Role of serotonin transporter function in rat orbitofrontal cortex in impulsive choice

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Pharmacology

Background:

• Impulsivity is a key factor in drug abuse vulnerability.
• Serotonin (5-HT) system dysregulation in the prefrontal cortex is linked to impulsivity.
• Serotonin transporters (SERTs) regulate extracellular serotonin and may underlie individual differences in impulsivity.

Purpose of the Study:

• To investigate the role of SERT in mediating individual differences in impulsivity.
• To examine the relationship between SERT function in the orbitofrontal cortex (OFC) and medial prefrontal cortex (mPFC) and impulsive behaviors.
• To assess the effects of SERT inhibition on impulsive choice behavior.

Main Methods:

• Rats were assessed for impulsive action (cued go/no-go task) and impulsive choice (delay discounting task).
• Kinetic analysis of [(3)H]5-HT uptake by SERT in OFC and mPFC synaptosomes was performed.
• Fluoxetine, a selective SERT inhibitor, was microinjected into the OFC to evaluate its effects on impulsive choice.

Main Results:

• SERT Vmax in the OFC, but not mPFC, negatively correlated with delay discounting scores (impulsive choice).
• SERT Vmax did not correlate with performance on the cued go/no-go task (impulsive action).
• OFC microinjection of fluoxetine decreased impulsivity in high-impulsive rats but not in low-impulsive rats.

Conclusions:

• Enhanced SERT function in the OFC is associated with higher impulsive choice behavior.
• SERT in the OFC represents a potential molecular target for modulating impulsive choice.
• These findings contribute to understanding the neurobiological basis of impulsivity and drug abuse vulnerability.