Histamine H3-receptor activation inhibits dopamine synthesis in rat striatum
Por:
Molina-Hernández A., Nuñez A., Arias-Montaño J.-A.
Publicada:
1 ene 2000
Resumen:
Unilateral 6-hydroxydopamine lesion to rat substantia nigra pars compacta resulted in a modest, but significant, decrease in the specific binding of N-?-[methyl-3H]histamine (19 ± 5% reduction) to synaptosomal membranes from ipsilateral striata. Dopamine synthesis was assessed in striatal slices by determining [3H]DOPA accumulation after inhibition of DOPA decarboxylase. [3H]DOPA synthesis induced by 50mM K+ (151 ± 4% of basal) was prevented by either Ca2+ removal or by Ni2+. Depolarization- stimulated [3H]DOPA accumulation was reduced by the selective H3-agonist immepip (100 nM; 68 ± 7% inhibition). The effect of immepip was reversed by thioperamide (100 nM), a selective H3-antagonist. Taken together, our results indicate that histamine modulates striatal dopamine synthesis by acting at H3-receptors located on dopaminergic nerve terminals.