Methylenendioxyamphetamine produces serotonin nerve terminal loss and diminished behavioural and neurochemical responses to the antidepressant fluoxetine.
Andrew Harkin, Eamonn Shanahan, John P Kelly, Thomas J. Connor
The European journal of neuroscience August 2003 DOI: 10.1046/j.1460-9568.2003.02802.x (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Preclinical experimental study Peer reviewed |
|---|---|
| Population | Rats |
| Interventions | MDA Fluoxetine |
| Dose | MDA 7.5 mg/kg i.p. twice daily for 4 days; fluoxetine 5 or 20 mg/kg i.p. x 3 |
| Duration | 4 days MDA pretreatment, followed by 4-week washout, then fluoxetine administration and testing |
| Measures | modified rat forced-swimming test, 5-HIAA:5-HT ratio, [3H]paroxetine binding |
| Topics | Serotonin |
| Key findings | Prior MDA exposure attenuates fluoxetine-induced swimming behaviour and reduces fluoxetine's ability to lower serotonin metabolism in rat brain, suggesting diminished antidepressant responsiveness. |
Abstract
The effect of prior exposure to methylenedioxyamphetamine (MDA) on behavioural and neurochemical responses to fluoxetine were assessed in a rat model of antidepressant action. MDA (7.5 mg/kg, i.p.) was administered to rats twice daily for 4 consecutive days, and 4 weeks later the behavioural effect of fluoxetine (5 or 20 mg/kg; i.p. x 3) was examined in the modified rat forced-swimming test. In addition, the ability of fluoxetine to reduce serotonin (5-HT) metabolism was measured as an index of its efficacy in inhibiting 5-HT reuptake in vivo. In vehicle-treated rats, fluoxetine (5 and 20 mg/kg) produced a characteristic increase in swimming behaviour in the forced-swimming test. In contrast, fluoxetine-induced swimming was markedly attenuated in MDA-treated rats. MDA pretreatment resulted in 5-HT nerve terminal degeneration, indicated by reduced 5-HT and 5-HIAA concentrations in the frontal cortex, amygdala and hippocampus, and reduced [3H]paroxetine binding in the frontal cortex. In vehicle-treated rats, fluoxetine (5 and 20 mg/kg) decreased 5-HT metabolism (5-HIAA : 5-HT ratio) in the frontal cortex, amygdala and hippocampus. MDA pretreatment attenuated the ability of fluoxetine to reduce 5-HT metabolism in all brain regions examined. These findings are the first to demonstrate that prior exposure to the methylenedioxy-substituted amphetamine MDA results in diminished responsiveness to the antidepressant fluoxetine.