Effects of arginine-vasopressin on neuronal interaction from the area postrema to the nucleus tractus solitarii in rat brain slices

The effects of arginine-vasopressin (AVP) on area postrema (AP) neurons and the neuronal connection between the AP and nucleus tractus solitarii (NTS) were electrophysiologically investigated in rat medulla slices. In the AP, 27.9% of 129 neurons were excited by AVP and 20.5% were inhibited. The excitation was blocked by an V1 receptor antagonist. Synaptic transmission of the AP to the NTS was mainly mediated by non-N-methyl-D-aspartate (NMDA) receptors. Local application of AVP to the AP activated the NTS neurons. This excitation was also blocked by an NMDA antagonist. These results suggest that the excitation originating in the AP is conveyed to the NTS via non-NMDA receptors and then modified by NMDA receptor activation secondly. These processes may be important in the regulation of the arterial baroreceptor reflex. (C) 1998 Published by Elsevier Science Ireland Ltd. Ail rights reserved.