Adult Leech CNS Regeneration at the Single Cell Level: Effects of Electrical Stimulation

Central nervous systems (CNS) of adult mammals fail to regenerate following an injury. Invertebrates` CNS, on the other hand, can undergo substantial regeneration with significant functional recovery. Moreover, many invertebrates provide the opportunity to work with identified neurons based on their size, location and characteristic electrical activity pattern within the tissue. Thus, invertebrates serve as a useful model for exploring cell strategies and mechanisms underlying successful CNS regeneration at the single cell level. Electrical stimulation (ES) has been previously reported as a promoting factor of axonal regeneration in sensory and motor neurons. The effects have been demonstrated mostly in the PNS but there are also experimental evidence for such occurrence in the CNS. For example, low-frequency ES at 20 Hz for a short period was found to be as effective as continuous stimulation over 2 weeks. In this research we aim to study the influence of different ESs on the neuronal growth. We have examined the effects of brief ES (20Hz, 30min) on the regeneration strategy of the leech CNS at the single cell level over a period of 72 hours. We used an ex-vivo model of the leech ganglia chain. We followed the regeneration process of single cells and compared the regeneration strategy with and without the electrical stimulation.

Our preliminary results demonstrate that regenerated neurons under ES tend to change their dendritic tree orientation but not the total branching tree length, as compared to control neurons. The results suggest that ES may direct the spatial orientation of regenerating axons, contributing to targeted growth. We demonstrate that a brief ES may be a useful method for effective neuronal recovery post trauma.