The present study aimed to investigate whether NMDA and non-NMDA receptors in the caudate nucleus (Cd) were involved in SmI originating descending modulation on neurons in parafascicular nucleus (Pf) in acupuncture analgesia. It was found that after bilateral microinjection of D-AP5 and DNQX

the antagonist of NMDA and non-NMDA receptors respectively

into the head of Cd the inhibitory effect of conical excitation induced by glutamate application at SmI was obviously diminished

compared with that in the saline control group (ANOVA

P < 0. 05 ). In addition

the inhibitory effect of electro-acupuncture (EA) on nociceptive responses of neurons in Pf was also significantly attenuated by microinjection of DNQX

but not by that of D-APS. The attenuation was also significant statistically (ANOVA

P < 0. 05 ). It is indicated that both NMDA and non-NMDA receptors in Cd are involved in SmI originating descending modulation on nociceptive responses of neurons in Pf. Besides

non-NMDA receptors also participate in EA-induced inhibition on nociceptive responses of neurons in Pf.