Excitatory amino acids as transmitter candidates of vibrissae afferent fibres to the rat trigeminal nucleus caudalis.

Responses of single neurones to vibrissal stimulation and to the iontophoretically applied putative neurotransmitters, L-glutamate and L-aspartate, were recorded in the trigeminal nucleus caudalis of the rat. Vibrissal responses were unaffected by the specific N-methyl-D-aspartate receptor antagonist, D-alpha-aminoadipate, but were antagonized by the broad-spectrum amino acid antagonist cis-2,3-piperidine dicarboxylate. These findings suggest that the neurotransmitter of vibrissae afferent fibres may be an endogenous excitatory amino acid acting at a receptor other than the N-methyl-D-aspartate receptor.