Journal of Neurophysiology, Vol 55, Issue 6 1283-1294, Copyright © 1986 by APS
Receptors for excitatory amino acids on neurons in rat pyriform cortex
J. M. ffrench-Mullen, N. Hori and D. O. Carpenter
The actions of a variety of agonists and antagonists of the excitatory
amino acids on rat pyriform cortex pyramidal neurons were studied in a
submerged, perfused brain slice. The order of potency for the agonists,
applied by ionophoresis, was kainate greater than quisqualate greater than
N-methyl-D-aspartate greater than aspartate = glutamate. The endogenous
monosynaptic excitation of pyramidal neurons upon stimulation of the
lateral olfactory tract was blocked post-synaptically by
DL-2-amino-4-phosphonobutyric acid, although this drug did not consistently
block any of the exogenous responses. The synaptic excitation was not
blocked, however, by antagonists presumed specific for the quisqualate
(glutamate diethyl ester), kainate, (gamma-D-glutamylglycine), or
N-methyl-D-aspartate (DL-2-amino-5-phosphonovaleric acid,
DL-2-amino-7-phosphonohetaonic acid) receptors. Several antagonists blocked
N-methyl-D-aspartate responses at lower concentrations than those to
aspartate, and other antagonists distinguished between kainate and
quisqualate responses. These results suggest that 1) pyriform neurons have
a variety of receptors that have properties somewhat different from those
found in other preparations and 2) the endogenous transmitter activates a
receptor distinct from those activated by kainate, quisqualate, and
N-methyl-D-aspartate.
