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.