To assess whether FoxOs can be regulated by serotonin in the mammalian brain, we first measured phosphorylation of brain FoxO1 and FoxO3a after serotonergic activity was increased by administration of d-fenfluramine, a drug that selectively stimulates serotonin release and blocks serotonin reuptake. C57BL/6 mice received an acute treatment with d-fenfluramine (50 mg/kg, i.p.) for 0.5, 1, and 2 hr. Following the d-fenfluramine injection, the Akt sensitive phosphorylation and the total levels of FoxO1 and FoxO3a in homogenates from cerebral cortex, hippocampus, and striatum were detected by immunoblots (Figure 1).
