Study On The Therapeutic Effect And Mechanism Of Repetitive Peripheral Magnetic Stimulation In Neuropathic Pain Rats

Objective:To explore the therapeutic effect of different frequency of repeated peripheral magnetic stimulation(r PMS)on neuropathic pain(NP)rats and the effect on sympathetic sprouting and inflammatory factors in dorsal root ganglion(DRG).Methods:Sixty-four healthy adult male SD rats were selected and randomly divided into Sham group(Sham group),model group(SNL group),high frequency group(10Hz group)and low frequency group(1Hz group)by random number table method,with16 rats in each group.Ligation of the left lumbar 5 spinal nerve was performed,and NP model was made.In the sham operation group,only the left lumbar 5 spinal nerve was exposed without ligation.The magnetic stimulation instrument was set at 10 Hz and 1Hz respectively.After modeling,10 Hz group and 1Hz group were given corresponding r PMS treatment once a day.Paw withdrawal threshold(PWT)of each group was measured on the 1st,3rd,5th,7th,10 th and 14 th days after modeling,respectively.On the 7th day and 14 th day after modeling,the left lumbar 5 DRG was extracted in batches,and the sympathetic nerve fibers,interleukin-1β(IL-1β),interleukin-6(IL-6)and tumor necrosis factor α(TNFα)were stained by immunohistochemistry.The expressions of sympathetic sprouting and inflammatory cytokines IL-1β,IL-6 and TNF α were observed.Results:After modeling and before treatment,10 Hz group and 1Hz group 50%PWT in the 7th day was significantly higher than that before treatment and SNL group at the same time(P<0.01).50%PWT in the 10 Hz group decreased on the 10 th and 14 th day,and there was no significant difference in 50%PWT compared with the SNL group before treatment and at the same time(P>0.05),50%PWT of 1Hz group remained basically stable on the 10 th and 14 th day,and 50%PWT of 1Hz group was significantly higher than that of SNL group before treatment and at the same time(P<0.05).On the 7th and 14 th day after modeling,there was a large number of sympathetic sprouting in DRG of rats in SNL group,which was significantly higher than that in Sham group(P<0.05).Compared with SNL group,sympathetic sprouting in DRG in10 Hz and 1Hz groups was significantly reduced on the 7th and 14 th day(P<0.05).On the 7th and 14 th day after modeling,there was no significant difference in IL-1β expression in DRG among all groups(P>0.05),no significant difference in IL-6expression in 10 Hz group compared with SNL group(P>0.05),and the expression of IL-6 in 1Hz group was significantly reduced compared with SNL group(P<0.05).On the 7th day after modeling,TNFα in 10 Hz group was decreased compared with SNL group,but there was no significant statistical difference(P>0.05).TNFα in 1Hz group was significantly increased compared with SNL group,and its expression content was significantly higher than that in other groups(P<0.05).On the 14 th day,TNFα in10 Hz and 1Hz groups was significantly decreased compared with SNL group(P<0.05).Conclusion:rPMS can partially relieve pain symptoms in NP rats at different frequencies and times,inhibit sympathetic sprouting,and partially affect the changes of inflammatory factors,providing preliminary exploration direction for subsequent experimental studies.