AREA POSTREMA GLUTAMATE RECEPTORS MEDIATE RESPIRATORY AND GASTRIC RESPONSES IN THE RABBIT

THE role of NMDA and non-NMDA receptors of the area postrema (AP) in t he control of respiration and gastric motility was investigated in ana esthetized rabbits using microinjections (10-20 nl) of specific agonis ts or antagonists. NMDA (20 mM) or AMPA (10 mM) caused excitatory effe cts on respiration and gastric relaxation. Selective blockade of NMDA or non-NMDA receptors, respectively with D(-)-2-amino-5-phosphonopenta noic acid (D-AP5; 10 mM) and 6-nitro-7-sulphamoylbenzo(f)quinoxaline-2 ,3-dione (NBQX; 5 mM), decreased respiratory frequency and increased g astric tone. Both these effects were more marked following non-NMDA re ceptor blockade and were prevented by vagotomy. These findings show th at NMDA and non-NMDA receptors are present on AP neurones and have a r ole in the tonic control of respiration and gastric motility. (C) 1998 Rapid Science Ltd.