Mode of Action of Aliphatic Amino Acids on Cortical Synaptic Activity

Abstract

Several types of electrophysiological tests were applied to the analysis of the pharmacological actions of amino acids. Only the omega-amino acids had pronounced synaptic effects among the available C2 - C8 compounds. The [alpha]-amino acids, with the exception of glycine which has its amino group in the terminal position, are not synaptically active. Synaptic action is reduced or abolished by conversion to the [alpha], [omega]-diamino compound. The omega-amino acids all act to blockade synapses, but quantitative and qualitative differences characterize the compounds of different carbon length. The C2 - C5 compounds block predominantly the depolarizing, excitatory synapses, while the C6 and C8 omega-ammo acids block selectively the hyper-polarizing, inhibitory synapses. Within each group there are quantitative differences in effectiveness of selective action. The findings provide a new series of pharmacological tools for the analysis of the molecular structure and organization of central nervous synapses.