| Diabetic peripheral neuropathy(DPN) is that diabetics have some symptoms of peripheral nerve dysfunction with the prolonged duration of diabetes excluding other causes. High blood sugar is the main cause of peripheral neuropathy. Currently, the cause of DPN has not been found. The main way to alleviate DPN clinically is to control the blood sugar and use neurotrophic drugs, but drugs have their limitations, and the price is also expensive. So many researchers have been exploring safer and more effective control methods. A large number of experimental studies confirm that the low-frequency, low-intensity pulsed electromagnetic fields(PEMF) can regulate diabetes microcirculation, glucose metabolism and lipid metabolism, and relieve nerve pain. Research on the mechanism of PEMF is not much, and requires a lot of experiments to explore. Based on this, we developed a low frequency, low intensity PEMF generator, through the establishment of diabetic rat model to study the effects of PEMF on DPN and to explore the mechanism of PEMF.In this study, the occurrence of EMF platform was based on the group’s earlier invention PEMF generating device(GHY-III, FMMU, Xi’an, China; China Patent no.ZL02224739.4) PEMF, We successfully constructed biological effect platform of electromagnetic fields to study diabetic effect of peripheral neuropathy in rats and microcirculation, and explore its mechanism.The main research contents and findings are as follows:Thirty adult male Sprague-Dawley rats(starting weight ~350 g) were used in this experiment. Eight rats randomly as control group(Ctrl group, N=8). Diabetes mellitus was induced by intraperitoneal injection of streptozotocin(45 mg kg-1) dissolved in 0.1 mol/L sodium citrate buffer. Blood glucose concentrations were higher than 20 mmol/L, and were taken as a standard diabetes model. Diabetic animals selected into the experiment were divided into 2 groups randomly, diabetic group(DM, N=8), and diabetes + pulsed electromagnetic fields group(DM+PEMF, N=8). After 2 days of successful modelling, electromagnetic interference with 15 Hz burst electromagnetic field(magnetic induction 1.6 mT) was applied from 9:00 A.M-5:00 P.M every day for 7 wk(49 days). Tests were done at Friday night of wk 0,1,3,5,7 after electromagnetic field had been applied on the diabetic rats. The experiments included:(1) Measuring mechanical withdrawal threshold(MWT) and thermal withdrawal threshold( TWT);(2) Measuring flow imaging using laser Doppler, and observing plantar perfusion changes of rat;(3) Observing the ultrastructure of rat sciatic by transmission electron microscopy, when the experiment was over;(4) Testing the sciatic nerve vascular endothelial growth factor(vascular endothelial growth factor, VEGF) expression;(5) Discussing the mechanism of PEMF for improving nerves and microcirculation.Experimental results showed that PEMF intervention did not change the weight and blood sugar; there was no significant difference between the two groups. MWT of DM and DM + PEMF was significantly lower than Control(P <0.01). MWT of DM + PEMF was significantly higher than DM(P <0.05). TWT of DM and DM + PEMF was significantly lower than Control(P <0.01). TWT of DM + PEMF was significantly higher than DM(P <0.05). Our current behavioral experiment results showed that diabetic rats had a sensitive pain and pathological features of peripheral nerve; PEMF could significantly reduce the diabetic rat sensitivity of thermal stimuli and mechanical stimuli. Blood vessels and hemorheology test showed that PEMF treatment, to a certain extent, could improve microcirculation, and PEMF mechanism on prevention and treatment of DPN may be closely related with the improvement of peripheral vascular microcirculation.Sciatic nerve ultrastructure observation showed that the axons of sciatic nerve of group DM degraded, nerve fibers demyelinated, and capillary endothelial cells swelled. Group DM+PEMF also had mild demyelination phenomenon of nerve fibers, and mild swelling phenomenon of capillary endothelial cells, comparing to those in DM group. Vascular endothelial growth factor immunohistochemistry results showed that diabetic rats sciatic nerve VEGF staining was positive, electromagnetic field irradiated rats VEGF immunohistochemical staining intensity was lower than the diabetic rats group, but they were both positive. The results suggest that PEMF may reduce VEGF expression by improving peripheral vascular microcirculation, preventing nerve furtherly damaged and improving ischemia hypoxia. We conclude that PEMF has a positive effect to the preventing and treating of DPN. |
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