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Objective To investigate the role of ERK signaling pathway in spinal cord in reduction of neuropathic pain (NP) by electro-acupuncture (EA) at Zusanli and Yanglingquan.Methods Fifty male SpragueDawley rats,weighing 180-220 g,in which the intrathecal catheter was successfully placed without complications,were randomly divided into 5 groups (n =10 each):sham operation group (S group),chronic constrictive injury (CCI) group,acupuncture at acupoint group (EA group),acupuncture at non-acupoint group (NA-EA group),and ERK inhibitor U0126 group (U0126 group).NP was induced by CCI in groups CCI,EA,NA-EA and U0126.The animals were anesthetized with intraperitoneal chloral hydrate 300 mg/kg.The right sciatic nerve was exposed and 4 ligatures were placed on the sciatic nerve at 1 mm intervals.EA (intensity ＜ 1.5 mA,frequency 2Hz) of Zusanli and Yanglingquan lasting 30 min was performed once a day for 6 days starting from 4th day after induction of NP in group EA.EA was performed at the points 5 mm lateral to the acupoints of Zusanli and Yanglingquan on the operated side in group NA-EA.Intrathecal U0126 5 μg was started on 4th day after induction of NP twice a day for 6 consecutive days.The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured at 1 day before CCI (T0,baseline) and at days 3,5,7 and 9 after CCI (T1-4).The rats were sacrificed on 10th day after induction of NP and the right lumbar segment (L4-6) of the spinal cord was removed for determination of the expression of P2X3 receptor protein and mRNA,ERK1/2 and phosphorylated ERK1/2 (p-ERK1/2) in the spinal cord dorsal horn.Results Compared with group S,MWT was significantly decreased,TWL was significantly shortened,the expression of P2X3 receptor protein and mRNA,and p-ERK1/2 was up-regulated in the other 4 groups (P ＜ 0.01).Compared with CCI group,MWT was significantly increased,TWL was significantly prolenged,the expression of P2X3 receptor protein and mRNA,and p-ERK1/2 was downregulated in EA and U0126 groups (P ＜ 0.01),and no significant change in the parameters mentioned above was found in NA-EA group (P ＞ 0.05).Compared with EA group,MWT was significantly increased,TWL was significantly prolonged,the expression of P2X3 receptor protein and mRNA,and p-ERK1/2 was down-regulated in U0126 group (P ＜ 0.01).Conclusion ERK signaling pathway in spinal cord is involved in reduction of NP by EA at Zusanli and Yanglingquan.
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0.05),but the cure rate in the treatment group was higher than that in the control group(P
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[Objective] To observe analgesic action produced by electvoacupuncture (EA) of different intensity in adjuvant arthritis (AA) rats. [Methods] AA rat models were induced and the rats were randomized into 3 groups: group A, group B and group C. Group A and group B were treated with EA on points of Kunlun (BL60) and Yangtingquan (GB34) at the same wave type and wave frequency but at different electric current (3.5mA and 5.5mA respectively). Group C was performed with mimic EA. Pain threshold (PT) in the three groups before and after EA was observed. [Results] After EA, PT of the affected limb in group A and group B was increased (P0.05). [Conclusion] Analgesic action of EA at the same wave type and wave frequency while at different electric current is different: analgesic action at middle-intensity current is superior to that at large-intensity current; its possible mechanism is related to the participation of central nervous system.