灸法镇痛中突触后抑制与生长抑素、P物质的关系

本实验采用特制的光热灸具在大鼠观察到灸次髎穴(穴位温度达45℃)可明显抑制背角神经元伤害性反应,新生大鼠辣椒素处理以毁损 C 类传入纤维可明显减弱此灸法的镇痛效应。光热灸环跳穴6分钟可明显延长腰髓背角投射神经元逆向动作电位的潜伏期,和针环跳的效应相似,说明针灸镇痛效应中均有突触后抑制参与。脊髓表面给以生长抑素抗血清明显阻断灸的突触后抑制效应,并减弱针的效应;而 P 物质抗血清只能阻断针效而不影响灸的效应。上述结果说明光热灸(45℃)和针刺相似,可通过突触后抑制实现镇痛效应。针刺的突触后抑制主要由 P 物质介导,生长抑素也参与,而灸的效应则主要由生长抑素介导。

The Role of Substance P and Somatestatin in Acupuncture and Moxibustion-Induced Postsynaptic Inhibition

Aim of investigation:Our previous work indicated that acupuncture and moxibustion(heatingacupoints with a special lamp)could produce inhibitory effects on the tail flick reflex and the nocicep-tire response of dorsal horn neurons.In the present study the role of somatostatin(SS)and substanceP(SP)in acupuncture and moxibustion-induced postsynaptic inhibition was further investigated.Methods:The experiments were performed on male adult Wistar rats.The antidromic action po-tential(AAP)induced by cervical cord stimulation was extracellularly recorded at lumbar cord(L_(3-4)).The latency of AAP was used to represent the excitability of postsynaptic projecting neurons.The effects of acupuncture(0.5 ms,3.3 Hz,2 mA)for five minutes or moxibustion(the tempera-ture up to 45-46℃)for six minutes at Huantiao points on the latency of AAP were observed.Andthen the effects of topical administration of SS or SP antiserum on either acupuncture or moxibustion-induced postsynaptie inhibition were observed.Results:The latency of AAP was markedly prolonged by acupuncture and moxibustion.Themaximal prolongation was 0.196±0.071 ms(n=12,P<0.02)and 0.176±0.062 ms(n=11,P<0.02)respectively.After topical administration of SS antiserum.(1:40,10μl),the latency of AAPwas slightly prolonged by either acupuncture or moxibustion.The maximal prolongation(0.041±0.029 ms and 0.016±0.020 ms)was significantly reduced by SS antiserum(P<0.05).While pre-treated with SP antiserum,the latency was still prolonged by moxibustion(0.142±0.067 ms),butnot by acupuncture(-0.003±0.046 ms).Conclusion:It is referred that postsynaptic inhibition may be involved in both acupuncture anal-gesia and moxibustion analgesia.The former is predominantly mediated by SP and partially by SS,while the latter mainly by SS but not by SP.