| Objective:This study was designed to investigate the changes in mechanical and thermal pain threshold and the expression of Nav1.8 in DRG on SNI model rats after Electro-acupuncture,to further reveal the relationship between Nav1.8 and neuropathic pain and to elaborate the potential mechanism of electroacupuncture treatment on neuropathic pain.Methods:Fifty healthy Sprague-Dawley rats were randomly divided into 5 groups,10 in each group,and they were set as normal control group(Group N),model group(Group M),sham operation group(Group P),electroacupuncture group(Group E),and sham-electroacupuncture group(SE)group.The model selected was a spared nerve injury model.The specific method was to expose the sciatic nerve,and to branch off the phrenic nerve and the common peroneal nerve to retain the sural nerve.In the sham electroacupuncture group,only the sciatic nerve was exposed without breaking the branch.The electroacupuncture group received an electroacupuncture treatment on the day after medeling and every 2 days thereafter.The sham electroacupuncture group received a sham electroacupuncture at the same time.That is,only pierce into the steel needle without current.The mechanical and thermal pain thresholds of the five groups of rats were measured before modeling,on the 3rd,7th,and 14th days after modeling.The mechanical pain threshold is represented by the paw withdrawal threshold of 50%,and the thermal pain threshold is expressed by the rats’ foot-drive latency to thermal stimulation.After completion of the measurement on the 14th day after surgery,all rats’ DRGs were taken and the expression level of Nav1.8 in DRG was measured by Western Blot.Results:1.Regarding the mechanical pain threshold,there was a difference between the group M mechanical pain threshold on the third day(4.87±0.67g),seven days(3.11 ±0.91 g),and fourteen days(3.07±0.33g),p=0.019<0.05.The mechanical pain threshold in rats of group E and was different on the third day(6.04±1.03g),seven days(11.11±1.39g),and fourteen days(13.31±2.38g),p=0.023<0.05.Comparison between group E and group M:There was a difference in mechanical pain threshold between the 3rd,7th,and 14th days of electroacupuncture treatment(p=0.036<0.05).Between SE group and group M:after 3,7 and 14 days of electroacupuncture treatment,rats There was a significant difference between the mechanical pain threshold and the model group(p=0.0014<0.05).Between group E and group SE:After 3,7 and 14 days of treatment,there was a significant difference in the mechanical pain threshold of the rats(p=0.001<0.05).2.Regarding the thermal pain threshold:On the 7th day after modeling,the latency of right foot lift(13.3±1.80s)in group M was significantly lower than that before model establishment(28.87± 1.96s),and was significantly lower in group M and group N(26.8± 1.34s).Compared with the Group P(24.6±3.21s),there was a significant difference between the measurement of the latency of laden feet and P=0.004<0.05.On the 14th day after model establishment,the latent period(14.5±2.96s)in the group M was still lower than that in the Group N(24.7±1.53s)and Group P(22.4±3.01s),P=0.003<0.05.There was a difference between the three days(8.67± 1.27s),seven days(13.3 v 1.80s)and fourteen days(14.5±2.97s),p=0.018<0.05,There was no significant difference in group E between 3 days(16.17±1.70s),7 days(15.63±3.59s)and 14 days(21.43±1.89s)p=0.073>0.05.Comparison between group E and group M:there was a difference in foot-to-toe latency between the 3,7,and 14 days of electroacupuncture treatment(p=0.029<0.05).Comparison between group SE and group M:sham electroacupuncture treatment for 3,7,and 14 days There was no significant difference in the thermal pain threshold of rats(p=0.104>0,05).There was no significant difference in paw latency between the Group E and the SE group after 3,7 and 14 days of treatment(p=0.343>0.05).3.About Western Blot:There was a significant difference in gray value between group M and group N(p=0.028<0.05).There was a difference in gray value between group E and group M(p=0.025<0.05).Comparing group E with group SE,there was a significant difference in gray values,p=0.01<0.05.Conclusions:The rats with SNI showed a decrease in mechanical thermal pain thresholds,and the expression of Nav1.8 in dorsal root ganglion increased.Electroacupuncture treatment can significantly increase the mechanical and thermal pain thresholds in SNI model rats and reduce the expression of Nav1.8 in DRG,pseudo-electroacupuncture can improve mechanical allodynia in SNI rats,but it has no obvious effect on improving thermal hyperalgesia and reducing Nav1.8 expression. |
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