ARGININE AND ORNITHINE DECARBOXYLATION IN RODENT BRAIN - COINCIDENTALCHANGES DURING DEVELOPMENT AND AFTER ISCHEMIA

Agmatine, product of arginine decarboxylation, is known to occur mainl y in bacteria and plants where it serves as a precursor for the synthe sis of polyamines. Recently however, agmatine and arginine decarboxyla tion were detected in mammalian brain. Here we examined changes in rod ent brain arginine decarboxylation during cerebellum development and a fter global forebrain ischemia and compared them to changes in ornithi ne decarboxylase, the enzyme catalyzing the first limiting step in pol yamine synthesis. The findings suggest that (1) arginine decarboxylati on is transiently increased during development and after ischemia in p arallel to omithine decarboxylase activity. (2) Arginine decarboxylati on reaction is catalyzed by ornithine decarboxylase. (3) Decarboxylati on of both omithine and arginine becomes more pronounced in membrane f ractions, rather than in the cytosol, during brain maturation. (4) Dur ing development, omithine decarboxylase activity is reduced in the cyt osol, but increased in the membrane fractions.