Visualisation of AMPA binding sites in the brain stem of normotensive and hypertensive rats

The present study has employed in vitro receptor autoradiography with (S)-[ H-3]-5-fluorowillardiine (10 nM) to visualise the presence of alpha-amino-3 -hydroxy-5-methylisoxazole-4-propionic acid(AMPA) binding sites in the brai n stems of adult(16-18 weeks) normotensive (Wistar-Kyoto (WKY) and Don Ryu (DRY)) and Spontaneously Hypertensive (SHR) rats. Similar topographic distr ibution and density of (S)-[H-3]-5-fluorowillardiine binding was observed i n the nucleus tractus solitarius (NTS) of all three strains. Specific (S)-[ H-3]-5-fluorowillardiine binding sites were also visualised in sections of nodose ganglion from adult WKY rats, demonstrating that va,aal afferent per ikarya possess AMPA binding sites. However, while unilateral vagal deaffere ntation did not result in a significant decrease in binding site density in the caudal half of the rat NTS, the visualisation of AMPA binding sites on the nodose ganglion is consistent with the existence of a population of bi nding sites on vagal afferent terminals. In the caudal half of the rat NTS, AMPA binding sites appear to be predominantly postsynaptic in nature. (C) 1999 Elsevier Science B.V. All rights reserved.