| Objective:1. To observe the effect of low intensity pulsed ultrasound(LIPUS) on denervated skeletal muscle atrophy, and to explore the possibility of delaying the rate of skeletal muscle atrophy.2. To observe the effect of low intensity pulsed ultrasound in the treatment of injured nerve and its target muscle on nerve regeneration after peripheral nerve injury.Methods:Part one: 50 healthy male SD rats were randomly divided into five groups: sham operation group, model group, 60 mW/cm2, 110 mW/cm2, 170 mW/cm2 LIPUS treatment groups(groups A, B, C, D, E), n=10. The sciatic nerve of rats were exposed and transected by right femoral lateral incision for denervation animal model, the sciatic nerves in group A were exposed with the same method but not transected. 1 day after operation, the corresponding intensity LIPUS was applied to the right side gastrocnemius of groups C, D, E. At 4 weeks and 8 weeks after operation, the muscle wet weight ratio, muscle fiber diameter and cross-sectional area of the gastrocnemius were measured, the expression of Caspase-3, Caspase-8, caspase-9 was detected by Western Blot, the apoptosis was detected by TUNEL, the ultrastructure of gastrocnemius was observed with transmission electron microscope.Part two: 60 healthy male SD rats were randomly divided into four groups: model control group, ultrasound treat injured nerve group, ultrasound treat gastrocnemius muscle group, ultrasound combined treat injured nerve and gastrocnemius muscle group(group A’, B’, C ’, D’), n=15. The sciatic nerve of rats were exposed and cruched with the same hemostatic clamp by right femoral lateral incision for nerve injured animal model.1 day after operation, the 170 mW/cm2 LIPUS was applied to treat the corresponding parts of groups B’, C’, D ’, and group A’ without any treatment. At 1 and 2 weeks after operation, the expression of GAP-43, Ntn1 and Sema3 a protein were detected by Western Blot, at 2, 4, 6, 8 weeks after operation tested the SFI of each group, at 8 weeks after operation detected the NCV and the peak value of action potential, and the transmission electron microscope was used to observe the ultrastructure of nerve.Results:Part one: The wet weight ratio and fiber diameter and cross-sectional area were significantly lower in group B than those in groups C, D and E(P < 0.05). The expression of Caspase-3, Caspase-8 and Caspase-9 and the apoptosis index of groups C, D, E were significantly lower than those in group B(P<0.05). Transmission electron microscopy showed that myofilament dissolved, Z line broke, mitochondrial swelling and vacuolization in groups C, D, E were milder than those in group B.Part two: The expression of GAP-43 and Ntn1 protein in group B’, C’, D’ were increased than that in group A’(P<0.05).The expression of Sema3 a protein in group B’, C’, D’ were declined than that in group A’(P<0.05). Group D’ were superior to group B’ and group B’ were superior to group C’, there were statistically significant differences between group B’, C’ and group D’. The SFI at 2 weeks after operation had no significant difference between each groups. The SFI at 4, 6, 8 weeks after operation between group B’, D’ and group A’, group B’, C’ and group D’(P<0.05). At 8 weeks after operation, the peak value of action potential and nerve conduction velocity(NCV) in group B’, C’, D’ were better than those in group A’(P<0.05), and group D’ was superior to group B’and C’(P<0.05). Transmission electron microscopy showed that the myelinated nerve fibers in group B’, C’, D’ were densely distributed, myelin sheath thick and the organelles in axoplasmic such as mitochondria, microfilaments, microtubules are clear and complete than those in group A’, and there were no obvious connective tissue hyperplasia.Conclusion:LIPUS can retard the process of denervated skeletal muscle atrophy, and its mechanism may be related to regulate the expression of apoptosis related proteins and reduce the cell apoptosis. LIPUS can promote the nerve regeneration after peripheral nerve injured, its mechanism may be related to promote the expression of neurotrophic factor after sciatic nerve injured in rats. And LIPUS simultaneously treat the injured nerve and the target muscle of injured nerve has a synergistic effect on promoting nerve regeneration. |
PDF Full Text Request