[Dopamine-stimulated glycosylation of rat hippocampal proteins in vitro: structure-response relationship]

Dopamine, but also other catecholamines (noradrenaline, adrenaline and isoprenaline), as well as L-dopa and alpha-methyl-dopa increase the incorporation of L-[1-3H]fucose into proteins of rat hippocampal slices. Among all substances that have been tested, dopamine exhibited the highest activity. Other non- or monohydroxylated phenylethylamine-derivatives (tyramine, octopamine, beta-phenylethylamine, metamphetamine) and pyrogallol had no effect on the fucosylation of hippocampal proteins. alpha-Methyl-dopa was less active than L-dopa. However, under the influence of alpha-methyl-dopa, an inhibitor of the dopadecarboxylase (aromatic L-amino acid decarboxylase, EC 4.1.1.28) the stimulatory effect of L-dopa on protein fucosylation was attenuated. From these results it is concluded that the dopamine-stimulated glycosylation of hippocampal proteins is triggered by (at least) two mechanisms, i.e. (1) via an activation of adenylate cyclase coupled dopamine receptor sites, and (2) via a mechanism which appears to be not related to an activation of transmitter-receptor sites but linked to the 3,4-dihydroxy-phenylethylamine-structure.