Involvement of diamine oxidase in catabolism of 14C-putrescine in mice in vivo with special reference to the formation of gamma-aminobutyric acid.

Tissues of mice killed 2.5 or 30 min after injection of 14C-putrescine, contained 14C-gamma-aminobutyric acid, an unidentified 14C-compound, and unchanged 14C-putrescine. In mice pretreated with aminoguanidine, a powerful inhibitor of diamine oxidase, and then with 14C-putrescine, tissue levels of the radioactive catabolites, gamma-aminobutyric acid and the unidentified compound were markedly reduced. The data suggest that diamine oxidase is involved in the first step of putrescine metabolism and that intestine is the main site for this step. This and other aspects of putrescine metabolism are discussed.