TIME-COURSE OF ETHANOL-INDUCED CHANGES IN SEROTONIN METABOLISM

The effect of acute ethanol consumption on serotonin metabolism was ex amined in healthy volunteers in the fasted and fed state by determinat ion of plasma and urinary levels of the serotonin metabolites 5-hydrox yindole-3-acetic acid (5-HIAA) and 5-hydroxytryptophol (5-HTOL). The p lasma and urinary levels of 5-HIAA were reduced by about 40% and 25%, while the 5-HTOL levels were increased on an average 7-fold and 50-fol d, respectively, after oral intake of ethanol (0.8 g/kg) over 30 min i n a fasted state. The maximal effect on both 5-HIAA and 5-HTOL levels was found 4-6 h after starting drinking. Urinary 5-HTOL and the 5-HTOL /5-HIAA ratio did not return to baseline until 19 h after the start of the administration (i.e., about 10 h after ethanol reached zero level ). The mean 24-h excretion of 5-HTOL was increased 15-fold by the etha nol intake, while the 5-HIAA excretion was not significantly different . A clear dose dependent effect was observed in one individual who als o ingested a lower amount of ethanol (0.5 g/kg). When ethanol (0.8 g/k g) was ingested over 3 h together with food, the urinary level of 5-HT OL and the 5-HTOL/5-HIAA ratio did not return to baseline until after 20-22 h. In other subjects who had unlimited access to ethanol and ing ested between 1.3-2.3 g/kg together with food, the time to reach basel ine 5-HTOL/5-HIAA ratio in urine ranged from 20 h to over 26 h.