Metabolism of Polyamines in Mouse Neuroblastoma Cells in Culture:1 Formation of Gaba and Putreanine

Abstract —Polyamine metabolism of mouse neuroblastoma cells grown in culture was studied with special reference to the synthesis of GABA from putrescine and putreanine from spermidine. This study shows that neuroblastoma cells in the presence of a complete culture medium containing calf serum readily metabolized [14C]putrescine to GABA; the rate of synthesis is similar to the rate of synthesis of spermidine from putrescine. In the absence of serum the conversion of putrescine to GABA is minimal. In the presence of serum GABA formation is completely inhibited by the diamine oxidase inhibitor aminoguanidine. GABA synthesis does not occur in the absence of cells. The GABA synthesized is not readily metabolized to succinate or homocarnosine. Mouse neuroblastoma cells metabolized [14C]ornithine to putrescine, GABA, and spermidine. Spermidine was metabolized to putrescine, putreanine and spermine.