Levels of dopamine (DA), noradrenaline (NA) and 5-hydroxytryptamine (serotonin, 5-HT) and their metabolites, and the activities of tyrosine hydroxylase (TH), tryptophan hydroxylase (TPH) and monoamine oxidase A and B (MAO-A and MAO-B) have been determined in the rat posterior thalamus after enucleation during postnatal development. DA and 5-HT turnover rate have been measured as 3,4-dihydroxyphenylalanine (DOPA) and 5-hydroxytryptophan (5-HTP) accumulation rates after central decarboxylase inhibition by 3-hydroxybenzylhydrazine (NSD-1015). The major changes were an increase in noradrenergic and serotoninergic metabolism in enucleated animals compared with control animals. A decrease of the MAO-A to MAO-B ratio during postnatal development was found.
5-Hydroxytryptophan Aging