Acute d-fenfluramine treatment greatly increased the level of phospho-Ser256-FoxO1 in the cerebral cortex, hippocampus, and striatum (Figure 1a). The effect of d-fenfluramine was statistically significant in all tested brain regions when data from the 2-hr d-fenfluramine treatment were compared to saline controls (Figure 1b). D-fenfluramine did not significantly change the level of total FoxO1, although a trend towards a decrease was observed in the hippocampus and striatum. Thus, the initial data suggest that a surge of synaptic serotonin can rapidly increase brain FoxO1 phosphorylation.
