Excitatory transmission in the dorsal horn is in part mediated through APV-sensitive NMDA receptors.

The role of subtypes of excitatory amino acid receptor in synaptic transmission in the spinal dorsal horn has been studied in an in vitro slice preparation with well-preserved afferent inputs to the dorsal horn. Intracellular recordings were made from 30 dorsal horn neurons in laminae I-III of 18-28 day old rats. Superfusion of the slice with a Mg2+ zero solution resulted in an increase in the amplitude and duration of dorsal root-evoked excitatory postsynaptic potentials (EPSP) recorded intracellularly from dorsal horn neurons. Bath application of D-2-amino-5-phosphonovalerate (10(-5) M to 2.5 x 10(-5) M) or DL-2-amino-5-phosphonovalerate (10(-4) M to 2.5 x 10(-4) M) rapidly and reversibly abolished the later component of the EPSP evoked by activation of either group of primary afferents and selectively antagonized the N-methyl-D-aspartate-induced depolarization.