The effect of ethanol on the in vivo conversion of 5-HTP-14C to serotonin-14C, 5-hydroxyindoleacetaldehyde-14C and its metabolites in rat brain

Ethanol was administered i.p, to rats 1 hr prior to sacrifice and 5-HTP-¹⁴C was administered i.p. 30 min prior to sacrifice. Multiple doses of ethanol increased 5-HTP-¹⁴C found in the brain, possibly due to decreased efflux. Multiple doses of ethanol also increased the ratio of 5-hydroxyindoleacetaldehyde and/or 5-hydroxytryptophol to 5-HIAA. The possibility was considered that the increased neutral fraction and decreased acid fraction was due to inhibition of aldehyde dehydrogenase and activation of alcohol dehydrogenase by virtue of an ethanol-induced increase in brain NADPH/NADP ratio. High doses of ethanol, 6 lg/kg, slightly inhibited decar☐ylase and monoamine oxidase. The possibility was considered that inhibition of decar☐ylase and monoamine oxidase was due to acetaldehyde derived from ethanol