The influence of continuous exposure to 50 Hz electric field on nerve regeneration in a rat peroneal nerve crush injury model

Abstract

The effect of power frequency electric field (EF) on nerve regeneration was investigated on a rat peroneal nerve crush injury model. The animals were assigned to three groups: 50 Hz EF and Static EF groups were exposed at 10 kV/m. The sham group was kept in the same setting without any EF applications. EF was uninterruptedly applied for 21 days postoperatively. Repeated measures analysis of daily walking tracks during EF exposure demonstrated lower toe spread recovery (TSR) in the 50 Hz EF group. Significant difference across the groups was found only at days 7, 8, 12, 16, 17, 20, and 21 when TSR was analyzed for each measurement time. Print length recovery and peroneal function index did not differ across the groups. Walking track parameters were found to recover to their baseline values by day 28 in all groups. Day 14 but not day 21 measurements revealed smaller nerve cross-sectional area, lower total regenerating axon area, and higher mean myelin debris area in 50 Hz EF group. Both day 14 and 21 measurements revealed higher total myelin debris area, lower EDL muscle weight, and lack of significant enlargement in nerve cross-section distal to the injury, compared to the normal counterpart in 50 Hz EF group. All differences were in keeping with lower rates of Wallerian degeneration and nerve regeneration in 50 Hz EF group. When walking track, histomorphometry and muscle weight are considered individually, their differences across the groups may appear to be subtle to derive a conclusion for a 50 Hz EF effect. However, their concordance with each other in direction of effect suggests that continuous 50 Hz EF exposure has a weak effect that is detrimental mostly to the rate of early nerve regeneration in this axonotmetic injury model. Recovery of walking tracks was not different between Static EF and Sham groups. This suggests that the surface charges that may indirectly affect walking behaviors of the rats, do not account for the lower recovery of TSR in 50 Hz EF group. Differences in nerve regeneration between 50 Hz EF and Static EF groups suggests that electric induction may be required for pure EF effects even though the estimated density of induced fields is not above the endogenous background level for the 50 Hz EF exposure in this study.

High‐ and low‐frequency transcutaneous electrical nerve stimulation delay sciatic nerve regeneration after crush lesion in the mouse

“…Thus, low ATP concentrations may have led to impairment of the normal regeneration process. Aydin et al (2006) submitted rats with a peroneal crush lesion to a whole‐body exposure of a 50‐Hz biphasic electrical field with an estimated induced electrical field of 10 mV/m and found a weak inhibition of regeneration expressed by morphological defects that did not interfere with gait function. It is difficult to estimate the strength of the electrical field when using the mouse model because the dielectric constant of mice is not yet known.…”

“…It is difficult to estimate the strength of the electrical field when using the mouse model because the dielectric constant of mice is not yet known. However, considering that a field magnitude of 10 mV/m would be the minimal induced field necessary to overcome the basic endogenous noise in cellular membranes and produce physical and biological effects ( Astumian et al, 1995; Aydin et al, 2006 ) , even very low electrical field intensities could cause negative biological effects on regeneration. Chen et al (2001) also found adverse detrimental consequences of electrical fields on peripheral nerve regeneration using percutaneous electrodes and a 1‐mA monophasic current.…”

The influence of pulsed electric field on hematological parameters in rat

“…Since the conductivity of water is very low at this operation frequency, water in all the living tissues and water bottles would be ineffective on the field lines produced in an exposed environment (Aydin et al, 2006; Okudan et al, 2006). As a precaution to avoid the slightest unwanted changes in the electrical properties, the cages were maintained clean.…”

The effect of the prenatal and post-natal long-term exposure to 50 Hz electric field on growth, pubertal development and IGF-1 levels in female Wistar rats

“…They were placed upright on wooden stands and positioned parallel to each other. In order not to disturb the field, leads were connected to the center of the plates on their outer sides (Aydin et al, 2006;Okudan et al, 2006).…”