Involvement of ionotropic glutamate receptors in low frequency electroacupuncture analgesia in rats

The present study was conducted to determine whether blockage of both N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid/kainate (AMPA/KA) receptors influences the induction of low frequency electroacupuncture (EA) analgesia. Although neither intrathecal injection of NMDA antagonist d-2-amino-5-phosphonopentanoic acid (d-AP-5) or AMPA/KA antagonist 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonami-de (NBQX) disodium alone had an effect on analgesia, spinal application of d-AP-5 and NBQX disodium significantly prevented analgesia induced by 2 Hz EA. The intrathecal injection of the excitatory amino acid NMDA produced analgesia for several minutes after intrathecal injection, as did EA stimulation. These results suggest that ionotropic glutamate receptors may be involved in the induction of 2 Hz EA analgesia.