电针对大鼠类痛经痛反应、脊髓κ-受体表达及中脑导水管周围灰质脑啡肽和β-内啡肽含量的影响

目的:观察电针同神经节段支配的不同经穴与非穴对实验性类痛经模型大鼠中枢痛觉调制系统内阿片肽类物质的影响,探讨经穴效应的特异性。方法:动情间期雌性SD大鼠80只,随机分为盐水组、模型组、三阴交组、悬钟组、非穴组,每组16只。除盐水组外,其余各组大鼠注射苯甲酸雌二醇及缩宫素制备类痛经模型。电针治疗20min,观察大鼠的扭体反应,并应用免疫组化法和酶联免疫吸附法分别检测大鼠相应节段脊髓背角浅层κ-受体的表达和中脑导水管周围灰质(PAG)内脑啡肽(ENK)、β-内啡肽(β-EP)的含量。结果:与盐水组相比,模型组扭体潜伏期明显缩短(P<0.01),扭体次数和评分明显增加(P<0.01)。与模型组相比,各电针组扭体评分和次数均明显减少(P<0.01),三阴交组扭体潜伏期明显延长(P<0.05);三阴交组各节段脊髓背角浅层κ-受体表达均明显增加(P<0.01),悬钟和非穴组仅分别在S1节段(P<0.05)和L6节段(P<0.01)表达明显增加;三阴交和悬钟组PAG内ENK(P<0.01,P<0.05)和β-EP(P<0.01)含量明显升高。各电针组之间相比,三阴交组L1、L2、L6节段κ-受体表达与悬钟组相比明显升高(P<0.01),三阴交组各节段κ-受体表达与非穴组相比均明显升高(P<0.01,P<0.05);三阴交组的β-EP含量与悬钟组相比明显升高(P<0.01),三阴交组的ENK和β-EP含量与非穴组相比均明显升高(P<0.01),悬钟组的β-EP含量与非穴组相比明显升高(P<0.05)。结论:电针同神经节段支配的穴位与非穴位均可缓解大鼠的类痛经反应,并可通过调节中枢痛觉调制系统内的阿片肽类物质而达到镇痛作用。但穴位不同,其调节程度不同,说明经穴效应具有相对特异性,这种特异性不仅与神经节段有关,而且与其所属经络有关。

Effects of electroacupuncture on pain reactions, expression of spinal kappa-opioid receptor and contents of enkephalin and beta-endorphin in periaqueductal gray of midbrain in dysmenorrhea model rats

Objective To observe effects of electroacupuncture(EA) on the expression of κ-opioid receptor in the dorsal horn of the spinal cord and contents of enkephalin(ENK) and beta-endorphin(β-EP) in the periaqueductal gray(PAG) of midbrain in dysmenorrheal rats,so as to reveal its underlying mechanism in relieving dysmenorrhea.Methods A total of 80 female SD rats were randomized into saline control(control),model,Sanyinjiao(SP 6),Xuanzhong(GB 39),non-acupoint groups(16 rats/group).Dysmenorrhea model was established by subcutaneous injection of estradiol benzoate(0.5 mg/rat on the 1st day and 10th day,0.2 mg/rat from the 2nd day to the 9th day).One hour after the last injection,oxytocin(2 U/rat) was given intrape-ritoneally,for rats of the control group,the same dose of saline was given(i.p.).On the10th day,EA(2 Hz/100 Hz,0.1-0.3 mA) was applied to "Sanyinjiao"(SP 6),"Xuanzhong"(GB 39) and non-acupoint(the mid-point between the Stomach Meridian and Gallbladder Meridian,and in parallel with GB 39) for 20 min,respectively.Latency and number of writhing response,and writhing score(according to Schmauss’s and Yaksh’s method) were recorded.The expression of κ-opioid receptor(κ-OR) in T13,L1,L2,L6 and S1 segments of spinal cord was determined by immunohistochemistry,and the contents of ENK and β-EP in the midbrain PAG were assayed by ELISA.Results ①Compared with the saline control group,the writhing latency of the model group was significantly shortened(P<0.01),while the writhing times and writhing score of the model group were increased significantly(P<0.01).Compared with the model group,the writhing latency of SP 6 group was significantly prolonged(P<0.05),while the writhing scores and writhing times of the SP 6,GB 39 and the non-acupoint groups decreased significantly(P<0.01).② In comparison with the control group,κ-OR expression in the dorsal horn of L2 segment of spinal cord was upregulated significantly in the model group(P<0.05).Compared to the model group,κ-OR expression levels in the dorsal horns(DHs) of spinal T13,L1,L2,L6 and S1 segments in the SP 6 group were upregulated significantly(P<0.01).ENK and β-EP contents of PAG in the SP 6 and GB 39 groups were increased considerably(P<0.01,P<0.05).The effects of SP 6 were significantly superior to those of GB 39 in upregulating κ-OR expression of spinal L1,L2 and L6 DHs and in upregulating β-EP content of PAG;and superior to non-acupoint in upregulating κ-OR expression of spinal T13,L1,L2,L6 and S1 DHs and in increasing both ENK and β-EP contents of PAG(P<0.01,P<0.05).No significant differences were found between the non-acupoint group and the model group in writhing latency,κ-OR expression levels of spinal T13,L1,L2 and S1 DHs,and in ENK and β-EP contents of PAG(P>0.05).Conclusion EA of SP 6 can significantly alleviate pain reactions in dysmenorrhea rats,which is closely associated with its functions in upregulating spinal κ-OR expression and ENK and β-EP contents in PAG.EA of SP 6,GB 39 and non-acupoint has some different degrees of efficacies in relieving dysmenorrhea and in upregulating spinal κ-OR expression.