Thirty minutes of low intensity electrical stimulation promotes nerve regeneration after sciatic nerve crush injury in a rat model

We investigated whether electrical stimulation (ES) applied directly for 30 minutes after crushing injury to the sciatic nerves of rats could improve nerve regeneration. Two groups of animals were used in this study (n = 20 each): the ES group received 30 minutes of low intensity ES (20 Hz pulse rate, 2 uA amplitude) immediately after a standard crush injury, while the control group received no stimulation after injury. Both groups were followed up for three weeks. The sciatic function index (SFI) was calculated weekly. Mean conduction velocity (MCV) and peak voltage (PV) were calculated, and the sensory neurons in L4 and L5 dorsal root ganglia (DRG) were traced with Fluorogold in retrograde fashion and quantified at the end of the follow up period. Histomorphometric studies were also carried out in both groups. The ES group showed improved functional and sensory recovery compared to the control group three weeks after injury. SFI, MCV and the number of retrogradely labeled sensory neurons were significantly higher in the ES group. Additionally, axon counts, myelin thicknesses and G-ratio values were also higher in the ES group. Quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) showed an elevated expression of brain derived neurotrophic factor (BDNF) in DRG sensory neurons of the ES group five days post-injury. Here, we present the first evidence that the application of ES for 30 minutes immediately following crush injury is effective to promote nerve regeneration in a rat sciatic nerve model.