Liang Yi, Du Jun-Ying, Qiu Yu-Jie, Fang Jun-Fan, Liu Jin, Fang Jian-Qiao
Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
Department of Acupuncture and Moxibustion, The Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, 310005, China.
Chin J Integr Med. 2016 Sep;22(9):704-13. doi: 10.1007/s11655-015-2045-1. Epub 2015 Apr 6.
To investigate whether analgesic effect of electroacupuncture (EA) is affected by p38 mitogen-activated protein kinase (p38 MAPK) on microglia.
There were two experiments. The experiment 1: 40 male Sprague-Dawley (SD) rats were randomly divided into the normal, surgery, EA and sham EA groups, and the L5 spinal nerve ligation (SNL) on the right side was used to establish neuropathic pain model. EA was applied to bilateral Zusanli (ST36) and Kunlun (BL60) at 24, 48 and 72 h after SNL for 30 min, once per day. The paw withdrawal thresholds (PWTs) were measured before surgery (as base) and at 24, 25, 49 and 73 h after surgery. Phospho-p38 MAPK (p-p38 MAPK), oxycocin-42 (OX-42, marker of microglia), and glial fibrillary acidic protein (GFAP, marker of astrocyte) in bilateral spinal cord dorsal horn (SCDH) were detected by immunofluorescence, respectively. The experiment 2: 40 male SD rats were cannulated for SNL-induced neuropathic pain, and then were randomly divided into the dimethyl sulfoxide (DMSO), EA plus DMSO, 4-(4-fluorophenyl)-2-(4-methylsulfonylpheny)-5-(4-pyridyl)-1H-imidazole (SB203580) and EA plus SB203580 groups. SB203580 (30 nmol/L) was administered 5 min prior to EA treatment. The PWTs and OX-42 in bilateral SCDH were measured as mentioned above.
SNL-induced neuropathic pain reduced PWTs and increased the expression of p-p38 MAPK and OX-42 in bilateral lumbar SCDH of rats (P<0.01). Spinal p-p38 MAPK was only co-localized with OX-42 in our study. EA treatment significantly alleviated SNL-mediated mechanical hyperalgesia, and suppressed the expression of p-p38 MAPK and OX-42 in lumbar SCDH (P<0.05 or P<0.01). Intrathecal injection of low dose SB203580 had no influence on PWTs (P>0.05), but significantly inhibited the expression of OX-42 positive cells in bilateral SCDH (P<0.01 or P<0.05). EA plus SB203580 synergistically increased PWTs, and reduced the expression of bilateral spinal OX-42 (P<0.01 or P<0.05).
The central mechanism of EA-induced anti-hyperalgesia may be partially associated with the reduced expression of p-p38 MAPK, and subsequently reducing the activation of OX-42 in neuropathic pain. Therefore, EA may be a new complementary and alternative therapy for neuropathic pain.
探讨电针（EA）的镇痛作用是否受小胶质细胞中p38丝裂原活化蛋白激酶（p38 MAPK）的影响。
进行了两项实验。实验1：将40只雄性Sprague-Dawley（SD）大鼠随机分为正常组、手术组、电针组和假电针组，采用右侧L5脊神经结扎（SNL）建立神经病理性疼痛模型。在SNL后24、48和72小时对双侧足三里（ST36）和昆仑（BL60）进行电针治疗30分钟，每天1次。在手术前（作为基线）以及手术后24、25、49和73小时测量 paw withdrawal thresholds（PWTs）。分别通过免疫荧光检测双侧脊髓背角（SCDH）中的磷酸化p38 MAPK（p-p38 MAPK）、oxycocin-42（OX-42，小胶质细胞标志物）和胶质纤维酸性蛋白（GFAP，星形胶质细胞标志物）。实验2：将40只雄性SD大鼠进行SNL诱导的神经病理性疼痛插管，然后随机分为二甲亚砜（DMSO）组、电针加DMSO组、4-（4-氟苯基）-2-（4-甲基磺酰苯基）-5-（4-吡啶基）-1H-咪唑（SB203580）组和电针加SB203580组。在电针治疗前5分钟给予SB203580（30 nmol/L）。如上所述测量双侧SCDH中的PWTs和OX-42。
SNL诱导的神经病理性疼痛降低了大鼠双侧腰段SCDH的PWTs，并增加了p-p38 MAPK和OX-42的表达（P<0.01）。在本研究中，脊髓p-p38 MAPK仅与OX-42共定位。电针治疗显著减轻了SNL介导的机械性痛觉过敏，并抑制了腰段SCDH中p-p38 MAPK和OX-42的表达（P<0.05或P<0.01）。鞘内注射低剂量SB203580对PWTs无影响（P>0.05），但显著抑制了双侧SCDH中OX-42阳性细胞的表达（P<0.01或P<0.
