The excitation of mammalian central neurones by amino acids.

Publisher Website
Google Scholar
Abstract
The relative potencies of a number of analogues of L-glutamate as excitants of thalamic neurons in the rat were compared. The most powerful compounds were kainate, ibotenate and (.+-.)cis-1-amino-1,3-dicarboxycyclopentane [ADCP]. The D- and L-isomers of glutamate and aspartate were compared. Whereas D-glutamate is approximately 1/2 as active as the L-form, D-aspartate is more potent than L-aspartate. Computer analysis indicated that ibotenate and ADCP have relatively fixed and similar C.alpha.-N, C.omega.-N and C.alpha.-C.omega. interatomic distances which can also be achieved by glutamate in certain conformations of the molecule, but not by aspartate. Parallel examination of the antagonists glutamate diethylester and D-.alpha.-aminoadipate showed that the former preferentially reduces L-glutamate effects while the latter blocks the actions of other amino acid excitants more readily than those of L-glutamate. The evidence is consistent with the hypothesis that at least 2 populations of neuronal receptors for the excitatory amino acids exist.