Differentiation of disulfiram effects on central catecholamines and hepatic ethanol metabolism

Disulfiram is used in the treatment of chronic alcoholism, because of the unpleasant symptoms it provokes after ethanol intake. The underlying mechanism is believed to be the accumulation of acetaldehyde in the blood, due to inhibition of the liver aldehyde dehydrogenases. In addition, it is known that disulfiram also has some neurotoxic properties. The aim of our study was to investigate the relationship between the pharmacological and neurotoxicological properties of disulfiram with respect to the doses applied. Increasing doses of disulfiram (25, 50, 75, 100 and 150 mg/kg) were administered intraperitoneally to Wistar rats and the hepatic enzyme activities of alcohol and aldehyde dehydrogenases were measured. Also, in two brain subregions (midbrain and hypothalamus) the levels of noradrenaline, dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid were determined. The higher dose of disulfiram (150 mg/kg) produced lethal effects in all treated animals. Aldehyde dehydrogenase activities were inhibited by disulfiram in a dose-dependent way, while alcohol dehydrogenase was not affected at all. Concerning the levels of brain biogenic amines, disulfiram produced a significant reduction in noradrenaline and an increase in dopamine levels in both structures of the brain, in a dose-dependent way. However, the lowest dose applied (25 mg/kg) had no effects on brain catecholamines. It is known that high doses of disulfiram may cause severe encephalopathy and peripheral neuropathy in humans, which could be attributed to the impairment of the metabolism of brain biogenic amines, due to inhibition of dopamine-beta-hydroxylase. Our experimental data show that disulfiram affects the level of brain biogenic amines at dose levels higher than those inhibiting the activity of aldehyde dehydrogenase. Therefore, in clinical practice 'disulfiram reaction' could still be achieved with a low dosage regimen not producing neurotoxicity