Effect of ethanol on the hydroxylation of tyrosine and tryptophan in rat brain in vivo

Abstract

Abstract Various doses of ethanol were injected intraperitoneally into rats. After 20 min, 3-hydroxybenzylhydrazine (NSD 1015), an inhibitor of aromatic amino-acid decarboxylase was injected and 30 min later the animals were killed. The amount of dopa accumulating in brain as a consequence of decarboxylase inhibition was significantly increased by moderate doses of ethanol (up to 4 g kg−1). There was no corresponding effect on 5-hydroxytryptophan. The effect on dopa was found both in a dopamine- and a noradrenaline-dominated area of the brain, suggesting that catecholamine synthesis is stimulated by ethanol in both types of neuron. The data lend support to the hypothesis of Carlsson, Engel & Svensson (1972) that cerebral catecholamines are involved in the central stimulation induced by ethanol.