Changes in Histamine Metabolism in the Mouse Hypothalamus Induced by Acute Administration of Ethanol

Abstract: The effect of acute ethanol administration on histamine (HA) dynamics was examined in the mouse hypothalamus. The steady‐state level of HA did not change after intraperitoneal administration of ethanol (0.5–5 g/kg), whereas the level of tele‐methylhistamine (t‐MH), a predominant metabolite of brain HA, increased when 3 and 5 g/kg of ethanol was given. Pargyline hydrochloride (80 mg/kg, i.p.) increased the level of t‐MH by 72.2% 90 min after the treatment. Ethanol at any dose given did not significantly affect the t‐MH level in the pargyline‐pretreated mice. Decrease in the t‐MH level induced by metoprine (10 mg/kg, i.p.), an inhibitor of HA‐N‐methyltransferase, was suppressed by ethanol (5 g/kg), thereby suggesting inhibition of the elimination of brain t‐MH. Ethanol (5 g/kg) significantly delayed the depletion of HA induced by (S)‐α‐fluoromethylhistidine (50 mg/kg, i.v.), a specific inhibitor of histidine decarboxylase. Therefore, a large dose of ethanol apparently decreases HA turnover in the mouse hypothalamus.