Modification of rat brain 5-hydroxytryptamine metabolism by sublethal doses of organophosphate agents.

The early and late effects of sublethal doses of two organophosphate agents (paraoxon and soman) on 5-hydroxytryptamine (5-HT) metabolism were investigated in several rat brain areas. Parallel determinations of acetylcholinesterase (AcChE) inhibition were performed. An increase in 5-HT level was observed during the first phase of soman intoxication and a rise in 5-hydroxyindol acetic acid (5-HIAA) appeared in the early and late effects of both anticholinesterase agents with a predominant action in the striatum. These data suggested that paraoxon and soman induce a long-lasting increase in 5-HT turnover. This action cannot be related neither to the AcChE inhibition nor to the acetylcholine level.