Impulse magnetic stimulation facilitates synaptic regeneration in rats following sciatic nerve injury

Abstract

The current studies describing magnetic stimulation for treatment of nervous system diseases mainly focus on transcranial magnetic stimulation and rarely focus on spinal cord magnetic stimulation. Spinal cord magnetic stimulation has been confirmed to promote neural plasticity after injuries of spinal cord, brain and peripheral nerve. To evaluate the effects of impulse magnetic stimulation of the spinal cord on peripheral nerve regneration, we compressed a 3 mm segment located in the middle third of the hip using a sterilized artery forceps to induce ischemia. Then, all animals underwent impulse magnetic stimulation of the lumbar portion of spinal crod and spinal nerve roots daily for 1 month. Electron microscopy results showed that in and below the injuryed segment, the inflammation and demyelination of neural tissue were alleviated, apoptotic cells were reduced, and injured Schwann cells and myelin fibers were repaired. These findings suggest that high-frequency impulse magnetic stimulation of spinal cord and corresponding spinal nerve roots promotes synaptic regeneration following sciatic nerve injury.

Keywords: experimental neuropathy; impulse magnetic stimulation; neural regeneration; neuroplasticity; sciatic nerve lesion.

Figure 1

Ultramicroscopic observation of rat sciatic nerve stained according to the methods of Van Gizon and Mallory at 1 month after compression without treatment (electron transmission microscopy; × 5 000 in a, b; × 12 500 in c). (a) Demyelination of fibers and appearance of foamy myelin. ÌF: Myelin fiber; FM: “foamy” myelin; A: axon; NMF: non-myelin fiber. (b) Schwann cells with morphofunctional signs of macrophage. N: Nucleus; 1: myelin; 2: myelin fibers; L: lipids; Ls: lysosomes. (c) Apoptosis of SC. SC: Schwann cells; MF: myelin fibers; FM: “foamy” myelin; A: axon.

Figure 2

Ultramicroscopic observation of rat neuromuscular synapse stained according to the methods of Van Gizon and Mallory at 1 month after compression without treatment (electron transmission microscopy; × 16 000). Pathologically changed neuromuscular synapse with nerve destruction and folds of synaptic zone filled with collagen fiber (C). Single mitochondrion (MT) in postsynaptic (muscle) zone.

Figure 3

Ultramicroscopic observation of sciatic nerve stained according to the methods of Van Gizon and Mallory at 1 month after sciatic nerve injury and impulse magnetic stimulation treatment (electron transmission microscopy; × 16 000). SC: Schwann cell; ÌF: myelin fiber; A: axon.

Figure 4

Ultramicroscopic observation in muscle tissue stained according to the methods of Van Gizon and Mallory at 1 month after sciatic nerve injury and impulse magnetic stimulation treatment (electron transmission microscopy; × 16 000 in a and × 25 000 in b). (a) Recovery of cross-striation in myocytes. Hypertrophic Z-discs (arrows). (b) Neuromuscular synapse with completely recovered structure. 1: Postsynaptic zone; 2: presynaptic zone.