This investigation represents a biochemical approach aimed at explaining the occurrence and function of the new biogenic amines piperidine and pyrrolidine. The main objective is to clarify the source of piperidine, its metabolism and its localization in the brain of vertebrates. The distribution of piperidine and its subcellular localization will be studied in discrete parts of the brain; the uptake, biosynthesis and catabolism of piperidine will be studied both in vitro and in vivo by administering marked piperidine or marked precursors of this substance. The investigation includes a parallel biochemical study on pyrrolidine, the 4-carbon homologue of piperidine, which also occurs physiologically in the brain of vertebrates.