Abstract Objective: Unlike central nervous system, peripheral nerves can repair after injury. Three steps are involved in nerve repair: axonal regeneration, target innervation and functional recovery. Axonal regeneration has two steps: growing nerve fibers find their targets in lesion that lead to its repair which is named the latency period and axon guidance along distal part. Following the appropriate target innervation, the regenerated axon can restore normal function by increasing size and myelination. In this paper, effect of direct application of brief current electrical stimulation (ES) on nerve regeneration in the sciatic nerve transection model in Wistar rats has been investigated. Materials and Methods: In this study, 15 adult male Wistar rats (250-350 g in weight) were used. All animals were anesthetized and the sciatic nerve was exposed at thigh level. In each animal, the proximal and distal stumps of the transected nerve were fixed with a single nylon suture by way of the epineurium and the outer walls of the silicone tube, leaving a 7-mm gap between the stumps and then the tube was filled with 9% chloride solution. All animals were randomly divided into three experimental groups: group I (N = 5), received ES for the duration of 10-minute immediately after the injury, group II (N = 5), received ES for the duration of 30-minute immediately after the injury, group III, the control group, was connected only by a conduit without receiving ES. The biphasic current stimulation was applied to the nerve of the animals in groups I and II at an amplitude of 1 μA, a pulse with of 100 μs, and a frequency of 20 Hz by placing the anode and the cathode stainless-silver electrode (0.5mm OD) connectors above the silicone tube and distally about 3mm bellow the silicone tube, respectively. Results: Functionality was evaluated through hot plate assessments biweekly during a 12-week period and by recording relative conduction velocity (NCV) at the end of the 12th week in all groups. Results of hot plate test indicate that after 10 weeks, the ES groups had a significant difference compared with control group (p<0.05). The groups receiving ES have shown effectiveness in promoting the speed of sciatic nerve regeneration after transection injury. Moreover, electrical stimulation for the duration of 30-minute has been more efficient than the duration of 10-minute in increasing NCV. Conclusion: Indeed, these results suggest that the electrical current stimulation with the proposed protocol appears to have a therapeutic effect on the functional recovery of a severed peripheral nerve injury. The electrical stimulation, especially 30-minute biphasic electrical stimulation accelerates the repair of the sensory fibers of the sciatic nerve after nerve transection injury. If the unstimulated lesioned nerve has enough time, it can also be sufficiently regenerated. On the other hand, the 30-minute ES accelerate Wallerian degeneration. Subsequently, it destroys, degrades and cleans-up those neurons that have lost their contacts with the neuron cell bodies (in the distal part). In addition, stimulation of the neuron cell bodies may lead to the production of materials which are necessary for growing the regenerating proximal nerve fibers.

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