhibited. It is possible that this pathway is also involved. These findings suggest that the galvanotropism of cortical neurites acts in part through the Ach pathway. This study has shown that under direct current (DC) stimulation, cortical neurites (1) orient towards the anode, (2) have increased length, (3) have more initiation sites on the anode side, (4) respond in a field-strength dependent manner, (5) are influenced in part through the nicotinic Ach pathway, and (6) show enhanced survival when stimulation is combined with nerve growth factor. These findings suggest that DC stimulation may have beneficial effects as a therapeutic treatment on cortical neurons. |
