Glutamate and asparatate are two of the most prevalent neuroexcitatory substances in the CNS whereas GABA and taurine are two of the most prevalent neuroinhibitory substances. Although the precise neurophysiological functions of these amino acids have not been established, it is generally thought that they function as synaptic neurotransmitters. It is also known that these amino acids are metabolically compartmented, and this compartmentation may be related to their neurophysiological roles. The purpose of this proposed research is to provide a more complete explanation of the nature of this metabolic compartmentation, and to more fully establish the biochemical mechanisms which regulate the synthesis and degradation of the "neurotransmitter" pools of these amino acids. Another objective is to more clearly define the neurophysiological roles of these amino acids. We will conduct our experiments on several types of CNS preparations, including synaptosomes, isolated cerebellar granule, glial, and inhibitory neuronal cell preparations, as well as intact preparations such as the isolated toad brain and mouse brain in vivo. We will conduct studies on the uptake and metabolism of these amino acids and their possible metabolic precursors. We will also study the effects of potential metabolic regulators on the synthesis and degradation of these amino acids. The feasibility of the studies using purified cell populations obtained from the mouse cerebellum has been enhanced by our recent development of an innovative method for cell separation using magnetic microspheres. The results of our studies will lead to a more thorough understanding of the neurophysiological roles of these transmitter amino acids, and may provide insights into mechanisms which regulate certain neurological and mental disorders as well as being of value in the development of new therapeutic agents.