| Objective To explore the mechanism of the dorsal root ganglia(DRG)P2X3 receptor involved in diabetic neuropathic pain(DNP)and intervention effect of low frequency electroacupuncture.Methods Experiment 1:Healthy male SD rats were randomly divided into control group and model group.After fasting for 16 hours,the model group was injected with STZ intraperitoneally,and the control group was injected with the same dose of citrate sodium citrate buffer.Fasting blood glucose(FBG),paw withdrawal latency(PWL)and paw withdrawal threshold(PWT)were observed before(base),7 days(7 days),14 days(14 days)and 21 days(21 days)respectively,and sciatic nerve and L4-L6 DRG were taken at each time point.The morphology of sciatic nerve and the expression of P2X3 receptor positive cells on L4-L6 DRG were observed by electron microscopy and immunofluorescence respectively.Experiment 2:healthy male SD rats were randomly divided into control+NS group,DNP+NS group and DNP+A-317491 group.At fourteenth days after STZ injection,100 nmol of P2X3 receptor inhibitor A-317491 solution was injected into the surface of left hind foot of rat in DNP+A-317491 group,and the other two groups were injected with the same amount of normal saline to observe the changes of FBG,PWL and PWT.Experiment 3:healthy male SD rats were randomly divided into control group,DNP group and DNP+EA group.After 14 days of STZ injection,DNP+EA group was intervened by Electroacupuncture at Zusanli and Kunlun points on both sides of rats.The frequency of electroacupuncture was 2Hz,and the intensity was 1mA intervened for 15min,and 2mA intervened for 15min,once a day,seven times.The morphology of FBG,PWL,PWT,sciatic nerve and the expression of DRG P2X3 receptor positive cells were observed.Experiment 4:healthy male SD rats were randomly divided into control+α β-me ATP,DNP+α β-me ATP and DNP+EA+α β-me ATP group.After the last intervention of electroacupuncture,rats in each group were injected with 100 nmol of P2X3 agonist α β-me ATP on the surface of left hind foot to observe the paw flinching.Results Experiment 1:The FBG of diabetic rats increased significantly on the 7th day after STZ injection and lasted until the 21st day after STZ injection;the PWL and PWT of diabetic rats decreased significantly on the 14th day after STZ injection.the electron microscope results of sciatic nerve showed that:from the 7th day to the 21st day after modeling,the arrangement of myelin sheath gradually disordered and expanded to the edge of axon and matrix,and there were obvious layered structure fragments on the 21st day after modeling.The results of immunofluorescence showed that compared with the control group,the positive cells of P2X3 on L4-L6 DRG increased significantly on the 7th,14th and 21st day after STZ injection,the difference was statistically significant.Experiment 2:A-317491 intervention had no effect on blood glucose of DNP rats;A-317491 injection could significantly improve PWL and PWT of DNP rats.Experiment 3:Electroacupuncture has no effect on FBG of DNP rats;Electroacupuncture can significantly improve PWL and PWT of DNP rats;Electroacupuncture has no significant change on the morphology of sciatic nerve of DNP rats;Electroacupuncture can inhibit the expression of L4-L6 DRG P2X3 receptor positive cells.Experiment 4:after injecting P2X3 receptor agonist α β-me ATP into the surface of the foot,the number of paw flinching of DNP rats was significantly higher than that of the control group(P<0.01);the number of paw flinching of DNP rats treated with electroacupuncture was decreased(P<0.01).Conclusion The upregulation of DRG P2X3 receptor expression is involved in diabetic neuralgia.Electroacupuncture has a good analgesic effect on DNP.The analgesic effect of Electroacupuncture on DNP is achieved by down regulating the upregulation of DRG P2X3 receptor expression. |
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