Abstract
We examined the response of neurons in the reticular formation near the nucleus ambiguus (NA) to the administration of substance P (SP). Whole-cell recording was applied to the neurons near the NA in coronal slice preparations of medulla oblongata isolated from infant rat. In the 8 of 18 neurons, bath application of SP (1μM) increased the frequency of spontaneous activities. In contrast, 4 neurons showed inhibited response by application of SP, and other 6 neurons showed no response. Several neurons were clamped at –60mV and recorded EPSCs evoked by electrical stimulation of adjacent area to the recording neuron. Bath application of SP induced spontaneous inward EPSCs independently generated to the electrical stimulation. This reaction to SP was abolished by application of non-NMDA type glutamate receptor antagonists, CNQX. Our previous studies have shown that administration of neurokinin-1 receptor (one of the a representative receptor of SP) antagonist near the NA inhibited gastric and respiratory movement in anesthetized rat. These results suggested that SP acts as neuromediator in the glutamatergic transmission near NA and participated in generating certain autonomic reactions. [Jpn J Physiol 55 Suppl:S192 (2005)]
