Effect of electroshock on 5-HT metabolism in rat brain

Repeated electroshock treatment (EST) on three consecutive days was administered to 72 rats. The last treatment was given immediately after an injection of a tryptophan-hydroxylase inhibitor, H 22/54. The animals were killed three hours later, two to four brain stems were pooled, analysed for 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) and the values compared with a group of animals receiving H 22/54 only. A significant decrease in 5-HT was seen in the EST group indicating an increase in the release of 5-HT after the repeated treatment. When the level of 5-HIAA in the EST group was compared with the level in the group treated with H 22/54 alone, the difference was slight. The small increase could be explained by the rather slow turnover rate of 5-HT in the central nervous system (CNS) and thus of the synthesis of 5-HIAA. The possibility of an accelerated outflow of 5-HIAA from the CNS after EST should also be considered.