抄録
A pharmacological blockade of inhibition, simultaneous application of bicuculline and strychnine, induced a synchronized rhythmic activity (SRA) in the dorsal root. Application of APV or DNQX eliminated this SRA completely, which suggested the existence of glutamate receptors on the dorsal root. Here, the functional significance of glutamate receptors on the dorsal root was investigated in relation to presynaptic inhibition. In the isolated spinal cord preparation from newborn rats (6- 9 days old), the dorsal root (L4 or L5) was split into two or three rootlets. Using suction electrodes, one rootlet was stimulated electrically and primary afferent depolarization (PAD) was recorded from the adjacent rootlet. After simultaneous application of bicuculline and strychnine, PAD became smaller and much longer. This PAD was eliminated by DNQX or GYKI 53655 addition in the presence of APV. After application of bicuculline, strychnine, DNQX and deletion of extracellular Mg ions, the remaining NMDA component of PAD was not affected by addition of ifenprodil (up to 30 micro M), but was eliminated by a further addition of APV(25 micro M). It was concluded that AMPA type non-NMDA receptors and NMDA receptors without NR2B subunit on the dorsal root, contribute to PAD in rat spinal cord, and might play a significant role in presynaptic inhibition. [Jpn J Physiol 54 Suppl:S158 (2004)]
