Abstract
Background Electrical stimulation immediately following nerve lesion helps regenerating axons
cross the subsequently grafted nerve repair site. However, the results and the mechanisms
remain open to debate. Some findings show that stimulation after crush injury increases
axonal crossing of the repair site without affecting regeneration speed. Others show
that stimulation after transection and fibrin glue repair doubles regeneration distance.
Methods Using a sciatic-nerve-transection-graft in vivo model, we investigated the morphological
behavior of regenerating axons around the repair site after unilateral nerve stimulation
(20 Hz, 1 hour). With mice expressing axonal fluorescent proteins (thy1-YFP), we were
able to calculate the following at 5 and 7 days: percentage of regenerating axons
and arborizing axons, branches per axon, and regeneration distance and speed.
Results Brief stimulation significantly increases the percentage of regenerating axons (5
days: 35.5 vs. 27.3% nonstimulated, p < 0.05; 7 days: 43.3 vs. 33.9% nonstimulated, p < 0.05), mainly by increasing arborizing axons (5 days: 49.3 [4.4] vs. 33.9 [4.1]%
[p < 0.001]; 7 days: 42.2 [5.6] vs. 33.2 [3.1]% [p < 0.001]). Neither branches per arborizing axon nor regeneration speed were affected.
Conclusion Our morphological data analysis revealed that electrical stimulation in this model
increases axonal crossing of the repair site and promotes homogeneous perilesional
branching, but does not affect regeneration speed.
Keywords
electrical nerve stimulation - morphology - regeneration speed - branching - thy1-YFP
mice
