Effects of high-potassium-induced depolarization on amino acid chemistry of the dorsal cochlear nucleus in rat brain slices

High KC was used to depolarize glia and neurons in order to study the effec ts on amino acid release from and concentrations within the dorsal cochlear nucleus (DCN) of brain slices. The release of glutamate, gamma-aminobutyra te (GABA) and glycine increased significantly during exposure to 50 mM K+, while glutamine and serine release decreased significantly during and/or af ter exposure, respectively. After 10 min of exposure to 50 mM K+, glutamine concentrations increased in all three layers of DCN slices, to more than 5 times the values in unexposed slices. In the presence of a glutamate uptak e blocker, L-trans-pyrrolidine-2,4-dicarboxylic acid (PDC), glutamine conce ntrations in all layers did not increase as much during 50 mM K+. Similar b ut smaller changes occurred for serine. Mean ATP concentrations were lower in 50 mM K+-exposed slices compared to control. The results suggest that de polarization, such as during increased neural activity, can greatly affect amino acid metabolism in the cochlear nucleus.