| Objective: Previous clinical studies have shown that repetitive peripheral magnetic stimulation(rPMS)with a variety of treatment parameters has shown good therapeutic effects such as reducing pain,improving body function and improving neurological function.Complex Regional Pain Syndrome(CRPS)is a chronic painful disabling disease with chronic pain and multiple functional disorders,which seriously affects the physical and mental health of patients,increases the burden on families and social economy,and reduces the level of labor ability.The purpose of this study was to further clarify the therapeutic effect of 1Hz,3Hz and 10 Hz repetitive peripheral magnetic stimulation(rPMS)on pain in rats with complex regional pain syndrome(CRPSI)based on clinical work needs and previous clinical observations.The involvement of NK1-Receptor/Cav2.2 pain conduction pathway in pain relief provides a theoretical basis for the clinical treatment of pain with rPMS and expands the clinical indications of rPMS.Methods:This study used SD rats for the following three parts of the experiment: 1.SD rats were randomly divided into 5 groups and included in the statistics: a blank group of 6rats(without modeling or treatment),a control group of 5 rats(modeling but without rPMS treatment),a 1Hz rPMS treatment group of 12 rats(treated with 1Hz rPMS after successful modeling),and a 3Hz rPMS treatment group of 10 rats(treated with 3Hz rPMS after successful modeling)12 rats in the 10 Hz rPMS treatment group(treated with 10 Hz rPMS after successful modeling).The CRPS I rat model was established using the method of external fixation of tibia fractures for 4 weeks.After successful modeling,spontaneous pain,provocative pain,cold stimulation hyperalgesia,paw Withdraw Mechanical Threshold(PWMT),and thermal Withdraw Latency(PTWL)were measured,followed by rPMS treatment at 3 frequencies(1Hz,3Hz,10Hz).Treat continuously for 5 days per week,rest for 2 days,and the total treatment time is 2 weeks.At the same time,the blank group and control group grew naturally.After 2 weeks of treatment,the above pain was measured again,and the weight was measured,and the data was statistically analyzed.2.SD rats in the blank group,control group,and 10 Hz rPMS treatment group were subjected to tail vein blood collection before and after treatment,and the concentration of substance P was measured using ELISA detection method.3.After treatment,the blank group,control group,and 10 Hz rPMS treatment group were treated with rat tissue,including L5 dorsal root ganglia(DRG)and L5 level spinal cord,affected sciatic nerve,and affected foot skin.HE staining was performed on the skin,sciatic nerve,and L5 DRG,while immunohistochemistry was performed on the skin and L5 DRG to clarify the tissue distribution of substance P.The Real Time PCR method was used to determine the levels of substance P and Cav2.2 mRNA in DRG,as well as the expression of NK1 receptor and Cav2.2 mRNA in the lumbar spinal cord.The Western blot method was used to detect the levels of substance P and Cav2.2 protein in L5 DRG,lumbar spinal cord,and the expression of NK1 receptor protein in lumbar spinal cord.Results: 1.After modeling,all rats showed spontaneous pain,with the majority exhibiting first grade spontaneous pain,including curling up,digging holes,or hiding behavior.A small number of rats showed 2-4 grade spontaneous pain,including making painful sounds and leaning towards the affected side.There was no statistically significant difference between and within groups of spontaneous pain(P>0.05).2.Model rats also showed symptoms of irritable pain.After treatment,there was no obvious pattern of changes in the irritable pain rating of rats.The specific manifestations were that the irritable pain rating increased,decreased,and remained unchanged.There was no statistically significant difference between and within groups of spontaneous pain(P>0.05).3.After treatment with rPMS,compared to before treatment,the latency of cold stimulation hyperalgesia in the affected limbs of rats was prolonged(P<0.05).Compared with the control group,the latency of cold stimulation hyperalgesia in the affected limbs of rats in the 10 Hz rPMS treatment group was more significantly prolonged,and the difference was statistically significant(P<0.05).4.After treatment with rPMS,the PWMT of the affected limbs in rats increased(P<0.05);Compared with the control group,there was a statistically significant difference in the improvement rate of PWMT between the 3Hz rPMS and 10 Hz rPMS treatment groups(P<0.05).5.The CRPSI model group showed an increase in serum substance P,with a statistically significant difference compared to the control group(P<0.05);After treatment with 10 Hz rPMS,the serum concentration of substance P in CRPSI rats decreased compared to before treatment(P<0.05).The decrease rate of substance P concentration in the 10 Hz rPMS treatment group was higher than that in the control group,and the difference was statistically significant(P<0.05).6.After 2 weeks of treatment,edema was still observed in the L5 DRG and sciatic nerve of rats in the control group and 10 Hz rPMS treatment group,and inflammatory cells were still visible in the skin,which was more pronounced in the control group.7.Substance P was scattered in the L5 DRG and skin of the 10 Hz rPMS treatment group,less than the control group and more than the blank group.8.At 2 weeks of treatment,the expression of substance P mRNA in L5 DRG was statistically significant among the blank group,control group,and 10 Hz rPMS treatment group(P<0.05);The results of pairwise comparison showed that the mRNA levels of substance P in the control group were higher than those in the blank group and the 10 Hz rPMS treatment group(P<0.05);The mRNA level of substance P in the 10 Hz rPMS treatment group was higher than that in the blank group(P<0.05).9.The level of Cav2.2 mRNA in L5 DRG of the 10 Hz rPMS treatment group was significantly lower than that of the control group(P<0.05),and higher than that of the blank group(P<0.05).10.There was a statistically significant difference in the expression of NK1 receptor and Cav2.2 mRNA in the L5 level spinal cord among the three groups(P<0.05);Pairwise comparison showed that the 10 Hz rPMS treatment group was significantly lower than the control group(P<0.05),and higher than the blank group(P<0.05).11.The level of Cav2.2protein in L5 DRG of the 10 Hz rPMS treatment group was lower than that of the control group(P<0.05),but higher than that of the blank group(P<0.05).12.The level of Cav2.2protein in the L5 spinal cord of the 10 Hz rPMS treatment group was lower than that of the control group,but the difference was not statistically significant(P>0.05).The expression of Cav2.2 protein in the control group was higher than that in the blank group,and the difference was statistically significant(P<0.05).13.The level of NK1 receptor protein in the L5 spinal cord of the 10 Hz rPMS treatment group was significantly lower than that of the control group and higher than that of the blank group,with a statistically significant difference(P<0.05).Conclusion: 1.10 Hz rPMS can effectively treat cold stimulation induced pain in CRPSI rats.2.The treatment effect is frequency dependent,and the higher the frequency,the better the treatment effect.3.10 Hz rPMS treatment can effectively reduce the neuroinflammatory factor SP in the serum of CRPS Ⅰ rats.4.10 Hz rPMS can inhibit the expression of various components in the SP/NK1receptor/Cav2.2 pain pathway.5.10 Hz rPMS can effectively treat pain,and its mechanism is speculated to be related to the inhibition of the SP/NK1 receptor/Cav2.2 pain pathway. |
