The stimulatory effect of magnetic fields on regeneration of the rat sciatic nerve is frequency dependent

The effects of exposure to sinusoidal magnetic fields on regeneration of the rat sciatic nerve were studied. Regeneration distances were measured after a crush lesion. The rats were exposed to a 0.1-mT magnetic field of various frequencies (50-2000 Hz) inside a pair of Helmholtz coils for various periods of time. Regeneration was measured by the pinch test or by immunocytochemical staining for neurofilaments 3, 4, or 6 days after the lesioning. Frequencies of 250, 500, and 1000 Hz significantly increased the regeneration distance. Higher (2000 Hz) and lower (50 Hz) frequencies had no effect. Maximal stimulation was obtained at 1000 Hz. At this frequency the rate of regeneration was increased by 24%. The results suggest that a broad frequency window exists within which the regeneration processes are sensitive to perturbation by magnetic fields and/or currents induced in the animal.