[Effects of L-glutamic acid and its antagonist on spontaneous discharge of nucleus paragigantocellularis lateralis neurons in brainstem slice in rat].

We studied the effects of iontophoretic application of L-glutamic acid (L-Glu) and its antagonist DL-2-amino-5-phosphonovaleric acid (AP5) on the spontaneous discharge of the nucleus paragiganto-cellularis lateralis (PGCL) neurons and the influence of AP5 on L-Glu effect in brainstem slice in rat with the multibarrel microelectrode techniques. One hundred and thirty six units with stable spontaneous discharge were recorded in 51 rat brain slices, their discharge pattern being primarily a repetitive one. Both L-Glu and AP5 showed three kinds of effect on the PGCL neuronal spontaneous discharge: excitatory, inhibitory and no-effect, with the percentage of 80.65%, 8.06%, 11.29% for L-Glu and 28.00%, 8.00%, 64.00% for AP5 of the neurons tested, respectively. The excitatory effect showed a dose-response relationship. AP5 could block partially the excitatory effect of L-Glu on most neurons tested (71.87%). The results indicated that the neurons in PGCL in rat brain slice in vitro principally showed a spontaneous discharge with a repetitive firing pattern, and suggested that at cellular level there existed endogenous excitatory amino acid as neurotransmitter in PGCL and the neurons there possessed EAA receptors of both N-methyl-D-aspartate (NMDA) and non-NMDA subtypes.