Regional distribution of 3-O-methyl-DOPA in the cortex and subcortical structures in the rat: effect of aging

Dihydroxyphenylalanine (DOPA) and its metabolite 3-O-methyl-DOPA (3-OMDOPA) have been identified as normal constituents in blood, CSF and brain in human and several animal species. In the present study, we report results of 3-OMDOPA measurements in seven cortical areas, hippocampus and striatum of young (3-month-old), middle aged (10-month-old) and aged (27-month-old) rats. 3-OMDOPA was identified in all the areas considered. Regional differences were observed, with the highest levels being found in the hippocampus and the somatomotor and pyriform cortex. A marked increase in the level of 3-OMDOPA was observed in all the cortical areas and in the hippocampus of aged rats. In contrast, this level remained unchanged in the striatum. These modifications were compared to those observed in the levels of dopamine (DA) in the same areas.